Detection equipment suitable for high-low wearing performance and control method

Abstract

The invention discloses detection equipment suitable for high and low penetration performance and a control method, and belongs to the technical field of power grid fault detection, the detection equipment comprises a converter, an IO board, high penetration generation equipment, low penetration generation equipment, a CAN communication module, an upper computer, a branch parallel contactor switch for connecting a power grid with the converter, the high penetration generation equipment and the low penetration generation equipment are connected with a branch, and the branch parallel contactor switch is connected with the CAN communication module. The IO board is connected with the contactor switch, the high-pass generation device and the low-pass generation device, and the converter is connected with the upper computer through the CAN communication module. Through operation steps of contactor control and the like, three ride-through conditions of high voltage ride-through, low voltage ride-through and high and low voltage chain ride-through are simulated and controlled, and the high and low voltage ride-through performance of a unit is detected according to waveform change of sampling parameters before and after high and low voltage ride-through of a model. The high-low penetration capability of the unit is tested through the detection equipment, so that the influence of such faults on power generation is reduced, the safety of workers is maintained, and the power generation capability of the fan is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid fault detection, and in particular relates to a detection device and a control method suitable for high and low penetration performance. Background Art

[0002] Since the unit may experience grid failure or disturbance within a certain period of time during operation, causing the voltage to rise or fall, which in turn leads to the problem of wind turbine disconnection from the grid, high and low voltage penetration detection equipment has become an important part of converter detection. A high and low voltage penetration retrieval device has been announced in the patented integrated high and low voltage penetration test system, but due to technical defects, it lacks the ability to detect high and low voltage linkage, and lacks intuitive oscilloscope function. Summary of the invention

[0003] In order to solve the above-mentioned problems, the present invention proposes: a detection device suitable for high and low wear performance, including an inverter, an IO board, a high wear generating device, a low wear generating device, a CAN communication module, and a host computer. The branch connecting the power grid and the inverter is connected to a contactor switch in parallel, the high wear generating device and the low wear generating device are connected to the branch, the IO board is connected to the contactor switch, the high wear generating device, and the low wear generating device, and the inverter is connected to the host computer through the CAN communication module.

[0004] Furthermore, the IO board provides 24V power to the test equipment through a DC analog power supply.

[0005] Furthermore, the IO board includes an analog signal module, the analog signal module includes a plurality of analog output terminals, and each of the analog output terminals outputs a related switch signal corresponding to a device.

[0006] Furthermore, the analog signal module includes a plurality of analog input terminals, and the output of each analog input terminal corresponds to a related enabling state of a device.

[0007] Furthermore, the CAN communication module is a CAN communication to Ethernet module.

[0008] A control method for high and low wear performance detection equipment comprises the following steps:

[0009] Step S1: Analyze the requirements for high and low wear and determine the relevant parameters;

[0010] Step S2: Determine the connection of relevant circuit structures and construct a high and low voltage trigger circuit based on capacitors and inductors;

[0011] Step S3: construct a device connection diagram and trigger high and low voltage ride-through through the IO control board;

[0012] Step S4: Observe the relevant waveforms before and after the high and low voltage ride-through through the host computer.

[0013] Furthermore, in step S1, the low voltage ride-through requirement is: for wind turbines that are not disconnected from the grid during the voltage drop, the active power should be restored to the output power corresponding to the actual wind conditions at a power change rate of at least 10% Pn / s from the moment the voltage returns to normal; dynamic reactive power support capability: when a three-phase symmetrical voltage drop occurs at the grid connection point of the wind turbine, the wind turbine should respond quickly from the moment the voltage drop occurs, and support the voltage recovery by injecting capacitive reactive current; the specific requirements are as follows:

[0014] The response time of dynamic capacitive reactive current control is no more than 75ms from the moment the voltage drop occurs at the grid connection point, and the capacitive reactive current is continuously injected during the voltage fault period;

[0015] The dynamic capacitive reactive current provided by the wind turbine should meet the requirements of formula (1):

[0016] I TC ≥1.5×(0.9-U T )I n ,(0.2≤U T ≤0.9)……………(1)

[0017] When a three-phase asymmetric voltage drop occurs at the wind turbine grid connection point, the wind turbine should inject capacitive reactive current to support voltage recovery;

[0018] The requirements for high voltage ride-through are as follows: Active power output: For wind turbines that are not disconnected from the grid, the active power fluctuation amplitude should be within the range of ±50% Pn at the time of voltage increase and the time of voltage recovery, and the fluctuation time should not exceed 80ms; during the voltage increase period, the output active power fluctuation amplitude should be within the range of ±5% Pn; after the voltage returns to normal, the output power should be the output power corresponding to the actual wind conditions; Dynamic reactive power support capability: When a three-phase symmetrical voltage increase occurs at the wind turbine grid connection point, the wind turbine should respond quickly from the moment the voltage increase occurs, and support voltage recovery by injecting inductive reactive current; The specific requirements are as follows:

[0019] The response time of dynamic inductive reactive current control is no more than 40ms from the moment the voltage rise occurs at the grid connection point, and the inductive reactive current is continuously injected during the voltage fault period;

[0020] The dynamic inductive reactive current provided by the wind turbine should meet the requirements of formula (2):

[0021] I TL ≥1.5×(U T -1.1)I n ,(1.1≤U T ≤1.3)…………(2)

[0022] When the three-phase asymmetric voltage rises at the wind turbine grid connection point, the wind turbine should inject inductive reactive current to support voltage recovery;

[0023] Fault voltage cascading failure test requirements: When a low or high voltage cascading fault occurs, when the low voltage ride-through ends and the grid voltage recovers to above 0.9pu, the active power should be restored to the output corresponding to the actual wind conditions at a power change rate of at least 10% Pn / s. During the voltage rise period, the output power is maintained at the power recovery characteristic after the low voltage ride-through ends or the output power corresponding to the actual wind conditions.

[0024] Furthermore, in step S2, the current limiting impedance Z sr Limit the impact of fault voltage on the power grid and other operating units in the wind farm. Before and after the voltage fault occurs, the current limiting impedance can be short-circuited using the bypass switch CB1.

[0025] Z sc To short-circuit the impedance, close the short-circuit switch CB2 and connect the three or two phases of the short-circuit impedance together to generate the voltage drop required by the test at the test point.

[0026] C L is the boost branch capacitor, R d For the boost branch resistor, close the short-circuit switch CB3, and connect the three-phase or two-phase boost resistor and capacitor together to generate the required voltage increase at the test point.

[0027] Further, as described in step S3, the grid voltage drop simulation timing is as follows: in the initial state, K1 is closed and K2 is disconnected. After the test starts, the K1 circuit breaker is disconnected, and the current limiting reactor group is connected in series to the circuit. After 5ms, the K2 circuit breaker is closed, and the three phases or two phases of the branch composed of the boost impedance and the boost damping resistor are connected together to generate the required voltage increase at the test point;

[0028] Low voltage topology: In the initial state, K1 is closed and K3 is disconnected. After the test starts, the K1 circuit breaker is disconnected, and the current limiting reactor group is connected in series to the circuit. After 5ms, the K3 circuit breaker is closed, and the three or two phases of the branch composed of the step-down inductive reactance are connected together to generate the required voltage reduction at the test point.

[0029] Furthermore, in step S4, by controlling the grid-side voltage to change between low and high voltages twice in a row, it is checked whether the converter can work stably after the change and the accuracy of the waveform is checked.

[0030] The beneficial effects of the present invention are as follows: as the country vigorously develops the wind power industry, the continuous updating of relevant national standards has put forward higher requirements on the performance of the inverter. In terms of high and low penetration, it is not only required to complete high penetration and low penetration tests, but also the concept of high and low penetration chain crossing is proposed, which puts forward higher requirements on high and low penetration ability detection equipment. The equipment has high and low penetration chain detection capabilities and adds an oscilloscope recording function.

[0031] The present invention constructs a high and low penetration detection model, artificially triggers the rise or fall of the power grid within a certain period of time through a fault trigger device, collects relevant data to verify the high and low penetration capabilities of the unit, and tests the high and low penetration capabilities of the unit through detection equipment, thereby reducing the impact of such faults on power generation, maintaining the safety of workers, and effectively improving the power generation capacity of the wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Wiring diagrams for high and low voltage devices;

[0033] Figure 2 Schematic diagram of high and low voltage ride through of wind turbine;

[0034] Figure 3 Line chart of high and low voltage ride-through requirements for wind turbines;

[0035] Figure 4 Schematic diagram of high voltage fault generating device;

[0036] Figure 5 Schematic diagram of low voltage fault generating device;

[0037] Figure 6 Line chart of voltage drop allowable error during low voltage no-load test;

[0038] Figure 7 Line chart of voltage rise allowable error during high voltage no-load test;

[0039] Figure 8 Fault ride-through test schematic diagram;

[0040] Fig. 9 Fault continuous ride-through test flow chart;

[0041] Fig.10 Fault continuous ride-through test simulation results diagram. DETAILED DESCRIPTION

[0042] Example 1

[0043] In order to make the technical means and objectives of the present invention easy to understand, the present invention is further described below in combination with specific embodiments. A detection device suitable for high and low wear performance, such as Figure 1As shown, it includes an inverter, an IO board, a high-throughput generating device, a low-throughput generating device, a CAN communication module, and a host computer. The branch connecting the power grid and the inverter is connected to a contactor switch in parallel, the high-throughput generating device and the low-throughput generating device are connected to the branch, the IO board is connected to the contactor switch, the high-throughput generating device, and the low-throughput generating device, and the inverter is connected to the host computer through the CAN communication module.

[0044] The IO board is connected to the high and low voltage fault generation module and the KM1 switch, and the IO control is used to switch between normal, high voltage, low voltage and high and low voltage interlocking conditions. The inverter related parameters are connected to the host computer through the CAN communication module.

[0045] The DC analog power supply provides 24V power to the IO board of the test equipment;

[0046] The host computer displays the voltage waveform of the device when it is high or low;

[0047] The high and low voltage generation modules of the high voltage wear generating device and the low voltage wear generating device simulate the three-phase voltage source in the case of high and low voltage wear;

[0048] The IO board includes an analog signal module, and the analog signal module includes a plurality of analog output terminals, and each of the analog output terminals outputs a switch signal corresponding to a device, and the analog signal module includes a plurality of analog input terminals, and each of the analog input terminals outputs an enable state corresponding to a device;

[0049] The CAN communication device includes a CAN communication to Ethernet module;

[0050] The present invention aims at the problem of high and low pass-through of the unit caused by power grid fault or disturbance, and provides a universal high and low pass-through performance detection device for auxiliary converter. The technical solution of the present invention to solve the above problem is to provide a universal high and low pass-through performance detection device.

[0051] Example 2

[0052] A control method for high and low wear performance detection equipment, the specific detailed method steps are as follows:

[0053] Step S1: Figure 3 As shown, analyze the high and low wear requirements and determine the relevant parameters;

[0054] Step S2: Determine the relevant circuit structure connection and construct a high and low voltage trigger circuit based on capacitor and inductor such as Figure 4 , Figure 5 As shown;

[0055] Step S3: Construct a device connection diagram, such as Figure 2 As shown, high and low voltage ride-through is triggered through the IO control board;

[0056] Step S4: Fig.10 As shown, the relevant waveforms before and after the high and low voltage ride-through are observed through the host computer.

[0057] This example is described in conjunction with the accompanying drawings to better illustrate the technology and purpose of the invention.

[0058] When a fault or disturbance occurs in the power grid and causes the voltage at the test point to rise, the line voltage (phase voltage) at the wind turbine test point will increase. Figure 3 When the voltage contour line of curve 2 is within the area below the curve 2, or when a fault or disturbance occurs in the power grid causing the voltage at the test point to drop, the line voltage (phase voltage) at the wind turbine test point ... Figure 3 When in the area above the voltage contour line of curve 1, the wind turbine must ensure continuous operation without disconnecting from the grid; otherwise, the wind turbine is allowed to be cut out.

[0059] As described in step S1, the fault voltage ride-through of the wind turbine includes low voltage ride-through, high voltage ride-through, and fault voltage cascading fault. The specific requirements are as follows:

[0060] Low voltage ride-through requirements, wind turbines should have Figure 3 The ability to operate continuously without disconnecting from the grid within the voltage-time range specified by curve 1. The requirements are as follows: For wind turbines that are not disconnected from the grid during voltage drops, the active power should be restored to the output power corresponding to the actual wind conditions at a power change rate of at least 10% Pn / s from the moment the voltage returns to normal; Dynamic reactive power support capability: When a three-phase symmetrical voltage drop occurs at the wind turbine grid connection point, the wind turbine should respond quickly from the moment the voltage drop occurs, and support voltage recovery by injecting capacitive reactive current. The specific requirements are as follows:

[0061] The response time of dynamic capacitive reactive current control is no more than 75ms from the moment the voltage drop occurs at the grid connection point, and the capacitive reactive current is continuously injected during the voltage fault period;

[0062] The dynamic capacitive reactive current provided by the wind turbine should meet the requirements of formula (1):

[0063] I TC ≥1.5×(0.9-U T )I n ,(0.2≤U T ≤0.9)……………(1)

[0064] When a three-phase asymmetric voltage drop occurs at the wind turbine grid connection point, the wind turbine should inject capacitive reactive current to support voltage recovery.

[0065] High voltage ride-through requirements: Wind turbines should have Figure 3The ability to operate continuously without disconnecting from the grid within the voltage-time range specified by the middle curve 2. The requirements are as follows: Active power output: For wind turbines that are not disconnected from the grid, the active power fluctuation amplitude should be within the range of ±50%Pn when the voltage rises and when the voltage returns to normal, and the fluctuation time should not exceed 80ms; during the voltage rise period, the output active power fluctuation amplitude should be within the range of ±5%Pn; after the voltage returns to normal, the output power should be the output power corresponding to the actual wind conditions; Dynamic reactive power support capability: When a three-phase symmetrical voltage rise occurs at the wind turbine grid connection point, the wind turbine should respond quickly from the moment the voltage rise occurs, and support voltage recovery by injecting inductive reactive current. The specific requirements are as follows:

[0066] The response time of dynamic inductive reactive current control is no more than 40ms from the moment the voltage rise occurs at the grid connection point, and the inductive reactive current is continuously injected during the voltage fault period;

[0067] The dynamic inductive reactive current provided by the wind turbine should meet the requirements of formula (2):

[0068] I TL ≥1.5×(U T -1.1)I n ,(1.1≤U T ≤1.3)…………(2)

[0069] When a three-phase asymmetric voltage rise occurs at the wind turbine grid connection point, the wind turbine should inject inductive reactive current to support voltage recovery.

[0070] Fault voltage cascading failure test requirements: When a low or high voltage cascading fault occurs, when the low voltage ride-through ends and the grid voltage recovers to above 0.9pu, the active power should be restored to the output corresponding to the actual wind conditions at a power change rate of at least 10% Pn / s. During the voltage rise period, the output power is maintained at the power recovery characteristic after the low voltage ride-through ends or the output power corresponding to the actual wind conditions.

[0071] Figure 4-Figure 5 Middle Z sr It is a current limiting impedance used to limit the impact of the fault voltage on the power grid and other operating units in the wind farm. Before and after the voltage fault occurs, the current limiting impedance can be short-circuited using the bypass switch CB1.

[0072] As described in step S2, Figure 4-Figure 5 Middle Z sc To short-circuit the impedance, close the short-circuit switch CB2 and connect the three or two phases of the short-circuit impedance together to generate the voltage drop required by the test at the test point.

[0073] Figure 4-Figure 5 Middle C L is the boost branch capacitor, R dFor the boost branch resistor, close the short-circuit switch CB3, and connect the three-phase or two-phase boost resistor and capacitor together to generate the required voltage increase at the test point.

[0074] When testing with a voltage fault generator, the allowable errors of the voltage drop and voltage rise are shown in Figure 6-Figure 7 The short-circuit switches CB2 and CB3 should be able to accurately control the input and output time of the short-circuit impedance and the boost resistor and capacitor in all three-phase or two-phase circuits, and the voltage drop and voltage rise should be within Figure 6-Figure 7 The X / R of the current limiting impedance and the short-circuit impedance should be greater than 10.

[0075] Taking high voltage ride through as an example, the specific test steps are as follows: Figure 8 As shown, Figure 8 T1 is the fan box transformer with a voltage level of 35KV / 690V. The access point is connected to the low-voltage side of the fan box transformer and is used to connect the fault ride-through test container to the main power supply circuit of the fan. The test point is connected to the current transformer and the voltage transformer to collect the grid voltage and current during the high voltage ride-through process, which is used to assess the high voltage ride-through capability of the fan.

[0076] Figure 8 The dotted box shows the topology of the mobile high voltage ride through test equipment, where X1 is the current limiting reactance, X2 is the boosting capacitive reactance, K1 is the current limiting reactance group circuit breaker, K2 is the short-circuit reactance group circuit breaker, and K3 is the abnormal protection circuit breaker. The reactance group X1 is used to limit the impact of voltage increase on the power grid and other wind turbines in operation in the wind farm, and the reactance group X2 can achieve voltage increases of different amplitudes.

[0077] The basic principle of increasing the voltage at the test point is capacitive reactive injection. When the current limiting reactance group X1 is put into operation, the reactive capacitor is put into operation in the primary system by closing the short-circuit capacitive reactance group circuit breaker K2. The capacitive current I generated by the reactive capacitor X2 c The current flows from the test point through the current limiting reactor X1 to the system access point, thereby generating a voltage difference across the current limiting reactor X1: ΔU. Since the test system access point is the system voltage, it remains basically unchanged, thereby increasing the voltage Ut at the test point. In terms of value, Ut = Un + ΔU. By adjusting the input impedance value of the current limiting reactor X1 and the reactive capacitor X2, the amplitude of the voltage increase at the test point can be changed, and the adjustment step can be arbitrarily adjusted according to the adjustment step of the impedance value. The duration of the voltage increase can be arbitrarily set by adjusting the closing duration of the short-circuit capacitance group circuit breaker K2.

[0078] As described in step S3, Figure 2As shown, the timing of grid voltage drop simulation is as follows: in the initial state, K1 is closed and K2 is disconnected. After the test starts, the K1 circuit breaker is disconnected, and the current limiting reactor group is connected in series to the circuit. After 5ms, the K2 circuit breaker is closed, and the three-phase or two-phase branch composed of the boost impedance and the boost damping resistor is connected together to generate the required voltage rise at the test point.

[0079] The low voltage topology diagram is similar to the high voltage one, except that the fault generating device is changed. In the initial state, K1 is closed and K3 is disconnected. After the test starts, the K1 circuit breaker is disconnected and the current limiting reactor group is connected in series to the circuit. After 5ms, the K3 circuit breaker is closed and the three or two phases of the branch composed of the step-down inductive reactance are connected together to generate the required voltage reduction at the test point.

[0080] The control logic is as follows: when the unit is under-voltage riding, K1 is disconnected, K2 is energized, and K3 is disconnected; when the unit is under-voltage riding, K1 is disconnected, K2 is disconnected, and K3 is energized; when the unit is under-voltage riding continuously, K1 is energized first, K2 is disconnected, and K3 is disconnected; K1 is disconnected, K2 is energized, and K3 is disconnected; K1 is disconnected, K2 is disconnected, and K3 is energized; K1 is disconnected, K2 is disconnected, and K3 is energized; K1 is disconnected, K2 is energized, and K3 is disconnected; K1 is disconnected, K2 is disconnected, and K3 is energized; K1 is disconnected, K2 is energized, and K3 is disconnected; K1 is disconnected, K2 is disconnected, and K3 is energized; K1 is energized, K2 is disconnected, and K3 is disconnected.

[0081] like Fig. 9 The flowchart is shown as follows when the unit is continuously crossing high and low voltage. The voltage on the grid side of the unit is increased and decreased by controlling the equipment, thereby testing the high and low voltage performance of the unit. The simulation result of the equipment described in step S4 is as follows: Fig.10 As shown, by controlling the low and high changes of the grid-side voltage twice continuously, check whether the converter can work stably after the change and check the accuracy of the waveform.

[0082] In summary, the present invention constructs a high and low penetration detection model, artificially triggers the rise or fall of the power grid within a certain period of time through a fault trigger device, collects relevant data to verify the high and low penetration capabilities of the unit, and tests the high and low penetration capabilities of the unit through detection equipment, thereby reducing the impact of such faults on power generation, maintaining the safety of workers, and improving the power generation capacity of the wind turbine.

[0083] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A detection device suitable for high and low wear performance, characterized in that: It includes an inverter, an IO board, a high-throughput generating device, a low-throughput generating device, a CAN communication module, and a host computer. The branch connecting the power grid and the inverter is connected with a parallel contactor switch. The high-throughput generating device and the low-throughput generating device are connected to the branch. The IO board is connected to the contactor switch, the high-throughput generating device, and the low-throughput generating device. The inverter is connected to the host computer through the CAN communication module.

2. The high and low wear performance detection device according to claim 1, characterized in that: The IO board provides 24V power to the test equipment through a DC analog power supply.

3. The high and low wear performance detection device according to claim 1, characterized in that: The IO board includes an analog signal module, the analog signal module includes a plurality of analog output terminals, and each of the analog output terminals outputs a related switch signal corresponding to a device.

4. The high and low wear performance detection device according to claim 3, characterized in that: The analog signal module includes a plurality of analog input terminals, and the output of each analog input terminal corresponds to a related enabling state of a device.

5. The high and low wear performance detection device according to claim 1, characterized in that: The CAN communication module is a CAN communication to Ethernet module.

6. A control method for high and low wear performance detection equipment, characterized in that: The steps include: Step S1: Analyze the requirements for high and low wear and determine the relevant parameters; Step S2: Determine the connection of relevant circuit structures and construct a high and low voltage trigger circuit based on capacitors and inductors; Step S3: construct a device connection diagram and trigger high and low voltage ride-through through the IO control board; Step S4: Observe the relevant waveforms before and after the high and low voltage ride-through through the host computer.

7. The high and low wear performance detection device according to claim 6, characterized in that: In step S1, the low voltage ride-through requirement is: for wind turbines that are not disconnected from the grid during the voltage drop, the active power should be restored to the output power corresponding to the actual wind conditions at a power change rate of at least 10% Pn / s from the moment the voltage returns to normal; dynamic reactive power support capability: when a three-phase symmetrical voltage drop occurs at the grid connection point of the wind turbine, the wind turbine should respond quickly from the moment the voltage drop occurs, and support the voltage recovery by injecting capacitive reactive current; the specific requirements are as follows: The response time of dynamic capacitive reactive current control is no more than 75ms from the moment the voltage drop occurs at the grid connection point, and the capacitive reactive current is continuously injected during the voltage fault period; The dynamic capacitive reactive current provided by the wind turbine should meet the requirements of formula (1): I TC ≥1.5×(0.9-U T )I n ,(0.2≤U T ≤0.9)……………(1) When a three-phase asymmetric voltage drop occurs at the wind turbine grid connection point, the wind turbine should inject capacitive reactive current to support voltage recovery; The requirements for high voltage ride-through are as follows: Active power output: For wind turbines that are not disconnected from the grid, the active power fluctuation amplitude should be within the range of ±50% Pn at the time of voltage increase and the time of voltage recovery, and the fluctuation time should not exceed 80ms; during the voltage increase period, the output active power fluctuation amplitude should be within the range of ±5% Pn; after the voltage returns to normal, the output power should be the output power corresponding to the actual wind conditions; Dynamic reactive power support capability: When a three-phase symmetrical voltage increase occurs at the wind turbine grid connection point, the wind turbine should respond quickly from the moment the voltage increase occurs, and support voltage recovery by injecting inductive reactive current; The specific requirements are as follows: The response time of dynamic inductive reactive current control is no more than 40ms from the moment the voltage rise occurs at the grid connection point, and the inductive reactive current is continuously injected during the voltage fault period; The dynamic inductive reactive current provided by the wind turbine should meet the requirements of formula (2): I TL ≥1.5×(U T -1.1)I n ,(1.1≤U T ≤1.3)…………(2) When the three-phase asymmetric voltage rises at the wind turbine grid connection point, the wind turbine should inject inductive reactive current to support voltage recovery; Fault voltage cascading failure test requirements: When a low or high voltage cascading fault occurs, when the low voltage ride-through ends and the grid voltage recovers to above 0.9pu, the active power should be restored to the output corresponding to the actual wind conditions at a power change rate of at least 10% Pn / s. During the voltage rise period, the output power is maintained at the power recovery characteristic after the low voltage ride-through ends or the output power corresponding to the actual wind conditions.

8. The high and low wear performance detection device according to claim 7, characterized in that: In step S2, the current limiting impedance Z sr To limit the impact of fault voltage on the power grid and other operating units in the wind farm, the current limiting impedance is short-circuited using the bypass switch CB1 before and after the voltage fault occurs; Z sc To short-circuit the impedance, close the short-circuit switch CB2 and connect the three or two phases of the short-circuit impedance together to generate the voltage drop required by the test at the test point. C L is the boost branch capacitor, R d For the boost branch resistor, close the short-circuit switch CB3, and connect the three-phase or two-phase boost resistor and capacitor together to generate the required voltage increase at the test point.

9. The high and low wear performance detection device according to claim 8, characterized in that: As described in step S3, the grid voltage drop simulation timing is as follows: in the initial state, K1 is closed and K2 is disconnected. After the test starts, the K1 circuit breaker is disconnected, and the current limiting reactor group is connected in series to the loop. After 5ms, the K2 circuit breaker is closed, and the three phases or two phases of the branch composed of the boost impedance and the boost damping resistor are connected together to generate the required voltage increase at the test point; Low voltage topology: In the initial state, K1 is closed and K3 is disconnected. After the test starts, the K1 circuit breaker is disconnected, and the current limiting reactor group is connected in series to the circuit. After 5ms, the K3 circuit breaker is closed, and the three or two phases of the branch composed of the step-down inductive reactance are connected together to generate the required voltage reduction at the test point.

10. The high and low wear performance detection device according to claim 9, characterized in that: In step S4, by controlling the grid-side voltage to change between low and high twice in a row, it is checked whether the converter can work stably after the change and the accuracy of the waveform is checked.

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