Cooperative control method and system for grid-type converters

Abstract

The present invention relates to the field of converter control technology, and discloses a method and system for cooperative control of a grid-type converter. The method for cooperative control of a grid-type converter comprises: reading the cooperative control parameters of the AC power grid set for the current period through a cooperative control center, the cooperative control parameters including: active power reference value, voltage reference value and frequency reference value; judging through the cooperative control center whether the first converter group and the second converter group have both started cooperative control; if the first converter group and the second converter group have both started cooperative control, the converter is cooperatively controlled based on the control parameters through the cooperative control center, the cooperative control including: active power cooperative control and frequency cooperative control. The present invention realizes the coordinated operation of the interface converter of distributed power sources such as photovoltaic cells and wind power generation and the grid with the grid-side converter, thereby improving the grid connection stability and protecting the safe operation of the grid.

Description

Technical Field

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

[0002] As power system access modules, converters enable various forms of AC / DC power flow interaction through conversion, making them a core component for building high-efficiency power transmission and distribution, as well as smart grids. Traditional converters operate independently, with relatively limited functions and capacities. Their operation is unlikely to meet the unified standards for efficient, stable, and flexible grid operation. The rapid advancement of power electronics has driven the rapid development of digital communication and coordinated control technologies for multiple converters. Multi-converter interconnected systems enable diverse power flow interactions between various converters through flexible topology transformations, providing more options for efficient and flexible grid operation. Depending on the actual topology and control strategy, meshed converter systems can achieve conversion across multiple power levels and complex grid types. They are key equipment for complex large power grids, key user groups, and DC transmission systems, enabling rapid power transmission, efficient power flow regulation, voltage support, and high-quality power supply within regional power grids.

[0003] In recent years, with the large-scale application and continuous development of grid-connected converters, the parallel operation of multiple converters has become increasingly common. However, when multiple converters are connected in parallel, factors such as network delays and environmental factors can lead to asynchronous operation, which in turn causes converter losses 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 collaborative control of grid-type converters, aiming to solve the technical problem that when multiple converters are connected in parallel, they operate asynchronously, thereby causing losses to the converters and affecting the operating performance of the entire system.

[0005] A first aspect of the present invention provides a method for coordinated control of 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. The method for coordinated control of the grid-type converter comprises:

[0006] 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;

[0007] Determining, by the collaborative control center, whether the first converter group and the second converter group have both started collaborative control;

[0008] 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.

[0009] Optionally, in a first implementation 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:

[0010] Reading, through the collaborative control center, a current active power value of each converter in the first converter group and the second converter group respectively;

[0011] Determine whether the current active power value of each converter is greater than the set active power start threshold. If both are greater than the set active power start threshold, start the coordinated control;

[0012] Determining whether the first converter group and the second converter group both start coordinated control;

[0013] If the first converter group or the second converter group does not start coordinated control, reading the grid-side active power value of the converter in the current period;

[0014] 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.

[0015] Optionally, in a second implementation 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:

[0016] When active power collaborative control is performed on the converters, the first current value and the first voltage value output by each converter in the group are read by the collaborative control center;

[0017] Calculating a product of a phasor of the first current value and a phasor of the first voltage value and using the product as a first active power value output by the converter, and comparing the first active power value output by each converter with the active power reference value;

[0018] 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.

[0019] Optionally, in a third implementation 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:

[0020] When frequency coordinated control is performed on the converters, the second current value and the second voltage value output by each converter in the group are read by the coordinated control center;

[0021] Calculating the product of the phasor of the second current value and the phasor of the second voltage value as the second active power value output by the converter, and converting the second active power value into a fundamental frequency equivalent value;

[0022] The fundamental frequency equivalent value is subtracted from the grid-side frequency value of the converter, and the subtracted value is multiplied by the fundamental 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 fundamental frequency to obtain the AC current fundamental frequency value. The AC current fundamental frequency value is compared with the fundamental frequency. If the AC current fundamental frequency value is greater than the fundamental frequency, the reactive current value output by the converter is reduced. If the AC current fundamental frequency value is less than the fundamental frequency, the reactive current value output by the converter is increased until the grid-side frequency value reaches the frequency reference value.

[0023] Optionally, in a fourth implementation of the first aspect of the present invention, the grid-type converter coordinated control method further includes:

[0024] Monitoring the operating status of each converter through the collaborative control center;

[0025] 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 less than the frequency startup threshold, the current converter operation state is marked as startup state;

[0026] 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;

[0027] 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 normal.

[0028] Optionally, in a fifth implementation of the first aspect of the present invention, the grid-type converter coordinated control method further includes:

[0029] Determining the operating status of each converter by the collaborative control center;

[0030] 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.

[0031] Optionally, in a sixth implementation of the first aspect of the present invention, determining the operating status of each converter by the collaborative control center includes:

[0032] 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.

[0033] The collaborative control center determines the current operating state of the converter. If the converter is in the startup state, it is marked as the startup state. Otherwise, no processing is performed.

[0034] The collaborative control center determines whether the current converter is in a fault state. If the current converter is in a fault state, it is marked as a fault state and it is determined whether it is an internal fault in the group. Otherwise, no processing is performed;

[0035] 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;

[0036] If the current converter is not in a group fault, it is marked as normal. Otherwise, it is determined 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 start state.

[0037] Optionally, in a seventh implementation of the first aspect of the present invention, the performing, by the collaborative control center, intra-group collaborative control according to the operating status of each converter includes:

[0038] When the converter has an internal fault and is in group coordinated control, if the current converter is marked as a startup state or a fault state, the coordinated control center controls the current converter to output normally until it is marked as a normal state;

[0039] If the current converter is marked as being in the start-up state, the reference current value is increased without exceeding the set current limit;

[0040] If the current converter is marked as normal, the original control output is maintained until it is marked as fault or startup state.

[0041] Optionally, in an eighth implementation of the first aspect of the present invention, performing inter-group collaborative control according to the operating status of each converter by the collaborative control center includes:

[0042] When a converter has an intra-group fault and inter-group collaborative control is performed, if the current converter is marked as being in the startup state, the collaborative control center controls the current converter to output normally until it is marked as being in the fault or startup state;

[0043] If the current converter is marked as a fault state, the reference current value is increased and does not exceed the set current limit;

[0044] If the current converter is marked as normal, the original control output is maintained until it is marked as a fault state or a startup state.

[0045] The second aspect of the present invention also provides a meshed converter collaborative control system, which includes multiple converters connected to the AC power grid and a collaborative control center of the converters. Each converter is divided into a first converter group and a second converter group. 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.

[0046] In the technical solution provided by this invention, a collaborative control center determines the startup of two groups of converters and, through coordinated converter activation, stabilizes and coordinates grid-side frequency, voltage, and active power. Furthermore, the collaborative control center, located on one group of converters, reads the grid-side active power, voltage, and frequency during the current time period to perform collaborative control. This prevents mutual inhibition and even self-oscillation caused by asynchronous operation between converters of different grid configurations, resulting in more stable and reliable converter operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of a first embodiment of a coordinated control method for grid-type converters according to an embodiment of the present invention;

[0048] Figure 2 Schematic diagram of a second embodiment of the coordinated control method for grid-type converters in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The terms "first," "second," "third," "fourth," and so on (if any) in the description and claims of the present invention and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that shown 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 apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product, or apparatus.

[0050] For ease of understanding, the specific process of the embodiment of the present invention is described below. Figure 1 The first embodiment of the coordinated control method of the grid-type converter in the embodiment of the present invention includes:

[0051] 101. Reading, through the collaborative control center, collaborative control parameters of the AC power grid set for the current period, the collaborative control parameters including: an active power reference value, a voltage reference value, and a frequency reference value;

[0052] In this embodiment, before performing converter coordinated control, converters connected to the AC power grid need to be divided into a first converter group and a second converter group. The first converter group is provided with a converter coordinated control center.

[0053] In this embodiment, before grouping, a grid topology scan is required. Specifically, an impedance scanner is used to inject a high-frequency signal (1-10kHz). The impedance characteristics of the grid nodes are analyzed through FFT. The PMU collects the bus voltage phase difference in real time to generate a dynamic topology map. The scan results are then compared and verified with the SCADA system topology map, with an error requirement of <2%. The SCADA (Supervisory Control And Data Acquisition) system, i.e., the data acquisition and monitoring control system, can obtain the grid topology map, thereby identifying the grid connection point, feeder hierarchy, and adjacent node relationships of each converter. Finally, grouping is performed based on the preset grouping rules:

[0054] 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 close electrical coupling.

[0055] The second group (slave control group): converters distributed at the end of the power grid or in light-load areas.

[0056] The specific grouping method can be calculated using PowerFactory or PSCAD to calculate the electrical distance and verify the rationality of the grouping. In addition, the capacity relationship must also be considered during the grouping process, as follows:

[0057] The total capacity of the master control group ≥ the capacity of the slave control group × 1.2;

[0058] The capacity difference of a single converter is ≤ 10%.

[0059] The master control group includes at least one converter with black start capability and is equipped with a redundant control unit (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.

[0060] Main control group equipment: Install GPS / Beidou dual-mode clock synchronization modules (±1μs accuracy), deploy industrial-grade switches (supporting IEEE 1588 PTP protocol), and build a ring fiber optic network.

[0061] Slave control group equipment: Configured with fast response contactor (action time ≤ 10ms), supporting remote opening and closing control.

[0062] The collaborative control center is deployed in the main control group. The core processor uses an FPGA to implement the communication protocol stack and data preprocessing. The DSP runs the control algorithm with a calculation cycle of ≤100μs. For redundancy, dual power supply modules (AC / DC + supercapacitor energy storage) and mirrored storage units (RAID 1 configuration) are used, with a data update cycle of ≤1ms.

[0063] Communication configuration of collaborative control center:

[0064] Within the main control group: TSN (Time Sensitive Network) is used, with a cycle of 1ms and jitter <50μs.

[0065] Between master and slave groups: Using IEC 61850-8-1 GOOSE protocol, transmission delay is less than 5ms.

[0066] Scheduling system connection: OPC UA over TSN, supporting 1,000 data point updates per second.

[0067] In this embodiment, the collaborative control center communicates with the power grid management system or control center via a pre-defined communication interface (e.g., Ethernet, serial communication, etc.) to obtain collaborative control parameters for the AC power grid set for the current time period. These parameters include, but are not limited to, active power reference values, voltage reference values, and frequency reference values.

[0068] In this embodiment, after obtaining the collaborative control parameters, the collaborative control center first verifies the parameters to ensure their legitimacy and accuracy. This verification process may include checking the parameter's value range and data type. After verification, the parameters are stored in the collaborative control center's memory or database for subsequent use. To ensure the real-time and accuracy of the collaborative control parameters, the collaborative control center needs to update the parameters periodically or based on trigger conditions. Trigger conditions may include the expiration of a time interval, a change in the power grid status, etc. The update process also includes parameter acquisition, verification, and storage.

[0069] 102. Determine, through the collaborative control center, whether the first converter group and the second converter group have both started collaborative control;

[0070] 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, which may include operating status, fault status, control mode, etc.

[0071] Based on the acquired status information, the collaborative control center determines whether collaborative control has been activated for both the first and second converter groups. This determination may include checking whether each converter group is in its preset control mode and whether it has received a collaborative control activation command. If a converter group is detected as abnormal (e.g., not activated, faulty, etc.), the collaborative control center will take appropriate action.

[0072] In one embodiment, the step 102 further includes:

[0073] 1021. Read, through the collaborative control center, a current active power value of each converter in the first converter group and the second converter group;

[0074] The coordinated 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 coordinated control of the converter groups.

[0075] The collaborative control center needs to establish a stable communication link with each converter, typically through a local area network (LAN), wide area network (WAN), or dedicated communication bus (such as CAN bus, Modbus, etc.). The communication protocol should be selected based on the specific equipment and system requirements to ensure reliable and real-time data transmission.

[0076] The collaborative control center sends a command to each converter via a communication link to read the current active power value. The command format must comply with the communication protocol specifications and include information such as the command type, converter identifier, and the read parameter (active power). After receiving the read command, each converter sends its current active power value back to the collaborative control center via the communication link. After receiving the data, the collaborative control center parses the data according to the communication protocol specifications to determine the current active power value of each converter.

[0077] 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 data access and effective management.

[0078] 1022. Determine whether the current active power value of each converter is greater than a set active power start threshold. If both are greater than the set active power start threshold, start coordinated control.

[0079] After obtaining the current active power values ​​of each converter, the collaborative control center determines whether these values ​​are greater than the set active power start threshold to decide whether to initiate collaborative control. A reasonable active power start threshold should be set based on system requirements and device characteristics. When setting the threshold, factors such as device rated power, system stability, and power loss should be considered.

[0080] The collaborative control center compares each converter's current active power value with the set active power activation threshold. If the current active power value exceeds the threshold, the converter is deemed to meet the conditions for initiating collaborative control. The collaborative control center then checks whether all converters in the first and second converter groups meet the condition that their current active power values ​​are greater than the threshold. If all converters meet the conditions, the process proceeds to the next step, initiating collaborative control.

[0081] In this embodiment, the threshold setting should be adjusted according to the actual situation to ensure the accuracy and effectiveness of the collaborative control. During the comparison process, the real-time and accuracy of the data should be considered to avoid misjudgment due to data delay or error.

[0082] 1023. Determine whether the first converter group and the second converter group both start coordinated control;

[0083] After confirming that each converter meets the conditions for initiating coordinated control, the coordinated control center needs to determine whether coordinated control has been initiated for both the first converter group and the second converter group. The coordinated control center can check the coordinated control status flag of each converter or converter group. The status flag is typically a Boolean value or enumeration value that indicates whether coordinated control has been initiated for the converter or converter group.

[0084] The coordinated control center checks the coordinated control status flags of the first converter group and the second converter group respectively. If the status flags of both groups indicate that the coordinated control has been started, it is considered that the coordinated control has been started for both groups.

[0085] 1024. If the first converter group or the second converter group does not start coordinated control, read the grid-side active power value of the converter in the current period;

[0086] If coordinated control is not started in either 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 coordinated control needs to be started.

[0087] The collaborative control center determines the current time period based on the system clock or timestamp. Time periods should be set based on system requirements and operational strategies, such as by hour, minute, or specific time period. The collaborative control center reads the grid-side active power value of each converter during the current time period via a communication connection. The grid-side active power value refers to the active power exchanged between the converter and the grid, reflecting the converter's power output or absorption to the grid.

[0088] The collaborative control center stores the grid-side active power values ​​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 data access and effective management.

[0089] 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.

[0090] 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.

[0091] A reasonable active power reference value is set based on system requirements and operating strategies. This reference value 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 during the current period with the set active power reference value. The comparison result can be expressed as an error value or deviation percentage, reflecting the degree of proximity between the grid-side active power value and the reference value.

[0092] If the error or percentage deviation between the grid-side active power values ​​of all converters and the reference value during the current period is within the set tolerance range (i.e., close to the reference value), coordinated control is considered to be activated. The tolerance range should be set according to system requirements and operating strategies to ensure the accuracy and effectiveness of coordinated control.

[0093] The collaborative control center sends a collaborative control start instruction to the first or second converter group, if collaborative control is not yet enabled. The instruction format should comply with the communication protocol specifications and include information such as the instruction type, converter group identifier, and collaborative control parameters. After collaborative control is enabled, the collaborative control center updates the collaborative control status flags of the first and second converter groups to reflect the current collaborative control status.

[0094] 103. If the first converter group and the second converter group have both started collaborative control, the converters are collaboratively controlled based on the control parameters through the collaborative control center, and the collaborative control includes: active power collaborative control and frequency collaborative control.

[0095] (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.

[0096] For example, active power can be distributed and regulated by adjusting the output voltage amplitude and phase angle of the converter group. The droop factor determines how quickly the converter group responds to power changes.

[0097] For example, by simulating the characteristics of synchronous generators and adjusting parameters such as the inertia and damping of the converter group, the stability and response speed of the power grid can be improved. Alternatively, advanced optimization algorithms (such as genetic algorithms and particle swarm algorithms) can be used to calculate the optimal active power distribution plan based on the real-time status of the power grid and control objectives.

[0098] In this embodiment, parameters such as the output power, grid voltage, and current of the converter group are collected in real time. Based on this collected data and the control strategy, the output power of the converter group to be adjusted is calculated. Finally, the calculated control signal is sent to the converter group to adjust its output power.

[0099] (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.

[0100] For example, frequency regulation and distribution can be achieved by adjusting the relationship between the output frequency and active power of the converter group. The droop factor determines the speed at which the converter group responds to frequency changes.

[0101] Another example is simulating the inertia characteristics of synchronous generators and adjusting the charging and discharging processes of the converter group's energy storage elements (such as capacitors and inductors) to provide additional inertia support and improve grid frequency stability. Alternatively, a fast-response controller (such as a proportional-integral-derivative controller) can be used to quickly adjust the converter group's output frequency based on frequency deviations.

[0102] In this embodiment, the frequency parameters of the power grid are monitored in real time. Based on the monitored frequency parameters and the control strategy, the output frequency of the converter group to be adjusted is calculated. Finally, the calculated control signal is sent to the converter group to adjust its output frequency.

[0103] This embodiment comprehensively considers multiple control objectives, including active power balance, frequency stability, and voltage quality, and employs multi-objective optimization algorithms (such as the weighted sum method and Pareto optimality) to determine the optimal coordinated control strategy. Based on the real-time state of the power grid and changes in control objectives, the coordinated control strategy parameters and algorithms are adaptively adjusted to enhance control flexibility and robustness. A distributed control architecture is employed to distribute coordinated control tasks among multiple controllers or converter groups, improving control response speed and reliability.

[0104] Furthermore, this embodiment can evaluate the effectiveness of the coordinated control strategy by real-time monitoring of grid status parameters (such as active power, frequency, and voltage). Evaluation metrics may include control error, response time, and stability. Based on the evaluation results, the coordinated control strategy is adjusted and optimized. This adjustment process may include modifying control parameters, improving control algorithms, and adding or removing control objectives. Key information from the coordinated control process (such as control parameters, control strategy, and control effectiveness) is recorded and a report is generated for subsequent analysis and improvement.

[0105] The present invention avoids mutual inhibition and even self-oscillation caused by asynchronous operation of coordination strategies between different grid-type converters, making converter operation more stable and reliable. It is beneficial to the stability of grid-side power quality and even grid frequency of the entire coordinated control system.

[0106] In one embodiment, active power coordinated control is performed in the above step 103 in the following manner:

[0107] 1031. When performing active power collaborative control on the converters, read, through the collaborative control center, a first current value and a first voltage value output by each converter in the group;

[0108] Active power collaborative control is one of the core functions of the collaborative control center. It achieves overall system power balance and stability by adjusting the active power output of each converter. The collaborative control center first needs to read the first current and first voltage outputs of each converter group. These values ​​are acquired from each converter in real time by the data acquisition module and transmitted to the collaborative control center via the communication module.

[0109] The data acquisition module in the collaborative control center uses sensors and measuring devices to acquire real-time current and voltage values ​​from each converter. These sensors and measuring devices must possess high precision and stability to ensure data accuracy. The collected current and voltage values ​​are transmitted to the collaborative control center via the communication module. This communication module utilizes a high-speed, reliable communication protocol to ensure real-time and accurate data. Furthermore, the communication module 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 calculations and processing.

[0110] 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;

[0111] After obtaining the current and voltage values ​​for each converter, the phasor product of these values ​​needs to be calculated to obtain the active power output of each converter. The current and voltage values ​​are expressed as phasors, including amplitude and phase. This can be achieved using a phasor measurement unit (PMU) or a phasor transformation algorithm. The dot product of the current phasor and the voltage phasor is performed to obtain the active power value. This process can be implemented using complex multiplication: P = I⋅V∗, where I is the current phasor and V∗ is the conjugate of the voltage phasor. The result of the phasor product is converted to an active power value. This typically involves calculating the square of the amplitude and the cosine of the phase.

[0112] 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.

[0113] After obtaining the active power output values ​​of each converter, these values ​​need to be compared with preset active power reference values ​​to determine whether the converter's active power output needs to be adjusted. Active power reference values ​​are typically set based on system requirements and the output capabilities of the distributed generation (DGs). These values ​​can be set through system configuration parameters or manual input.

[0114] Compare the active power output of each converter with the reference value. This can be achieved by a simple subtraction operation, that is, calculate P 实际 −P 参考Based on the comparison results, the collaborative control center determines whether the active power output of each converter needs to be adjusted. If the actual power is less than the reference value, the active power output needs to be increased; if the actual power is greater than the reference value, the active power output needs to be reduced; if the actual power is equal to the reference value, the current output remains unchanged. Based on the comparison results, the collaborative control center adjusts the reference current value of each converter to control its active power output.

[0115] Based on the comparison results, an appropriate adjustment strategy is formulated. If the actual power is less than the reference value, the reference current value is increased; if the actual power is greater than the reference value, the reference current value is decreased; if the actual power is equal to the reference value, the current reference current value remains unchanged. The adjusted reference current value is sent to each converter. This can be achieved through a control output module, which sends 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 accordingly. This typically involves current control algorithms and PWM modulation techniques.

[0116] During the coordinated active power control process, the output status of each converter must be monitored in real time, with feedback adjustments made based on actual conditions. The data acquisition and communication modules of the coordinated control center monitor each converter's parameters, such as current, voltage, and power, in real time. These parameters reflect the converter's operating status and performance. Control strategies are adjusted based on the real-time monitoring results. If the output status of a converter is found to be abnormal or deviates from preset values, feedback adjustments are required. This can be achieved by modifying control parameters or resetting reference values. Through continuous monitoring and feedback adjustments, the control strategy is optimized and control accuracy is improved. This ensures stable system operation under various operating conditions and achieves efficient energy conversion.

[0117] In one embodiment, frequency coordinated control is performed in step 103 in the following manner:

[0118] 1034. When frequency coordinated control is performed on the converters, the coordinated control center reads the second current value and the second voltage value output by each converter in the group;

[0119] The collaborative control center needs to establish a communication connection with each converter. This can be achieved, for example, through a local area network (LAN), wide area network (WAN), or dedicated communication protocol. The collaborative control center sends a data request to each converter, requesting the current current and voltage values. Upon receiving the request, each converter transmits the current current (recorded as the second current value) and voltage (recorded as the second voltage value) to the collaborative control center via a communication link. The collaborative control center stores the received data in a local database or memory for subsequent calculations and analysis.

[0120] This embodiment requires ensuring that the communication protocols between the collaborative control center and the converters are compatible to ensure accurate data transmission. A unified data format, including data type, length, and units, must be defined to ensure data accuracy and consistency. Furthermore, it is necessary to ensure that the data provided by each converter is synchronized and collected at the same time. This can be achieved by setting a unified sampling interval or using timestamps.

[0121] 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.

[0122] The second current value and the second voltage value are converted from the time domain to the frequency domain to obtain their phasor representations. This is typically achieved using mathematical methods such as Fourier transforms. 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. Because the current and voltage in the grid may contain multiple frequency components, to simplify calculation and analysis, the second active power value needs to be converted to a value equivalent to the fundamental frequency. This is typically achieved using a filter or mathematical transformation to extract the active power component corresponding to the fundamental frequency.

[0123] 1036. Subtract the fundamental frequency equivalent value from the grid-side frequency value of the converter, multiply the subtracted value by a multiple of the fundamental frequency 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 fundamental frequency to obtain the AC current fundamental frequency value, compare the AC current fundamental frequency value with the fundamental frequency, if the AC current fundamental frequency value is greater than the fundamental frequency, reduce the reactive current value output by the converter, if the AC current fundamental frequency value is less than the fundamental frequency, increase the reactive current value output by the converter until the grid-side frequency value reaches the frequency reference value.

[0124] Calculate the difference between the fundamental frequency equivalent value and the grid-side frequency of the converter. This difference reflects the deviation between the current active power and the desired frequency. Then, multiply this difference by a multiple of the fundamental frequency (usually a constant) to obtain the voltage phasor that needs to be adjusted. This voltage phasor indicates the magnitude and direction of the voltage change required to adjust the frequency. The voltage phasor is then divided by the current phasor to obtain the AC current value, which indicates the magnitude and direction of the current change required to adjust the frequency. Finally, divide the AC current value by the fundamental frequency to obtain the AC current fundamental frequency value, which represents the current component corresponding to the fundamental frequency.

[0125] See also Figure 2 , Figure 2This is a second embodiment of the method for collaborative control of a grid-type converter in an embodiment of the present invention. In this embodiment, during the process of collaboratively controlling the converters based on the control parameters by the collaborative control center, the method for collaborative control of the grid-type converter further includes:

[0126] 201. Monitoring the operating status of each converter through the collaborative control center;

[0127] Each converter is equipped with sensors to collect real-time key parameters such as grid-side active power, grid-side voltage, and grid-side frequency. These sensors should be highly accurate and reliable to ensure the collected data is accurate and reliable.

[0128] The converters transmit the collected data to the collaborative control center in real time through built-in communication devices (such as Ethernet interfaces and RS485 interfaces). The collaborative control center should be configured with the appropriate communication interfaces and protocols to ensure that it can correctly receive and process data from each converter.

[0129] The collaborative control center receives data from each converter through a communication interface and stores it in the corresponding data buffer. The collaborative control center preprocesses the received data, including data verification, data filtering, and data conversion. Data verification verifies the integrity and correctness of the data; data filtering removes noise and interference; and data conversion converts the raw data into a format suitable for subsequent processing and analysis.

[0130] The collaborative control center updates the operating status of each converter in real time, including current active power, voltage, and frequency values. This information is displayed graphically or in text format on the monitoring interface, allowing operations and maintenance personnel to view and understand the operating status of each converter in real time.

[0131] 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 less than the frequency startup threshold, then the current operating state of the converter is marked as startup state;

[0132] Based on 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. Based on 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 met one of the startup conditions. Based on 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 met one of the startup conditions.

[0133] 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 state:

[0134] (1) The grid-side active power value is greater than the set start-up active power threshold;

[0135] (2) The grid-side voltage is lower than the voltage start threshold;

[0136] (3) The grid-side frequency value is lower than the frequency start threshold.

[0137] The collaborative control center records information about converters identified as being in the startup state in a log, including the converter number, startup time, and startup conditions. The collaborative control center notifies operations and maintenance personnel of any converters currently in the startup state via text messages, emails, or system messages, allowing them to take timely action and conduct subsequent operations.

[0138] 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;

[0139] Built-in fault detection: The converter is equipped with an internal fault detection module to detect converter faults in real time. The fault detection module can detect circuit faults, overheating faults, overcurrent faults, etc.

[0140] Voltage anomaly detection: The collaborative control center compares each converter's grid-side voltage with preset overvoltage and undervoltage thresholds in real time. If the grid-side voltage exceeds the overvoltage threshold or falls below the undervoltage threshold, the converter is considered to be in a voltage anomaly state.

[0141] 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 high voltage threshold or falls below the low voltage threshold, the current operating state of the converter is marked as a fault state.

[0142] The collaborative control center logs information about converters identified as faulty, including converter number, fault time, fault type (circuit fault, overheating fault, overcurrent fault, overvoltage fault, undervoltage fault, etc.), and fault parameters. The collaborative control center notifies operations and maintenance personnel of converter faults through audible and visual alarms, text messages, emails, or system messages, and provides the fault type and possible cause.

[0143] When possible, the collaborative control center can automatically or manually isolate the faulty converter from the system through the operation and maintenance personnel to prevent the fault from spreading and affecting the normal operation of other equipment.

[0144] 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 normal.

[0145] Fault recovery detection: When a converter fault occurs, the collaborative control center or operation and maintenance personnel can take appropriate measures to repair the fault. After the fault is repaired, the converter's internal fault detection module will re-check the converter's status and confirm whether the fault has been eliminated.

[0146] Voltage recovery detection: When the grid-side voltage of a converter exceeds the overvoltage threshold or falls below the undervoltage threshold, causing the converter to enter a fault state, the collaborative control center monitors changes in the grid-side voltage in real time. When the grid-side voltage returns to within the normal range (i.e., below the voltage start threshold), the abnormal voltage condition is considered resolved.

[0147] Normal status judgment: When one of the following conditions is met, the current converter operation status is marked as normal:

[0148] (1) The internal fault detection module of the converter confirms that the fault has been eliminated;

[0149] (2) The grid-side voltage value of the converter returns to the normal range (i.e., below the voltage starting threshold).

[0150] The Collaborative Control Center logs information about converters deemed normal, including the converter number, recovery time, and recovery conditions. The Collaborative Control Center notifies operations and maintenance personnel via text message, email, or system message that the converter has returned to normal. Once the converter is confirmed to be normal, the Collaborative Control Center can automatically or manually reconnect the converter to the system to restore normal operation.

[0151] In an optional embodiment, during the process of monitoring the operating status of each converter by the collaborative control center, the grid-type converter collaborative control method further includes:

[0152] 205. Determine the operating status of each converter through the collaborative control center;

[0153] Each grid-connected converter is equipped with sensors to collect key operating parameters in real time, such as DC voltage, AC current, grid voltage, grid frequency, active power, reactive power, etc. These sensors should be highly accurate and reliable to ensure the accuracy and reliability of the collected data.

[0154] The converters transmit collected data in real time to the collaborative control center via built-in communication devices (such as Ethernet interfaces and wireless communication modules). The collaborative control center should be configured with appropriate communication interfaces and protocols to ensure that it can correctly receive and process data from each converter.

[0155] 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; and data conversion is used to convert the raw data into a format suitable for subsequent processing and analysis.

[0156] Based on system requirements and converter rated parameters, a series of thresholds are set to determine the converter's operating status. These thresholds include upper and lower limits for DC voltage, AC current, grid voltage, grid frequency, active power, and reactive power.

[0157] The collaborative control center determines the operating status of each converter based on collected data and preset thresholds. Operating status can be categorized as normal, warning, or fault. Normal status indicates that the converter is operating within normal limits; warning status indicates that the converter's operating parameters are approaching or exceeding thresholds, but no fault has occurred; and fault status indicates that the converter has experienced a fault or that operating parameters have significantly exceeded thresholds.

[0158] 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, making it 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 converter's real-time parameters, historical data, status trends and other information. When the converter enters the warning state or fault state, the collaborative control center notifies the operation and maintenance personnel through SMS, email, system messages, 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.

[0159] In an optional embodiment, the above step 205 further includes:

[0160] 2051. 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 determine whether the collaborative control is to be started. Otherwise, no processing is performed.

[0161] The coordinated control center first receives system commands or signals, which may come from a higher-level dispatch system, a local operator interface, or other triggering mechanisms. These commands typically include a specific converter ID or group ID, indicating which converters require coordinated control.

[0162] The collaborative control center verifies the received converter ID against the converter IDs registered in the system. This step ensures that the command is directed to a converter that actually exists in the system, preventing misoperation. If the match is successful and the converter is designated as the one that triggers collaborative control, the collaborative control center proceeds to the next step; otherwise, no collaborative control processing is performed on the converter.

[0163] The collaborative control center and converters use standardized communication protocols (such as Modbus and CANopen) for data transmission, ensuring accuracy and real-time delivery. During data transmission and reception, checksums (such as CRC) are used to detect errors. The collaborative control center records the results of each command reception, matching verification, and startup judgment for subsequent analysis and troubleshooting.

[0164] The collaborative control center sends a data request to the converter designated to initiate collaborative control, requesting it to report its current output active power value. Each converter responds to the collaborative control center's data request and sends its output active power value back to the collaborative control center via a communication protocol. The collaborative control center receives and parses this data, extracting the active power value of each converter. The collaborative control center then determines the active power value of each converter based on pre-set collaborative control activation conditions (such as active power deviation range and total system power demand). If the activation conditions are met, the collaborative control process begins; otherwise, collaborative control is not performed.

[0165] To ensure data synchronization, the collaborative control center sets a unified timestamp when sending data request commands and requires each converter to include this timestamp in its replies, allowing the collaborative control center to synchronize data. Received active power data is filtered to remove noise and outliers, improving data accuracy and reliability. The thresholds for initiating collaborative control should be set based on the actual system conditions, including active power deviation range and total system power demand. These thresholds can be adjusted through the collaborative control center's configuration interface.

[0166] 2052. The collaborative control center determines the current operating state of the converter. If the converter is currently in the startup state, it is marked as the startup state. Otherwise, no processing is performed.

[0167] The collaborative control center periodically or on demand sends status query commands to each converter, requesting it to report its current operating status. Each converter responds to the collaborative control center's status query commands and transmits its operating status back to the collaborative control center via a communication protocol. The collaborative control center receives and parses this data, extracting each converter's operating status information. Based on this parsed operating status information, the collaborative control center determines whether the converter is currently in the startup state. If so, it marks the status as startup and updates the system status table. Otherwise, no action is taken.

[0168] Each converter should use a unified status code to indicate its operating status, such as "operating", "standby", "fault", etc. The collaborative control center makes judgments based on these status codes.

[0169] Status Update: After determining the status of a converter, the Collaborative Control Center (CCC) should promptly update the system status table so that other modules or systems can obtain the latest converter status information. If the CCC does not receive a status response from a converter within the specified time, it will be considered an abnormal state and appropriate exception handling will be performed (such as sending an alarm message and recording a log).

[0170] 2053. Determine, by the collaborative control center, whether the current converter is in a fault state. If the current converter is in a fault state, mark it as a fault state and determine whether it is an intra-group fault. Otherwise, do not process it.

[0171] The Collaborative Control Center monitors the operating status and log records of each converter to detect any faults. Faults may include hardware failures, software failures, or communication failures. If a fault is detected, the Collaborative Control Center further confirms the fault type and severity. This typically involves detailed analysis of fault logs, interaction with other modules, and possible on-site inspections. Based on the fault confirmation results, the Collaborative Control Center marks the converter as faulty and records fault information (such as fault time, fault type, and fault severity) in the fault log.

[0172] Faults should be categorized according to their nature and impact, such as emergency, critical, and general. Different fault types should have different handling processes and priorities. After confirming a fault, the collaborative control center should promptly isolate the faulty converter to prevent it from spreading or impacting the normal operation of other converters. The collaborative control center should promptly notify relevant personnel or systems of the fault so they can respond quickly and take necessary remedial measures.

[0173] 2054. If the current converter has an internal fault, determine whether the grid-side frequency value of the current converter has decreased by more than a preset fault threshold. If not, mark it as an internal fault; otherwise, mark it as a fault state.

[0174] The collaborative control center continuously monitors the grid-side frequency of each converter to provide real-time insights into the grid's operating status. If a converter is marked as having a group-internal fault (i.e., it logically belongs to the same group as other converters, and other converters within the group have also experienced a fault), the collaborative control center compares the converter's current grid-side frequency with a preset fault threshold. If the current grid-side frequency drops by more than the preset fault threshold, the converter is deemed to have a significant impact on grid stability and should be marked as a severe group-internal fault. Otherwise, it remains marked as an group-internal fault.

[0175] Preset fault thresholds should be set based on the actual grid conditions and stability requirements. These thresholds can be adjusted through the Collaborative Control Center's configuration interface. In addition to directly comparing the current frequency value with the threshold, the Collaborative Control Center can also analyze frequency trends (such as rate of change and fluctuation range) to more comprehensively assess the fault's impact on the grid. For severe faults within a group, the Collaborative Control Center should promptly isolate the faulty converter and attempt to restore grid stability. Simultaneously, the center should notify relevant personnel or systems to conduct fault investigation and repair.

[0176] 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.

[0177] 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 based on 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 system's power regulation and distribution. At this point, the collaborative control center marks it as being in 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 system power regulation and should continue to be marked as a faulty state and perform corresponding fault handling.

[0178] For converters marked as faulty, the Collaborative Control Center will take appropriate action based on the fault type and severity, such as issuing an alarm, attempting to restart the converter, or isolating the faulty converter. The Collaborative Control Center will also record the fault handling process and results in a fault log for subsequent analysis and improvement. Active power startup thresholds should be set based on actual system requirements and converter capabilities. These thresholds can be adjusted through the Collaborative Control Center's configuration interface.

[0179] For converters marked as enabled but faulty, the collaborative control center should employ appropriate collaborative control strategies to adjust their output power. These strategies may include power allocation algorithms, current limiting control algorithms, and other algorithms. After implementing fault resolution measures, the collaborative control center should continuously monitor the status of the faulty converter and verify that the fault has been successfully resolved. If the fault persists, appropriate resolution measures should be implemented. If the fault has been resolved, the system status table should be updated and the relevant personnel or systems should be notified.

[0180] 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.

[0181] (1) Intra-group collaborative control

[0182] Based on system requirements and factors such as the converter's location and functional characteristics, multiple converters are divided into different control groups. Converters within each control group have similar operating characteristics and control requirements. Control objectives are set for each control group, including active power distribution, reactive power compensation, voltage regulation, and frequency regulation. Control objectives should be adjusted and optimized based on system needs and grid requirements.

[0183] Based on the control objectives and the operating status of the converters, a coordinated control strategy within the group is developed. This control strategy can include droop control, virtual synchronous generator control, and power split control. Droop control automatically distributes power by adjusting the converter's output impedance and droop coefficient. Virtual synchronous generator control simulates the operating characteristics of synchronous generators to achieve voltage and frequency stability. Power split control uses an optimization algorithm to distribute the output power of each converter.

[0184] Based on the established control strategy, the collaborative control center sends control commands to the converters within each control group. The converters adjust their output parameters based on the received control commands to achieve the group's collaborative control objectives. Simultaneously, the collaborative control center monitors the operating status and control effectiveness of each converter in real time, making adjustments and optimizations as needed.

[0185] In an optional embodiment, the step 206 of performing intra-group collaborative control by the collaborative control center according to the operating status of each converter further includes:

[0186] 2061. When a converter has an internal fault and is performing internal coordinated control, if the current converter is marked as a startup state or a fault state, the coordinated control center controls the current converter to output normally until it is marked as a normal state;

[0187] The collaborative control center first identifies which converters are experiencing intra-group faults through real-time monitoring and data analysis. This typically involves a comprehensive assessment of converter operating 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 immediately initiates the intra-group collaborative control program to optimize energy distribution and regulation within the faulty group, ensuring overall system stability.

[0188] The collaborative control center examines the current status flags of each converter in the group. For converters marked as starting or faulted, the collaborative control center adopts specific control strategies. For converters in the starting state, even though they may be affected by a fault, the collaborative control center attempts to maintain normal output by adjusting control parameters (such as voltage and current reference values). This ensures that as much energy as possible can be effectively utilized during a fault, while also reducing system instability.

[0189] For converter faults, the Collaborative Control Center first assesses the fault type and severity. If the fault does not affect the converter's basic output functions, the Collaborative Control Center attempts to restore normal operation through software repairs or control strategy adjustments. If the fault is severe and cannot be repaired immediately, the Collaborative Control Center places the converter in standby mode, awaiting further repair or replacement.

[0190] Based on the established control strategy, the collaborative control center sends control instructions to each converter within the group, adjusting its output parameters to meet the requirements of group collaborative control. During control instruction execution, the collaborative control center continuously monitors the operating status and output parameters of each converter to ensure the expected control results. Once a converter returns to normal (i.e., the fault is repaired or system stability is restored), the collaborative control center updates its status flag and adjusts the control strategy accordingly.

[0191] 2062. If the current converter is marked as being in the startup state, the reference current value is increased without exceeding the set current limit;

[0192] The collaborative control center first confirms that the converter is in the startup state and assesses its current current demand and output capacity. This assessment may involve analyzing the converter's historical data, forecasting grid load, and considering the status of other converters. Based on the assessment results, the collaborative control center calculates a new reference current value designed to increase the converter's output capacity while ensuring that it does not exceed its set current limit. The purpose of setting the current limit is to protect the converter from overload damage while ensuring overall system stability.

[0193] The collaborative control center sends the new reference current value as a control instruction to the converter, instructing it to adjust its output current to match the new reference value. During the execution of the control instruction, the collaborative control center continuously monitors the converter's operating status and output parameters to ensure that the control effect meets expectations and does not cause new faults.

[0194] The current limiting strategy employed by the collaborative control center should be dynamically adjusted based on the actual output capacity of the converter and the grid load demand. This can be achieved through real-time monitoring and analysis of system data. To improve control accuracy and responsiveness, the collaborative control center may employ advanced control algorithms such as PID control, fuzzy control, or neural network control. When adjusting the reference current value, the collaborative control center should consider the potential risk of failure and implement appropriate preventive measures, such as setting overcurrent and overheating protection.

[0195] 2063. If the current converter is marked as normal, the original control output is maintained until it is marked as fault or startup state.

[0196] The Collaborative Control Center first confirms that the converter is in a normal state—that is, its operating status is stable, its output parameters meet system requirements, and there are no faults or anomalies. Once the converter is confirmed to be normal, the Collaborative Control Center maintains its original control output to ensure system stability and continuity.

[0197] Even though the converter is operating normally, the collaborative control center must continuously monitor its operating status and output parameters to prevent possible failures or anomalies. If the collaborative control center detects any signs that may cause a change in the converter's status (such as voltage fluctuations, current anomalies, etc.), it will immediately activate the early warning mechanism and take appropriate preventive measures. If the converter's status changes (such as from normal to faulty or startup), the collaborative control center will promptly update its status flag and adjust the control strategy based on the new status. Adjusting the control strategy may involve recalculating and adjusting parameters such as reference current and voltage reference values ​​to ensure that the system maintains stable operation in the new state.

[0198] The collaborative control center uses high-precision sensors and advanced signal processing technology to monitor the operating status and output parameters of the converters in real time. These technologies provide accurate and reliable data support, helping the collaborative control center make informed decisions. The collaborative control center employs early warning algorithms based on data analysis and machine learning to predict potential failures or anomalies. These algorithms identify potential failure risks based on changing trends in historical and real-time data and enable proactive preventive measures. The collaborative control center's control strategy should be highly flexible and scalable to adapt to diverse system environments and operating conditions. This can be achieved through a modular design approach and configurable control parameters.

[0199] (2) Inter-group collaborative control

[0200] System-level control objectives are set based on the needs of the entire distributed energy system and the requirements of the power grid. These objectives may include total active power output, total reactive power compensation, system voltage stability, system frequency stability, etc. Inter-group coordinated control strategies are developed based on the system-level control objectives and the operating status of each control group. Inter-group coordinated control strategies may include power balancing control, voltage coordination control, and frequency coordination control. Power balancing control balances the total system power by adjusting the output power of each control group; voltage coordination control stabilizes the system voltage by adjusting the voltage output of each control group; and frequency coordination control stabilizes the system frequency by adjusting the frequency response of each control group.

[0201] Based on the established inter-group collaborative control strategy, the collaborative control center generates corresponding control instructions and sends them to each control group. Control instructions can 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 objectives. The collaborative control center monitors the operating status and control effect of each control group in real time and provides feedback adjustments as needed. If the operating status of a control group deviates from the preset range or the control effect is unsatisfactory, the collaborative control center can promptly adjust its control strategy or send coordination instructions to other control groups to achieve more stable system operation.

[0202] In an optional embodiment, the performing of inter-group collaborative control by the collaborative control center according to the operating status of each converter in step 206 further includes:

[0203] 2064. When a converter has an intra-group fault and inter-group coordinated control is performed, if the current converter is marked as being in the startup state, the coordinated control center controls the current converter to output normally until it is marked as being in the fault or startup state;

[0204] Inter-group collaborative control refers to the unified management and optimized control of multiple converter groups within a distributed energy system through a collaborative control center. This approach aims to achieve efficient energy distribution, stable system operation, and rapid fault response. This control approach considers the mutual influences and constraints between different converter groups, developing an optimal control strategy through comprehensive analysis and decision-making.

[0205] Sensors and monitoring equipment collect real-time operating status data from each converter, preprocessing and cleaning it to ensure data accuracy and reliability. This collected data is analyzed in depth to identify each converter's current status (such as startup, fault, and normal status), triggering appropriate control strategies based on these status changes. Based on the status monitoring results and the objectives of inter-group collaborative control, specific control strategies are formulated, and control instructions are sent to each converter group via a communication protocol. The effectiveness of the control strategy is evaluated in real time, and feedback data is collected for continuous optimization and improvement.

[0206] The collaborative control center first identifies converters experiencing intra-group faults by monitoring and analyzing each converter's operating status data in real time. This typically 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 immediately initiates inter-group collaborative control procedures to optimize energy distribution and regulation between the faulty group and its adjacent groups.

[0207] The collaborative control center checks the current status flags of the faulty converters within the group. For converters marked as enabled, even though they may be affected by the group fault, the collaborative control center attempts to maintain normal output by adjusting control parameters (such as voltage and current reference values). This step aims to maximize available energy within the faulty group while ensuring system stability and minimizing the fault's impact on overall system performance.

[0208] The collaborative control center converts the formulated control strategy into specific control instructions and sends them to the current converter via a communication protocol. During the execution of the control instructions, the collaborative control center continuously monitors the current converter's operating status and output parameters to ensure that the control effect meets expectations. If the current converter's status changes (for example, from startup to fault), the collaborative control center immediately updates its status flag and adjusts the control strategy based on the new status.

[0209] The Collaborative Control Center employs advanced fault detection algorithms, such as machine learning-based anomaly detection and physical model-based fault diagnosis, to improve the accuracy and timeliness of fault identification. While maintaining normal converter output, the Collaborative Control Center dynamically adjusts control parameters based on the system's real-time operating and historical data to ensure system stability and efficiency. Communication between the Collaborative Control Center and the converters utilizes standardized protocols (such as Modbus and CANopen), equipped with appropriate data encryption and verification mechanisms to ensure data security and integrity.

[0210] 2065. If the current converter is marked as a fault state, the reference current value is increased without exceeding the set current limit;

[0211] 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 will analyze the current value required by the current converter in the fault state to determine whether the reference current value needs to be increased to improve its output capacity. The collaborative control center will calculate 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 intended to improve 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.

[0212] When increasing the reference current value, the collaborative control center comprehensively considers the actual output capacity of the current converter, the system load requirements, and the impact of faults on the system, ensuring that the adjusted current value meets system requirements without causing damage to the converter. To improve control accuracy and response speed, the collaborative control center may employ advanced control algorithms such as PID control, fuzzy control, or neural network control. These algorithms can dynamically adjust and optimize based on the system's real-time operating data and historical data. While increasing the reference current value, the collaborative control center monitors the current converter's operating status and output parameters in real time. If any abnormal changes or potential fault risks are detected, the collaborative control center will immediately take appropriate preventive measures, such as reducing output current or activating protection mechanisms.

[0213] 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 startup state.

[0214] The collaborative control center first confirms that the converter is operating normally—that is, its operating status is stable, its output parameters meet system requirements, and there are no faults or anomalies. Once the converter is confirmed to be operating normally, the collaborative control center maintains its original control output to ensure system stability and continuity. Although the converter is operating normally, the collaborative control center continues to monitor its operating status and output parameters to prevent potential faults or anomalies.

[0215] The collaborative control center utilizes advanced early warning algorithms and data analysis technologies to conduct real-time assessment and analysis of the converter's operating status. If any abnormal changes or potential failure risks are detected, the early warning mechanism is immediately activated and appropriate preventive measures are implemented. If the converter's status changes (for example, from normal to faulty or startup), the collaborative control center promptly updates its status flag and adjusts the control strategy based on the new state. These control strategy adjustments may involve recalculating and adjusting parameters such as reference current and voltage values ​​to ensure stable system operation under the new conditions.

[0216] The collaborative control center uses high-precision sensors and advanced signal processing technologies to monitor the operating status and output parameters of the converters in real time. These technologies provide accurate and reliable data support, helping the collaborative control center make informed decisions. The collaborative control center employs early warning algorithms based on data analysis and machine learning to predict potential failures or anomalies. These algorithms identify potential failure risks based on changing trends in historical and real-time data and proactively implement preventative measures. The collaborative control center's control strategies should be highly flexible and scalable to adapt to diverse system environments and operating conditions. This can be achieved through a modular design approach and configurable control parameters. Furthermore, the collaborative control center should possess self-learning and optimization capabilities, dynamically adjusting and optimizing control strategies based on the system's real-time operating data and historical data.

[0217] 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 for the converters. 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 embodiments.

[0218] In distributed energy systems, grid-connected converters are key devices that connect distributed power sources to the power grid. Their operating status and control strategies directly impact the system's stability, efficiency, and reliability. To achieve more efficient and stable system operation, coordinated control between grid-connected converters is crucial. Traditional independent control methods are no longer able to meet the high power quality and stability requirements of modern power grids. Therefore, a coordinated control strategy is needed to optimize overall system performance through centralized management of multiple converters. At the core of this strategy, the coordinated control center receives system status information and coordinates the converters according to preset control parameters to achieve stable system operation and efficient energy conversion.

[0219] In distributed energy systems, converters are key components responsible for converting various forms of energy into electricity and injecting it into the grid. To ensure stable system operation and efficient energy management, a coordinated control center (CCC) plays a crucial role. By monitoring and adjusting the operating status of each converter, the CCC optimizes energy distribution and rapidly responds to system faults. The following details how the CCC determines the operating status of each converter, covering the entire process from initiating coordinated control to handling faults. As the central processor, the CCC collects operating status data from each converter and performs status assessment and management based on pre-set thresholds and logic. The converters, as monitored objects, use built-in sensors to collect key parameters such as grid-side active power, grid-side voltage, and grid-side frequency in real time, and transmits this data to the CCC via communication equipment.

[0220] The meshed converter collaborative control system primarily consists of a collaborative control center, a primary converter group, a secondary converter group, and other possible grid components (such as generators and loads). The collaborative control center, as the core, is responsible for reading control parameters, determining converter group status, and executing collaborative control strategies.

[0221] Collaborative control center: Responsible for reading control parameters, determining the status of the converter group, executing collaborative control strategies, and communicating with other components in the power grid.

[0222] The first converter group: consists of multiple converters, responsible for converting DC power into AC power or performing other power conversion tasks.

[0223] The second converter group has similar functions to the first converter group, but may be located at a different location in the power grid or have different control tasks.

[0224] Grid components: including generators, loads, transmission lines, etc., are the basic components of the power grid.

[0225] In distributed power systems, converters are key components responsible for converting the electrical energy generated by distributed power sources into a form acceptable to the grid. Precise and coordinated control of converters is crucial to ensure stable system operation and efficient energy conversion.

[0226] The collaborative control center is an integrated management system responsible for collecting, processing, and distributing system status information and implementing coordinated control of the converters according to preset control parameters. The control center typically consists of two components: hardware and software. The hardware includes data acquisition modules, communication modules, and control output modules, while the software includes data processing algorithms and control strategies.

[0227] (1) Data acquisition module

[0228] The data acquisition module is responsible for collecting status information of each converter in the system, including parameters such as current, voltage, and power. This information is acquired in real time through sensors and measuring devices and transmitted to the collaborative control center through the communication module.

[0229] (2) Communication module

[0230] The communication module is responsible for data transmission between the collaborative control center and each converter. It uses a high-speed, reliable communication protocol to ensure real-time and accurate information. The communication module also supports multiple communication methods, such as Ethernet and CAN bus, to meet the needs of different systems.

[0231] (3) Control output module

[0232] The control output module is responsible for sending control commands generated by the collaborative control center to each converter. These commands are generated based on preset control parameters and the current system status and are used to adjust converter operating parameters such as current and voltage.

[0233] Data processing algorithms and control strategies are the core of the collaborative control center. Based on collected system status information, they calculate the control parameters of each converter and generate corresponding control instructions. These algorithms and strategies need to be continuously optimized and updated to adapt to system changes and improve control accuracy.

[0234] In distributed energy systems, multiple converters may operate simultaneously. Interactions and mutual influences between them can lead to system instability. To maintain system stability and efficiency, converter coordinated control is necessary. Active power coordinated control and frequency coordinated control are two important approaches. These aim to maintain the system's active power and frequency within preset reference ranges by adjusting the converter's output current and voltage.

[0235] 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 performs startup judgments on two groups of converters, and through the coordinated input of the converters, performs stable and coordinated control of the grid-side frequency, voltage, and active power. 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-oscillation caused by the asynchronous operation of the coordination strategy between converters of different configurations, 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 enable each converter to be put into operation and adjusted in sequence according to the configured startup sequence during collaborative control, thereby achieving continuity in the converter operation, which is beneficial to the grid-side power quality and even the stability of the grid frequency of the entire coordinated control system.

[0236] Those skilled in the art will 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.

[0237] If the integrated unit is implemented as 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, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0238] 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 above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can 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 coordinated control method for grid-type converters, 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 collaborative control center. The grid-type converter collaborative control method includes: 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; 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 by the cooperative control center based on the cooperative control parameters, where the cooperative control includes active power cooperative control and frequency cooperative control; The determining, by the collaborative control center, whether the first converter group and the second converter group have both started collaborative control includes: Reading, through the collaborative control center, a current active power value of each converter in the first converter group and the second converter group respectively; Determine whether the current active power value of each converter is greater than the set active power start threshold. If both are greater than the set active power start threshold, start the coordinated control; Determining whether the first converter group and the second converter group both start coordinated 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, starting coordinated control of the first converter group or the second converter group; 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 less than the frequency startup threshold, the current converter operation state is marked as 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 lower 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 drops below the voltage start threshold again, the current converter operation status is marked as normal; 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.

2. The coordinated control method of grid-type converters according to claim 1, characterized in that: The determining of 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 current operating state of the converter. If the converter is in the startup state, it is marked as the startup state. Otherwise, no processing is performed. The collaborative control center determines whether the current converter is in a fault state. If the current converter is in a fault state, it is marked as a fault state and it is determined whether it is an internal fault in the group. Otherwise, no processing is performed; If the current converter is in a group fault, determine whether the grid-side frequency value of the current converter drops by more than the preset fault threshold. If so, 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 further determined whether the current active power value of the current converter is greater than the active power start threshold. If so, no processing is performed; otherwise, it is marked as a start state.

3. The coordinated control method of grid-type converters according to claim 2, 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 is in the group coordinated control, if the current converter is marked as a fault state, the current converter is controlled by the coordinated control center to output normally 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 without exceeding the set current limit; If the current converter is marked as normal, the original control output is maintained until it is marked as fault or startup state.

4. The coordinated control method of grid-type converters according to claim 2, characterized in that: The performing inter-group collaborative control according to the operating status of each converter by the collaborative control center includes: When a converter has an intra-group fault and inter-group collaborative control is performed, if the current converter is marked as being in the startup state, the collaborative control center controls the current converter to output normally until it is marked as being in the fault state; If the current converter is marked as a fault state, the reference current value is increased and does not exceed the set current limit; If the current converter is marked as normal, the original control output is maintained until it is marked as a fault state or a startup state.

5. The coordinated control method of grid-type converters according to claim 1, characterized in that: The collaborative control of the converter based on the collaborative control parameters by the collaborative control center includes: When active power collaborative control is performed on the converters, the first current value and the first voltage value output by each converter in the group are read by the collaborative control center; Calculating a product of a phasor of the first current value and a phasor of the first voltage value and using the product as a first active power value output by the converter, and comparing 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 increased to increase 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 reduced to reduce 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.

6. A grid-type converter cooperative control system, characterized in that: The grid-type converter collaborative control system includes multiple converters connected to the AC power grid and a collaborative control center of the converters, 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 grid-type converter collaborative control method described in any one of claims 1-5.

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