Active arc suppression method for generator stator grounding fault based on dual-loop quasi-PR control

Abstract

This invention discloses an active arc suppression method for generator stator grounding faults based on dual-loop quasi-PR control, comprising the following steps: S1. Monitoring the fundamental zero-sequence voltage and third harmonic voltage at the generator neutral point and terminals, and performing fault phase selection and location when a single-phase stator grounding fault occurs; S2. Calculating the fault winding potential based on the fault location results. E f And negative it – E f S3. Set the neutral point target compensation voltage; S4. Adopt a topology structure of cascaded H-bridge converters as active control devices, and establish a dual closed-loop control framework consisting of an outer voltage loop and an inner current loop; S5. Set quasi-PR control units for the fundamental and third harmonic components in the outer voltage loop and the inner current loop, respectively; S6. Control the output of the cascaded H-bridge converter to the target compensation voltage – E f A consistent compensation voltage is injected into the generator neutral point. This invention improves the voltage regulation accuracy and arc suppression speed during the active arc suppression process of the generator, thereby enhancing the safety and reliability of generator operation.

Description

Technical Field

[0001] This invention relates to the field of safety protection technology for large generators, specifically to an active arc suppression method for generator stator grounding faults based on dual-loop quasi-PR control. Background Technology

[0002] Single-phase grounding faults in generator stators are among the most common and dangerous fault types in power systems. The high temperature and overvoltage generated by the electric arc can damage insulation and threaten the safety of the generator unit. With the increase in generator capacity and voltage level, the energy of the grounding arc has increased significantly, and quickly and effectively suppressing the arc has become an important issue for the safe operation of generators.

[0003] Currently, generator neutral point grounding protection mostly adopts passive arc suppression methods, which compensate for capacitive current through arc suppression coils or high-resistance grounding resistors. This type of method is simple in structure and low in cost, but the compensation effect is significantly affected by changes in system parameters. It can only suppress the fundamental component and has limited effect on high-frequency and harmonic currents. Under changing operating conditions, it is prone to insufficient or over-compensation, making it difficult to completely extinguish the arc.

[0004] With the development of power electronics technology, active arc suppression methods can theoretically achieve full-frequency arc suppression by injecting controllable voltage or current into the neutral point to actively compensate for the voltage at the fault point. However, research on active arc suppression control for generators is still limited, and existing methods are mostly based on distribution network scenarios, whose control accuracy and response speed are difficult to meet the requirements of strong coupling and high harmonic characteristics of generators.

[0005] While commonly used PI control is simple in structure, it suffers from large steady-state errors and insufficient phase margins under conditions involving harmonics and dynamic arcing. Traditional PR control can achieve zero steady-state error tracking of the fundamental component, but its gain attenuation is significant in the third and higher harmonic frequency bands, making it difficult to ensure multi-frequency coordination. Model predictive control (MPC) has certain advantages in dynamic response, but it involves large computational loads, strong parameter dependence, and insufficient real-time performance. Furthermore, most of the above control strategies do not consider the coupling characteristics of the generator stator windings and the phase distortion of the third harmonic component, thus easily leading to response lag and control oscillations in practical applications, resulting in unstable arc suppression effects.

[0006] In summary, existing passive methods have limited compensation capabilities, and while active control offers advantages in proactive regulation, it lacks a systematic control strategy applicable to generators. There is an urgent need to propose a multi-frequency coordinated, fast-response, and robust active arc suppression control method to achieve precise suppression of fault voltage and reliable arc extinguishing. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an active arc suppression method for generator stator grounding faults based on dual-loop quasi-PR control, which can improve the voltage regulation accuracy and arc suppression speed in the active arc suppression process of the generator, thereby improving the safety and reliability of generator operation.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows.

[0009] An active arc suppression method for generator stator grounding faults based on dual-loop quasi-PR control includes the following steps:

[0010] S1. Monitor the fundamental zero-sequence voltage and third harmonic voltage at the generator neutral point and terminals, and determine whether a single-phase stator grounding fault has occurred in the generator based on the voltage signal; if yes, perform fault phase selection and location, and proceed to step S2; if no, continue monitoring.

[0011] S2. Based on the fault location results, calculate the fundamental component of the fault winding potential. E f1 and third harmonic components E f3 And will be determined by the fundamental component E f1 and third harmonic components E f3 Synthetic fault winding potential E f negative values ​​– E f Set as the neutral point target compensation voltage;

[0012] S3. A cascaded H-bridge converter is adopted as the topology of the active control device, and a dual closed-loop control framework consisting of an outer voltage loop and an inner current loop is established.

[0013] S4. Quasi-PR control units are set in the voltage outer loop and the current inner loop for the fundamental wave and the third harmonic component, respectively, so as to realize independent control of different frequency components;

[0014] S5. Controlling the output of the cascaded H-bridge converter and the target compensation voltage – E f A consistent compensation voltage is injected into the generator neutral point to suppress the fault point voltage and achieve arc suppression.

[0015] Preferably, in the dual closed-loop control framework of step S3:

[0016] The outer voltage loop is designed to compensate for the target voltage. E f To achieve the control target, the generator neutral point voltage is tracked and controlled, and a target current reference signal is output. I ref ;

[0017] The inner current loop uses the target current reference signal. I ref To achieve the control objective, the actual output current of the cascaded H-bridge converter should be aligned with the target current reference signal. I ref Correspondingly, this is used to regulate the output voltage of the cascaded H-bridge converter.

[0018] Preferably, the quasi-PR control unit in step S4 corresponds to the fundamental wave control channel and the third harmonic control channel, respectively, and their control transfer functions are as follows:

[0019]

[0020]

[0021] in, This represents the transfer function corresponding to the fundamental control channel of the quasi-PR control unit. This represents the transfer function corresponding to the third harmonic control channel of the quasi-PR control unit. K r1 Indicates the fundamental frequency PR gain. K r3 Indicates the third harmonic PR gain; Indicates the fundamental bandwidth. Indicates the bandwidth of the third harmonic; Indicates the fundamental angular frequency. Indicates the third harmonic angular frequency; Represents the complex frequency variable in the Laplace transform;

[0022] The fundamental frequency control channel is used to track and adjust the fundamental frequency voltage component at the neutral point, and the third harmonic control channel is used to accurately compensate the third harmonic voltage component at the neutral point. The two channels work in parallel to form a multi-frequency composite voltage control structure.

[0023] Preferably, the third harmonic control channel includes a phase lead compensation stage to correct the phase lag of the harmonic signal in the high-frequency response and improve control accuracy; the transfer function of the phase lead compensation stage is:

[0024]

[0025] In the formula, The transfer function for the phase lead compensation stage; α The lead factor of the phase compensator can be expressed as: , The phase compensation angle is T; T is the time constant, which can be expressed as .

[0026] Preferably, the fundamental angular frequency Third harmonic angular frequency .

[0027] Preferably, the output terminal of the cascaded H-bridge converter is equipped with an LCL filter for filtering out high-frequency components of the switching circuit. The LCL filter model is as follows:

[0028]

[0029] in, This is an LCL filter model; L 1 is the inductor on the cascaded H-bridge converter side. C For filtering capacitors, R Equivalent resistance R d This is the resistance of the damping branch.

[0030] Preferably, both the voltage outer loop and the current inner loop are provided with a first-order discrete low-pass filter to filter the error signal, and its discrete expression is:

[0031]

[0032] in, The discrete transfer function of the low-pass filter. These are the error filtering coefficients; z For a discrete system, it is a complex frequency variable;

[0033] An active damping element is provided in the inner current loop to compensate for the current error signal. Its expression is as follows:

[0034]

[0035] in, Let be the transfer function of the active damping element. For damping gain;

[0036] The filtering and active damping circuits reduce the impact of measurement noise and suppress the resonance effect caused by the LCL filter at the output of the cascaded H-bridge converter by filtering and damping the error signal.

[0037] Preferably, in step S5, the cascaded H-bridge converter outputs a voltage equal to the target compensation voltage through a multi-level synthesis method. E f Consistent compensation voltage.

[0038] Due to the adoption of the above technical solutions, the technical progress achieved by this invention is as follows.

[0039] This invention employs a dual closed-loop control framework with a voltage outer loop and a current inner loop working together in the control structure. Quasi-PR control units are established for the fundamental and third harmonic voltage components respectively, and a phase compensation stage is introduced in the third harmonic channel to make the output voltage and the fault voltage equal in amplitude and opposite in phase, thereby improving the synchronous control accuracy of multi-frequency composite voltage.

[0040] This invention employs a quasi-PR control unit to provide high gain at both the fundamental frequency and the third harmonic frequency, thereby achieving zero steady-state error tracking of multi-frequency composite compensation voltage. This fundamentally overcomes the shortcomings of traditional PI control in tracking AC signals due to steady-state errors.

[0041] This invention effectively suppresses the resonance problem caused by the LCL filter through the coordinated design of the voltage outer loop and the current inner loop, combined with active damping and error filtering. Under the premise of ensuring stability, it achieves a rapid dynamic response to faults.

[0042] This invention uses the negative value of the neutral point voltage at the fault point as the control target, which can quickly and accurately adjust the neutral point voltage to the set value, thereby achieving rapid suppression of fault current and effective extinguishing of electric arc, significantly improving the safety and reliability of generator operation.

[0043] This invention is insensitive to changes in generator impedance parameters, fault location, and grounding transition resistance. It does not rely on impedance parameters such as generator-to-ground capacitance and inductance, which are difficult to measure precisely. It has strong robustness to changes in fault location and transition resistance and broad adaptability to various operating conditions. It can maintain stable arc suppression performance and excellent dynamic response characteristics under different generator types and operating conditions, which is significantly better than feedforward open-loop control methods that rely on precise parameter calculations. Attached Figure Description

[0044] Figure 1 This is a flowchart of the present invention;

[0045] Figure 2 This is a simulation model diagram of the present invention;

[0046] Figure 3 The present invention sets the grounding resistance value to 200Ω. The simulation results compare the voltage tracking performance of PI and dual-loop quasi-PR at a voltage level of 0.25. Figure 3 (a) is a simulation result comparing the voltage tracking performance of the dual-loop quasi-PR. Figure 3 (b) is a simulation result graph comparing the voltage tracking performance of the PI controller;

[0047] Figure 4 The present invention sets the grounding resistance value to 200Ω. The simulation results compare the voltage tracking performance of PI and dual-loop quasi-PR at a voltage level of 0.5. Figure 4 (a) is a simulation result comparing the voltage tracking performance of the dual-loop quasi-PR. Figure 4 (b) is a simulation result graph comparing the voltage tracking performance of the PI controller;

[0048] Figure 5 The present invention sets the grounding resistance value to 200Ω. The simulation results compare the voltage tracking performance of PI and dual-loop quasi-PR at a voltage level of 0.75. Figure 5 (a) is a simulation result comparing the voltage tracking performance of the dual-loop quasi-PR. Figure 5 (b) is a simulation result diagram comparing the voltage tracking performance of the PI. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0050] An active arc suppression method for generator stator grounding faults based on dual-loop quasi-PR control, combined with Figure 1 As shown, it includes the following steps:

[0051] S1. Monitor the fundamental zero-sequence voltage and third harmonic voltage at the generator neutral point and terminals, and determine whether a single-phase stator grounding fault has occurred based on the voltage signal; if so, perform fault phase selection and location, and execute step S2; if not, continue monitoring.

[0052] In this step, the fundamental zero-sequence voltage and the third harmonic voltage at the generator neutral point and the generator terminals are monitored to sample the fundamental zero-sequence voltage and the third harmonic voltage at the generator neutral point and the generator terminals.

[0053] S2. Based on the fault location results, calculate the fundamental component of the fault winding potential. E f1 and third harmonic components E f3 And will be determined by the fundamental component E f1 and third harmonic components E f3 Synthetic fault winding potential E f negative values ​​– E f Set as the neutral point target compensation voltage.

[0054] This step calculates the target value of the control voltage, i.e., the target compensation voltage. E f .

[0055] Specifically, for generators with different structures, the winding distribution and magnetic coupling characteristics vary, therefore the specific calculation methods for the fault winding potential are not entirely the same. For example, steam turbine generators typically use an equivalent single-layer winding model to calculate the fault potential; hydro turbine generators, due to their larger number of pole pairs, need to consider the influence of inter-phase mutual inductance; and variable-speed pumped storage units, operating under variable frequency drive conditions, should have their equivalent capacitance parameters and angular velocity terms corrected. These calculation differences only affect the method of obtaining the fault winding potential value and have no impact on the implementation of the active arc suppression method of this invention.

[0056] In this invention, such as Figure 2 As shown, taking a single-phase ground fault in phase A as an example, the fundamental component of the fault winding potential satisfies:

[0057]

[0058]

[0059] in, This represents the amplitude of the fundamental component of the fault winding potential; Amplitude of the fundamental component of the phase potential of phase A of the generator stator winding; for and The angle between them This represents the fundamental component of the faulty winding potential. This represents the fundamental component of the phase potential of phase A of the generator stator winding. The fault turns ratio is the ratio of the number of coil turns from the fault point to the generator neutral point to the total number of series coil turns for that phase.

[0060] The third harmonic component of the fault winding potential satisfies:

[0061]

[0062]

[0063] in, The amplitude of the third harmonic component of the fault winding potential; Amplitude of the third harmonic component of the phase potential of phase A of the generator stator winding; for and The angle between them The third harmonic component of the fault winding potential. This represents the third harmonic component of the phase potential of phase A of the generator stator winding.

[0064] S3. A cascaded H-bridge converter is adopted as the topology of the active control device, and a dual closed-loop control framework consisting of an outer voltage loop and an inner current loop is established.

[0065] Specifically, in the dual-closed-loop control framework:

[0066] The outer voltage loop is designed to compensate for the target voltage. E f To achieve the control target, the generator neutral point voltage is tracked and controlled, and a target current reference signal is output. I ref ;

[0067] The inner current loop uses the target current reference signal. I ref To achieve the control objective, the actual output current of the cascaded H-bridge converter should be aligned with the target current reference signal. I ref Correspondingly, the output voltage of the cascaded H-bridge converter is adjusted to generate a voltage reference value through dual closed-loop control. This reference voltage is compared with the target compensation voltage. E f Consistent.

[0068] S4. Quasi-PR control units are set in the voltage outer loop and the current inner loop for the fundamental and third harmonic components, respectively, so as to achieve independent control of different frequency components.

[0069] Specifically, the quasi-PR control unit (i.e., the quasi-proportional resonant control unit) corresponds to the fundamental wave control channel and the third harmonic control channel, respectively, and their control transfer functions are as follows:

[0070]

[0071]

[0072] in, This represents the transfer function corresponding to the fundamental control channel of the quasi-PR control unit. This represents the transfer function corresponding to the third harmonic control channel of the quasi-PR control unit. K r1 Indicates the fundamental frequency PR gain. K r3 Indicates the third harmonic PR gain; Indicates the fundamental bandwidth. Indicates the bandwidth of the third harmonic; Indicates the fundamental angular frequency. Indicates the third harmonic angular frequency; This represents the complex frequency variable in the Laplace transform.

[0073] Furthermore, the quasi-PR control unit is divided into an outer-loop quasi-PR controller and an inner-loop quasi-PR controller, which are collectively referred to as the controller. Preferably, the fundamental angular frequency... Third harmonic angular frequency .

[0074] The fundamental frequency control channel is used to track and adjust the fundamental frequency voltage component at the neutral point, while the third harmonic control channel is used to accurately compensate for the third harmonic voltage component at the neutral point. The two channels work in parallel to form a multi-frequency composite voltage control structure.

[0075] Specifically, the third harmonic control channel suffers from inherent delays in sampling and holding as well as in the calculation output, resulting in phase lag in the third harmonic component. To compensate for this lag and ensure accurate tracking of the third harmonic, a phase lead compensation stage is incorporated into the third harmonic control channel to correct the phase lag of the harmonic signal in the high-frequency response and improve control accuracy. The transfer function of the phase lead compensation stage is:

[0076]

[0077] In the formula, The transfer function for the phase lead compensation stage; α The lead factor of the phase compensator can be expressed as: , The phase compensation angle is T; T is the time constant, which can be expressed as .

[0078] Specifically, the output of the cascaded H-bridge converter is equipped with an LCL filter model to filter out high-frequency components of the switching circuit. The LCL filter model is as follows:

[0079]

[0080] in, This is an LCL filter model; L 1 is the inductor on the cascaded H-bridge converter side. C For filtering capacitors, R Equivalent resistance R d This is the resistance of the damping branch.

[0081] Both the outer voltage loop and the inner current loop incorporate first-order discrete low-pass filters to filter the error signal. Their discrete expressions are as follows:

[0082]

[0083] in, The discrete transfer function of the low-pass filter. These are the error filtering coefficients; z Let be the complex frequency variable in the discrete system.

[0084] An active damping element is incorporated into the inner current loop to compensate for current error signals. Its expression is as follows:

[0085]

[0086] in, Let be the transfer function of the active damping element. This represents the damping gain.

[0087] The filtering and active damping circuits reduce the impact of measurement noise and suppress the resonance effect caused by the LCL filter at the output of the cascaded H-bridge converter by filtering and damping the error signal.

[0088] The complete transfer function for this step is:

[0089]

[0090] In the formula, Represents the complete transfer function of the voltage arc suppression method; G con ( s ) represents the transfer function of the controller, and G con ( s )= G in ( s ) G out ( s ) G damp ( s ) H LPF (s) 2 , G in ( s ) represents the transfer function of the inner loop current controller. G out ( s ) represents the transfer function of the outer loop voltage controller. H LPF (s) represents the transfer function of the low-pass filter; Indicates the target compensation voltage – E f The frequency domain form.

[0091] S5. Controlling the output of the cascaded H-bridge converter and the target compensation voltage – E f A consistent compensation voltage is injected into the generator neutral point to suppress the fault point voltage and achieve arc suppression.

[0092] Specifically, the target compensation voltage – E f By cascading H-bridge converters, the cascaded H-bridge converters achieve high-precision output voltage matching the target compensation voltage through multi-level synthesis. Ef Consistent compensation voltage, i.e., the same as the fault winding potential E f Compensation voltages with equal amplitude but opposite phase.

[0093] Example 1

[0094] Building in the MATLAB / Simulink software platform Figure 2 The figure shows an active arc suppression simulation model for generator stator grounding faults. E 1 represents the fundamental voltage of the coil. E 3 represents the third harmonic voltage of the coil. R coil This is the equivalent resistance of the coil. L coil This is the equivalent inductance of the coil. L The connection inductance is for the cascaded H-bridge converter. Specific simulation parameters are shown in Table 1. The simulation considers different ground fault locations and different ground resistance values.

[0095] Table 1 Simulation Parameters

[0096]

[0097] (1) The fault is set to occur in phase A, with a fault time of 0.025s. After the fault is detected, the active arc suppression device is activated at 0.1s, and the total simulation time is 0.4s. The active arc suppression method proposed in this invention is compared with PI control, and the results are as follows: Figures 3 to 5 As shown. Figures 3 to 5 The following table shows the output voltage comparison of the two control methods within the time range of 0.305s to 0.325s, with a grounding transition resistance of 200Ω and fault turns ratios of 0.25, 0.5, and 0.75, respectively. Figures 3 to 5 Analysis shows that the dual-closed-loop quasi-PR control in this invention can achieve more accurate zero-steady-state-error tracking of multiple harmonics compared to traditional PI control.

[0098] (2) In =0.125 to =1 A total of 8 fault points were set up with two fault modes: arc grounding and resistance grounding. The Cassie arc model was used for arc grounding, while the transition resistances for resistance grounding were 100Ω, 200Ω, 500Ω, and 1000Ω, respectively. The active arc suppression method proposed in this invention was implemented, and the effective value of the fault residue and the waveform of the fault current were recorded. The results are shown in Table 2:

[0099] Table 2

[0100]

[0101] Analysis of Table 2 shows that the dual-closed-loop quasi-PR control has excellent compensation effect on grounding faults under different grounding methods and different fault locations.

[0102] This invention proposes a systematic control method for active arc suppression technology in generators for the first time. This method does not require the measurement of generator impedance parameters. Through real-time feedback adjustment of neutral point voltage and current signals, it is applicable to different generator types and operating conditions. It can maintain stable arc suppression performance under different fault locations and transition resistance conditions, effectively eliminating arcs in a short time and significantly improving the safety and stability of generator operation. When the fault location or grounding transition resistance changes, it can automatically adjust the control output through a dual closed-loop control framework to maintain stable tracking of the neutral point voltage. It can be applied to both resistance grounding and arc grounding conditions and maintains dynamic stability of the arc suppression process under various operating environments.

Claims

1. A method for active arc extinction of a generator stator ground fault based on dual-loop quasi-PR control, characterized in that: The method comprises the following steps: S1. Monitoring the fundamental zero sequence voltage and the third harmonic voltage of the generator neutral point and the machine end, judging whether the single-phase stator ground fault of the generator occurs based on the voltage signal; if yes, proceed with fault phase selection and positioning, and perform step S2; if not, continue monitoring; S2. Based on the fault location results, calculate the fundamental component of the fault winding potential. E f1 and third harmonic components E f3 And will be determined by the fundamental component E f1 and third harmonic components E f3 Synthetic fault winding potential E f negative values ​​– E f Set as the neutral point target compensation voltage; S3. Using a cascaded H-bridge converter as the topology structure of the active regulation device, establishing a double-loop control framework composed of a voltage outer loop and a current inner loop; S4. Setting a quasi-PR control unit for the fundamental and third harmonic components in the voltage outer loop and the current inner loop, respectively, to realize independent regulation of different frequency components; S5. Control the cascaded H-bridge inverter output to target compensation voltage E f A consistent compensation voltage is generated and injected into the generator neutral to suppress the fault point voltage and achieve arc extinction.

2. The dual-loop quasi-PR control based method for active arc extinction in case of generator stator ground fault, as claimed in claim 1, wherein the said method comprises of the following steps: In the double-loop control framework of step S3: The voltage outer loop is to target compensation voltage E f For control target, the generator neutral point voltage is tracked and controlled, and the target current reference signal is output I ref ; The inner current loop is to target current reference signal I ref For control target, make the actual output current of the cascaded H-bridge converter consistent with the target current reference signal I ref Correspondingly, the output voltage of the cascaded H-bridge converter is adjusted.

3. The dual-loop quasi-PR control based method for active arc extinction in case of generator stator ground fault according to claim 1, characterized in that: The quasi-PR control unit in step S4 corresponds to a fundamental control channel and a third harmonic control channel, respectively, and their control transfer functions are: wherein G0(s) represents a transfer function corresponding to the fundamental control channel of the quasi-PR control unit, G3(s) represents a transfer function corresponding to the third harmonic control channel of the quasi-PR control unit, K r1 G0PR represents a fundamental PR gain, K r3 G3PR represents a third harmonic PR gain; G0BW represents a fundamental bandwidth, G3BW represents a third harmonic bandwidth; ω0 represents a fundamental angular frequency, ω3 represents a third harmonic angular frequency; s represents a complex frequency variable in the Laplace transform; The fundamental control channel is used to track and adjust the neutral point fundamental voltage component, and the third harmonic control channel is used to accurately compensate the neutral point third harmonic voltage component, both of which constitute a multi-frequency composite voltage control structure in parallel.

4. The dual-loop quasi-PR control based method for active arc extinction of a generator stator ground fault according to claim 3, characterized in that: A phase lead compensation link is set in the third harmonic control channel to correct the phase lag of the harmonic signal in high-frequency response and improve the control accuracy; the transfer function of the phase lead compensation link is: wherein is the phase lead compensator transfer function; α is the phase lead compensator transfer function; and , is the phase compensation angle; and T is the time constant, which can be expressed as .

5. The dual-loop quasi-PR control based generator stator ground fault active arc extinction method of claim 3, wherein: the fundamental angular frequency the third harmonic angular frequency .

6. The dual-loop quasi-PR control based generator stator ground fault active arc extinction method of claim 3, wherein: The output end of the cascaded H-bridge converter is provided with an LCL filter for filtering the high-frequency components of the switch, and the LCL filter model is: wherein, is the LCL filter model; L 1 is the side inductance of the cascaded H-bridge converter, C is the filter capacitance, R is the equivalent resistance, R d is the damping branch resistance.

7. The dual-loop quasi-PR control based method for active arc extinction of a generator stator ground fault according to claim 6, characterized in that: Both the voltage outer loop and the current inner loop are provided with a first-order discrete low-pass filter link for filtering the error signal, and its discrete expression is: wherein is a low-pass filter discrete transfer function, is an error filter coefficient; z is a complex frequency variable in a discrete system; An active damping link is set in the current inner loop for damping compensation of the current error signal, and its expression is: wherein is the active damping element transfer function, is the damping gain; The filter link and the active damping link reduce the influence of measurement noise and suppress the resonance effect caused by the LCL filter at the output end of the cascaded H-bridge converter by filtering and damping compensation of the error signal.

8. The dual ring quasi-PR control based generator stator ground fault active arc extinction method of claim 1, wherein: The cascade H-bridge converter in the step S5 outputs the target compensation voltage - Ucomp by a multi-level synthesis method E f consistent compensation voltage.

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