Bus fault analysis method and system for voltage sag

Abstract

The invention discloses a bus fault analysis method and system for voltage sag, and relates to the technical field of bus fault analysis. The method comprises the following steps: synchronously acquiring three-phase voltage waveform data of a bus through a multi-source sensor, and obtaining a voltage sag event data set; performing sag feature extraction on the voltage sag event data set to generate a feature vector group; performing fault type identification according to the feature vector group in combination with a bus topological structure, and determining a fault judgment result; generating a dynamic reactive power compensation instruction based on the fault judgment result, performing adjustment through the dynamic reactive power compensation instruction to perform sag compensation on the bus voltage, and generating voltage compensation waveform data; and performing bus fault analysis according to the voltage compensation waveform data to generate a bus fault report. The technical problem that the bus fault analysis is not accurate enough in the prior art is solved, and the technical effect of improving the bus fault analysis accuracy is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of bus fault analysis, and particularly to a method and system for bus fault analysis for voltage sags. Background Art

[0002] With the continuous increase in the complexity and scale of power systems, bus faults and voltage sag problems have gradually become key factors affecting power stability and power supply quality. Voltage sags are usually caused by bus faults, equipment failures, or load fluctuations, etc., which may lead to equipment damage, production interruption, and a decline in user experience. Traditional methods for dealing with voltage sags mostly rely on empirical judgment and static compensation, and it is difficult to identify and respond to different types of faults in real time and accurately. Especially in complex power systems, there is often a large uncertainty in the identification of fault types and occurrence locations. Summary of the Invention

[0003] This application provides a method and system for bus fault analysis for voltage sags, which solves the technical problem of inaccurate bus fault analysis in the prior art.

[0004] In the first aspect of this application, a method for bus fault analysis for voltage sags is provided. The method includes:

[0005] Synchronously collecting three-phase voltage waveform data of the bus through multi-source sensors to obtain a voltage sag event data set; extracting sag features from the voltage sag event data set to generate a feature vector group; identifying the fault type according to the feature vector group in combination with the bus topology structure to determine the fault discrimination result; generating a dynamic reactive power compensation instruction based on the fault discrimination result, and adjusting through the dynamic reactive power compensation instruction to perform voltage sag compensation on the bus voltage to generate voltage compensation waveform data; performing bus fault analysis according to the voltage compensation waveform data to generate a bus fault report.

[0006] In the second aspect of this application, a system for bus fault analysis for voltage sags is provided. The system includes:

[0007] A data acquisition module for synchronously collecting three-phase voltage waveform data of the bus through multi-source sensors to obtain a voltage sag event data set; a feature extraction module for extracting sag features from the voltage sag event data set to generate a feature vector group; a fault identification module for identifying the fault type according to the feature vector group in combination with the bus topology structure to determine the fault discrimination result; a compensation module for generating a dynamic reactive power compensation instruction based on the fault discrimination result, and adjusting through the dynamic reactive power compensation instruction to perform voltage sag compensation on the bus voltage to generate voltage compensation waveform data; a fault analysis module for performing bus fault analysis according to the voltage compensation waveform data to generate a bus fault report.

[0008] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0009] First, synchronously collect the three-phase voltage waveform data of the bus through multi-source sensors to obtain a voltage sag event data set. Then, extract the sag characteristics from the voltage sag event data set to generate a feature vector group. Further, identify the fault type according to the feature vector group in combination with the bus topology structure to determine the fault discrimination result. Then, generate a dynamic reactive power compensation instruction based on the fault discrimination result, and adjust the bus voltage through the dynamic reactive power compensation instruction to perform voltage sag compensation to generate voltage compensation waveform data. Finally, perform bus fault analysis based on the voltage compensation waveform data to generate a bus fault report. This solves the technical problem of inaccurate bus fault analysis in the prior art and achieves the technical effect of improving the accuracy of bus fault analysis. Brief Description of the Drawings

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0011] Figure 1 It is a schematic flowchart of the bus fault analysis method for voltage sag provided by the embodiment of this application;

[0012] Figure 2 It is a schematic structural diagram of the bus fault analysis system for voltage sag provided by the embodiment of this application.

[0013] Description of the reference numerals: Data acquisition module 11, feature extraction module 12, fault identification module 13, compensation module 14, fault analysis module 15. Detailed Description of the Embodiments

[0014] This application provides a bus fault analysis method and system for voltage sag, which solves the technical problem of inaccurate bus fault analysis in the prior art.

[0015] The following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0016] It should be noted that the terms "include" and "have" are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or modules that are not clearly listed or are inherent to these processes, methods, products, or devices.

[0017] Embodiment 1, as Figure 1 shown, this application provides a method for analyzing bus faults for voltage sags, where the method includes:

[0018] Synchronously collect three-phase bus voltage waveform data through multi-source sensors to obtain a voltage sag event dataset.

[0019] Real-time collect bus voltage data through multi-source sensors deployed at the bus. When the bus voltage amplitude is lower than a preset threshold, collect three-phase bus voltage waveform data, thereby generating a voltage sag event dataset.

[0020] Furthermore, synchronously collect three-phase bus voltage waveform data through multi-source sensors to obtain a voltage sag event dataset. The method includes:

[0021] Retrieve the historical operation characteristics of the bus for monitoring and analysis to obtain bus monitoring requirement information; construct a bus topology structure, and determine multiple regions to be monitored according to the bus monitoring requirement information in combination with the bus topology structure. The multiple regions to be monitored include multiple monitoring nodes; based on the multiple monitoring nodes, perform sensing deployment, sense the bus voltage through multi-source sensors to obtain the bus voltage amplitude; when the bus voltage amplitude is lower than a preset threshold, trigger the synchronous acquisition instruction of the multi-source sensors, and collect and obtain three-phase bus voltage waveform data through the synchronous acquisition instruction; perform time alignment processing on the three-phase bus voltage waveform data to generate the voltage sag event dataset.

[0022] First, by retrieving the historical operation data of the busbar, monitor and analyze the electrical characteristics of the busbar to obtain the busbar monitoring requirement information. The busbar monitoring requirement information is based on the comprehensive analysis of historical data such as busbar voltage fluctuations, load changes, and equipment operating states, and identifies the key areas and potential fault modes where voltage sag events may occur. Next, construct the busbar topology structure, combine the busbar monitoring requirement information to determine multiple areas to be monitored, and arrange multiple monitoring nodes in each area for real-time acquisition of voltage data. Then, arrange multi-source sensors (including voltage transformers, zero-sequence voltage sensors, and high-frequency recorders) on the determined monitoring areas and nodes to monitor electrical parameters such as the voltage amplitude and frequency of the busbar in real time; by continuously monitoring the busbar voltage, when the voltage amplitude is lower than the preset threshold, automatically trigger the multi-source sensor synchronous acquisition instruction, so that all monitoring nodes collect the three-phase voltage waveform data of the busbar at the same time. Finally, perform time alignment processing on the three-phase voltage waveform data of the busbar based on the GPS clock synchronization signal to ensure that the voltage data of different phases are accurately aligned in time, thereby generating a voltage sag event data set.

[0023] Furthermore, the process of constructing the busbar topology structure includes the following methods:

[0024] Record the real-time signals of multiple operating stages of the busbar to generate a switch state matrix; collect the load power data and distribution positions of the busbar to construct a load distribution density map; establish a busbar node admittance matrix according to the switch state matrix combined with the load distribution density map, and connect the busbar node admittance matrix according to the busbar grounding method parameters to construct the busbar topology structure.

[0025] Specifically, by real-time monitoring the switch states of each node of the busbar, record the switch operation conditions of the busbar at different time points, and convert these signal data into a switch state matrix to reflect the switch switching relationship between each node of the busbar; then, collect the load power data and its distribution positions of the busbar, and construct a load distribution density map based on these data. Among them, the load power data includes the power demand and position distribution of each load, and the load distribution density map reflects the load distribution of each area of the busbar; then, combine the switch state matrix and the load distribution density map to establish a busbar node admittance matrix. The busbar node admittance matrix is used to describe the mutual influence between electrical nodes and can reflect the mutual relationship of voltage, current, and power between each node; finally, use the busbar grounding method parameters (including neutral grounding resistance value, arc suppression coil compensation degree) to connect the busbar node admittance matrix to construct a complete busbar topology structure.

[0026] Extract the sag characteristics from the voltage sag event data set to generate a feature vector group.

[0027] Based on the wavelet transform algorithm, the voltage sag event dataset is used for sag feature extraction to generate a feature vector group including the sag amplitude, phase mutation, and duration. Herein, the duration refers to the time period from the start to the recovery of the voltage sag.

[0028] Furthermore, for the voltage sag event dataset, sag feature extraction is performed to generate a feature vector group. The method includes:

[0029] Based on the voltage sag event dataset, multi-level decomposition extraction is performed to obtain the multi-band energy distribution characteristics; the sag start points of the three-phase voltages are determined according to the voltage sag event dataset, and phase analysis is performed in combination with the multi-band energy distribution characteristics according to the sag start points to determine the phase mutation angle data of the sag start points; sag marking is performed according to the phase mutation angle data to determine the sag duration label; the displacement voltage and zero-sequence current of the neutral point are determined according to the multi-band energy distribution characteristics, and the transition resistance range of the ground fault is identified through the ratio analysis of the displacement voltage and the zero-sequence current of the neutral point; the multi-band energy distribution characteristics, the phase mutation angle data, the sag duration label, and the transition resistance range are associated and integrated to determine the feature vector group.

[0030] First, based on the voltage sag event dataset, wavelet transform is used to perform multi-scale decomposition on the voltage waveform signal; wavelet transform can effectively decompose the bus three-phase voltage waveform data into multiple frequency levels. By analyzing the energy distribution characteristics of different frequency bands, the time-frequency characteristics of voltage sag events in different frequency ranges are extracted. Then, according to the voltage sag event dataset, the sag start points of the three-phase voltages are determined. The sag start points of the three-phase voltages are the start moments when the voltage waveform drops from the normal state to the sag state; by analyzing the time-domain characteristics of the voltage waveform signal and combining the results after wavelet transform, the start moment of the voltage sag can be accurately calibrated. Combining the sag start points, phase analysis is performed, and in combination with the multi-band energy distribution characteristics, the phase mutation angle at the sag start point is determined. The phase mutation angle can reflect the sharp change of the voltage waveform to facilitate the identification of the sag type.

[0031] Based on the phase mutation angle data, voltage sag marking is performed, and the voltage sag duration label is further determined according to this marking. The voltage sag duration is the time length from the starting point of the voltage sag to the restoration of the normal voltage. By calibrating the phase mutation of the voltage waveform, the duration of the voltage sag can be accurately calculated, providing a key time parameter for subsequent voltage restoration and compensation decisions. In addition, based on the multi-band energy distribution characteristics, the displacement voltage of the neutral point and the zero-sequence current are further determined; the displacement voltage of the neutral point is the voltage change caused by the ground fault, and the zero-sequence current is the current generated by the ground fault; by calculating the ratio of the displacement voltage of the neutral point to the zero-sequence current, the range of the transition resistance of the ground fault can be identified, thereby providing strong support for the analysis of the fault type and fault location. Finally, the multi-band energy distribution characteristics, phase mutation angle data, voltage sag duration label, and transition resistance range extracted above are associated and integrated to generate a complete feature vector group. This feature vector group comprehensively reflects the key characteristics of the voltage sag event, including the voltage sag amplitude, phase change, duration, and ground fault characteristics, and can provide accurate data support for subsequent fault diagnosis, voltage sag compensation, dynamic reactive power compensation, and power system stability analysis.

[0032] Based on the feature vector group and combined with the bus topology structure, fault type identification is carried out to determine the fault discrimination result.

[0033] Based on the feature vector group and combined with the bus topology structure, fault type identification is carried out. First, the extracted feature vector group is used as input data and preliminarily judged through a fault type expert system. The fault type expert system performs pattern matching according to the preset rule base and the information in the feature vector (such as voltage sag amplitude, phase mutation, duration, etc.) to preliminarily identify possible fault types. Subsequently, combined with the connection mode, grounding mode, and load distribution of each node in the bus topology structure, the determination of the fault type is further optimized. Finally, according to the analysis result, the fault type and its confidence level are determined, thereby obtaining the fault discrimination result, providing decision support for power system fault handling and compensation.

[0034] Furthermore, based on the feature vector group and combined with the bus topology structure, fault type identification is carried out to determine the fault discrimination result. The method includes:

[0035] Input the feature vector group into a preset fault type expert system, perform fault type matching through the call rule base of the fault type expert system, and generate a fault discrimination result, where the fault discrimination result includes a discrimination confidence level; make a determination in combination with the bus topology structure according to the discrimination confidence level. When it is detected that the displacement voltage of the neutral point exceeds a preset threshold and the phase of the zero-sequence current lags behind the voltage by a preset fixed value, it is determined as single-phase grounding fault information; when the three-phase voltages drop symmetrically and the characteristics of the zero-sequence current are missing, it is determined as TV disconnection fault information; match the single-phase grounding fault information with the TV disconnection fault information to determine the fault discrimination result.

[0036] First, input the feature vector group into a preset fault type expert system. The fault type expert system performs fault type matching based on a preset call rule base and generates a fault discrimination result. This discrimination result includes the fault type and its corresponding discrimination confidence level, reflecting the reliability and accuracy of the fault diagnosis. Next, further determination is made in combination with the discrimination confidence level in the fault discrimination result and the bus topology structure. Specifically, when the system detects that the displacement voltage of the neutral point of the bus exceeds a preset threshold and the phase of the zero-sequence current lags behind the voltage by a preset fixed value (90°), the system determines it as a single-phase grounding fault. Additionally, when the system detects that the three-phase voltages drop symmetrically and the characteristics of the zero-sequence current are missing, the system determines it as a TV (voltage sag) disconnection fault. Finally, the system matches the single-phase grounding fault information with the TV disconnection fault information and combines the determination result of the fault type expert system to finally determine the fault discrimination result.

[0037] The call rule base of the fault type expert system includes the following key rules:

[0038] Rule 1: If the displacement voltage V0 of the neutral point in the feature vector group is greater than 0.15Un (Un is the rated voltage) and the phase of the zero-sequence current I0 lags behind V0 by 85° - 95°, then the single-phase grounding fault determination condition is triggered.

[0039] Rule 2: If the three-phase voltage symmetrically drops by an amplitude of ΔU a = ΔU b = ΔU c and V0 / I0 < 0.1Ω, then the TV disconnection fault determination condition is triggered.

[0040] Rule 3: When the transition resistance range R f ∈ [10Ω, 1000Ω], it is associated with the high-resistance grounding fault subtype of the distribution network.

[0041] Through these rules, the fault type expert system performs precise fault type matching on the voltage sag event according to the input feature vector group and generates the corresponding fault discrimination result.

[0042] Generate a dynamic reactive power compensation instruction based on the fault discrimination result, and adjust through the dynamic reactive power compensation instruction to perform voltage sag compensation on the bus voltage, generating voltage compensation waveform data.

[0043] Based on the fault discrimination result, the system generates a dynamic reactive power compensation instruction. For different types of faults (such as single-phase grounding fault or TV disconnection fault), the required reactive power compensation amount is determined by calculating fault characteristics (such as voltage sag amplitude, duration, and transition resistance range, etc.). Subsequently, the system performs voltage sag compensation on the bus voltage by adjusting equipment such as shunt capacitor banks and transformer tap changers, thereby quickly restoring the bus voltage to the normal level. During this process, compensation waveform data is generated and reflects the voltage change after compensation, providing a basis for the stability assessment of the power system and equipment fault diagnosis.

[0044] Furthermore, generating a dynamic reactive power compensation instruction based on the fault discrimination result, the method includes:

[0045] Extract multiple fault parameters of the bus according to the fault discrimination result, the multiple fault parameters include voltage sag depth parameter, fault phase parameter, impedance parameter; calculate based on the voltage sag depth parameter and the impedance parameter according to the fault phase parameter to obtain the dynamic reactive power compensation demand; perform bus compensation analysis according to the dynamic reactive power compensation demand, generating shunt capacitor bank switching instruction, main transformer voltage regulating tap adjustment instruction; add the shunt capacitor bank switching instruction and the main transformer voltage regulating tap adjustment instruction to the dynamic reactive power compensation instruction.

[0046] First, according to the fault discrimination results output by the fault type expert system, multiple fault parameters related to the bus are extracted. The fault parameters include, but are not limited to, the sag depth parameter, the fault phase parameter, and the impedance parameter. Among them, the sag depth parameter is used to describe the drop amplitude of the bus voltage relative to the rated voltage. The fault phase parameter is used to indicate the phase combination affected by the voltage sag (such as phase A, phase AB, three phases, etc.). The impedance parameter reflects the electrical impedance situation between the fault point and the bus and is a key indicator for evaluating the compensation ability. Based on the sag depth parameter and the impedance parameter, the system calculates according to the fault phase parameter, and then obtains the dynamic reactive power compensation demand. By combining the reactive power balance model of the power system, the system performs mathematical calculations, synthesizes the sag depth, impedance, and phase characteristics, and obtains the required dynamic reactive power compensation demand. The dynamic reactive power compensation demand is expressed as the reactive power value required to restore the bus to the rated voltage. Subsequently, based on the dynamic reactive power compensation demand, the system performs bus compensation analysis to generate specific execution instructions, mainly including the switching instructions of the shunt capacitor bank and the adjustment instructions of the tap changer of the main transformer. Among them, the switching of the shunt capacitor bank is used to quickly provide the required reactive power to improve the voltage level; the adjustment of the tap changer of the main transformer realizes the fine adjustment of the system voltage by changing the transformer ratio. Finally, the system combines and integrates the switching instructions of the shunt capacitor bank and the adjustment instructions of the tap changer of the main transformer to form a complete dynamic reactive power compensation instruction, which will be sent to the on-site control device to realize the automatic control of the compensation equipment and complete the dynamic regulation and rapid recovery of the bus voltage.

[0047] Furthermore, according to the dynamic reactive power compensation demand, bus compensation analysis is performed to generate the switching instructions of the shunt capacitor bank and the adjustment instructions of the tap changer of the main transformer. The method includes:

[0048] When the fault discrimination result is the single-phase grounding fault information, calculate the ratio of the sag depth parameter and the impedance parameter according to the fault phase parameter to dynamically adjust the switching capacity of the shunt capacitor bank, and generate the adjustment instruction of the tap changer of the main transformer; when the fault discrimination result is the TV disconnection fault information, start the data channel of the standby voltage transformer and block the automatic reclosing function of the associated relay protection device, and generate the switching instruction of the shunt capacitor bank.

[0049] When the fault discrimination result is the single-phase grounding fault information, the system dynamically adjusts the switching capacity of the shunt capacitor bank according to the fault phase parameter, combined with the ratio of the sag depth parameter and the impedance parameter. Through this calculation, the system can accurately adjust the capacity of the capacitor bank to provide appropriate reactive power compensation and restore the voltage to the normal level. At the same time, an adjustment instruction for the tap changer of the main transformer is generated to adjust the tap of the transformer and further optimize the bus voltage.

[0050] When the fault discrimination result is the TV disconnection fault information, the system will start the data channel of the standby voltage transformer, obtain more stable voltage data through the standby channel, and at the same time block the automatic reclosing function of the associated relay protection device to avoid system instability caused by the automatic reclosing operation. According to these control logics, the system generates switching instructions for the shunt capacitor bank, and quickly restores the bus voltage through precise reactive power compensation to ensure the stable operation of the power system.

[0051] Perform bus fault analysis based on the voltage compensation waveform data to generate a bus fault report.

[0052] Through the dynamic monitoring and data analysis of the voltage compensation waveform, the system can identify the timing of voltage recovery, the compensation effect, and the voltage change in the fault area, and further locate the area where the fault occurs. On this basis, the system generates a detailed bus fault report according to the voltage change and fault location information. The bus fault report includes fault location information, voltage sag suppression effect, and protection device blocking strategy.

[0053] Furthermore, performing bus fault analysis based on the voltage compensation waveform data to generate a bus fault report, the method includes:

[0054] Perform dynamic acquisition based on the voltage compensation waveform data to obtain the action timing data of the relay protection device; perform voltage compensation calculation according to the voltage compensation waveform data to obtain voltage compensation parameters, where the voltage compensation parameters include voltage recovery rate and harmonic distortion rate; formulate an evaluation index for the voltage sag suppression effect of the bus according to the voltage recovery rate and the harmonic distortion rate; traverse the voltage compensation waveform data for voltage change analysis, delimit the fault interval by the voltage gradient change, and perform positioning according to the fault interval delimited by the voltage gradient change in combination with the bus topology structure to obtain fault location information; perform optimization analysis according to the voltage sag suppression effect evaluation index in combination with the action timing data of the relay protection device to generate an optimized instruction for the protection blocking strategy; execute the optimized instruction for the protection blocking strategy based on the fault location information according to the voltage sag suppression effect evaluation index to generate the bus fault report.

[0055] First, perform dynamic acquisition based on the voltage compensation waveform data to obtain the action timing data of the relay protection device. The action timing data of the relay protection device records the response time series of the relay protection device during the fault occurrence. Specifically, by recording the response process of the relay protection device during the fault occurrence, the synchronous analysis between the action of the protection device and the voltage change is ensured, providing real-time protection response data for subsequent fault handling.

[0056] Secondly, voltage compensation calculations are performed based on the voltage compensation waveform data to obtain voltage compensation parameters, where the voltage compensation parameters include the voltage recovery rate and the harmonic distortion rate. The voltage recovery rate is used to measure the speed at which the voltage recovers from a sag to the normal level, while the harmonic distortion rate reflects the possible harmonic effects during the voltage recovery process. Through this calculation, the system can evaluate the effectiveness of voltage compensation and the power quality of the power system. Based on the voltage recovery rate and the harmonic distortion rate, the system formulates an evaluation index for the sag suppression effect of the busbar. This evaluation index is used to measure the balance between the voltage recovery efficiency and the power quality during the voltage compensation process, providing a comprehensive evaluation of the suppression effect of power system sag events. Next, the voltage compensation waveform data is traversed for voltage change analysis to delimit the fault interval based on the voltage gradient change and locate the fault in combination with the busbar topology structure. By analyzing the voltage waveform changes, the specific area of voltage change is determined, and then combined with the busbar topology structure, the specific location where the fault occurs is accurately located. On this basis, according to the sag suppression effect evaluation index, an optimization analysis is performed in combination with the action timing data of the relay protection device, and an optimized instruction for the protection blocking strategy is generated. This instruction is used to optimize the action strategy of the relay protection device to ensure that the protection device can respond quickly and perform appropriate protection operations when a fault occurs. Finally, based on the fault location information, the optimized instruction for the protection blocking strategy is executed according to the sag suppression effect evaluation index to generate a busbar fault report.

[0057] Furthermore, based on the fault location information, the optimized instruction for the protection blocking strategy is executed according to the sag suppression effect evaluation index to generate the busbar fault report. The method includes:

[0058] Traverse the historical fault case library for similarity analysis according to the sag suppression effect evaluation index to construct a multi-dimensional correlation matrix; analyze the multi-dimensional correlation matrix for random prediction to generate a multi-dimensional prediction result; execute the optimized instruction for the protection blocking strategy to fuse the multi-dimensional prediction result with the fault location information to generate the busbar fault report.

[0059] Specifically, through in-depth analysis of historical fault cases, the relevance between historical fault events and their corresponding voltage recovery conditions, compensation strategies, protection responses, etc. is extracted to generate a multi-dimensional correlation matrix. The matrix contains data relationships in multiple dimensions such as fault types, sag depths, compensation effects, protection strategies, etc. Then, the multi-dimensional correlation matrix is analyzed, and random prediction is performed to generate multi-dimensional prediction results. By using the random forest algorithm to analyze the data in the correlation matrix, the system can predict the possible voltage recovery conditions, compensation requirements, and protection device responses when similar faults occur. Then, the system executes the protection blocking strategy optimization instruction and fuses the multi-dimensional prediction results with the fault location information; by combining the predicted fault mode with the real-time fault location data, the optimized protection blocking strategy can more accurately guide the responses of protection devices and compensation equipment in the power system, ensuring that the protection device can take compensation measures in a timely and effective manner when a fault occurs and avoiding the spread of the fault. Finally, based on the fused information, the system generates a detailed bus fault report, which includes the fault type, fault location, compensation measures, results of protection strategy optimization, relevant analysis of historical fault cases, and prediction results, comprehensively demonstrating the whole process of fault handling.

[0060] In summary, the embodiments of the present application at least have the following technical effects:

[0061] First, the three-phase voltage waveform data of the bus is synchronously collected by multi-source sensors to obtain a voltage sag event data set. Then, the sag characteristics are extracted from the voltage sag event data set to generate a feature vector group. Further, based on the feature vector group and the bus topology structure, the fault type is identified to determine the fault discrimination result. Then, a dynamic reactive power compensation instruction is generated based on the fault discrimination result, and the bus voltage is compensated for sag through the dynamic reactive power compensation instruction to generate voltage compensation waveform data. Finally, the bus fault is analyzed based on the voltage compensation waveform data to generate a bus fault report. This solves the technical problem of inaccurate bus fault analysis in the prior art and achieves the technical effect of improving the accuracy of bus fault analysis.

[0062] Embodiment 2, based on the same inventive concept as the bus fault analysis method for voltage sag in the foregoing embodiment, as Figure 2 shown, the present application provides a bus fault analysis system for voltage sag, wherein the system includes:

[0063] The data acquisition module 11 is used to synchronously collect the three-phase voltage waveform data of the bus through multi-source sensors to obtain a voltage sag event data set; the feature extraction module 12 is used to extract the sag features from the voltage sag event data set to generate a feature vector group; the fault identification module 13 is used to identify the fault type according to the feature vector group in combination with the bus topology structure to determine the fault discrimination result; the compensation module 14 is used to generate a dynamic reactive power compensation instruction based on the fault discrimination result, and adjust the bus voltage through the dynamic reactive power compensation instruction to perform voltage sag compensation to generate voltage compensation waveform data; the fault analysis module 15 is used to perform bus fault analysis according to the voltage compensation waveform data to generate a bus fault report.

[0064] Further, the data acquisition module 11 is used to execute the following method:

[0065] Retrieve the historical operation characteristics of the bus for monitoring and analysis to obtain bus monitoring requirement information; construct the bus topology structure, and determine multiple monitoring areas according to the bus monitoring requirement information in combination with the bus topology structure. The multiple monitoring areas include multiple monitoring nodes; based on the multiple monitoring nodes, perform sensing deployment, sense the bus voltage through multi-source sensors to obtain the bus voltage amplitude; when the bus voltage amplitude is lower than a preset threshold, trigger the synchronous acquisition instruction of the multi-source sensors, and collect and obtain the three-phase voltage waveform data of the bus through the synchronous acquisition instruction; perform time alignment processing on the three-phase voltage waveform data of the bus to generate the voltage sag event data set.

[0066] Further, the data acquisition module 11 is used to execute the following method:

[0067] Record the real-time signals of multiple operation stages of the bus to generate a switch state matrix; collect the load power data and distribution positions of the bus to construct a load distribution density map; establish a bus node admittance matrix according to the switch state matrix in combination with the load distribution density map, and connect the bus node admittance matrix according to the bus grounding mode parameters to construct the bus topology structure.

[0068] Further, the feature extraction module 12 is used to execute the following method:

[0069] Perform multi-layer decomposition extraction based on the voltage sag event dataset to obtain multi-band energy distribution characteristics; determine the sag start point of the three-phase voltage according to the voltage sag event dataset, and perform phase analysis in combination with the multi-band energy distribution characteristics according to the sag start point to determine the phase mutation angle data of the sag start point; perform sag marking according to the phase mutation angle data to determine the sag duration label; determine the displacement voltage and zero-sequence current of the neutral point according to the multi-band energy distribution characteristics, and identify the transition resistance range of the ground fault through the ratio analysis of the displacement voltage and the zero-sequence current of the neutral point; associate and integrate the multi-band energy distribution characteristics, the phase mutation angle data, the sag duration label, and the transition resistance range to determine the feature vector group.

[0070] Further, the fault identification module 13 is used to execute the following method:

[0071] Input the feature vector group into a preset fault type expert system, perform fault type matching through the call rule library of the fault type expert system, generate a fault discrimination result, and the fault discrimination result includes a discrimination confidence level; make a determination in combination with the bus topology structure according to the discrimination confidence level. When it is detected that the displacement voltage of the neutral point exceeds a preset threshold and the phase of the zero-sequence current lags behind the voltage by a preset fixed value, it is determined as single-phase ground fault information; when the three-phase voltage drops symmetrically and the characteristics of the zero-sequence current are missing, it is determined as TV disconnection fault information; match the single-phase ground fault information and the TV disconnection fault information to determine the fault discrimination result.

[0072] Further, the compensation module 14 is used to execute the following method:

[0073] Extract multiple fault parameters of the bus according to the fault discrimination result, and the multiple fault parameters include a sag depth parameter, a fault phase parameter, and an impedance parameter; calculate based on the sag depth parameter and the impedance parameter according to the fault phase parameter to obtain the dynamic reactive power compensation demand; perform bus compensation analysis according to the dynamic reactive power compensation demand to generate switching instructions for shunt capacitor banks and regulation instructions for the tap changers of main transformers; add the switching instructions for shunt capacitor banks and the regulation instructions for the tap changers of main transformers to the dynamic reactive power compensation instructions.

[0074] Further, the compensation module 14 is used to execute the following method:

[0075] When the fault discrimination result is the single-phase grounding fault information, calculate the sag depth parameter and the ratio of the impedance parameters according to the fault phase parameter, dynamically adjust the switching capacity of the shunt capacitor bank, and generate the regulating command for the main transformer tap changer; when the fault discrimination result is the TV disconnection fault information, start the data channel of the standby voltage transformer and block the automatic reclosing function of the associated relay protection device, and generate the switching command for the shunt capacitor bank.

[0076] Further, the fault analysis module 15 is used to execute the following method:

[0077] Based on the dynamic acquisition of the voltage compensation waveform data, obtain the action timing data of the relay protection device; perform voltage compensation calculation according to the voltage compensation waveform data to obtain voltage compensation parameters, where the voltage compensation parameters include voltage recovery rate and harmonic distortion rate; formulate the evaluation index for the sag suppression effect of the bus according to the voltage recovery rate and the harmonic distortion rate; traverse the voltage compensation waveform data for voltage change analysis, delimit the fault interval by the voltage gradient change, and perform positioning according to the fault interval located by the voltage gradient change in combination with the bus topology structure to obtain the fault location information; perform optimization analysis according to the sag suppression effect evaluation index in combination with the action timing data of the relay protection device to generate the optimized instruction for the protection blocking strategy; based on the fault location information, execute the optimized instruction for the protection blocking strategy according to the sag suppression effect evaluation index to generate the bus fault report.

[0078] Further, the fault analysis module 15 is used to execute the following method:

[0079] Traverse the historical fault case library for similarity analysis according to the sag suppression effect evaluation index, construct a multi-dimensional correlation matrix; analyze the multi-dimensional correlation matrix for random prediction to generate a multi-dimensional prediction result; execute the optimized instruction for the protection blocking strategy to fuse the multi-dimensional prediction result with the fault location information to generate the bus fault report.

[0080] It should be noted that the above sequence of the embodiments of the present application is only for description and does not represent the advantages or disadvantages of the embodiments. And the above description of specific embodiments of this specification has been made. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multi-tasking and parallel processing are also possible or may be advantageous.

[0081] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0082] This specification and the drawings are merely illustrative of the present application and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application. Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the present application and its equivalent technologies, the present application is intended to include these changes and modifications therein.

Claims

1. A method for analyzing bus faults for voltage sags, characterized in that, The method includes: Synchronously collecting bus three-phase voltage waveform data through multi-source sensors to obtain a voltage sag event data set; Performing sag feature extraction on the voltage sag event data set to generate a feature vector group; Identifying the fault type based on the feature vector group in combination with the bus topology structure to determine the fault discrimination result; Generating a dynamic reactive power compensation instruction based on the fault discrimination result, and adjusting through the dynamic reactive power compensation instruction to perform voltage sag compensation on the bus voltage to generate voltage compensation waveform data; Performing bus fault analysis based on the voltage compensation waveform data to generate a bus fault report.

2. The method for analyzing bus faults for voltage sags according to claim 1, characterized in that, Synchronously collecting bus three-phase voltage waveform data through multi-source sensors to obtain a voltage sag event data set, the method includes: Retrieving the historical operation characteristics of the bus for monitoring and analysis to obtain bus monitoring requirement information; Constructing a bus topology structure, and determining multiple monitoring areas according to the bus monitoring requirement information in combination with the bus topology structure, the multiple monitoring areas include multiple monitoring nodes; Performing sensing deployment based on the multiple monitoring nodes, and performing voltage sensing on the bus through multi-source sensors to obtain the bus voltage amplitude; When the bus voltage amplitude is lower than a preset threshold, triggering the synchronous acquisition instruction of the multi-source sensors, and collecting and obtaining bus three-phase voltage waveform data through the synchronous acquisition instruction; Performing time alignment processing on the bus three-phase voltage waveform data to generate the voltage sag event data set.

3. The bus fault analysis method for voltage sags according to claim 2, characterized in that The process of constructing a bus topology structure, the method includes: Performing real-time signal recording on multiple operation stages of the bus to generate a switch state matrix; Collecting the load power data and distribution positions of the bus to construct a load distribution density map; Establishing a bus node admittance matrix according to the switch state matrix in combination with the load distribution density map, and connecting the bus node admittance matrix according to the bus grounding mode parameters to construct the bus topology structure.

4. The bus fault analysis method for voltage sags according to claim 1, characterized in that, Performing sag feature extraction on the voltage sag event data set to generate a feature vector group, the method includes: Performing multi-layer decomposition extraction based on the voltage sag event data set to obtain multi-band energy distribution characteristics; Determining the sag starting point of the three-phase voltage according to the voltage sag event data set, and performing phase analysis according to the sag starting point in combination with the multi-band energy distribution characteristics to determine the phase mutation angle data of the sag starting point; Performing sag marking according to the phase mutation angle data to determine the sag duration label; Determining the neutral point displacement voltage and zero-sequence current according to the multi-band energy distribution characteristics, and identifying the transition resistance range of the ground fault through the ratio analysis of the neutral point displacement voltage and the zero-sequence current; Associating and integrating the multi-band energy distribution characteristics, the phase mutation angle data, the sag duration label, and the transition resistance range to determine the feature vector group.

5. The bus fault analysis method for voltage sags according to claim 4, wherein Identifying the fault type based on the feature vector group in combination with the bus topology structure to determine the fault discrimination result, the method includes: Input the feature vector group into a preset fault type expert system, perform fault type matching through the call rule base of the fault type expert system, and generate a fault discrimination result, where the fault discrimination result includes a discrimination confidence level; Make a determination according to the discrimination confidence level in combination with the bus topology structure. When it is detected that the displacement voltage of the neutral point exceeds a preset threshold and the phase of the zero-sequence current lags the voltage by a preset fixed value, it is determined as single-phase grounding fault information; When the three-phase voltages drop symmetrically and the characteristics of the zero-sequence current are missing, it is determined as TV disconnection fault information; Match the single-phase grounding fault information with the TV disconnection fault information to determine the fault discrimination result.

6. The bus fault analysis method for voltage sags according to claim 5, characterized in that, Generate a dynamic reactive power compensation instruction based on the fault discrimination result. The method includes: Extract multiple fault parameters of the bus according to the fault discrimination result, where the multiple fault parameters include a sag depth parameter, a fault phase parameter, and an impedance parameter; Calculate based on the sag depth parameter and the impedance parameter according to the fault phase parameter to obtain the dynamic reactive power compensation demand; Conduct bus compensation analysis according to the dynamic reactive power compensation demand, and generate a switching instruction for the shunt capacitor bank and an adjustment instruction for the tap changer of the main transformer; Add the switching instruction for the shunt capacitor bank and the adjustment instruction for the tap changer of the main transformer to the dynamic reactive power compensation instruction.

7. The bus fault analysis method for voltage sags according to claim 6, wherein Conduct bus compensation analysis according to the dynamic reactive power compensation demand, and generate a switching instruction for the shunt capacitor bank and an adjustment instruction for the tap changer of the main transformer. The method includes: When the fault discrimination result is the single-phase grounding fault information, dynamically adjust the switching capacity of the shunt capacitor bank by calculating the ratio of the sag depth parameter and the impedance parameter according to the fault phase parameter, and generate the adjustment instruction for the tap changer of the main transformer; When the fault discrimination result is the TV disconnection fault information, start the data channel of the standby voltage transformer and block the automatic reclosing function of the associated relay protection device, and generate the switching instruction for the shunt capacitor bank.

8. The bus fault analysis method for voltage sags according to claim 1, wherein, Conduct bus fault analysis according to the voltage compensation waveform data, and generate a bus fault report. The method includes: Perform dynamic acquisition based on the voltage compensation waveform data to obtain the action timing data of the relay protection device; Conduct voltage compensation calculation according to the voltage compensation waveform data to obtain voltage compensation parameters, where the voltage compensation parameters include a voltage recovery rate and a harmonic distortion rate; Formulate an evaluation index for the sag suppression effect of the bus according to the voltage recovery rate and the harmonic distortion rate; Traverse the voltage compensation waveform data for voltage change analysis, delimit the fault interval by the voltage gradient change, and locate according to the fault interval delimited by the voltage gradient change in combination with the bus topology structure to obtain fault location information; Perform optimization analysis according to the sag suppression effect evaluation index in combination with the action timing data of the relay protection device to generate an optimization instruction for the protection blocking strategy; Execute the optimization instruction for the protection blocking strategy based on the fault location information according to the sag suppression effect evaluation index to generate the bus fault report.

9. The bus fault analysis method for voltage sags according to claim 8, characterized in that, Execute the protection blocking strategy optimization instruction according to the fault location information in accordance with the voltage sag suppression effect evaluation index, and generate the bus fault report. The method includes: Perform a traversal similarity analysis on the historical fault case library according to the voltage sag suppression effect evaluation index to construct a multi-dimensional correlation matrix; Analyze the multi-dimensional correlation matrix for random prediction to generate a multi-dimensional prediction result; Execute the protection blocking strategy optimization instruction to fuse the multi-dimensional prediction result with the fault location information to generate the bus fault report.

10. A bus fault analysis system for voltage sags, characterized in that, For implementing the bus fault analysis method for voltage sag according to any one of claims 1-9, the system includes: A data acquisition module for synchronously collecting bus three-phase voltage waveform data through multi-source sensors to obtain a voltage sag event data set; A feature extraction module for extracting voltage sag features from the voltage sag event data set to generate a feature vector group; A fault identification module for identifying the fault type according to the feature vector group in combination with the bus topology structure to determine the fault discrimination result; A compensation module for generating a dynamic reactive power compensation instruction based on the fault discrimination result, and adjusting the bus voltage through the dynamic reactive power compensation instruction to perform voltage sag compensation to generate voltage compensation waveform data; A fault analysis module for performing bus fault analysis according to the voltage compensation waveform data to generate a bus fault report.

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