Test system and control method for grid-forming converter accessing complex power system

Abstract

The application discloses a test system of grid-connected converter accessing a complex power system and a control method thereof, and belongs to the technical field of converter testing. The system comprises a real-time simulation module, a semi-physical grid-connected converter controller, a physical grid-connected converter and a controllable converter. The application builds a preset complex power system model through the real-time simulation module, and combines the controllable converter to enable the test system to simulate the grid environment of a real complex power system, thereby being beneficial to testing the performance of the measured grid-connected converter under the complex power system. Moreover, the semi-physical grid-connected converter controller is combined with the primary system model to form a semi-physical grid-connected converter, and the semi-physical grid-connected converter and the physical grid-connected converter jointly constitute the measured grid-connected converter, realizing large-scale hybrid simulation of the semi-physical and physical, improving the convenience of building the test system, and providing a basis for carrying out complete grid-connected characteristic testing and system-level characteristic testing research of the grid-connected converter.

Description

Technical Field

[0001] This application relates to the technical field of converter testing, and in particular to a testing system and control method for grid-connected converters connected to complex power systems. Background Technology

[0002] As a controlled voltage source, the grid-connected converter can autonomously construct its internal potential and exhibit excellent self-synchronization performance without a phase-locked loop. This makes it play a crucial role in the stability control of the power grid, including frequency regulation, voltage regulation, and oscillation suppression. To ensure that the grid-connected converter can effectively support the power grid, it must undergo detailed testing before being connected to the actual grid.

[0003] However, actual large power grid systems contain a large number of new energy generators, various loads, synchronous generators, grid-connected converters, transformers, and transmission lines, with system capacity reaching gigawatts (GW). Because grid-connected converters need to be adapted to such large-capacity and complex power systems, their testing needs to be carried out in a test system that simulates such a large-capacity and complex power system. However, setting up such a test system is quite complicated. Summary of the Invention

[0004] This application provides a test system and control method for connecting a grid-type converter to a complex power system, which improves the convenience of building a test system for simulating a large-capacity complex power system.

[0005] In a first aspect, embodiments of this application provide a test system for grid-connected converters connected to complex power systems, applied to the testing process of grid-connected converters under test in complex power systems. The test system includes:

[0006] The real-time simulation module is used to construct interconnected pre-set complex power system models and semi-physical grid-type converter primary system models, and to output modulation signals based on the pre-set complex power system models, semi-physical AC signals, and physical AC signals.

[0007] A semi-physical grid-type converter controller is connected to a semi-physical grid-type converter primary system model to form a semi-physical grid-type converter. The semi-physical grid-type converter controller is used to control the semi-physical grid-type converter primary system model so that the semi-physical grid-type converter primary system model outputs a semi-physical AC signal to a preset complex power system model.

[0008] A physical grid-type converter is connected to a pre-set complex power system model. The physical grid-type converter is used to output physical AC signals from the AC port to the pre-set complex power system model.

[0009] The controllable converter is connected to a preset complex power system model and a physical grid-type converter respectively. The controllable converter is used to modulate based on the modulation signal to output the first electrical signal to the AC port of the physical grid-type converter.

[0010] Among them, the semi-physical grid converter and the physical grid converter together constitute the grid converter under test.

[0011] In some embodiments, the real-time simulation module is also used to construct a physical grid-type converter interface model, which is connected to a preset complex power system model, the AC port of the physical grid-type converter, and the controllable converter, respectively.

[0012] The physical grid-type converter interface model is used to process the physical AC signal using the first aggregation method and output it to the preset complex power system model; and the physical grid-type converter interface model is used to output the modulated signal to the controllable converter.

[0013] In some embodiments, physical alternating current signals include physical alternating current signals;

[0014] The physical grid-type converter interface model includes:

[0015] The aggregation unit is connected to the AC port of the preset complex power system model and the physical grid-type converter, respectively. The aggregation unit is used to process the physical AC current signal using the first aggregation method and output it to the preset complex power system model.

[0016] In some embodiments, the primary system model of the semi-physical grid converter is also used to process the semi-physical AC signal using a second aggregation method and output it to a preset complex power system model.

[0017] In some embodiments, the testing system further includes:

[0018] The coordination controller is connected to both the semi-physical grid converter controller and the physical grid converter. Based on the operating status of the semi-physical grid converter, the operating status of the physical grid converter, and the preset power command, the coordination controller determines the corresponding power command for each of the two converters and sends the power command to the corresponding semi-physical grid converter controller and physical grid converter.

[0019] In some embodiments, the coordination controller includes a main coordination controller and a plurality of sub-coordination controllers, the main coordination controller being connected to each sub-coordination controller, and any one of the sub-coordination controllers being connected to a semi-physical grid converter controller and / or a physical grid converter.

[0020] In some embodiments, the real-time simulation module is used to output a modulated signal based on a preset complex power system model, a semi-physical AC signal, and a physical AC signal, including:

[0021] Construct a pre-defined complex power system model, which includes complex power models under various pre-defined operating conditions;

[0022] Based on the complex power model, semi-physical AC signal, and physical AC signal under each preset operating state, the modulated signal corresponding to the complex power model under each preset operating state is output.

[0023] In some embodiments, the testing system further includes:

[0024] A DC power supply is connected to the DC side of the physical grid converter. The DC power supply is used to provide a second electrical signal to the DC side of the physical grid converter.

[0025] In some embodiments, the real-time simulation module includes:

[0026] The real-time simulation interface board connects the semi-physical grid-type converter controller to the primary system model of the semi-physical grid-type converter, while the physical grid-type converter connects to a preset complex power system model through the real-time simulation interface board.

[0027] Secondly, this application also provides a control method for a test system for grid-connected converters connected to complex power systems, the control method comprising:

[0028] Start the real-time simulation module. The real-time simulation module is used to build an interconnected pre-set complex power system model and a semi-physical grid-type converter primary system model, and output a modulation signal based on the pre-set complex power system model, the semi-physical AC signal and the physical AC signal.

[0029] Start the semi-physical grid converter controller. The semi-physical grid converter controller is used to control the primary system model of the semi-physical grid converter so that the primary system model of the semi-physical grid converter outputs a semi-physical AC signal to the preset complex power system model.

[0030] Start the controllable converter, which is used to modulate based on the modulation signal to output the first electrical signal to the AC port of the physical grid converter;

[0031] Start the physical grid-type converter. The physical grid-type converter is used to output the physical AC signal from the AC port to the preset complex power system model.

[0032] The preset complex power system model includes complex power models under various preset operating states; the real-time simulation module outputs the modulation signal corresponding to the complex power model under each preset operating state based on the complex power model, semi-physical AC signal, and physical AC signal.

[0033] This application provides a test system for connecting a grid-connected converter to a complex power system. The test system includes a real-time simulation module, a semi-physical grid-connected converter controller, a physical grid-connected converter, and a controllable converter. The real-time simulation module is used to construct a preset complex power system model and a primary system model of the semi-physical grid-connected converter. The preset complex power system model allows the test system to simulate the grid environment of a real complex power system, thus facilitating the testing of the grid-connected converter under test in complex power systems. Furthermore, the semi-physical grid-connected converter controller is combined with the primary system model to form a semi-physical grid-connected converter. The semi-physical grid-connected converter and the physical grid-connected converter together constitute the grid-connected converter under test, enabling large-scale hybrid simulation of the semi-physical and physical grid-connected converters. This improves the convenience of building a test system for simulating large-capacity complex power systems and provides a foundation for conducting research on the complete testing of the grid-connected converter's grid characteristics and system-level characteristic testing.

[0034] This application also provides a control method for a test system for grid-connected converters connected to complex power systems. This method is applied to the test system for grid-connected converters connected to complex power systems, and thus the control method for the test system for grid-connected converters connected to complex power systems includes all the features of the test system for grid-connected converters connected to complex power systems. These effects will not be elaborated here. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A structural block diagram of a test system for connecting a grid-type converter to a complex power system, provided in an embodiment of this application;

[0037] Figure 2 A structural block diagram of another test system for connecting a grid-type converter to a complex power system provided in this application embodiment;

[0038] Figure 3 A simulation diagram of a semi-physical network converter provided for embodiments of this application;

[0039] Figure 4 A schematic diagram of the physical grid-type converter interface model provided in the embodiments of this application;

[0040] Figure 5 A simplified structural diagram illustrating the connection of multiple semi-physical and physical grid-type converters to a complex power system, as provided in the embodiments of this application;

[0041] Figure 6 A schematic diagram of a control method for a test system for connecting a grid-type converter to a complex power system, provided in an embodiment of this application;

[0042] Figure 7 The semi-physical and physical grid-type converters provided in the embodiments of this application are schematic diagrams of complex power system topologies when energy storage converters are connected. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0044] In the embodiments of this application, "at least one" refers to one or more; "multiple" refers to two or more. In the description of this application, the terms "first," "second," "third," etc., are used only for the purpose of distinguishing descriptions and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implying order.

[0045] References such as “one embodiment” or “some embodiments” as described in this specification mean that one or more embodiments of this application include the specific features, structures, or characteristics described in connection with that embodiment. Therefore, the terms “comprising,” “including,” “having,” and variations thereof, in this specification, mean “including, but not limited to,” unless otherwise specifically emphasized.

[0046] It should be noted that in the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. In addition, unless otherwise specified, the character " / " generally indicates that the associated objects before and after it are in an "or" relationship.

[0047] It should be noted that in the embodiments of this application, "connection" can be understood as an electrical connection, where the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components. In addition, "connection" can also be understood as a signal connection, which means that signal transmission occurs between the two without involving a physical connection.

[0048] In recent years, with the continuous increase in my country's installed capacity of new energy sources and the increasing penetration rate of new energy in the power system, the inertia and grid strength of the power system have been continuously decreasing, posing a huge challenge to the stable operation of the power system. As a controlled voltage source, the grid-connected converter has the ability to build its own internal potential and can have good self-synchronization performance under conditions without phase-locked loops. It plays an important role in the stable control of the system, such as frequency regulation, voltage regulation, and system oscillation suppression.

[0049] As a controlled voltage source, the grid-connected converter can autonomously construct its internal potential and exhibit excellent self-synchronization performance without a phase-locked loop. This makes it play a crucial role in the stability control of the power grid, including frequency regulation, voltage regulation, and oscillation suppression. To ensure that the grid-connected converter can effectively support the power grid, it must undergo detailed testing before being connected to the actual grid.

[0050] To ensure the grid-connected converter's support function for the actual power grid, it must undergo detailed testing before being connected. While grid-connected converter testing can be conducted using test vehicles or third-party certified testing platforms, these methods cannot realistically simulate the operating and fault characteristics of a large-scale power grid. They also cannot test the interaction between the grid-connected converter and the grid, thus failing to effectively test the converter's actual response and support function within the real power grid.

[0051] In real-world large power grids, the system comprises numerous new energy generating units, various types of loads, synchronous generators, grid-connected converters, transformers, transmission lines, and collector lines, with system capacity reaching GW levels or higher. To effectively support this complex power grid system, grid-connected converters require large-scale integration into testing systems, increasing the complexity of these systems and making the construction of testing systems for simulating large-capacity, complex power systems quite cumbersome. Therefore, during the testing of grid-connected converters, two key challenges remain: how to simulate the response characteristics of the actual power grid to provide a more realistic testing environment, and how to integrate grid-connected converters on a large scale into the power grid to verify their true supporting role in the actual power grid.

[0052] In view of this, this application provides a control method for a test system for grid-connected converters connected to complex power systems, aiming to solve at least one of the above-mentioned technical problems.

[0053] Please see Figure 1 As shown, Figure 1 This is a structural block diagram of a test system for connecting a grid-type converter to a complex power system, provided in an embodiment of this application.

[0054] This application provides a test system for grid-connected converters connected to complex power systems, applied to the testing process of grid-connected converters under test in complex power systems. The test system includes:

[0055] The real-time simulation module is used to construct interconnected pre-set complex power system models and semi-physical grid-type converter primary system models, and to output modulation signals based on the pre-set complex power system models, semi-physical AC signals, and physical AC signals.

[0056] A semi-physical grid-type converter controller is connected to a semi-physical grid-type converter primary system model to form a semi-physical grid-type converter. The semi-physical grid-type converter controller is used to control the semi-physical grid-type converter primary system model so that the semi-physical grid-type converter primary system model outputs a semi-physical AC signal to a preset complex power system model.

[0057] A physical grid-type converter is connected to a pre-set complex power system model. The physical grid-type converter is used to output physical AC signals from the AC port to the pre-set complex power system model.

[0058] The controllable converter is connected to a preset complex power system model and a physical grid-type converter respectively. The controllable converter is used to modulate based on the modulation signal to output the first electrical signal to the AC port of the physical grid-type converter.

[0059] Among them, the semi-physical grid converter and the physical grid converter together constitute the grid converter under test.

[0060] Please see Figure 2 As shown, Figure 2 This is a structural block diagram of a test system for connecting a grid-type converter to a complex power system, as provided in an embodiment of this application.

[0061] The real-time simulation module is connected to the semi-physical grid-type converter controller, the AC port of the physical grid-type converter, and the controllable converter. Based on the acquired semi-physical and physical AC signals, and combined with a pre-constructed complex power system model, the real-time simulation module outputs a modulation signal to the controllable converter. The modulation signal simulates the dynamic behavior and response characteristics of the grid connection point in a real power system, allowing the controllable converter to modulate to simulate the grid conditions corresponding to the modulation signal. It should be noted that the physical AC signal includes at least one of the voltage and current at the AC port of the physical grid-type converter, and the semi-physical AC signal includes at least one of the voltage and current at the AC port of the semi-physical grid-type converter. The real-time simulation module can acquire the voltage and current at the AC port of the physical grid-type converter using voltage and current sensors.

[0062] In some embodiments, the real-time simulation module includes: a real-time simulation interface board, through which the semi-physical grid-type converter controller is connected to the primary system model of the semi-physical grid-type converter, and the physical grid-type converter is connected to a preset complex power system model through the real-time simulation interface board. For example, the real-time simulation module may include a simulation server, a real-time simulator, and the real-time simulation interface board. The simulation server is used to install and run real-time simulation software, and through the real-time simulation software, to construct a preset complex power system model containing a large-scale new energy power generation system and a large-scale grid-type converter, and to download the compiled model to the real-time simulator. Simultaneously, the primary system model of the semi-physical grid-type converter is also constructed based on the simulation server, and the compiled model is downloaded to the real-time simulator. The real-time simulation interface board is used to implement the real-time interface between the real-time simulator and the semi-physical grid-type converter controller module, the controllable converter, and the physical grid-type converter. The real-time simulator is used to perform real-time calculations on the preset complex power system model to simulate the transient and steady-state characteristics of a large-capacity complex power system. Furthermore, the real-time simulator, through a real-time simulation interface board, can receive switching commands and trigger pulses from the semi-physical grid-type converter controller module, the DC voltage of the controllable converter, and the AC port voltage and current signals of the physical grid-type converter in real time. It also provides the semi-physical grid-type converter controller module with voltage, current, and switching status signals for the semi-physical grid-type converter. Additionally, the real-time simulator can perform real-time calculations based on preset complex power system models, semi-physical AC signals, and physical AC signals, thereby providing modulation signals to the controllable converter in real time.

[0063] The pre-set complex power system model can include large-scale new energy power generation, different types of loads, large-capacity synchronous generator sets, grid-connected converters, transformers, transmission lines, collector lines, faulty components, etc. The architecture, parameters, and grid connection points of the grid-connected converters in the pre-set complex power system model are configured according to testing requirements. The system capacity of large-capacity complex power systems can reach the GW level, specifically simulated based on the actual power grid structure. The semi-physical grid-connected converter primary system model refers to the circuit components of the grid-connected converter built in the simulation environment, including DC-to-AC conversion, inverter configuration, and grid connection methods. The constructed semi-physical grid-connected converter primary system model can be used to simulate the physical behavior and electrical characteristics of the grid-connected converter. It should be noted that the semi-physical grid-connected converter primary system model does not include the controller.

[0064] In this application, the real-time simulation module can construct a large-capacity complex power system model containing large-scale new energy power generation systems through a hybrid modeling approach with varying step sizes. This simulates the transient steady-state characteristics of a large power grid with large-scale new energy grid integration, enabling real-time interfacing between the large-capacity complex power system and large-scale semi-physical and physical grid-connected converters. This provides a system grid connection interface for testing the integration of semi-physical and physical grid-connected converters into the large-capacity complex power system. Furthermore, both the semi-physical and physical grid-connected converters connect to the grid connection point provided by the preset complex power system model via the real-time simulation interface board, thereby transmitting signals. Specifically, the semi-physical AC signal and the physical AC signal are transmitted to the preset complex power system model through the grid connection point, and the modulated signal is output through the grid connection point.

[0065] Please see Figure 2 and Figure 3 As shown, Figure 3 This is a simulation diagram of a semi-physical network converter provided for an embodiment of this application.

[0066] The semi-physical network converter controller connects to the primary system model of the semi-physical network converter in the real-time simulator via a real-time simulation interface board, and the two together form the semi-physical network converter. The overall structure of the semi-physical network converter is as follows: Figure 3As shown, a semi-physical grid-type converter controller enables real-time control of the semi-physical grid-type converter. An exemplary process by which the semi-physical grid-type converter controller controls the primary system model of the semi-physical grid-type converter to output a semi-physical AC signal to a preset complex power system model is as follows: The semi-physical grid-type converter controller can send switching commands to the primary system model of the semi-physical grid-type converter via a real-time simulation interface board to control the switching state of the primary system model. When the primary system model is on, the semi-physical grid-type converter controller can send trigger pulses to the primary system model via the real-time simulation interface board. These trigger pulses control the switching state of the power semiconductor devices in the primary system model, thereby achieving energy conversion and regulation, and ultimately enabling the primary system model of the semi-physical grid-type converter to generate a semi-physical AC signal for the preset complex power system model. It should be noted that the real-time simulation module will also feed back the voltage, current and switching status signals of the primary system model of the semi-physical grid converter to the semi-physical grid converter controller through the real-time simulation interface board, so that the semi-physical grid converter controller can make real-time adjustments based on the current voltage, current and switching status.

[0067] The physical grid-connected converter is connected to a pre-set complex power system model via a real-time simulation interface board. The physical AC signals from the converter's AC ports are then transmitted to the model through this interface board. The process of the real-time simulator acquiring these signals involves the converter first converting its port voltage and current signals into secondary signals using voltage and current sensors, respectively. These secondary signals are then fed into the real-time simulator via the interface board, thus achieving closed-loop connection of the converter to the pre-set complex power system model. It should be noted that the physical grid-connected converter is a physical converter connected to the test system.

[0068] The controllable converter transmits DC voltage to a preset complex power system model via a real-time simulation interface board. Conversely, the preset complex power system model transmits a modulation signal to the controllable converter via the same interface board. This allows the controllable converter to modulate the signal and output a first electrical signal to the AC port of the physical grid-type converter. In this application, the controllable converter serves as the full-power physical interface between the physical grid-type converter and the real-time simulation module, providing AC voltage to the physical grid-type converter.

[0069] The controllable converter comprises a rectifier converter and an inverter converter. Both the rectifier converter and the inverter converter enable bidirectional power flow. The rectifier converter provides DC voltage to the inverter converter, which receives a modulation signal from a real-time simulator via a high-speed communication protocol. The inverter converter converts the modulation signal into an actual AC voltage and provides it to the AC port of the physical grid-type converter. In other words, the inverter converter simulates the voltage and frequency fluctuations of the real power grid based on the modulation signal and outputs it to the AC port of the physical grid-type converter. Thus, the physical grid-type converter actively follows the first electrical signal output by the controllable converter. This first electrical signal can be at least one of the AC voltage or AC current on the AC side of the controllable converter.

[0070] In this application, a semi-physical grid-type converter and a physical grid-type converter together constitute the grid-type converter under test (DUT). That is, the total capacity of the semi-physical grid-type converter and the physical grid-type converter can meet the capacity requirements of the pre-designed complex power system. This allows the semi-physical grid-type converter and the physical grid-type converter to jointly support the capacity requirements of the pre-designed complex power system, ensuring that the grid-type converter can effectively support the power grid, thereby enabling performance testing of the physical grid-type converter under test applied in complex power systems.

[0071] Through the above technical solutions, this application provides a test system for connecting a grid-type converter to a complex power system. This test system includes a real-time simulation module, a semi-physical grid-type converter controller, a physical grid-type converter, and a controllable converter. The real-time simulation module is used to construct a preset complex power system model and a primary system model of the semi-physical grid-type converter. The preset complex power system model allows the test system to simulate the grid environment of a real complex power system, thus facilitating the testing of the grid-type converter under test under complex power system conditions. Furthermore, by combining the semi-physical grid-type converter controller with the primary system model to form a semi-physical grid-type converter, and then combining the semi-physical and physical grid-type converters to constitute the grid-type converter under test, large-scale hybrid simulation of the semi-physical and physical grid-type converters is achieved. This improves the convenience of building a test system for simulating large-capacity complex power systems, thereby providing a foundation for conducting research on the complete testing of the grid-type converter's network characteristics and system-level characteristic testing.

[0072] In some embodiments, the real-time simulation module is used to output a modulated signal based on a preset complex power system model, a semi-physical AC signal, and a physical AC signal, including:

[0073] Construct a pre-defined complex power system model, which includes complex power models under various pre-defined operating conditions;

[0074] Based on the complex power model, semi-physical AC signal, and physical AC signal under each preset operating state, the modulated signal corresponding to the complex power model under each preset operating state is output.

[0075] It's important to understand that the real-time simulation module can be used to build and simulate pre-defined complex power system models. By modeling these pre-defined complex power system models, the dynamic behavior and response characteristics of grid-connected points in real complex power systems can be simulated. These pre-defined complex power system models include complex power models under various pre-defined operating states. These models can include switching on renewable energy sources, adjusting renewable energy wind speed / solar intensity, switching on loads, adjusting load sizes, switching on and off synchronous generators, adjusting synchronous generator output, switching on and off transformers, switching on and off AC lines, adjusting line parameters, switching on and off faults, and switching on and off grid-connected converters. Faults include three-phase faults, two-phase faults, phase-to-phase faults, and single-phase faults. Fault types include metallic faults and non-metallic faults. Fault points can be located anywhere within the complex power system. Specifically, the complex power models under various pre-defined operating states can be obtained by changing or adjusting the model structure or parameters, or by adding disturbances, based on the built complex power model. It should be noted that the pre-defined complex power model can be a single power model, and consequently, the complex power models under various pre-defined operating states can be obtained by changing or adjusting the model structure or parameters, or by adding disturbances, based on this single power model.

[0076] In some embodiments, the real-time simulation module can build a corresponding preset complex power system model according to the actual power grid conditions. Then, the real-time simulation module collects semi-physical AC signals and physical AC signals in real time. Based on the real-time collected semi-physical AC signals, physical AC signals, and the built preset complex power system model, the real-time simulation module updates the output modulation signal to the controllable converter in real time. Understandably, when the preset complex power system model changes—that is, when the preset complex power system model changes between the complex power models under various preset operating states—the real-time simulation module will output a new modulation signal for modulation. This causes the controllable converter to output a first electrical signal to the AC port of the physical grid-type converter. The AC port of the physical grid-type converter will generate a new physical AC signal, which will be input to the real-time simulation module. The real-time simulation module will feed back the new physical AC signal to the power grid system to determine the physical AC signal of the physical grid-type converter under fluctuations, thereby achieving simulation testing of the physical grid-type converter. Furthermore, the real-time simulation module will generate a new modulation signal based on the current preset complex power system model, the semi-physical AC signal, and the physical AC signal, and transmit it to the controllable converter. It should be noted that in this application, the semi-physical grid-type converter mainly relies on the semi-physical grid-type converter controller for modulation to generate the semi-physical AC signal.

[0077] In other embodiments, the real-time simulation module, based on a pre-built complex power system model, can provide an initial reference voltage at the grid connection point simulating a real power system. The real-time simulation module can then determine the modulation signal in real time based on the unlocking total signal of the controllable converter, the DC voltage of the controllable converter, and the initial reference voltage. Specifically, firstly, the reference voltage at the grid connection point is determined in real time based on the unlocking total signal and the initial reference voltage. For example, when the unlocking total signal is valid, the real-time reference voltage at the grid connection point is determined based on the product of the real-time data of the initial reference voltage and a preset start-stop coefficient. At this time, the preset start-stop coefficient increases from a first threshold to a second threshold based on a first preset rate, causing the real-time value of the reference voltage at the grid connection point to increase based on the increase of the preset start-stop coefficient until it equals the initial reference voltage at the grid connection point. The first threshold can be greater than or equal to 0, the second threshold is 1, and the first threshold is less than the second threshold. The first preset rate can be a constant rate, a uniform acceleration rate, or a variable rate, set according to the requirements of the actual implementation scheme. Furthermore, when the unlock signal is invalid, the real-time reference voltage of the grid connection point is determined based on the product of the real-time data of the initial reference voltage and the preset start-stop coefficient. At this time, the preset start-stop coefficient decreases from the second threshold to the first threshold at a second preset rate, causing the real-time value of the reference voltage at the grid connection point to decrease as the preset start-stop coefficient decreases. The second preset rate can be the same magnitude as the first preset rate but in the opposite direction, or it can be different from the first preset rate, depending on the requirements of the actual implementation scheme. Then, based on the reference voltage and the DC voltage, the modulation signal of the controllable power module is determined in real time. For example, the modulation signal = half of the reference voltage at the grid connection point / half of the DC voltage.

[0078] It should be noted that changes to the pre-constructed complex power system model, or changes to the semi-physical or physical AC signal, will result in corresponding changes to the initial reference voltage. Furthermore, the overall unlock signal is obtained by performing a logical operation on the unlock signals of the controllable converters connected to the same grid connection point. The DC voltage of the controllable converter is obtained by averaging the DC bus voltages of the controllable converters connected to the same grid connection point. It should also be noted that, based on the modulation signal, the controller corresponding to the controllable converter outputs a trigger pulse to the inverter in the controllable converter, causing the controllable converter to modulate. The unlock signal includes valid and invalid signals; a valid signal indicates that the controllable converter is operating, and an invalid signal indicates that the controllable converter is not operating. The overall unlock signal is valid only when all unlock signals of the controllable converters connected to the same grid connection point are valid. The overall unlock signal is invalid when the unlock signal of any one of the controllable converters connected to the same grid connection point is invalid.

[0079] Understandably, the real-time simulation module can simulate complex power models under various operating conditions and provide different voltage conditions in a timely manner to adapt to various power system scenarios. This allows it to cover a wide range of operating conditions for grid-connected converters, enabling modulation of controllable converters. This, in turn, helps to conduct complete grid-connected converter characteristic tests and system-level characteristic tests, thereby providing an in-depth evaluation of the grid-connected converter's grid performance.

[0080] Please see Figure 2 and Figure 4 As shown, Figure 4 A schematic diagram of the physical grid-type converter interface model provided in the embodiments of this application.

[0081] In some embodiments, the real-time simulation module is also used to construct a physical grid-type converter interface model, which is connected to a preset complex power system model, the AC port of the physical grid-type converter, and the controllable converter, respectively.

[0082] The physical grid-type converter interface model is used to process the physical AC signal using the first aggregation method and output it to the preset complex power system model; and the physical grid-type converter interface model is used to output the modulated signal to the controllable converter.

[0083] The physical grid-connected converter interface model is set between the preset complex power system model and the AC port of the physical grid-connected converter. The physical AC signal passes through the real-time simulation interface board, and then is processed by the physical grid-connected converter interface model before being output to the preset complex power system model. Furthermore, the modulated signal output from the preset complex power system model passes through the physical grid-connected converter interface model and then is transmitted to the controllable converter via the real-time simulation interface board.

[0084] Understandably, physical grid-connected converters are connected to the physical grid-connected converter interface model in the real-time simulator through a real-time simulation interface board. The physical grid-connected converter interface model is based on the first aggregation method, which can realize the large-scale access of physical grid-connected converters to large-capacity complex power systems, and improve the convenience of building a test system for simulating large-capacity complex power systems.

[0085] like Figure 4 As shown, in some embodiments, the physical AC signal includes the physical AC current signal;

[0086] The physical grid-type converter interface model includes:

[0087] The aggregation unit is connected to the AC port of the preset complex power system model and the physical grid-type converter, respectively. The aggregation unit is used to process the physical AC current signal using the first aggregation method and output it to the preset complex power system model.

[0088] It should be understood that the aggregation unit enables the physical AC current signal to pass through the real-time simulation interface board, and then, after processing by the aggregation unit using a first aggregation method, is output to the preset complex power system model. It should be noted that, in this application, the first aggregation method refers to multiplying the physical AC current signal by a preset first factor. This ensures that the capacity of the physical grid-connected converter remains constant while the power is aggregated and output to the preset complex power system model; that is, the voltage level remains constant in the physical grid-connected converter interface model, and the current is multiplied by the preset first factor to achieve the preset first factor power aggregation. For example, the aggregation unit can use analog multipliers, operational amplifiers, multiplier circuits, etc., to implement the preset first factor multiplication processing of the physical AC current signal.

[0089] Understandably, aggregation units enable large-scale physical grid-type converters to be connected to large-capacity, complex power systems, thereby reducing the complexity of the testing system.

[0090] Please see Figure 4 As shown, the physical grid-type converter interface model also includes:

[0091] The current source is connected to the AC port of the physical grid converter and the aggregation unit respectively. The current source is used to convert the physical AC signal collected from the AC port of the physical grid converter into a current signal. That is, the physical AC signal collected by the sensor from the AC port of the physical grid converter is sent to the current source, so that the current source performs current conversion and outputs the converted current to the aggregation unit for processing by the first aggregation method.

[0092] The filtering unit is connected to the grid connection point and aggregation unit of the preset complex power system model, respectively. The physical AC current signal is processed by the aggregation unit through a first aggregation method, and then filtered by the filtering unit before being sent to the grid connection point of the preset complex power system model. It is understood that the filtering unit can effectively suppress high-frequency noise and interference signals, and can smooth fluctuations and spikes in the signal, providing a more stable physical AC current signal. For example, the filtering unit may include inductor L1, inductor L2, and capacitor C. One end of capacitor C is grounded, and the other end of capacitor C is connected to one end of inductor L1 and one end of inductor L2. The other end of inductor L1 is connected to the grid connection point of the preset complex power system model, and the other end of inductor L2 is connected to the output terminal of the aggregation unit.

[0093] Understandably, the interface model of a physical grid-connected converter can include current sources, aggregation units, and filtering units. That is, the physical AC current signal sequentially passes through the current source, aggregation unit, and filtering unit before being output to a pre-defined complex power system model. While reducing the complexity of the test system by enabling large-scale physical grid-connected converters to connect to large-capacity complex power systems, this also reduces interference in the signal to provide a more stable physical AC current signal, thereby ensuring the stability of the test system.

[0094] It should also be noted that the modulation signal output from the physical grid-connected converter interface model is located between the filter unit and the grid connection point. This means that the modulation signal output from the pre-set complex power system model is transmitted to the controllable converter via the real-time simulation interface board without processing in the physical grid-connected converter interface model. Please refer to [link / reference]. Figure 4 As shown, the U-shaped connection point ref As the modulation signal of the controllable converter, it is at the same voltage level as the port voltage of the physical grid-type converter. The port current i of the physical grid-type converter is multiplied by the aggregation factor K and then fed back to the large-capacity complex power system.

[0095] In some embodiments, the primary system model of the semi-physical grid converter is also used to process the semi-physical AC signal using a second aggregation method and output it to a preset complex power system model.

[0096] It's important to understand that the primary system model of a semi-physical network converter processes the semi-physical AC signal using a second aggregation method. This means that the voltage and current in the semi-physical AC signal of a single semi-physical network converter are increased by a factor of √N, thereby increasing the power by a factor of N. This allows one semi-physical network converter to be equivalent to the power of multiple semi-physical network converters. The value of N can be set according to the requirements of the actual implementation scheme.

[0097] It's important to understand that semi-physical AC signals include both semi-physical AC voltage and current signals. The primary system model of a semi-physical grid-type converter processes these signals using a second aggregation method: multiplying both the semi-physical AC voltage and current signals before outputting them to a pre-defined complex power system model. As we know, multiplying both the semi-physical AC voltage and current signals achieves a pre-defined second-multiplier power aggregation. For example, the second aggregation method boosts both the semi-physical AC voltage and current signals... This allows for N times power aggregation. It should be noted that the preset second multiplier can be the same as or different from the preset first multiplier.

[0098] For example, processing the semi-physical AC signal in the primary system model of a semi-physical network converter using a second aggregation method can be achieved as follows: Based on the principle that the input impedance of the transformer valve-side converter remains unchanged, the system parameters of the primary system are not altered, and the equivalent impedance of the converter remains constant before and after aggregation. By changing the transformer turns ratio in the primary system model to increase the secondary voltage, the primary input impedance is reduced to 1 / N of the impedance before aggregation, resulting in a √N-fold increase in the secondary voltage. Consequently, the output power of the primary system model increases by a factor of N. Since the equivalent impedance of the converter remains unchanged before and after aggregation, the voltage and current for both DC and AC operation in the primary system model increase by a factor of N. Therefore, the number of series and parallel connections in the primary system model increases by a factor of N.

[0099] Understandably, the semi-physical grid-connected converter primary system model is processed using a second aggregation method, further reducing the scale of physical grid-connected converters connected to the test system, thereby further reducing the complexity of the test system. Furthermore, in the test system, both semi-physical grid-connected and physical grid-connected converters are connected to a large-capacity complex power model through power aggregation, thus enabling large-capacity access of grid-connected converters to large and complex power systems. This satisfies the testing requirements of complex power grid systems while reducing the scale of physical grid-connected converters connected to the test system, improving the ease of setting up a test system simulating large-capacity complex power systems connected to physical grid-connected converters.

[0100] In some embodiments, the test system further includes a coordination controller connected to both the semi-physical grid-type converter controller and the physical grid-type converter. The coordination controller determines the power commands corresponding to the semi-physical grid-type converter and the physical grid-type converter based on their operating states, the operating states of the physical grid-type converter, and a preset power command, and sends the power commands to the corresponding semi-physical grid-type converter controller and the physical grid-type converter. It should be noted that the operating states of the semi-physical grid-type converter and the physical grid-type converter refer to whether the converter is running and the current and power levels of the converter. The preset power command can be a total power set according to the real-time demand of the power grid. The sum of the power of all semi-physical grid-type converters after the second aggregation method and the power of all physical grid-type converters after the first aggregation method is equal to the total power of the preset power command.

[0101] like Figure 2As shown, it is important to understand that the coordination controller is used to achieve coordinated control of the semi-physical network converter and the physical network converter. The controllers of both the semi-physical network converter and the physical network converter are directly connected to the coordination controller. Based on the operating status and preset power commands of the semi-physical network converter and the physical network converter, the coordination controller calculates the real-time power commands of these converters and transmits them to their respective controllers, thereby controlling the output power of the semi-physical network converter and the physical network converter.

[0102] For example, the process by which the coordination controller calculates the real-time power commands for the semi-physical grid converter and the physical grid converter based on their operating states and preset power commands is as follows:

[0103] When both the semi-physical grid converter and the physical grid converter are in startup mode, and their rated capacity and operating status are the same, the power aggregation equivalent multiple for the semi-physical grid converter is m (the preset first multiple is m), and the power aggregation equivalent multiple for the physical grid converter is n (the preset second multiple is n). The active power command in the preset power command is Pref. At this time, the real-time active power command for both the semi-physical grid converter and the physical grid converter calculated by the coordination controller is Pref_PCS = Pref / (m+n). The reactive power command allocation method is the same as the active power command allocation. The reactive power command in the preset power command is Qref, meaning the real-time reactive power command for both the semi-physical grid converter and the physical grid converter calculated by the coordination controller is Qref_PCS = Qref / (m+n). It should be noted that the preset power command includes active power command and reactive power command. Furthermore, the power commands corresponding to semi-physical grid-type converters and physical grid-type converters respectively include real-time active power command and real-time reactive power command. It should also be noted that the rated capacity of semi-physical grid-type converters and physical grid-type converters refers to the rated capacity before the first aggregation method and the second aggregation method are applied.

[0104] When the rated capacities of semi-physical grid converters and physical grid converters differ, the power command is allocated among the different grid converter types according to the ratio of their rated capacities. For example, the power aggregation equivalent multiple of a semi-physical grid converter is m, and its rated capacity is Pn1; the power aggregation equivalent multiple of a physical grid converter is n, and its rated capacity is Pn2. When the active power command in the preset power command is Pref, the real-time active power command calculated by the coordination controller for the semi-physical grid converter is: Pref_PCS1 = Pref*Pn1 / (m*Pn1+n*Pn2), and the real-time active power command for the physical grid converter is: Pref_PCS2 = Pref*Pn2 / (m*Pn1+n*Pn2). Furthermore, when the reactive power command in the preset power command is Qref, the real-time reactive power command of the semi-physical grid converter calculated by the coordinating controller is: Qref_PCS1=Qref*Pn1 / (m*Pn1+n*Pn2), and the real-time active power command of the physical grid converter is Qref_PCS2=Qref*Pn2 / (m*Pn1+n*Pn2).

[0105] It should be noted that when the power aggregation multiple of semi-physical grid-connected converters and physical grid-connected converters connected to a complex power system is 1, it is equivalent to the semi-physical and physical grid-connected converters being directly connected to the complex power system without power aggregation processing. In this case, since the capacity of a single semi-physical or physical grid-connected converter is relatively small, it is usually necessary to synchronously adjust the equivalent capacity and system parameters of the complex power system to match the scale of the complex power system with the grid-connected converters.

[0106] Understandably, the test system can include a coordination controller. When only one coordination controller is included, the controllers of all semi-physical grid converters and physical grid converters are directly connected to this coordination controller. Furthermore, the coordination controller can calculate the real-time power command for each semi-physical grid converter and physical grid converter based on their operating status and the system power command, and transmit this command to their respective controllers, thereby achieving coordinated control of the semi-physical grid converters and physical grid converters.

[0107] However, to effectively support complex power grid systems, grid-connected converters require large-scale testing within a testing system. Therefore, the testing system can include at least one semi-physical grid-connected converter and at least one physical grid-connected converter. Each semi-physical grid-connected converter and physical grid-connected converter is then connected to a large-capacity complex power system via power aggregation, thus enabling multi-node access of grid-connected converters to a large-capacity complex power system. It should be noted that each semi-physical grid-connected converter consists of one semi-physical grid-connected converter controller and one semi-physical grid-connected converter primary system model. That is, multiple semi-physical grid-connected converters consist of multiple semi-physical grid-connected converter controllers and corresponding multiple semi-physical grid-connected converter primary system models. It should also be noted that each semi-physical grid-connected converter and each physical grid-connected converter can be connected to different grid connection points, or at least one semi-physical grid-connected converter can be connected to the same grid connection point, or at least one semi-physical grid-connected converter and at least one physical grid-connected converter can be connected to the same grid connection point, depending on the actual scheme requirements. It should also be noted that the amplification factor after aggregation processing for each semi-physical grid-connected converter and each physical grid-connected converter can be different; that is, different semi-physical grid-connected converters can have different power boost factors, and different physical grid-connected converters can also have different power boost factors.

[0108] For example, when the test system includes at least one semi-physical grid converter and at least one physical grid converter, the process by which the coordination controller calculates the real-time power commands of the semi-physical grid converter and the physical grid converter based on their operating states and preset power commands is as follows:

[0109] The test system includes two semi-physical grid converters and two physical grid converters as an example. With both the semi-physical grid converters and physical grid converters in startup mode, and assuming the rated capacity and operating status of each converter are identical, the power aggregation equivalent multiples for the two semi-physical grid converters are m1 and m2, and the power aggregation equivalent multiples for the two physical grid converters are n1 and n2. The preset power command includes the active power command Pref. The real-time active power command for both converters, calculated by the coordinating controller, is Pref_PCS = Pref / (m1 + m2 + n1 + n2). The reactive power command allocation method is the same as the active power command allocation. The reactive power command in the preset power command is Qref, meaning the real-time reactive power command for both semi-physical grid-type and physical grid-type converters, calculated by the coordinating controller, is Qref_PCS = Qref / (m1+m2+n1+n2). Therefore, it can be seen that, assuming the rated capacity and operating status of both semi-physical grid-type and physical grid-type converters are the same, the real-time power command for each converter is obtained by dividing the preset power command by the sum of the equivalent multiples of all converters.

[0110] When the rated capacity of each semi-physical grid converter and each physical grid converter differs, the power command among different grid converters is allocated proportionally according to their rated capacity. For example, the power aggregation equivalent multiple of the first semi-physical grid converter is m1, and its rated capacity is Pn1; the power aggregation equivalent multiple of the second semi-physical grid converter is m2, and its rated capacity is Pn2; the power aggregation equivalent multiple of the first physical grid converter is n1, and its rated capacity is Pn3; and the power aggregation equivalent multiple of the second physical grid converter is n2, and its rated capacity is Pn4. When the active power command in the preset power command is Pref, the real-time active power command of the first semi-physical grid converter calculated by the coordinating controller is Pref_PCS1 = Pref*Pn1 / (m1*Pn1+m2*Pn2+n1*Pn3+n2*Pn4), and the real-time active power command of the second semi-physical grid converter is Pref_PCS2 = Pref*Pn2 / (m1*Pn1+m2*Pn4). The real-time active power command for the first physical grid-type converter is Pref_PCS3 = Pref*Pn3 / (m1*Pn1+m2*Pn2+n1*Pn3+n2*Pn4), and the real-time active power command for the second physical grid-type converter is Pref_PCS4 = Pref*Pn4 / (m1*Pn1+m2*Pn2+n1*Pn3+n2*Pn4). Furthermore, when the reactive power command in the preset power command is Qref, the real-time reactive power command of the first semi-physical grid converter calculated by the coordinating controller is Qref_PCS1 = Qref*Pn1 / (m1*Pn1+m2*Pn2+n1*Pn3+n2*Pn4), and the real-time reactive power command of the second semi-physical grid converter is Qref_PCS2 = Qref*Pn2 / (m1*Pn1+m2*Pn4). The real-time active power command for the first physical grid-connected converter is Qref_PCS3 = Qref*Pn3 / (m1*Pn1+m2*Pn2+n1*Pn3+n2*Pn4), and the real-time active power command for the fourth physical grid-connected converter is Qref_PCS4 = Qref*Pn4 / (m1*Pn1+m2*Pn2+n1*Pn3+n2*Pn4). Therefore, it can be understood that when the rated capacity of each semi-physical grid converter and each physical grid converter is different, the real-time power command for each semi-physical grid converter and physical grid converter is obtained by multiplying the preset power command by the rated capacity of the corresponding converter, and then dividing by the sum of the products of the equivalent multiples of all semi-physical grid converters and physical grid converters and their corresponding rated capacities. The preset power command includes both active power command and reactive power command.

[0111] It's also important to understand that each grid-connected point in the test system corresponds to a modulation signal; that is, each grid-connected point corresponds to at least one controllable converter and one physical grid-connected converter interface model. Furthermore, any grid-connected point in the test system, after passing through the physical grid-connected converter interface model, outputs a modulation signal to the corresponding controllable converter via the real-time simulation interface board. The controllable converter modulates based on the modulation signal to output a first electrical signal to the AC ports of each physical grid-connected converter connected to that grid-connected point. Additionally, that grid-connected point collects the semi-physical AC signals from the semi-physical grid-connected converters connected to it, as well as the physical AC signals from the physical grid-connected converters, to generate a new modulation signal.

[0112] Please see Figure 5 As shown, Figure 5 A simplified structural diagram illustrating the connection of multiple semi-physical and physical grid-type converters to a complex power system, as provided in the embodiments of this application.

[0113] Understandably, connecting multiple grid-connected converters, combined with power aggregation methods, makes it possible to conduct simulations of complex power systems with GW-level grid-connected converters. For example... Figure 5 As shown, taking a 1GW grid-connected energy storage system as an example, assuming that the 1GW grid-connected energy storage system consists of 5 energy storage stations, each with a capacity of 200MW, then 3 semi-physical grid-connected energy storage converters with a single rated power of 1.25MW and 2 full-power grid-connected energy storage converters with a single rated power of 1.25MW can be used to connect to the complex power system through 160 times power aggregation.

[0114] In some embodiments, the coordination controller includes a main coordination controller and a plurality of sub-coordination controllers, the main coordination controller being connected to each sub-coordination controller, and any one of the sub-coordination controllers being connected to a semi-physical grid converter controller and / or a physical grid converter.

[0115] Figure 5 In the diagram, semi-physical and physical grid-connected converters are connected to a pre-defined complex power model via power aggregation. To ensure coordinated power control of multiple semi-physical and physical grid-connected converters, the coordination controller is divided into two types: a master coordination controller and sub-coordination controllers. The controllers of the semi-physical and physical grid-connected converters are first connected to the sub-coordination controllers, and then connected to the master coordination controller through the sub-coordination controllers. One master coordination controller can connect to multiple sub-coordination controllers, and any sub-coordination controller can connect to at least one semi-physical grid-connected converter and / or a physical grid-connected converter. It is important to understand that the sub-coordination controllers are essentially connected to the controllers of the semi-physical grid-connected converters and the physical grid-connected converters.

[0116] In other words, any sub-coordination controller can connect to at least one semi-physical grid-type converter, or at least one physical grid-type converter. Furthermore, any sub-coordination controller can also connect to both at least one semi-physical grid-type converter and at least one physical grid-type converter. Moreover, in some examples, the sub-coordination controllers can be divided into a first group and a second group. Each sub-coordination controller in the first group is connected to at least one semi-physical grid-type converter, and each sub-coordination controller in the second group is connected to at least one physical grid-type converter. In other examples, the sub-coordination controllers can be a third group, and each sub-coordination controller in the third group can connect to both at least one semi-physical grid-type converter and at least one physical grid-type converter.

[0117] It should be understood that, in some embodiments, the sub-coordination controller can be further divided into a first group of sub-coordination controllers and a third group of sub-coordination controllers. The connection method of the first group of sub-coordination controllers and the third group of sub-coordination controllers can be referred to the description in the above embodiments, and will not be repeated here. In other embodiments, the sub-coordination controller can be further divided into a first group of sub-coordination controllers, a second group of sub-coordination controllers, and a third group of sub-coordination controllers. The connection method of the first group of sub-coordination controllers, the second group of sub-coordination controllers, and the third group of sub-coordination controllers can be referred to the description in the above embodiments, and will not be repeated here. In still other embodiments, the sub-coordination controller can be further divided into a first group of sub-coordination controllers, a second group of sub-coordination controllers, and a third group of sub-coordination controllers. The connection method of the first group of sub-coordination controllers, the second group of sub-coordination controllers, and the third group of sub-coordination controllers can be referred to the description in the above embodiments, and will not be repeated here.

[0118] It is also necessary to understand that the process by which the main coordinating controller distributes power to each semi-physical grid converter and each physical grid converter through multiple sub-coordinating controllers is as follows:

[0119] First, the main coordinating controller distributes the preset power command to each sub-coordinating controller based on the preset power command and the proportion of the total power of the grid-type converters connected to each sub-coordinating controller to the total power corresponding to the preset power command in the main coordinating controller. The grid-type converter connected to each sub-coordinating controller can be a semi-physical grid-type converter, a physical grid-type converter, or a combination of both.

[0120] Then, each sub-coordination controller, based on the operating status of the grid-connected converters and the power command allocated by the main coordinating controller, determines the corresponding power command for each connected grid-connected converter and sends the power command to the controller of the corresponding grid-connected converter. The specific process by which each sub-coordination controller calculates the corresponding power command for each connected grid-connected converter based on the operating status of the connected grid-connected converters and the power command allocated by the main coordinating controller can be referenced from the process described above for calculating the real-time power commands of semi-physical and physical grid-connected converters. It can be seen that, when the rated capacity and operating status of the grid-connected converters are the same, the real-time power command for each grid-connected converter is obtained by dividing the allocated power command obtained by the sub-coordination controller by the sum of the equivalent multiples of all connected grid-connected converters. When the rated capacity of each grid-connected converter is different, the real-time power command for each grid-connected converter is obtained by multiplying the power allocation command obtained by the sub-coordination controller by the rated capacity of the corresponding converter, and then dividing by the sum of the products of the equivalent multiples of all connected grid-connected converters and their corresponding rated capacities. The power allocation command obtained by the sub-coordination controller includes both active power allocation commands and reactive power allocation commands.

[0121] Understandably, the architecture of a main coordinating controller and multiple sub-coordinating controllers can significantly improve the stability, efficiency, and reliability of power systems, while providing flexible control and management capabilities to adapt to the complex needs of power systems.

[0122] In some embodiments, the testing system further includes:

[0123] A DC power supply is connected to the DC side of the physical grid converter. The DC power supply is used to provide a second electrical signal to the DC side of the physical grid converter.

[0124] Understandably, a DC power supply is used to provide DC voltage for a physical grid-connected converter. The DC power supply can be a power electronic converter or a battery system. When the DC power supply is a power electronic converter, it can simulate the output characteristics of a photovoltaic panel or energy storage battery. The second electrical signal can include at least one of DC voltage and DC current.

[0125] Please see Figure 6 As shown, Figure 6 This is a schematic diagram of a control method for a test system for connecting a grid-type converter to a complex power system, provided in an embodiment of this application.

[0126] This application also provides a control method for a test system of a grid-connected converter connected to a complex power system. The control method includes:

[0127] Start the real-time simulation module. The real-time simulation module is used to build an interconnected pre-set complex power system model and a semi-physical grid-type converter primary system model, and output a modulation signal based on the pre-set complex power system model, the semi-physical AC signal and the physical AC signal.

[0128] Start the semi-physical grid converter controller. The semi-physical grid converter controller is used to control the primary system model of the semi-physical grid converter so that the primary system model of the semi-physical grid converter outputs a semi-physical AC signal to the preset complex power system model.

[0129] Start the controllable converter, which is used to modulate based on the modulation signal to output the first electrical signal to the AC port of the physical grid converter;

[0130] Start the physical grid-type converter. The physical grid-type converter is used to output the physical AC signal from the AC port to the preset complex power system model.

[0131] The preset complex power system model includes complex power models under various preset operating states; the real-time simulation module outputs the modulation signal corresponding to the complex power model under each preset operating state based on the complex power model, semi-physical AC signal, and physical AC signal.

[0132] It is important to understand that the control method of a test system based on grid-connected converters in complex power systems can be specifically described as follows:

[0133] S1: Start the real-time simulation module to provide the converter voltage, current, and switching status signals to the semi-physical network converter controller, and to provide the modulated voltage signal to the controllable converter;

[0134] S2: Start the controllable converter and provide AC voltage to the physical grid-type converter based on the modulation signal.

[0135] S3: Start the physical grid-type converter and output the physical AC signal of the AC port to the preset complex power system model; wherein, starting the physical grid-type converter can be based on starting the DC power supply to provide DC voltage to the physical grid-type converter.

[0136] It should be noted that the startup of the semi-physical grid converter and the physical grid converter can be controlled based on a startup coordination controller. The coordination controller determines the power commands corresponding to the semi-physical grid converter and the physical grid converter respectively, and sends the power commands to the corresponding controllers of the semi-physical grid converter and the physical grid converter to control the output power of the two converters. It should also be noted that the control method of the test system in this application is not limited by the order of S1 to S3; in actual execution, different sequences can be used.

[0137] Furthermore, based on the above S1 to S3 processes, the test system is started, thereby enabling performance testing of the grid-type converter under test. The performance testing process can be as follows:

[0138] The operating state of a pre-set complex power system model is adjusted to test the response characteristics of semi-physical grid-type converters and physical grid-type converters and their impact characteristics on the pre-set complex power system.

[0139] Methods for adjusting the operating state of complex power systems include switching on and off renewable energy sources, adjusting renewable energy wind speed / solar intensity, switching on and off loads, adjusting load size, switching on and off synchronous generators, adjusting synchronous generator output, switching on and off transformers, switching on and off AC lines, adjusting line parameters, switching on and off faults, and switching on and off grid-connected converters. Faults include three-phase faults, two-phase faults, phase-to-phase faults, and single-phase faults. Fault types include metallic faults and non-metallic faults. Fault points can be located anywhere within the complex power system. Therefore, this application can provide complete grid-connected characteristic test content and system-level characteristic test content. For the test content, at least one of the following data can be collected from the ports of the physical grid-connected converter: voltage and current. At least one of the following data can be calculated: active power, reactive power, active current, reactive current, voltage amplitude, voltage peak value, current peak value, etc., at the ports of the physical grid-connected converter. The collected or calculated data characterizes the performance of the physical grid-connected converter under the corresponding test content, and thus characterizes the performance of the tested grid-connected converter under complex power systems.

[0140] Please see Figure 7 As shown, Figure 7 The semi-physical and physical grid-type converters provided in the embodiments of this application are schematic diagrams of complex power system topologies when energy storage converters are connected.

[0141] For example, a pre-defined complex power system may include photovoltaic power stations, wind power stations, energy storage stations, conventional power stations, load systems, system buses, transmission lines, etc., and the energy storage system in the energy storage station may be a semi-physical or full-power grid-connected energy storage converter. Figure 7In this process, the topology, parameters, and operating status of a complex power system can be flexibly adjusted according to testing requirements, thereby enabling detailed system-level testing of the supporting effect and impact of grid-type energy storage converters on new energy power generation systems.

[0142] It should be understood that the embodiments of this application also provide a control method for a test system for grid-connected converters connected to complex power systems. This method is applied to the test system for grid-connected converters connected to complex power systems, and thus the control method for the test system for grid-connected converters connected to complex power systems includes all the features of the test system for grid-connected converters connected to complex power systems. These effects will not be elaborated here.

[0143] In summary, this application provides a test system and control method for connecting grid-type converters to complex power systems. The system includes a real-time simulation module, a semi-physical grid-type converter controller, a physical grid-type converter, a controllable converter, a DC power supply, and a coordination controller. The real-time simulation module is used to construct and run a large-capacity complex power system model containing large-scale renewable energy sources. Semi-physical and physical grid-type converters are connected to the system through aggregation, achieving large-scale hybrid simulation. The coordination controller is responsible for coordinating the control of the semi-physical and physical grid-type converters. Furthermore, this application effectively solves the challenge of testing physical grid-type converters connected to large-capacity complex power systems, providing a foundation for characteristic testing and system-level characteristic research of grid-type converters. By constructing a large-capacity complex power system containing large-scale renewable energy sources, energy storage converters, and loads in the real-time simulation module, the characteristics of a real large power grid are simulated, providing a realistic environment for testing physical converters. Through power aggregation, closed-loop access to large-scale energy storage is achieved, effectively verifying the supporting role of the converter. This application provides a foundation for the characteristic testing and system-level characteristic research of grid-type converters.

[0144] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0145] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Although this application has disclosed preferred embodiments as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A test system for grid-forming converter access to a complex power system, the test system comprising: A testing process applied to grid-type converters under test in complex power systems, the testing system comprising: The real-time simulation module is used to construct interconnected pre-defined complex power system models and semi-physical grid-type converter primary system models, and to output modulation signals based on the pre-defined complex power system models, semi-physical AC signals, and physical AC signals. A semi-physical grid-type converter controller is connected to the primary system model of the semi-physical grid-type converter to form a semi-physical grid-type converter. The semi-physical grid-type converter controller is used to control the primary system model of the semi-physical grid-type converter so that the primary system model of the semi-physical grid-type converter outputs the semi-physical AC signal to the preset complex power system model. A physical grid-type converter is connected to the preset complex power system model. The physical grid-type converter is used to output the physical AC signal from the AC port to the preset complex power system model. A controllable converter is connected to the preset complex power system model and the physical grid-type converter respectively. The controllable converter is used to modulate based on the modulation signal to output a first electrical signal to the AC port of the physical grid-type converter. The semi-physical grid converter and the physical grid converter together constitute the grid converter under test.

2. The test system of claim 1, wherein, The real-time simulation module is also used to construct a physical grid-type converter interface model, which is connected to the preset complex power system model, the AC port of the physical grid-type converter, and the controllable converter, respectively. The physical grid-type converter interface model is used to process the physical AC signal using a first aggregation method and output it to the preset complex power system model; and the physical grid-type converter interface model is used to output the modulation signal to the controllable converter; wherein, the physical AC signal includes a physical AC current signal, and the first aggregation method refers to multiplying the physical AC current signal by a preset first multiple.

3. The test system for connecting a grid-type converter to a complex power system according to claim 2, characterized in that, The physical grid-type converter interface model includes: The aggregation unit is connected to the AC port of the preset complex power system model and the physical grid-type converter, respectively. The aggregation unit is used to process the physical AC current signal using the first aggregation method and output it to the preset complex power system model.

4. The test system for connecting a grid-type converter to a complex power system according to claim 1, characterized in that, The semi-physical grid-type converter primary system model is also used to process the semi-physical AC signal using a second aggregation method and output it to the preset complex power system model; wherein, the second aggregation method refers to multiplying both the semi-physical AC voltage signal and the semi-physical AC current signal in the semi-physical AC signal to achieve a preset second multiple of power aggregation.

5. The test system for connecting a grid-type converter to a complex power system according to claim 1, characterized in that, Also includes: A coordination controller is connected to both the semi-physical grid converter controller and the physical grid converter. The coordination controller is used to determine the power commands corresponding to the semi-physical grid converter and the physical grid converter based on the operating status of the semi-physical grid converter, the operating status of the physical grid converter, and a preset power command, and then send the power commands to the corresponding semi-physical grid converter controller and the physical grid converter.

6. The test system for connecting a grid-type converter to a complex power system according to claim 5, characterized in that, The coordination controller includes a main coordination controller and multiple sub-coordination controllers. The main coordination controller is connected to each of the sub-coordination controllers, and any one of the sub-coordination controllers is connected to the semi-physical grid converter controller and / or the physical grid converter.

7. The test system for connecting a grid-type converter to a complex power system according to claim 1, characterized in that, The real-time simulation module is used to output a modulated signal based on the preset complex power system model, semi-physical AC signal, and physical AC signal, including: Construct a pre-defined complex power system model, which includes complex power models under various pre-defined operating conditions; Based on the complex power model under each preset operating state, the semi-physical AC signal, and the physical AC signal, output the modulation signal corresponding to the complex power model under each preset operating state.

8. The test system for connecting a grid-type converter to a complex power system according to claim 1, characterized in that, Also includes: A DC power supply is connected to the DC side of the physical grid converter, and the DC power supply is used to provide a second electrical signal to the DC side of the physical grid converter.

9. The test system for connecting a grid-type converter to a complex power system according to claim 1, characterized in that, The real-time simulation module includes: The real-time simulation interface board connects the semi-physical grid-type converter controller to the primary system model of the semi-physical grid-type converter, and the physical grid-type converter connects to the preset complex power system model through the real-time simulation interface board.

10. A control method for a test system of a grid-connected converter connected to a complex power system, characterized in that, include: The real-time simulation module is activated. The real-time simulation module is used to construct an interconnected preset complex power system model and a semi-physical grid-type converter primary system model, and outputs a modulation signal based on the preset complex power system model, the semi-physical AC signal and the physical AC signal. Start the semi-physical grid converter controller, which is used to control the primary system model of the semi-physical grid converter so that the primary system model of the semi-physical grid converter outputs the semi-physical AC signal to the preset complex power system model. Start the controllable converter, which is used to modulate based on the modulation signal to output a first electrical signal to the AC port of the physical grid converter; Start the physical grid-type converter, which is used to output the physical AC signal from the AC port to the preset complex power system model; The preset complex power system model includes complex power models under various preset operating states; The real-time simulation module outputs the modulation signal corresponding to the complex power model under each preset operating state, based on the complex power model, the semi-physical AC signal, and the physical AC signal.

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