A dual hardware-in-the-loop simulation test system and method for grid connection of offshore wind turbines

Abstract

This invention relates to a dual hardware-in-the-loop (HIL) simulation test system and method for offshore wind turbine grid connection. The system includes a real-time simulator, an offshore wind turbine controller, and a power grid simulation device controller. The real-time simulator is used to construct a primary model of the offshore wind turbine, the power grid simulation device, and a typical power grid topology. The offshore wind turbine controller is a converter controller of the same model and software / hardware version as the operational wind turbine. The power grid simulation device controller is a controller of the same model and software / hardware version as the power grid simulation device on a full-scale ground test platform. This invention can serve the verification of key performance indicators in the construction of a full-scale ground test platform for large-capacity offshore wind turbines and the pre-test evaluation of the operation of such a platform, ensuring the accuracy, efficiency, economy, and safety of the tests.

Description

Technical Field

[0001] This invention relates to the field of grid connection testing of offshore wind turbines, and in particular to a dual hardware-in-the-loop simulation test system and method for offshore wind turbine grid connection. Background Technology

[0002] Offshore wind power is one of the main directions of global new energy development, but it faces challenges such as larger turbine sizes, diverse grid connection and transmission methods, and complex operating conditions and grid-related characteristics. To ensure reliable operation and grid-friendly connection of offshore wind power, it is urgent to build comprehensive offshore wind power grid connection testing and inspection capabilities. In offshore wind power field testing, the uncontrollable testing conditions due to natural environment and grid conditions lead to high costs, long cycles, and incomplete results. Countries such as the United States, Denmark, and Germany have established full-scale ground-based testing platforms to comprehensively study the operating characteristics of wind turbine units. my country is also promoting the construction of a national-level offshore wind power research and testing base and building a full-scale ground-based testing platform for wind turbine units.

[0003] The large-capacity offshore wind turbine full-scale ground test platform, centered on the tested offshore wind turbine, includes two major characteristic simulation devices: one on the generation side and one on the grid side. The multi-degree-of-freedom load simulation device on the generation side is used to simulate mechanical loads under wind-wave-current excitation, while the grid simulation device is used to simulate electrical characteristics under different AC / DC transmission methods. The load simulation process has a large mechanical response timescale, primarily affecting the safe operation at the individual turbine level. Grid simulation is crucial for evaluating the grid-connected performance of offshore wind turbines, involving system-level stability issues related to large-scale offshore wind power integration, and has a smaller timescale and faster response, making it of paramount importance.

[0004] As offshore wind turbine power continues to develop from megawatts to 10-megawatts and 20-megawatts, the increase in turbine capacity places increasingly stringent demands on the capacity and performance of grid simulation devices. This manifests in the requirement that grid simulation devices have a rated capacity of hundreds of megavolt-amperes (MVA) and simulate grid-machine interaction during faults / disturbances under complex grid connection conditions. However, existing full-scale ground-based testing methods for large-capacity offshore wind turbines are not yet mature. On the one hand, there is a lack of effective means to verify the performance of large-capacity grid simulation devices at the MVA level, and the grid simulation function still needs optimization and improvement. On the other hand, full-scale ground-based testing and evaluation involves extensive installation and commissioning of large-scale electromechanical equipment, which to some extent affects the safety, economy, and efficiency of the test. Summary of the Invention

[0005] The purpose of this invention is to adapt to the trend of continuous increase in the capacity of single offshore wind turbines and wind farms, grasp the key performance of large offshore wind turbines connected to the grid, and provide a dual hardware-in-the-loop simulation test system and method for offshore wind turbine grid connection. This system serves to verify the key performance indicators of the construction of a full-scale ground test platform for large-capacity offshore wind turbines and to conduct pre-test evaluation of the operation of the full-scale ground test platform for large-capacity offshore wind turbines, so as to ensure the accurate, efficient, economical and safe conduct of the test.

[0006] To achieve the above objectives, the technical solution of the present invention is: a dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system, comprising a real-time simulator, an offshore wind turbine controller, and a power grid simulation device controller; wherein,

[0007] Real-time simulators are used to build primary models of offshore wind turbines, power grid simulation devices, and typical power grid topologies;

[0008] The offshore wind turbine controller is the same model and software / hardware version converter controller as the operational turbine.

[0009] The controller for the power grid simulation device is the same model and software / hardware version controller as the full-size ground test platform power grid simulation device.

[0010] In one embodiment of the present invention, the real-time simulator is RTDS-Novacor. In the host computer simulation software RSCAD, the simulation step size of the main step size simulation interface is set to 50µs, and the step size of the three secondary step size simulation modules is 2µs. Considering that the maximum number of nodes supported by each secondary step size simulation module is 60, two secondary step size simulation modules are used to build the primary model of the inverter module of the power grid simulation device, and one secondary step size simulation module is used to build the primary model of the rectifier module of the power grid simulation device.

[0011] In one embodiment of the present invention, the offshore wind turbine is the test object. The key controlled electrical quantities of the primary circuit of the wind turbine, including grid connection point voltage, grid connection current and DC voltage, are output to the wind power controller in real time through the GTAO board. After coordinate transformation and control algorithm processing, the controller generates reference modulation wave and drive signal, which are output to the simulator in real time through the GTDI board to realize the drive control of the back-to-back converter switching bridge arm of the wind turbine.

[0012] In one embodiment of the present invention, the power grid simulation device is a 90MVA-level output-side transformer-isolated cascaded power electronic power supply, comprising 10 NPC three-level inverter modules, 2 ANPC three-level rectifier modules, and 1 chopper protection module, totaling 158 controlled IGCT switching devices and 5 critical line circuit breakers. The transmission of digital control signals between the real-time simulator and the power grid simulation device controller is achieved using the Aurora communication protocol at a rate of 2GB / s. Simultaneously, the power grid simulation device includes 34 key electrical quantities, including AC port voltage, DC voltage, and bridge arm voltage, which are output to the power grid simulation device controller in real time via the GTAO board to form a closed-loop control loop for the system simulation of the power grid simulation device.

[0013] In one embodiment of the present invention, the system construction includes the following steps:

[0014] S1. Construct primary and secondary system models for offline simulation of a large-capacity power grid simulation device, preliminarily verify the topology design and control loop design of the large-capacity power grid simulation device, and confirm that the fault voltage simulation range, fundamental wave control accuracy, harmonic wave control accuracy, and dynamic response rate meet the design requirements.

[0015] S2. Construct a primary system model for real-time simulation of a large-capacity power grid simulation device, realize the modular configuration of different units and the interaction of physical quantities of multiple modules, and confirm the matching of real-time simulation resources, simulation step size and simulation requirements.

[0016] S3. Construct a secondary system model for real-time simulation of a large-capacity power grid simulation device, carry out hardware-in-the-loop simulation communication interaction debugging, analyze the drive signal sent by the controller and Aurora on the real-time simulation platform, verify the real-time values ​​of key node voltage and current sent by the real-time simulator in the control software of the power grid simulation device controller, and confirm that the relevant delays meet the system design requirements.

[0017] S4. Conduct unit-level hardware-in-the-loop simulation and debugging, respectively realize the real-time interaction and operation simulation between the power grid simulation device controller and the real-time simulation model of the rectifier unit and the real-time simulation model of the inverter unit, and confirm that the DC voltage response of the rectifier unit and the AC voltage response of the inverter unit meet the design requirements.

[0018] S5. Conduct on-loop no-load debugging of the whole machine hardware to realize the cascaded collaborative real-time simulation operation of the large-capacity power grid simulation device's sorting unit and inverter unit, and verify the stability of DC voltage and AC output voltage.

[0019] S6. Conduct on-loop hardware-in-the-loop commissioning of the entire unit. Based on the on-loop hardware-in-the-loop simulation model of the large-capacity grid simulation device, add an independently commissioned on-loop hardware-in-the-loop simulation model of the offshore wind turbine. Verify the stability and dynamic response indicators of the cascaded system under different power levels in steady state, and conduct grid-connected performance simulation tests of the offshore wind turbine.

[0020] This invention also provides a test method for a dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system as described above, comprising: a grid simulation device controller implementing weak grid simulation of a predetermined frequency band based on a built-in impedance model, specifically as follows:

[0021] Set the large-capacity power grid simulation device to active simulation mode and select the power grid impedance model, including the first-order equivalent RL model, the second-order equivalent RL-C model, and the third-order equivalent C-LR-C model;

[0022] Select the frequency band for simulating grid impedance, including the near-synchronous frequency band (30Hz-70Hz), the low-to-medium frequency band (2-99Hz), and the high-frequency band (100-250Hz);

[0023] Set the parameters and virtual impedance value of the bandpass filter for the virtual impedance branch;

[0024] The power grid simulation device controller and the wind turbine converter controller were activated successively.

[0025] In one embodiment of the present invention, the test method further includes: conducting grid-connected simulation tests of wind turbine generators: active power frequency control capability test, reactive power voltage control capability test, grid-connected operation adaptability test, fault ride-through capability test, and power quality test; and introducing transient oscillation feature extraction of the fault ride-through process to realize the grid-connected simulation test of wind turbine generators, specifically implemented as follows:

[0026] Set the large-capacity power grid simulation device to active simulation mode, and set the power grid impedance model to a second-order equivalent RL-C model and a third-order equivalent C-LR-C model respectively;

[0027] The frequency band for simulating grid impedance is selected as the near-synchronous frequency band (30Hz-70Hz);

[0028] Set the parameters and virtual impedance value of the bandpass filter for the virtual impedance branch;

[0029] The power grid simulation device controller and the wind turbine converter controller were started successively to complete the low-high voltage cascading fault simulation and record the fault ride-through voltage and power response curves.

[0030] Extract fault transient characteristics during low voltage ride-through, including the lowest fault voltage point, transient oscillation frequency, and transient decay rate;

[0031] Extract fault transient characteristics during high-voltage ride-through, including the highest fault voltage point, transient oscillation frequency, and transient decay rate;

[0032] Evaluate the DC voltage stability and stability margin of wind turbine units during transient oscillation processes.

[0033] In one embodiment of the present invention, the test method further includes: conducting grid-connected simulation test projects for grid-connected offshore wind turbines: ultimate short-circuit current test, ultimate strong grid operation test, inertia response test, black start test, and phase change test, respectively realizing the evaluation of the unit's short-circuit current support capability, ultimate short-circuit ratio operation capability, inertia response rate evaluation, black start rate and stability evaluation, and voltage regulation response characteristics evaluation.

[0034] This invention also provides a test method for a dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system as described above, comprising: a grid simulation device controller simulating complex grid characteristics of a flexible direct power transmission scenario based on fault simulation curve tracking, specifically implemented as follows:

[0035] Set the primary and secondary parameters of the offshore wind power flexible DC transmission system, including the sending-end converter station, receiving-end converter station, DC submarine cable, AC submarine cable, and offshore wind turbine.

[0036] Verify the consistency of response between the pure digital simulation model and the hardware-in-the-loop simulation model of the offshore wind turbine, focusing on evaluating the fault voltage protection characteristics, active and reactive power response values ​​during the fault, active power recovery rate after fault clearance, and reactive power exit rate after fault clearance.

[0037] Start the simulation model of the wind power flexible direct transmission system, set faults, and record the fault voltage at the wind turbine grid connection point;

[0038] To improve the control accuracy of the positive and negative sequence components and the main harmonic components of the power frequency, a three-PIR closed-loop tracking control strategy in a rotating coordinate system is adopted. The fault voltage to be reproduced is pre-analyzed in the spectrum and transformed to the dq rotating coordinate system for comparison with the actual output voltage to form a negative feedback control loop. The PI controller of control channel 1 is used to realize basic voltage tracking, the PR controller of control channel 2 is used to optimize the tracking of the fundamental negative sequence quantity, and the PR controller of control channel 3 is used to optimize the tracking of the main harmonic components.

[0039] Set the large-capacity power grid simulation device to waveform reproduction simulation mode, and start the power grid simulation device controller and the wind turbine converter controller in sequence.

[0040] Compared with the prior art, the present invention has the following beneficial effects: The present invention can serve the verification of key performance indicators in the construction of a full-size ground test platform for large-capacity offshore wind turbines and the pre-test evaluation of the operation of a full-size ground test platform for large-capacity offshore wind turbines, so as to ensure that the test is carried out accurately, efficiently, economically and safely. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the offshore wind turbine grid connection simulation test system according to an embodiment of the invention;

[0042] Figure 2 This is a topology diagram of a large-capacity power grid simulation device according to an embodiment of the invention;

[0043] Figure 3 This is a schematic diagram illustrating the steps involved in building a grid-connected simulation test system for offshore wind turbines, as described in the invention.

[0044] Figure 4 This is a schematic diagram of the equivalent model of a weak power grid according to an embodiment of the invention;

[0045] Figure 5 This is a schematic diagram of PIR control closed-loop tracking control in Embodiment 3 of the invention. Detailed Implementation

[0046] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0047] This invention provides a dual hardware-in-the-loop offshore wind turbine grid connection simulation test system, including a real-time simulator, an offshore wind turbine controller, and a power grid simulation device controller; wherein,

[0048] Real-time simulators are used to build primary models of offshore wind turbines, power grid simulation devices, and typical power grid topologies;

[0049] The offshore wind turbine controller is the same model and software / hardware version converter controller as the operational turbine.

[0050] The controller for the power grid simulation device is the same model and software / hardware version controller as the full-size ground test platform power grid simulation device.

[0051] The present invention also provides a test method for a dual hardware-in-the-loop offshore wind turbine grid connection simulation test system as described above, comprising the following steps:

[0052] S1. Construct primary and secondary system models for offline simulation of a large-capacity power grid simulation device, preliminarily verify the topology design and control loop design of the large-capacity power grid simulation device, and confirm that the fault voltage simulation range, fundamental wave control accuracy, harmonic wave control accuracy, and dynamic response rate meet the design requirements.

[0053] S2. Construct a primary system model for real-time simulation of a large-capacity power grid simulation device, realize the modular configuration of different units and the interaction of physical quantities of multiple modules, and confirm the matching of real-time simulation resources, simulation step size and simulation requirements.

[0054] S3. Construct a secondary system model for real-time simulation of a large-capacity power grid simulation device, carry out hardware-in-the-loop simulation communication interaction debugging, analyze the drive signal sent by the controller and Aurora on the real-time simulation platform, verify the real-time values ​​of key node voltage and current sent by the real-time simulator in the control software of the power grid simulation device controller, and confirm that the relevant delays meet the system design requirements.

[0055] S4. Conduct unit-level hardware-in-the-loop simulation and debugging, respectively realize the real-time interaction and operation simulation between the power grid simulation device controller and the real-time simulation model of the rectifier unit and the real-time simulation model of the inverter unit, and confirm that the DC voltage response of the rectifier unit and the AC voltage response of the inverter unit meet the design requirements.

[0056] S5. Conduct on-loop no-load debugging of the whole machine hardware to realize the cascaded collaborative real-time simulation operation of the large-capacity power grid simulation device's sorting unit and inverter unit, and verify the stability of DC voltage and AC output voltage.

[0057] S6. Conduct on-loop hardware-in-the-loop commissioning of the entire unit. Based on the on-loop hardware-in-the-loop simulation model of the large-capacity power grid simulation device, add an independently commissioned on-loop simulation model of the offshore wind turbine to verify the stability and dynamic response indicators of the cascaded system under different power levels in steady state.

[0058] The following are specific implementation examples of the present invention.

[0059] An embodiment of the present invention (a dual hardware-in-the-loop offshore wind turbine grid connection simulation test system) is attached. Figure 1 As shown, the system comprises three main subsystems: a real-time simulator, an offshore wind turbine controller, and a power grid simulation device controller. The real-time simulator, RTDS-Novacor, is used to construct primary models of the offshore wind turbine, the power grid simulation device, and a typical power grid topology. In the host computer simulation software RSCAD-FX2.1.1, the main step size simulation interface is set to 50µs, and the step size for the three secondary step size simulation modules is 2µs. Considering that each secondary step size simulation module supports a maximum of 60 nodes, two secondary step size simulation modules are used to build the primary model of the inverter module of the power grid simulation device, and one secondary step size simulation module is used to build the primary model of the rectifier module of the power grid simulation device.

[0060] The wind power tested in the simulation experiment is a 16MW direct-drive full-power converter type unit. The key controlled electrical quantities such as grid connection point voltage, grid connection current, and DC voltage of the primary circuit simulation model of the wind turbine are output to the wind power controller in real time through the GTAO board. After coordinate transformation and control algorithm processing, the controller generates reference modulation wave and drive signal, which are then output to the simulator in real time through the GTDI board to realize the drive control of the back-to-back converter switching bridge arm of the wind turbine.

[0061] The power grid simulation device used in the simulation experiment was a 90MVA output-side transformer-isolated cascaded power electronic power supply, comprising 10 NPC three-level inverter modules, 2 ANPC three-level rectifier modules, and 1 chopper protection module, totaling 158 controlled IGCT switching devices and 5 critical circuit breakers. The transmission of these numerous digital control signals between the RTDS real-time simulator and the power grid simulation device controller was achieved using the Aurora communication protocol at a rate of 2GB / s. Simultaneously, 34 key electrical quantities, including AC port voltage, DC voltage, and bridge arm voltage, were output in real-time to the power grid simulation device controller via the GTAO board, forming a closed-loop control circuit for the power grid simulation system.

[0062] The detailed topology of the power grid simulation device is attached. Figure 2 As shown, in addition to the aforementioned NPC three-level inverter module, ANPC three-level rectifier module, and chopper protection module, it also includes 2 three-phase transformers and 15 single-phase transformers. The three-phase transformers and ANPC three-level rectifier modules are connected in series to achieve a stable conversion from the three-phase power grid AC voltage of 35kV to the DC bus voltage of 5000V. The 10 ANPC three-level inverter modules are divided into 5 groups. Every 2 inverter modules output to the primary side of the 3 single-phase transformers using an H-bridge connection with 3 phases. The last 5 groups of inverter modules are cascaded on the secondary side of the single-phase transformers to boost the voltage, ensuring that the power grid simulation device has a rated voltage output capability of 35kV and a fault voltage dynamic simulation capability of 0-1.5pu.

[0063] The construction of the dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system of this invention is implemented in a layered and step-by-step manner, as shown in the appendix. Figure 3 As shown, it includes the following steps:

[0064] S1. Construct primary and secondary system models for offline simulation of a large-capacity power grid simulation device, preliminarily verify the topology design and control loop design of the simulation device, and confirm that the fault voltage simulation range, fundamental wave control accuracy, harmonic wave control accuracy, and dynamic response rate meet the design requirements.

[0065] S2. Construct a primary system model for real-time simulation of a large-capacity power grid simulation device, realize the modular configuration of different units and the interaction of physical quantities of multiple modules, and confirm the matching of real-time simulation resources, simulation step size and simulation requirements.

[0066] S3. Construct a secondary system model for real-time simulation of a large-capacity power grid simulation device, carry out hardware-in-the-loop simulation communication interaction debugging, analyze the drive signal sent by the controller and Aurora on the real-time simulation platform, verify the real-time values ​​of key node voltage and current sent by the real-time simulator in the controller control software, and confirm that the relevant delays meet the system design requirements.

[0067] S4. Conduct unit-level hardware-in-the-loop simulation and debugging, respectively realize the real-time interaction and operation simulation between the controller of the large-capacity power grid simulation device and the real-time simulation model of the rectifier unit and the real-time simulation model of the inverter unit, and confirm that the DC voltage response of the rectifier unit and the AC voltage response of the inverter unit meet the design requirements.

[0068] S5. Conduct on-loop no-load debugging of the whole machine hardware to realize the cascaded collaborative real-time simulation operation of the large-capacity power grid simulation device's sorting unit and inverter unit, and verify the stability of DC voltage and AC output voltage.

[0069] S6. Conduct on-loop hardware-in-the-loop commissioning of the entire unit. Based on the on-loop hardware-in-the-loop simulation model of the power grid simulation device, add an independently commissioned on-loop simulation model of the offshore wind turbine to verify the stability and dynamic response indicators of the cascaded system under different power levels in steady state.

[0070] In this simulation system, the power grid simulation device controller uses a built-in impedance model to simulate a weak power grid in a specific frequency band. The specific implementation steps include:

[0071] (1) Set the power grid simulation device to active simulation mode and select the power grid impedance model, including the first-order equivalent RL model, the second-order equivalent RL-C model, and the third-order equivalent C-LR-C model. The equivalent system for weak power grids is attached. Figure 3 As shown.

[0072] (2) Select the frequency band for simulating grid impedance, including the near-synchronous frequency band (30Hz-70Hz), the low-to-medium frequency band (2-99Hz), and the high-frequency band (100-250Hz);

[0073] (3) Set the parameters and virtual impedance value of the bandpass filter for the virtual impedance branch;

[0074] (4) Start the power grid simulation device controller and the wind turbine converter controller in sequence.

[0075] In this simulation system, the power grid simulation device controller simulates the complex power grid characteristics of the flexible DC transmission scenario based on fault simulation curve tracking. The specific implementation steps include:

[0076] (1) Set the primary and secondary parameters of the offshore wind power flexible DC transmission system, including the sending-end converter station, receiving-end converter station, DC submarine cable, AC submarine cable, and offshore wind turbine.

[0077] (2) Verify the response consistency between the pure digital simulation model and the hardware-in-the-loop simulation model of the offshore wind turbine, and focus on evaluating the fault voltage protection characteristics, active and reactive power response values ​​during the fault, active power recovery rate after fault clearance, and reactive power exit rate after fault clearance.

[0078] (3) Start the simulation model of the wind power flexible direct transmission system, set the fault, and record the fault voltage at the wind turbine grid connection point;

[0079] (4) To improve the control accuracy of the positive and negative sequence components and the main harmonic components of the power frequency, a three-PIR closed-loop tracking control strategy in a rotating coordinate system is adopted. The control loop structure is shown in the attached figure. Figure 5 As shown; the fault voltage to be reproduced is pre-analyzed in the spectrum and transformed into the dq rotating coordinate system to be compared with the actual output voltage to form a negative feedback control loop. The PI controller of control channel 1 is used to realize basic voltage tracking, the PR controller of control channel 2 is used to optimize the tracking of the fundamental negative sequence quantity, and the PR controller of control channel 3 is used to optimize the tracking of the main harmonic components.

[0080] (5) Set the power grid simulation device to waveform reproduction simulation mode and start the power grid simulation device controller and wind turbine converter controller in sequence.

[0081] The dual hardware-in-the-loop offshore wind turbine grid-connection simulation test system can conduct the following wind turbine grid-connection test items: active power frequency control capability test, reactive power voltage control capability test, grid-connected operation adaptability test, fault ride-through capability test, and power quality test. Compared with conventional wind turbine grid-connection simulation test methods, its key feature is the introduction of transient oscillation feature extraction during the fault ride-through process. Specific steps include:

[0082] (1) Set the power grid simulation device to active simulation mode, and set the power grid impedance model to the second-order equivalent RL-C model and the third-order equivalent C-LR-C model respectively;

[0083] (2) Select the near-synchronous frequency band for the grid impedance simulation (30Hz-70Hz);

[0084] (3) Set the parameters and virtual impedance value of the bandpass filter for the virtual impedance branch;

[0085] (4) Start the power grid simulation device controller and wind turbine converter controller in sequence to complete the low-high voltage cascading fault simulation and record the fault ride-through voltage and power response curves.

[0086] (5) Extract the transient characteristics of the fault during low voltage ride-through, including the lowest fault voltage point, transient oscillation frequency, and transient decay rate;

[0087] (6) Extract the transient characteristics of the fault during high voltage ride-through, including the highest fault voltage, transient oscillation frequency, and transient decay rate;

[0088] (7) Evaluate the DC voltage stability and stability margin of the wind turbine during transient oscillation.

[0089] In addition to conducting grid connection tests on conventional grid-connected wind turbines, the dual hardware-in-the-loop offshore wind turbine grid connection simulation test system is also used to conduct grid connection tests on grid-connected offshore wind turbines. The newly added wind power test contents include: ultimate short-circuit current test, ultimate strong grid operation test, inertia response test, black start test, and phase change test, which respectively realize the evaluation of the unit's short-circuit current support capability, ultimate short-circuit ratio operation capability, inertia response rate, black start rate and stability, and voltage regulation response characteristics.

[0090] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A dual hardware-in-the-loop simulation test system for offshore wind turbine grid connection, characterized in that, This includes real-time simulators, offshore wind turbine controllers, and power grid simulation device controllers; among them, Real-time simulators are used to build primary models of offshore wind turbines, power grid simulation devices, and typical power grid topologies; The offshore wind turbine controller is the same model and software / hardware version converter controller as the operational turbine. The power grid simulation device controller is the same model and software / hardware version controller as the full-size ground test platform power grid simulation device. The real-time simulator is RTDS-Novacor. In the host computer simulation software RSCAD, the simulation step size of the main step size simulation interface is set to 50us, and the step size of the three sub-step size simulation modules is 2us. Considering that the maximum number of nodes supported by each sub-step size simulation module is 60, two sub-step size simulation modules are used to build the primary model of the inverter module of the power grid simulation device, and one sub-step size simulation module is used to build the primary model of the rectifier module of the power grid simulation device. System construction includes the following steps: S1. Construct primary and secondary system models for offline simulation of a large-capacity power grid simulation device, preliminarily verify the topology design and control loop design of the large-capacity power grid simulation device, and confirm that the fault voltage simulation range, fundamental wave control accuracy, harmonic wave control accuracy, and dynamic response rate meet the design requirements. S2. Construct a primary system model for real-time simulation of a large-capacity power grid simulation device, realize the modular configuration of different units and the interaction of physical quantities of multiple modules, and confirm the matching of real-time simulation resources, simulation step size and simulation requirements. S3. Construct a secondary system model for real-time simulation of a large-capacity power grid simulation device, carry out hardware-in-the-loop simulation communication interaction debugging, analyze the drive signal sent by the controller and Aurora on the real-time simulation platform, verify the real-time values ​​of key node voltage and current sent by the real-time simulator in the control software of the power grid simulation device controller, and confirm that the relevant delays meet the system design requirements. S4. Conduct unit-level hardware-in-the-loop simulation and debugging, respectively realize the real-time interaction and operation simulation between the power grid simulation device controller and the real-time simulation model of the rectifier unit and the real-time simulation model of the inverter unit, and confirm that the DC voltage response of the rectifier unit and the AC voltage response of the inverter unit meet the design requirements. S5. Conduct on-loop no-load debugging of the whole machine hardware to realize the cascaded collaborative real-time simulation operation of the large-capacity power grid simulation device's sorting unit and inverter unit, and verify the stability of DC voltage and AC output voltage. S6. Conduct on-loop hardware-in-the-loop commissioning of the entire unit. Based on the on-loop hardware-in-the-loop simulation model of the large-capacity grid simulation device, add an independently commissioned on-loop hardware-in-the-loop simulation model of the offshore wind turbine. Verify the stability and dynamic response indicators of the cascaded system under different power levels in steady state, and conduct grid-connected performance simulation tests of the offshore wind turbine.

2. The dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system according to claim 1, characterized in that, The offshore wind turbine is the test object. The key controlled electrical quantities of the primary circuit of the wind turbine, including grid connection point voltage, grid connection current and DC voltage, are output to the wind power controller in real time through the GTAO board. After coordinate transformation and control algorithm processing, the controller generates reference modulation wave and drive signal, which are output to the simulator in real time through the GTDI board to realize the drive control of the back-to-back converter switching bridge arm of the wind turbine.

3. The dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system according to claim 1, characterized in that, The power grid simulation device is a 90MVA-class output-side transformer-isolated cascaded power electronic power supply, comprising 10 NPC three-level inverter modules, 2 ANPC three-level rectifier modules, and 1 chopper protection module, with a total of 158 controlled IGCT switching devices and 5 critical line circuit breakers. The transmission of digital control signals between the real-time simulator and the power grid simulation device controller is achieved using the Aurora communication protocol at a rate of 2GB / s. Simultaneously, the power grid simulation device outputs 34 key electrical quantities, including AC port voltage, DC voltage, and bridge arm voltage, to the power grid simulation device controller in real time via GTAO boards to form a closed-loop control loop for the system simulation of the power grid simulation device.

4. A test method for a dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system according to any one of claims 1-3, characterized in that, include: The power grid simulation device controller uses a built-in impedance model to simulate weak power grids within a predetermined frequency band. The specific implementation is as follows: Set the large-capacity power grid simulation device to active simulation mode and select the power grid impedance model, including the first-order equivalent RL model, the second-order equivalent RL-C model, and the third-order equivalent C-LR-C model; Select the grid impedance simulation frequency band, including the near-synchronous frequency band of 30Hz-70Hz, the mid-low frequency band of 2-99Hz, and the high frequency band of 100-250Hz; Set the parameters and virtual impedance value of the bandpass filter for the virtual impedance branch; The power grid simulation device controller and the wind turbine converter controller were activated successively.

5. The test method for a dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system according to claim 4, characterized in that, The transient oscillation feature extraction of the fault ride-through process is introduced to realize the grid connection simulation test of wind turbine units. The specific implementation is as follows: Set the large-capacity power grid simulation device to active simulation mode, and set the power grid impedance model to a second-order equivalent RL-C model and a third-order equivalent C-LR-C model respectively; The frequency band for simulating grid impedance is selected as the near-synchronous frequency band of 30Hz-70Hz; Set the parameters and virtual impedance value of the bandpass filter for the virtual impedance branch; The power grid simulation device controller and the wind turbine converter controller were started successively to complete the low-high voltage cascading fault simulation and record the fault ride-through voltage and power response curves. Extract fault transient characteristics during low voltage ride-through, including the lowest fault voltage point, transient oscillation frequency, and transient decay rate; Extract fault transient characteristics during high-voltage ride-through, including the highest fault voltage point, transient oscillation frequency, and transient decay rate; Evaluate the DC voltage stability and stability margin of wind turbine units during transient oscillation processes.

6. The test method for a dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system according to claim 4 or 5, characterized in that, The system can be used to conduct grid-connected simulation tests of grid-connected offshore wind turbines, including ultimate short-circuit current tests, ultimate strong grid operation tests, inertia response tests, black start tests, and phase change tests. These tests enable the evaluation of the unit's short-circuit current support capability, ultimate short-circuit ratio operation capability, inertia response rate, black start rate and stability, and voltage regulation response characteristics.

7. A test method for a dual hardware-in-the-loop offshore wind turbine grid-connected simulation test system according to any one of claims 1-3, characterized in that, include: The power grid simulation device controller simulates the complex power grid characteristics of a flexible DC transmission scenario based on fault simulation curve tracking. The specific implementation is as follows: Set the primary and secondary parameters of the offshore wind power flexible DC transmission system, including the sending-end converter station, receiving-end converter station, DC submarine cable, AC submarine cable, and offshore wind turbine. Verify the consistency of response between the pure digital simulation model and the hardware-in-the-loop simulation model of the offshore wind turbine, focusing on evaluating the fault voltage protection characteristics, active and reactive power response values ​​during the fault, active power recovery rate after fault clearance, and reactive power exit rate after fault clearance. Start the simulation model of the wind power flexible direct transmission system, set faults, and record the fault voltage at the wind turbine grid connection point; To improve the control accuracy of the positive and negative sequence components and the main harmonic components of the power frequency, a three-PIR closed-loop tracking control strategy in a rotating coordinate system is adopted. The fault voltage to be reproduced is pre-analyzed in the spectrum and transformed into a dq rotating coordinate system to be compared with the actual output voltage to form a negative feedback control loop. The PI controller of control channel 1 is used to realize basic voltage tracking, the PR controller of control channel 2 is used to optimize the tracking of the fundamental negative sequence quantity, and the PR controller of control channel 3 is used to optimize the tracking of the main harmonic components. Set the large-capacity power grid simulation device to waveform reproduction simulation mode, and start the power grid simulation device controller and the wind turbine converter controller in sequence.

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