Wind power converter low voltage ride through cooperative control method and system

Abstract

The invention relates to the field of low voltage ride-through control, and particularly discloses a wind power converter low voltage ride-through cooperative control method and system, which starts conventional LVRT response through a fault detection module, provides basic reactive power support and inhibits active power, and evaluates a power grid recovery state through a power grid recovery state evaluation module. Key indexes such as grid-connected point voltage recovery slope, frequency deviation and system short-circuit capacity are comprehensively analyzed, and a power grid recovery health degree index is quantitatively generated. Then, based on the index, a self-adaptive active power recovery slope is decided by combining local states such as a direct current bus voltage of the fan itself and the like. And finally, the active power recovery module smoothly recovers power output according to the adaptive slope. Through the mode, the power recovery behavior of the fan is tightly coupled with the real-time bearing capacity of the power grid, cooperative recovery control of low voltage ride through is realized, the stability of the power grid is ensured, and the efficiency and safety of power recovery are improved.

Description

Technical Field

[0001] This application relates to the field of low voltage ride-through control, and more specifically, to a method and system for coordinated low voltage ride-through control of wind power converters. Background Technology

[0002] With the increasing global demand for clean energy, the penetration rate of renewable energy, represented by wind power, in the power system is constantly improving. As an important distributed power source, the operational stability and grid-friendliness of wind turbines are crucial to the safety of the entire power system. However, the inherent intermittency and volatility of wind power, as well as faults such as short circuits and lightning strikes that may occur during power system operation, often lead to instantaneous voltage drops at the grid connection point of wind farms. According to the mandatory requirements of the grid guidelines, wind turbines must have low voltage ride-through (LVRT) capability, that is, to remain connected to the grid during grid voltage drops and provide dynamic reactive power support to the grid to help the grid voltage recover as quickly as possible.

[0003] After a voltage dip in the power grid, traditional LVRT (Low Voltage Reduction) control strategies typically employ a relatively fixed mode. Upon detecting a voltage dip, the wind turbine converter immediately switches to LVRT control mode, prioritizing reactive current injection to support the grid voltage while significantly suppressing active power output to prevent converter overcurrent. Once the grid voltage recovers above the normal threshold, active power is restored to pre-fault levels at a fixed, preset slope. However, this uniform recovery strategy has a significant problem: it ignores the actual recovery capability of the power grid under different fault scenarios and the operating status of the wind turbines themselves. Specifically, the strength of the power grid (e.g., system short-circuit capacity), the severity of the fault, and the cumulative effect of multiple turbines simultaneously restoring active power all affect secondary voltage stability. If the grid remains vulnerable, and all turbines restore active power at a relatively fast, fixed slope, a large surge in active power could cause the newly restored grid connection voltage to drop again, or even trigger a cascading grid disconnection, seriously threatening grid security. Conversely, if the grid has recovered well, an overly conservative recovery rate can affect the wind farm's power generation efficiency and the grid's frequency stability. Therefore, the strategy of using a fixed recovery slope in the existing technology lacks adaptability to the grid conditions and makes it difficult to achieve fast and efficient power recovery while ensuring safety.

[0004] Therefore, an optimized low-voltage ride-through coordinated control scheme for wind power converters is desired. Summary of the Invention

[0005] To address the aforementioned technical problems, this application is proposed. Embodiments of this application provide a low-voltage ride-through coordinated control method and system for wind power converters.

[0006] According to one aspect of this application, a low-voltage ride-through coordinated control method for a wind power converter is provided, comprising:

[0007] Fault detection and routine LVRT response are performed based on the grid voltage RMS value and grid guideline LVRT curve to obtain reactive current support reference value and suppressed active power command.

[0008] The power grid recovery status is assessed based on the PCC point voltage waveform, the real-time frequency of the PCC point, and the estimated system short-circuit capacity to obtain the power grid recovery health index.

[0009] Based on the power grid recovery health index, DC bus voltage, and maximum allowable recovery slope, a localized recovery slope decision for wind turbines is made to obtain an adaptive active power recovery slope.

[0010] Active power recovery is performed smoothly based on adaptive active power recovery slope, pre-fault active power and suppressed active power command to obtain active power reference value during the recovery process.

[0011] Based on the active power reference value, reactive current support reference value, dq-axis grid current feedback and dq-axis grid voltage feedback during the recovery process, a collaborative recovery command is generated to obtain a PWM pulse signal.

[0012] According to another aspect of this application, a low-voltage ride-through coordinated control system for a wind power converter is provided, comprising:

[0013] The LVRT conventional response analysis module is used to perform fault detection and LVRT conventional response based on the grid voltage RMS value and grid guide LVRT curve to obtain the reactive current support reference value and the suppressed active power command.

[0014] The power grid recovery status assessment module is used to assess the power grid recovery status based on the PCC point voltage waveform, the real-time frequency of the PCC point, and the estimated system short-circuit capacity to obtain the power grid recovery health index.

[0015] The wind turbine localized recovery decision module is used to make localized recovery slope decisions for wind turbines based on the grid recovery health index, DC bus voltage and maximum allowable recovery slope to obtain an adaptive active power recovery slope;

[0016] The active power recovery module is used to smoothly generate active power recovery execution based on the adaptive active power recovery slope, the active power before the fault, and the suppressed active power command to obtain the active power reference value during the recovery process.

[0017] The recovery instruction generation module is used to generate collaborative recovery instructions based on the active power reference value, reactive current support reference value, dq-axis grid current feedback and dq-axis grid voltage feedback during the recovery process to obtain PWM pulse signals.

[0018] Compared with existing technologies, this application provides a low-voltage ride-through (LVRT) collaborative control method and system for wind power converters. It initiates a conventional LVRT response through a fault detection module, providing basic reactive power support and suppressing active power. A grid recovery status assessment module comprehensively analyzes key indicators such as the grid connection point voltage recovery slope, frequency deviation, and system short-circuit capacity to quantify and generate a grid recovery health index. Then, based on this index and combined with local conditions such as the wind turbine's DC bus voltage, an adaptive active power recovery slope is determined. Finally, the active power recovery module smoothly restores power output according to this adaptive slope. In this way, the wind turbine's power recovery behavior is tightly coupled with the grid's real-time withstand capability, achieving collaborative recovery control of low-voltage ride-through, ensuring grid stability while improving the efficiency and safety of power recovery. Attached Figure Description

[0019] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0020] Figure 1 This is a flowchart of a wind power converter low voltage ride-through coordinated control method according to an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of data flow in the low-voltage ride-through cooperative control method for wind power converters according to an embodiment of this application;

[0022] Figure 3 This is a flowchart illustrating the low-voltage ride-through coordinated control method for wind power converters according to embodiments of this application. It describes the process of fault detection and conventional LVRT response based on the grid voltage RMS value and grid guideline LVRT curve to obtain reactive current support reference value and suppressed active power command.

[0023] Figure 4 This is a flowchart illustrating the process of generating a smooth active power recovery execution based on an adaptive active power recovery slope, pre-fault active power, and suppressed active power commands to obtain an active power reference value during the recovery process, according to the wind power converter low voltage ride-through coordinated control method of this application embodiment.

[0024] Figure 5 This is a block diagram of a wind power converter low voltage ride-through cooperative control system according to an embodiment of this application. Detailed Implementation

[0025] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0026] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0027] While this application makes various references to certain modules of the systems according to embodiments of this application, any number of different modules can be used and run on user terminals and / or servers. The modules described are merely illustrative, and different aspects of the systems and methods may use different modules.

[0028] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously as needed. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0029] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0030] To address the technical problem of existing wind turbine converters using a fixed slope to restore active power after low voltage ride-through (LVRT), which can lead to secondary voltage dips or even grid disconnection due to their inability to adapt to real-time grid recovery, this application proposes a collaborative control method for low voltage ride-through in wind turbine converters. This method aims to establish a dynamic feedback and coordination mechanism between the wind turbine and the grid. Specifically: First, when the system detects a voltage dip at the grid connection point and triggers LVRT, the control system immediately executes a conventional response, accurately generating reactive current to support the grid based on grid guidelines and the voltage dip depth, while simultaneously suppressing active power to the minimum level to ensure the safe operation of the converter. Subsequently, the grid recovery status assessment stage begins, continuously monitoring multiple key parameters such as the voltage waveform at the grid connection point, real-time frequency, and system short-circuit capacity. By weighted and fused calculations of these multi-dimensional information, a quantitative grid recovery health index is generated in real time, which intuitively reflects the current vulnerability and resilience of the grid. Next, the wind turbine's local controller uses this health index as a key input, combining it with its own DC bus voltage stability and a preset maximum allowable recovery slope, to make localized recovery decisions and dynamically calculate an optimal adaptive active power recovery slope. Finally, based on this adaptive slope, the system smoothly increases the active power reference value until it returns to the pre-fault level. In this way, this solution transforms the wind turbine's power recovery behavior from a fixed, blind mode to an intelligent mode that coordinates with the grid's status. This ensures gentle recovery to avoid impact when the grid is vulnerable, and rapid recovery to improve efficiency when the grid is strong, thus fundamentally solving the grid stability problem caused by inappropriate recovery strategies.

[0031] The technical solution of this application proposes a low-voltage ride-through collaborative control method for wind power converters. Figure 1 This is a flowchart of a wind power converter low voltage ride-through coordinated control method according to an embodiment of this application. Figure 2 This is a schematic diagram of the data flow in the low-voltage ride-through coordinated control method for wind power converters according to an embodiment of this application. Figure 1 and Figure 2As shown, the wind power converter low voltage ride-through coordinated control method according to an embodiment of this application includes the following steps: S100, performing fault detection and LVRT conventional response based on the grid voltage RMS value and grid guideline LVRT curve to obtain reactive current support reference value and suppressed active power command; S200, performing grid recovery status assessment based on PCC point voltage waveform, PCC point real-time frequency and estimated system short-circuit capacity to obtain grid recovery health index; S300, performing wind turbine localized recovery slope decision based on grid recovery health index, DC bus voltage and maximum allowable recovery slope to obtain adaptive active power recovery slope; S400, performing active power recovery execution smoothing generation based on adaptive active power recovery slope, pre-fault active power and suppressed active power command to obtain active power reference value during recovery process; S500, performing coordinated recovery command generation based on active power reference value during recovery process, reactive current support reference value, dq-axis grid current feedback and dq-axis grid voltage feedback to obtain PWM pulse signal.

[0032] Specifically, in step S100, fault detection and routine LVRT response are performed based on the grid voltage RMS value and the grid guideline LVRT curve to obtain the reactive current support reference value and the suppressed active power command. It should be understood that since wind turbine grid-connected operation must comply with the local grid guidelines, these guidelines clearly stipulate the obligation of generating equipment to maintain grid-connected operation and provide dynamic voltage support during grid voltage dips, i.e., low voltage ride-through (LVRT) requirements. If the wind turbine cannot respond to grid faults in a timely and accurate manner, it will not only disconnect from the grid due to its own protection, causing power generation loss, but may also exacerbate grid voltage collapse and trigger large-scale blackouts. Therefore, in the technical solution of this application, fault detection and routine LVRT response are performed based on the grid voltage RMS value and the grid guideline LVRT curve to ensure that the wind power converter can strictly follow grid connection specifications and initiate standardized LVRT actions at the first moment of a fault. This lays a compliant and reliable foundation for subsequent coordinated recovery control, ensuring the legality and effectiveness of the entire control strategy, fulfilling the responsibility of supporting the grid, and improving the grid friendliness of the system.

[0033] Figure 3 This is a flowchart illustrating the low-voltage ride-through (LVRT) coordinated control method for wind power converters according to embodiments of this application. It describes fault detection and conventional LVRT response based on the grid voltage RMS value and grid guidance LVRT curve to obtain reactive current support reference values ​​and suppressed active power commands. Figure 3As shown, step S100 includes: S110, extracting the LVRT voltage threshold from the grid guideline LVRT curve; S120, comparing the effective value of the grid voltage with the LVRT voltage threshold; S130, if the effective value of the grid voltage is less than the LVRT voltage threshold, setting the low-voltage-breakdown status flag to true and calculating the voltage sag depth, the voltage sag depth being equal to a quotient of the effective value of the grid voltage divided by the rated voltage; S140, if the effective value of the grid voltage is greater than or equal to the LVRT voltage threshold, setting the low-voltage-breakdown status flag to false and setting the voltage sag depth to zero; S150, generating a reactive current support reference value and a suppressed active power command based on the voltage sag depth.

[0034] More specifically, the implementation process of this fault detection and LVRT routine response is as follows: First, extract key parameters from the LVRT curve of the grid guidelines. The control system pre-configures or reads the applicable grid guidelines for the grid connection point online, and parses the voltage threshold defined by the LVRT curve. For example, when the voltage is lower than 90% of the rated voltage, an LVRT response needs to be initiated; the voltage value corresponding to 90% is the LVRT voltage threshold. Second, perform real-time fault judgment. The control system continuously collects the three-phase voltage waveforms of the grid connection point through voltage sensors and calculates its effective grid voltage value. Subsequently, it compares this real-time effective grid voltage value with the LVRT voltage threshold extracted in the first step. Third, activate the LVRT state and quantify the fault severity. If the comparison result shows that the effective grid voltage value is less than the LVRT voltage threshold, the system determines that the grid has entered a fault state and immediately sets a low-voltage status flag to true in the control logic. Simultaneously, to accurately control the subsequent support strength, the system immediately calculates the voltage drop depth, which is calculated by subtracting the quotient of the current effective grid voltage value and the rated voltage. Conversely, if the effective value of the grid voltage is greater than or equal to the LVRT voltage threshold, the low-voltage sag flag will be set to false and the voltage drop depth will be cleared to zero, indicating that the system is in normal operating condition.

[0035] The fourth step is to generate initial response commands. With the low-voltage dip flag true, the system generates two core initial control commands based on the voltage dip depth calculated in the previous step: The first is a reactive current support reference value, which is positively correlated with the voltage dip depth; the deeper the voltage dip, the greater the reactive current support required to strongly support grid voltage recovery. The second is a suppressed active power command. The system will forcibly set the active power command to an extremely low value, such as 5% of the rated power, to reduce the current stress on the converter, prevent overcurrent damage due to high active power output at low voltage, and prioritize the converter's capacity for reactive power support. These two commands will serve as the initial targets for the converter's inner-loop control, initiating the LVRT's normal response.

[0036] Specifically, in this embodiment of the application, based on the voltage sag depth, generating a reactive current support reference value and a suppressed active power command includes:

[0037] Based on the voltage drop depth, the reactive current support reference value is calculated using the following formula:

[0038] Q ref-s =k Q *V drop-d *I nom ;

[0039] Among them, V drop-d I represents the voltage sag depth. nom For the rated current and k Q Q is the reactive power support factor. ref-s This is a reference value for reactive current support.

[0040] The minimum sustaining active power is assigned to the suppressed active power command, wherein the minimum sustaining active power is 5% of the rated power.

[0041] Specifically, in step S200, a grid recovery status assessment is performed based on the PCC point voltage waveform, the PCC point real-time frequency, and the estimated system short-circuit capacity to obtain a grid recovery health index. It should be understood that the grid recovery process after fault clearance is a complex and dynamic process, and its recovery capability is affected by various factors such as the grid's own strength, the severity of the fault, and the clearance time, exhibiting significant uncertainty. If wind turbines restore active power at a uniform rate simply based on whether the voltage exceeds a certain fixed threshold after LVRT, it is highly likely to cause secondary disturbances due to misjudging the true health status of the grid. For example, injecting a large amount of active power into a still vulnerable grid will directly cause the voltage to drop again. Therefore, in the technical solution of this application, a grid recovery status assessment is further performed based on the PCC point voltage waveform, the PCC point real-time frequency, and the estimated system short-circuit capacity to comprehensively and dynamically quantify the grid's health status during the recovery period. This provides an accurate and reliable basis for subsequent active power recovery decisions, avoiding the blindness of traditional fixed recovery strategies, thereby improving the collaborative adaptability between wind turbines and the grid.

[0042] More specifically, in this embodiment of the application, the power grid recovery status assessment based on the PCC point voltage waveform, the real-time frequency of the PCC point, and the estimated system short-circuit capacity to obtain the power grid recovery health index includes: performing linear fitting on the PCC point voltage waveform to obtain the voltage recovery slope; calculating the deviation between the real-time frequency of the PCC point and the fixed frequency to obtain the frequency deviation; and calculating the power grid recovery health index based on the estimated system short-circuit capacity, the voltage recovery slope, and the frequency deviation.

[0043] Specifically, in a specific example of this application, calculating the power grid recovery health index based on the estimated system short-circuit capacity, voltage recovery slope, and frequency deviation includes: calculating the power grid recovery health index based on the estimated system short-circuit capacity, voltage recovery slope, and frequency deviation using the following formula:

[0044] GRHI = w1 * norm(V slope )+w2*(1-norm(f dev ))+w3*norm(SC cap-est );

[0045] Where norm(·) is the normalization function, w1, w2, and w3 are preset weights, and V slope f is the voltage recovery slope. dev For frequency deviation and SC cap-est This is the estimated system short-circuit capacity.

[0046] More specifically, the implementation process of power grid recovery status assessment is as follows: First, extract dynamic characteristics of voltage recovery. After detecting the start of voltage recovery in the grid, continuously collect the effective voltage value sequence at the grid connection point. By linearly fitting or calculating the first derivative of multiple voltage sampling points within a set time window (e.g., the most recent 100 milliseconds), a quantified voltage recovery slope is obtained. This slope intuitively reflects the speed and trend of voltage recovery and is one of the core dynamic indicators for assessing the power grid recovery status. Second, assess system frequency stability. Using a phase-locked loop or other frequency detection algorithm, calculate the grid frequency at the PCC point in real time. Subsequently, compare this real-time frequency with the grid's rated frequency (e.g., 50Hz or 60Hz) to calculate the frequency deviation between the two. The magnitude of the frequency deviation reflects the balance of active power in the system and is an important static indicator for measuring grid stability. Third, comprehensively assess grid strength. Since the system short-circuit capacity is a key parameter characterizing the strength of the grid, reflecting the grid's ability to withstand disturbances and maintain voltage stability, this parameter can be given offline, issued by the station's main control system, or estimated in real time through online identification algorithms. A higher short-circuit capacity value indicates a more robust power grid. The fourth step is to calculate the comprehensive health index. The system integrates information from the previous steps regarding the voltage recovery slope, frequency deviation, and estimated system short-circuit capacity. Using a weighted formula, such as normalizing the parameters and then performing a weighted sum, a single, comprehensive power grid recovery health index is calculated. This index comprehensively reflects the power grid's recovery status from dynamic, static, and structural strength perspectives, and is a value between 0 and 1. A higher value indicates a better and healthier power grid recovery.

[0047] Specifically, in step S300, a localized recovery slope decision for the wind turbine is made based on the grid recovery health index, DC bus voltage, and maximum allowable recovery slope to obtain an adaptive active power recovery slope. It should be understood that relying solely on the grid's health status to determine the active power recovery rate is insufficient; the wind turbine's own operating status, especially the stability of the DC bus voltage (which acts as an energy buffer), is also a key constraint determining its ability to output power smoothly. During rapid active power recovery, if the DC bus voltage fluctuates drastically or exceeds safety limits, it will directly threaten the safety of core components such as the converter. Therefore, in the technical solution of this application, a recovery slope decision mechanism integrating grid health and the wind turbine's local status is further established to ensure that the final active power recovery rate matches the grid's capacity while remaining within the safe operating boundaries of the wind turbine itself. This achieves a unification of global coordination and local constraints, making recovery decisions more accurate and safer, and avoiding the risk of equipment damage or control instability due to ignoring the wind turbine's own status.

[0048] More specifically, in this embodiment of the application, the localized recovery slope decision for wind turbines based on the grid recovery health index, DC bus voltage, and maximum allowable recovery slope to obtain an adaptive active power recovery slope includes: multiplying the grid recovery health index by the maximum allowable recovery slope to obtain a basic active power recovery slope; calculating a local correction factor based on the DC bus voltage; and multiplying the local correction factor by the basic active power recovery slope to obtain the adaptive active power recovery slope.

[0049] Specifically, the process of determining the localized recovery slope for wind turbines includes the following steps: First, multiply the grid recovery health index (a value between 0 and 1) calculated in the previous stage by a preset maximum allowable recovery slope representing the fastest recovery rate that the equipment and grid can withstand. This maximum allowable recovery slope is a fixed upper limit determined based on factors such as converter design margin and mechanical transmission chain stress. The result of this multiplication is the basic active power recovery slope, which initially reflects the ideal power recovery rate under the current grid health condition. Second, monitor the voltage value of the DC bus inside the wind turbine converter in real time. Through a preset function or lookup table, the DC bus voltage is mapped to a local correction factor. The logic of this function is: when the DC bus voltage is stable near the rated value, the correction factor is 1, and no correction is performed; when the DC bus voltage deviates too high or too low, approaching the protection boundary, the correction factor will smoothly decrease to a value less than 1, or even approach 0. This correction factor quantifies the energy balance state of the wind turbine itself; the more unstable the voltage, the lower the willingness to correct. Specifically, the calculation of the local correction factor can be implemented using a trained deep neural network model. By utilizing a large number of DC bus voltage values ​​to construct a mapping relationship between them and the local correction factor, in practical applications, when a DC bus voltage value is input, the corresponding local correction factor is output. The third step multiplies the basic active power recovery slope obtained in the first step with the local correction factor calculated in the second step. This product is the final output adaptive active power recovery slope. Through this step, the recovery state of the power grid and the operating state of the wind turbine are coupled together, jointly determining the final recovery rate. For example, even if the power grid recovery health index is high (1), if the DC bus voltage is unstable, resulting in a correction factor of 0.5, the final recovery slope will only be limited to half of the maximum allowable slope, thus prioritizing the safety of the wind turbine itself. This adaptive active power recovery slope will directly guide the next step of the active power smoothing recovery process.

[0050] In step S400, active power recovery is smoothly generated based on the adaptive active power recovery slope, pre-fault active power, and suppressed active power command to obtain a reference value of active power during the recovery process. It should be understood that because the active power of wind turbines is significantly suppressed during low-voltage ride-through, if the active power recovery process is not smooth or the recovery rate is inappropriate after the grid voltage recovers, it may cause new shocks to the grid, triggering secondary fluctuations in voltage or frequency, or even leading to instability in the DC bus voltage inside the converter. Therefore, in the technical solution of this application, active power recovery is further smoothly generated based on the adaptive active power recovery slope, pre-fault active power, and suppressed active power command to ensure that active power can be gradually restored at a controlled rate that adapts to the grid and the wind turbine's own state. This effectively avoids the impact of power surges on the grid and wind turbine, ensures the stability and safety of system operation, and ultimately achieves efficient and stable power output.

[0051] Figure 4 This is a flowchart illustrating the active power recovery execution smoothing process based on adaptive active power recovery slope, pre-fault active power, and suppressed active power commands to obtain active power reference values ​​during the recovery process, according to the wind power converter low-voltage ride-through coordinated control method of this application. Figure 4 As shown, step S400 includes: S410, setting the initial value of the active power reference value during the recovery process to the suppressed active power command; S420, calculating the elapsed time based on the current time and the recovery start timestamp; S430, performing an unlimited ramp update on the active power reference value during the recovery process based on the elapsed time to obtain an unlimited update value for the active power reference value during the recovery process; S440, taking the smaller value between the unlimited update value of the active power reference value during the recovery process and the active power before the fault as the update value of the active power reference value during the recovery process.

[0052] Step S410: The initial value of the active power reference value during the recovery process is set to the suppressed active power command. It should be understood that during low voltage ride-through (LVRT), the active power output of the wind power converter is forcibly suppressed to an extremely low level—the suppressed active power command—in order to prioritize providing reactive power support to stabilize the grid voltage and protect itself from overcurrent. When the grid voltage begins to recover, and the converter prepares to exit LVRT and gradually restore active power output, if a reasonable starting point is not clearly set, directly starting the recovery from zero or an uncertain value may lead to abrupt changes in the power command, resulting in severe fluctuations in the DC bus voltage and even impacting the converter. Therefore, in the technical solution of this application, the initial value of the active power reference value during the recovery process is further explicitly set to the suppressed active power command to ensure that the active power recovery process starts smoothly from a known and safe low power point. This effectively avoids transient impacts in the initial stage of power recovery, ensures a smooth transition for the converter and the grid, and lays a solid foundation for subsequent adaptive slope recovery.

[0053] In a specific example of this application, the initial value setting is implemented as follows: When the wind power converter transitions from the low voltage ride-through (LVRT) state to the active power recovery (AVR) stage, the control system first acquires the active power command value that was forcibly suppressed during LVRT. This value is typically a preset minimum sustaining power, such as 5% of the rated power, representing the minimum active power that the converter must output to maintain its operation during a fault. Subsequently, in the first control cycle after the recovery logic is initiated, the control algorithm directly assigns the suppressed active power command to the variable used for subsequent power recovery calculations—the active power reference value during the recovery process. This assignment operation ensures that the active power recovery does not start from zero, but from a known minimum power point that the converter continuously outputs during LVRT, thus achieving a seamless transition from the suppressed state to the recovery state, avoiding jumps in the power command, and providing a stable starting point for subsequent smooth ramp recovery.

[0054] Step S420: Calculate the elapsed time based on the current time and the recovery start timestamp. It should be understood that active power recovery is a dynamic process requiring a smooth transition, and its recovery amount is positively correlated with the recovery duration; that is, the power increase is based on a ramp function that grows linearly with time. Without precise measurement of the elapsed recovery time, it is impossible to accurately calculate the power reference value to be reached at the current moment according to the preset adaptive slope, leading to uncontrolled or uneven power recovery. Therefore, in the technical solution of this application, the elapsed time is further calculated based on the current time and the recovery start timestamp to provide an accurate time reference for the smooth ramp recovery of active power. This ensures that the active power recovery trajectory strictly follows the set adaptive slope, achieving continuous and stable power output growth and avoiding power jumps or untimely recovery caused by inaccurate time calculations.

[0055] In a specific example of this application, the calculation of the elapsed time is implemented as follows: When the wind power converter exits the low-voltage ride-through state and begins to execute the active power recovery strategy, the start time of this recovery process is recorded and used as the recovery start timestamp. This timestamp is typically derived from a high-precision clock or timer within the system to ensure its accuracy. Subsequently, throughout the entire active power recovery period, the control system acquires the current system time in real time during each control cycle, i.e., the current time. By subtracting the pre-recorded recovery start timestamp from this current time, the system can accurately calculate the elapsed time since the start of the recovery process. This elapsed time is a continuously updated variable that serves as a time parameter in subsequent active power ramp calculations, ensuring that the power reference value increases smoothly and linearly over time according to the previously determined adaptive active power recovery ramp.

[0056] Step S430: Based on the elapsed time, the active power reference value during the recovery process is updated with an unlimited ramp to obtain an unlimited updated value of the active power reference value during the recovery process. It should be understood that active power recovery must be a smooth and controlled process to avoid impacting the power grid and the converter itself; simple step recovery or irregular power changes may cause system instability. Therefore, in the technical solution of this application, the active power reference value during the recovery process is further updated with an unlimited ramp based on the elapsed time to ensure that the active power can gradually increase in a linear and continuous manner according to the previously determined adaptive slope. This provides a dynamic and smooth power growth trajectory, laying a solid foundation for subsequent power output command generation, effectively avoiding the negative impact of power abrupt changes, and ensuring the stability and security of system operation.

[0057] In a specific example of this application, the implementation process of the unrestricted slope update is as follows: Within each control cycle, the system acquires the elapsed time at the current moment and the adaptive active power recovery slope previously obtained based on the comprehensive decision-making process considering grid health and the local state of the wind turbine. Subsequently, the system uses the initial value of the active power reference value during the recovery process (i.e., the suppressed active power command) as the starting point, and adds the product of the adaptive active power recovery slope and the elapsed time to this initial value. This calculation result is the unrestricted update value of the active power reference value during the recovery process. This value represents the theoretically achievable active power level at the current elapsed time point if the power recovery process were not subject to any upper limit constraint. For example, if the initial power is P... min If the adaptive slope is K and the elapsed time is t, then the value P is updated without restriction. unlimited =P min +K*t. The core of this step is to construct a linear ramp function so that the active power reference value increases continuously and smoothly over time at a dynamically adjusted rate, providing a continuously changing theoretical target value for subsequent power output.

[0058] Step S440: The smaller of the unlimited update value of the active power reference value during the recovery process and the active power before the fault is taken as the update value of the active power reference value during the recovery process. It should be understood that the unlimited update value of the active power reference value during the recovery process calculated in the previous step is a value derived based on the slope function theory. It only reflects the linear growth trend of power over time and does not consider the actual active power output level of the wind turbine before the fault. Without restriction, this theoretical value may exceed the maximum active power that the wind turbine could actually output before the fault in the later stages of recovery. This not only does not conform to physical reality but may also lead to unreasonable power commands issued by the control system, causing problems such as converter overload or DC bus voltage instability. Therefore, in the technical solution of this application, the smaller of the unlimited update value of the active power reference value during the recovery process and the active power before the fault is further taken as the update value of the active power reference value during the recovery process. This ensures that the active power recovery process can smoothly and accurately converge to the actual operating point before the fault, avoiding power overshoot and unnecessary fluctuations. This ensures the stable operation of wind turbines during the recovery period and achieves effective power balance with the power grid.

[0059] Step S500 involves generating a PWM pulse signal based on the active power reference value, reactive current support reference value, dq-axis grid current feedback, and dq-axis grid voltage feedback during the recovery process, and executing a coordinated recovery command. It should be understood that, as a key power electronic device connecting the wind turbine and the grid, the core function of the wind power converter is to efficiently and accurately convert DC power into AC power that meets grid requirements, and to achieve independent control of active and reactive power. The aforementioned steps have generated refined active power and reactive current reference values, but these are still high-level control commands and cannot directly drive the converter's semiconductor switching devices. Without a mechanism to convert these commands into actual physical control signals, all complex control strategies will fail to be implemented, causing the wind turbine to be unable to respond to grid demands or perform self-protection. Therefore, in the technical solution of this application, a PWM pulse signal is further generated based on the active power reference value, reactive current support reference value, and dq-axis grid current and voltage feedback during the recovery process, thereby converting abstract power and current commands into specific switching actions and achieving precise control of the converter output. This ensures that wind turbines can respond to grid conditions and their own control strategies in real time and accurately, efficiently providing active and reactive power support, thereby guaranteeing the stable operation of the grid and the reliable grid connection of wind turbines.

[0060] Specifically, in this embodiment, a PWM pulse signal is generated by executing a coordinated recovery command based on the active power reference value, reactive current support reference value, dq-axis grid current feedback, and dq-axis grid voltage feedback during the recovery process. This includes: the outer loop controller of the converter calculating the dq-axis current reference value based on the active power reference value, reactive current support reference value, and dq-axis grid voltage feedback during the recovery process; the inner current loop comparing the dq-axis grid current feedback and the dq-axis current reference value using a PI controller to obtain the dq-axis voltage compensation amount; and performing coordinate inverse transformation and space vector modulation on the dq-axis voltage compensation amount to obtain the PWM pulse signal.

[0061] More specifically, the converter's outer loop controller calculates the dq-axis current reference value based on the active power reference value, reactive current support reference value, and dq-axis grid voltage feedback during the recovery process. It should be understood that the inner loop control of a wind power converter is typically current-based, indirectly controlling the output of active and reactive power by precisely controlling the dq-axis current. However, the commands generated by the upper-level control strategy are power or reactive current reference values, which cannot directly drive the converter's inner current loop. Without a mechanism to convert these power / reactive current commands into dq-axis current reference values, the converter will be unable to understand and execute the upper-level control intent, leading to a break in the entire control chain. Therefore, in the technical solution of this application, the process of calculating the dq-axis current reference value based on the active power reference value, reactive current support reference value, and dq-axis grid voltage feedback during the recovery process by the converter's outer loop controller is further implemented to convert the higher-level power / reactive current commands into current commands that the converter's inner loop can directly track. This enables independent and precise control of active and reactive power, ensuring that the converter can output the required power according to system requirements, thereby effectively supporting the power grid and achieving smooth power recovery.

[0062] In a specific example of this application, the calculation process for the dq-axis current reference value is as follows: The converter's outer loop controller receives two key inputs: one is the active power reference value from the active power recovery process of the active power recovery strategy, and the other is the reactive current support reference value from the LVRT conventional response. Simultaneously, the controller also acquires the dq-axis grid voltage feedback at the grid connection point in real time; this voltage feedback is a necessary parameter for power-to-current conversion. First, regarding the generation of the reactive current reference value, since the q-axis current mainly controls reactive power in the synchronously rotating dq coordinate system, the outer loop controller directly uses the reactive current support reference value as the reference value for the q-axis current. Second, for the conversion from the active power reference value to the d-axis current reference value, the outer loop controller uses the relationship between power, current, and voltage for calculation. In a three-phase system, the relationship between active power P and dq-axis voltage and current is P = 1.5 * (U d *I d +U q *I q ), where U d I is the d-axis voltage. d U is the d-axis current. q I is the q-axis voltage. q Let U be the q-axis current. In typical grid voltage-oriented control strategies, the d-axis is aligned with the grid voltage vector direction, such that the q-axis voltage U... q It is approximately zero. Therefore, the expression for active power simplifies to P≈1.5*U d *I dBased on this relationship, the outer loop controller divides the active power reference value during the recovery process by 1.5 times the d-axis grid voltage feedback to calculate the reference value of the d-axis current, i.e., I. d_ref =P ref / 1.5*U d_fb , among which, U d_fb For d-axis grid voltage feedback, P ref I is the active power reference value. d_ref This serves as the reference value for the d-axis current. Through the above calculations, the outer loop controller accurately converts the power and reactive current commands from the upper-level control strategy into dq-axis current reference values. These generated dq-axis current reference values ​​are then sent to the converter's inner current loop controller as its tracking target, thereby driving the converter to output the required active power and reactive current.

[0063] More specifically, the inner current loop uses a PI controller to compare the dq-axis grid current feedback and the dq-axis current reference value to obtain the dq-axis voltage compensation. It should be understood that while the converter's outer loop controller has generated accurate dq-axis current reference values, these reference values ​​are merely control targets and do not guarantee that the actual output current of the converter will accurately track these targets. Various disturbances on the grid side, uncertainties in system parameters, and the non-ideal characteristics of power electronic devices can all lead to deviations between the actual output current and the reference value. Without effective closed-loop correction of this deviation, precise control of active and reactive power cannot be achieved, rendering all upper-level optimization strategies ineffective. Therefore, in the technical solution of this application, the inner current loop uses a PI controller to compare the dq-axis grid current feedback and the dq-axis current reference value to obtain the dq-axis voltage compensation, thereby constructing a fast and robust current closed-loop feedback control system. This allows for the dynamic elimination of the error between the actual current and the reference current, ensuring that the converter can output the target current quickly and accurately. This enables precise decoupling control of active and reactive power, guaranteeing the system's high dynamic performance and steady-state accuracy.

[0064] In a specific example of this application, the implementation process of the current closed-loop control is as follows: The inner current controller is the core execution layer of the converter control system, and its operation is performed independently in the dq synchronous rotating coordinate system. First, the system collects the three-phase AC current at the grid connection point in real time and obtains the dq-axis grid current feedback through coordinate transformation. For the control of the d-axis current, the system compares the d-axis current reference value generated by the outer loop controller with the real-time d-axis grid current feedback and calculates the error between the two. This error signal is then sent to a d-axis PI controller. Based on the magnitude and duration of the error, the PI controller calculates a d-axis voltage compensation amount through its proportional and integral components. The function of this compensation amount is to adjust the d-axis component of the converter output voltage to drive the actual d-axis current to converge towards its reference value. Similarly, for the control of the q-axis current, the system compares the q-axis current reference value generated by the outer loop controller with the real-time q-axis grid current feedback to obtain the q-axis current error. This error signal is sent to another independent q-axis PI controller. The q-axis PI controller also calculates a q-axis voltage compensation based on the error, which is used to adjust the q-axis component of the converter output voltage, thereby precisely controlling the actual q-axis current. In this way, the d-axis and q-axis current control are decoupled and regulated in a closed loop by their respective independent PI controllers. The dq-axis voltage compensation outputs of the PI controllers are the necessary voltage adjustment signals to drive the actual current to track the reference current; they serve as a key component in generating the final modulated voltage command.

[0065] More specifically, the dq-axis voltage compensation quantity is subjected to inverse coordinate transformation and space vector modulation to obtain the PWM pulse signal. It should be understood that since the dq-axis voltage compensation quantity output by the aforementioned inner-loop PI controller is a DC signal in a synchronous rotating coordinate system, while the wind power converter itself is a three-phase AC physical system, its power electronic switching devices (such as IGBTs) need to be driven by three-phase AC voltage commands. If these control quantities in the dq coordinate system are not converted back to the actual three-phase AC domain and further used to generate pulse signals that can directly drive the switches, the entire control closed loop cannot be formed, and the control commands cannot be executed at the physical level. Therefore, in the technical solution of this application, the process of performing inverse coordinate transformation and space vector modulation on the dq-axis voltage compensation quantity to obtain the PWM pulse signal is further clarified, thereby completing the final conversion from abstract control commands to physical drive signals. In this way, the output of the control algorithm can be accurately mapped to the action of the converter switch, achieving accurate synthesis of the output voltage waveform, thereby ensuring that the converter can inject the required active and reactive current into the grid according to the requirements of the upper-level commands.

[0066] In a specific example of this application, the PWM pulse signal generation process is as follows: First, an inverse coordinate transformation is performed. The dq-axis voltage compensation amount calculated by the current inner-loop PI controller is obtained. To improve control performance, these compensation amounts are combined with the grid voltage feedforward and decoupling terms to form the final dq-axis modulated voltage command. Subsequently, the system performs an inverse Park transformation, converting the pair of dq-axis DC voltage commands in the synchronous rotating coordinate system back to the stationary three-phase abc coordinate system. This transformation requires the grid voltage phase angle information provided by the phase-locked loop to ensure that the generated AC voltage command is synchronized with the grid voltage. After the inverse Park transformation, a three-phase sinusoidal AC voltage reference signal is obtained. Second, space vector pulse width modulation (SVM) is performed. The three-phase AC voltage reference signal generated in the first step is input to the space vector pulse width modulation module. The space vector pulse width modulation algorithm first synthesizes the three voltage reference signals into a space voltage vector. Then, based on the position and magnitude of this space voltage vector in the hexagonal sector formed by the eight basic switching states of the converter, the algorithm calculates the action time of two adjacent basic voltage vectors and the zero vector to equivalently synthesize the target voltage vector. Finally, the space vector pulse width modulation module generates high-frequency PWM pulse signals corresponding to the six switching devices of the three-phase bridge arm of the converter based on the calculated action time. These PWM pulse signals have precise duty cycles and are directly sent to the drive circuit to control the on and off of switching devices such as IGBTs, thereby synthesizing the desired three-phase voltage waveform at the AC output of the converter and ultimately achieving precise control of the grid-connected current.

[0067] In summary, the low-voltage ride-through (LVRT) coordinated control method for wind power converters according to the embodiments of this application is explained. It initiates a conventional LVRT response through a fault detection module, providing basic reactive power support and suppressing active power. A grid recovery status assessment module comprehensively analyzes key indicators such as the grid connection point voltage recovery slope, frequency deviation, and system short-circuit capacity to quantify and generate a grid recovery health index. Then, based on this index and combined with local conditions such as the wind turbine's DC bus voltage, an adaptive active power recovery slope is determined. Finally, the active power recovery module smoothly restores power output according to this adaptive slope. In this way, the wind turbine's power recovery behavior is tightly coupled with the grid's real-time withstand capability, achieving coordinated recovery control of low-voltage ride-through, ensuring grid stability while improving the efficiency and safety of power recovery.

[0068] Furthermore, a low-voltage ride-through coordinated control system for wind power converters is also provided.

[0069] Figure 5 This is a block diagram of a wind power converter low-voltage ride-through coordinated control system according to an embodiment of this application. Figure 5As shown, the wind power converter low voltage ride-through coordinated control system 100 according to an embodiment of this application includes: an LVRT conventional response analysis module 110, used for fault detection and LVRT conventional response based on the grid voltage RMS value and grid guideline LVRT curve to obtain reactive current support reference value and suppressed active power command; a grid recovery status assessment module 120, used for grid recovery status assessment based on PCC point voltage waveform, PCC point real-time frequency and estimated system short-circuit capacity to obtain grid recovery health index; and a wind turbine localized recovery decision module 130, used for grid recovery... The system uses a health index, DC bus voltage, and maximum allowable recovery slope to determine the localized recovery slope of the wind turbine, thereby obtaining an adaptive active power recovery slope. An active power recovery module 140 is used to smoothly generate active power recovery commands based on the adaptive active power recovery slope, pre-fault active power, and suppressed active power commands, to obtain an active power reference value during the recovery process. A recovery command generation module 150 is used to generate coordinated recovery commands based on the active power reference value, reactive current support reference value, dq-axis grid current feedback, and dq-axis grid voltage feedback during the recovery process, to obtain a PWM pulse signal.

[0070] As described above, the wind power converter low-voltage ride-through cooperative control system 100 according to the embodiments of this application can be implemented in various wireless terminals, such as servers with wind power converter low-voltage ride-through cooperative control algorithms. In one possible implementation, the wind power converter low-voltage ride-through cooperative control system 100 according to the embodiments of this application can be integrated into the wireless terminal as a software module and / or hardware module. For example, the wind power converter low-voltage ride-through cooperative control system 100 can be a software module in the operating system of the wireless terminal, or it can be an application developed for the wireless terminal; of course, the wind power converter low-voltage ride-through cooperative control system 100 can also be one of many hardware modules of the wireless terminal.

[0071] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for low voltage ride through coordinated control of a wind power converter, characterized in that, The method comprises: detecting a fault and performing a LVRT regular response based on a grid voltage effective value and a grid guide LVRT curve to obtain a reactive current support reference value and a suppressed active power instruction; evaluating a grid recovery state based on a PCC point voltage waveform, a PCC point real-time frequency and an estimated system short-circuit capacity to obtain a grid recovery health index; making a wind turbine localized recovery slope decision based on the grid recovery health index, a DC bus voltage and a maximum allowed recovery slope to obtain an adaptive active power recovery slope; generating a smooth active power recovery execution based on the adaptive active power recovery slope, a pre-fault active power and the suppressed active power instruction to obtain an active power reference value in a recovery process; generating an execution cooperative recovery instruction based on the active power reference value in the recovery process, the reactive current support reference value, d-q axis grid current feedback and d-q axis grid voltage feedback to obtain a PWM pulse signal.

2. The wind power converter low voltage ride through coordinated control method according to claim 1, characterized in that, The method of detecting a fault and performing a LVRT regular response based on a grid voltage effective value and a grid guide LVRT curve to obtain a reactive current support reference value and a suppressed active power instruction comprises: extracting an LVRT voltage threshold from the grid guide LVRT curve; comparing the grid voltage effective value with the LVRT voltage threshold; if the grid voltage effective value is less than the LVRT voltage threshold, setting a low penetration state flag to true and calculating a voltage drop depth, the voltage drop depth being equal to one minus a quotient of the grid voltage effective value divided by a rated voltage; if the grid voltage effective value is greater than or equal to the LVRT voltage threshold, setting the low penetration state flag to false and setting the voltage drop depth to zero; generating the reactive current support reference value and the suppressed active power instruction based on the voltage drop depth.

3. The wind power converter low voltage ride through coordinated control method according to claim 2, characterized in that, The method of generating the reactive current support reference value and the suppressed active power instruction based on the voltage drop depth comprises: calculating the reactive current support reference value based on the voltage drop depth with a formula as follows: Q ref-s = k Q *V drop-d I nom ; where V drop-d is the voltage dip depth, I nom is the rated current and k Q is the reactive support factor; assigning a minimum maintained active power to the suppressed active power instruction, the minimum maintained active power being 5% of a rated power.

4. The wind power converter low voltage ride through coordinated control method according to claim 1, characterized in that, The method of evaluating a grid recovery state based on a PCC point voltage waveform, a PCC point real-time frequency and an estimated system short-circuit capacity to obtain a grid recovery health index comprises: performing a linear fitting on the PCC point voltage waveform to obtain a voltage recovery slope; calculating a deviation between the PCC point real-time frequency and a fixed frequency to obtain a frequency deviation; calculating the grid recovery health index based on the estimated system short-circuit capacity, the voltage recovery slope and the frequency deviation.

5. The wind power converter low voltage ride through coordinated control method according to claim 4, characterized in that, The method of calculating the grid recovery health index based on the estimated system short-circuit capacity, the voltage recovery slope and the frequency deviation comprises: GRHI = w1 * norm(V slope )+ w2 * (1 - norm(f dev ))+ w3 * norm(SC cap-est ); where norm(·) is a normalization function, w1, w2, and w3 are preset weighting weights, V slope is a voltage recovery slope, f dev is a frequency deviation and SC cap-est is an estimated system short circuit capacity.

6. The wind power converter low voltage ride through coordinated control method according to claim 1, characterized in that, calculating the grid recovery health index based on the estimated system short-circuit capacity, the voltage recovery slope and the frequency deviation with a formula as follows: The method of making a wind turbine localized recovery slope decision based on the grid recovery health index, a DC bus voltage and a maximum allowed recovery slope to obtain an adaptive active power recovery slope comprises: multiplying the grid recovery health index by the maximum allowed recovery slope to obtain a basic active power recovery slope; calculating a local correction factor based on the DC bus voltage; multiplying the local correction factor by the base active power recovery slope to obtain the adaptive active power recovery slope.

7. The wind power converter low voltage ride through coordinated control method according to claim 1, characterized in that, generating a smooth active power recovery execution based on the adaptive active power recovery slope, the pre-fault active power, and the suppressed active power command to obtain an active power during recovery reference value, including: setting an initial value of the active power during recovery reference value as the suppressed active power command; calculating an elapsed time based on a current time and a recovery start timestamp; performing an unlimited ramp update of the active power during recovery reference value based on the elapsed time to obtain an unlimited updated value of the active power during recovery reference value; taking a smaller value of the unlimited updated value of the active power during recovery reference value and the pre-fault active power as an updated value of the active power during recovery reference value.

8. The wind power converter low voltage ride through coordinated control method according to claim 1, characterized in that, generating a coordinated recovery instruction execution based on the active power during recovery reference value, the reactive current support reference value, d-q axis grid current feedback, and d-q axis grid voltage feedback to obtain a PWM pulse signal, including: calculating d-q axis current reference values based on the active power during recovery reference value, the reactive current support reference value, and d-q axis grid voltage feedback by an outer loop controller of the converter; comparing the d-q axis grid current feedback and the d-q axis current reference values by a current inner loop through a PI controller to obtain d-q axis voltage compensation values; performing coordinate inverse transformation and space vector modulation on the d-q axis voltage compensation values to obtain the PWM pulse signal.

9. A wind power converter low voltage ride through coordinated control system, characterized in that, including: an LVRT normal response analysis module for performing fault detection and LVRT normal response based on grid voltage effective value and grid guide LVRT curve to obtain a reactive current support reference value and a suppressed active power command; a grid recovery state evaluation module for performing grid recovery state evaluation based on PCC point voltage waveform, PCC point real-time frequency, and estimated system short-circuit capacity to obtain a grid recovery health index; a wind turbine local recovery decision module for performing wind turbine local recovery slope decision based on the grid recovery health index, DC bus voltage, and maximum allowable recovery slope to obtain an adaptive active power recovery slope; an active power recovery module for generating a smooth active power recovery execution based on the adaptive active power recovery slope, the pre-fault active power, and the suppressed active power command to obtain an active power during recovery reference value; a recovery instruction generation module for generating a coordinated recovery instruction execution based on the active power during recovery reference value, the reactive current support reference value, d-q axis grid current feedback, and d-q axis grid voltage feedback to obtain a PWM pulse signal.

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