Black start control method and device based on multiple converter sub-arrays

Abstract

The application provides a black start control method and device based on multiple converter subarrays, wherein after the control switch is controlled to be in a closed state and the converters in each converter subarray are controlled to be in a start state, the working processes of a first voltage adjustment stage to an Nth voltage adjustment stage are sequentially performed; and in the nth voltage adjustment stage in the first voltage adjustment stage to the Nth voltage adjustment stage, the nth target voltage adjustment instruction is synchronously sent to each converter subarray to control each converter in the converter subarray to establish an nth target alternating current voltage, so that the nth target alternating current voltage is converted into an nth target bus alternating current voltage input to the first alternating current bus through the first transformer. The process of establishing the rated voltage of the first alternating current bus is divided into multiple stages, the subarray circulating current problem is solved, and the reliability of the power grid black start is improved.

Description

Technical Field

[0001] This application applies to the field of power electronics technology, and in particular relates to a black-start control method and device based on multiple converter subarrays. Background Technology

[0002] With the development of power grid interconnection and long-distance power transmission technologies, the scale of power systems is expanding daily, and power grids at all levels are continuously interconnected. The reliability and stability of system operation are also constantly improving. However, due to increasingly complex operating environments and the unavoidable nature of various natural disasters, the network structure and dynamic characteristics of power systems are becoming more complex, with more stringent and unpredictable operating conditions. The risk of large-scale power outages still exists. Power system black start refers to the process of restoring the entire system to operation and supplying power to users in the shortest possible time, minimizing power outage losses, when large-scale power outages are caused by human error, natural disasters, or equipment failures, and there is no external power source. This involves starting units with self-starting capabilities within the system, which in turn starts units without self-starting capabilities, gradually expanding the system's recovery scope.

[0003] In new power systems, grid voltage can be established through power electronic converters in energy storage systems or photovoltaic power generation systems, enabling black starts and restoring grid power supply. This type of black start method does not require additional grid infrastructure; it only requires existing converters and control systems. Typically, the massive inrush current generated during the closing of the first transformer or transmission line in a power system may directly trigger the converter's protection mechanism, causing black start failure. Therefore, the method of closing the circuit before starting the power supply is generally used to prevent this inrush. However, because medium- and high-voltage transmission lines typically have large capacitive reactive loads during steady-state operation, often far exceeding the rated capacity of a single converter subarray, multiple converter subarrays need to be started and operated simultaneously to support the grid in establishing a stable voltage. When multiple converter subarrays in the power grid differ in their distribution location, phased construction, etc., resulting in inconsistencies in port impedance and communication delay with the upper-level controller, problems such as circulating current in the converter subarrays can easily occur when controlling the output voltage of multiple converter subarrays simultaneously. This can lead to failure of local overcurrent protection and black start, reducing the reliability of black start based on the coordinated operation of multiple converter subarrays. Summary of the Invention

[0004] This application provides a black start control method and apparatus based on multiple converter subarrays to improve the reliability of black start based on the coordinated operation of multiple converter subarrays.

[0005] In a first aspect, embodiments of this application provide a black-start controller based on multiple converter subarrays, wherein at least one converter subarray includes at least one converter, the input port of each converter subarray is connected to a DC source, and the output port of each converter subarray is connected to a first AC bus via a first transformer and a control switch. The black-start controller is used to sequentially execute the operation process from the first voltage adjustment stage to the Nth voltage adjustment stage after controlling the control switch to be closed and controlling each converter in the converter subarray to be in the power-on state; and, within the nth voltage adjustment stage from the first to the Nth voltage adjustment stages, synchronously sending the nth target voltage adjustment command to each converter subarray, controlling each converter in the converter subarray to establish the nth target AC voltage, so that the nth target AC voltage is converted into the nth target bus AC voltage input to the first AC bus via the first transformer. Where n and N are integers greater than 1; 1≤n≤N, the nth target AC voltage is greater than the (n-1)th target AC voltage, the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

[0006] For example, in this application, the second target AC voltage is greater than the first target AC voltage, the third target AC voltage is greater than the second target AC voltage, ..., the Nth target AC voltage is greater than the (N-1)th target AC voltage. Also, the second target bus AC voltage is greater than the first target bus AC voltage, the third target bus AC voltage is greater than the second target bus AC voltage, ..., the Nth target bus AC voltage is greater than the (N-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

[0007] In this embodiment, the process of establishing the rated voltage of the first AC bus is divided into multiple stages. In each stage, the voltage is increased by a certain amount, and this process is repeated until the rated voltage is established, thereby helping the power grid establish voltage and restore the operation of the power system. This can solve the problem of circulating current in the subarray during the black start process of multiple converter subarrays in a power plant or microgrid system, improve the reliability of the power grid black start, and enhance the applicability of multi-converter subarray coordinated black start scenarios, especially the black start scenario of transmission lines with large reactive power.

[0008] For example, in the first voltage adjustment phase, the controller synchronously sends the first target voltage adjustment command to the converter subarray. Each converter in the subarray can establish the first target AC voltage based on the first target voltage adjustment command. This first target AC voltage is then converted by the corresponding first transformer and output to the first AC bus as the first target bus AC voltage. In the second voltage adjustment phase, the controller synchronously sends the second target voltage adjustment command to the converter subarray. Each converter in the subarray can establish the second target AC voltage based on the second target voltage adjustment command. This second target AC voltage is then converted by the corresponding first transformer and output to the first AC bus as the second target bus AC voltage. The rest are similar and can be deduced sequentially, so they will not be elaborated here.

[0009] In some possible implementations, the black-start controller includes: a first controller and a plurality of second controllers; wherein the first controller and the plurality of second controllers are communicatively connected, each converter in each converter subarray has a drive controller, the plurality of second controllers are configured one-to-one with the plurality of converter subarrays, and the second controllers are communicatively connected to the drive controllers of the converters in the correspondingly configured converter subarrays. Furthermore, the first controller is used to synchronously send an nth target voltage adjustment command to each of the plurality of second controllers based on the nth target AC voltage data in a pre-established adjustment sequence during the nth voltage adjustment stage. Any one of the plurality of second controllers is used to send an nth voltage output command to the communicatively connected drive controller based on the received nth target voltage adjustment command. The drive controller is used to control the corresponding converter to establish the nth target AC voltage based on the received nth voltage output command. The adjustment sequence includes target AC voltage data from the first target AC voltage to the Nth target AC voltage data arranged sequentially.

[0010] For example, the second controller may be located in the same area as the corresponding converter subarray. For instance, the second controller may be located within the operating area of ​​the corresponding converter subarray.

[0011] For example, the power system also includes an uninterrupted power supply (UPS), with each UPS connected to a second controller. The UPS stores electrical energy transmitted from the power grid before power is interrupted, and supplies the stored energy to the second controller when power is interrupted, thus achieving a black start. In practical use, the power system also includes a power module connected between the UPS and the second controller, through which the UPS can supply power to the second controller.

[0012] For example, the first controller may have a communication component for communicating with external devices or external servers. The communication component may include a network communication protocol module such as a WIFI module or a wired Ethernet communication protocol module, so that the first controller can communicate with external devices or external servers to exchange control signals and data signals.

[0013] For example, the second controller may have a communication component for communicating with external devices or external servers. This communication component may include a network communication protocol module such as a WIFI module or a wired Ethernet communication protocol module, so that the second controller can communicate with external devices or external servers to exchange control signals and data signals.

[0014] Optionally, the communication component of the first controller is connected to the communication component of the second controller to enable communication of control signals and data signals between the first controller and the second controller.

[0015] In some examples, when black-start control is required, the operator inputs a black-start initiation command to the first controller. Upon receiving this command, the first controller selects the converter subarrays participating in the black-start process and confirms that the selected subarrays are powered on or available. Then, it sends an initial black-start preparation command to the second controller. Based on this command, the second controller sends a target black-start preparation command to the drive controllers of the converters within the subarrays. If the drive controllers of the converters in the subarrays are ready, they send an initial black-start preparation completion command to the second controller. The second controller then sends a target black-start preparation completion command to the first controller. Upon receiving the target black-start preparation completion command, the first controller can begin sequentially executing the operation of the first to Nth voltage regulation stages.

[0016] In other examples, the operator can input a black-start initiation command to the first controller via the higher-level controller. Upon receiving this command, the first controller selects the converter subarrays participating in the black-start process and determines that the selected subarrays are powered on or available. Then, it sends an initial black-start preparation command to the second controller. Based on this command, the second controller sends a target black-start preparation command to the drive controllers of the converters within the subarray. If the drive controllers of the converters in the subarray are ready, they send an initial black-start preparation completion command to the second controller. The second controller then sends a target black-start preparation completion command to the first controller. Upon receiving the target black-start preparation completion command, the first controller can begin sequentially executing the voltage adjustment stages from the first to the Nth. For example, the second controller can also be used to monitor the operating status information within the corresponding converter subarray, such as the voltage, current, frequency, and power (active power and reactive power) of the converters within the subarray. The first controller can obtain information such as voltage, current, frequency, and power (active power and reactive power) of the converter subarray from the second controller.

[0017] The first controller stores a pre-established adjustment sequence. This adjustment sequence contains sequentially arranged target AC voltage data from the first target AC voltage data to the Nth target AC voltage data.

[0018] This application does not limit the storage method of the first target AC voltage data to the Nth target AC voltage data. For example, the first target AC voltage data to the Nth target AC voltage data can be stored in the first controller in binary, decimal or hexadecimal format.

[0019] For example, during the first voltage adjustment phase, the first controller synchronously sends a first target voltage adjustment command to the second controller based on the first target AC voltage data in a pre-established adjustment sequence. The second controller can then synchronously receive the first target voltage adjustment command. The second controller, based on the received first target voltage adjustment command, sends a first voltage output command to the drive controller in the converter subarray, which is communicatively connected to it. The drive controller in the converter subarray, based on the received first voltage output command, controls the converters in the subarray to convert DC power into the first target AC voltage of the power frequency AC current, establishing the first target AC voltage V1. The rest are similar and can be deduced sequentially, without further elaboration.

[0020] In some possible implementations, the adjustment sequence further includes one or more power equalization control data. Furthermore, in the adjustment sequence, the nth target AC voltage data corresponds to and is adjacent to the qth power equalization control data, and the nth target AC voltage data is set before the qth power equalization control data. For example, if the adjustment sequence includes multiple power equalization control data, and the number of power equalization control data included in the adjustment sequence is Q, then the adjustment sequence includes the 1st to the Qth power equalization control data. Q is an integer greater than 1, q is a positive integer, and 1 ≤ q ≤ Q.

[0021] For example, the first controller is further configured to determine the q-th target power of each converter subarray based on the q-th power equalization control data in the adjustment sequence, and synchronously send a q-th power adjustment command carrying the corresponding q-th target power to the second controller corresponding to each converter subarray based on the q-th target power of each converter subarray. The second controller is further configured to send a q-th power output command to the drive controller connected in communication based on the received q-th power adjustment command. The drive controller is further configured to control the corresponding converter to output the q-th target power based on the received q-th power output command.

[0022] For example, the first controller is also used to determine the first target power of the converter subarray based on the first power balancing control data in the adjustment sequence, and synchronously send a first power adjustment command carrying the first target power to the second controller based on the first target power of the converter subarray. Furthermore, the second controller is also used to send a first power output command to the drive controller in the converter subarray that is communicatively connected to it, based on the received first power adjustment command carrying the first target power. The drive controller in the converter subarray is also used to control the corresponding converter to output the first target power based on the received first power output command, thereby controlling the power balancing between the converter subarrays and solving problems such as load power imbalance. The rest are similar and can be deduced sequentially, and will not be elaborated further here.

[0023] In some examples, the number of power equalization control data points in the adjustment sequence is the same as the number of target AC voltage data points. Furthermore, the target AC voltage data points and power equalization control data points alternate in the adjustment sequence. That is, for Q = N, the adjustment sequence has: the first target AC voltage data point, the first power equalization control data point, the second target AC voltage data point, the second power equalization control data point, the third target AC voltage data point, the third power equalization control data point, ..., the Nth target AC voltage data point, and the Qth power equalization control data point.

[0024] In some other examples, in the adjustment sequence, the number of power balance control data is less than the number of target AC voltage data. Moreover, in the adjustment sequence, at least one target AC voltage data is set between two adjacent power balance control data. That is to say, Q < N, and this adjustment sequence can have: no power balance control data is set between some of the target AC voltage data.

[0025] In some possible implementation manners, the first controller is further configured to obtain the power of the output port of each converter sub-array, determine the average power of each converter sub-array according to the power of the output port of each converter sub-array and the number of converters in each converter sub-array, and determine the determined average power of each converter sub-array as the q-th target power of each converter sub-array.

[0026] Exemplarily, the first controller can obtain the power of the output port of each converter sub-array from the monitoring system. Alternatively, the first controller can also obtain the power of the output port of the corresponding converter sub-array from the first controller corresponding to each converter sub-array.

[0027] In some possible implementation manners, the drive controller is further configured to, after controlling the corresponding converter to establish the n-th target AC voltage, control the corresponding converter to correct the phase of the established n-th target AC voltage based on the AC voltage of the output port of the converter sub-array where the converter is located.

[0028] Exemplarily, the drive controller of each converter in each converter sub-array is further configured to, after controlling the corresponding converter to establish the n-th target AC voltage, control the corresponding converter to correct the phase of the established n-th target AC voltage based on the AC voltage of the output port of the converter sub-array where the converter is located. For example, the drive controller is further configured to, after controlling the corresponding converter to establish the first target AC voltage, control the corresponding converter to correct the phase of the established first target AC voltage based on the AC voltage of the output port of the converter sub-array where the converter is located. The same applies to the rest, and so on by analogy, which will not be elaborated here.

[0029] In some possible implementations, the power system further includes a switch control module, and a first controller is communicatively connected to the switch control module; wherein the switch control module is connected to a control switch. The first controller is also configured to send an identifier (e.g., ID) of each of the plurality of converter subarrays to the switch control module, and the switch control module is configured to control the closing of the control switch connected to each of the plurality of converter subarrays. The first controller is also configured to synchronously send a subarray start command to a second controller corresponding to each of the plurality of converter subarrays. The second controller is also configured to send a converter start command to a communicatively connected drive controller based on the received subarray start command. The drive controller is configured to control the corresponding converter to start based on the received converter start command.

[0030] For example, firstly, the switch control module controls the control switch connected to each converter subarray to close, so that the output port of each converter in each converter subarray is connected to the input terminal of the first transformer in parallel. Furthermore, the output terminal of each first transformer is connected to the first AC bus in parallel. This enables the converters of each converter subarray and the AC power grid requiring startup to be interconnected in the circuit. Then, the first controller synchronously sends a subarray start command to the second controller corresponding to each of the multiple converter subarrays. Next, each second controller, based on the received subarray start command, sends a converter power-on command to the communication-connected drive controller. Then, the drive controller, based on the received converter power-on command, controls the corresponding converter to power on, so that each converter in the converter subarray is in a powered-on or usable state before a black start is implemented.

[0031] In some possible implementations, the power system further includes a switch control module, and a first controller is communicatively connected to the switch control module; wherein the switch control module is connected to a control switch. The first controller is also configured to send an identifier (e.g., ID) of each of the plurality of converter subarrays to the switch control module, and the switch control module is configured to control the closing of control switches connected to a first portion of the plurality of converter subarrays, and to control the closing of control switches connected to a second portion of the plurality of converter subarrays; the number of converter subarrays in the first portion of the converter subarrays is less than the number of converter subarrays in the second portion of the converter subarrays. The first controller is further configured to, after the control switch connecting the first part of the converter subarray is closed, synchronously send a first subarray start command to the second controller corresponding to each converter subarray in the first part of the converter subarray, and synchronously send an initial voltage adjustment command to the second controller corresponding to each converter subarray in the first part of the converter subarray; and, after the control switch connecting the second part of the converter subarray is closed, synchronously send a second subarray start command to the second controller corresponding to each converter subarray in the second part of the converter subarray. The second controller corresponding to the first part of the converter subarray is further configured to, based on the received first subarray start command, send a converter power-on command to the communication-connected drive controller, and, based on the received initial voltage adjustment command, send an initial voltage output command to the communication-connected drive controller. The second controller corresponding to the second part of the converter subarray is further configured to, based on the received second subarray start command, send a converter power-on command to the communication-connected drive controller. The drive controller in each converter subarray is configured to control the corresponding converter to power on based on the received converter power-on command. The drive controller, which is communicatively connected to the second controller corresponding to the first part of the converter subarray, is also used to control the corresponding converter to establish an initial AC voltage based on the received initial voltage output command, so that the initial AC voltage is converted into an initial bus AC voltage input to the first AC bus by the first transformer; wherein the initial bus AC voltage is less than the first target bus AC voltage.

[0032] For example, firstly, the switch control module can control the closing of the control switch connecting the first part of the converter subarrays in the multiple converter subarrays, so that the output port of each converter in each converter subarray in the first part of the converter subarray is connected to the input terminal of the corresponding transformer in parallel, and the output terminal of the transformer corresponding to the first part of the converter subarray is connected to the first AC bus. Then, the first controller synchronously sends a first part of the subarray start command to the second controller corresponding to each converter subarray in the first part of the converter subarray. Then, based on the received first part of the subarray start command, the second controller corresponding to the first part of the converter subarray sends a converter power-on command to the drive controller connected in communication. Then, based on the received converter power-on command, the drive controller controls the corresponding converter to power on so that each converter in the first part of the converter subarray is in a powered-on or usable state before a black start is performed. Then, the first controller synchronously sends an initial voltage adjustment command to the second controller corresponding to each converter subarray in the first part of the converter subarray. Subsequently, the second controller corresponding to each converter subarray in the first part of the converter subarray sends an initial voltage output command to the drive controller connected in communication, based on the received initial voltage adjustment command. Then, the drive controller, based on the received initial voltage output command, controls the corresponding converter to establish an initial AC voltage, so that the initial AC voltage is converted into an initial bus AC voltage input to the first AC bus via the first transformer. Next, the switch control module controls the control switch connecting the second part of the converter subarrays in the plurality of converter subarrays to close. Then, the first controller synchronously sends a second subarray start command to the second controller corresponding to each converter subarray in the second part of the converter subarray. Then, the second controller corresponding to the second subarray, based on the received second subarray start command, sends a converter power-on command to the drive controller connected in communication. The drive controller, based on the received converter power-on command, controls the corresponding converter to power on, so that each converter in the second part of the converter subarray is in a powered-on or usable state before implementing a black start.

[0033] For example, the number of converter subarrays in the first part of the converter subarray is less than the number of converter subarrays in the second part of the converter subarray. For example, the first part of the converter subarray includes one of a plurality of converter subarrays, and the second part of the converter subarray includes the remaining converter subarrays in the plurality of converter subarrays other than the first part of the converter subarray.

[0034] For example, the UPS is also connected to a switch control module to provide stored electrical energy to the switch control module when the power grid or electrical equipment is interrupted, thereby enabling black start.

[0035] In some possible implementations, each converter in each converter subarray is a voltage-source converter. The second controller is further configured to synchronously send the nth voltage output command to the drive controller in each converter in the corresponding converter subarray.

[0036] For example, the second controller synchronously sends the first voltage output command to the drive controller in each converter of the corresponding converter subarray, so that the drive controller in each converter of the converter subarray controls the switching frequency of the switch in the corresponding converter based on the received first voltage output command, thereby converting the electrical energy of the DC source into the first target AC voltage of the power frequency AC, and establishing the first target AC voltage. Furthermore, the process of the second controller controlling the establishment of the remaining target AC voltages can be deduced sequentially, and will not be elaborated here.

[0037] In some possible implementations, each converter in each converter subarray is a voltage-source converter; and one converter in each converter subarray is a master converter, while the remaining converters are slave converters. The second controller is further configured to send the nth voltage output command to the drive controller in the corresponding master converter of the converter subarray. The drive controller connected to the master converter is further configured to control the master converter to establish the nth target AC voltage based on the received nth voltage output command, and to send a slave voltage output command to the drive controller in the slave converter based on the received nth voltage output command. The drive controller in the slave converter is configured to control the slave converter to establish the nth target AC voltage based on the received slave voltage output command.

[0038] For example, one converter in the converter subarray is the master converter, and the remaining converters are slave converters. The second controller corresponding to this converter subarray is used to send the nth voltage output command to the drive controller in the master converter of the converter subarray. The drive controller connected to the master converter in the converter subarray is further used to control the master converter to establish the nth target AC voltage based on the received nth voltage output command, and to send a slave voltage output command to the drive controller in the slave converter of the converter subarray based on the received nth voltage output command. The drive controller in the slave converter of the converter subarray is used to control the slave converter to establish the nth target AC voltage based on the received slave voltage output command.

[0039] In some possible implementations, one converter in each converter subarray is a voltage-source converter, and the rest are current-source converters. The second controller is further configured to send the nth voltage output command to the drive controller connected to the voltage-source converter.

[0040] For example, one converter in a converter subarray is a voltage-source converter, and the remaining converters are current-source converters. The second controller corresponding to this converter subarray is further configured to send the nth voltage output command to the drive controller connected to the voltage-source converter in the converter subarray. The voltage at the output port of the current-source converter in the converter subarray can follow the voltage at the output port of the voltage-source converter.

[0041] The power system described in this application is applicable to scenarios such as photovoltaic power generation systems, energy storage power stations, and microgrids.

[0042] This application does not limit the specific structure of the converter subarray. For example, in this application, the converter subarray may include converters, monitors, etc. The converter may have a drive controller, which controls the switching frequency of the switches in the converter, enabling the converter to convert electrical energy from the DC source into AC power at power frequency (e.g., 50Hz).

[0043] This application does not limit the specific implementation of the DC source. For example, the DC source can be configured as an energy storage device, in which case the converter is an energy storage converter, the converter subarray is an energy storage converter subarray, and the energy storage converter can convert the electrical energy in the energy storage device into power frequency (e.g., 50Hz) AC power. Alternatively, the DC source can also be configured as a photovoltaic power generation device, in which case the converter is a photovoltaic converter, the converter subarray is a photovoltaic converter subarray, and the photovoltaic converter can convert the electrical energy in the photovoltaic power generation device into power frequency (e.g., 50Hz) AC power.

[0044] It should be noted that power frequency generally refers to the frequency of mains electricity. In my country, the power frequency is 50Hz, while other countries may use 60Hz. If the frequency of the power frequency AC is 50Hz, its power frequency period is 0.02 seconds.

[0045] In some possible implementations, in the first to the Nth voltage adjustment stages, there is an interval between the start times of each two adjacent voltage adjustment stages, and this interval is greater than one power frequency cycle. For example, there is an interval between the start time of the second voltage adjustment stage and the start time of the first voltage adjustment stage, and this interval is greater than one power frequency cycle. There is an interval between the start time of the third voltage adjustment stage and the start time of the second voltage adjustment stage, and this interval is greater than one power frequency cycle. ... There is an interval between the start time of the Nth voltage adjustment stage and the start time of the (N-1)th voltage adjustment stage, and this interval is greater than one power frequency cycle.

[0046] For example, the time interval between the start times of any two adjacent voltage adjustment stages is the same. For instance, there is a time interval between the start time of the second voltage adjustment stage and the start time of the first voltage adjustment stage, a time interval between the start time of the third voltage adjustment stage and the start time of the second voltage adjustment stage, and so on, with the start time of the Nth voltage adjustment stage being the same as the start time of the (N-1)th voltage adjustment stage.

[0047] Optionally, the interval time is K times the power frequency cycle. For example, if K=2, then the above interval time is twice the power frequency cycle. Or, if K=3, then the above interval time is three times the power frequency cycle. Or, if K=4, then the above interval time is four times the power frequency cycle. It should be noted that the specific value of K can be determined according to the actual application requirements, and is not limited here.

[0048] In some possible implementations, in the first to the Nth voltage adjustment stages, at least a portion of the voltage difference between the target AC voltages of any two adjacent voltage adjustment stages is the same. For example, in the first to the Nth voltage adjustment stages, at least a portion of the absolute values ​​of the voltage difference between the target AC voltages of any two adjacent voltage adjustment stages are the same.

[0049] For example, at least a portion of the absolute values ​​of the voltage difference between the target AC voltages in each adjacent two voltage adjustment stages can be the same. For instance, the absolute value of the voltage difference between the first and second target AC voltages is the same as the absolute value of the voltage difference between the second and third target AC voltages. The absolute value of the voltage difference between the second and third target AC voltages is the same as the absolute value of the voltage difference between the third and fourth target AC voltages. The absolute value of the voltage difference between the third and fourth target AC voltages is different from the absolute value of the voltage difference between the fourth and fifth target AC voltages. The absolute value of the voltage difference between the fourth and fifth target AC voltages is the same as the absolute value of the voltage difference between the fifth and sixth target AC voltages. The rest can be deduced similarly, and will not be elaborated further here.

[0050] For example, the voltage difference between the target AC voltages of any two adjacent voltage adjustment stages can also be made the same. For instance, the absolute values ​​of the voltage differences between the first and second target AC voltages, the second and third target AC voltages, the third and fourth target AC voltages, the fourth and fifth target AC voltages, and the fifth and sixth target AC voltages can all be the same. The rest can be deduced similarly and will not be elaborated upon here.

[0051] In some possible implementations, in the first to the Nth voltage adjustment stages, the voltage difference between the target AC voltages of each adjacent pair of voltage adjustment stages increases sequentially. For example, in the first to the Nth voltage adjustment stages, the absolute value of the voltage difference between the target AC voltages of each adjacent pair of voltage adjustment stages increases sequentially. Exemplarily, the absolute value of the voltage difference between the first and second target AC voltages is less than the absolute value of the voltage difference between the second and third target AC voltages, the absolute value of the voltage difference between the second and third target AC voltages is less than the absolute value of the voltage difference between the third and fourth target AC voltages, the absolute value of the voltage difference between the third and fourth target AC voltages is less than the absolute value of the voltage difference between the fourth and fifth target AC voltages, and the absolute value of the voltage difference between the fifth and sixth target AC voltages is less than the absolute value of the voltage difference between the sixth and seventh target AC voltages. The rest can be deduced in the same way, and will not be elaborated here.

[0052] In some possible implementations, in the first to the Nth voltage adjustment stages, the voltage difference between the target AC voltages of each adjacent two voltage adjustment stages decreases sequentially. For example, in the first to the Nth voltage adjustment stages, the absolute value of the voltage difference between the target AC voltages of each adjacent two voltage adjustment stages decreases sequentially. Exemplarily, the absolute value of the voltage difference between the first and second target AC voltages is greater than the absolute value of the voltage difference between the second and third target AC voltages, the absolute value of the voltage difference between the second and third target AC voltages is greater than the absolute value of the voltage difference between the third and fourth target AC voltages, the absolute value of the voltage difference between the third and fourth target AC voltages is greater than the absolute value of the voltage difference between the fourth and fifth target AC voltages, and the absolute value of the voltage difference between the fifth and sixth target AC voltages is greater than the absolute value of the voltage difference between the sixth and seventh target AC voltages. The rest can be deduced in the same way, and will not be elaborated here.

[0053] Secondly, embodiments of this application also provide a main controller based on multiple converter subarrays. At least one of the multiple converter subarrays includes at least one converter. The input port of each of the multiple converter subarrays is connected to a DC source, and the output port of each of the multiple converter subarrays is connected to a first AC bus through a first transformer and a control switch. The main controller is communicatively connected to multiple second controllers, which are configured one-to-one with the multiple converter subarrays, and the second controllers are used to control the operation of the corresponding converter subarrays. The main controller, after controlling the control switch to be closed and ensuring the converters in each converter subarray are in the power-on state, sequentially executes the operation process from the first voltage adjustment stage to the Nth voltage adjustment stage. Furthermore, within the nth voltage adjustment stage, it synchronously sends the nth target voltage adjustment command to each second controller, enabling each second controller to control its corresponding converter subarray to establish the nth target AC voltage. The nth target AC voltage is then converted by the first transformer into the nth target bus AC voltage input to the first AC bus. Where n and N are integers greater than 1; 1 ≤ n ≤ N; the nth target AC voltage is greater than the (n-1)th target AC voltage; the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage; and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

[0054] For example, in this application, the second target AC voltage is greater than the first target AC voltage, the third target AC voltage is greater than the second target AC voltage, ..., the Nth target AC voltage is greater than the (N-1)th target AC voltage. Also, the second target bus AC voltage is greater than the first target bus AC voltage, the third target bus AC voltage is greater than the second target bus AC voltage, ..., the Nth target bus AC voltage is greater than the (N-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

[0055] In this embodiment, the main controller divides the process of establishing the rated voltage of the first AC bus into multiple stages. In each stage, the voltage is increased by a certain amount, and this process is repeated until the rated voltage is established, thereby helping the power grid establish voltage and restore the operation of the power system. This can solve the problem of circulating current in the subarray during the black start process of multiple converter subarrays in a power plant or microgrid system, improve the reliability of the power grid black start, and enhance the applicability of multi-converter subarray coordinated black start scenarios, especially the black start scenario of transmission lines with large reactive power.

[0056] In some possible implementations, each converter in the converter subarray has a drive controller, and a second controller is communicatively connected to the drive controller of the corresponding converter in the converter subarray. Furthermore, the main controller, during the nth voltage adjustment phase, synchronously sends an nth target voltage adjustment command to each second controller based on the nth target AC voltage data in a pre-established adjustment sequence. This causes the second controller to send an nth voltage output command to the communicatively connected drive controller based on the received nth target voltage adjustment command, controlling the drive controller to control the corresponding converter to establish the nth target AC voltage. The adjustment sequence consists of sequentially arranged target AC voltage data from the first to the Nth target AC voltage data.

[0057] In some possible implementations, the adjustment sequence further includes: at least one power equalization control data; wherein, in the adjustment sequence, the nth target AC voltage data corresponds to and is adjacent to the qth power equalization control data in the at least one power equalization control data, and the nth target AC voltage data is set before the qth power equalization control data; q is a positive integer;

[0058] The first controller is also used to determine the q-th target power of each converter subarray based on the q-th power equalization control data in the adjustment sequence, and based on the q-th target power of each converter subarray, synchronously send the q-th power adjustment command carrying the corresponding q-th target power to the second controller set for each converter subarray, so that the second controller sends the q-th power output command to the drive controller connected in communication based on the received q-th power adjustment command, and controls the drive controller to control the corresponding converter to output the q-th target power.

[0059] In some possible implementations, the number of power equalization control data points in the adjustment sequence is the same as the number of target AC voltage data points; and the target AC voltage data points and power equalization control data points are alternately arranged in the adjustment sequence.

[0060] In some possible implementations, the number of power equalization control data in the adjustment sequence is less than the number of target AC voltage data; and, in the adjustment sequence, at least one target AC voltage data is set between two adjacent power equalization control data.

[0061] In some possible implementations, the main controller is further configured to acquire the power of the output port of each converter subarray, determine the average power of each converter subarray based on the power of the output port of each converter subarray and the number of converters in each converter subarray, and determine the determined average power of each converter subarray as the q-th target power of each converter subarray.

[0062] The working principle and specific implementation method of the main controller are the same as those of the first controller in the above embodiments. Therefore, the implementation method of the main controller can be referred to the specific implementation method of the first controller in the above embodiments, and will not be repeated here.

[0063] The technical effects of the corresponding solutions in the second aspect can be referenced from the technical effects that can be obtained by the solution corresponding to the first controller in the first aspect. The repetitions will not be described in detail.

[0064] Thirdly, embodiments of this application also provide a power system, which may include multiple DC sources, multiple first transformers, multiple control switches, multiple converter subarrays, a first AC bus, and a black-start controller; wherein, the multiple converter subarrays correspond one-to-one with the multiple DC sources and the multiple first transformers; one converter subarray in the multiple converter subarrays corresponds to at least one control switch in the multiple control switches. At least one converter subarray in the multiple converter subarrays includes at least one converter, the input port of each converter subarray in the multiple converter subarrays is connected to a DC source, and the output port of each converter subarray in the multiple converter subarrays is connected to the first AC bus through the first transformers and the control switches. The black-start controller is connected to the multiple converter subarrays. The black-start controller is used to sequentially execute the first to Nth voltage adjustment stages after the control switch is closed and the converters in each converter subarray are in the power-on state. Furthermore, during the nth voltage adjustment stage, it synchronously sends the nth target voltage adjustment command to each converter subarray, controlling each converter in the subarray to establish the nth target AC voltage. This nth target AC voltage is then converted by the first transformer into the nth target bus AC voltage input to the first AC bus. Here, n and N are integers greater than 1; 1 ≤ n ≤ N; the nth target AC voltage is greater than the (n-1)th target AC voltage; the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage; and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

[0065] In this application, the first AC bus can also be connected to other transformers or transmission lines to form a power grid or microgrid.

[0066] For example, the power system also includes a second transformer and a second AC bus, which are connected to transmission lines to form a power grid or microgrid. Thus, when the first AC bus has an nth target bus AC voltage, this nth target bus AC voltage is converted by the second transformer to generate an nth second bus AC voltage. Specifically, when the first AC bus has a 1st target bus AC voltage, this 1st target bus AC voltage is converted by the second transformer to generate a 1st second bus AC voltage. When the first AC bus has a 2nd target bus AC voltage, this 2nd target bus AC voltage is converted by the second transformer to generate a 2nd second bus AC voltage. When the first AC bus has a 3rd target bus AC voltage, this 3rd target bus AC voltage is converted by the second transformer to generate a 3rd second bus AC voltage. ...When the first AC bus has the Nth target bus AC voltage, the Nth target bus AC voltage is converted by the second transformer to generate the Nth second bus AC voltage, which is the rated voltage on the second AC bus.

[0067] The power system described in this application is applicable to scenarios such as photovoltaic power generation systems, energy storage power stations, and microgrids.

[0068] The technical effects of the corresponding solutions in the third aspect can be referenced from the technical effects that can be obtained by the corresponding solutions in the first aspect; the repetitions will not be detailed.

[0069] Fourthly, this application also provides a black-start control method based on multiple converter subarrays. At least one converter subarray in the multiple converter subarrays includes at least one converter. The input port of each converter subarray is connected to a DC source, and the output port of each converter subarray is connected to a first AC bus through a first transformer and a control switch. The black-start control method includes: after controlling the control switch to be closed and controlling the converter in each converter subarray to be in the power-on state, sequentially executing the working process of the first to Nth voltage adjustment stages; and, in the... During the nth voltage adjustment stage from the first voltage adjustment stage to the nth voltage adjustment stage within the Nth voltage adjustment stage, the nth target voltage adjustment command is synchronously sent to each converter subarray to control each converter in the converter subarray to establish the nth target AC voltage, so that the nth target AC voltage is converted into the nth target bus AC voltage input to the first AC bus via the first transformer; where n and N are integers greater than 1; 1≤n≤N, the nth target AC voltage is greater than the (n-1)th target AC voltage, the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

[0070] The technical effects of the corresponding solutions in the fourth aspect can be referenced from the technical effects that can be obtained by the corresponding solutions in the first aspect, and the repetitions will not be detailed. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of the structure of a power system provided in one embodiment of this application;

[0072] Figure 2 This is a schematic diagram of a voltage adjustment stage provided in one embodiment of this application;

[0073] Figure 3 This is a schematic diagram of the structure of a black start controller in a power system according to an embodiment of this application;

[0074] Figure 4 An interactive diagram illustrating a specific embodiment of the black-start control method provided in one embodiment of the present invention;

[0075] Figure 5 An interactive diagram illustrating a specific embodiment of the black-start control method provided in another embodiment of the present invention. Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "at least one" refers to one or more, where "multiple" refers to two or more. Therefore, in the embodiments of this application, "multiple" can also be understood as "at least two". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this application, words such as "first" and "second" are only used for distinguishing the purpose of description and should not be construed as indicating or implying relative importance or order.

[0077] It should be noted that in the embodiments of this application, "connection" refers to electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components, such as the connection between A and B. Alternatively, A can be directly connected to C, and C can be directly connected to B, with A and B connected through C. In the embodiments of this application, "coupling" can refer to the coupling between two windings through electromagnetic fields, that is, the transmission of electrical energy between the two windings through electromagnetic fields, mainly including the energy conversion process of electrical energy - magnetic potential energy - electrical energy.

[0078] It should be noted that the switch in the embodiments of this application can be one or more of various types of switching devices, such as relays, metal oxide semiconductor field effect transistors (MOSFETs), bipolar junction transistors (BJTs), insulated gate bipolar transistors (IGBTs), and silicon carbide (SiC) MOSFETs. These will not be listed individually in the embodiments of this application. Furthermore, each switch can include a first electrode, a second electrode, and a control electrode, wherein the control electrode is used to control the closing or opening of the switch. When the switch is closed, current can be transmitted between the first electrode and the second electrode. When the switch is open, no current can be transmitted between the first electrode and the second electrode. Taking a MOSFET as an example, the control electrode of the switch is the gate, the first electrode of the switch can be the source, and the second electrode can be the drain, or the first electrode can be the drain and the second electrode can be the source.

[0079] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0080] With rapid economic and social development, the installed capacity and load of the power system are constantly reaching new highs. Furthermore, the rapid development of ultra-high-voltage AC / DC transmission, large-scale wind power generation, photovoltaic power generation, and the extensive integration of microgrids into the grid have drastically changed the dynamic characteristics of the entire power system, bringing its operating point closer to its stability limit. Under these circumstances, the risk of large-scale power outages caused by power failures or improper operation is constantly increasing.

[0081] The economic and social impacts of a major power outage are highly correlated with the duration of the outage; the longer the outage, the more difficult the system recovery and the greater the losses. The recovery process after a power outage includes three stages: black start, grid restoration, and load restoration. The black start stage is fundamental to the entire recovery process, and its importance is self-evident. Because medium- and high-voltage transmission lines typically have large capacitive reactive loads during steady-state operation, often far exceeding the rated capacity of a single converter subarray, multiple converter subarrays need to start simultaneously during the black start stage to support the grid in establishing a stable voltage. However, when multiple converter subarrays in the grid differ in their location, construction phases, etc., resulting in inconsistencies in port impedance and communication delays with the upper-level controller, circulating currents can easily occur when simultaneously controlling the output voltage of multiple subarrays. This can lead to local overcurrent protection failures and black start failures, reducing the reliability of black start operations based on the coordinated operation of multiple converter subarrays. In this embodiment, the switches of each converter subarray are first closed to connect each converter subarray to the AC bus of the AC power grid that needs to be started. Then, the process of establishing the rated voltage of the AC bus is divided into multiple stages, and the voltage is increased by a certain amount in each stage. This process is repeated until the rated voltage is established. This solves the problem of subarray circulating current during the black start process of multiple converter subarrays in a power station or microgrid system, improves the reliability of grid black start, and enhances the applicability of multi-converter subarray coordinated black start, especially the black start scenario of transmission lines with large reactive power.

[0082] Reference Figure 1 , Figure 1 This is a schematic diagram of a power system provided in one embodiment of this application. The converter subarray in this application can have multiple subarrays, each containing one or more converters, depending on whether the converter technology used is centralized or string-type. There are multiple DC sources and multiple control switches. This application only illustrates three converter subarrays 20_1 to 20_3 as an example.

[0083] Reference Figure 1In some embodiments provided in this application, the power system includes: DC power sources 50_1 to 50_3, first transformers 40_1 to 40_3, control switches 321_1 to 322_3, converter subarrays 20_1 to 20_3, a first AC bus 60, and a black start controller 11. The converter subarrays 20_1 are correspondingly configured with the DC power sources 50_1, the first transformers 40_1, and the control switches 321_1 and 322_1. The input port of the converter subarrays 20_1 is connected to the DC power sources 50_1, the output port of the converter subarrays 20_1 is connected to the input terminal of the first transformers 40_1 via control switch 321_1, and the output terminal of the first transformers 40_1 is connected to the first AC bus 60 via control switch 322_1. Converter subarray 20_2 is configured correspondingly with DC source 50_2, first transformer 40_2, and control switches 321_2 and 322_2. The input port of converter subarray 20_2 is connected to DC source 50_2, and the output port of converter subarray 20_2 is connected to the input terminal of first transformer 40_2 via control switch 321_2. The output terminal of first transformer 40_2 is connected to first AC bus 60 via control switch 322_2. Converter subarray 20_3 is configured correspondingly with DC source 50_3, first transformer 40_3, and control switches 321_3 and 322_3. The input port of converter subarray 20_3 is connected to DC source 50_3, and the output port of converter subarray 20_3 is connected to the input terminal of first transformer 40_3 via control switch 321_3. The output terminal of first transformer 40_3 is connected to first AC bus 60 via control switch 322_3.

[0084] In this application, the first AC bus 60 can also be connected to other transformers or transmission lines to form a power grid or microgrid.

[0085] For example, refer to Figure 1The power system also includes a second transformer 70 and a second AC bus 80, which are connected to transmission lines to form a power grid or microgrid. When the first AC bus 60 has an nth target bus AC voltage, this nth target bus AC voltage is converted by the second transformer 70 to generate an nth second bus AC voltage. Specifically, when the first AC bus 60 has a first target bus AC voltage, this first target bus AC voltage is converted by the second transformer 70 to generate a first second bus AC voltage. When the first AC bus 60 has a second target bus AC voltage, this second target bus AC voltage is converted by the second transformer 70 to generate a second second bus AC voltage. When the first AC bus 60 has a third target bus AC voltage, this third target bus AC voltage is converted by the second transformer 70 to generate a third second bus AC voltage. ...When there is an Nth target bus AC voltage on the first AC bus 60, the Nth target bus AC voltage is converted by the second transformer 70 to generate the Nth second bus AC voltage, which is the rated voltage on the second AC bus 80.

[0086] The power system described in this application is applicable to scenarios such as photovoltaic power generation systems, energy storage power stations, and microgrids.

[0087] This application does not limit the specific structure of the converter subarray. For example, in this application, the converter subarray may include converters, monitors, etc. The converter may have a drive controller, which controls the switching frequency of the switches in the converter, enabling the converter to convert electrical energy from the DC source into AC power at power frequency (e.g., 50Hz).

[0088] This application does not limit the specific implementation of the DC source. For example, the DC source can be configured as an energy storage device, in which case the converter is an energy storage converter, the converter subarray is an energy storage converter subarray, and the energy storage converter can convert the electrical energy in the energy storage device into power frequency (e.g., 50Hz) AC power. Alternatively, the DC source can also be configured as a photovoltaic power generation device, in which case the converter is a photovoltaic converter, the converter subarray is a photovoltaic converter subarray, and the photovoltaic converter can convert the electrical energy in the photovoltaic power generation device into power frequency (e.g., 50Hz) AC power.

[0089] It should be noted that power frequency generally refers to the frequency of mains electricity. In my country, the power frequency is 50Hz, while other countries may use 60Hz. If the frequency of the power frequency AC is 50Hz, its power frequency period is 0.02 seconds.

[0090] Reference Figure 1The power system also includes a switch control module 12, and the first controller is also communicatively connected to the switch control module 12; wherein, the switch control module 12 is connected to control switches 321_1 to 322_3 respectively. The first controller is also used to send the identifier (e.g., ID) of each converter subarray in the plurality of converter subarrays to the switch control module, and the switch control module 12 is used to: firstly control the control switches 321_1 to 322_3 connected to the converter subarrays 20_1 to 20_3 to close, so that the output port of each converter in the converter subarray 20_1 is connected to the input terminal of the first transformer 40_1 in parallel, so that the output port of each converter in the converter subarray 20_2 is connected to the input terminal of the first transformer 40_2 in parallel, and so that the output port of each converter in the converter subarray 20_3 is connected to the input terminal of the first transformer 40_3 in parallel. Furthermore, the output terminals of the first transformers 40_1 to 40_3 are connected in parallel to the first AC bus 60. This allows the converters of each converter subarray and the AC power grid that needs to be started to be interconnected in the circuit.

[0091] For example, refer to Figure 1 The black-start controller 11 is used to sequentially execute the first to Nth voltage adjustment stages after controlling the control switches 321_1 to 322_3 are in the closed state and controlling the converters in each converter subarray 20_1 to 20_3 to be in the power-on state. Specifically, in the nth voltage adjustment stage, the nth target voltage adjustment command is synchronously sent to each converter subarray 20_1 to 20_3, controlling each converter in each converter subarray 20_1 to 20_3 to establish the nth target AC voltage, so that the nth target AC voltage is converted into the nth target bus AC voltage input to the first AC bus 60 via the corresponding first transformer.

[0092] For example, in the first voltage adjustment phase, the black-start controller 11 synchronously sends a first target voltage adjustment command to the converter subarrays 20_1 to 20_3. Each converter in the converter subarrays 20_1 to 20_3 can establish a first target AC voltage based on the first target voltage adjustment command. This first target AC voltage is then converted by the corresponding first transformers 40_1 to 40_3 and output as a first target bus AC voltage to the first AC bus 60. In the second voltage adjustment phase, the black-start controller 11 synchronously sends a second target voltage adjustment command to the converter subarrays 20_1 to 20_3. Each converter in the converter subarrays 20_1 to 20_3 can establish a second target AC voltage based on the second target voltage adjustment command. This second target AC voltage is then converted by the corresponding first transformers 40_1 to 40_3 and output as a second target bus AC voltage to the first AC bus 60. The same principle applies to the others, and so on, so I will not go into details here.

[0093] Furthermore, in this application, the second target AC voltage is greater than the first target AC voltage, the third target AC voltage is greater than the second target AC voltage, ..., the Nth target AC voltage is greater than the (N-1)th target AC voltage. Also, the second target bus AC voltage is greater than the first target bus AC voltage, the third target bus AC voltage is greater than the second target bus AC voltage, ..., the Nth target bus AC voltage is greater than the (N-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus 60.

[0094] In this embodiment, the process of establishing the rated voltage of the first AC bus 60 is divided into multiple stages. In each stage, the voltage is increased by a certain amount, and this process is repeated until the rated voltage is established, thereby helping the power grid establish voltage and restore the operation of the power system. This can solve the problem of circulating current in the subarray during the black start process of multiple converter subarrays in a power plant or microgrid system, improve the reliability of the power grid black start, and enhance the applicability of multi-converter subarray coordinated black start scenarios, especially the black start scenario of transmission lines with large reactive power.

[0095] For example, the black start controller 11 is also used to control the start-up of each converter in the converter subarray 20_1 to 20_3 so that each converter in the converter subarray 20_1 to 20_3 is already in a powered-on or available state before the black start is implemented.

[0096] Reference Figure 2 , Figure 2 This is a schematic diagram illustrating voltage adjustment stages according to an embodiment of this application. T1 represents the first voltage adjustment stage, T2 represents the second voltage adjustment stage, T3 represents the third voltage adjustment stage, ... T NLet t represent the Nth voltage adjustment stage, t1 represent the start time of the 1st voltage adjustment stage, t2 represent the start time of the 2nd voltage adjustment stage, t3 represent the start time of the 3rd voltage adjustment stage, and so on. N This represents the start time of the Nth voltage adjustment phase. From the first voltage adjustment phase T1 to the Nth voltage adjustment phase T... N In this system, there is an interval between the start times of any two adjacent voltage adjustment stages, and this interval is greater than one power frequency cycle. For example, the start time t2 of the second voltage adjustment stage T2 is separated from the start time t1 of the first voltage adjustment stage T1 by an interval of t2-t1, and t2-t1 is greater than one power frequency cycle. The start time t3 of the third voltage adjustment stage T3 is separated from the start time t2 of the second voltage adjustment stage T2 by an interval of t3-t2, and t3-t2 is greater than one power frequency cycle. ... The Nth voltage adjustment stage T... N The start time t N With the (N-1)th voltage regulation stage T N-1 The start time t N-1 There is an interval t between them N -t N-1 , and t N -t N-1 It is greater than one power frequency cycle.

[0097] For example, the time interval between the start times of any two adjacent voltage adjustment phases is the same. For instance, the intervals are t2-t1, t3-t2, ..., t... N -t N-1 same.

[0098] Optionally, the interval time is K times the power frequency period. For example, if K=2, then the interval time t2-t1, the interval time t3-t2, ..., the interval time t N -t N-1 Each is twice the power frequency cycle. Alternatively, if K = 3, then the intervals t2-t1, t3-t2, ..., t... N -t N-1 Each of these is three times the power frequency cycle. Alternatively, if K = 4, then the intervals t2-t1, t3-t2, ..., t... are all three times the power frequency cycle. N -t N-1 Each of these values ​​is four times the power frequency cycle. It should be noted that the specific value of K can be determined based on the actual application requirements and is not limited here.

[0099] In some examples, in the first to the Nth voltage adjustment stages, at least a portion of the voltage difference between the target AC voltages of any two adjacent voltage adjustment stages is the same. For example, in the first to the Nth voltage adjustment stages, at least a portion of the absolute values ​​of the voltage difference between the target AC voltages of any two adjacent voltage adjustment stages are the same.

[0100] For example, at least a portion of the absolute values ​​of the voltage difference between the target AC voltages in each adjacent two voltage adjustment stages can be the same. For instance, the absolute value of the voltage difference between the first and second target AC voltages is the same as the absolute value of the voltage difference between the second and third target AC voltages. The absolute value of the voltage difference between the second and third target AC voltages is the same as the absolute value of the voltage difference between the third and fourth target AC voltages. The absolute value of the voltage difference between the third and fourth target AC voltages is different from the absolute value of the voltage difference between the fourth and fifth target AC voltages. The absolute value of the voltage difference between the fourth and fifth target AC voltages is the same as the absolute value of the voltage difference between the fifth and sixth target AC voltages. The rest can be deduced similarly, and will not be elaborated further here.

[0101] For example, the voltage difference between the target AC voltages of any two adjacent voltage adjustment stages can also be made the same. For instance, the absolute values ​​of the voltage differences between the first and second target AC voltages, the second and third target AC voltages, the third and fourth target AC voltages, the fourth and fifth target AC voltages, and the fifth and sixth target AC voltages can all be the same. The rest can be deduced similarly and will not be elaborated upon here.

[0102] In other examples, the voltage difference between the target AC voltages of each adjacent voltage adjustment stage increases sequentially from the first to the Nth voltage adjustment stage. For example, the absolute value of the voltage difference between the target AC voltages of each adjacent voltage adjustment stage increases sequentially from the first to the Nth voltage adjustment stage. Exemplarily, the absolute value of the voltage difference between the first and second target AC voltages is less than the absolute value of the voltage difference between the second and third target AC voltages, the absolute value of the voltage difference between the second and third target AC voltages is less than the absolute value of the voltage difference between the third and fourth target AC voltages, the absolute value of the voltage difference between the third and fourth target AC voltages is less than the absolute value of the voltage difference between the fourth and fifth target AC voltages, and the absolute value of the voltage difference between the fifth and sixth target AC voltages is less than the absolute value of the voltage difference between the sixth and seventh target AC voltages. The rest can be deduced in the same way, and will not be elaborated here.

[0103] In some further examples, the voltage difference between the target AC voltages of each adjacent voltage adjustment stage decreases sequentially from the first to the Nth voltage adjustment stage. For example, the absolute value of the voltage difference between the target AC voltages of each adjacent voltage adjustment stage decreases sequentially from the first to the Nth voltage adjustment stage. Exemplarily, the absolute value of the voltage difference between the first and second target AC voltages is greater than the absolute value of the voltage difference between the second and third target AC voltages, the absolute value of the voltage difference between the second and third target AC voltages is greater than the absolute value of the voltage difference between the third and fourth target AC voltages, the absolute value of the voltage difference between the third and fourth target AC voltages is greater than the absolute value of the voltage difference between the fourth and fifth target AC voltages, and the absolute value of the voltage difference between the fifth and sixth target AC voltages is greater than the absolute value of the voltage difference between the sixth and seventh target AC voltages. The rest can be deduced in the same way, and will not be elaborated here.

[0104] Reference Figure 3 , Figure 3 This is a schematic diagram of the structure of a black-start controller in a power system according to one embodiment of this application. In this embodiment, the black-start controller 11 includes a first controller 111. The first controller 111 serves as an upper-level controller, also called a substation or power plant controller, or a microgrid controller, and is capable of controlling all converter subarrays to perform corresponding control functions.

[0105] The first controller provided in this application can be a master controller. Furthermore, the working principle and specific implementation of the master controller are the same as those of the first controller in this application. Therefore, the implementation of the master controller can be carried out by referring to the specific implementation of the first controller in this application, and will not be repeated here.

[0106] In a power system, a monitoring system can also be included. This system can monitor the active power, reactive power, voltage, current, frequency, and other parameters of the converter subarray. The first controller 111 can communicate with the monitoring system to obtain information such as the active power, reactive power, voltage, current, and frequency of the converter subarray from the monitoring system.

[0107] Reference Figure 3 In this embodiment of the application, the controller further includes second controllers 112_1 to 112_3. The first controller 111 and the second controllers 112_1 to 112_3 are communicatively connected. Exemplarily, the second controller 112_1 is configured correspondingly to the converter subarray 20_1, and is communicatively connected to the drive controller of the converter in the converter subarray 20_1. Similarly, the second controller 112_2 is configured correspondingly to the converter subarray 20_2, and is communicatively connected to the drive controller of the converter in the converter subarray 20_2. Finally, the second controller 112_3 is configured correspondingly to the converter subarray 20_3, and is communicatively connected to the drive controller of the converter in the converter subarray 20_3.

[0108] For example, the second controller 112_1 may be located in the same area as the converter subarray 20_1. For instance, the second controller 112_1 may be located within the operating area of ​​the converter subarray 20_1. The second controller 112_2 may be located in the same area as the converter subarray 20_2. For instance, the second controller 112_2 may be located within the operating area of ​​the converter subarray 20_2. The second controller 112_3 may be located in the same area as the converter subarray 20_3. For instance, the second controller 112_3 may be located within the operating area of ​​the converter subarray 20_3.

[0109] For example, the power system also includes an uninterrupted power supply (UPS), which is connected to both the switch control module and the second controller. The UPS stores electrical energy transmitted from the power grid before the power grid or electrical equipment is powered on, and provides the stored electrical energy to the switch control module and the second controller when the power grid or electrical equipment is powered off, thus achieving a black start. In actual use, the power system also includes a power module connected between the UPS and the switch control module and the second controller, through which the UPS can supply power to the switch control module and the second controller.

[0110] For example, the first controller 111, the second controllers 112_1 to 112_3, the drive controller, and the switch control module may each have a communication component for communicating with external devices or external servers. The communication component may include a WIFI module, a wired Ethernet communication protocol module, or other network communication protocol modules, so that the first controller 111 can communicate with external devices or external servers to exchange control signals and data signals.

[0111] Optionally, the communication component of the first controller 111 is communicatively connected to the communication components of the second controllers 112_1 to 112_3 and the switch control module, respectively, so that the first controller 111 communicates control signals and data signals with the second controllers 112_1 to 112_3 and the switch control module. The communication components of the second controllers 112_1 to 112_3 are communicatively connected to the communication component of the drive controller, so that the second controllers 112_1 to 112_3 and the drive controller communicate control signals and data signals.

[0112] In some examples, when black-start control is required, the operator inputs a black-start initiation command to the first controller 111. Upon receiving this command, the first controller 111 selects the converter subarrays 20_1 to 20_3 to participate in the black-start process and confirms that the selected subarrays are powered on or available. Then, it sends an initial black-start preparation command to the second controllers 112_1 to 112_3. Based on the received initial black-start preparation command, the second controllers 112_1 to 112_3 send target black-start preparation commands to the drive controllers of the converters in the subarrays 20_1 to 20_3. If the drive controllers of the converters in the subarrays 20_1 to 20_3 are ready, they send an initial black-start preparation completion command to the second controllers 112_1 to 112_3. Based on the initial black-start preparation completion command, the second controllers 112_1 to 112_3 send a target black-start preparation completion command to the first controller 111. After receiving the target black start preparation completion instruction, the first controller 111 can begin to execute the working process of the first voltage adjustment stage to the Nth voltage adjustment stage in sequence.

[0113] In other examples, the operator can also input a black-start initiation command to the first controller 111 through the upper-level controller. Upon receiving the command, the first controller 111 selects the converter subarrays 20_1 to 20_3 to participate in the black-start process and confirms that the selected subarrays are powered on or available. Then, it sends an initial black-start preparation command to the second controllers 112_1 to 112_3. Based on the received initial black-start preparation command, the second controllers 112_1 to 112_3 send target black-start preparation commands to the drive controllers of the converters in the subarrays 20_1 to 20_3. If the drive controllers of the converters in the subarrays 20_1 to 20_3 are ready, they send an initial black-start preparation completion command to the second controllers 112_1 to 112_3. Based on the initial black-start preparation completion command, the second controllers 112_1 to 112_3 send a target black-start preparation completion command to the first controller 111. After receiving the target black start preparation completion command, the first controller 111 can begin to sequentially execute the working process of the first to the Nth voltage adjustment stages. For example, the second controller can also be used to monitor the operating status information within the corresponding converter subarray, such as the voltage, current, frequency, and power (active power, reactive power) of the converters within the subarray. The first controller 111 can obtain information such as the voltage, current, frequency, and power (active power, reactive power) of the converter subarray from the second controller.

[0114] Reference Figure 3 The first controller 111 stores a pre-established adjustment sequence. This adjustment sequence consists of sequentially arranged target AC voltage data from the first target AC voltage data to the Nth target AC voltage data. For example, the adjustment sequence can be {U1, U2, U3, ... U...} N U1 represents the first target AC voltage data, U2 represents the second target AC voltage data, U3 represents the third target AC voltage data, ... U N This represents the AC voltage data of the Nth target.

[0115] In some examples, taking N=4 as an example, the adjustment sequence can be {U1, U2, U3, U4}. Specifically, U1 can be 0.25U4, U2 = 0.5U4, and U3 = 0.75U4, so the adjustment sequence can also be {0.25U4, 0.5U4, 0.75U4, U4}. Furthermore, 0.25U4 corresponds to establishing the first target AC voltage V1, 0.5U4 corresponds to establishing the second target AC voltage V2, 0.75U4 corresponds to establishing the third target AC voltage V3, and U4 corresponds to establishing the fourth target AC voltage V4, with V1 = 0.25V4, V2 = 0.5V4, and V3 = 0.75V4. Moreover, the fourth target AC voltage V4 corresponds to the output of the fourth target bus AC voltage to the first AC bus 60, which is the rated voltage of the first AC bus 60.

[0116] In other examples, taking N=4 as an example, the adjustment sequence can be {U1, U2, U3, U4}. Here, U1 can be 0.4U4, U2 = 0.6U4, and U3 = 0.8U4, so the adjustment sequence can also be {0.4U4, 0.6U4, 0.6U4, U4}. Furthermore, 0.4U4 corresponds to establishing the first target AC voltage V1, 0.6U4 corresponds to establishing the second target AC voltage V2, 0.8U4 corresponds to establishing the third target AC voltage V3, and U4 corresponds to establishing the fourth target AC voltage V4, with V1 = 0.4V4, V2 = 0.6V4, and V3 = 0.8V4. Moreover, the fourth target AC voltage V4 corresponds to the output of the fourth target bus AC voltage to the first AC bus 60, which is the rated voltage of the first AC bus 60.

[0117] This application does not limit the storage method of the first target AC voltage data to the Nth target AC voltage data. For example, the first target AC voltage data to the Nth target AC voltage data can be stored in the first controller 111 in binary, decimal or hexadecimal format.

[0118] Reference Figure 2 and Figure 3In this application, the first controller 111 is used to synchronously send a first target voltage adjustment command to the second controllers 112_1 to 112_3 based on the first target AC voltage data (e.g., 0.4U4) in a pre-established adjustment sequence during the first voltage adjustment stage. The second controllers 112_1 to 112_3 can then synchronously receive the first target voltage adjustment command. Specifically, the second controller 112_1 is used to send a first voltage output command to the drive controller in the converter subarray 20_1, which is communicatively connected to the first target AC voltage, based on the received first target voltage adjustment command. The drive controller in the converter subarray 20_1 is used to control the converter in the converter subarray 20_1 to convert the electrical energy of the DC source 50_1 into the first target AC voltage of the power frequency AC current, establishing the first target AC voltage V1, based on the received first voltage output command. Furthermore, the second controller 112_2 is used to send a first voltage output command to the drive controller in the converter subarray 20_2, which is communicatively connected to the first target voltage adjustment command, based on the received first target voltage adjustment command. The drive controller in the converter subarray 20_2, based on the received first voltage output command, controls the converter in the converter subarray 20_2 to convert the electrical energy from the DC source 50_2 into the first target AC voltage of the power frequency AC, establishing the first target AC voltage V1. And the second controller 112_3 is used to send a first voltage output command to the drive controller in the converter subarray 20_3, which is communicatively connected to the first target voltage adjustment command, based on the received first target voltage adjustment command. The drive controller in the converter subarray 20_3, based on the received first voltage output command, controls the converter in the converter subarray 20_3 to convert the electrical energy from the DC source 50_3 into the first target AC voltage of the power frequency AC, establishing the first target AC voltage V1.

[0119] The first controller 111, during the second voltage adjustment phase, synchronously sends a second target voltage adjustment command to the second controllers 112_1 to 112_3 based on the second target AC voltage data (e.g., 0.6U4) in a pre-established adjustment sequence. The second controllers 112_1 to 112_3 can then synchronously receive the second target voltage adjustment command. Specifically, the second controller 112_1, based on the received second target voltage adjustment command, sends a second voltage output command to the drive controller in the converter subarray 20_1, which is communicatively connected to it. The drive controller in the converter subarray 20_1, based on the received second voltage output command, controls the converter in the converter subarray 20_1 to convert the electrical energy from the DC source 50_1 into the second target AC voltage at power frequency, establishing the second target AC voltage V2. Furthermore, the second controller 112_2 is used to send a second voltage output command to the drive controller in the converter subarray 20_2, which is communicatively connected to the second target voltage adjustment command, based on the received second target voltage adjustment command. The drive controller in the converter subarray 20_2, based on the received second voltage output command, controls the converter in the converter subarray 20_2 to convert the electrical energy from the DC source 50_2 into the second target AC voltage of the power frequency AC, establishing the second target AC voltage V2. And, the second controller 112_3 is used to send a second voltage output command to the drive controller in the converter subarray 20_3, which is communicatively connected to the second target voltage adjustment command, based on the received second target voltage adjustment command. The drive controller in the converter subarray 20_3, based on the received second voltage output command, controls the converter in the converter subarray 20_3 to convert the electrical energy from the DC source 50_3 into the second target AC voltage of the power frequency AC, establishing the second target AC voltage V2.

[0120] The first controller 111, during the third voltage adjustment phase, synchronously sends a third target voltage adjustment command to the second controllers 112_1 to 112_3 based on the third target AC voltage data (e.g., 0.8U4) in a pre-established adjustment sequence. The second controllers 112_1 to 112_3 can then synchronously receive the third target voltage adjustment command. Specifically, the second controller 112_1, based on the received third target voltage adjustment command, sends a third voltage output command to the drive controller in the converter subarray 20_1, which is communicatively connected to it. The drive controller in the converter subarray 20_1, based on the received third voltage output command, controls the converter in the converter subarray 20_1 to convert the electrical energy from the DC source 50_1 into the third target AC voltage (power frequency AC), establishing the third target AC voltage V3. Furthermore, the second controller 112_2 is used to send a third voltage output command to the drive controller in the converter subarray 20_2, which is communicatively connected to the third target voltage adjustment command, based on the received third target voltage adjustment command. The drive controller in the converter subarray 20_2, based on the received third voltage output command, controls the converter in the converter subarray 20_2 to convert the electrical energy from the DC source 50_2 into the third target AC voltage of the power frequency AC, establishing the third target AC voltage V3. And, the second controller 112_3 is used to send a third voltage output command to the drive controller in the converter subarray 20_3, which is communicatively connected to the third target voltage adjustment command, based on the received third target voltage adjustment command. The drive controller in the converter subarray 20_3, based on the received third voltage output command, controls the converter in the converter subarray 20_3 to convert the electrical energy from the DC source 50_3 into the third target AC voltage of the power frequency AC, establishing the third target AC voltage V3.

[0121] The first controller 111, during the fourth voltage adjustment phase, synchronously sends a fourth target AC voltage adjustment command to the second controllers 112_1 to 112_3 based on the fourth target AC voltage data (e.g., U4) in a pre-established adjustment sequence. The second controllers 112_1 to 112_3 can then synchronously receive the fourth target AC voltage adjustment command. Specifically, the second controller 112_1, based on the received fourth target AC voltage adjustment command, sends a fourth voltage output command to the drive controller in the converter subarray 20_1, which is communicatively connected to it. The drive controller in the converter subarray 20_1, based on the received fourth voltage output command, controls the converter in the converter subarray 20_1 to convert the electrical energy from the DC source 50_1 into the fourth target AC voltage (power frequency AC), establishing the fourth target AC voltage V4. Furthermore, the second controller 112_2, based on the received fourth target AC voltage adjustment command, sends a fourth voltage output command to the drive controller in the converter subarray 20_2, which is communicatively connected to it. The drive controller in converter subarray 20_2, based on the received fourth voltage output command, controls the converters in converter subarray 20_2 to convert the electrical energy from DC source 50_2 into the fourth target AC voltage of power frequency AC, establishing the fourth target AC voltage V4. The second controller 112_3, based on the received fourth target voltage adjustment command, sends the fourth voltage output command to the drive controller in converter subarray 20_3, which is communicatively connected to it. The drive controller in converter subarray 20_3, based on the received fourth voltage output command, controls the converters in converter subarray 20_3 to convert the electrical energy from DC source 50_3 into the fourth target AC voltage of power frequency AC, establishing the fourth target AC voltage V4.

[0122] In some examples, each converter in each converter subarray is configured as a voltage-source converter.

[0123] For example, each converter in the converter subarray 20_1 is configured as a voltage-type converter. Furthermore, the second controller 112_1 synchronously sends the first voltage output command to the drive controller in each converter in the converter subarray 20_1, so that the drive controller in each converter in the converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter based on the received first voltage output command, thereby converting the electrical energy of the DC source 50_1 into the first target AC voltage of the power frequency AC, establishing the first target AC voltage V1. The process of the second controller 112_1 controlling the establishment of the remaining target AC voltages can be deduced similarly and will not be elaborated here.

[0124] For example, each converter in the converter subarray 20_2 is configured as a voltage-type converter. Furthermore, the second controller 112_2 synchronously sends the first voltage output command to the drive controller in each converter in the converter subarray 20_2, so that the drive controller in each converter in the converter subarray 20_2 controls the switching frequency of the switch in the corresponding converter based on the received first voltage output command, thereby converting the electrical energy of the DC source 50_2 into the first target AC voltage of the power frequency AC, establishing the first target AC voltage V1. The process of the second controller 112_2 controlling the establishment of the remaining target AC voltages can be deduced similarly and will not be elaborated here.

[0125] For example, each converter in the converter subarray 20_3 is configured as a voltage-type converter. Furthermore, the second controller 112_3 synchronously sends the first voltage output command to the drive controller in each converter in the converter subarray 20_3, so that the drive controller in each converter in the converter subarray 20_3 controls the switching frequency of the switch in the corresponding converter based on the received first voltage output command, thereby converting the electrical energy of the DC source 50_3 into the first target AC voltage of the power frequency AC, establishing the first target AC voltage V1. The process of the second controller 112_3 controlling the establishment of the remaining target AC voltages can be deduced similarly and will not be elaborated here.

[0126] In this embodiment, the drive controller of each converter in each converter subarray is further configured to, after controlling the corresponding converter to establish n target AC voltages, control the corresponding converter to correct the phase of the established nth target AC voltage based on the AC voltage at the output port of its respective converter subarray. For example, the drive controller is further configured to, after controlling the corresponding converter to establish the first target AC voltage V1, control the corresponding converter to correct the phase of the established first target AC voltage V1 based on the AC voltage at the output port of its respective converter subarray. The rest are similar and can be deduced sequentially, and will not be elaborated further here.

[0127] Reference Figure 4 , Figure 4 This is an interactive diagram illustrating a specific embodiment of the black-start control method provided in one embodiment of the present invention. Figure 4 The second controller 112_1 and the converter subarray 20_1 are used as examples for illustration.

[0128] Reference Figure 3 and Figure 4 The black start control method provided in this application embodiment may include the following steps:

[0129] S10. The operator can input a black start command to the first controller 111 through the upper-level controller. The first controller 111 can receive the black start command output by the upper-level controller and, after receiving the command, can select the converter subarrays participating in the black start, for example, subarrays 20_1 to 20_3. The first controller 111 sends the IDs of the selected converter subarrays 20_1 to 20_3 to the switch control module 12. The switch control module 12 controls the control switches 321_1 to 322_3 connected to the converter subarrays 20_1 to 20_3 to close, connecting the converters of the subarrays 20_1 to 20_3 and the AC power grid that needs to be started to operate in the circuit. Afterwards, the first controller 111 synchronously sends subarray start commands to the second controllers 112_1 to 112_3 corresponding to the converter subarrays 20_1 to 20_3.

[0130] Based on the received subarray start command, the second controller 112_1 sends a converter start-up command to the drive controller of each converter in the converter subarray 20_1. Each drive controller of each converter in the converter subarray 20_1 then controls the converter to start up based on the received start-up command, ensuring that each converter in the converter subarray 20_1 is in a powered-on or usable state before a black start is implemented.

[0131] Furthermore, based on the received subarray start command, the second controller 112_2 sends a converter start-up command to the drive controller of each converter in the converter subarray 20_2. The drive controller of each converter in the converter subarray 20_2 then controls the converter to start up based on the received converter start-up command, ensuring that each converter in the converter subarray 20_2 is in a powered-on or usable state before a black start is implemented.

[0132] Furthermore, the second controller 112_3, based on the received subarray start command, sends a converter power-on command to the drive controller of each converter in the converter subarray 20_3. The drive controller of each converter in the converter subarray 20_3, based on the received converter power-on command, controls the converter to power on, ensuring that each converter in the converter subarray 20_3 is in a powered-on or usable state before a black start is implemented.

[0133] S21, the first controller 111 sends an initial black start preparation command to the second controllers 112_1 to 112_3.

[0134] S22, the second controllers 112_1 to 112_3 send the target black start preparation command to the drive controller of the converter in the converter subarray 20_1 to 20_3 based on the received initial black start preparation command.

[0135] S23. If the drive controllers of the converters in the converter subarrays 20_1 to 20_3 are ready to complete, then send an initial black start preparation completion command to the second controllers 112_1 to 112_3.

[0136] S24. The second controllers 112_1 to 112_3 send a target black start preparation completion command to the first controller 111 based on the initial black start preparation completion command. After receiving the target black start preparation completion command, the first controller 111 can begin to execute the working process of the first voltage adjustment stage to the Nth voltage adjustment stage in sequence.

[0137] S31. During the first voltage adjustment phase, the first controller 111, based on the first target AC voltage data (e.g., 0.4U4) in the pre-established adjustment sequence, synchronously sends the first target voltage adjustment command to the second controllers 112_1 to 112_3. Then, the second controllers 112_1 to 112_3 can synchronously receive the first target voltage adjustment command.

[0138] S32, the second controller 112_1, based on the received first target voltage adjustment command, synchronously sends the first voltage output command to the drive controller in each converter in the converter subarray 20_1.

[0139] Furthermore, based on the received first target voltage adjustment command, the second controller 112_2 synchronously sends the first voltage output command to the drive controller in each converter in the converter subarray 20_2.

[0140] Furthermore, based on the received first target voltage adjustment command, the second controller 112_3 synchronously sends the first voltage output command to the drive controller in each converter in the converter subarray 20_3.

[0141] S33. In each converter in the converter subarray 20_1, the drive controller controls the switching frequency of the corresponding converter's switch based on the received first voltage output command, converting the electrical energy from the DC source 50_1 into the first target AC voltage V1 at the power frequency, thus establishing the first target AC voltage V1. The first target AC voltage V1 is then converted by the first transformer 40_1 and output to the first AC bus 60 as the first target bus AC voltage.

[0142] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the switching frequency of the corresponding converter's switch based on the received first voltage output command, thereby converting the electrical energy from the DC source 50_2 into the first target AC voltage V1 of the power frequency AC, establishing the first target AC voltage V1. The first target AC voltage V1 is then converted by the first transformer 40_2 and output to the first AC bus 60 as the first target bus AC voltage.

[0143] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the switching frequency of the corresponding converter's switch based on the received first voltage output command, thereby converting the electrical energy from the DC source 50_3 into the first target AC voltage V1 of the power frequency AC, establishing the first target AC voltage V1. The first target AC voltage V1 is then converted by the first transformer 40_3 and output to the first AC bus 60 as the first target bus AC voltage.

[0144] S34. The drive controller in each converter in the converter subarray 20_1 controls the corresponding converter to correct the phase of the established first target AC voltage V1 based on the AC voltage of the output port of the converter subarray.

[0145] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the corresponding converter to correct the phase of the established first target AC voltage V1 based on the AC voltage at the output port of the converter subarray.

[0146] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the corresponding converter to correct the phase of the established first target AC voltage V1 based on the AC voltage of the output port of the converter subarray in which it is located.

[0147] S41. During the second voltage adjustment phase, the first controller 111, based on the second target AC voltage data (e.g., 0.6U4) in the pre-established adjustment sequence, synchronously sends a second target voltage adjustment command to the second controllers 112_1 to 112_3. Then, the second controllers 112_1 to 112_3 can synchronously receive the second target voltage adjustment command.

[0148] S42, the second controller 112_1, based on the received second target voltage adjustment command, synchronously sends a second voltage output command to the drive controller in each converter in the converter subarray 20_1.

[0149] Furthermore, based on the received second target voltage adjustment command, the second controller 112_2 synchronously sends a second voltage output command to the drive controller in each converter in the converter subarray 20_2.

[0150] Furthermore, based on the received second target voltage adjustment command, the second controller 112_3 synchronously sends a second voltage output command to the drive controller in each converter in the converter subarray 20_3.

[0151] S43. Based on the received second voltage output command, the drive controller in each converter in the converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter, thereby converting the electrical energy of the DC source 50_1 into the second target AC voltage V2 of the power frequency AC, and establishing the second target AC voltage V2. The second target AC voltage V2 is then converted by the first transformer 40_1 and output to the first AC bus 60 as the second target bus AC voltage.

[0152] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the switching frequency of the corresponding converter's switch based on the received second voltage output command, thereby converting the electrical energy from the DC source 50_2 into the second target AC voltage V2 at the power frequency, thus establishing the second target AC voltage V2. The second target AC voltage V2 is then converted by the first transformer 40_2 and output as the second target bus AC voltage to the first AC bus 60.

[0153] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the switching frequency of the corresponding converter's switch based on the received second voltage output command, thereby converting the electrical energy from the DC source 50_3 into the second target AC voltage V2 at the power frequency, establishing the second target AC voltage V2. The second target AC voltage V2 is then converted by the first transformer 40_3 and output as the second target bus AC voltage to the first AC bus 60.

[0154] S44. The drive controller in each converter in the converter subarray 20_1 controls the corresponding converter to correct the phase of the established second target AC voltage V2 based on the AC voltage of the output port of the converter subarray.

[0155] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the corresponding converter to correct the phase of the established second target AC voltage V2 based on the AC voltage at the output port of the converter subarray.

[0156] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the corresponding converter to correct the phase of the established second target AC voltage V2 based on the AC voltage at the output port of the converter subarray.

[0157] S51, during the third voltage adjustment phase, the first controller 111, based on the third target AC voltage data (e.g., 0.8U4) in the pre-established adjustment sequence, synchronously sends the third target voltage adjustment command to the second controllers 112_1 to 112_3. Then, the second controllers 112_1 to 112_3 can synchronously receive the third target voltage adjustment command.

[0158] S52, the second controller 112_1, based on the received third target voltage adjustment command, synchronously sends a third voltage output command to the drive controller in each converter in the converter subarray 20_1.

[0159] Furthermore, based on the received third target voltage adjustment command, the second controller 112_2 synchronously sends a third voltage output command to the drive controller in each converter in the converter subarray 20_2.

[0160] Furthermore, based on the received third target voltage adjustment command, the second controller 112_3 synchronously sends a third voltage output command to the drive controller in each converter in the converter subarray 20_3.

[0161] S53. In each converter in the converter subarray 20_1, the drive controller controls the switching frequency of the corresponding converter's switch based on the received third voltage output command, thereby converting the electrical energy from the DC source 50_1 into the third target AC voltage V3 at power frequency, establishing the third target AC voltage V3. The third target AC voltage V3 is then converted by the first transformer 40_1 and output as the third target bus AC voltage to the first AC bus 60.

[0162] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the switching frequency of the corresponding converter's switch based on the received third voltage output command, thereby converting the electrical energy from the DC source 50_2 into the third target AC voltage V3 at the power frequency, thus establishing the third target AC voltage V3. The third target AC voltage V3 is then converted by the first transformer 40_2 and output as the third target bus AC voltage to the first AC bus 60.

[0163] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the switching frequency of the corresponding converter's switch based on the received third voltage output command, thereby converting the electrical energy from the DC source 50_3 into the third target AC voltage V3 at the power frequency, establishing the third target AC voltage V3. The third target AC voltage V3 is then converted by the first transformer 40_3 and output as the third target bus AC voltage to the first AC bus 60.

[0164] S54. The drive controller in each converter in the converter subarray 20_1 controls the corresponding converter to correct the phase of the established third target AC voltage V3 based on the AC voltage of the output port of the converter subarray.

[0165] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the corresponding converter to correct the phase of the established third target AC voltage V3 based on the AC voltage at the output port of the converter subarray.

[0166] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the corresponding converter to correct the phase of the established third target AC voltage V3 based on the AC voltage at the output port of the converter subarray.

[0167] S61. During the fourth voltage adjustment phase, the first controller 111, based on the fourth target AC voltage data (e.g., U4) in the pre-established adjustment sequence, synchronously sends the fourth target voltage adjustment command to the second controllers 112_1 to 112_3. Then, the second controllers 112_1 to 112_3 can synchronously receive the fourth target voltage adjustment command.

[0168] S62, the second controller 112_1, based on the received fourth target voltage adjustment command, synchronously sends the fourth voltage output command to the drive controller in each converter in the converter subarray 20_1.

[0169] Furthermore, based on the received fourth target voltage adjustment command, the second controller 112_2 synchronously sends the fourth voltage output command to the drive controller in each converter in the converter subarray 20_2.

[0170] Furthermore, based on the received fourth target voltage adjustment command, the second controller 112_3 synchronously sends a fourth voltage output command to the drive controller in each converter in the converter subarray 20_3.

[0171] S63. In each converter in the converter subarray 20_1, the drive controller controls the switching frequency of the corresponding converter's switch based on the received fourth voltage output command, thereby converting the electrical energy from the DC source 50_1 into the fourth target AC voltage V4 at power frequency, establishing the fourth target AC voltage V4. The fourth target AC voltage V4 is then converted by the first transformer 40_1 and output as the fourth target bus AC voltage to the first AC bus 60.

[0172] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the switching frequency of the corresponding converter's switch based on the received fourth voltage output command, thereby converting the electrical energy from the DC source 50_2 into the fourth target AC voltage V4 at the power frequency, thus establishing the fourth target AC voltage V4. The fourth target AC voltage V4 is then converted by the first transformer 40_2 and output as the fourth target bus AC voltage to the first AC bus 60.

[0173] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the switching frequency of the corresponding converter's switch based on the received fourth voltage output command, thereby converting the electrical energy from the DC source 50_3 into the fourth target AC voltage V4 at the power frequency, thus establishing the fourth target AC voltage V4. The fourth target AC voltage V4 is then converted by the first transformer 40_3 and output as the fourth target bus AC voltage to the first AC bus 60.

[0174] S64. The drive controller in each converter in the converter subarray 20_1 controls the corresponding converter to correct the phase of the established fourth target AC voltage V4 based on the AC voltage of the output port of the converter subarray.

[0175] Furthermore, the drive controller in each converter in the converter subarray 20_2 controls the corresponding converter to correct the phase of the established fourth target AC voltage V4 based on the AC voltage at the output port of the converter subarray.

[0176] Furthermore, the drive controller in each converter in the converter subarray 20_3 controls the corresponding converter to correct the phase of the established fourth target AC voltage V4 based on the AC voltage at the output port of the converter subarray.

[0177] In other embodiments of this application, modifications have been made to the implementation methods described in the above embodiments. The differences between this embodiment and the above embodiments are described below, while the similarities are not repeated here.

[0178] In this embodiment, the adjustment sequence also includes one or more power equalization control data. Furthermore, in the adjustment sequence, the nth target AC voltage data corresponds to and is adjacent to the qth power equalization control data, and the nth target AC voltage data is set before the qth power equalization control data. For example, taking an adjustment sequence including multiple power equalization control data as an example, if the adjustment sequence includes Q power equalization control data, then the adjustment sequence includes the 1st to the Qth power equalization control data. Q is an integer greater than 1, q is a positive integer, and 1 ≤ q ≤ Q.

[0179] In some examples, in the adjustment sequence, the number of power balance control data is the same as the number of target AC voltage data. Moreover, in the adjustment sequence, the target AC voltage data and the power balance control data are arranged alternately. That is, Q = N, and the adjustment sequence has: the 1st target AC voltage data, the 1st power balance control data, the 2nd target AC voltage data, the 2nd power balance control data, the 3rd target AC voltage data, the 3rd power balance control data,... the Nth target AC voltage data, the Qth power balance control data.

[0180] Exemplarily, the adjustment sequence can be {U1, Dp1, U2, Dp2, U3, Dp3,... U N , Dp Q}. Dp1 represents the 1st power balance control data, Dp2 represents the 2nd power balance control data, Dp3 represents the 3rd power balance control data,... Dp Q represents the Qth power balance control data.

[0181] For example, taking N = 4 as an example, the adjustment sequence can be {U1, Dp1, U2, Dp2, U3, Dp3, U4, Dp4}. Among them, it can be made that U1 = 0.25U4, U2 = 0.5U4, U3 = 0.75U4, then the adjustment sequence can also be {0.25U4, Dp1, 0.5U4, Dp2, 0.75U4, Dp3, U4, Dp4}.

[0182] For example, taking N = 4 as an example, the adjustment sequence can be {U1, Dp1, U2, Dp2, U3, Dp3, U4, Dp4}. Among them, it can be made that U1 = 0.4U4, U2 = 0.6U4, U3 = 0.8U, then the adjustment sequence can also be {0.4U4, Dp1, 0.6U4, Dp2, 0.6U4, Dp3, U4, Dp4}.

[0183] In other examples, in the adjustment sequence, the number of power balance control data is less than the number of target AC voltage data. Moreover, in the adjustment sequence, at least one target AC voltage data is set between two adjacent power balance control data. That is, Q < N, and the adjustment sequence can have: no power balance control data is set between some of the target AC voltage data.

[0184] Exemplarily, the adjustment sequence can be {U1, Dp1, U2, U3, Dp2, U4, U5, U6, Dp3, U7,... U N , Dp N}. Dp1 represents the 1st power balance control data, Dp2 represents the 2nd power balance control data, Dp3 represents the 3rd power balance control data,... Dp QThis represents the Qth power equalization control data.

[0185] For example, taking N=4 as an example, the adjustment sequence can be {U1, Dp1, U2, U3, Dp2, U4, Dp3}. Here, U1 can be 0.25U4, U2 = 0.5U4, and U3 = 0.75U4, then the adjustment sequence can also be {0.25U4, Dp1, 0.5U4, 0.75U4, Dp2, U4, Dp3}.

[0186] For example, taking N=4 as an example, the adjustment sequence can be {U1, Dp1, U2, U3, Dp2, U4, Dp3}. Here, U1 can be 0.4U4, U2 = 0.6U4, and U3 = 0.8U4, then the adjustment sequence can also be {0.4U4, Dp1, 0.6U4, 0.6U4, Dp2, U4, Dp3}.

[0187] It should be noted that whether or not the power balancing control is implemented at a certain stage should ensure that the power of each converter subarray does not exceed the safe range after the voltage rises in the next stage. Otherwise, power balancing control of the converter subarray should be implemented.

[0188] It should be noted that after the converters in each converter subarray complete the adjustment of the target AC voltage or target power, it is not necessary to report back to the first controller or the second controller. This reduces the repeated confirmation time between the first controller or the second controller and the converters in each converter subarray, and simplifies the complexity of black start control.

[0189] Reference Figure 3 In this embodiment, the adjustment sequence is {U1, Dp1, U2, Dp2, U3, Dp3, ... U...} N , Dp NFor example, the first controller 111 is also used to determine the first target power PM1_1 of converter subarray 20_1, the first target power PM1_2 of converter subarray 20_2, and the first target power PM1_3 of converter subarray 20_3 based on the first power equalization control data in the adjustment sequence. Based on the first target power PM1_1 of converter subarray 20_1, the first target power PM1_2 of converter subarray 20_2, and the first target power PM1_3 of converter subarray 20_3, the first controller 112_1 simultaneously sends a first power adjustment command carrying the first target power PM1_1 to the second controller 112_1, sends a first power adjustment command carrying the first target power PM1_2 to the second controller and 112_2, and sends a first power adjustment command carrying the first target power PM1_3 to the second controller and 112_3. Furthermore, the second controller 112_1 is also configured to send a first power output command to the drive controller in the converter subarray 20_1, which is communicatively connected, based on the received first power adjustment command carrying the first target power PM1_1. The drive controller in the converter subarray 20_1 is also configured to control the corresponding converter to output the first target power PM1_1 based on the received first power output command. Furthermore, the second controller 112_2 is also configured to send a first power output command to the drive controller in the converter subarray 20_2, which is communicatively connected, based on the received first power adjustment command carrying the first target power PM1_2. The drive controller in the converter subarray 20_2 is also configured to control the corresponding converter to output the first target power PM1_2 based on the received first power output command. Furthermore, the second controller 112_3 is also used to send a first power output command to the drive controller in the converter subarray 20_3, which is communicatively connected, based on the received first power adjustment command carrying the first target power PM1_3. The drive controller in the converter subarray 20_3 is also used to control the corresponding converter to output the first target power PM1_3 based on the received first power output command. In this way, after the converter establishes the first target AC voltage and performs phase correction in the first voltage adjustment stage, and before the start of the second voltage adjustment stage, the power balance between the converter subarrays can be controlled, which can solve problems such as load power imbalance.

[0190] It should be noted that the process by which the first controller 111 controls the power balance between each converter subarray based on other power balance control data in the adjustment sequence can be referred to the above description, and will not be repeated here.

[0191] In this embodiment, the first controller 111 is further used to obtain the power PM at the output port of the converter subarray 20_1. 0q_1, based on the power PM at the output port of converter subarray 20_1 0q Given the number of converters in converter subarray 20_1 (e.g., R1), determine the average power (i.e., PM) of converter subarray 20_1. 0q _1 / R1), and the determined average power of the converter subarray 20_1 (i.e. PM) 0q The power PM1_q of converter subarray 20_1 is determined as _1 / R1). Furthermore, the first controller 111 is further configured to acquire the power PM at the output port of converter subarray 20_2. 0q _2, based on the power PM at the output port of converter subarray 20_2 0q Given the number of converters in converter subarray 20_2 (e.g., R2), determine the average power (i.e., PM) of converter subarray 20_2. 0q _2 / R2), and the determined average power of the converter subarray 20_2 (i.e. PM) 0q The power PM2_q of the converter subarray 20_2 is determined as PM2_q (_2 / R2). Furthermore, the first controller 111 is further configured to acquire the power PM at the output port of the converter subarray 20_3. 0q _3, based on the power PM at the output port of converter subarray 20_3 0q Given the number of converters in converter subarray 20_3 (e.g., R3), determine the average power (i.e., PM) of converter subarray 20_3. 0q _3 / R3), and the determined average power of the converter subarray 20_3 (i.e. PM) 0q _3 / R3) is determined as the q-th target power PM3_q of converter subarray 20_3.

[0192] For example, the first controller 111 can obtain the power of the output port of each converter subarray from the monitoring system. Alternatively, the first controller 111 can also obtain the power of the output port of each converter subarray from the first controller 111 corresponding to each converter subarray.

[0193] Reference Figure 5 , Figure 5 An interactive diagram illustrating a specific embodiment of the black-start control method provided in another embodiment of the present invention. Figure 5 The second controller 112_1 and the converter subarray 20_1 are used as examples for illustration.

[0194] Reference Figure 3 and Figure 5 The black start control method provided in this application embodiment may include the following steps:

[0195] Steps S10 to S34 can be referred to the above description and will not be repeated here.

[0196] S35. Based on the first power equalization control data in the adjustment sequence, the first controller 111 determines the first target power PM1_1 of converter subarray 20_1, the first target power PM1_2 of converter subarray 20_2, and the first target power PM1_3 of converter subarray 20_3, and simultaneously sends the first power adjustment command carrying the first target power PM1_1 to the second controller 112_1, the first power adjustment command carrying the first target power PM1_2 to the second controller 112_2, and the first power adjustment command carrying the first target power PM1_3 to the second controller 112_3.

[0197] S36, the second controller 112_1 sends the first power output command to the drive controller in each converter in the converter subarray 20_1 based on the received first power adjustment command carrying the first target power PM1_1.

[0198] Furthermore, the second controller 112_2 sends a first power output command to the drive controller in each converter in the converter subarray 20_2 based on the received first power adjustment command carrying the first target power PM1_2.

[0199] Furthermore, the second controller 112_3 sends a first power output command to the drive controller in each converter in the converter subarray 20_3 based on the received first power adjustment command carrying the first target power PM1_3.

[0200] S37. The drive controller in the converter subarray 20_1 controls the corresponding converter to output the first target power PM1_1 based on the first power output command received.

[0201] Furthermore, the drive controller in the converter subarray 20_2 controls the corresponding converter to output the first target power PM1_2 based on the first power output command received.

[0202] Furthermore, the drive controller in the converter subarray 20_3 controls the corresponding converter to output the first target power PM1_3 based on the first power output command received.

[0203] Steps S41 to S44 can be referred to the above description and will not be repeated here.

[0204] S45. Based on the second power equalization control data in the adjustment sequence, the first controller 111 determines the second target power PM2_1 of converter subarray 20_1, the second target power PM2_2 of converter subarray 20_2, and the second target power PM2_3 of converter subarray 20_3, and simultaneously sends the second power adjustment command carrying the second target power PM2_1 to the second controller 112_1, the second power adjustment command carrying the second target power PM2_2 to the second controller 112_2, and the second power adjustment command carrying the second target power PM2_3 to the second controller 112_3.

[0205] S46. The second controller 112_1 sends a second power output command to the drive controller in each converter in the converter subarray 20_1 based on the received second power adjustment command carrying the second target power PM2_1.

[0206] Furthermore, based on the received second power adjustment command carrying the second target power PM2_2, the second controller 112_2 sends a second power output command to the drive controller in each converter in the converter subarray 20_2.

[0207] Furthermore, the second controller 112_3 sends a second power output command to the drive controller in each converter in the converter subarray 20_3 based on the received second power adjustment command carrying the second target power PM2_3.

[0208] S47. The drive controller in the converter subarray 20_1 controls the corresponding converter to output the second target power PM2_1 based on the received second power output command.

[0209] Furthermore, the drive controller in the converter subarray 20_2 controls the corresponding converter to output the second target power PM2_2 based on the received second power output command.

[0210] Furthermore, the drive controller in the converter subarray 20_3 controls the corresponding converter to output the second target power PM2_3 based on the received second power output command.

[0211] Steps S51 to S54 can be referred to the above description and will not be repeated here.

[0212] S55, the first controller 111 determines the third target power PM3_1 of converter subarray 20_1, the third target power PM3_2 of converter subarray 20_2, and the third target power PM3_3 of converter subarray 20_3 based on the third power equalization control data in the adjustment sequence, and simultaneously sends the third power adjustment command carrying the third target power PM3_1 to the second controller 112_1, the third power adjustment command carrying the third target power PM3_2 to the second controller 112_2, and the third power adjustment command carrying the third target power PM3_3 to the second controller 112_3.

[0213] S56, the second controller 112_1 sends a third power output command to the drive controller in each converter in the converter subarray 20_1 based on the received third power adjustment command carrying the third target power PM3_1.

[0214] Furthermore, based on the received third power adjustment command carrying the third target power PM3_2, the second controller 112_2 sends a third power output command to the drive controller in each converter in the converter subarray 20_2.

[0215] Furthermore, the second controller 112_3, based on the received third power adjustment command carrying the third target power PM3_3, sends a third power output command to the drive controller in each converter in the converter subarray 20_3.

[0216] S57, the drive controller in the converter subarray 20_1 controls the corresponding converter to output the third target power PM3_1 based on the received third power output command.

[0217] Furthermore, the drive controller in the converter subarray 20_2 controls the corresponding converter to output the third target power PM3_2 based on the received third power output command.

[0218] Furthermore, the drive controller in the converter subarray 20_3 controls the corresponding converter to output the third target power PM3_3 based on the received third power output command.

[0219] Steps S61 to S64 can be referred to the above description and will not be repeated here.

[0220] S65, the first controller 111 determines the fourth target power PM4_1 of converter subarray 20_1, the second target power PM4_2 of converter subarray 20_2, and the second target power PM4_3 of converter subarray 20_3 based on the fourth power equalization control data in the adjustment sequence, and simultaneously sends the fourth power adjustment command carrying the fourth target power PM4_1 to the second controller 112_1, the fourth power adjustment command carrying the fourth target power PM4_2 to the second controller 112_2, and the fourth power adjustment command carrying the fourth target power PM4_3 to the second controller 112_3.

[0221] S66, the second controller 112_1 sends a fourth power output command to the drive controller in each converter in the converter subarray 20_1 based on the received fourth power adjustment command carrying the fourth target power PM4_1.

[0222] Furthermore, based on the received fourth power adjustment command carrying the fourth target power PM4_2, the second controller 112_2 sends the fourth power output command to the drive controller in each converter in the converter subarray 20_2.

[0223] Furthermore, based on the received fourth power adjustment command carrying the fourth target power PM4_3, the second controller 112_3 sends the fourth power output command to the drive controller in each converter in the converter subarray 20_3.

[0224] S67, the drive controller in the converter subarray 20_1 controls the corresponding converter to output the fourth target power PM4_1 based on the received fourth power output command.

[0225] Furthermore, the drive controller in the converter subarray 20_2 controls the corresponding converter to output the fourth target power PM4_2 based on the received fourth power output command.

[0226] Furthermore, the drive controller in the converter subarray 20_3 controls the corresponding converter to output the fourth target power PM4_3 based on the received fourth power output command.

[0227] In some embodiments of this application, modifications have been made to the implementation methods described in the above embodiments. The differences between this embodiment and the above embodiments will be described below, while the similarities will not be repeated.

[0228] In this embodiment, each converter in each converter subarray is a voltage-source converter. Furthermore, one converter in each converter subarray is a master converter, and the remaining converters are slave converters. The second controller is further configured to send the nth voltage output command to the drive controller in the corresponding master converter of the converter subarray. The drive controller connected to the master converter is further configured to control the master converter to establish the nth target AC voltage based on the received nth voltage output command, and to send a slave voltage output command to the drive controller in the slave converter based on the received nth voltage output command. The drive controller in the slave converter is configured to control the slave converter to establish the nth target AC voltage based on the received slave voltage output command.

[0229] For example, refer to Figure 3 In converter subarray 20_1, one converter is the master converter, and the remaining converters are slave converters. The second controller 112_1 sends the nth voltage output command to the drive controller in the master converter of converter subarray 20_1. The drive controller connected to the master converter in converter subarray 20_1 is further used to control the master converter to establish the nth target AC voltage based on the received nth voltage output command, and to send a slave voltage output command to the drive controller in the slave converter of converter subarray 20_1 based on the received nth voltage output command. The drive controller in the slave converter of converter subarray 20_1 is used to control the slave converter to establish the nth target AC voltage based on the received slave voltage output command.

[0230] For example, refer to Figure 3 In converter subarray 20_2, one converter is the master converter, and the remaining converters are slave converters. The second controller 112_2 sends the nth voltage output command to the drive controller in the master converter of converter subarray 20_2. The drive controller connected to the master converter in converter subarray 20_2 is further used to control the master converter to establish the nth target AC voltage based on the received nth voltage output command, and to send a slave voltage output command to the drive controller in the slave converter of converter subarray 20_2 based on the received nth voltage output command. The drive controller in the slave converter of converter subarray 20_2 is used to control the slave converter to establish the nth target AC voltage based on the received slave voltage output command.

[0231] For example, refer to Figure 3In converter subarray 20_3, one converter is the master converter, and the remaining converters are slave converters. The second controller 112_3 sends the nth voltage output command to the drive controller in the master converter of converter subarray 20_3. The drive controller connected to the master converter in converter subarray 20_3 is further used to control the master converter to establish the nth target AC voltage based on the received nth voltage output command, and to send a slave voltage output command to the drive controller in the slave converter of converter subarray 20_3 based on the received nth voltage output command. The drive controller in the slave converter of converter subarray 20_3 is used to control the slave converter to establish the nth target AC voltage based on the received slave voltage output command.

[0232] An interaction diagram of a specific embodiment of the black-start control method provided in another embodiment of the present invention can be referred to. Figure 5 Steps S10-S31, S34-S41, S44-S51, S54-S61, and S64-S67 can be referred to the above description and will not be repeated here.

[0233] In this embodiment, step S32 is: the second controller 112_1 sends the first voltage output command to the drive controller in the main converter in the converter subarray 20_1 based on the received first target voltage adjustment command.

[0234] Furthermore, based on the received first target voltage adjustment command, the second controller 112_2 sends the first voltage output command to the drive controller in the main converter in the converter subarray 20_2.

[0235] Furthermore, the second controller 112_3 sends a first voltage output command to the drive controller in the main converter in the converter subarray 20_3 based on the received first target voltage adjustment command.

[0236] Step S33 is as follows: The drive controller in the main converter of converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter based on the received first voltage output command, thereby converting the electrical energy of DC source 50_1 into the first target AC voltage V1 of power frequency AC, and establishing the first target AC voltage V1. Furthermore, the main converter in converter subarray 20_1 sends a slave voltage output command to the drive controller in the slave converter in converter subarray 20_1 based on the received first voltage output command. The drive controller in the slave converter in converter subarray 20_1 controls the slave converter to establish the first target AC voltage V1 based on the received slave voltage output command. Finally, the first target AC voltage V1 is converted by the first transformer 40_1 and output as the first target bus AC voltage to the first AC bus 60.

[0237] Furthermore, based on the received first voltage output command, the drive controller in the main converter of converter subarray 20_2 controls the switching frequency of the corresponding switch in the converter, thereby converting the electrical energy from DC source 50_2 into the first target AC voltage V1 of power frequency AC, establishing the first target AC voltage V1. Also, based on the received first voltage output command, the main converter in converter subarray 20_2 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_2. Based on the received slave voltage output command, the drive controller in the slave converter of converter subarray 20_2 controls the slave converter to establish the first target AC voltage V1. Finally, the first target AC voltage V1, after being converted by the first transformer 40_2, is output as the first target bus AC voltage to the first AC bus 60.

[0238] Furthermore, the drive controller in the main converter of converter subarray 20_3, based on the received first voltage output command, controls the switching frequency of the switch in the corresponding converter, thereby converting the electrical energy of DC source 50_3 into the first target AC voltage V1 of power frequency AC, establishing the first target AC voltage V1. Also, the main converter in converter subarray 20_3, based on the received first voltage output command, sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_3. The drive controller in the slave converter of converter subarray 20_3, based on the received slave voltage output command, controls the slave converter to establish the first target AC voltage V1. Finally, the first target AC voltage V1, after being converted by the first transformer 40_3, is output as the first target bus AC voltage to the first AC bus 60.

[0239] Step S42 is as follows: The second controller 112_1 sends a second voltage output command to the drive controller in the main converter in the converter subarray 20_1 based on the received second target voltage adjustment command.

[0240] Furthermore, based on the received second target voltage adjustment command, the second controller 112_2 sends a second voltage output command to the drive controller in the main converter in the converter subarray 20_2.

[0241] Furthermore, the second controller 112_3 sends a second voltage output command to the drive controller in the main converter in the converter subarray 20_3 based on the received second target voltage adjustment command.

[0242] Step S43 is as follows: The drive controller in the main converter of converter subarray 20_1 controls the switching frequency of the corresponding switch in the converter based on the received second voltage output command, thereby converting the electrical energy of DC source 50_1 into the second target AC voltage V2 of power frequency AC, and establishing the second target AC voltage V2. Furthermore, the main converter in converter subarray 20_1 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_1 based on the received second voltage output command. The drive controller in the slave converter of converter subarray 20_1 controls the slave converter to establish the second target AC voltage V2 based on the received slave voltage output command. Finally, the second target AC voltage V2 is converted by the first transformer 40_1 and output as the second target bus AC voltage to the first AC bus 60.

[0243] Furthermore, based on the received second voltage output command, the drive controller in the main converter of converter subarray 20_2 controls the switching frequency of the corresponding switch in the converter, thereby converting the electrical energy from DC source 50_2 into the second target AC voltage V2 at power frequency, establishing the second target AC voltage V2. Also, based on the received second voltage output command, the main converter in converter subarray 20_2 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_2. Based on the received slave voltage output command, the drive controller in the slave converter of converter subarray 20_2 controls the slave converter to establish the second target AC voltage V2. Finally, the second target AC voltage V2, after being converted by the first transformer 40_2, is output as the second target bus AC voltage to the first AC bus 60.

[0244] Furthermore, the drive controller in the main converter of converter subarray 20_3, based on the received second voltage output command, controls the switching frequency of the switches in the corresponding converter, thereby converting the electrical energy from DC source 50_3 into the second target AC voltage V2 of power frequency AC, establishing the second target AC voltage V2. Also, the main converter in converter subarray 20_3, based on the received second voltage output command, sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_2. The drive controller in the slave converter of converter subarray 20_3, based on the received slave voltage output command, controls the slave converter to establish the second target AC voltage V2. Finally, the second target AC voltage V2, after being converted by the first transformer 40_3, is output as the second target bus AC voltage to the first AC bus 60.

[0245] Step S52 is as follows: The second controller 112_1 sends a third voltage output command to the drive controller in the main converter in the converter subarray 20_1 based on the received third target voltage adjustment command.

[0246] Furthermore, based on the received third target voltage adjustment command, the second controller 112_2 sends a third voltage output command to the drive controller in the main converter in the converter subarray 20_2.

[0247] Furthermore, the second controller 112_3 sends a third voltage output command to the drive controller in the main converter in the converter subarray 20_3 based on the received third target voltage adjustment command.

[0248] Step S53 is as follows: The drive controller in the main converter of converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter based on the received third voltage output command, thereby converting the electrical energy of DC source 50_1 into the third target AC voltage V3 of power frequency AC, and establishing the third target AC voltage V3. Furthermore, the main converter in converter subarray 20_1 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_1 based on the received third voltage output command. The drive controller in the slave converter of converter subarray 20_1 controls the slave converter to establish the third target AC voltage V3 based on the received slave voltage output command. Finally, the third target AC voltage V3 is converted by the first transformer 40_1 and output to the first AC bus 60 as the third target bus AC voltage.

[0249] Furthermore, based on the received third voltage output command, the drive controller in the main converter of converter subarray 20_2 controls the switching frequency of the corresponding switch in the converter, thereby converting the electrical energy from DC source 50_2 into the third target AC voltage V3 at power frequency, thus establishing the third target AC voltage V3. Also, based on the received third voltage output command, the main converter in converter subarray 20_2 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_2. Based on the received slave voltage output command, the drive controller in the slave converter of converter subarray 20_2 controls the slave converter to establish the third target AC voltage V3. Finally, the third target AC voltage V3, after being converted by the first transformer 40_2, is output as the third target bus AC voltage to the first AC bus 60.

[0250] Furthermore, based on the received third voltage output command, the drive controller in the main converter of converter subarray 20_3 controls the switching frequency of the switch in the corresponding converter, thereby converting the electrical energy from DC source 50_3 into the third target AC voltage V3 at power frequency, establishing the third target AC voltage V3. Also, based on the received third voltage output command, the main converter in converter subarray 20_3 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_3. Based on the received slave voltage output command, the drive controller in the slave converter of converter subarray 20_3 controls the slave converter to establish the third target AC voltage V3. Finally, the third target AC voltage V3, after being converted by the first transformer 40_3, is output as the third target bus AC voltage to the first AC bus 60.

[0251] Step S62 is as follows: The second controller 112_1 sends a fourth voltage output command to the drive controller in the main converter in the converter subarray 20_1 based on the received fourth target voltage adjustment command.

[0252] Furthermore, based on the received fourth target voltage adjustment command, the second controller 112_2 sends a fourth voltage output command to the drive controller in the main converter in the converter subarray 20_2.

[0253] Furthermore, based on the received fourth target voltage adjustment command, the second controller 112_3 sends a fourth voltage output command to the drive controller in the main converter in the converter subarray 20_3.

[0254] Step S63 is as follows: The drive controller in the main converter of converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter based on the received fourth voltage output command, thereby converting the electrical energy of DC source 50_1 into the fourth target AC voltage V4 of power frequency AC, and establishing the fourth target AC voltage V4. Furthermore, the main converter in converter subarray 20_1 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_1 based on the received fourth voltage output command. The drive controller in the slave converter of converter subarray 20_1 controls the slave converter to establish the fourth target AC voltage V4 based on the received slave voltage output command. Finally, the fourth target AC voltage V4 is converted by the first transformer 40_1 and output as the fourth target bus AC voltage to the first AC bus 60.

[0255] Furthermore, based on the received fourth voltage output command, the drive controller in the main converter of converter subarray 20_2 controls the switching frequency of the corresponding switch in the converter, thereby converting the electrical energy from DC source 50_2 into the fourth target AC voltage V4 at power frequency, thus establishing the fourth target AC voltage V4. Also, based on the received fourth voltage output command, the main converter in converter subarray 20_2 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_2. Based on the received slave voltage output command, the drive controller in the slave converter of converter subarray 20_2 controls the slave converter to establish the fourth target AC voltage V4. Finally, the fourth target AC voltage V4, after being converted by the first transformer 40_2, is output as the fourth target bus AC voltage to the first AC bus 60.

[0256] Furthermore, based on the received fourth voltage output command, the drive controller in the main converter of converter subarray 20_3 controls the switching frequency of the corresponding switch in the converter, thereby converting the electrical energy from DC source 50_3 into the fourth target AC voltage V4 at power frequency, thus establishing the fourth target AC voltage V4. Also, based on the received fourth voltage output command, the main converter in converter subarray 20_3 sends a slave voltage output command to the drive controller in the slave converter of converter subarray 20_3. Based on the received slave voltage output command, the drive controller in the slave converter of converter subarray 20_3 controls the slave converter to establish the fourth target AC voltage V4. Finally, the fourth target AC voltage V4, after being converted by the first transformer 40_3, is output as the fourth target bus AC voltage to the first AC bus 60.

[0257] In some embodiments of this application, modifications have been made to the implementation methods described in the above embodiments. The differences between this embodiment and the above embodiments will be described below, while the similarities will not be repeated.

[0258] In this embodiment, one converter in each converter subarray is a voltage-source converter, and the remaining converters are current-source converters. The second controller is further configured to send the nth voltage output command to the drive controller connected to the voltage-source converter.

[0259] For example, refer to Figure 3 In converter subarray 20_1, one converter is a voltage-source converter, and the remaining converters are current-source converters. The second controller 112_1 is further used to send the nth voltage output command to the drive controller connected to the voltage-source converter in converter subarray 20_1. The voltage at the output port of the current-source converter in converter subarray 20_1 can follow the voltage at the output port of the voltage-source converter.

[0260] For example, refer to Figure 3 In converter subarray 20_2, one converter is a voltage-source converter, and the remaining converters are current-source converters. The second controller 112_2 is further used to send the nth voltage output command to the drive controller connected to the voltage-source converter in converter subarray 20_2. The voltage at the output port of the current-source converter in converter subarray 20_2 can follow the voltage at the output port of the voltage-source converter.

[0261] For example, refer to Figure 3 In converter subarray 20_3, one converter is a voltage-source converter, and the remaining converters are current-source converters. The second controller 112_3 is further used to send the nth voltage output command to the drive controller connected to the voltage-source converter in converter subarray 20_3. The voltage at the output port of the current-source converter in converter subarray 20_3 can follow the voltage at the output port of the voltage-source converter.

[0262] An interaction diagram of a specific embodiment of the black-start control method provided in another embodiment of the present invention can be referred to. Figure 5 Steps S10-S31, S34-S41, S44-S51, S54-S61, and S64-S67 can be referred to the above description and will not be repeated here.

[0263] In this embodiment, step S32 is: the second controller 112_1 sends the first voltage output command to the drive controller in the voltage-type converter in the converter subarray 20_1 based on the received first target voltage adjustment command.

[0264] Furthermore, based on the received first target voltage adjustment command, the second controller 112_2 sends the first voltage output command to the drive controller in the voltage-type converter in the converter subarray 20_2.

[0265] Furthermore, the second controller 112_3 sends a first voltage output command to the drive controller in the voltage-source converter in the converter subarray 20_3 based on the received first target voltage adjustment command.

[0266] Step S33 is as follows: The drive controller in the voltage-source converter of the converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter based on the received first voltage output command, thereby converting the electrical energy of the DC source 50_1 into the first target AC voltage V1 of the power frequency AC, and establishing the first target AC voltage V1. Furthermore, the current-source converter in the converter subarray 20_1 outputs the first target AC voltage V1 accordingly. Finally, the first target AC voltage V1 is converted by the first transformer 40_1 and output to the first AC bus 60 as the first target bus AC voltage.

[0267] Furthermore, the drive controller in the voltage-source converter of converter subarray 20_2 controls the switching frequency of the corresponding converter's switch based on the received first voltage output command, thereby converting the electrical energy from DC source 50_2 into the first target AC voltage V1 of power frequency AC, establishing the first target AC voltage V1. The current-source converter in converter subarray 20_2 then outputs the first target AC voltage V1. Finally, the first target AC voltage V1 is converted by the first transformer 40_2 and output as the first target bus AC voltage to the first AC bus 60.

[0268] Furthermore, the drive controller in the voltage-source converter of the converter subarray 20_3 controls the switching frequency of the corresponding switch in the converter based on the received first voltage output command, thereby converting the electrical energy of the DC source 50_3 into the first target AC voltage V1 of the power frequency AC, establishing the first target AC voltage V1. The current-source converter in the converter subarray 20_3 then outputs the first target AC voltage V1. Finally, the first target AC voltage V1 is converted by the first transformer 40_3 and output as the first target bus AC voltage to the first AC bus 60.

[0269] Step S42 is as follows: The second controller 112_1 sends a second voltage output command to the drive controller in the voltage-type converter in the converter subarray 20_1 based on the received second target voltage adjustment command.

[0270] Furthermore, based on the received second target voltage adjustment command, the second controller 112_2 sends a second voltage output command to the drive controller in the voltage-type converter in the converter subarray 20_2.

[0271] Furthermore, the second controller 112_3 sends a second voltage output command to the drive controller in the voltage-type converter in the converter subarray 20_3 based on the received second target voltage adjustment command.

[0272] Step S43 is as follows: Based on the received second voltage output command, the drive controller in the voltage-source converter of the converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter, thereby converting the electrical energy of the DC source 50_1 into the second target AC voltage V2 of the power frequency AC, and establishing the second target AC voltage V2. Furthermore, the current-source converter in the converter subarray 20_1 outputs the second target AC voltage V2 accordingly. Finally, the second target AC voltage V2 is converted by the first transformer 40_1 and output to the first AC bus 60 as the second target bus AC voltage.

[0273] Furthermore, the drive controller in the voltage-source converter of converter subarray 20_2 controls the switching frequency of the corresponding switch in the converter based on the received second voltage output command, thereby converting the electrical energy of DC source 50_2 into the second target AC voltage V2 of power frequency AC, establishing the second target AC voltage V2. The current-source converter in converter subarray 20_2 then outputs the second target AC voltage V2. Finally, the second target AC voltage V2 is converted by the first transformer 40_2 and output as the second target bus AC voltage to the first AC bus 60.

[0274] Furthermore, the drive controller in the voltage-source converter of the converter subarray 20_3 controls the switching frequency of the corresponding switch in the converter based on the received second voltage output command, thereby converting the electrical energy of the DC source 50_3 into the second target AC voltage V2 of the power frequency AC, establishing the second target AC voltage V2. The current-source converter in the converter subarray 20_3 then outputs the second target AC voltage V2. Finally, the second target AC voltage V2 is converted by the first transformer 40_3 and output as the second target bus AC voltage to the first AC bus 60.

[0275] Step S52 is as follows: The second controller 112_1 sends a third voltage output command to the drive controller in the main voltage type converter in the converter subarray 20_1 based on the received third target voltage adjustment command.

[0276] Furthermore, based on the received third target voltage adjustment command, the second controller 112_2 sends a third voltage output command to the drive controller in the voltage-type converter in the converter subarray 20_2.

[0277] Furthermore, the second controller 112_3 sends a third voltage output command to the drive controller in the voltage-source converter in the converter subarray 20_3 based on the received third target voltage adjustment command.

[0278] Step S53 is as follows: Based on the received third voltage output command, the drive controller in the voltage-source converter of the converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter, thereby converting the electrical energy of the DC source 50_1 into the third target AC voltage V3 of the power frequency AC, and establishing the third target AC voltage V3. Furthermore, the current-source converter in the converter subarray 20_1 outputs the third target AC voltage V3 accordingly. Finally, the third target AC voltage V3 is converted by the first transformer 40_1 and output to the first AC bus 60 as the third target bus AC voltage.

[0279] Furthermore, the drive controller in the voltage-source converter of converter subarray 20_2 controls the switching frequency of the corresponding switch in the converter based on the received third voltage output command, thereby converting the electrical energy of DC source 50_2 into the third target AC voltage V3 of power frequency AC, establishing the third target AC voltage V3. The current-source converter in converter subarray 20_2 then outputs the third target AC voltage V3. Finally, the third target AC voltage V3 is converted by the first transformer 40_2 and output as the third target bus AC voltage to the first AC bus 60.

[0280] Furthermore, the drive controller in the voltage-source converter of converter subarray 20_3 controls the switching frequency of the corresponding switch in the converter based on the received third voltage output command, thereby converting the electrical energy of DC source 50_3 into the third target AC voltage V3 of power frequency AC, establishing the third target AC voltage V3. The current-source converter in converter subarray 20_3 then outputs the third target AC voltage V3. Finally, the third target AC voltage V3 is converted by the first transformer 40_3 and output as the third target bus AC voltage to the first AC bus 60.

[0281] Step S62 is as follows: The second controller 112_1 sends a fourth voltage output command to the drive controller in the voltage-type converter in the converter subarray 20_1 based on the received fourth target voltage adjustment command.

[0282] Furthermore, based on the received fourth target voltage adjustment command, the second controller 112_2 sends a fourth voltage output command to the drive controller in the voltage-source converter in the converter subarray 20_2.

[0283] Furthermore, the second controller 112_3 sends a fourth voltage output command to the drive controller in the voltage-source converter in the converter subarray 20_3 based on the received fourth target voltage adjustment command.

[0284] Step S63 is as follows: Based on the received fourth voltage output command, the drive controller in the voltage-source converter of the converter subarray 20_1 controls the switching frequency of the switch in the corresponding converter, thereby converting the electrical energy of the DC source 50_1 into the fourth target AC voltage V4 of the power frequency AC, and establishing the fourth target AC voltage V4. Furthermore, the current-source converter in the converter subarray 20_1 outputs the fourth target AC voltage V4 accordingly. Finally, the fourth target AC voltage V4 is converted by the first transformer 40_1 and output to the first AC bus 60 as the fourth target bus AC voltage.

[0285] Furthermore, based on the received fourth voltage output command, the drive controller in the voltage-source converter of converter subarray 20_2 controls the switching frequency of the corresponding switch in the converter, thereby converting the electrical energy from DC source 50_2 into the fourth target AC voltage V4 at power frequency, establishing the fourth target AC voltage V4. The current-source converter in converter subarray 20_2 then outputs the fourth target AC voltage V4. Finally, the fourth target AC voltage V4 is converted by the first transformer 40_2 and output as the fourth target bus AC voltage to the first AC bus 60.

[0286] Furthermore, the drive controller in the voltage-source converter of converter subarray 20_3 controls the switching frequency of the corresponding switch in the converter based on the received fourth voltage output command, thereby converting the electrical energy of DC source 50_3 into the fourth target AC voltage V4 of power frequency AC, establishing the fourth target AC voltage V4. The current-source converter in converter subarray 20_3 then outputs the fourth target AC voltage V4. Finally, the fourth target AC voltage V4 is converted by the first transformer 40_3 and output as the fourth target bus AC voltage to the first AC bus 60.

[0287] In some embodiments of this application, modifications have been made to the implementation methods described in the above embodiments. The differences between this embodiment and the above embodiments will be described below, while the similarities will not be repeated.

[0288] In this embodiment, the switch control module can also be used to: first, control the closing of the control switch connecting the first part of the converter subarrays in the multiple converter subarrays, so that the output port of each converter in each converter subarray in the first part of the converter subarray is connected to the input terminal of the corresponding transformer in parallel, and the output terminal of the transformer corresponding to the first part of the converter subarray is connected to the first AC bus. Then, a start command is sent to each converter subarray in the first part of the converter subarray to control each converter subarray in the first part of the converter subarray to start up, so that each converter in the first part of the converter subarray is in a powered-on or usable state before a black start is performed. Then, control the closing of the control switch connecting the second part of the multiple converter subarrays, so that the output port of each converter in each converter subarray in the second part of the converter subarray is connected to the input terminal of the corresponding transformer in parallel, and the output terminal of the transformer corresponding to the second part of the converter subarray is connected to the first AC bus. Then, a start command is sent to each converter subarray in the second part of the converter subarray to control each converter subarray in the second part of the converter subarray to start up, so that each converter in the second part of the converter subarray is in a powered-on or available state before the black start is implemented.

[0289] In this embodiment, refer to Figure 3 The first controller 111 is further configured to synchronously send an initial voltage adjustment command to the second controller corresponding to each converter subarray in the first part of the converter subarray after controlling the power-on of each converter subarray in the first part of the converter subarray, and before closing the control switch connecting the second part of the converter subarrays in the plurality of converter subarrays. The second controller corresponding to each converter subarray in the first part of the converter subarray is further configured to send an initial voltage output command to the drive controller connected in communication based on the received initial voltage adjustment command. The drive controller in each converter subarray in the first part of the converter subarray is further configured to control the corresponding converter to establish an initial AC voltage based on the received initial voltage output command, so that the initial AC voltage is converted by the first transformer into an initial bus AC voltage input to the first AC bus 60. The initial bus AC voltage is less than the first target bus AC voltage.

[0290] In this embodiment, the first part of the converter subarray first establishes the initial bus AC voltage on the first AC bus 60. Then, after the remaining converter subarrays are connected to the grid, the first part of the converter subarray and the second part of the converter subarray are combined to increase the voltage on the first AC bus 60 in stages and implement power balancing control until the rated voltage is established on the first AC bus 60.

[0291] In this application, the number of converter subarrays in the first portion of the converter subarray is less than the number of converter subarrays in the second portion of the converter subarray. For example, the first portion of the converter subarray includes one of a plurality of converter subarrays, and the second portion of the converter subarray includes the remaining converter subarrays from the plurality of converter subarrays excluding the first portion. For example, refer to... Figure 3 The first part of the converter subarray may include converter subarray 20_1, and the second part of the converter subarray may include converter subarrays 20_2 and 20_3.

[0292] An interaction diagram of a specific embodiment of the black-start control method provided in another embodiment of the present invention can be referred to. Figure 5 Steps S21 to S67 can be referred to the above description and will not be repeated here.

[0293] In this embodiment, step S10 is as follows: The operator can input a black start command to the first controller 111 through the upper-level controller. The first controller 111 can receive the black start command output by the upper-level controller and, after receiving the command, can select the converter subarrays participating in the black start, for example, subarrays 20_1 to 20_3. The first controller 111 sends the IDs of the selected converter subarrays 20_1 to 20_3 to the switch control module 12. The switch control module 12 controls the control switches 321_1 and 322_1 connected to the converter subarray 20_1 to close, so that the output port of each converter in the converter subarray 20_1 is connected in parallel to the input terminal of the first transformer 40_1, and the output terminal of the first transformer 40_1 is connected to the first AC bus 60. This enables the converters of the converter subarray 20_1 and the AC power grid that needs to be started to be interconnected in the circuit.

[0294] Then, the first controller 111 sends a subarray start command to the second controller 112_1 corresponding to the converter subarray 20_1.

[0295] Subsequently, the second controller 112_1, based on the received subarray start command, sends a converter power-on command to the drive controller of each converter in the converter subarray 20_1. The drive controller of each converter in the converter subarray 20_1 then controls the converter to power on based on the received converter power-on command, ensuring that each converter in the converter subarray 20_1 is in a powered-on or usable state before a black start is implemented.

[0296] Then, the first controller 111 sends an initial voltage adjustment command to the second controller 112_1.

[0297] Subsequently, the second controller 112_1 sends an initial voltage output command to the drive controller of each converter in the converter subarray 20_1 based on the received initial voltage adjustment command.

[0298] Subsequently, the drive controller of each converter in the converter subarray 20_1 controls the corresponding converter to establish an initial AC voltage based on the received initial voltage output command, so that the initial AC voltage is converted into an initial bus AC voltage input to the first AC bus 60 by the first transformer 40_1.

[0299] Subsequently, the switch control module 12 controls the control switches 321_2, 322_2, 321_3, and 322_3 connected to the converter subarrays 20_2 to 20_3 to close. This causes the output ports of each converter in the converter subarray 20_2 to be connected in parallel to the input terminal of the first transformer 40_2, and the output ports of each converter in the converter subarray 20_3 to be connected in parallel to the input terminal of the first transformer 40_3. Furthermore, the output terminals of the first transformers 40_2 and 40_3 are connected in parallel to the first AC bus 60. This enables the converters in each converter subarray and the AC power grid requiring startup to be interconnected in the circuit. Afterward, the first controller 111 synchronously sends subarray start commands to the second controllers 112_2 to 112_3 corresponding to the converter subarrays 20_2 to 20_3.

[0300] Based on the received subarray start command, the second controller 112_2 sends a converter start-up command to the drive controller of each converter in the converter subarray 20_2. Each drive controller of each converter in the converter subarray 20_2 then controls the converter to start up based on the received start-up command, ensuring that each converter in the converter subarray 20_2 is in a powered-on or usable state before a black start is implemented.

[0301] Furthermore, the second controller 112_3, based on the received subarray start command, sends a converter power-on command to the drive controller of each converter in the converter subarray 20_3. The drive controller of each converter in the converter subarray 20_3, based on the received converter power-on command, controls the converter to power on, ensuring that each converter in the converter subarray 20_3 is in a powered-on or usable state before a black start is implemented.

[0302] This application embodiment also provides a black-start control method based on multiple converter subarrays. The black-start control method includes: after controlling the control switch to be closed and controlling the converters in each converter subarray to be in the power-on state, sequentially executing the working process of the first to the Nth voltage adjustment stages; and, within the nth voltage adjustment stage of the first to Nth voltage adjustment stages, synchronously sending the nth target voltage adjustment command to each converter subarray, controlling each converter in the converter subarray to establish the nth target AC voltage, so that the nth target AC voltage is converted by the first transformer into the nth target bus AC voltage input to the first AC bus; wherein n and N are integers greater than 1; 1≤n≤N, the nth target AC voltage is greater than the (n-1)th target AC voltage, the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

[0303] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0304] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A black-start controller based on multiple converter subarrays, characterized in that, At least one of the plurality of converter subarrays includes at least one converter, the input port of each of the plurality of converter subarrays is connected to a DC source, and the output port of each of the plurality of converter subarrays is connected to a first AC bus through a first transformer and a control switch. The black start controller includes: a first controller and multiple second controllers, wherein the multiple second controllers are connected one-to-one with the multiple converter subarrays; The first controller is configured to sequentially execute the working process of the first voltage adjustment stage to the Nth voltage adjustment stage after controlling the control switch to be in the closed state and controlling the converter in each of the converter subarrays to be in the power-on state; and, in the nth voltage adjustment stage among the first voltage adjustment stage to the Nth voltage adjustment stage, synchronously send the nth target voltage adjustment command to each of the plurality of second controllers, controlling each second controller to drive the converter subarray connected to it to output the nth target AC voltage, and the nth target AC voltage is converted into the nth target bus AC voltage input to the first AC bus by the first transformer; Wherein, n and N are integers greater than 1; 2≤n≤N, the nth target AC voltage is greater than the (n-1)th target AC voltage, the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

2. The black start controller as described in claim 1, characterized in that, Each converter in the converter subarray has a drive controller, and the second controller is communicatively connected to the drive controller of the corresponding converter in the converter subarray. The first controller is configured to, within the nth voltage adjustment stage, synchronously send the nth target AC voltage adjustment command to each of the plurality of second controllers based on the nth target AC voltage data in a pre-established adjustment sequence; wherein, the adjustment sequence has the first target AC voltage data to the Nth target AC voltage data arranged in sequence; Any one of the plurality of second controllers is used to send an nth voltage output command to the drive controller connected in communication, based on the received nth target voltage adjustment command; The drive controller is used to control the corresponding converter to establish the nth target AC voltage based on the received nth voltage output command.

3. The black-start controller as described in claim 2, characterized in that, The adjustment sequence further includes at least one power equalization control data; wherein, in the adjustment sequence, the nth target AC voltage data corresponds to and is adjacent to the qth power equalization control data in the at least one power equalization control data, and the nth target AC voltage data is set before the qth power equalization control data; q is a positive integer; The first controller is further configured to determine the qth target power of each converter subarray based on the qth power equalization control data in the adjustment sequence, and synchronously send a qth power adjustment command carrying the corresponding qth target power to the second controller set for each converter subarray based on the qth target power of each converter subarray. The second controller is also configured to send a q-th power output command to the drive controller connected in communication based on the received q-th power adjustment command; The drive controller is also configured to control the corresponding converter to output the q-th target power based on the received q-th power output command.

4. The black start controller as described in claim 3, characterized in that, In the adjustment sequence, the number of power equalization control data is the same as the number of target AC voltage data; and in the adjustment sequence, the target AC voltage data and the power equalization control data are arranged alternately. Alternatively, in the adjustment sequence, the number of power equalization control data is less than the number of target AC voltage data; and in the adjustment sequence, at least one target AC voltage data is set between two adjacent power equalization control data.

5. The black start controller as described in claim 3 or 4, characterized in that, The first controller is further configured to acquire the power of the output port of each converter subarray, determine the average power of each converter subarray based on the power of the output port of each converter subarray and the number of converters in each converter subarray, and determine the determined average power of each converter subarray as the qth target power of each converter subarray.

6. The black start controller as described in any one of claims 2-5, characterized in that, The drive controller is further configured to, after the corresponding converter establishes the nth target AC voltage, control the corresponding converter to correct the phase of the established nth target AC voltage based on the AC voltage at the output port of the converter subarray it belongs to.

7. The black start controller as described in any one of claims 2-6, characterized in that, Each converter in each of the converter subarrays is a voltage-type converter; and the second controller is further configured to synchronously send the nth voltage output command to the drive controller in each of the corresponding converter subarrays. Alternatively, each converter in each converter subarray is a voltage-type converter; and one converter in each converter subarray is a master converter, while the remaining converters are slave converters; the second controller is further configured to send the nth voltage output command to the drive controller in the corresponding master converter in the converter subarray; the drive controller connected to the master converter is further configured to control the master converter to establish the nth target AC voltage based on the received nth voltage output command, and to send a slave voltage output command to the drive controller in the slave converter based on the received nth voltage output command; The drive controller in the slave converter is used to control the slave converter to establish the nth target AC voltage based on the received slave voltage output command. Alternatively, in each of the converter subarrays, one converter is a voltage-source converter and the remaining converters are current-source converters; and the second controller is further configured to send the nth voltage output command to the drive controller connected to the voltage-source converter.

8. The black start controller as described in any one of claims 1-7, characterized in that, In the first to the Nth voltage adjustment stages, there is an interval between the start times of each two adjacent voltage adjustment stages, and the interval is greater than one power frequency cycle.

9. A main controller based on multiple converter subarrays, characterized in that, At least one of the plurality of converter subarrays includes at least one converter, the input port of each of the plurality of converter subarrays is connected to a DC source, and the output port of each of the plurality of converter subarrays is connected to a first AC bus through a first transformer and a control switch. The main controller is communicatively connected to multiple second controllers, and the multiple second controllers are configured one-to-one with the multiple converter subarrays. The second controller is used to control the operation of the corresponding converter subarray. The main controller is used to sequentially execute the first to Nth voltage adjustment stages after controlling the control switch to be closed and controlling the converters in each converter subarray to be powered on. Furthermore, during the nth voltage adjustment stage (from the first to the Nth voltage adjustment stages), the main controller synchronously sends an nth target voltage adjustment command to each second controller, so that each second controller controls its corresponding converter subarray to establish the nth target AC voltage. The nth target AC voltage is then converted by the first transformer into the nth target bus AC voltage input to the first AC bus. Wherein, n and N are integers greater than 1; 2≤n≤N, the nth target AC voltage is greater than the (n-1)th target AC voltage, the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

10. The main controller as described in claim 9, characterized in that, Each converter in the converter subarray has a drive controller, and the second controller is communicatively connected to the drive controller of the corresponding converter in the converter subarray. The main controller is used to synchronously send the nth target AC voltage adjustment command to each of the second controllers during the nth voltage adjustment stage, based on the nth target AC voltage data in the pre-established adjustment sequence. This causes the second controller to send the nth voltage output command to the drive controller connected in communication based on the received nth target AC voltage adjustment command, thereby controlling the drive controller to control the corresponding converter to establish the nth target AC voltage. The adjustment sequence consists of target AC voltage data from the first target AC voltage to the Nth target AC voltage data arranged in sequence.

11. The main controller as described in claim 10, characterized in that, The adjustment sequence further includes at least one power equalization control data; wherein, in the adjustment sequence, the nth target AC voltage data corresponds to and is adjacent to the qth power equalization control data in the at least one power equalization control data, and the nth target AC voltage data is set before the qth power equalization control data; q is a positive integer; The main controller is further configured to determine the q-th target power of each converter subarray based on the q-th power equalization control data in the adjustment sequence, and synchronously send a q-th power adjustment command carrying the corresponding q-th target power to the second controller configured for each converter subarray based on the q-th target power, so that the second controller sends a q-th power output command to the drive controller connected in communication based on the received q-th power adjustment command, and controls the drive controller to control the corresponding converter to output the q-th target power.

12. The main controller as described in claim 11, characterized in that, In the adjustment sequence, the number of power equalization control data is the same as the number of target AC voltage data; and in the adjustment sequence, the target AC voltage data and the power equalization control data are arranged alternately. Alternatively, in the adjustment sequence, the number of power equalization control data is less than the number of target AC voltage data; and in the adjustment sequence, at least one target AC voltage data is set between two adjacent power equalization control data.

13. The main controller as described in claim 11 or 12, characterized in that, The main controller is further configured to acquire the power of the output port of each converter subarray, determine the average power of each converter subarray based on the power of the output port of each converter subarray and the number of converters in each converter subarray, and determine the determined average power of each converter subarray as the q-th target power of each converter subarray.

14. An electric power system, characterized in that, include: The system comprises multiple DC sources, multiple first transformers, multiple control switches, multiple converter subarrays, a first AC bus, and a black start controller; wherein, each of the multiple converter subarrays corresponds one-to-one with the multiple DC sources and the multiple first transformers; and one of the multiple converter subarrays corresponds to at least one of the multiple control switches. At least one of the plurality of converter subarrays includes at least one converter, the input port of each of the plurality of converter subarrays is connected to the DC source, and the output port of each of the plurality of converter subarrays is connected to the first AC bus through a first transformer and a control switch. The black start controller includes: a first controller and multiple second controllers, wherein the multiple second controllers are connected one-to-one with the multiple converter subarrays; The first controller is configured to sequentially execute the operation process of the first voltage adjustment stage to the Nth voltage adjustment stage when the control switch is in the closed state and the converter in each of the converter subarrays is in the powered-on state; and, in the nth voltage adjustment stage among the first to Nth voltage adjustment stages, synchronously send the nth target voltage adjustment command to each of the plurality of second controllers, controlling each second controller to drive the converter subarray connected to it to output the nth target AC voltage, so that the nth target AC voltage is converted into the nth target bus AC voltage input to the first AC bus via the first transformer; Wherein, n and N are integers greater than 1; 2≤n≤N, the nth target AC voltage is greater than the (n-1)th target AC voltage, the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

15. A black-start control method based on multiple converter subarrays, characterized in that, The black-start control method is applied to a black-start controller, which includes a first controller and multiple second controllers. The multiple second controllers are connected one-to-one with the multiple converter subarrays. At least one of the multiple converter subarrays includes at least one converter. The input port of each of the multiple converter subarrays is connected to a DC source, and the output port of each of the multiple converter subarrays is connected to a first AC bus through a first transformer and a control switch. The black start control method includes: After controlling the control switch to be in the closed state and controlling the converter in each converter subarray to be in the powered-on state, the first controller sequentially executes the working process of the first voltage adjustment stage to the Nth voltage adjustment stage; and, in the nth voltage adjustment stage among the first voltage adjustment stage to the Nth voltage adjustment stage, the first controller synchronously sends the nth target voltage adjustment command to each of the plurality of second controllers, controlling each second controller to drive the converter subarray connected to it to output the nth target AC voltage, so that the nth target AC voltage is converted into the nth target bus AC voltage input to the first AC bus via the first transformer; Wherein, n and N are integers greater than 1; 2≤n≤N, the nth target AC voltage is greater than the (n-1)th target AC voltage, the nth target bus AC voltage is greater than the (n-1)th target bus AC voltage, and the Nth target bus AC voltage is the rated AC voltage of the first AC bus.

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