A method, system, and medium for ground fault protection of a static var generator

Abstract

The present application relates to the technical field of power system protection, and particularly relates to a static var generator grounding fault protection method, a system and a medium, comprising determining a grounding fault load distribution imbalance area of the static var generator according to a zero sequence grounding current characteristic quantity; in the grounding fault load distribution imbalance area, the electrical coupling stability of the fault area is evaluated according to electrical coupling correlation data between different component parts inside the static var generator, the current electrical stability state and a key influence component list are obtained, the load distribution of the grounding fault load distribution imbalance area is adjusted, and a load distribution optimization scheme is obtained; the optimal protection action timing is determined; the protection action instruction set is generated based on the optimal protection action timing and the load distribution optimization scheme, and the static var generator is controlled to perform grounding fault protection. The present application realizes fast, accurate and orderly protection action of the static var generator in the grounding fault through dynamic adjustment of the load distribution.

Description

Technical Field

[0001] This invention relates to the field of power system protection technology, and in particular to a method, system and medium for ground fault protection of a static var generator. Background Technology

[0002] In the field of power system protection and control, the Static Var Generator (SVG) is a core device of flexible AC transmission systems. Its reliability and stability are directly related to the power quality and dynamic voltage support capability of the power grid. However, with the continuous expansion of the scale and increasing complexity of the power system, the Static Var Generator faces many severe challenges in fault protection.

[0003] Currently, fault protection schemes for static var generators (SVRs) have revealed significant limitations in practical applications. Most existing SVR fault protection methods focus on protecting the entire device while severely neglecting the coordination between its internal components. This one-sidedness leads to inaccurate and ineffective protection actions during fault occurrence. For example, when a critical component fails and needs isolation, the lack of in-depth analysis of the dynamic relationships between components causes significant changes in the load distribution of other parts due to fault isolation. These changes disrupt the original equilibrium state of the device, introducing new instabilities in the electrical connections between components. More importantly, this instability directly affects the effectiveness of the protection strategy. Because the dynamic changes of each component during a fault cannot be accurately grasped, the timing and method of protection actions are difficult to precisely match actual needs. Inappropriate timing of protection actions may lead to an expansion of the fault range, while incorrect execution methods may trigger a chain reaction, further threatening the stability of the entire power system.

[0004] In summary, existing ground fault protection technologies for static var generators have many shortcomings, resulting in inaccurate protection actions during faults and making it difficult to effectively ensure the stable operation of the power system. Therefore, how to solve these problems in the existing technologies for static var generator fault protection has become a key challenge that urgently needs to be addressed in this field. Summary of the Invention

[0005] To address the above technical problems, this invention provides a method, system, and medium for ground fault protection of a static var generator.

[0006] In a first aspect, the present invention provides a method for protecting a static var generator from ground faults, the method comprising the following steps:

[0007] Based on the real-time three-phase current and voltage data during the operation of the static var generator, the zero-sequence grounding current characteristic quantity is extracted.

[0008] Based on the zero-sequence grounding current characteristics, determine the grounding fault load distribution imbalance area of ​​the static var generator;

[0009] In the ground fault load distribution imbalance area, the electrical coupling stability of the fault area is evaluated based on the electrical coupling correlation data between different components inside the static var generator, and the current electrical stability status and a list of key influencing components are obtained.

[0010] Based on the current electrical stability status and the list of key influencing components, the load distribution in the ground fault load distribution imbalance area is dynamically adjusted to obtain an optimized load distribution scheme.

[0011] Based on real-time voltage and current change rate data and typical ground fault waveforms, determine the optimal protection action timing;

[0012] Based on the optimal protection action timing and the load allocation optimization scheme, a protection action instruction set is generated, and the protection action instruction set is used to control the static var generator to perform ground fault protection.

[0013] In a further implementation, the step of extracting the zero-sequence grounding current characteristic quantity based on the real-time three-phase current and voltage data during the operation of the static var generator includes:

[0014] Real-time three-phase current and voltage data of each component inside the static var generator are collected in real time, and the real-time three-phase current and voltage data collected at the same sampling time are added together to obtain the instantaneous value of zero-sequence current.

[0015] The effective value of the zero-sequence current is obtained by performing an arithmetic average filter on the instantaneous value of the zero-sequence current within a single continuous power frequency cycle.

[0016] The absolute value of the difference between the effective values ​​of the zero-sequence current between two adjacent power frequency cycles is calculated based on the real-time three-phase current and voltage data to obtain the ground current mutation rate.

[0017] The system voltage phase information is obtained by real-time tracking of the phase change of the flexible AC transmission system voltage through a phase-locked loop synchronization system voltage phase.

[0018] The phase difference angle between the fundamental component of the grounding current and the zero-sequence component of the flexible AC transmission system voltage is calculated based on the system voltage phase information to obtain the phase offset.

[0019] The effective value of the zero-sequence current, the ground current mutation rate, and the phase offset are combined to form the zero-sequence ground current characteristic quantity.

[0020] In a further implementation, the step of determining the ground fault load distribution imbalance region of the static var generator based on the zero-sequence ground current characteristic includes:

[0021] The effective value of the zero-sequence current is compared with a preset ground fault threshold. When the effective value of the zero-sequence current exceeds the preset ground fault threshold, the physical location of the ground fault imbalance inside the static var generator is mapped according to the phase offset and the ground current mutation rate.

[0022] Based on the physical location of the fault imbalance, the ground fault load distribution imbalance area is determined using the internal electrical topology of the static var generator.

[0023] In a further implementation, the step of evaluating the electrical coupling stability of the fault area based on the electrical coupling correlation data between different components inside the static var generator, and obtaining the current electrical stability status and a list of key influencing components, includes:

[0024] Obtain the power transfer impedance between different components inside the static var generator located in the ground fault load distribution imbalance region;

[0025] The magnetic coupling coefficient is obtained by comparing the voltage change to the current change caused by magnetic coupling between different components inside the static var generator.

[0026] The power transmission impedance and the magnetic coupling coefficient are weighted and fused to obtain electrical coupling correlation data, and the change in electrical coupling correlation data between adjacent sampling periods is calculated.

[0027] The degree of electrical coupling fluctuation is obtained by summing the squares of the deviations between the change in electrical coupling correlation data and the average change in electrical coupling correlation data.

[0028] The electrical coupling fluctuation level is compared with a preset stability threshold to obtain an electrical stability comparison result, and the current electrical stability state is determined based on the electrical stability comparison result.

[0029] When the current electrical stability state is electrical instability, the components in the ground fault load distribution imbalance area are screened according to the degree of electrical coupling fluctuation, and a list of key influencing components is constructed.

[0030] In a further implementation, the step of dynamically adjusting the load distribution of the unbalanced area of ​​the ground fault load distribution based on the current electrical stability state and the list of key influencing components to obtain an optimized load distribution scheme includes: when the current electrical stability state is electrical instability, determining the dominant factors of electrical instability, and calculating a coordination factor based on the dominant factors of electrical instability;

[0031] Based on the list of key influencing components, obtain the key operating state vectors associated with each key influencing component within the ground fault load distribution imbalance area;

[0032] Calculate the deviation between the target reactive power setpoint and the actual reactive power data for each key influencing component to obtain the error signal;

[0033] Using the error signal and the coordination factor as inputs, the adjustment increment of the key operating state vector is calculated using the proportional-integral control method;

[0034] The adjustment increment is superimposed on the key operating state vector to obtain the key operating state optimization vector;

[0035] The reactive power output optimization amount of each key influencing component is determined by the key operating state optimization vector and real-time load allocation data, and the load allocation optimization scheme is determined based on the reactive power output optimization amount.

[0036] In a further implementation, the key operating state vector includes the pulse width modulation duty cycle, carrier frequency, and output voltage phase.

[0037] In a further implementation, the step of determining the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms includes:

[0038] Obtain the current operating status data of the power devices associated with each key influencing component, and calculate the real-time voltage change rate and real-time current change rate of the power devices associated with each key influencing component based on the current operating status data;

[0039] The average values ​​of the real-time voltage change rate and the real-time current change rate for all power devices are calculated to obtain the corresponding voltage rise rate and current change rate.

[0040] The similarity between the real-time waveform composed of the voltage rise rate and the current change rate and the typical ground fault waveform is calculated to obtain the waveform similarity.

[0041] When the waveform similarity is not less than the preset waveform similarity threshold, the coordination factor is used to correct the time of successful protection actions of the same type in the past to obtain the optimal protection action timing.

[0042] When the waveform similarity is less than the preset waveform similarity threshold, the standard protection delay is corrected using the waveform similarity to obtain the optimal protection action timing.

[0043] In a further implementation, the step of generating a set of protection action instructions based on the optimal protection action timing and the load allocation optimization scheme includes:

[0044] The load allocation optimization scheme is analyzed to extract the load allocation status of each key influencing component. Based on the load allocation status, a preset protection action priority mapping table is matched to extract the protection action priority corresponding to the load allocation status.

[0045] The coordination time interval parameter between adjacent protection actions is calculated based on the delay of the action time point associated with the load distribution state relative to the fault initiation time.

[0046] Using the protection action priority as the benchmark weight, the comprehensive priority index of each protection action is calculated by utilizing the load ratio of each component inside the static var generator in real time in the load allocation optimization scheme.

[0047] The protection actions in the load allocation optimization scheme are arranged in descending order according to the comprehensive priority index to form a protection action execution sequence, and the optimal protection action timing is taken as the action time of the first protection action in the protection action execution sequence.

[0048] Starting from the second protection action in the protection action execution sequence, the action time of the previous protection action is superimposed with the coordination time interval parameter corresponding to the current protection action to obtain the action time of the current protection action.

[0049] A set of protection action instructions is generated based on the protection action identifier and action time corresponding to each protection action in the protection action execution sequence.

[0050] Secondly, the present invention provides a ground fault protection system for a static var generator, the system comprising: a feature extraction module, used to extract zero-sequence ground current feature based on real-time three-phase current and voltage data during the operation of the static var generator;

[0051] The imbalance analysis module is used to determine the imbalance area of ​​the ground fault load distribution of the static var generator based on the zero-sequence ground current characteristics.

[0052] The stability analysis module is used to evaluate the electrical coupling stability of the fault area in the ground fault load distribution imbalance area based on the electrical coupling correlation data between different components inside the static var generator, and obtain the current electrical stability status and a list of key influencing components.

[0053] The load distribution module is used to dynamically adjust the load distribution in the ground fault load distribution imbalance area according to the current electrical stability status and the list of key influencing components, so as to obtain an optimized load distribution scheme.

[0054] The action analysis module is used to determine the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms.

[0055] The fault protection module is used to generate a set of protection action instructions based on the optimal protection action timing and the load distribution optimization scheme, and to use the set of protection action instructions to control the static var generator to perform ground fault protection.

[0056] Thirdly, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described method.

[0057] This invention provides a method, system, and medium for ground fault protection of a static var generator (SVR). The method extracts zero-sequence ground current characteristics based on real-time three-phase current and voltage data during SVR operation; determines the ground fault load distribution imbalance region of the SVR based on the zero-sequence ground current characteristics; assesses the electrical coupling stability of the fault region within the imbalance region based on electrical coupling correlation data between different components of the SVR, obtaining the current electrical stability state and a list of key influencing components; dynamically adjusts the load distribution in the imbalance region based on the current electrical stability state and the list of key influencing components, obtaining an optimized load distribution scheme; determines the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms; generates a protection action command set based on the optimal protection action timing and the optimized load distribution scheme, and uses the protection action command set to control the SVR for ground fault protection. Compared with existing technologies, this method accurately identifies faults and optimizes load distribution based on real-time operating data, enabling rapid, accurate, and orderly protection actions when the static var generator experiences a grounding fault. This effectively protects the static var generator, reduces fault losses, and ensures the safe and stable operation of the system. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the ground fault protection method for a static var generator provided in an embodiment of the present invention;

[0059] Figure 2 This is a block diagram of a static var generator ground fault protection system provided in an embodiment of the present invention.

[0060] Explanation of reference numerals in the attached figures: 101, Feature extraction module; 102, Imbalance analysis module; 103, Stability analysis module; 104, Load distribution module; 105, Action analysis module; 106, Fault protection module. Detailed Implementation

[0061] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0062] Figure 1 This is a schematic flowchart of a static var generator (SVM) ground fault protection method provided in an embodiment of the present invention. The present invention provides a method for protecting a static var generator from ground faults, such as... Figure 1 As shown, the method includes the following steps:

[0063] S1. Extract the zero-sequence grounding current characteristic quantity based on the real-time three-phase current and voltage data during the operation of the static var generator.

[0064] In some implementations, the step of extracting the zero-sequence grounding current characteristic quantity based on the real-time three-phase current and voltage data during the operation of the static var generator includes:

[0065] Real-time three-phase current and voltage data of each component inside the static var generator are collected in real time, and the real-time three-phase current and voltage data collected at the same sampling time are added together to obtain the instantaneous value of zero-sequence current.

[0066] The effective value of the zero-sequence current is obtained by performing an arithmetic average filter on the instantaneous value of the zero-sequence current within a single continuous power frequency cycle.

[0067] The absolute value of the difference between the effective values ​​of the zero-sequence current between two adjacent power frequency cycles is calculated based on the real-time three-phase current and voltage data to obtain the ground current mutation rate.

[0068] The system voltage phase information is obtained by real-time tracking of the phase change of the flexible AC transmission system voltage through a phase-locked loop synchronization system voltage phase.

[0069] The phase difference angle between the fundamental component of the grounding current and the zero-sequence component of the flexible AC transmission system voltage is calculated based on the system voltage phase information to obtain the phase offset.

[0070] The effective value of the zero-sequence current, the ground current mutation rate, and the phase offset are combined to form the zero-sequence ground current characteristic quantity.

[0071] Specifically, in this embodiment, high-precision current transformers and voltage transformers are installed at key electrical nodes of the static var generator. For example, in this embodiment, current transformers and voltage transformers can be installed at the input / output terminals of the power devices and the AC input side of the static var generator. The analog signals output by the current transformers and voltage transformers are sampled according to a set sampling frequency. The sampled analog quantities are converted into digital quantities to obtain real-time three-phase current and voltage data. In this embodiment, the collected real-time three-phase current and voltage data are preprocessed, such as by signal amplification and filtering, to improve the accuracy and reliability of the data, resulting in preprocessed three-phase current and voltage data. The preprocessed three-phase current and voltage data at the same sampling time are added together to obtain the corresponding instantaneous values ​​of the three-phase current and voltage. The instantaneous values ​​of the three-phase current and voltage are used as the instantaneous value of the zero-sequence current. In a normal symmetrical system, the sum of the instantaneous values ​​of the three-phase current is theoretically zero. However, when a ground fault occurs, the instantaneous value of the zero-sequence current can reflect the magnitude and direction of the fault current.

[0072] Then, in this embodiment, the instantaneous values ​​of the zero-sequence current within a single consecutive power frequency cycle are subjected to arithmetic mean filtering to obtain the effective value of the zero-sequence current. Specifically, in this embodiment, the N instantaneous values ​​of the zero-sequence current within a single power frequency cycle are added together and divided by the number of sampling points in that cycle to obtain the average value of the zero-sequence current within that power frequency cycle. Then, the average value of the zero-sequence current within that power frequency cycle is squared to obtain the square average value of the zero-sequence current. Finally, the square root of the square average value of the zero-sequence current is taken to obtain the effective value of the zero-sequence current. This can eliminate the DC component and high-frequency harmonic components in the zero-sequence current, resulting in a more effective value. The accurate effective value of the zero-sequence current reflects the actual amplitude of the zero-sequence current. Simultaneously, this embodiment calculates the ground current mutation rate by determining the absolute value of the difference between the effective value of the zero-sequence current in the current power frequency cycle and the effective value of the zero-sequence current in the previous power frequency cycle, and by calculating the ratio of the absolute value of the difference between the effective values ​​of the zero-sequence current in two adjacent power frequency cycles to the rated value of the zero-sequence current. The ground current mutation rate reflects the degree of change of the zero-sequence current between adjacent power frequency cycles. When the ground current mutation rate exceeds a set threshold, it may indicate that a ground fault has occurred in the static var generator.

[0073] A phase-locked loop (PLL) is a common synchronous circuit. A PLL typically consists of three parts: a phase detector, a loop filter, and a voltage-controlled oscillator (VCO). It can track the phase of the voltage in a flexible AC transmission system in real time. The phase detector compares the input system voltage signal (i.e., the processed three-phase voltage signal collected from the grid connection point) with the signal output from the VCO. The phase detector detects the phase difference between the two signals and generates an error signal proportional to the phase difference. The loop filter processes the error signal output from the phase detector, removing high-frequency noise and interference components to make the signal smoother and more stable. The filtered signal is then used as a control signal to adjust the voltage. The voltage-controlled oscillator (VCO) outputs a signal that adjusts its frequency and phase based on the control signal from the loop filter. Through continuous adjustment, the VCO output signal is synchronized with the input system voltage signal, achieving phase locking. After the phase-locked loop (PLL) stabilizes, the phase of the VCO output signal represents the positive-sequence phase of the system voltage fundamental. Therefore, in this embodiment, the flexible AC transmission system voltage is connected to the PLL circuit. The PLL, through phase comparison, filtering, and the VCO, synchronizes the internally generated signal phase with the system voltage phase. This embodiment uses the three-phase voltage signals from the static var generator (SVA) grid connection point. The three-phase voltage signals are phase A, phase B, and phase C, and the three-phase voltages are... The signal is decomposed to obtain its positive-sequence, negative-sequence, and zero-sequence components. A phase-locked loop (PLL) tracks the positive-sequence phase of the system voltage fundamental in real time, outputting the positive-sequence phase angle value. This angle value reflects the phase change of the positive-sequence component in real time. In this embodiment, the positive-sequence phase angle value is used as the real-time phase information of the system voltage. Since the zero-sequence component is one of the symmetrical components of the three-phase voltage, together with the positive and negative-sequence components, it constitutes the three-phase voltage system. Under normal circumstances, the positive-sequence components of the three-phase voltage are 120 degrees out of phase, while the three phases of the zero-sequence component are in phase. However, in the event of a ground fault or other asymmetrical fault, the phase of the zero-sequence component may change. Therefore… In this embodiment, the positive-sequence phase angle value of the system voltage fundamental wave obtained through the phase-locked loop can be used as the reference phase. Then, the phase angle of the zero-sequence component is extracted by performing symmetrical component decomposition calculation on the three-phase voltage. Symmetrical component decomposition is a method of decomposing the three-phase voltage into positive-sequence, negative-sequence, and zero-sequence components. Its basic principle is based on the symmetry of the three-phase system. During the decomposition process, the three-phase voltage is converted into the phasor form of the corresponding positive-sequence, negative-sequence, and zero-sequence components. The phase angle of the zero-sequence component can be obtained by calculating the angle between the zero-sequence component phasor and the reference direction. For example, the positive direction of the A-phase voltage can be selected as the reference direction, and then the angle difference between the zero-sequence component phasor and the reference direction can be calculated. This angle difference is the phase angle of the zero-sequence component.

[0074] Finally, this embodiment performs a Fourier transform on the instantaneous value of the zero-sequence current to filter out the harmonic components in the zero-sequence current and extract the phase angle of the fundamental component of the zero-sequence current. The fundamental component of the zero-sequence current is marked as the fundamental component of the grounding current. In this embodiment, the phase angle of the zero-sequence component of the system voltage and the phase angle of the fundamental component of the grounding current are subtracted to obtain the phase offset. For example, in this embodiment, the fundamental component of the grounding current and the zero-sequence component of the system voltage are converted into phasor form respectively, and the angle between the two phasors is calculated. This phase difference angle is the phase offset. The phase offset reflects the phase relationship between the fundamental component of the grounding current and the zero-sequence component of the system voltage. In this embodiment, the three parameters of the effective value of the zero-sequence current, the abrupt change rate of the grounding current, and the phase offset are arranged in a certain order to form a zero-sequence grounding current characteristic quantity containing multiple elements. The zero-sequence grounding current characteristic quantity comprehensively reflects the magnitude, trend of change, and phase characteristics of the zero-sequence current during a grounding fault, providing a basis for subsequent fault judgment and protection actions.

[0075] S2. Based on the zero-sequence grounding current characteristics, determine the grounding fault load distribution imbalance area of ​​the static var generator.

[0076] In some embodiments, the step of determining the ground fault load distribution imbalance region of the static var generator based on the zero-sequence ground current characteristics includes:

[0077] The effective value of the zero-sequence current is compared with a preset ground fault threshold. When the effective value of the zero-sequence current exceeds the preset ground fault threshold, the physical location of the ground fault imbalance inside the static var generator is mapped according to the phase offset and the ground current mutation rate.

[0078] Based on the physical location of the fault imbalance, the ground fault load distribution imbalance area is determined using the internal electrical topology of the static var generator.

[0079] Specifically, the phase offset reflects the phase relationship between the fundamental component of the ground current and the zero-sequence component of the system voltage. Different fault locations lead to different phase offsets. For example, when a fault occurs near a specific power device in a static var generator, the change in the electrical characteristics of that power device will cause a change in the phase of the ground current, thus altering the phase offset. The ground current abrupt change rate reflects the degree of change of the zero-sequence current within adjacent power frequency cycles. The closer the fault location is to the measurement point, the more direct the impact on the zero-sequence current, and the greater the abrupt change rate may be. Furthermore, the different mechanisms by which faults at different locations affect the system will also lead to different characteristics in the abrupt change rate. This embodiment pre-emptively uses large... The experiment and simulation establish a mapping table between phase offset, ground current mutation rate and the physical location of the fault imbalance inside the static var generator. In actual operation, this embodiment compares the effective value of the zero-sequence current with the preset ground fault threshold. When the effective value of the zero-sequence current exceeds the preset ground fault threshold, it can be preliminarily determined that the static var generator may have a ground fault. Then, based on the phase offset and ground current mutation rate obtained in real time, the mapping table is searched to determine the physical location of the ground fault imbalance inside the static var generator. For example, this embodiment can set different combinations of phase offset and mutation rate to correspond to different power device numbers or electrical connection point locations.

[0080] The internal electrical topology of a static var generator (SVR) describes the electrical connections and energy flow paths between its various components. For example, the SVR's internal electrical topology includes various power modules, reactors, capacitors, transformers, and other components, as well as their electrical connections. In this embodiment, the location of the fault imbalance is mapped onto the SVR's internal electrical topology. The electrical connections and load distribution around this location are analyzed. A fault may alter the electrical parameters of the fault area and its related components, such as impedance and admittance, thereby affecting power distribution. This embodiment analyzes the changes in these electrical parameters and their positional relationships within the topology to determine which areas will experience load imbalance due to the fault. For instance, if a fault occurs near a power device, the fault in that device may cause power distribution imbalances on the connected DC or AC buses. Changes in the static var generator (SVA) can identify the unbalanced load distribution area during a ground fault. This area may include the faulty power device itself and other components in the SVA that are directly electrically connected to it. This provides accurate target area information for subsequent fault handling and protection actions, helping to improve the targeting and effectiveness of SVA ground fault protection. For example, this embodiment assumes that the SVA consists of multiple power units, each containing several power devices. When the effective value of the zero-sequence current exceeds the ground fault threshold, analysis of the phase offset and ground current mutation rate reveals that the fault may occur in the middle of a certain power unit. This embodiment can further analyze the internal electrical topology of the SVA to determine the load transfer or uneven distribution among the power devices in this area, thereby identifying the unbalanced load distribution area during a ground fault composed of this power device and its adjacent preceding and following power devices.

[0081] S3. In the ground fault load distribution imbalance area, the electrical coupling stability of the fault area is evaluated based on the electrical coupling correlation data between different components inside the static var generator, and the current electrical stability status and a list of key influencing components are obtained.

[0082] In some implementations, the step of assessing the electrical coupling stability of the fault area based on the electrical coupling correlation data between different components inside the static var generator, and obtaining the current electrical stability status and a list of key influencing components, includes:

[0083] Obtain the power transfer impedance between different components inside the static var generator located in the ground fault load distribution imbalance region;

[0084] The magnetic coupling coefficient is obtained by comparing the voltage change to the current change caused by magnetic coupling between different components inside the static var generator.

[0085] The power transmission impedance and the magnetic coupling coefficient are weighted and fused to obtain electrical coupling correlation data, and the change in electrical coupling correlation data between adjacent sampling periods is calculated.

[0086] The degree of electrical coupling fluctuation is obtained by summing the squares of the deviations between the change in electrical coupling correlation data and the average change in electrical coupling correlation data.

[0087] The electrical coupling fluctuation level is compared with a preset stability threshold to obtain an electrical stability comparison result, and the current electrical stability state is determined based on the electrical stability comparison result.

[0088] When the current electrical stability state is electrical instability, the components in the ground fault load distribution imbalance area are screened according to the degree of electrical coupling fluctuation, and a list of key influencing components is constructed.

[0089] Specifically, in the ground fault load distribution imbalance area of ​​the static var generator, there are power transmission relationships between its various components. Power transmission impedance is an important parameter for measuring the ease of power transmission between these components. In this embodiment, high-precision impedance measurement devices are installed inside the static var generator for key nodes of different components in the ground fault load distribution imbalance area, such as power modules, DC buses, and AC buses. These impedance measurement devices should have wideband measurement capabilities to accurately capture impedance characteristics at different frequencies. In this embodiment, an AC signal of a specific frequency and amplitude is injected into the component under test, and the voltage and current across the component are measured simultaneously. According to Ohm's law, power transmission impedance is equal to the ratio of the effective voltage value to the effective current value. Specifically, after measuring the effective voltage and current values, this embodiment divides the effective voltage value by the effective current value to obtain the power transmission impedance of the component at a specific frequency. These power transmission impedances reflect the degree of mutual influence between different components during power transmission.

[0090] Inside a static var generator (SVM), magnetic coupling exists between different components. When current flows through a component with magnetic parts (such as reactors or transformers), a magnetic field is generated around it, which in turn affects other components magnetically coupled to it, causing changes in voltage and current on these components. This magnetic coupling phenomenon reflects the strength of electromagnetic interaction between components. In actual operation, a known current change is applied to components in the load imbalance area of ​​a ground fault. Simultaneously, this embodiment uses a high-precision voltage measuring device to measure the voltage change caused by magnetic coupling in adjacent components. The magnetic coupling coefficient is equal to the ratio of the voltage change to the current change caused by magnetic coupling. This embodiment obtains more accurate magnetic coupling characteristics by repeatedly measuring the current change and corresponding voltage change under different conditions and calculating the corresponding magnetic coupling coefficient. The magnetic coupling coefficient reflects the tightness of this magnetic coupling and can characterize the strength of the mutual coupling between two components through a magnetic field.

[0091] The power transmission impedance and magnetic coupling coefficient reflect the electrical coupling relationship between the internal components of the static var generator from two different aspects: power transmission and magnetic field coupling, respectively. Considering the different importance of power transmission impedance and magnetic coupling coefficient in reflecting electrical coupling characteristics, this embodiment assigns them different weights. If the power transmission impedance has a greater impact on system stability, it can be assigned a higher weight. For example, the weight of power transmission impedance is 0.6, and the weight of magnetic coupling coefficient is 0.4. In this embodiment, the power transmission impedance and magnetic coupling coefficient are weighted and summed to obtain electrical coupling correlation data. The electrical coupling correlation data is collected periodically according to a set sampling frequency. In two adjacent sampling periods, two electrical coupling correlation data values ​​are obtained respectively. The electrical coupling correlation data value of the next sampling period is subtracted from the value of the previous sampling period to obtain the change in electrical coupling correlation data between adjacent sampling periods. This change can reflect the electrical coupling relationship. The dynamic changes of the electrical coupling correlation data between adjacent sampling periods are observed. Next, this embodiment calculates the arithmetic mean of the collected electrical coupling correlation data changes over a period of time (e.g., multiple sampling periods) to obtain the average value of the electrical coupling correlation data changes. For each electrical coupling correlation data change, the difference between it and the average value is calculated to obtain the electrical coupling correlation data deviation value. Then, the sum of squares is calculated for each electrical coupling correlation data deviation value to obtain the degree of electrical coupling fluctuation. The degree of electrical coupling fluctuation can quantify the severity of the changes in electrical coupling correlation data; the larger the value, the more unstable the changes in electrical coupling correlation data. It should be noted that the stability threshold is determined based on the degree of electrical coupling fluctuation and the allowable fluctuation range when the static var generator is operating normally, ensuring that the degree of electrical coupling fluctuation will not exceed this stability threshold under normal conditions, and that it can be reliably detected when the system exhibits an unstable trend.

[0092] This embodiment compares the calculated electrical coupling fluctuation level with a preset stability threshold in real time. If the electrical coupling fluctuation level is less than the preset stability threshold, the current electrical stability state is determined to be stable. If the electrical coupling fluctuation level is greater than or equal to the preset stability threshold, the current electrical stability state is determined to be unstable. This comparison process can quickly determine the electrical coupling stability of the fault area inside the static var generator. Specifically, for each component in the ground fault load distribution imbalance area, this embodiment filters each component in the ground fault load distribution imbalance area according to the magnitude of the electrical coupling fluctuation level. For example, the components can be arranged in descending order of electrical coupling fluctuation level, and the first few components with larger electrical coupling fluctuation levels can be selected as key influencing components. The key influencing components are then arranged in descending order of influence to construct a list of key influencing components. The list of key influencing components can clearly show which components have the greatest impact on the electrical coupling stability of the entire fault area under the condition of electrical instability, thereby improving the efficiency and accuracy of fault handling.

[0093] S4. Based on the current electrical stability status and the list of key influencing components, dynamically adjust the load distribution in the ground fault load distribution imbalance area to obtain an optimized load distribution scheme.

[0094] In some implementations, the step of dynamically adjusting the load distribution of the unbalanced area of ​​the ground fault load distribution based on the current electrical stability state and the list of key influencing components to obtain an optimized load distribution scheme includes: when the current electrical stability state is electrical instability, determining the dominant factors of electrical instability, and calculating a coordination factor based on the dominant factors of electrical instability;

[0095] Based on the list of key influencing components, obtain the key operating state vectors associated with each key influencing component within the ground fault load distribution imbalance area; the key operating state vectors include pulse width modulation duty cycle, carrier frequency, and output voltage phase; calculate the degree of deviation between the target reactive power setpoint and the actual reactive power data for each key influencing component to obtain the error signal;

[0096] Using the error signal and the coordination factor as inputs, the adjustment increment of the key operating state vector is calculated using the proportional-integral control method;

[0097] The adjustment increment is superimposed on the key operating state vector to obtain the key operating state optimization vector;

[0098] The reactive power output optimization amount of each key influencing component is determined by the key operating state optimization vector and real-time load allocation data, and the load allocation optimization scheme is determined based on the reactive power output optimization amount.

[0099] When electrical instability is detected as the current electrical stability state, this embodiment performs statistical analysis based on the instability type identifiers recorded in the list of key influencing components. Specifically, if the number of components in the magnetic saturation aggravation category exceeds 50%, it is classified as magnetic saturation-dominated instability; if the number of components in the electrical decoupling category exceeds 60%, it is classified as impedance imbalance-dominated instability; if the number of both magnetic saturation-dominated and impedance imbalance-dominated instability exceeds 40%, it is classified as mixed instability. This yields the classification result of the dominant factors in electrical instability. For the magnetic saturation-dominated instability classification result, this embodiment calculates the ratio of the difference between the saturation magnetic flux and the current magnetic flux to the saturation magnetic flux, obtaining the magnetic flux margin percentage of the unsaturated component. The magnetic flux margin percentage refers to the percentage of the component's magnetic flux margin under the current operating state. The remaining proportion of magnetic flux from saturation flux is determined by finding the minimum magnetic flux margin percentage (i.e., the component closest to saturation) among all unsaturated components. This minimum percentage is multiplied by a preset magnetic flux margin threshold as a coordination factor. For impedance imbalance-dominated instability classification results, this embodiment calculates the ratio of the difference between the rated current upper limit and the current of each component to the rated current upper limit, obtaining the current margin percentage of healthy components. The current margin percentage refers to the remaining proportion of the current from the rated current upper limit of a component in its current operating state. In this embodiment, the current margin percentages of all healthy components are added together and divided by the number of healthy components to obtain the average current margin. This average current margin is multiplied by a preset current margin threshold as a coordination factor. For mixed instability, this embodiment takes the weighted average of the calculation results for magnetic circuit saturation-dominated instability and impedance imbalance-dominated instability as the coordination factor.

[0100] During the operation of the static var generator (SVR), this embodiment collects key operating state vectors of each critical component in real time. These vectors may include data such as pulse width modulation (PWM) duty cycle, carrier frequency, and output voltage phase. The PWM duty cycle represents the percentage of the power device's on-time within the cycle; the carrier frequency represents the switching frequency of the power semiconductor device; and the output voltage phase represents the phase difference angle between the power unit's output voltage and the grid reference voltage. This embodiment then calculates the absolute deviation between the target reactive power setpoint and the real-time collected actual reactive power data for each critical component. The absolute deviation is divided by the component's rated capacity to obtain the normalized power deviation rate. This normalized power deviation rate is used as the error signal. Proportional-integral (PI) control works by proportionally summing the error signal. Integral operations yield the adjustment increment of the control quantity. The proportional term can quickly respond to changes in the error signal, while the integral term can eliminate the steady-state error of the system. Specifically, in this embodiment, the error signal is multiplied by a preset proportional coefficient to obtain the proportional term. The proportional coefficient can be adjusted according to the dynamic response characteristics of the system and the control requirements. For example, if it is desired that the system can quickly respond to changes in the error signal, the proportional coefficient can be appropriately increased. At the same time, in this embodiment, the historical cumulative value of the error signal is multiplied by the integral coefficient to obtain the integral term. Integral operations can accumulate historical information of the error signal, thereby eliminating the steady-state error of the system. In this embodiment, the proportional term and the integral term are added and multiplied by a coordination factor to coordinate the control effects between different key influencing components, thereby obtaining the adjustment increment of the key operating state vector.

[0101] For each critically affected component, this embodiment superimposes the pulse width modulation duty cycle, carrier frequency, and output voltage phase from its critical operating state vector with the calculated corresponding adjustment increments. Specifically, this embodiment superimposes the duty cycle adjustment increment onto the original pulse width modulation duty cycle value, the frequency adjustment increment onto the original carrier frequency value, and the phase adjustment increment onto the original output voltage phase value. Simultaneously, parameter safety boundary checks are performed during the superposition process. These checks include maintaining the duty cycle within the 0% to 100% effective range, ensuring the carrier frequency variation does not exceed ±15% of the rated value, and guaranteeing that the phase offset conforms to the grid synchronization phase-locked loop range. This yields a critical operating state that meets safety constraints. This embodiment first transforms the vector, and then, based on the key operating state optimization vector, calculates the optimized reactive power output of each key influencing component through physical characteristic mapping relationships. Specifically, in the physical characteristics of the static var generator (SVM), the change in pulse width modulation (PWM) duty cycle directly affects the amplitude and waveform of the output voltage, and thus affects the reactive power output. Specifically, the higher the duty cycle, the greater the amplitude of the output voltage, and under certain grid voltage conditions, the more reactive power can be provided. This embodiment determines the basic output based on the optimized PWM duty cycle value in the key operating state optimization vector, according to the direct proportional relationship between duty cycle and reactive power output. Simultaneously, this embodiment establishes the characteristic relationship between switching losses and reactive power output through experiments and system analysis. The curve, representing the relationship between switching losses and reactive power output, reflects the impact of switching losses on reactive power output at different carrier frequencies. Generally, changes in carrier frequency affect the switching losses of switching devices, thus affecting the actual reactive power output. In this embodiment, the optimized carrier frequency value in the key operating state optimization vector is substituted into the switching loss-output characteristic curve to obtain the loss value at that carrier frequency. Then, the base output is compensated based on the loss value. The base output is superimposed with the loss value to obtain the compensated base output, thus offsetting the impact of switching losses on reactive power output. Simultaneously, the phase difference between the output voltage phase and the grid voltage phase directly affects the power factor of the static var generator; the larger the phase difference, the lower the power factor. The lower the power factor, the higher the ratio of reactive power output to active power output. This embodiment constructs a correlation model between the output voltage phase difference and the power factor. This correlation model describes the impact of phase difference changes on the power factor, which in turn affects the effectiveness of reactive power output. Generally speaking, the larger the phase difference, the lower the power factor, and the more the effective output of reactive power will be affected. In this embodiment, the output voltage phase correction value in the key operating state optimization vector is substituted into the phase difference-power factor correlation model to obtain the corresponding power factor change data. The power factor change data is multiplied by the compensated base output to correct the compensated base output through the power factor change data, thus obtaining the final optimized reactive power output.

[0102] This embodiment collects real-time load distribution data from the static var generator (SVR). This data includes the current reactive power output of each component and the total reactive power demand of the system. This data reflects the current load demand and operating status of the system. This embodiment uses the real-time load distribution data to correct the calculated reactive power output optimization. By comparing and analyzing the real-time data with the calculation results, the optimized reactive power output is adjusted. For example, if the calculated optimized reactive power output is an increase of 10 kvar, but the real-time load distribution data shows that the system currently has excess reactive power, then the optimized reactive power output needs to be adjusted. The increase can be reduced. Based on the real-time load distribution data, the optimized reactive power output is corrected from an increase of 10 kvar to an increase of 5 kvar to better match the actual needs of the system. Next, this embodiment addresses all key influencing components... The reactive power output optimizations of each component are summed to obtain the total system output. Based on the proportion of the reactive power output optimization of each key influencing component to the total system output, the proportion of each component in the load distribution is calculated to obtain the load distribution ratio. For example, the reactive power output optimization of each component is divided by the sum of the reactive power output optimizations of all components to obtain the load ratio of that component. The current electrical stability status is evaluated. When the electrical instability index exceeds the severe threshold, the circuit breaker trip command is automatically associated. When an abnormal temperature gradient of a key component is detected, forced load reduction protection is triggered. Or when the circulating current component ratio exceeds the limit, a circulating current suppression control sequence is generated. In this embodiment, the protection action command is associated and mapped with the load ratio to generate a load distribution optimization scheme. The load distribution optimization scheme includes the load distribution status, that is, the load ratio of each key influencing component, to achieve load distribution optimization and improve the stability and reliability of the system.

[0103] S5. Determine the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms.

[0104] In some implementations, the step of determining the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms includes:

[0105] Obtain the current operating status data of the power devices associated with each key influencing component, and calculate the real-time voltage change rate and real-time current change rate of the power devices associated with each key influencing component based on the current operating status data;

[0106] The average values ​​of the real-time voltage change rate and the real-time current change rate for all power devices are calculated to obtain the corresponding voltage rise rate and current change rate.

[0107] The similarity between the real-time waveform composed of the voltage rise rate and the current change rate and the typical ground fault waveform is calculated to obtain the waveform similarity.

[0108] When the waveform similarity is not less than the preset waveform similarity threshold, the coordination factor is used to correct the time of successful protection actions of the same type in the past to obtain the optimal protection action timing.

[0109] When the waveform similarity is less than the preset waveform similarity threshold, the standard protection delay is corrected using the waveform similarity to obtain the optimal protection action timing.

[0110] Specifically, during the operation of the static var generator (SVR), this embodiment uses sensors installed on the power devices associated with each key influencing component to collect real-time data on the current operating status of these power devices. These sensors can accurately measure the voltage across the power devices and the current flowing through them. For example, for IGBT (Insulated Gate Bipolar Transistor) power devices, the sensors can measure their collector-emitter voltage and collector current respectively. After acquiring the current operating status data, this embodiment uses the ratio of the difference between adjacent data points to the time interval to calculate the real-time voltage change rate and the real-time current change rate. Specifically, assuming at time t... At time t1 and t2 (t2 > t1), the voltages of the power devices are collected as U1 and U2, and the currents are collected as I1 and I2, respectively. The time interval is Δt = t2 - t1. The real-time voltage change rate can be expressed as (U2 - U1) divided by Δt, and the real-time current change rate can be expressed as the ratio of (I2 - I1) to Δt. Thus, the real-time voltage change rate and real-time current change rate of each power device are obtained. Then, in this embodiment, the real-time voltage change rates of all power devices are added together and divided by the total number of power devices to obtain the voltage rise rate. Similarly, the real-time current change rates of all power devices are added together and divided by the total number of power devices to obtain the current change rate.

[0111] This embodiment constructs a real-time waveform using voltage rise rate and current change rate as the horizontal and vertical axes. For example, the voltage rise rate is used as the horizontal axis value and the current change rate as the vertical axis value. Corresponding points are marked on the coordinate system, and these points are connected in chronological order to form the real-time waveform. The constructed real-time waveform is compared with a pre-stored typical ground fault waveform. The sum of squares of the differences between the two waveform data points is divided by the sum of squares of the typical waveform data points to obtain the waveform similarity. The smaller the sum of squares, the closer the real-time waveform is to the typical waveform, and the higher the waveform similarity. Waveform similarity measures the degree of similarity between the real-time waveform and the typical waveform. Simultaneously, during system operation, this embodiment records the historical successful protection action times of the same type. This data is stored in the system's database and can be retrieved through query operations. When the waveform similarity is not less than a preset waveform similarity threshold, it is determined that the current fault is highly similar to a typical ground fault, and protection actions must be taken promptly. At this time, this embodiment uses the previously calculated coordination factor to adjust the historical successful protection action times of the same type. The correction method involves multiplying the successful protection action time of the same type in history by a coordination factor. This corrected time is the optimal protection action timing. Simultaneously, this embodiment sets a standard protection delay during system design. The standard protection delay is the time required for the protection device to execute a protection action from detecting a fault without special correction; it serves as the benchmark time for the protection system design. When the waveform similarity is less than a preset waveform similarity threshold, it indicates that the fault characteristics are not obvious or differ significantly from typical faults. In this case, the standard delay is adjusted using waveform similarity. This embodiment uses the calculated waveform similarity to correct the standard protection delay by multiplying the standard protection delay by the waveform similarity. This corrected time is the optimal protection action timing. The lower the waveform similarity, the longer the corrected delay, avoiding premature action due to misjudgment and ensuring the reliability of the protection action. Through the above steps, this embodiment accurately determines the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms, achieving accurate and timely protection against static var generator ground faults.

[0112] S6. Generate a set of protection action instructions based on the optimal protection action timing and the load allocation optimization scheme, and use the set of protection action instructions to control the static var generator for ground fault protection.

[0113] In some implementations, the step of generating a set of protection action instructions based on the optimal protection action timing and the load allocation optimization scheme includes:

[0114] The load allocation optimization scheme is analyzed to extract the load allocation status of each key influencing component. Based on the load allocation status, a preset protection action priority mapping table is matched to extract the protection action priority corresponding to the load allocation status.

[0115] The coordination time interval parameter between adjacent protection actions is calculated based on the delay of the action time point associated with the load distribution state relative to the fault initiation time.

[0116] Using the protection action priority as the benchmark weight, the comprehensive priority index of each protection action is calculated by utilizing the load ratio of each component inside the static var generator in real time in the load allocation optimization scheme.

[0117] The protection actions in the load allocation optimization scheme are arranged in descending order according to the comprehensive priority index to form a protection action execution sequence, and the optimal protection action timing is taken as the action time of the first protection action in the protection action execution sequence.

[0118] Starting from the second protection action in the protection action execution sequence, the action time of the previous protection action is superimposed with the coordination time interval parameter corresponding to the current protection action to obtain the action time of the current protection action.

[0119] A set of protection action instructions is generated based on the protection action identifier and action time corresponding to each protection action in the protection action execution sequence.

[0120] Specifically, the load allocation optimization scheme includes the load ratio of each key influencing component. This embodiment analyzes the load allocation optimization scheme to extract the load allocation status of each key influencing component, including the load ratio of each component. Simultaneously, this embodiment pre-sets a protection action priority mapping table in the system. This table records the correspondence between different load allocation ranges and protection action priorities. For example, a load ratio between 30% and 50% corresponds to medium priority, 50% to 70% to high priority, and below 30% to low priority. Based on the load allocation status of each key influencing component extracted from the load allocation optimization scheme, the system... The protection action priority mapping table is searched and matched to extract the protection action priority corresponding to each critically affected component. In this embodiment, each protection action has a preset action time point. This time point has a delay amount relative to the fault start time (the delay requirement relative to the fault start time). The delay amount can be calculated by multiplying the base delay coefficient by the inverse of the load ratio. Assuming there are two adjacent critically affected components, the delay amount of the action time point corresponding to the load distribution state of the first critically affected component is t3, and the delay amount of the action time point corresponding to the load distribution state of the second critically affected component is t4. Then the coordination time interval parameter between these two adjacent protection actions is (t4-t3).

[0121] In this embodiment, the extracted protection action priority is used as the base weight. For example, the base weight corresponding to the first priority is 3, the base weight corresponding to the second priority is 2, and the base weight corresponding to the third priority is 1. The real-time load ratio of each component inside the static var generator is obtained from the load distribution optimization scheme. The load ratio is calculated by dividing the reactive power output optimization amount of each component by the sum of the reactive power output optimization amounts of all components. The comprehensive priority index of each protection action is calculated using the load ratio and the base weight. The comprehensive priority index is calculated by multiplying the load ratio by the base weight. The protection actions in the load distribution optimization scheme are arranged in descending order of comprehensive priority index, and the protection action with the highest comprehensive priority index is placed at the beginning of the sequence, and so on, to form the protection action execution sequence.

[0122] In this embodiment, the protection action time of the first power device in the execution sequence is set as the fault start time in the optimal protection action timing plus the delay of the first power device's protection action. Starting from the second protection action in the protection action execution sequence, the action time of the previous protection action is added to the coordination time interval parameter corresponding to the current protection action to obtain the action time of the current protection action. For example, if the action time of the first protection action is t5, and the coordination time interval parameter corresponding to the first and second protection actions is ΔT, then the action time of the second protection action is t6 = t5 + ΔT. Based on the protection action identifier and action time corresponding to each protection action in the protection action execution sequence, a protection action instruction set is generated. The protection action identifier is used to uniquely identify each protection action, such as "circuit breaker trip" or "adjust power". The device parameters, etc., are used to determine the execution time of each protection action. In this embodiment, the protection action identifier and the action time are stored in the instruction set according to a certain format (such as key-value pairs in a data structure). For example, the instruction set can be a list, where each element contains a protection action identifier and the corresponding action time. When the action execution time arrives, an instruction is issued to the static var generator controller, enabling the protection system to achieve fast, accurate, and selective fault isolation under complex operating conditions. This embodiment can generate an accurate and orderly protection action instruction set based on the optimal protection action timing and load distribution optimization scheme, ensuring that the static var generator can coordinate and orderly execute each protection action under ground fault conditions, minimizing the impact of the fault on the equipment and system, and improving the safety and stability of the system.

[0123] This invention provides a method for ground fault protection of a static var generator (SVR). The method extracts zero-sequence ground current characteristics based on real-time three-phase current and voltage data during SVR operation; determines the ground fault load distribution imbalance region of the SVR based on the zero-sequence ground current characteristics; assesses the electrical coupling stability of the fault region within the imbalance region based on electrical coupling correlation data between different components of the SVR, obtaining the current electrical stability state and a list of key influencing components; dynamically adjusts the load distribution in the imbalance region based on the current electrical stability state and the list of key influencing components, obtaining an optimized load distribution scheme; determines the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms; generates a protection action command set based on the optimal protection action timing and the optimized load distribution scheme, and uses the protection action command set to control the SVR for ground fault protection. Compared with existing technologies, this method accurately identifies ground fault areas by using zero-sequence current characteristics. Combined with electrical coupling stability assessment and dynamic load adjustment, it enables rapid, accurate, and orderly protection actions when the static var generator experiences a ground fault. This achieves rapid fault isolation and stable system recovery, effectively suppresses fault propagation, and ensures the safe operation of the static var generator, thereby improving the reliability and safety of the power system.

[0124] It should be noted that the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0125] In one embodiment, such as Figure 2 As shown, this embodiment of the invention provides a ground fault protection system for a static var generator, the system comprising:

[0126] Feature extraction module 101 is used to extract zero-sequence grounding current features based on real-time three-phase current and voltage data during the operation of the static var generator.

[0127] The imbalance analysis module 102 is used to determine the imbalance area of ​​the ground fault load distribution of the static var generator based on the zero-sequence ground current characteristics.

[0128] Stability analysis module 103 is used to evaluate the electrical coupling stability of the fault area in the ground fault load distribution imbalance area based on the electrical coupling correlation data between different components inside the static var generator, and obtain the current electrical stability status and a list of key influencing components.

[0129] The load distribution module 104 is used to dynamically adjust the load distribution in the ground fault load distribution imbalance area according to the current electrical stability status and the list of key influencing components, so as to obtain an optimized load distribution scheme;

[0130] Action analysis module 105 is used to determine the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms;

[0131] The fault protection module 106 is used to generate a set of protection action instructions based on the optimal protection action timing and the load distribution optimization scheme, and to use the set of protection action instructions to control the static var generator to perform ground fault protection.

[0132] For specific limitations regarding a static var generator (SVM) ground fault protection system, please refer to the above-described limitations regarding a SVM ground fault protection method, which will not be repeated here. Those skilled in the art will recognize that the various modules and steps described in conjunction with the embodiments disclosed in this application can be implemented in hardware, software, or a combination of both. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0133] This invention provides a ground fault protection system for a static var generator (SVR). The system's feature extraction module extracts zero-sequence ground current characteristics based on real-time three-phase current and voltage data during SVR operation. An imbalance analysis module determines the ground fault load distribution imbalance region of the SVR based on the zero-sequence ground current characteristics. A stability analysis module evaluates the electrical coupling stability of the fault region within the imbalanced load distribution region based on electrical coupling correlation data between different components within the SVR, obtaining the current electrical stability state and a list of key influencing components. A load allocation module dynamically adjusts the load allocation in the imbalanced ground fault load distribution region based on the current electrical stability state and the list of key influencing components, obtaining an optimized load allocation scheme. An action analysis module determines the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms. A fault protection module generates a protection action command set based on the optimal protection action timing and the optimized load allocation scheme, and uses the protection action command set to control the SVR for ground fault protection. Compared with existing technologies, this system accurately identifies ground fault areas by using zero-sequence current characteristics. Combined with electrical coupling stability assessment and dynamic load adjustment, it enables rapid, accurate, and orderly protection actions when the static var generator experiences a ground fault. This allows for rapid fault isolation and stable system recovery, effectively suppressing fault propagation and ensuring the safe operation of the static var generator, thereby improving the reliability and safety of the power system.

[0134] In one embodiment, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0135] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., SSD, etc.).

[0136] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed, it can include the processes of the embodiments of the above methods.

[0137] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the technical principles of this invention, and these improvements and substitutions should also be considered within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the scope of the claims.

Claims

1. A method for protecting a static var generator from ground faults, characterized in that, Includes the following steps: Based on the real-time three-phase current and voltage data during the operation of the static var generator, the zero-sequence grounding current characteristic quantity is extracted. Based on the zero-sequence grounding current characteristics, determine the grounding fault load distribution imbalance area of ​​the static var generator; In the ground fault load distribution imbalance area, the electrical coupling stability of the fault area is evaluated based on the electrical coupling correlation data between different components inside the static var generator, and the current electrical stability status and a list of key influencing components are obtained. Based on the current electrical stability status and the list of key influencing components, the load distribution in the ground fault load distribution imbalance area is dynamically adjusted to obtain an optimized load distribution scheme. Based on real-time voltage and current change rate data and typical ground fault waveforms, determine the optimal protection action timing; Based on the optimal protection action timing and the load allocation optimization scheme, a protection action instruction set is generated, and the protection action instruction set is used to control the static var generator to perform ground fault protection.

2. The method for ground fault protection of a static var generator as described in claim 1, characterized in that, The step of extracting the zero-sequence grounding current characteristic quantity based on the real-time three-phase current and voltage data during the operation of the static var generator includes: real-time acquisition of real-time three-phase current and voltage data of each component inside the static var generator, and addition of the real-time three-phase current and voltage data acquired at the same sampling time to obtain the instantaneous value of the zero-sequence current. The effective value of the zero-sequence current is obtained by performing an arithmetic average filter on the instantaneous value of the zero-sequence current within a single continuous power frequency cycle. The absolute value of the difference between the effective values ​​of the zero-sequence current between two adjacent power frequency cycles is calculated based on the real-time three-phase current and voltage data to obtain the ground current mutation rate. The system voltage phase information is obtained by real-time tracking of the phase change of the flexible AC transmission system voltage through a phase-locked loop synchronization system voltage phase. The phase difference angle between the fundamental component of the grounding current and the zero-sequence component of the flexible AC transmission system voltage is calculated based on the system voltage phase information to obtain the phase offset. The effective value of the zero-sequence current, the ground current mutation rate, and the phase offset are combined to form the zero-sequence ground current characteristic quantity.

3. The method for ground fault protection of a static var generator as described in claim 2, characterized in that, The step of determining the ground fault load distribution imbalance area of ​​the static var generator based on the zero-sequence ground current characteristic includes: comparing the effective value of the zero-sequence current with a preset ground fault threshold, and when the effective value of the zero-sequence current exceeds the preset ground fault threshold, mapping the physical location of the ground fault imbalance inside the static var generator based on the phase offset and the ground current mutation rate. Based on the physical location of the fault imbalance, the ground fault load distribution imbalance area is determined using the internal electrical topology of the static var generator.

4. The method for ground fault protection of a static var generator as described in claim 1, characterized in that, The steps of evaluating the electrical coupling stability of the fault area based on the electrical coupling correlation data between different components inside the static var generator, and obtaining the current electrical stability status and a list of key influencing components, include: Obtain the power transfer impedance between different components inside the static var generator located in the ground fault load distribution imbalance region; The magnetic coupling coefficient is obtained by comparing the voltage change to the current change caused by magnetic coupling between different components inside the static var generator. The power transmission impedance and the magnetic coupling coefficient are weighted and fused to obtain electrical coupling correlation data, and the change in electrical coupling correlation data between adjacent sampling periods is calculated. The degree of electrical coupling fluctuation is obtained by summing the squares of the deviations between the change in electrical coupling correlation data and the average change in electrical coupling correlation data. The electrical coupling fluctuation level is compared with a preset stability threshold to obtain an electrical stability comparison result, and the current electrical stability state is determined based on the electrical stability comparison result. When the current electrical stability state is electrical instability, the components in the ground fault load distribution imbalance area are screened according to the degree of electrical coupling fluctuation, and a list of key influencing components is constructed.

5. A method for protecting a static var generator from grounding faults as described in claim 1, characterized in that, The step of dynamically adjusting the load distribution in the ground fault load distribution imbalance area based on the current electrical stability status and the list of key influencing components to obtain an optimized load distribution scheme includes: When the current electrical stability state is electrical instability, the dominant factors of electrical instability are determined, and the coordination factor is calculated based on the dominant factors of electrical instability. Based on the list of key influencing components, obtain the key operating state vectors associated with each key influencing component within the ground fault load distribution imbalance area; Calculate the deviation between the target reactive power setpoint and the actual reactive power data for each key influencing component to obtain the error signal; Using the error signal and the coordination factor as inputs, the adjustment increment of the key operating state vector is calculated using the proportional-integral control method; The adjustment increment is superimposed on the key operating state vector to obtain the key operating state optimization vector; the reactive power output optimization amount of each key influencing component is determined by the key operating state optimization vector and real-time load allocation data, and the load allocation optimization scheme is determined based on the reactive power output optimization amount.

6. The method for ground fault protection of a static var generator as described in claim 5, characterized in that: The key operating state vector includes pulse width modulation duty cycle, carrier frequency, and output voltage phase.

7. A method for protecting a static var generator from ground faults as described in claim 5, characterized in that, The steps for determining the optimal protection action timing based on real-time voltage and current change rate data and typical ground fault waveforms include: Obtain the current operating status data of the power devices associated with each key influencing component, and calculate the real-time voltage change rate and real-time current change rate of the power devices associated with each key influencing component based on the current operating status data; The average values ​​of the real-time voltage change rate and the real-time current change rate for all power devices are calculated to obtain the corresponding voltage rise rate and current change rate. The similarity between the real-time waveform composed of the voltage rise rate and the current change rate and the typical ground fault waveform is calculated to obtain the waveform similarity. When the waveform similarity is not less than the preset waveform similarity threshold, the coordination factor is used to correct the time of successful protection actions of the same type in the past to obtain the optimal protection action timing. When the waveform similarity is less than the preset waveform similarity threshold, the standard protection delay is corrected using the waveform similarity to obtain the optimal protection action timing.

8. A method for protecting a static var generator from ground faults as described in claim 1, characterized in that, The step of generating a protection action instruction set based on the optimal protection action timing and the load allocation optimization scheme includes: The load allocation optimization scheme is analyzed to extract the load allocation status of each key influencing component. Based on the load allocation status, a preset protection action priority mapping table is matched to extract the protection action priority corresponding to the load allocation status. The coordination time interval parameter between adjacent protection actions is calculated based on the delay of the action time point associated with the load distribution state relative to the fault initiation time. Using the protection action priority as the benchmark weight, the comprehensive priority index of each protection action is calculated by utilizing the load ratio of each component inside the static var generator in real time in the load allocation optimization scheme. The protection actions in the load allocation optimization scheme are arranged in descending order according to the comprehensive priority index to form a protection action execution sequence, and the optimal protection action timing is taken as the action time of the first protection action in the protection action execution sequence. Starting from the second protection action in the protection action execution sequence, the action time of the previous protection action is superimposed with the coordination time interval parameter corresponding to the current protection action to obtain the action time of the current protection action. A set of protection action instructions is generated based on the protection action identifier and action time corresponding to each protection action in the protection action execution sequence.

9. A ground fault protection system for a static var generator, characterized in that, The system includes: The feature extraction module is used to extract the zero-sequence grounding current feature based on the real-time three-phase current and voltage data during the operation of the static var generator. The imbalance analysis module is used to determine the imbalance area of ​​the ground fault load distribution of the static var generator based on the zero-sequence ground current characteristics. The stability analysis module is used to evaluate the electrical coupling stability of the fault area in the ground fault load distribution imbalance area based on the electrical coupling correlation data between different components inside the static var generator, and obtain the current electrical stability status and a list of key influencing components. The load distribution module is used to dynamically adjust the load distribution in the ground fault load distribution imbalance area according to the current electrical stability status and the list of key influencing components, so as to obtain an optimized load distribution scheme. The action analysis module is used to determine the optimal timing for protection action based on real-time voltage and current change rate data and typical ground fault waveforms. The fault protection module is used to generate a set of protection action instructions based on the optimal protection action timing and the load distribution optimization scheme, and to use the set of protection action instructions to control the static var generator to perform ground fault protection.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method as described in any one of claims 1 to 8.

Images