Network construction type converter cooperative control method and system

Abstract

The invention relates to the technical field of converter control, and discloses a cooperative control method and system for a network construction type converter. The network construction type converter cooperative control method comprises the steps of reading cooperative control parameters of an alternating current power grid set in a current time period through a cooperative control center, wherein the cooperative control parameters comprise an active power reference value, a voltage reference value and a frequency reference value; judging whether the first converter group and the second converter group start cooperative control or not through a cooperative control center; and if the first converter group and the second converter group start cooperative control, cooperative control is carried out on the converters based on the control parameters through a cooperative control center, and the cooperative control comprises active power cooperative control and frequency cooperative control. According to the invention, cooperative work of distributed power supplies such as photovoltaic cells and wind power generation and the interface converter and the grid-side converter of the power grid is realized, the grid-connected stability is improved, and safe operation of the power grid is protected.

Description

Technical Field

[0001] The present invention relates to the field of converter control technology, and in particular to a method and system for coordinated control of a grid-type converter. Background Art

[0002] As a power system access module, the converter can realize various forms of AC and DC power flow interaction through conversion, and is the core component for building various types of high-efficiency power transmission and distribution and smart grids. Traditional converters operate independently, with relatively simple functions and capacities. Their operation mode is difficult to meet the unified standards of efficient and stable operation and flexible expansion of the power grid. The rapid development of power electronics technology has promoted the rapid development of multiple converters based on digital communication and collaborative control technology, and the multi-converter interconnection system can realize diversified power flow interaction between various converters through flexible topology conversion, providing more options for efficient and flexible power grid operation. According to the actual topological structure and control strategy, the grid-type converter system can realize multiple power levels and complex types of power grid conversion. It is a key equipment in key areas such as various complex large power grids, important user groups, and DC transmission systems. It can realize rapid power transmission, efficient regulation of power flow, voltage support and high-quality power supply in regional power grids.

[0003] In recent years, with the large-scale application and continuous development of grid-type converters, the parallel interconnection of multiple converters has become more and more common. However, when multiple converters are connected in parallel, they are affected by factors such as network delay and environment, resulting in asynchronous operation, which in turn causes losses to the converters and affects the performance of the entire system. Summary of the invention

[0004] The main purpose of the present invention is to provide a method and system for coordinated control of a grid-type converter, aiming to solve the technical problem that when multiple converters are connected in parallel, there is asynchronous operation, which in turn causes losses to the converter and affects the operating performance of the entire system.

[0005] A first aspect of the present invention provides a coordinated control method for a grid-type converter, wherein each converter is connected to an AC power grid and is divided into a first converter group and a second converter group, wherein a coordinated control center of the converter is provided in the first converter group, and the coordinated control method for the grid-type converter comprises: Reading the coordinated control parameters of the AC power grid set in the current period through the coordinated control center, wherein the coordinated control parameters include: an active power reference value, a voltage reference value, and a frequency reference value; Determining, by the collaborative control center, whether the first converter group and the second converter group have both started collaborative control; If the first converter group and the second converter group have both started cooperative control, the converters are cooperatively controlled based on the control parameters by the cooperative control center, and the cooperative control includes: active power cooperative control and frequency cooperative control.

[0006] Optionally, in a first implementation manner of the first aspect of the present invention, the determining, by the collaborative control center, whether the first converter group and the second converter group have both started collaborative control includes: Reading the current active power value of each converter in the first converter group and the second converter group respectively through the collaborative control center; Determine whether the current active power value of each converter is greater than the set active power start threshold value, and if both are greater than the set active power start threshold value, start the coordinated control; Determining whether the first converter group and the second converter group both start cooperative control; If the first converter group or the second converter group does not start the coordinated control, reading the grid-side active power value of the converter in the current period; If the grid-side active power value of the converter in the current period is close to the active power reference value, coordinated control is started on the first converter group or the second converter group.

[0007] Optionally, in a second implementation manner of the first aspect of the present invention, the collaborative control of the converter based on the control parameter by the collaborative control center includes: When active power cooperative control is performed on the converter, the first current value and the first voltage value output by each converter in the group are read by the cooperative control center; Calculate the product of the phasor of the first current value and the phasor of the first voltage value and use it as the first active power value output by the converter, and compare the first active power value output by each converter with the active power reference value; When the first active power value output by the converter is less than the active power reference value, the reference current value is reduced to reduce the active output; when the first active power value output by the converter is greater than the active power reference value, the reference current value is increased to increase the active output; when the first active power value output by the converter is equal to the active power reference value, the existing current value is used to keep the active output unchanged.

[0008] Optionally, in a third implementation manner of the first aspect of the present invention, the collaborative control of the converter based on the control parameter by the collaborative control center includes: When frequency cooperative control is performed on the converter, the second current value and the second voltage value output by each converter in the group are read by the cooperative control center; Calculate the product of the phasor of the second current value and the phasor of the second voltage value and use the product as the second active power value output by the converter, and convert the second active power value into a fundamental frequency equivalent value; The base frequency equivalent value is subtracted from the grid-side frequency value of the converter, the subtracted value is multiplied by the base frequency multiple to obtain the voltage phasor, the voltage phasor sum is divided by the current phasor to obtain the AC current value, the AC current value is divided by the base frequency to obtain the AC current base frequency value, the AC current base frequency value is compared with the base frequency, if the AC current base frequency value is greater than the base frequency, the reactive current value output by the converter is reduced, if the AC current base frequency value is less than the base frequency, the reactive current value output by the converter is increased until the grid-side frequency value reaches the frequency reference value.

[0009] Optionally, in a fourth implementation of the first aspect of the present invention, the grid-type converter cooperative control method further includes: Monitoring the operating status of each converter through the collaborative control center; If the grid-side active power value of the current converter is greater than the set startup active power threshold, the grid-side voltage value is less than the voltage startup threshold, or the grid-side frequency value is lower than the frequency startup threshold, the current converter operation state is marked as the startup state; If the current converter fails, the grid-side voltage value is greater than the preset voltage too high threshold, or the grid-side voltage is higher than the preset voltage too low threshold, the current converter operation state is marked as a fault state; If the current converter fault is eliminated or the grid-side voltage value drops below the voltage start threshold again, the current converter operation state is marked as a normal state.

[0010] Optionally, in a fifth implementation of the first aspect of the present invention, the grid-type converter cooperative control method further includes: Determining the operating status of each converter by the collaborative control center; The collaborative control center performs intra-group collaborative control according to the operating status of each converter, and performs inter-group collaborative control according to the operating status of each converter.

[0011] Optionally, in a sixth implementation manner of the first aspect of the present invention, the determining, by the collaborative control center, the operating status of each converter includes: The collaborative control center determines whether the current converter is a converter that triggers the start of collaborative control. If so, the output active power of each converter is read to start the collaborative control judgment, otherwise no processing is performed; The collaborative control center determines the operating state of the current converter, and if the current converter is in the startup state, marks it as the startup state, otherwise no processing is performed; Determine whether the current converter is in a fault state through the collaborative control center. If the current converter is in a fault state, mark it as a fault state and determine whether it is an internal fault. Otherwise, do not process it. If the current converter is in a group fault, determine whether the drop in the grid-side frequency value of the current converter exceeds the preset fault threshold. If not, mark it as a group fault, otherwise mark it as a fault state; If the current converter is not in a group fault, it is marked as a normal state. Otherwise, it continues to determine whether the current active power value of the current converter is greater than the active power start threshold. If not, no processing is performed. Otherwise, it is marked as a start state.

[0012] Optionally, in a seventh implementation manner of the first aspect of the present invention, the performing intra-group collaborative control according to the operating status of each converter by the collaborative control center includes: When the converter has an internal fault and performs internal coordinated control, if the current converter is marked as a startup state or a fault state, the current converter is controlled to output normally through the coordinated control center until it is marked as a normal state; If the current converter is marked as being in the start-up state, the reference current value is increased and does not exceed the set current limit current; If the current converter is marked as normal, the original control output is maintained until it is marked as fault or start-up.

[0013] Optionally, in an eighth implementation manner of the first aspect of the present invention, the performing inter-group collaborative control according to the operating status of each converter by the collaborative control center includes: When the converter has an intra-group fault and performs inter-group collaborative control, if the current converter is marked as a startup state, the current converter is controlled to output normally through the collaborative control center until it is marked as a fault or startup state; If the current converter is marked as a fault state, the reference current value is increased and does not exceed the set current state limit current; If the current converter is marked as normal, the original control output is maintained until it is marked as a fault state or a start-up state.

[0014] The second aspect of the present invention also provides a meshed converter collaborative control system, which includes multiple converters connected to an AC power grid and a collaborative control center of the converters, wherein each converter is divided into a first converter group and a second converter group, and the collaborative control center is arranged in the first converter group; the collaborative control center is used to execute the meshed converter collaborative control method described in any one of the above items.

[0015] In the technical solution provided by the present invention, the collaborative control center makes startup judgments for two groups of converters, and performs stable and coordinated control of the grid-side frequency, voltage, and active power through the coordinated input of the converters. At the same time, the collaborative control center is set on a group of converters, and performs collaborative control by reading the grid-side active power, voltage, and frequency in the current period, avoiding mutual inhibition or even self-excited oscillation between converters of different grid configurations due to asynchronous operation, making the converter operation more stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a first embodiment of a coordinated control method for a grid-type converter according to an embodiment of the present invention; Figure 2 It is a schematic diagram of a second embodiment of the coordinated control method of a grid-type converter in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" or "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0018] For ease of understanding, the specific process of the embodiment of the present invention is described below. Figure 1 , a first embodiment of the coordinated control method of a grid-type converter in an embodiment of the present invention includes: 101. Reading, through the collaborative control center, collaborative control parameters of the AC power grid set in the current period, the collaborative control parameters including: an active power reference value, a voltage reference value, and a frequency reference value; In this embodiment, before performing converter coordinated control, the converters connected to the AC power grid need to be divided into a first converter group and a second converter group, and a converter coordinated control center is provided in the first converter group.

[0019] In this embodiment, before grouping, it is necessary to perform a grid topology scan. Specifically, an impedance scanner is used to inject a high-frequency signal (1-10kHz), and the impedance characteristics of the grid nodes are analyzed through FFT. The PMU collects the bus voltage phase difference in real time, generates a dynamic topology map, and then compares and verifies the scan results with the SCADA system topology map. The error is required to be <2%. The SCADA (Supervisory Control And Data Acquisition) system, that is, the data acquisition and monitoring control system, can obtain the grid topology structure diagram, thereby identifying the grid connection point, feeder level and adjacent node relationship of each converter. Finally, grouping is performed based on the preset grouping rules: The first group (main control group): select the converter closest to the grid hub node (such as the converter connected to the main transformer) to ensure tight electrical coupling.

[0020] The second group (slave control group): converters distributed at the end of the power grid or in light-load areas.

[0021] The specific grouping method can be calculated by PowerFactory or PSCAD to verify the rationality of the grouping. In addition, the capacity relationship must also be considered during the grouping process, as follows: The total capacity of the master control group ≥ the capacity of the slave control group × 1.2; The capacity difference of a single converter is ≤ 10%.

[0022] Among them, the master control group: contains at least one converter with black start capability, equipped with redundant control units (master / backup dual-machine hot standby); the slave control group: supports "plug and play" mode, and automatically reports device ID and capacity information through the CAN bus.

[0023] Main control group equipment: Install GPS / Beidou dual-mode clock synchronization module (±1μs accuracy), deploy industrial-grade switches (support IEEE 1588 PTP protocol), and build a ring fiber optic network.

[0024] Slave control group equipment: Configure fast response contactor (action time ≤ 10ms) and support remote opening and closing control.

[0025] The collaborative control center is deployed in the main control group. The core processor uses FPGA to implement the communication protocol stack and data preprocessing. The DSP runs the control algorithm with a calculation cycle of ≤100μs. In terms of redundancy design, dual power supply modules (AC / DC + supercapacitor energy storage) and mirror storage units (RAID 1 configuration) are used, and the data update cycle is ≤1ms.

[0026] Communication configuration of collaborative control center: In the main control group: TSN (time-sensitive network) is used, with a cycle of 1ms and a jitter of <50μs.

[0027] Between master and slave groups: using IEC 61850-8-1 GOOSE protocol, transmission delay <5ms.

[0028] Scheduling system connection: OPC UA over TSN, supporting 1,000 data point updates per second.

[0029] In this embodiment, the collaborative control center communicates with the power grid management system or control center through a preset communication interface (such as Ethernet, serial communication, etc.) to obtain the collaborative control parameters of the AC power grid set in the current period. These parameters include but are not limited to active power reference value, voltage reference value and frequency reference value.

[0030] In this embodiment, after obtaining the collaborative control parameters, the collaborative control center first performs parameter verification to ensure the legality and accuracy of the parameters. The verification process may include checking the value range, data type, etc. of the parameters. After the verification is passed, the parameters are stored in the memory or database of the collaborative control center for subsequent use. In order to ensure the real-time and accuracy of the collaborative control parameters, the collaborative control center needs to update the parameters regularly or according to trigger conditions. Trigger conditions may include the arrival of time intervals, changes in power grid status, etc. The update process also includes parameter acquisition, verification, and storage.

[0031] 102. Determine, by the collaborative control center, whether the first converter group and the second converter group have both started collaborative control; In this embodiment, the collaborative control center communicates with the first converter group and the second converter group through a communication interface to obtain their status information. The status information may include operating status, fault status, control mode, etc.

[0032] The collaborative control center determines whether the first converter group and the second converter group have both started collaborative control based on the acquired status information. The judgment logic may include checking whether each converter group is in a preset control mode and whether a collaborative control start instruction has been received. If an abnormal converter group status is detected (such as not started, fault, etc.), the collaborative control center will take corresponding processing measures.

[0033] In one embodiment, the step 102 further includes: 1021. Reading, through the collaborative control center, the current active power value of each converter in the first converter group and the second converter group respectively; The collaborative control center needs to first obtain the current active power value of each converter in the first converter group and the second converter group, which is the basic data for determining whether to start collaborative control of the converter groups.

[0034] The collaborative control center needs to establish a stable communication connection with each converter, usually through a local area network (LAN), wide area network (WAN) or a dedicated communication bus (such as CAN bus, Modbus, etc.). The communication protocol should be selected according to the specific equipment and system requirements to ensure the reliability and real-time performance of data transmission.

[0035] The collaborative control center sends a command to read the current active power value to each converter through the communication connection. The command format should follow the communication protocol specification, including information such as command type, converter identification, and read parameters (active power). After receiving the read command, each converter sends the current active power value back to the collaborative control center through the communication connection. After receiving the data, the collaborative control center parses the current active power value of each converter according to the communication protocol specification.

[0036] The collaborative control center stores the parsed current active power value in a local database or memory for subsequent processing and judgment. The data storage format should consider the balance between data reading speed and storage space to ensure fast access and effective management of data.

[0037] 1022. Determine whether the current active power value of each converter is greater than the set active power start threshold value. If both are greater than the set active power start threshold value, start the coordinated control. After obtaining the current active power value of each converter, the collaborative control center needs to determine whether these values ​​are greater than the set active power start threshold to decide whether to start collaborative control. According to system requirements and equipment characteristics, a reasonable active power start threshold is set. The threshold setting should take into account factors such as equipment rated power, system stability, and power loss.

[0038] The collaborative control center compares the current active power value of each converter with the set active power start threshold. If the current active power value is greater than the threshold, the converter is considered to meet the conditions for starting collaborative control. The collaborative control center checks whether all converters in the first converter group and the second converter group meet the condition that the current active power value is greater than the threshold. If all converters meet the conditions, the next step of starting collaborative control is entered.

[0039] In this embodiment, the threshold setting should be adjusted according to the actual situation to ensure the accuracy and effectiveness of the collaborative control. In the comparison process, the real-time and accuracy of the data should be considered to avoid misjudgment caused by data delay or error.

[0040] 1023. Determine whether the first converter group and the second converter group both start coordinated control; After confirming that each converter meets the conditions for starting cooperative control, the cooperative control center needs to determine whether the first converter group and the second converter group have both started cooperative control. The cooperative control center can check the cooperative control status flag of each converter or converter group. The status flag is usually a Boolean value or an enumeration value, which is used to indicate whether the converter or converter group has started cooperative control.

[0041] The cooperative control center checks the cooperative control status flags of the first converter group and the second converter group respectively. If the status flags of the two groups both indicate that the cooperative control has been started, it is considered that the cooperative control has been started for both groups.

[0042] 1024. If the first converter group or the second converter group does not start the coordinated control, read the grid-side active power value of the converter in the current period; If the coordinated control is not started in any of the first converter group or the second converter group, the coordinated control center needs to read the grid-side active power value of the converter in the current period to further determine whether the coordinated control needs to be started.

[0043] The collaborative control center determines the current time period based on the system clock or timestamp. The time period division should be set according to the system requirements and operation strategy, such as by hour, minute or specific time period. The collaborative control center reads the grid-side active power value of each converter in the current time period through the communication connection. The grid-side active power value refers to the active power value exchanged between the converter and the grid, which is used to reflect the power output or absorption of the converter to the grid.

[0044] The collaborative control center stores the grid-side active power value read in the local database or memory for subsequent processing and judgment. The data storage format should consider the balance between data reading speed and storage space to ensure fast access and effective management of data.

[0045] 1025. If the grid-side active power value of the converter in the current period is close to the active power reference value, start coordinated control of the first converter group or the second converter group.

[0046] After reading the grid-side active power values ​​of the converters in the current period, the collaborative control center needs to determine whether these values ​​are close to the set active power reference values ​​to decide whether to start collaborative control for the first converter group or the second converter group that has not started collaborative control.

[0047] According to the system requirements and operation strategies, a reasonable active power reference value is set. The reference value setting should take into account factors such as system stability, power balance, and energy efficiency optimization. The collaborative control center compares the grid-side active power value of each converter in the current period with the set active power reference value. The comparison result can be expressed as an error value or deviation percentage to reflect the degree of closeness between the grid-side active power value and the reference value.

[0048] If the error value or deviation percentage between the grid-side active power value of all converters and the reference value in the current period is within the set tolerance range (i.e. close to the reference value), it is considered that coordinated control needs to be started. The tolerance range should be set according to system requirements and operation strategies to ensure the accuracy and effectiveness of coordinated control.

[0049] The collaborative control center sends a command to start collaborative control to the first converter group or the second converter group that has not started collaborative control. The command format should comply with the communication protocol specification, including information such as the command type, converter group identifier, and collaborative control parameters. After starting collaborative control, the collaborative control center updates the collaborative control status flags of the first converter group and the second converter group to reflect the current collaborative control status.

[0050] 103. If the first converter group and the second converter group have both started cooperative control, the converters are cooperatively controlled based on the control parameters by the cooperative control center, and the cooperative control includes: active power cooperative control and frequency cooperative control.

[0051] (1) Active power coordinated control: Specifically, the output power of the converter group is adjusted according to the active power reference value to maintain the active power balance of the power grid.

[0052] For example, by adjusting the output voltage amplitude and phase angle of the converter group, the active power distribution and regulation are achieved. The droop factor determines the response speed of the converter group to power changes.

[0053] For example, the characteristics of synchronous generators can be simulated to improve the stability and response speed of the power grid by adjusting the inertia, damping and other parameters of the converter group. Or advanced optimization algorithms (such as genetic algorithms, particle swarm algorithms, etc.) can be used to calculate the optimal active power distribution plan based on the real-time status and control objectives of the power grid.

[0054] In this embodiment, the output power, grid voltage, current and other parameters of the converter group are collected in real time. Then, the output power that needs to be adjusted by the converter group is calculated based on the collected data and the control strategy. Finally, the calculated control signal is sent to the converter group to adjust its output power.

[0055] (2) Frequency coordinated control: Specifically, the output frequency of the converter group is adjusted according to the frequency reference value to maintain the frequency stability of the power grid.

[0056] For example, by adjusting the relationship between the output frequency and active power of the converter group, frequency regulation and distribution are achieved. The droop factor determines the response speed of the converter group to frequency changes.

[0057] For example, by simulating the inertial characteristics of synchronous generators, the charging and discharging process of the energy storage elements (such as capacitors and inductors) of the converter group can be adjusted to provide additional inertial support and improve the frequency stability of the power grid. Alternatively, a fast-response controller (such as a proportional-integral-differential controller) can be used to quickly adjust the output frequency of the converter group according to the frequency deviation.

[0058] In this embodiment, the frequency parameters of the power grid are monitored in real time. Then, the output frequency that needs to be adjusted by the converter group is calculated based on the monitored frequency parameters and the control strategy. Finally, the calculated control signal is sent to the converter group to adjust its output frequency.

[0059] This embodiment comprehensively considers multiple control objectives such as active power balance, frequency stability, and voltage quality, and adopts a multi-objective optimization algorithm (such as weighted sum method, Pareto optimal solution, etc.) to solve the optimal collaborative control strategy. According to the real-time state of the power grid and the changes in control objectives, the parameters and algorithms of the collaborative control strategy are adaptively adjusted to improve the flexibility and robustness of the control. A distributed control architecture is adopted to assign collaborative control tasks to multiple controllers or converter groups for execution, thereby improving the response speed and reliability of the control.

[0060] In addition, this embodiment can also evaluate the effect of the collaborative control strategy by real-time monitoring of the state parameters of the power grid (such as active power, frequency, voltage, etc.). The evaluation indicators may include control error, response time, stability, etc. According to the evaluation results, the collaborative control strategy is adjusted and optimized. The adjustment process may include modifying control parameters, improving control algorithms, adding or deleting control targets, etc. At the same time, key information in the collaborative control process (such as control parameters, control strategies, control effects, etc.) is recorded, and a report is generated for subsequent analysis and improvement.

[0061] The present invention avoids mutual inhibition or even self-excited oscillation caused by asynchronous operation of coordination strategies between different grid-type converters, making the converter operation more stable and reliable, and is beneficial to the stability of the power quality and even the grid frequency of the entire coordinated control system.

[0062] In one embodiment, in step 103, active power coordinated control is performed in the following manner: 1031. When active power collaborative control is performed on the converter, a first current value and a first voltage value output by each converter in the group are read through the collaborative control center; Active power collaborative control is one of the core functions of the collaborative control center. It achieves the balance and stability of the overall power of the system by adjusting the active output of each converter. In the collaborative control center, it is first necessary to read the first current value and the first voltage value output by each group of converters. These values ​​are obtained from each converter in real time through the data acquisition module and transmitted to the collaborative control center through the communication module.

[0063] The data acquisition module of the collaborative control center uses sensors and measuring devices to obtain the current and voltage values ​​of each converter in real time. These sensors and measuring devices need to have high precision and high stability to ensure the accuracy of the data. The collected current and voltage values ​​are transmitted to the collaborative control center through the communication module. The communication module uses a high-speed and reliable communication protocol to ensure the real-time and accuracy of the data. At the same time, the communication module also supports multiple communication methods to meet the needs of different systems. The received current and voltage values ​​are stored in the collaborative control center for subsequent calculation and processing.

[0064] 1032. Calculate the product of the phasor of the first current value and the phasor of the first voltage value and use the product as the first active power value output by the converter, and compare the first active power value output by each converter with the active power reference value; After obtaining the current and voltage values ​​of each converter, it is necessary to calculate the phasor product of these values ​​to obtain the active power value output by each converter. Express the current and voltage values ​​in phasor form, including amplitude and phase. This can be achieved through a phasor measurement unit (PMU) or a phasor transformation algorithm. Perform a dot product operation on the current phasor and the voltage phasor to obtain the active power value. This process can be achieved through complex multiplication, that is, P=I⋅V∗, where I is the current phasor and V∗ is the conjugate of the voltage phasor. Convert the result of the phasor product to an active power value. This usually involves calculating the square of the amplitude and the cosine of the phase.

[0065] 1033. When the first active power value output by the converter is less than the active power reference value, the reference current value is reduced to reduce the active output; when the first active power value output by the converter is greater than the active power reference value, the reference current value is increased to increase the active output; when the first active power value output by the converter is equal to the active power reference value, the existing current value is used to keep the active output unchanged.

[0066] After obtaining the active power values ​​output by each converter, it is necessary to compare these values ​​with the preset active power reference values ​​to determine whether the active output of the converter needs to be adjusted. The active power reference values ​​are usually set according to system requirements and the output capacity of the distributed power source. These values ​​can be set through system configuration parameters or manual input.

[0067] The active power output of each converter is compared with the reference value. This can be achieved by a simple subtraction operation, that is, calculating P 实际 −P 参考 , according to the comparison results, it is determined whether the active output of each converter needs to be adjusted. If the actual power is less than the reference value, the active output needs to be increased; if the actual power is greater than the reference value, the active output needs to be reduced; if the actual power is equal to the reference value, the current output remains unchanged. According to the comparison results, the collaborative control center needs to adjust the reference current value of each converter to control its active output.

[0068] According to the comparison results, formulate corresponding adjustment strategies. If the actual power is less than the reference value, increase the reference current value; if the actual power is greater than the reference value, reduce the reference current value; if the actual power is equal to the reference value, keep the current reference current value unchanged. Send the adjusted reference current value to each converter. This can be achieved by controlling the output module to send the adjustment command to the converter in the form of a digital or analog signal. After receiving the adjustment command, each converter adjusts its output current according to the command. This usually involves current control algorithms and PWM modulation techniques.

[0069] In the process of active power collaborative control, it is necessary to monitor the output status of each converter in real time and make feedback adjustments according to the actual situation. The data acquisition module and communication module of the collaborative control center monitor the current, voltage, power and other parameters of each converter in real time. These parameters reflect the operating status and performance of the converter. According to the real-time monitoring results, the control strategy is adjusted. If the output status of a converter is found to be abnormal or deviates from the preset value, feedback adjustment is required. This can be achieved by modifying the control parameters or resetting the reference value. Through continuous monitoring and feedback adjustment, the control strategy is optimized and the control accuracy is improved. This can ensure that the system can operate stably under different working conditions and achieve efficient energy conversion.

[0070] In one embodiment, in step 103, frequency coordinated control is performed in the following manner: 1034. When frequency coordinated control is performed on the converter, the second current value and the second voltage value output by each converter in the group are read by the coordinated control center; The collaborative control center needs to establish a communication connection with each converter. For example, it can be achieved through a local area network (LAN), a wide area network (WAN) or a dedicated communication protocol. The collaborative control center sends a data request instruction to each converter, requesting the current current and voltage values. After receiving the instruction, each converter sends the current current (recorded as the second current value) and voltage (recorded as the second voltage value) data to the collaborative control center through a communication link. After receiving the data, the collaborative control center stores it in a local database or memory for subsequent calculation and analysis.

[0071] This embodiment needs to ensure that the communication protocol between the collaborative control center and the converter is compatible and can achieve accurate data transmission. At the same time, a unified data format is defined, including data type, data length, data unit, etc., to ensure data accuracy and consistency. In addition, it is necessary to ensure that the data provided by each converter is synchronized and collected at the same time point. This can be achieved by setting a unified sampling time interval or using a timestamp.

[0072] 1035. Calculate the product of the phasor of the second current value and the phasor of the second voltage value and use the product as the second active power value output by the converter, and convert the second active power value into a fundamental frequency equivalent value; The second current value and the second voltage value are converted from the time domain to the frequency domain to obtain their phasor representation. This is usually achieved through mathematical methods such as Fourier transform. The product of the second current phasor and the second voltage phasor is calculated to obtain the second active power value output by the converter. This value represents the active power delivered by the converter to the grid at the current moment. Since the current and voltage in the grid may contain multiple frequency components, in order to simplify calculation and analysis, the second active power value needs to be converted into a base frequency equivalent value. This is usually achieved through a filter or mathematical transformation to extract the active power component corresponding to the base frequency.

[0073] 1036. Subtract the base frequency equivalent value from the grid-side frequency value of the converter, multiply the subtracted value by the base frequency multiple to obtain the voltage phasor, divide the voltage phasor sum by the current phasor to obtain the AC current value, divide the AC current value by the base frequency to obtain the AC current base frequency value, compare the AC current base frequency value with the base frequency, if the AC current base frequency value is greater than the base frequency, reduce the reactive current value output by the converter, if the AC current base frequency value is less than the base frequency, increase the reactive current value output by the converter until the grid-side frequency value reaches the frequency reference value.

[0074] Calculate the difference between the base frequency equivalent value and the grid-side frequency value of the converter. This difference reflects the deviation between the current active power and the desired frequency. Then, multiply the difference by a base frequency multiple (usually a constant) to obtain the voltage phasor that needs to be adjusted. This voltage phasor represents the magnitude and direction of the voltage that needs to be changed in order to adjust the frequency. Then divide the voltage phasor by the current phasor to obtain the AC current value, which represents the magnitude and direction of the current that needs to be changed in order to adjust the frequency. Finally, divide the AC current value by the base frequency to obtain the AC current base frequency value, which represents the current component corresponding to the base frequency.

[0075] See also Figure 2 , Figure 2 This is a second embodiment of the coordinated control method for a grid-type converter in an embodiment of the present invention. In this embodiment, in the process of coordinated control of the converter by the coordinated control center based on the control parameter, the coordinated control method for a grid-type converter further includes: 201. Monitoring the operating status of each converter through the collaborative control center; Corresponding sensors are configured inside each converter to collect key parameters such as grid-side active power, grid-side voltage, and grid-side frequency in real time. These sensors should have high precision and high reliability to ensure that the collected data is accurate and reliable.

[0076] The converter transmits the collected data to the collaborative control center in real time through built-in communication devices (such as Ethernet interface, RS485 interface, etc.). The collaborative control center should be configured with corresponding communication interfaces and protocols to ensure that the data from each converter can be correctly received and processed.

[0077] The collaborative control center receives data from each converter through the communication interface and stores it in the corresponding data buffer. The collaborative control center pre-processes the received data, including data verification, data filtering and data conversion. Data verification is used to check the integrity and correctness of the data; data filtering is used to remove noise and interference; data conversion is used to convert the original data into a format that can be used for subsequent processing and analysis.

[0078] The collaborative control center updates the operating status information of each converter in real time, including the current active power value, voltage value, and frequency value, etc. The collaborative control center displays the operating status information of each converter in a graphical or textual manner on the monitoring interface, making it convenient for operation and maintenance personnel to view and understand the operating status of each converter in real time.

[0079] 202. If the grid-side active power value of the current converter is greater than the set startup active power threshold, the grid-side voltage value is less than the voltage startup threshold, or the grid-side frequency value is lower than the frequency startup threshold, the current operation state of the converter is marked as the startup state; According to the system requirements and the rated power of the converter, set an appropriate startup active power threshold. When the grid-side active power value of the converter exceeds this threshold, the converter is considered to be in the startup state. According to the system voltage level and the rated voltage of the converter, set an appropriate voltage startup threshold. When the grid-side voltage value of the converter is lower than this threshold, the converter is considered to have one of the startup conditions. According to the system frequency range and the rated frequency of the converter, set an appropriate frequency startup threshold. When the grid-side frequency value of the converter is lower than this threshold, the converter is considered to have one of the startup conditions.

[0080] The collaborative control center compares the grid-side active power value, grid-side voltage value and grid-side frequency value of each converter with the corresponding threshold value in real time. When one of the following conditions is met, the current converter operation status is marked as the startup status: (1) The grid-side active power value is greater than the set startup active power threshold; (2) The grid-side voltage value is less than the voltage start threshold; (3) The grid-side frequency value is lower than the frequency start threshold.

[0081] The collaborative control center records the information of the converters that are determined to be in the startup state in the log, including the converter number, startup time, startup conditions, etc. The collaborative control center notifies the operation and maintenance personnel through SMS, email or system messages that there are converters in the startup state, so that the operation and maintenance personnel can take timely measures for subsequent operations.

[0082] 203. If the current converter fails, the grid-side voltage value is greater than a preset voltage too high threshold, or the grid-side voltage is higher than a preset voltage too low threshold, the current converter operation state is marked as a fault state; Built-in fault detection: The converter is equipped with a fault detection module to detect in real time whether the converter has any faults. The fault detection module can detect circuit faults, overheating faults, overcurrent faults, etc. inside the converter.

[0083] Voltage anomaly detection: The collaborative control center compares the grid-side voltage value of each converter with the preset overvoltage threshold and undervoltage threshold in real time. When the grid-side voltage value exceeds the overvoltage threshold or is lower than the undervoltage threshold, the converter is considered to be in an abnormal voltage state.

[0084] Fault determination: When the internal fault detection module of the converter detects a fault, or when the grid-side voltage value of the converter exceeds the voltage-too-high threshold or is lower than the voltage-too-low threshold, the current operating state of the converter is marked as a fault state.

[0085] The collaborative control center records the information of the converter that is judged to be in a fault state in the log, including the converter number, fault time, fault type (circuit fault, overheating fault, overcurrent fault, overvoltage fault, undervoltage fault, etc.), fault parameters, etc. The collaborative control center notifies the operation and maintenance personnel through sound and light alarms, text messages, emails or system messages that a converter is currently in a fault state, and prompts the fault type and possible fault cause.

[0086] When possible, the collaborative control center can automatically or manually isolate the faulty converter from the system by the operation and maintenance personnel to prevent the fault from spreading and affecting the normal operation of other equipment.

[0087] 204. If the current converter fault is eliminated or the grid-side voltage value drops below the voltage start threshold again, the current converter operation state is marked as a normal state.

[0088] Fault recovery detection: When a converter fails, the collaborative control center or operation and maintenance personnel can take appropriate measures to repair the fault. After the fault is repaired, the fault detection module inside the converter will re-detect the converter status and confirm whether the fault has been eliminated.

[0089] Voltage recovery detection: When the grid-side voltage value of the converter exceeds the voltage over-threshold or is lower than the voltage under-threshold, causing the converter to enter a fault state, the collaborative control center will monitor the changes in the grid-side voltage value in real time. When the grid-side voltage value returns to the normal range (i.e., lower than the voltage start threshold), the voltage abnormality is considered to have been eliminated.

[0090] Normal state judgment: When one of the following conditions is met, the current operating state of the converter is marked as normal: (1) The converter internal fault detection module confirms that the fault has been eliminated; (2) The grid-side voltage value of the converter returns to the normal range (i.e., lower than the voltage start threshold).

[0091] The collaborative control center records the information of the converters that are judged to be in normal state in the log, including the converter number, recovery time, recovery conditions, etc. The collaborative control center notifies the operation and maintenance personnel that the current converter has returned to normal state through SMS, email or system message. After confirming that the converter has returned to normal state, the collaborative control center can automatically or manually connect the converter to the system through the operation and maintenance personnel to restore the normal operation of the system.

[0092] In an optional embodiment, in the process of monitoring the operating status of each converter by the collaborative control center, the grid-type converter collaborative control method further includes: 205. Determine the operating status of each converter through the collaborative control center; Corresponding sensors are configured inside each grid-type converter to collect key operating parameters in real time, such as DC side voltage, AC side current, grid side voltage, grid side frequency, active power, reactive power, etc. These sensors should have high precision and high reliability to ensure that the collected data is accurate and reliable.

[0093] The converter transmits the collected data to the collaborative control center in real time through built-in communication devices (such as Ethernet interface, wireless communication module, etc.). The collaborative control center should be configured with corresponding communication interfaces and protocols to ensure that the data from each converter can be correctly received and processed.

[0094] The collaborative control center pre-processes the received data, including data verification, data filtering, data conversion, etc. Data verification is used to check the integrity and correctness of the data; data filtering is used to remove noise and interference; data conversion is used to convert the original data into a format that can be used for subsequent processing and analysis.

[0095] According to the system requirements and the rated parameters of the converter, a series of thresholds are set to judge the operating status of the converter. These thresholds include the upper and lower limits of the DC side voltage, the upper and lower limits of the AC side current, the upper and lower limits of the grid side voltage, the upper and lower limits of the grid side frequency, the upper and lower limits of the active power, and the upper and lower limits of the reactive power.

[0096] The collaborative control center determines the operating status of each converter based on the collected data and the preset threshold. The operating status can be divided into normal status, warning status and fault status. The normal status means that the converter is operating within the normal range; the warning status means that the converter operating parameters are close to or exceed the threshold, but no fault has occurred; the fault status means that the converter has failed or the operating parameters have seriously exceeded the threshold.

[0097] The collaborative control center records the judgment results in the status log, including the converter number, operating status, judgment time, related parameters, etc. The status log can be used for subsequent data analysis and troubleshooting. The collaborative control center displays the operating status of each converter in a graphical or textual manner on the monitoring interface, which is convenient for operation and maintenance personnel to view and understand the operating status of each converter in real time. The monitoring interface can display the real-time parameters, historical data, status trends and other information of the converter. When the converter enters the warning state or fault state, the collaborative control center notifies the operation and maintenance personnel through SMS, email, system message, etc. The notification content includes the converter number, operating status, related parameters, recommended measures, etc. The operation and maintenance personnel can take timely measures to troubleshoot and repair the fault according to the notification content.

[0098] In an optional embodiment, the above step 205 further includes: 2051. Determine, through the collaborative control center, whether the current converter is a converter that triggers the start of collaborative control. If so, read the output active power of each converter to start the collaborative control judgment. Otherwise, do not process. The collaborative control center first receives instructions or signals from the system, which may come from the superior dispatching system, the local operation interface or other triggering mechanisms. These instructions usually contain a specific converter identification (ID) or group identification to indicate which converters need to start collaborative control.

[0099] The collaborative control center matches and verifies the received converter ID with the converter ID registered in the system. This step ensures that the instruction is for the converter that actually exists in the system to avoid misoperation. If the match is successful and the converter is designated as the converter that triggers the start of collaborative control, the collaborative control center proceeds to the next step; otherwise, no collaborative control processing is performed on the converter.

[0100] The collaborative control center and the converter use standardized communication protocols (such as Modbus, CANopen, etc.) for data transmission to ensure the accuracy and real-time nature of the information. In the process of receiving and sending data, checksums (such as CRC checksums) are used to detect errors in data transmission. The collaborative control center records the results of each instruction reception, matching verification, and startup judgment for subsequent analysis and troubleshooting.

[0101] The collaborative control center sends a data request instruction to the converter designated to start collaborative control, requiring it to report the current output active power value. Each converter responds to the data request of the collaborative control center and sends its own output active power value back to the collaborative control center through the communication protocol. The collaborative control center receives and parses this data to extract the active power value of each converter. The collaborative control center judges the active power value of each converter based on the preset collaborative control start conditions (such as active power deviation range, total system power demand, etc.). If the start conditions are met, the collaborative control process is entered; otherwise, no collaborative control processing is performed.

[0102] To ensure data synchronization, the collaborative control center sets a unified timestamp when sending data request instructions, requiring each converter to include the timestamp in the reply so that the collaborative control center can perform time synchronization processing. The received active power data is filtered to remove noise and outliers to improve the accuracy and reliability of the data. The threshold for starting collaborative control should be set according to the actual system conditions, including the active power deviation range, the total power demand of the system, etc. These thresholds can be adjusted through the configuration interface of the collaborative control center.

[0103] 2052. Determine the operating state of the current converter through the collaborative control center. If the current converter is in the startup state, mark it as the startup state. Otherwise, do not process it. The collaborative control center sends status query instructions to each converter regularly or on demand, requiring it to report its current operating status. Each converter responds to the status query instruction of the collaborative control center and sends its own operating status back to the collaborative control center through the communication protocol. The collaborative control center receives and parses this data to extract the operating status information of each converter. Based on the parsed operating status information, the collaborative control center determines whether the current converter is in the startup state. If it is in the startup state, it is marked as the startup state and the system status table is updated; otherwise, no processing is performed.

[0104] Each converter should use a unified status code to indicate its operating status, such as "running", "standby", "fault", etc. The collaborative control center makes judgments based on these status codes.

[0105] Status update: After determining the status of the converter, the collaborative control center should update the system status table in a timely manner so that other modules or systems can obtain the latest converter status information. If the collaborative control center does not receive a status reply from a converter within the specified time, it is considered an abnormal state and corresponding abnormal processing is performed (such as sending alarm information, recording logs, etc.).

[0106] 2053. Determine whether the current converter is in a fault state through the collaborative control center. If the current converter is in a fault state, mark it as a fault state and determine whether it is an internal fault. Otherwise, do not process it. The collaborative control center monitors the operating status information and log records of each converter to detect whether there is a fault state. Fault states may include hardware faults, software faults, communication faults, etc. If a fault state is detected, the collaborative control center will further confirm the type and severity of the fault. This usually involves a detailed analysis of the fault log, interaction with other modules, and possible on-site inspections. Based on the results of the fault confirmation, the collaborative control center marks the current converter as a fault state and records the fault information (such as fault time, fault type, fault level, etc.) in the fault log.

[0107] Faults should be classified according to their nature and impact, such as emergency faults, serious faults, general faults, etc. Different types of faults should have different processing procedures and priorities. After confirming the fault, the collaborative control center should take measures to isolate the faulty converter as soon as possible to prevent the fault from spreading or affecting the normal operation of other converters. The collaborative control center should send fault notifications to relevant personnel or systems in a timely manner so that they can respond quickly and take necessary repair measures.

[0108] 2054. If the current converter is in a group fault, determine whether the drop in the grid-side frequency value of the current converter exceeds a preset fault threshold, if not, mark it as a group fault, otherwise, mark it as a fault state; The collaborative control center continuously monitors the grid-side frequency value of each converter to understand the operating status of the power grid in real time. If a converter is marked as a group fault state (that is, the converter logically belongs to the same group as other converters, and other converters in the group also have faults), the collaborative control center will compare the current grid-side frequency value of the converter with the preset fault threshold. If the current grid-side frequency value drops by more than the preset fault threshold, it is considered that the fault of the converter has a significant impact on the stability of the power grid and should be marked as a serious fault within the group; otherwise, it is still marked as a group fault.

[0109] The preset fault thresholds should be set according to the actual situation and stability requirements of the power grid. These thresholds can be adjusted through the configuration interface of the collaborative control center. In addition to directly comparing the current frequency value with the threshold, the collaborative control center can also analyze the frequency change trend (such as change rate, fluctuation range, etc.) to more comprehensively evaluate the impact of the fault on the power grid. For serious faults within the group, the collaborative control center should take measures as soon as possible to isolate the faulty converter and try to restore the stability of the power grid. At the same time, relevant personnel or systems should be notified to troubleshoot and repair the fault.

[0110] 2055. If the current converter is not in a group fault, it is marked as a normal state. Otherwise, it continues to determine whether the current active power value of the current converter is greater than the active power start threshold. If not, no processing is performed. Otherwise, it is marked as a start state.

[0111] For converters with non-intra-group faults (i.e., the converter does not form a fault group with other converters), the collaborative control center will determine whether its current active power value is greater than the active power startup threshold. The active power startup threshold is a power value set according to system requirements and converter capabilities. If the current active power value is greater than the active power startup threshold, it is considered that the converter is in a faulty state but is still capable of participating in the power regulation and distribution of the system. At this time, the collaborative control center marks it as a startup state (but with a fault mark) and attempts to adjust its output power through a collaborative control strategy to maintain system stability. If the current active power value is not greater than the active power startup threshold, it is considered that the converter can no longer effectively participate in the system power regulation and should continue to be marked as a faulty state and perform corresponding fault processing.

[0112] For converters marked as faulty, the collaborative control center will take appropriate measures according to the fault type and severity, such as issuing alarm information, attempting to restart the converter, isolating the faulty converter, etc. At the same time, the collaborative control center will record the process and results of fault handling in the fault log for subsequent analysis and improvement. The active power startup threshold should be set according to the actual needs of the system and the capabilities of the converter. These thresholds can be adjusted through the configuration interface of the collaborative control center.

[0113] For converters marked as started but with fault marks, the collaborative control center should adopt appropriate collaborative control strategies to adjust their output power. These strategies may include power allocation algorithms, current limiting control algorithms, etc. After taking fault handling measures, the collaborative control center should continue to monitor the state changes of the faulty converter and verify whether the fault has been successfully eliminated. If the fault is still not eliminated, the corresponding handling measures should continue to be taken; if the fault has been eliminated, the system status table should be updated and the relevant personnel or system should be notified.

[0114] 206. Perform intra-group collaborative control according to the operating status of each converter and perform inter-group collaborative control according to the operating status of each converter through the collaborative control center.

[0115] (1) Intra-group collaborative control According to system requirements and factors such as the geographical location and functional characteristics of the converters, multiple converters are divided into different control groups. The converters in each control group have similar operating characteristics and control requirements. Control targets are set for each control group, including active power distribution, reactive power compensation, voltage regulation, frequency regulation, etc. The control targets should be adjusted and optimized according to system requirements and grid requirements.

[0116] According to the control target and the operating status of the converter, the intra-group collaborative control strategy is formulated. The control strategy may include droop control, virtual synchronous machine control, power distribution control, etc. Droop control realizes automatic power distribution by adjusting the output impedance and droop coefficient of the converter; virtual synchronous machine control realizes voltage and frequency stability by simulating the operating characteristics of the synchronous generator; power distribution control distributes the output power of each converter through the optimization algorithm.

[0117] The collaborative control center sends control instructions to the converters in each control group according to the formulated control strategy. The converter adjusts its output parameters according to the received control instructions to achieve the collaborative control objectives within the group. At the same time, the collaborative control center monitors the operating status and control effect of each converter in real time and makes adjustments and optimizations as needed.

[0118] In an optional embodiment, the step 206 further includes: performing intra-group collaborative control by the collaborative control center according to the operating status of each converter. 2061. When the converter has an intra-group fault and performs intra-group collaborative control, if the current converter is marked as a startup state or a fault state, the collaborative control center controls the current converter to output normally until it is marked as a normal state; The collaborative control center first identifies which converters are in a group fault state through real-time monitoring and data analysis. This usually involves a comprehensive evaluation of the converter operation data, including abnormal changes in key parameters such as voltage, current, and power factor. Once an intra-group fault is confirmed, the collaborative control center will immediately start the intra-group collaborative control program to optimize the energy distribution and regulation within the faulty group to ensure the overall stable operation of the system.

[0119] The collaborative control center checks the current status mark of each converter in the group. For converters marked as startup or faulty, the collaborative control center will adopt specific control strategies. For converters in startup, although they may have been affected by the fault, the collaborative control center will try to maintain their normal output by adjusting control parameters (such as voltage and current reference values). This is to ensure that as much energy as possible can be effectively used during the fault while reducing system instability.

[0120] For converters in faulty states, the collaborative control center will first assess the type and severity of the fault. If the fault does not affect the basic output function of the converter, the collaborative control center will try to restore its normal operation through software repair or adjustment of the control strategy. If the fault is serious and cannot be repaired immediately, the collaborative control center will put the converter in standby mode, awaiting further repair or replacement.

[0121] According to the formulated control strategy, the collaborative control center sends control instructions to each converter in the group and adjusts its output parameters to meet the requirements of the collaborative control in the group. During the execution of the control instructions, the collaborative control center will continuously monitor the operating status and output parameters of each converter to ensure that the control effect meets the expectations. Once the converter returns to normal (that is, the fault is repaired or the system stability is restored), the collaborative control center will update its status mark and adjust the control strategy accordingly.

[0122] 2062. If the current converter is marked as being in the startup state, the reference current value is increased and does not exceed the set current limit current; The collaborative control center first confirms that the converter is in the startup state and evaluates its current current demand and output capacity. The evaluation process may involve analysis of the converter's historical data, prediction of the grid load, and consideration of the status of other converters. Based on the evaluation results, the collaborative control center calculates a new reference current value that is designed to increase the converter's output capacity while ensuring that it does not exceed its set current state limit current. The purpose of setting the current state limit current is to protect the converter from overload damage while ensuring the overall stability of the system.

[0123] The collaborative control center sends the new reference current value as a control instruction to the converter, requiring it to adjust the output current to meet the new reference value. During the execution of the control instruction, the collaborative control center will continuously monitor the operating status and output parameters of the converter to ensure that the control effect meets expectations and does not cause new faults.

[0124] The current limiting strategy adopted by the collaborative control center should be dynamically adjusted based on the actual output capacity of the converter and the load demand of the power grid. This can be achieved by real-time monitoring and analysis of system data. In order to improve the accuracy and response speed of control, the collaborative control center may adopt advanced control algorithms such as PID control, fuzzy control or neural network control. When adjusting the reference current value, the collaborative control center should take into account the possible failure risks and take corresponding preventive measures, such as setting overcurrent protection, overheating protection, etc.

[0125] 2063. If the current converter is marked as normal, the original control output is maintained until it is marked as fault or startup state.

[0126] The collaborative control center first confirms that the converter is in a normal state, that is, its operating state is stable, the output parameters meet the system requirements, and there are no faults or abnormalities. Once the converter is confirmed to be in a normal state, the collaborative control center will maintain its original control output unchanged to ensure the stability and continuity of the system.

[0127] Although the converter is in normal condition, the collaborative control center still needs to continuously monitor its operating status and output parameters to prevent possible faults or abnormalities. If the collaborative control center detects any signs that may cause the converter state to change (such as voltage fluctuations, current anomalies, etc.), it will immediately activate the early warning mechanism and take corresponding preventive measures. If the state of the converter changes (such as from normal state to fault state or startup state), the collaborative control center will update its status mark in time and adjust the control strategy according to the new state. The adjustment of the control strategy may involve recalculation and adjustment of parameters such as reference current value and voltage reference value to ensure that the system can still maintain stable operation in the new state.

[0128] The collaborative control center uses high-precision sensors and advanced signal processing technologies to monitor the operating status and output parameters of the converter in real time. These technologies can provide accurate and reliable data support to help the collaborative control center make correct decisions. The collaborative control center uses early warning algorithms based on data analysis and machine learning to predict possible faults or anomalies. These algorithms can identify potential fault risks based on the changing trends of historical data and real-time data, and take corresponding preventive measures in advance. The control strategy of the collaborative control center should be highly flexible and scalable to meet the needs of different system environments and operating conditions. This can be achieved by adopting a modular design approach and configurable control parameters.

[0129] (2) Inter-group collaborative control According to the needs of the entire distributed energy system and the requirements of the power grid, set system-level control objectives. These objectives may include total active power output, total reactive power compensation, system voltage stability, system frequency stability, etc. According to the system-level control objectives and the operating status of each control group, formulate inter-group collaborative control strategies. Inter-group collaborative control strategies may include power balance control, voltage coordination control, frequency coordination control, etc. Power balance control achieves system total power balance by adjusting the output power of each control group; voltage coordination control achieves system voltage stability by adjusting the voltage output of each control group; frequency coordination control achieves system frequency stability by adjusting the frequency response of each control group.

[0130] The collaborative control center generates corresponding control instructions based on the formulated inter-group collaborative control strategy and sends them to each control group. Control instructions may include power adjustment instructions, voltage adjustment instructions, frequency adjustment instructions, etc. Each control group adjusts the output parameters of its internal converter according to the received control instructions to achieve the inter-group collaborative control goals. The collaborative control center monitors the operating status and control effect of each control group in real time and makes feedback adjustments as needed. If the operating status of a control group deviates from the preset range or the control effect is not ideal, the collaborative control center can adjust its control strategy in time or send coordination instructions to other control groups to achieve more stable system operation.

[0131] In an optional embodiment, the step 206 further includes: performing inter-group collaborative control according to the operating status of each converter by the collaborative control center: 2064. When the converter has an intra-group fault and performs inter-group collaborative control, if the current converter is marked as a startup state, the current converter is controlled to output normally through the collaborative control center until it is marked as a fault or startup state; Inter-group collaborative control refers to the unified management and optimization control of multiple converter groups in distributed energy systems through a collaborative control center to achieve efficient energy distribution, stable system operation and rapid response to faults. This control method takes into account the mutual influence and constraints between different converter groups, and formulates the optimal control strategy through comprehensive analysis and decision-making.

[0132] The operating status data of each converter is collected in real time through sensors and monitoring equipment, and preprocessed and cleaned to ensure the accuracy and reliability of the data. The collected data is deeply analyzed to identify the current status of each converter (such as startup status, fault status, normal status, etc.), and the corresponding control strategy is triggered according to the status change. According to the status monitoring results and the goals of inter-group collaborative control, a specific control strategy is formulated, and the control instructions are sent to each converter group through the communication protocol. The execution effect of the control strategy is evaluated in real time, and feedback data is collected to continuously optimize and improve the control strategy.

[0133] The collaborative control center first identifies which converters are in a group fault state by real-time monitoring and analyzing the operating status data of each converter. This usually involves a comprehensive analysis of abnormal changes in key parameters such as voltage, current, and power factor. Once an intra-group fault is confirmed, the collaborative control center will immediately start the inter-group collaborative control program to optimize the energy distribution and regulation between the faulty group and its adjacent groups.

[0134] The collaborative control center will check the current status mark of the faulty converter in the group. For the converter marked as started, although it may have been affected by the fault in the group, the collaborative control center will try to maintain its normal output by adjusting the control parameters (such as voltage reference value, current reference value, etc.). The purpose of this step is to make the best use of the available energy in the faulty group and reduce the impact of the fault on the overall system performance while ensuring the stability of the system.

[0135] The collaborative control center converts the formulated control strategy into specific control instructions and sends them to the current converter through the communication protocol. During the execution of the control instructions, the collaborative control center will continuously monitor the operating status and output parameters of the current converter to ensure that the control effect meets expectations. If the status of the current converter changes (such as from the startup state to the fault state), the collaborative control center will immediately update its status mark and adjust the control strategy according to the new state.

[0136] The collaborative control center uses advanced fault detection algorithms, such as anomaly detection based on machine learning and fault diagnosis based on physical models, to improve the accuracy and timeliness of fault identification. While maintaining the normal output of the current converter, the collaborative control center will dynamically adjust the control parameters based on the real-time operating data and historical data of the system to ensure the stability and efficiency of the system. The communication between the collaborative control center and the converter adopts standardized communication protocols (such as Modbus, CANopen, etc.) and is equipped with corresponding data encryption and verification mechanisms to ensure the security and integrity of the data.

[0137] 2065. If the current converter is marked as a fault state, the reference current value is increased and does not exceed the set current state limit current; The collaborative control center first confirms that the current converter is in a fault state and evaluates the impact of its fault type and severity on the overall performance of the system. Based on the evaluation results, the collaborative control center analyzes the current value required by the current converter in the fault state to determine whether it is necessary to increase the reference current value to improve its output capacity. The collaborative control center calculates a new reference current value based on the system's real-time operating data, historical data, and the current converter's fault state. This value is designed to increase the output capacity of the current converter while ensuring that it does not exceed its set current state limit current to avoid overload damage. The collaborative control center sends the new reference current value as a control instruction to the current converter, requiring it to adjust the output current to meet the new reference value. During the execution of the control instruction, the collaborative control center will continuously monitor the operating status and output parameters of the current converter to ensure that the control effect meets expectations and does not cause new faults.

[0138] When increasing the reference current value, the collaborative control center will comprehensively consider the actual output capacity of the current converter, the load demand of the system, and the impact of the fault on the system to ensure that the adjusted current value can meet the system requirements without causing damage to the converter. In order to improve the accuracy and response speed of control, the collaborative control center may adopt advanced control algorithms, such as PID control, fuzzy control, or neural network control. These algorithms can be dynamically adjusted and optimized based on the real-time operating data and historical data of the system. In the process of increasing the reference current value, the collaborative control center will monitor the operating status and output parameters of the current converter in real time. Once abnormal changes or potential fault risks are found, corresponding preventive measures will be taken immediately, such as reducing the output current and starting the protection mechanism.

[0139] 2066. If the current converter is marked as normal, the original control output is maintained until it is marked as a fault state or a start-up state.

[0140] The collaborative control center first confirms that the current converter is in a normal state, that is, its operating state is stable, the output parameters meet the system requirements, and there are no faults or abnormalities. Once it is confirmed that the current converter is in a normal state, the collaborative control center will maintain its original control output unchanged to ensure the stability and continuity of the system. Although the current converter is in a normal state, the collaborative control center still needs to continuously monitor its operating state and output parameters to prevent possible faults or abnormalities.

[0141] The collaborative control center will use advanced early warning algorithms and data analysis technologies to conduct real-time evaluation and analysis of the current operating status of the converter. Once abnormal changes or potential failure risks are found, the early warning mechanism will be immediately activated and corresponding preventive measures will be taken. If the current status of the converter changes (such as from normal state to fault state or startup state), the collaborative control center will update its status mark in time and adjust the control strategy according to the new state. The adjustment of the control strategy may involve recalculation and adjustment of parameters such as reference current value and voltage reference value to ensure that the system can still maintain stable operation in the new state.

[0142] The collaborative control center uses high-precision sensors and advanced signal processing technologies to monitor the current operating status and output parameters of the converter in real time. These technologies can provide accurate and reliable data support to help the collaborative control center make correct decisions. The collaborative control center uses early warning algorithms based on data analysis and machine learning to predict possible faults or abnormalities. These algorithms can identify potential fault risks based on the changing trends of historical data and real-time data, and take corresponding preventive measures in advance. The control strategy of the collaborative control center should be highly flexible and scalable to meet the needs of different system environments and operating conditions. This can be achieved by adopting a modular design approach and configurable control parameters. At the same time, the collaborative control center should also have the ability to self-learn and optimize, and be able to dynamically adjust and optimize the control strategy based on the real-time operating data and historical data of the system.

[0143] The present invention also provides a meshed-type converter collaborative control system, which includes a plurality of converters connected to an AC power grid and a collaborative control center of the converters, wherein each converter is divided into a first converter group and a second converter group, and the collaborative control center is arranged in the first converter group; the collaborative control center is used to execute the meshed-type converter collaborative control method described in any one of the above embodiments.

[0144] In distributed energy systems, grid-type converters are key devices that connect distributed power sources to the power grid. Their operating status and control strategy directly affect the stability, efficiency and reliability of the system. In order to achieve more efficient and stable system operation, collaborative control between grid-type converters is particularly important. Traditional independent control methods can no longer meet the high requirements of modern power grids for power quality and stability. Therefore, it is necessary to introduce a collaborative control strategy to optimize the overall performance of the system by centrally managing multiple converters. As the core of this strategy, the collaborative control center is responsible for receiving system status information and collaboratively controlling the converters according to preset control parameters to achieve stable operation of the system and efficient energy conversion.

[0145] In distributed energy systems, converters are key devices responsible for converting different forms of energy into electrical energy and injecting it into the power grid. In order to ensure the stable operation of the system and efficient energy management, the Centralized Coordination Control Center plays a vital role. By monitoring and adjusting the operating status of each converter, the Centralized Coordination Control Center can achieve optimal energy distribution and rapid response to system failures. The following is a detailed description of how to use the Coordination Control Center to determine the operating status of each converter, covering the entire process from starting the coordinated control judgment to handling the fault status. As the central processor, the Coordination Control Center is responsible for collecting the operating status data of each converter and performing status judgment and management according to the preset thresholds and logic. As the monitored object, the converter collects key parameters such as grid-side active power, grid-side voltage, and grid-side frequency in real time through built-in sensors, and sends these data to the Coordination Control Center through communication equipment.

[0146] The grid-type converter cooperative control system mainly consists of a cooperative control center, a first converter group, a second converter group, and other possible grid components (such as generators, loads, etc.). As the core, the cooperative control center is responsible for reading control parameters, judging the status of the converter group, and executing the cooperative control strategy.

[0147] Collaborative control center: responsible for reading control parameters, determining the status of converter groups, executing collaborative control strategies, and communicating with other components in the power grid.

[0148] The first converter group: consists of multiple converters, responsible for converting direct current into alternating current, or performing other power conversion tasks.

[0149] The second converter group: has similar functions to the first converter group, but may be located at a different position in the power grid or undertake different control tasks.

[0150] Grid components: including generators, loads, transmission lines, etc., are the basic components of the power grid.

[0151] In distributed power systems, converters are key devices responsible for converting the power generated by distributed power into a form of power acceptable to the grid. In order to ensure stable operation of the system and efficient energy conversion, precise coordinated control of converters is essential.

[0152] The collaborative control center is an integrated management system that is responsible for collecting, processing and distributing system status information and collaboratively controlling the converters according to preset control parameters. The control center usually consists of two parts: hardware and software. The hardware part includes data acquisition module, communication module and control output module, while the software part includes data processing algorithm and control strategy.

[0153] (1) Data acquisition module The data acquisition module is responsible for collecting the status information of each converter in the system, including parameters such as current, voltage, power, etc. This information is acquired in real time through sensors and measuring devices, and transmitted to the collaborative control center through the communication module.

[0154] (2) Communication module The communication module is responsible for data transmission between the collaborative control center and each converter. It uses a high-speed and reliable communication protocol to ensure the real-time and accuracy of information. The communication module also supports multiple communication methods, such as Ethernet, CAN bus, etc., to meet the needs of different systems.

[0155] (3) Control output module The control output module is responsible for sending the control instructions generated by the collaborative control center to each converter. These instructions are generated based on the preset control parameters and the current system status, and are used to adjust the operating parameters of the converter, such as current, voltage, etc.

[0156] Data processing algorithms and control strategies are the core of the collaborative control center. Based on the collected system status information, it calculates the control parameters of each converter and generates corresponding control instructions. These algorithms and strategies need to be continuously optimized and updated to adapt to system changes and improve control accuracy.

[0157] In a distributed energy system, multiple converters may operate simultaneously, and the interaction and mutual influence between them may lead to system instability. In order to maintain the stability and efficiency of the system, the converters need to be coordinated and controlled. Active power coordinated control and frequency coordinated control are two important methods, which aim to keep the active power and frequency of the system within the preset reference value range by adjusting the output current and voltage of the converter.

[0158] The present invention uses a collaborative control center to read the grid-side operating status, and prioritizes each converter by judging the smoothness and stability of the grid-side operation, setting the startup threshold and startup conditions. The collaborative control center makes startup judgments for two groups of converters, and performs stable and coordinated control of the grid-side frequency, voltage, and active power through the coordinated input of the converters. At the same time, the collaborative control center performs collaborative control by reading the grid-side active power, voltage, and frequency in the current period, avoiding mutual inhibition or even self-excited oscillation between converters of different configurations due to asynchronous operation of the coordination strategy, making the converter operation more stable and reliable. The collaborative control center can perform collaborative control of the two groups of converters according to the configuration, and at the same time adopt a priority control strategy to make each converter be put into operation and adjusted in sequence according to the configured startup sequence during collaborative control, thereby achieving the continuity of the converter operation, which is beneficial to the stability of the grid-side power quality and even the grid frequency of the entire coordinated control system.

[0159] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0160] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the whole or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0161] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A grid-connected converter cooperative control method, characterized in that: Each converter is connected to an AC power grid and is divided into a first converter group and a second converter group. The first converter group is provided with a converter cooperative control center. The grid-type converter cooperative control method includes: Reading the coordinated control parameters of the AC power grid set in the current period through the coordinated control center, wherein the coordinated control parameters include: an active power reference value, a voltage reference value, and a frequency reference value; Determining, by the collaborative control center, whether the first converter group and the second converter group have both started collaborative control; If the first converter group and the second converter group have both started cooperative control, the converters are cooperatively controlled based on the control parameters by the cooperative control center, and the cooperative control includes: active power cooperative control and frequency cooperative control.

2. The grid-connected converter cooperative control method according to claim 1, characterized in that: The determining, by the collaborative control center, whether the first converter group and the second converter group have both started collaborative control includes: Reading the current active power value of each converter in the first converter group and the second converter group respectively through the collaborative control center; Determine whether the current active power value of each converter is greater than the set active power start threshold value, and if both are greater than the set active power start threshold value, start the coordinated control; Determining whether the first converter group and the second converter group both start cooperative control; If the first converter group or the second converter group does not start the coordinated control, reading the grid-side active power value of the converter in the current period; If the grid-side active power value of the converter in the current period is close to the active power reference value, coordinated control is started on the first converter group or the second converter group.

3. The grid-connected converter cooperative control method according to claim 1, characterized in that: The collaborative control of the converter based on the control parameter by the collaborative control center includes: When active power cooperative control is performed on the converter, the first current value and the first voltage value output by each converter in the group are read by the cooperative control center; Calculate the product of the phasor of the first current value and the phasor of the first voltage value and use it as the first active power value output by the converter, and compare the first active power value output by each converter with the active power reference value; When the first active power value output by the converter is less than the active power reference value, the reference current value is reduced to reduce the active output; when the first active power value output by the converter is greater than the active power reference value, the reference current value is increased to increase the active output; when the first active power value output by the converter is equal to the active power reference value, the existing current value is used to keep the active output unchanged.

4. The grid-connected converter cooperative control method according to claim 1, characterized in that: The collaborative control of the converter based on the control parameter by the collaborative control center includes: When frequency cooperative control is performed on the converter, the second current value and the second voltage value output by each converter in the group are read by the cooperative control center; Calculate the product of the phasor of the second current value and the phasor of the second voltage value and use the product as the second active power value output by the converter, and convert the second active power value into a fundamental frequency equivalent value; The base frequency equivalent value is subtracted from the grid-side frequency value of the converter, the subtracted value is multiplied by the base frequency multiple to obtain the voltage phasor, the voltage phasor sum is divided by the current phasor to obtain the AC current value, the AC current value is divided by the base frequency to obtain the AC current base frequency value, the AC current base frequency value is compared with the base frequency, if the AC current base frequency value is greater than the base frequency, the reactive current value output by the converter is reduced, if the AC current base frequency value is less than the base frequency, the reactive current value output by the converter is increased until the grid-side frequency value reaches the frequency reference value.

5. The grid-connected converter cooperative control method according to claim 1, characterized in that: The grid-type converter coordinated control method further includes: Monitoring the operating status of each converter through the collaborative control center; If the grid-side active power value of the current converter is greater than the set startup active power threshold, the grid-side voltage value is less than the voltage startup threshold, or the grid-side frequency value is lower than the frequency startup threshold, the current converter operation state is marked as the startup state; If the current converter fails, the grid-side voltage value is greater than the preset voltage too high threshold, or the grid-side voltage is higher than the preset voltage too low threshold, the current converter operation state is marked as a fault state; If the current converter fault is eliminated or the grid-side voltage value drops below the voltage start threshold again, the current converter operation state is marked as a normal state.

6. The grid-connected converter cooperative control method according to claim 5, characterized in that: The grid-type converter coordinated control method further includes: Determining the operating status of each converter by the collaborative control center; The collaborative control center performs intra-group collaborative control according to the operating status of each converter, and performs inter-group collaborative control according to the operating status of each converter.

7. The grid-connected converter cooperative control method according to claim 6, characterized in that: The determining the operating status of each converter by the collaborative control center includes: The collaborative control center determines whether the current converter is a converter that triggers the start of collaborative control. If so, the output active power of each converter is read to start the collaborative control judgment, otherwise no processing is performed; The collaborative control center determines the operating state of the current converter, and if the current converter is in the startup state, marks it as the startup state, otherwise no processing is performed; Determine whether the current converter is in a fault state through the collaborative control center. If the current converter is in a fault state, mark it as a fault state and determine whether it is an internal fault. Otherwise, do not process it. If the current converter is in a group fault, determine whether the drop in the grid-side frequency value of the current converter exceeds the preset fault threshold. If not, mark it as a group fault, otherwise mark it as a fault state; If the current converter is not in a group fault, it is marked as a normal state. Otherwise, it continues to determine whether the current active power value of the current converter is greater than the active power start threshold. If not, no processing is performed. Otherwise, it is marked as a start state.

8. The grid-connected converter cooperative control method according to claim 7, characterized in that: The performing of intra-group collaborative control by the collaborative control center according to the operating status of each converter includes: When the converter has an internal fault and performs internal coordinated control, if the current converter is marked as a startup state or a fault state, the current converter is controlled to output normally through the coordinated control center until it is marked as a normal state; If the current converter is marked as being in the start-up state, the reference current value is increased and does not exceed the set current limit current; If the current converter is marked as normal, the original control output is maintained until it is marked as fault or start-up.

9. The grid-connected converter cooperative control method according to claim 7, characterized in that: The performing inter-group collaborative control according to the operating status of each converter by the collaborative control center includes: When the converter has an intra-group fault and performs inter-group collaborative control, if the current converter is marked as a startup state, the current converter is controlled to output normally through the collaborative control center until it is marked as a fault or startup state; If the current converter is marked as a fault state, the reference current value is increased and does not exceed the set current state limit current; If the current converter is marked as normal, the original control output is maintained until it is marked as a fault state or a start-up state.

10. A grid-type converter cooperative control system, characterized in that: The grid-type converter collaborative control system includes multiple converters connected to an AC power grid and a collaborative control center of the converters, each converter being divided into a first converter group and a second converter group, and the collaborative control center being arranged in the first converter group; the collaborative control center is used to execute the grid-type converter collaborative control method described in any one of claims 1 to 9.

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