Network construction type converter low voltage ride through control method and system based on voltage drop depth dynamic adjustment, and storage medium

Abstract

The invention discloses a network construction type converter low voltage ride through control method and system based on voltage sag depth dynamic adjustment, and a storage medium. The method comprises the following steps: dividing voltage sag depth grades; collecting a grid-connected point voltage signal for preprocessing, calculating the voltage drop depth according to the preprocessed voltage, and judging the level of the voltage drop depth; if the voltage sag depth is in a normal state, traditional VSG control is executed to complete low voltage ride through, otherwise, the reactive-voltage sag coefficient, the output reactive power and the virtual impedance are updated according to the voltage sag depth; when the voltage drop is not recovered to a normal state or is recovered to be normal but does not last for a set time, continuously carrying out the process after dividing the depth grade of the voltage drop, otherwise, adjusting the droop coefficient according to discretization exponential attenuation, and recovering the active power according to a discretization active slope recovery strategy; according to the invention, the power grid support efficiency and safety in the low voltage ride through process can be improved, and secondary oscillation in the recovery period can be avoided.

Description

Technical Field

[0001] This invention relates to the field of grid-connected voltage safety control for new energy sources, and in particular to a low-voltage ride-through control method, system, and storage medium for grid-connected converters based on dynamic adjustment of voltage drop depth. Background Technology

[0002] With the large-scale grid connection of new energy power generation, the low-voltage ride-through (LVRT) capability of grid-connected converters has become crucial for ensuring grid stability. Current mainstream control strategies suffer from the following problems:

[0003] First, the dynamic response of reactive power support is lagging, which manifests as: rigid droop coefficient: a fixed droop coefficient cannot adapt to the real-time operating conditions of the converter (such as changes in active power output), resulting in the reactive power output capacity not being fully utilized; coarse hierarchical control: the traditional binary method (normal / fault) is difficult to match the demand for different degrees of voltage drop, and is prone to over-compensation or under-compensation when there is a slight drop.

[0004] Secondly, the overcurrent suppression capability is insufficient: traditional virtual impedance technology mostly adopts fixed parameter design, which cannot effectively limit the fault current when there is a deep voltage drop, causing the converter output current to exceed the safety threshold, resulting in equipment disconnection or even hardware damage.

[0005] Finally, the step power recovery strategy adopted during the LVRT shutdown phase triggers a secondary oscillation, which causes a sudden change in active power, resulting in frequency fluctuations, and a sudden decrease in reactive power, causing voltage overshoot. This not only prolongs the fault recovery time but also intensifies the electrical stress on the equipment. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a low-voltage ride-through control method, system, and storage medium for grid-type converters based on dynamic adjustment of voltage drop depth, which can improve the grid support efficiency and safety during low-voltage ride-through and avoid secondary oscillations during the recovery period.

[0007] Technical solution: The low-voltage ride-through control method for grid-type converters based on dynamic adjustment of voltage sag depth described in this invention includes the following processes:

[0008] The voltage drop depth is divided into a set number of levels, and a certain level is determined as the normal state.

[0009] Data acquisition: Collect the voltage signal at the grid connection point, preprocess it, calculate the voltage drop depth based on the preprocessed voltage, and determine its level;

[0010] Low Voltage Ride-Through: If the voltage sag depth is within the normal range, conventional VSG control is executed; otherwise, the reactive power-voltage droop factor is updated based on the voltage sag depth, the apparent power of the grid-connected converter, and the active power. The reactive power output of the grid-connected converter is calculated based on the voltage sag depth and its corresponding level; the higher the voltage sag depth level, the greater the reactive power output of the grid-connected converter. The virtual impedance between the grid-connected converter and the grid connection point is updated based on the voltage sag depth. If the voltage sag does not recover to the normal range or the recovery to the normal range does not last for the set time, data acquisition and low voltage ride-through are continuously performed.

[0011] Once the voltage drops back to normal and remains so for a set period of time, the reactive power-voltage droop coefficient is adjusted according to the discretized exponential decay, and the active power is restored according to the discretized active power ramp recovery strategy.

[0012] Based on the above technical solution, by acquiring voltage signals and preprocessing them to calculate the voltage sag depth, and adaptively updating the reactive power-voltage droop coefficient according to the voltage sag depth, reactive power output can be adjusted more quickly, providing stronger voltage support and effectively preventing further voltage collapse. This fully utilizes reactive power and improves the reactive power response rate. By classifying voltage sag into five levels and calculating the corresponding reactive power output of the grid-connected converter based on the sag level, the reactive power output of the grid-connected converter can be controlled. Compared to the traditional binary method, which cannot flexibly and accurately adjust based on the sag depth during voltage sags, this approach offers a more comprehensive solution. By matching the reactive power support, this method can achieve more accurate and faster power support. Furthermore, by dynamically updating the virtual impedance through voltage sag depth, the virtual impedance increases with the sag depth, effectively suppressing overcurrent and preventing grid disconnection during deep sags. Upon exiting the low-voltage ride-through phase (recovery phase), the active power recovery strategy, achieved through discretized exponential decay adjustment of the reactive-voltage droop coefficient and discretized active power ramp recovery, eliminates step power surges and achieves smooth recovery. In summary, this method improves reactive power response speed and support capability, avoids overcurrent phenomena, and achieves smooth recovery.

[0013] Preferably, the formula for calculating the reactive power output of the grid-type converter is as follows:

[0014]

[0015] in, S represents the reactive power output of a grid-connected converter. n k1 represents the apparent power of the new energy system; k1, k2, and k3 are the reactive power coefficients, with values ​​ranging from [0,1] and k1... <k2<k3。

[0016] The above formula binds the output reactive power to the voltage drop depth. The deeper the drop, the greater the output reactive power. Compared to a fixed output reactive power, this provides faster and more accurate power support and improves the voltage recovery speed.

[0017] The low-voltage ride-through control method system for grid-type converters based on dynamic adjustment of voltage sag depth as described in this invention includes:

[0018] Level Classification Module: Used to classify voltage drop depth into a set number of levels and determine a certain level as the normal state;

[0019] Data acquisition module: used to acquire grid connection point voltage signals for preprocessing, calculate voltage drop depth based on the preprocessed voltage, and determine its level;

[0020] Low Voltage Ride-Through Module: This module determines whether to execute traditional VSG control if the voltage sag depth is within the normal range; otherwise, it updates the reactive power-voltage droop coefficient based on the voltage sag depth, the apparent power of the grid-connected converter, and the active power. It also calculates the reactive power output of the grid-connected converter based on the voltage sag depth and its corresponding voltage sag level; higher voltage sag levels result in greater reactive power output from the grid-connected converter. Furthermore, it updates the virtual impedance between the grid-connected converter and the grid connection point based on the voltage sag depth. If the voltage sag does not recover to normal or fails to maintain normal operation for the set time, it continuously collects data and performs low voltage ride-through.

[0021] Recovery module: Used to restore active power by adjusting the reactive power-voltage droop coefficient according to the discretized exponential decay after the voltage drops back to normal and continues for a set time, and by using the discretized active power ramp recovery strategy.

[0022] The computer-readable storage medium for storing one or more programs according to the present invention includes one or more programs comprising instructions that, when executed by a computing device, cause the computing device to perform any of the methods described above.

[0023] Beneficial effects: Dynamically updating the reactive power-voltage droop coefficient and virtual impedance by voltage sag depth improves the reactive power response rate and suppresses overcurrent, respectively. By dividing the voltage sag depth into five levels and calculating the output reactive power at each level, faster and more accurate power support can be achieved, improving the voltage recovery speed. During the recovery phase, smooth recovery is achieved through exponential decay and ramp recovery strategies. Attached Figure Description

[0024] Figure 1 The traditional VSG control block diagram;

[0025] Figure 2 This is a block diagram of the adaptive reactive power droop coefficient regulator of the present invention;

[0026] Figure 3 This is the improved grid-connected equivalent model of the present invention after introducing virtual impedance;

[0027] Figure 4 This is a flowchart of the method of the present invention. Detailed Implementation

[0028] As shown in the figure, the low-voltage ride-through control method for grid-type converters based on dynamic adjustment of voltage sag depth according to the present invention includes the following process:

[0029] Voltage drop depth is divided into five levels, with the drop depth increasing sequentially from low to high, and the lowest level being the normal state; the five levels from low to high are: normal state, mild drop, moderate drop, deep drop and severe drop.

[0030] Data acquisition: The voltage signal at the grid connection point is acquired, transformed into the dq coordinate system, and then the amplitude is processed by the sliding window RMS algorithm. After that, it is filtered by a Butterworth first-order filter to obtain the preprocessed voltage.

[0031] The formula for processing amplitude using the sliding window RMS algorithm is as follows:

[0032]

[0033] Among them, V g,rms Here, N represents the effective value of the grid connection point voltage, and N is the number of samples within the sliding window. and These are the components of the grid connection point voltage of the nth sample on the d-axis and q-axis, respectively. In this embodiment, the sliding window width is 10ms and the data update step size is 1ms, which can be adjusted as needed.

[0034] The amplitude is optimized using a sliding window RMS algorithm, and then filtered using a Butterworth first-order filter to obtain the preprocessed voltage V′. g,rms .

[0035] The voltage sag depth is calculated based on the pre-processed voltage to determine its level. The formula for calculating the voltage sag depth is as follows:

[0036]

[0037] Where ΔV is the voltage drop depth at the grid connection point, V ref V′ is the reference value for the phase voltage at the grid connection point. g,rms The preprocessed voltage is the voltage after the amplitude is optimized by the sliding window RMS algorithm and then filtered by the Butterworth first-order filter.

[0038] The voltage drop depth level is determined according to the following rules:

[0039] ① Normal state: when 0 < ΔV ≤ 0.1;

[0040] ② Mild drop: 0.1 < ΔV ≤ 0.2;

[0041] ③ Moderate drop: 0.2 < ΔV ≤ 0.5;

[0042] ④ Depth drop: 0.5 < ΔV ≤ 0.8;

[0043] ⑤ Severe drop: 0.8 < ΔV ≤ 1.0.

[0044] Low voltage ride-through: If the voltage drop depth is within the normal range, perform conventional VSG control; otherwise, proceed as follows:

[0045] Adaptive reactive power droop factor adjustment: The reactive power-voltage droop factor is updated based on the voltage sag depth, the apparent power of the grid-type converter, and the active power.

[0046] Specifically, the formula for calculating the reactive power-voltage droop factor is as follows:

[0047]

[0048] Where, k Q.t The reactive power-voltage droop coefficient at time t; and These represent the maximum and minimum reactive power of the new energy system at time t, respectively.

[0049] and The calculation formula is:

[0050]

[0051] Among them, S n P represents the apparent power of a new energy system. t Let t be the active power of the new energy system at time t.

[0052] Update the output reactive power: Calculate the reactive power output of the grid-type converter based on the voltage sag depth and its level. The higher the voltage sag depth level, the greater the reactive power output of the grid-type converter.

[0053] Specifically, the formula for calculating the reactive power output of a grid-connected converter is as follows:

[0054]

[0055] in, S represents the reactive power output of a grid-connected converter. ndenoted as the apparent power of the new energy system; k1, k2, and k3 are reactive power coefficients, with values ​​ranging from [0,1] and k1 < k2 < k3.

[0056] Update the virtual impedance between the grid-type converter and the grid connection point based on the voltage sag depth;

[0057] The transient output current of the grid-connected converter is limited to within 1.2 pu. Assume that the grid-connected converter is connected to the grid at its rated power before the grid connection point voltage drops, and ignore R. f and L f The virtual impedance calculation formula is obtained.

[0058]

[0059] Among them, Z v For virtual impedance, i N (t) represents the rated current value at the grid connection point at time t.

[0060] After introducing virtual impedance, the expression for the instantaneous value of fault current after voltage drop at the grid connection point is:

[0061]

[0062] Where i(t) represents the fault current at time t due to the voltage drop at the grid connection point; i (0-) This indicates the current output by the converter before the grid connection point voltage drops. and These represent the grid connection point voltages before and after the voltage drop; R f and L f The decibels represent the resistance and inductance of the filter circuit; i s (t) represents the steady-state component of the fault current at time t, where the grid connection point voltage drops; i t (t) represents the transient component of the fault current due to the voltage drop at the grid connection point at time t.

[0063] If the voltage drops and does not return to normal or does not remain at normal for the set time, data acquisition and low voltage ride-through will continue.

[0064] When the voltage drops back to normal and remains so for a set time, specifically when 0 < ΔV ≤ 0.1 and lasts for 100ms, the grid voltage is determined to have returned to normal, and the LVRT mode is exited. The set time can be adjusted according to the actual situation. The reactive power-voltage droop coefficient is adjusted according to the discrete exponential decay, and the active power is restored according to the discrete active power ramp recovery strategy.

[0065] The formula for calculating the reactive power-voltage droop coefficient of discretized exponential decay regulation is as follows:

[0066] K q [n] = Kq [n-1]e -Δt / τ

[0067] Among them, K q [n] represents the reactive power-voltage droop coefficient for the nth control cycle; Δt represents the sampling period of the control system; and τ represents the time constant.

[0068] The formula for calculating the restored active power using the discretized active power ramp recovery strategy is as follows:

[0069] P ref [n] = P ref [n-1]+k * Δt

[0070] Among them, P ref [n] represents the active power reference value for the nth control cycle; k * The slope represents the active power recovery rate, and Δt represents the sampling period of the control system.

[0071] The low-voltage ride-through control method system for grid-type converters based on dynamic adjustment of voltage sag depth as described in this invention includes:

[0072] Level Classification Module: Used to classify voltage drop depth into a set number of levels and determine a certain level as the normal state;

[0073] Voltage drop depth is divided into five levels, with the drop depth increasing sequentially from low to high, and the lowest level being the normal state; the five levels from low to high are: normal state, mild drop, moderate drop, deep drop and severe drop.

[0074] The formula for calculating voltage drop depth is:

[0075]

[0076] Where ΔV is the voltage drop depth at the grid connection point, V ref V′ is the reference value for the phase voltage at the grid connection point. g,rms This is the voltage after preprocessing;

[0077] The voltage drop depth level is determined according to the following rules:

[0078] ① Normal state: when 0 < ΔV ≤ 0.1;

[0079] ② Mild drop: 0.1 < ΔV ≤ 0.2;

[0080] ③ Moderate drop: 0.2 < ΔV ≤ 0.5;

[0081] ④ Depth drop: 0.5 < ΔV ≤ 0.8;

[0082] ⑤ Severe drop: 0.8 < ΔV ≤ 1.0.

[0083] Data acquisition module: used to acquire grid connection point voltage signals for preprocessing, calculate voltage drop depth based on the preprocessed voltage, and determine its level;

[0084] Preprocessing includes transforming the acquired voltage signal to the dq coordinate system, processing the amplitude using the sliding window RMS algorithm, and then filtering it using a Butterworth first-order filter. The formula for processing the amplitude using the sliding window RMS algorithm is as follows:

[0085]

[0086] Among them, V g,rms Here, N represents the effective value of the grid connection point voltage, and N is the number of samples within the sliding window. and These are the components of the grid connection point voltage of the nth sample on the d-axis and q-axis, respectively. In this embodiment, the sliding window width is 10ms and the data update step size is 1ms, which can be adjusted as needed.

[0087] The amplitude is optimized using a sliding window RMS algorithm, and then filtered using a Butterworth first-order filter to obtain the preprocessed voltage V′. g,rms .

[0088] Low Voltage Ride-Through Module: This module determines whether to execute traditional VSG control if the voltage sag depth is within the normal range; otherwise, it updates the reactive power-voltage droop coefficient based on the voltage sag depth, the apparent power of the grid-connected converter, and the active power. It also calculates the reactive power output of the grid-connected converter based on the voltage sag depth and its corresponding voltage sag level; higher voltage sag levels result in greater reactive power output from the grid-connected converter. Furthermore, it updates the virtual impedance between the grid-connected converter and the grid connection point based on the voltage sag depth. If the voltage sag does not recover to normal or fails to maintain normal operation for the set time, it continuously collects data and performs low voltage ride-through.

[0089] Adaptive reactive power droop factor adjustment: The reactive power-voltage droop factor is updated based on the voltage sag depth, the apparent power of the grid-type converter, and the active power; the formula for calculating the reactive power-voltage droop factor is as follows:

[0090]

[0091] Where, k Q.t The reactive power-voltage droop coefficient at time t; and These represent the maximum and minimum reactive power of the new energy system at time t, respectively.

[0092] and The calculation formula is:

[0093]

[0094] Among them, S n P represents the apparent power of a new energy system. t Let t be the active power of the new energy system at time t.

[0095] Updated output reactive power: The reactive power output of the grid-connected converter is calculated based on the voltage sag depth and its corresponding level. The higher the voltage sag depth level, the greater the reactive power output of the grid-connected converter. The formula for calculating the reactive power output of the grid-connected converter is as follows:

[0096]

[0097] in, S represents the reactive power output of a grid-connected converter. n denoted as the apparent power of the new energy system; k1, k2, and k3 are reactive power coefficients, with values ​​ranging from [0,1] and k1 < k2 < k3.

[0098] Update the virtual impedance between the grid-type converter and the grid connection point based on the voltage sag depth;

[0099] The transient output current of the grid-connected converter is limited to within 1.2 pu. Assume that the grid-connected converter is connected to the grid at its rated power before the grid connection point voltage drops, and ignore R. f and L f The virtual impedance calculation formula is obtained.

[0100]

[0101] Among them, Z v For virtual impedance, i N (t) represents the rated current value at the grid connection point at time t.

[0102] Recovery module: Used to restore active power by adjusting the reactive power-voltage droop coefficient according to the discretized exponential decay after the voltage drops back to normal and continues for a set time, and by using the discretized active power ramp recovery strategy.

[0103] If the voltage drops and does not return to normal or does not remain at normal for the set time, data acquisition and low voltage ride-through will continue.

[0104] When the voltage drops back to normal and remains so for a set time, specifically when 0 < ΔV ≤ 0.1 and lasts for 100ms, the grid voltage is determined to have returned to normal, and the LVRT mode is exited. The set time can be adjusted according to the actual situation. The reactive power-voltage droop coefficient is adjusted according to the discrete exponential decay, and the active power is restored according to the discrete active power ramp recovery strategy.

[0105] The formula for calculating the reactive power-voltage droop coefficient of discretized exponential decay regulation is as follows:

[0106] K q [n] = K q [n-1]e -Δt / τ

[0107] Among them, K q [n] represents the reactive power-voltage droop coefficient for the nth control cycle; Δt represents the sampling period of the control system; τ represents the time constant.

[0108] The formula for calculating the restored active power using the discretized active power ramp recovery strategy is as follows:

[0109] P ref [n] = P ref [n-1]+k * Δt

[0110] Among them, P ref [n] represents the active power reference value for the nth control cycle; k * The slope represents the active power recovery rate, and Δt represents the sampling period of the control system.

[0111] The computer-readable storage medium for storing one or more programs according to the present invention includes one or more programs comprising instructions that, when executed by a computing device, cause the computing device to perform any of the methods described above.

Claims

1. A low-voltage ride-through control method for grid-type converters based on dynamic adjustment of voltage sag depth, characterized in that, include: The voltage drop depth is divided into a set number of levels, and a certain level is determined as the normal state; Collect and preprocess the voltage signal at the grid connection point, calculate the voltage drop depth based on the preprocessed voltage, and determine its level. If the voltage sag depth is within the normal range, traditional VSG control is executed; otherwise, the reactive power-voltage droop coefficient is updated based on the voltage sag depth, the apparent power of the grid-connected converter, and the active power. The reactive power output of the grid-connected converter is calculated based on the voltage sag depth and its corresponding level; the higher the voltage sag depth level, the greater the reactive power output of the grid-connected converter. The virtual impedance between the grid-connected converter and the grid connection point is updated based on the voltage sag depth. If the voltage sag does not recover to the normal range or the recovery to the normal range fails to last for the set time, data acquisition and low-voltage ride-through are continuously performed. Once the voltage drops back to normal and remains so for a set period of time, the reactive power-voltage droop coefficient is adjusted according to the discretized exponential decay, and the active power is restored according to the discretized active power ramp recovery strategy.

2. The method according to claim 1, characterized in that: The formula for calculating voltage drop depth is: Where ΔV is the voltage drop depth at the grid connection point, V ref V′ is the reference value for the phase voltage at the grid connection point. g,rms This is the voltage after preprocessing; The voltage drop depth level is determined according to the following rules: ① Normal state: when 0 < ΔV ≤ 0.1; ② Mild drop: 0.1 < ΔV ≤ 0.2; ③ Moderate drop: 0.2 < ΔV ≤ 0.5; ④ Depth drop: 0.5 < ΔV ≤ 0.8; ⑤ Severe drop: 0.8 < ΔV ≤ 1.

0.

3. The method according to claim 2, characterized in that: The formula for calculating the reactive power-voltage droop coefficient is as follows: Where, k Q.t The reactive power-voltage droop coefficient at time t; and These represent the maximum and minimum reactive power of the new energy system at time t, respectively. and The calculation formula is: Among them, S n P represents the apparent power of a new energy system. t Let t be the active power of the new energy system at time t.

4. The method according to claim 2, characterized in that: The formula for calculating the reactive power output of the grid-type converter is as follows: in, S represents the reactive power output of a grid-connected converter. n k1 represents the apparent power of the new energy system; k1, k2, and k3 are the reactive power coefficients, with values ​​ranging from [0,1] and k1 < k2. <k3。 5. The method according to claim 2, characterized in that: The formula for calculating the virtual impedance is as follows: Among them, Z v For virtual impedance, i N (t) represents the rated current value at the grid connection point at time t.

6. The method according to claim 1, characterized in that: The formula for calculating the discrete exponential decay regulation reactive power-voltage droop coefficient is as follows: K q [n]=K q [n-1]e -Δt / τ Among them, K q [n] represents the reactive power-voltage droop coefficient for the nth control cycle; Δt represents the sampling period of the control system; τ represents the time constant. The formula for calculating the restored active power using the discretized active power ramp recovery strategy is as follows: P ref [n]=P ref [n-1]+k * Δt Among them, P ref [n] represents the active power reference value for the nth control cycle; k * The slope represents the active power recovery rate, and Δt represents the sampling period of the control system.

7. The method according to claim 1, characterized in that: The preprocessing includes transforming the acquired voltage signal to the dq coordinate system, processing the amplitude using the sliding window RMS algorithm, and then filtering it using a Butterworth first-order filter.

8. The method according to claim 7, characterized in that: The formula for processing amplitude in the sliding window RMS algorithm is as follows: Among them, V g,rms Here, N represents the effective value of the grid connection point voltage, and N is the number of samples within the sliding window. and These are the components of the grid connection point voltage of the nth sample on the d-axis and q-axis, respectively.

9. A low-voltage ride-through control method system for grid-type converters based on dynamic adjustment of voltage sag depth, characterized in that, The system includes: Level Classification Module: Used to classify voltage drop depth into a set number of levels and determine a certain level as the normal state; Data acquisition module: used to acquire grid connection point voltage signals for preprocessing, calculate voltage drop depth based on the preprocessed voltage, and determine its level; Low Voltage Ride-Through Module: This module determines whether to execute traditional VSG control if the voltage sag depth is within the normal range; otherwise, it updates the reactive power-voltage droop coefficient based on the voltage sag depth, the apparent power of the grid-connected converter, and the active power. It also calculates the reactive power output of the grid-connected converter based on the voltage sag depth and its corresponding voltage sag level; higher voltage sag levels result in greater reactive power output from the grid-connected converter. Furthermore, it updates the virtual impedance between the grid-connected converter and the grid connection point based on the voltage sag depth. If the voltage sag does not recover to normal or fails to maintain normal operation for the set time, it continuously collects data and performs low voltage ride-through. Recovery module: Used to restore active power by adjusting the reactive power-voltage droop coefficient according to the discretized exponential decay after the voltage drops back to normal and continues for a set time, and by using the discretized active power ramp recovery strategy.

10. The system according to claim 9, characterized in that: The formula for calculating voltage sag depth in the classification module is as follows: Where ΔV is the voltage drop depth at the grid connection point, V ref V′ is the reference value for the phase voltage at the grid connection point. g,rms This is the voltage after preprocessing; The voltage drop depth level is determined according to the following rules: ① Normal state: when 0 < ΔV ≤ 0.1; ② Mild drop: 0.1 < ΔV ≤ 0.2; ③ Moderate drop: 0.2 < ΔV ≤ 0.5; ④ Depth drop: 0.5 < ΔV ≤ 0.8; ⑤ Severe drop: 0.8 < ΔV ≤ 1.

0.

11. The system according to claim 10, characterized in that: The formula for calculating the reactive power-voltage droop coefficient in the low-voltage ride-through module is as follows: Where, k Q.t The reactive power-voltage droop coefficient at time t; and These represent the maximum and minimum reactive power of the new energy system at time t, respectively. and The calculation formula is: Among them, S n P represents the apparent power of a new energy system. t Let t be the active power of the new energy system at time t.

12. The system according to claim 10, characterized in that: The formula for calculating the reactive power output of the grid converter in the low-voltage ride-through module is as follows: in, S represents the reactive power output of a grid-connected converter. n k1 represents the apparent power of the new energy system; k1, k2, and k3 are the reactive power coefficients, with values ​​ranging from [0,1] and k1... <k2<k3。 13. The system according to claim 10, characterized in that: The formula for calculating the virtual impedance in the low-voltage ride-through module is as follows: Among them, Z v For virtual impedance, i N (t) represents the rated current value at the grid connection point at time t.

14. The system according to claim 9, characterized in that: The formula for calculating the discrete exponential decay regulation reactive power-voltage droop coefficient in the recovery module is as follows: K q [n]=K q [n-1]e -Δt / τ Among them, K q [n] represents the reactive power-voltage droop coefficient for the nth control cycle; Δt represents the sampling period of the control system; τ represents the time constant. The formula for calculating the restored active power using the discretized active power ramp recovery strategy is as follows: P ref [n]=P ref [n-1]+k * Δt Among them, P ref [n] represents the active power reference value for the nth control cycle; k * The slope represents the active power recovery rate, and Δt represents the sampling period of the control system.

15. The system according to claim 9, characterized in that: The data acquisition module includes preprocessing the acquired voltage signal by transforming it to the dq coordinate system, processing the amplitude using a sliding window RMS algorithm, and then filtering it using a Butterworth first-order filter.

16. The system according to claim 15, characterized in that: The formula for processing amplitude in the sliding window RMS algorithm is as follows: Among them, V g,rms Here, N represents the effective value of the grid connection point voltage, and N is the number of samples within the sliding window. and These are the components of the grid connection point voltage of the nth sample on the d-axis and q-axis, respectively.

17. A computer-readable storage medium for storing one or more programs, characterized in that: The program includes one or more instructions that, when executed by a computing device, cause the computing device to perform any of the methods according to claims 1 to 8.

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