A reactive power compensation device abnormality early warning method and system

Abstract

The application discloses a kind of reactive power compensation device abnormal early warning method and system, periodically update early warning threshold library, whether reactive power compensation device exists overvoltage risk based on early warning threshold library according to equivalent voltage factor and voltage skew, if yes, then output overvoltage early warning information, whether reactive power compensation device exists overcurrent risk based on early warning threshold library according to harmonic current square sum, if yes, then output overcurrent early warning information, whether reactive power compensation device exists capacitor deviation abnormal risk based on early warning threshold library according to capacitor deviation data, if yes, then output capacitor deviation abnormal early warning information, to more effectively and reliably early warning to overvoltage, overcurrent and capacitor deviation abnormality of reactive power compensation device, simultaneously periodically update early warning threshold library, ensure that threshold in early warning threshold library can be updated in real time according to recent history data, ensure the accurate early warning of abnormal risk, to realize more accurate and reliable abnormal early warning of reactive power compensation device.

Description

Technical Field

[0001] This invention relates to the field of reactive power compensation devices, and in particular to a method and system for early warning of abnormalities in reactive power compensation devices. Background Technology

[0002] Reactive power compensation and balance in a power system are fundamental conditions for ensuring voltage quality. Insufficient or excessive reactive power will cause a drop or rise in system voltage, and in extreme cases, can lead to a significant drop in voltage at certain key substation busbars, resulting in "voltage collapse." The large-scale integration of renewable energy sources such as photovoltaics and wind power has brought a series of technical challenges to the power grid. Power quality issues such as voltage fluctuations and increased harmonics are becoming more prominent, placing higher demands on the performance of reactive power compensation devices. On the one hand, reactive power compensation devices need to have higher stability and reliability to cope with various complex situations in the power system; on the other hand, they also need to have higher regulation capabilities and flexibility to adapt to the volatility and uncertainty of renewable energy generation. Therefore, utilizing digital technology to collect key operating data of reactive power compensation devices in real time, deeply analyze the trend characteristics of their operating status, and provide early warnings of anomalies is of great significance.

[0003] Typical fault types in reactive power compensation devices include bulging, blown fuses, component breakdown, switching failures, and oil leakage. Among these, overvoltage and overcurrent are the dominant external factors causing device failures. Bulging, blown fuses, and component breakdown are all reflected in changes in capacitance. Therefore, it is necessary to develop early warning systems for overvoltage, overcurrent, and capacitance deviation. Actual measurement data shows that abnormal operating conditions such as overvoltage, overcurrent, and capacitance deviation all have early signs of abnormality. By using online monitoring data obtained from reactive power compensation equipment status monitoring devices and employing data feature correlation analysis technology to determine abnormal operating states, early fault tracking and warning can be achieved, preventing fault development and escalation, and improving the operational reliability of the reactive power compensation device.

[0004] The main problem with issuing early warnings for overvoltage, overcurrent, and capacitance deviation in reactive power compensation devices is the difficulty in determining the warning thresholds and related criteria. Specifically, this manifests in the following aspects:

[0005] 1) Currently, the national standard defines the permissible operating level of long-term overvoltage amplitude, but it is difficult to reasonably determine the overvoltage warning threshold and criteria;

[0006] 2) Overcurrent is formed by the combined effect of harmonics and overvoltage of 1.1 times or less of the rated voltage. Considering the influence of harmonics, the warning threshold cannot be determined.

[0007] 3) The capacitor deviation warning threshold cannot be scientifically determined. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method and system for early warning of abnormalities in reactive power compensation devices, so as to achieve more accurate and reliable early warning of abnormalities in reactive power compensation devices.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A method for early warning of abnormalities in a reactive power compensation device includes the following steps:

[0011] Regularly update the early warning threshold database;

[0012] Obtain the equivalent voltage factor, voltage deviation, sum of squares of harmonic currents, and capacitor deviation data of the reactive power compensation device;

[0013] Based on the warning threshold library, the system determines whether the reactive power compensation device has an overvoltage risk according to the equivalent voltage factor and the voltage deviation. If so, it outputs an overvoltage warning message.

[0014] Based on the warning threshold library, the system determines whether the reactive power compensation device has an overcurrent risk according to the sum of squares of the harmonic currents. If so, an overcurrent warning message is output.

[0015] Based on the aforementioned warning threshold library, the system determines whether the reactive power compensation device has a risk of abnormal capacitance deviation according to the capacitance deviation data. If so, it outputs an abnormal capacitance deviation warning message.

[0016] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows:

[0017] A reactive power compensation device abnormality early warning system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it performs the following steps:

[0018] Regularly update the early warning threshold database;

[0019] Obtain the equivalent voltage factor, voltage deviation, sum of squares of harmonic currents, and capacitor deviation data of the reactive power compensation device;

[0020] Based on the warning threshold library, the system determines whether the reactive power compensation device has an overvoltage risk according to the equivalent voltage factor and the voltage deviation. If so, it outputs an overvoltage warning message.

[0021] Based on the warning threshold library, the system determines whether the reactive power compensation device has an overcurrent risk according to the sum of squares of the harmonic currents. If so, an overcurrent warning message is output.

[0022] Based on the aforementioned warning threshold library, the system determines whether the reactive power compensation device has a risk of abnormal capacitance deviation according to the capacitance deviation data. If so, it outputs an abnormal capacitance deviation warning message.

[0023] The beneficial effects of this invention are as follows: The warning threshold library is updated periodically. Based on the warning threshold library, the system determines whether the reactive power compensation device has an overvoltage risk based on the equivalent voltage factor and voltage skewness. If so, an overvoltage warning is output. Similarly, based on the warning threshold library, the system determines whether the reactive power compensation device has an overcurrent risk based on the sum of squared harmonic currents. If so, an overcurrent warning is output. Furthermore, based on the warning threshold library, the system determines whether the reactive power compensation device has a capacitor deviation anomaly risk based on capacitor deviation data. If so, a capacitor deviation anomaly warning is output. This allows for more effective and reliable warnings of overvoltage, overcurrent, and capacitor deviation anomalies in the reactive power compensation device. Furthermore, the periodic updating of the warning threshold library ensures that the thresholds in the library are updated in real time based on recent historical data, guaranteeing accurate warnings of anomalies and thus achieving more precise and reliable anomaly warnings for the reactive power compensation device. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the steps of an abnormal early warning method for a reactive power compensation device according to an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of an abnormal early warning system for a reactive power compensation device according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the early warning method for abnormality warning of reactive power compensation device according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram illustrating the generation of the capacitor deviation abnormal threshold in the reactive power compensation device abnormal early warning method according to an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of anomaly assessment in the reactive power compensation device anomaly early warning method according to an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the control diagram in the abnormal early warning method of the reactive power compensation device according to an embodiment of the present invention. Detailed Implementation

[0030] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0031] Please refer to Figure 1A method for early warning of abnormalities in a reactive power compensation device, comprising the following steps:

[0032] Regularly update the early warning threshold database;

[0033] Obtain the equivalent voltage factor, voltage deviation, sum of squares of harmonic currents, and capacitor deviation data of the reactive power compensation device;

[0034] Based on the warning threshold library, the system determines whether the reactive power compensation device has an overvoltage risk according to the equivalent voltage factor and the voltage deviation. If so, it outputs an overvoltage warning message.

[0035] Based on the warning threshold library, the system determines whether the reactive power compensation device has an overcurrent risk according to the sum of squares of the harmonic currents. If so, an overcurrent warning message is output.

[0036] Based on the aforementioned warning threshold library, the system determines whether the reactive power compensation device has a risk of abnormal capacitance deviation according to the capacitance deviation data. If so, it outputs an abnormal capacitance deviation warning message.

[0037] As can be seen from the above description, the beneficial effects of the present invention are as follows: The warning threshold library is updated periodically; based on the warning threshold library, the equivalent voltage factor and voltage skewness are used to determine whether the reactive power compensation device has an overvoltage risk; if so, an overvoltage warning is output. Based on the warning threshold library, the sum of squares of harmonic currents is used to determine whether the reactive power compensation device has an overcurrent risk; if so, an overcurrent warning is output. Based on the warning threshold library, the capacitor deviation data is used to determine whether the reactive power compensation device has a capacitor deviation anomaly risk; if so, a capacitor deviation anomaly warning is output. Thus, by using the equivalent voltage factor and voltage skewness to warn of overvoltage risk, by using the sum of squares of harmonic currents to warn of overcurrent risk, and by using capacitor deviation data to warn of capacitor deviation anomaly risk, the present invention can more effectively and reliably warn of overvoltage, overcurrent, and capacitor deviation anomalies in the reactive power compensation device. Simultaneously, the warning threshold library is updated periodically to ensure that the thresholds in the warning threshold library can be updated in real time based on recent historical data, ensuring accurate warning of abnormal risks, thereby achieving more accurate and reliable anomaly warnings for the reactive power compensation device.

[0038] Furthermore, the periodically updated early warning threshold database includes:

[0039] The equivalent voltage factor and voltage skewness of the reactive power compensation device are obtained for a historical preset time period, and the voltage step time and step order are identified based on the equivalent voltage factor.

[0040] Select the voltage deviation within a first preset time period before the voltage step moment and the voltage deviation within a first preset time period after the voltage step moment from the voltage deviation of the reactive power compensation device in the historical preset time period.

[0041] Calculate the average voltage deviation within a first preset time period before the voltage step moment, as the first overvoltage anomaly threshold corresponding to the step order, and calculate the voltage deviation within a first preset time period after the voltage step moment, as the second overvoltage anomaly threshold corresponding to the step order.

[0042] Update the first overvoltage anomaly threshold and the second overvoltage anomaly threshold to the early warning threshold library;

[0043] Select a target equivalent voltage factor that is less than or equal to a first preset value from the equivalent voltage factors of the reactive power compensation device during the preset historical time period, and obtain the fundamental current amplitude corresponding to the target equivalent voltage factor.

[0044] The overcurrent anomaly threshold is calculated based on the fundamental current amplitude, and the overcurrent anomaly threshold is updated to the warning threshold library;

[0045] Obtain the capacitor deviation data of the reactive power compensation device during the historical preset time period;

[0046] Based on the capacitance deviation data, the upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart are calculated using the control chart method. The upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart are then used as capacitance deviation abnormality thresholds to update the early warning threshold library.

[0047] At each preset time interval, the process returns to the step of obtaining the equivalent voltage factor and voltage deviation of the reactive power compensation device for the historical preset time period.

[0048] As described above, the equivalent voltage factor and voltage deviation of the reactive power compensation device over a historical preset time period are obtained. Based on these values, the overvoltage anomaly threshold is calculated and updated to the early warning threshold library. The overcurrent anomaly threshold is calculated based on the fundamental current amplitude corresponding to the target equivalent voltage factor and updated to the early warning threshold library. Based on the capacitance deviation data of the reactive power compensation device over a historical preset time period, the upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart are calculated using the control chart method and used as the capacitance deviation anomaly thresholds to update the early warning threshold library. This process determines more scientific and reasonable early warning thresholds for overvoltage, overcurrent, and capacitance deviation anomalies.

[0049] Furthermore, the calculation of the upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart based on the capacitance deviation data using the control chart method includes:

[0050] The capacitance deviation data is grouped to obtain multiple sample groups;

[0051] Calculate the mean and standard deviation of each sample group in the plurality of sample groups, and calculate the mean and standard deviation of the plurality of sample groups based on the mean and standard deviation of each sample group;

[0052] Calculate the upper control line, center line, and lower control line of the standard deviation control chart based on the standard deviation of the multiple sample groups;

[0053] A standard deviation control chart is generated based on the upper control line, center line, and lower control line of the standard deviation control chart, and the capacitance deviation data is used to mark points on the standard deviation control chart.

[0054] Determine whether the sample points in the standard deviation control chart are stable. If not, remove the unstable sample points and add the same number of new sample points as the unstable sample points to the capacitance deviation data. Then regenerate the standard deviation control chart until the sample points in the standard deviation control chart are stable.

[0055] Calculate the upper control line, center line, and lower control line of the mean control chart based on the mean and standard deviation of the multiple sample groups;

[0056] A mean control chart is generated based on the upper control line, center line, and lower control line of the mean control chart, and the capacitance deviation data is used to mark points on the mean control chart.

[0057] Determine whether the sample points in the mean control chart are stable. If not, remove the unstable sample points and add the same number of new sample points as the unstable sample points to the capacitance deviation data. Then regenerate the mean control chart until the sample points in the mean control chart are stable.

[0058] As described above, the upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart are calculated using the control chart method based on the capacitance deviation data. The upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart can be used to intuitively and accurately identify the abnormality of capacitance deviation.

[0059] Furthermore, determining whether the sample points in the standard deviation control chart are stable includes:

[0060] If a first preset number of consecutive sample points in the standard deviation control chart are within the range formed by the upper and lower control lines of the standard deviation control chart, then the sample points in the standard deviation control chart are determined to be stable. If not, then it is determined whether the number of sample points exceeding the range formed by the upper and lower control lines of the standard deviation control chart in a second preset number of consecutive sample points is less than or equal to a second preset value. If yes, then the sample points in the standard deviation control chart are determined to be stable. If no, then it is determined whether the number of sample points exceeding the range formed by the upper and lower control lines of the standard deviation control chart in a third preset number of consecutive sample points is less than or equal to a third preset value. If less than or equal to the third preset value, then the sample points in the standard deviation control chart are determined to be stable. If greater than the third preset value, then the sample points in the standard deviation control chart are determined to be unstable.

[0061] As described above, by judging the stability of sample points, the validity of the currently generated standard deviation control chart can be confirmed, thereby ensuring the rationality of the upper and lower control lines of the standard deviation control chart stored in the early warning threshold library.

[0062] Furthermore, the acquisition of the equivalent voltage factor, voltage deviation, sum of squares of harmonic currents, and capacitance deviation data of the reactive power compensation device includes:

[0063] Collect the phase voltage, line voltage, and instantaneous value of the outgoing line current of the reactive power compensation device connected to the bus.

[0064] The amplitude and phase of the fundamental phase voltage, the amplitude and phase of the fundamental line voltage, the amplitude and phase of the fundamental current, and the amplitude and phase of the harmonic current are calculated based on the phase voltage of the access bus, the line voltage of the access bus, and the instantaneous value of the outgoing current using Fast Fourier Transform.

[0065] The equivalent voltage factor is calculated based on the amplitude and phase of the fundamental phase voltage and the amplitude and phase of the fundamental line voltage.

[0066] Calculate the voltage deviation based on the equivalent voltage factor;

[0067] Calculate the sum of squares of the harmonic currents based on the amplitude and phase of the harmonic currents;

[0068] The capacitance deviation is calculated based on Kirchhoff's laws, using the amplitude and phase of the fundamental current and the amplitude and phase of the harmonic current.

[0069] As described above, the equivalent voltage factor is calculated based on the amplitude and phase of the fundamental phase voltage and the amplitude and phase of the fundamental line voltage. The voltage deviation is calculated based on the equivalent voltage factor. The sum of squares of harmonic currents is calculated based on the amplitude and phase of harmonic currents. The capacitance deviation is calculated based on the amplitude and phase of the fundamental current and the amplitude and phase of harmonic currents, using Kirchhoff's laws. The equivalent voltage factor, voltage deviation, sum of squares of harmonic currents, and capacitance deviation data serve as the basis for subsequent early warning, thus achieving accurate identification of abnormal states of the reactive power compensation device.

[0070] The calculation of the equivalent voltage factor based on the amplitude and phase of the fundamental phase voltage and the amplitude and phase of the fundamental line voltage specifically involves:

[0071]

[0072] In the formula, U e U represents the equivalent voltage factor. a1 U represents the effective value of the fundamental phase voltage of phase A. b1 U represents the effective value of the fundamental phase voltage of phase B. c1 U represents the effective value of the fundamental phase voltage of phase C. ab1 U represents the effective value of the fundamental line voltage between phase A and phase B. bc1 U represents the effective value of the fundamental line voltage between phase B and phase C. ca1 U0 represents the effective value of the fundamental line voltage between phase C and phase A, and U0 represents the rated voltage of the reactive power compensation device.

[0073] The calculation of voltage deviation based on the equivalent voltage factor specifically involves:

[0074]

[0075] In the formula, δ represents the voltage skewness, E(·) represents the desired function, and μ represents the average value of the equivalent voltage;

[0076] The calculation of the sum of squares of the harmonic currents based on the harmonic current amplitude and phase includes:

[0077]

[0078] In the formula, I represents the sum of squares of harmonic currents, I Ch This represents the amplitude of the h-th harmonic current;

[0079] The calculation of capacitance deviation based on Kirchhoff's laws, using the fundamental current amplitude and phase, and the harmonic current amplitude and phase, is specifically as follows:

[0080]

[0081] In the formula, This represents the h-th harmonic voltage of phase A of the parallel capacitor bus. This represents the h-th harmonic voltage of phase B of the parallel capacitor bus. This represents the phase of the h-th harmonic voltage of phase A of the parallel capacitor bus. This represents the phase of the h-th harmonic voltage of phase B of the parallel capacitor bus. This represents the h-th harmonic current flowing through phase A of the parallel capacitor bank. X represents the phase of the h-th harmonic current flowing through phase A of the parallel capacitor bank, m represents the change coefficient of the inductive reactance after a fault in phase A reactor, and X represents the phase of the inductive reactance after a fault. L X represents the fundamental rated inductive reactance before the series reactor fault, α represents the coefficient of change of capacitive reactance of phase A capacitor after the fault, and X represents the fundamental rated inductive reactance before the fault. C This indicates the fundamental rated capacitive reactance of the parallel capacitor before a fault. This represents the h-th harmonic current flowing through phase B of the parallel capacitor bank. β represents the phase of the h-th harmonic current flowing through phase B of the parallel capacitor bank, n represents the coefficient of change of inductive reactance after a fault in phase B reactor, and β represents the coefficient of change of capacitive reactance after a fault in phase B capacitor. This represents the h-th harmonic voltage of phase C of the parallel capacitor bus. This represents the h-th harmonic voltage of phase C of the parallel capacitor bus. This represents the h-th harmonic current flowing through phase C of the parallel capacitor bank. γ represents the phase of the h-th harmonic current flowing through phase C of the parallel capacitor bank, p represents the coefficient of change of inductive reactance after a fault in phase C reactor, and γ represents the coefficient of change of capacitive reactance after a fault in phase C capacitor.

[0082] As described above, by calculating the equivalent voltage factor, voltage deviation, sum of squares of harmonic currents, and capacitance deviation data, abnormalities of the reactive power compensation device can be accurately and effectively monitored.

[0083] Furthermore, the step of determining whether the reactive power compensation device has an overvoltage risk based on the equivalent voltage factor and the voltage skewness according to the early warning threshold library, and if so, outputting overvoltage early warning information includes:

[0084] The operating conditions of the reactive power compensation device are determined based on the equivalent voltage factor, and the operating conditions include abnormal operating conditions.

[0085] If the operating condition is the abnormal operating condition, then the step order is determined according to the voltage deviation, and the first overvoltage abnormal threshold and the second overvoltage abnormal threshold corresponding to the step order are obtained from the warning threshold library.

[0086] If the voltage deviation is within the range formed by the first overvoltage abnormal threshold and the second overvoltage abnormal threshold for a continuous second preset time, then an overvoltage warning threshold is output.

[0087] As described above, when the operating condition of the reactive power compensation device is determined to be abnormal based on the equivalent voltage factor, it is determined whether the voltage deviation remains within the range formed by the first and second overvoltage abnormal thresholds for a second preset duration. If so, an overvoltage warning threshold is output to assess the stability of the overvoltage state and achieve accurate overvoltage abnormality warning.

[0088] Furthermore, the step of determining whether the reactive power compensation device has an overcurrent risk based on the sum of squares of the harmonic currents according to the early warning threshold library, and if so, outputting overcurrent early warning information includes:

[0089] Obtain the overcurrent anomaly threshold from the aforementioned warning threshold library;

[0090] Determine whether the sum of squares of the harmonic currents exceeds the overcurrent abnormal threshold. If it does, output an overcurrent warning message.

[0091] As described above, based on the harmonic influence mechanism, by judging whether the sum of squares of harmonic currents exceeds the overcurrent anomaly threshold, early warning of overcurrent conditions can be effectively achieved.

[0092] Furthermore, the step of determining whether the reactive power compensation device has a risk of abnormal capacitance deviation based on the capacitance deviation data according to the early warning threshold library, and if so, outputting abnormal capacitance deviation early warning information includes:

[0093] Obtain the upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart from the warning threshold library;

[0094] The capacitance deviation data is grouped to obtain grouped capacitance deviation data.

[0095] Calculate the mean and standard deviation of the capacitance deviation data for each group;

[0096] Determine whether the mean value of any group of capacitance deviation data exceeds the range formed by the upper and lower control lines of the mean control chart. If yes, output a capacitance deviation anomaly warning message. If no, determine whether the standard deviation of any group of capacitance deviation data exceeds the range formed by the upper and lower control lines of the standard deviation control chart. If yes, output a capacitance deviation anomaly warning message.

[0097] As described above, the mean and standard deviation of the capacitance deviation data for each group are calculated, and the mean control chart and standard deviation control chart are used to identify capacitance deviation anomalies, which is intuitive and accurate.

[0098] Please refer to Figure 2 Another embodiment of the present invention provides a reactive power compensation device abnormality early warning system, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements each step of the above-described reactive power compensation device abnormality early warning method.

[0099] The above-described method and system for early warning of abnormalities in reactive power compensation devices are applicable to reactive power compensation devices, and are described below through specific embodiments:

[0100] Please refer to Figure 1 , Figures 3-6 Embodiment 1 of the present invention is as follows:

[0101] A method for early warning of abnormalities in a reactive power compensation device includes the following steps:

[0102] S1. Regularly update the early warning threshold database, such as Figure 3 As shown, specifically including S11-S19:

[0103] S11. Obtain the equivalent voltage factor and voltage deviation of the reactive power compensation device for a historical preset time period, and identify the voltage step time and step order based on the equivalent voltage factor.

[0104] In one optional implementation, the preset time period is one month, and the historical preset time period is the previous month.

[0105] The step detection of voltage step time and step order based on the equivalent voltage factor includes:

[0106] Select one moment from each of the preset historical time periods as the current moment;

[0107] If the equivalent voltage factor at the current moment is greater than 1 and less than or equal to 1.1, and the equivalent voltage factor at the previous moment is less than or equal to 1, then the current moment is marked as a voltage step moment, and the step order is 1.

[0108] If the equivalent voltage factor at the current moment is greater than 1.1, and the equivalent voltage factor at the previous moment is less than or equal to 1.1, then the current moment is marked as a voltage step moment, and the step order is 1.

[0109] If the equivalent voltage factor at the current moment is greater than 1.1, and the equivalent voltage factor at the previous moment is less than or equal to 1, then the current moment is marked as a voltage step moment, and the step order is 2.

[0110] Return to the step of sequentially selecting a moment from the historical preset time period as the current moment, until every moment in the historical preset time period has been used as the current moment.

[0111] S12. Select the voltage deviation within a first preset time period before the voltage step moment and the voltage deviation within a first preset time period after the voltage step moment from the voltage deviation of the reactive power compensation device in the historical preset time period.

[0112] In one optional implementation, the first preset duration is 12 hours.

[0113] S13. Calculate the average voltage deviation within a first preset time period before the voltage step moment, as the first overvoltage anomaly threshold corresponding to the step order, and calculate the voltage deviation within a first preset time period after the voltage step moment, as the second overvoltage anomaly threshold corresponding to the step order.

[0114] S14. Update the first overvoltage abnormality threshold and the second overvoltage abnormality threshold to the early warning threshold library.

[0115] S15. Select a target equivalent voltage factor that is less than or equal to a first preset value from the equivalent voltage factors of the reactive power compensation device in the historical preset time period, and obtain the fundamental current amplitude corresponding to the target equivalent voltage factor.

[0116] In one alternative implementation, the first preset value is 1.

[0117] S16. Calculate the overcurrent abnormality threshold based on the fundamental current amplitude, and update the overcurrent abnormality threshold to the warning threshold library.

[0118] Specifically, the overcurrent anomaly threshold calculated based on the fundamental current amplitude is as follows:

[0119]

[0120] In the formula, k represents the correction coefficient. The value of k is mainly determined by considering that the voltage peak value, including all harmonic components, should not exceed [a certain value]. Based on the relevant requirements, after equivalent conversion, it is recommended that k be taken as 0.1125, I 0i This represents the amplitude of the fundamental current on day i, and N represents the number of days in the preset time period.

[0121] S17. Obtain the capacitor deviation data of the reactive power compensation device during the historical preset time period.

[0122] To address the slow-changing characteristics of capacitor deviation in reactive power compensation devices, an abnormal state identification method based on control charts is employed for early warning.

[0123] S18. Based on the capacitance deviation data, calculate the upper and lower control lines of the standard deviation control chart and the mean control chart using the control chart method, and update the early warning threshold library with the upper and lower control lines of the standard deviation control chart and the mean control chart as capacitance deviation anomaly thresholds, specifically including S181-S189:

[0124] S181. The capacitance deviation data is grouped to obtain multiple sample groups.

[0125] Each sample group must contain at least 40 samples, and the total number of sample groups must be at least 30.

[0126] S182. Calculate the mean and standard deviation of each sample group in the multiple sample groups, and calculate the mean and standard deviation of the multiple sample groups based on the mean and standard deviation of each sample group.

[0127] Specifically, calculating the mean and standard deviation of each of the multiple sample groups involves:

[0128]

[0129]

[0130] In the formula, Let x represent the mean of the i-th sample group, n represent the number of samples in each sample group, and x represent the mean of the i-th sample group. ij S represents the j-th sample in the i-th sample group. i Let represent the standard deviation of the i-th sample group.

[0131] The specific steps for calculating the mean and standard deviation of the multiple sample groups based on the mean and standard deviation of each sample group are as follows:

[0132]

[0133] In the formula, This represents the mean of multiple sample groups, where m represents the total number of sample groups. It represents the standard deviation of multiple sample groups.

[0134] S183. Based on the standard deviations of the multiple sample groups, calculate the upper control line, center line, and lower control line of the standard deviation control chart, specifically as follows:

[0135]

[0136] In the formula, UCL S This indicates the upper control line for the standard deviation control chart; B4 represents the first coefficient; CL... S The center line of the standard deviation control chart, LCL S B3 represents the lower control line of the standard deviation control chart, and B3 represents the second coefficient.

[0137] Where n is greater than 25,

[0138] Therefore, when n = 40, B3 ≈ 0.6581, B4 ≈ 1.3419.

[0139] S184. Generate a standard deviation control chart based on the upper control line, center line, and lower control line of the standard deviation control chart, and use the capacitance deviation data to mark points on the standard deviation control chart.

[0140] S185. Determine whether the sample points in the standard deviation control chart are stable. If not, remove the unstable sample points and add the same number of new sample points as the unstable sample points to the capacitance deviation data. Then regenerate the standard deviation control chart until the sample points in the standard deviation control chart are stable. Figure 4 As shown.

[0141] The determination of whether the sample points in the standard deviation control chart are stable includes:

[0142] If a first preset number of consecutive sample points in the standard deviation control chart are within the range formed by the upper and lower control lines of the standard deviation control chart, then the sample points in the standard deviation control chart are determined to be stable. If not, then it is determined whether the number of sample points exceeding the range formed by the upper and lower control lines of the standard deviation control chart in a second preset number of consecutive sample points is less than or equal to a second preset value. If yes, then the sample points in the standard deviation control chart are determined to be stable. If no, then it is determined whether the number of sample points exceeding the range formed by the upper and lower control lines of the standard deviation control chart in a third preset number of consecutive sample points is less than or equal to a third preset value. If less than or equal to the third preset value, then the sample points in the standard deviation control chart are determined to be stable. If greater than the third preset value, then the sample points in the standard deviation control chart are determined to be unstable.

[0143] In one optional implementation, the first preset quantity is 25, the second preset quantity is 35, the second preset value is 1, the third preset quantity is 100, and the third preset value is 2.

[0144] S186. Calculate the upper control line, center line, and lower control line of the mean control chart based on the mean and standard deviation of the multiple sample groups, specifically as follows:

[0145]

[0146] In the formula, A3 represents the upper control line of the mean control chart, and A3 represents the third coefficient.

[0147] Where n is greater than 25,

[0148] S187. Generate a mean control chart based on the upper control line, center line and lower control line of the mean control chart, and use the capacitance deviation data to mark points on the mean control chart.

[0149] S188. Determine whether the sample points in the mean control chart are stable. If not, remove the unstable sample points and add new sample points of the same number as the unstable sample points to the capacitance deviation data, and regenerate the mean control chart until the sample points in the mean control chart are stable.

[0150] The specific method for determining whether the sample points in the mean control chart are stable is the same as the method for determining whether the sample points in the standard deviation control chart are stable, and will not be repeated here.

[0151] S189. Update the warning threshold library with the upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart as the capacitance deviation abnormality thresholds.

[0152] like Figure 6 As shown, Figure 6 A schematic diagram of a control chart is provided, which includes an upper control line, a middle control line, and a lower control line.

[0153] S19. At each preset time interval, return to execute S11.

[0154] Specifically, S11 is executed every month, meaning the warning threshold library is updated monthly.

[0155] S2. Obtain the equivalent voltage factor, voltage deviation, sum of squares of harmonic currents, and capacitance deviation data (i.e., advanced statistical indicators) of the reactive power compensation device, such as... Figure 3 As shown, specifically including S21-S26:

[0156] S21. Collect the phase voltage, line voltage, and instantaneous value of the outgoing current of the reactive power compensation device connected to the bus.

[0157] S22. Based on the phase voltage of the access bus, the line voltage of the access bus, and the instantaneous value of the outgoing current, calculate the amplitude and phase of the fundamental phase voltage, the amplitude and phase of the fundamental line voltage, the amplitude and phase of the fundamental current, and the amplitude and phase of the harmonic current (i.e., basic state quantity indicators) using Fast Fourier Transform.

[0158] S23. Calculate the equivalent voltage factor based on the fundamental phase voltage amplitude and phase, and the fundamental line voltage amplitude and phase, specifically as follows:

[0159]

[0160] In the formula, U e U represents the equivalent voltage factor. a1 U represents the effective value of the fundamental phase voltage of phase A. b1 U represents the effective value of the fundamental phase voltage of phase B. c1 U represents the effective value of the fundamental phase voltage of phase C. ab1 U represents the effective value of the fundamental line voltage between phase A and phase B. bc1 U represents the effective value of the fundamental line voltage between phase B and phase C. ca1 U0 represents the effective value of the fundamental line voltage between phase C and phase A, and U0 represents the rated voltage of the reactive power compensation device.

[0161] S24. Calculate the voltage deviation based on the equivalent voltage factor, specifically as follows:

[0162]

[0163] In the formula, δ represents the voltage skewness, E(·) represents the desired function, and μ represents the average value of the equivalent voltage.

[0164] Voltage skewness is a higher-order statistic describing the symmetry of the distribution of voltage values. A negative voltage skewness value indicates that the sample is skewed to the left; a value of 0 indicates that the sample is symmetrically distributed; and a positive value indicates that the sample is skewed to the right. The larger the absolute value, the more severe the deviation. Skewness has several definitions; the skewness of a normal distribution and all symmetrical distributions is 0.

[0165] S25. Calculate the sum of squares of the harmonic currents based on the amplitude and phase of the harmonic currents, such as... Figure 5 As shown, specifically:

[0166]

[0167] In the formula, I represents the sum of squares of harmonic currents, I Ch This represents the amplitude of the h-th harmonic current.

[0168] S26. Based on the amplitude and phase of the fundamental current and the amplitude and phase of the harmonic current, the capacitance deviation is calculated using Kirchhoff's laws. Specifically, a simultaneous equation is established using the fundamental current and a certain high-content harmonic, as follows:

[0169]

[0170] In the formula, This represents the h-th harmonic voltage of phase A of the parallel capacitor bus. This represents the h-th harmonic voltage of phase B of the parallel capacitor bus, where h = 1, 2, 3… This represents the phase of the h-th harmonic voltage of phase A of the parallel capacitor bus. This represents the phase of the h-th harmonic voltage of phase B of the parallel capacitor bus. This represents the h-th harmonic current flowing through phase A of the parallel capacitor bank. X represents the phase of the h-th harmonic current flowing through phase A of the parallel capacitor bank, m represents the change coefficient of the inductive reactance after a fault in phase A reactor, and X represents the phase of the inductive reactance after a fault. L X represents the fundamental rated inductive reactance before the series reactor fault, α represents the coefficient of change of capacitive reactance of phase A capacitor after the fault, and X represents the fundamental rated inductive reactance before the fault. C This indicates the fundamental rated capacitive reactance of the parallel capacitor before a fault. This represents the h-th harmonic current flowing through phase B of the parallel capacitor bank. When h = 1, it is the fundamental current. β represents the phase of the h-th harmonic current flowing through phase B of the parallel capacitor bank, n represents the coefficient of change of inductive reactance after a fault in phase B reactor, and β represents the coefficient of change of capacitive reactance after a fault in phase B capacitor. This represents the h-th harmonic voltage of phase C of the parallel capacitor bus. This represents the h-th harmonic voltage of phase C of the parallel capacitor bus. This represents the h-th harmonic current flowing through phase C of the parallel capacitor bank. γ represents the phase of the h-th harmonic current flowing through phase C of the parallel capacitor bank, p represents the coefficient of change of inductive reactance after a fault in phase C reactor, and γ represents the coefficient of change of capacitive reactance after a fault in phase C capacitor.

[0171] Where α, β, and γ represent the three-phase capacitance deviations to be determined. At the h-th harmonic, the capacitive reactance X of the parallel capacitors... Ch =X C / h, series reactor reactance X Lh =hX L .

[0172] S3. Based on the warning threshold library, determine whether the reactive power compensation device has an overvoltage risk according to the equivalent voltage factor and the voltage deviation. If so, output overvoltage warning information, such as... Figure 5 As shown, specifically including S31-S33:

[0173] S31. Determine the operating condition of the reactive power compensation device based on the equivalent voltage factor. The operating condition includes abnormal operating condition and normal operating condition. The abnormal operating condition includes a first abnormal operating condition, a second abnormal operating condition, and a third abnormal operating condition.

[0174] Specifically, the national standard GB / T 11024.1-2019 specifies the long-term operating voltage of parallel capacitors. The equipment's withstand capability depends on the amplitude and duration of the power frequency overvoltage. If the equivalent voltage factor is within the range of 1 to 1.1, the reactive power compensation device is determined to be in the first abnormal operating condition. If the equivalent voltage factor is within the range of 1.1 to 1.15, the reactive power compensation device is determined to be in the second abnormal operating condition. If the equivalent voltage factor is 1.15, the reactive power compensation device is determined to be in the third abnormal operating condition. If none of the above ranges are met, the reactive power compensation device is determined to be in the normal operating condition.

[0175] S32. If the operating condition is the abnormal operating condition, then the step number is determined according to the voltage deviation, and the first overvoltage abnormal threshold and the second overvoltage abnormal threshold corresponding to the step number are obtained from the warning threshold library.

[0176] S33. Determine whether the voltage deviation is within the range formed by the first overvoltage abnormal threshold and the second overvoltage abnormal threshold for a continuous second preset time. If so, output the overvoltage warning threshold.

[0177] In one alternative implementation, the second preset duration is 15 minutes.

[0178] In one alternative implementation, after S31, the following may also be included:

[0179] If the operating condition is the first abnormal operating condition accumulated for a third preset time, then an overvoltage alarm message will be output;

[0180] If the operating condition is the second abnormal operating condition accumulated for the fourth preset time, then an overvoltage alarm message will be output;

[0181] If the operating condition is the third abnormal operating condition, an overvoltage alarm message will be output.

[0182] In one optional implementation, the third preset duration is 12 hours, and the fourth preset duration is 5 minutes. This not only provides early warning for reactive power compensation devices exhibiting signs of overvoltage anomalies, but also alerts reactive power compensation devices that have already experienced overvoltage anomalies, ensuring that staff can promptly address the fault.

[0183] S4. Based on the warning threshold library, determine whether the reactive power compensation device has an overcurrent risk according to the sum of squares of the harmonic currents. If so, output overcurrent warning information, such as... Figure 5 As shown, specifically including S41-S42:

[0184] S41. Obtain the overcurrent abnormal threshold from the warning threshold library.

[0185] S42. Determine whether the sum of squares of the harmonic currents exceeds the overcurrent abnormal threshold. If it does, output an overcurrent warning message.

[0186] The national standard GB / T 11024.1-2019 stipulates that a capacitor unit should be able to operate continuously at a current 1.3 times the root mean square value of the current generated by the unit at its rated sinusoidal voltage and rated frequency. In an optional embodiment, it may further include:

[0187] The system acquires the effective current value of the reactive power compensation device and determines whether the effective current value exceeds a preset multiple of the rated current. If so, an overcurrent alarm message is output. This provides timely overcurrent warnings, facilitating prompt maintenance.

[0188] S5. Based on the warning threshold library, determine whether the reactive power compensation device has a risk of abnormal capacitance deviation according to the capacitance deviation data. If so, output abnormal capacitance deviation warning information, such as... Figure 5 As shown, specifically including S51-S54:

[0189] S51. Obtain the upper and lower control lines of the standard deviation control chart and the upper and lower control lines of the mean control chart from the warning threshold library.

[0190] S52. The capacitance deviation data is grouped to obtain the grouped capacitance deviation data.

[0191] S53. Calculate the mean and standard deviation of the capacitance deviation data for each group.

[0192] S54. Determine whether the mean value of any group of capacitance deviation data exceeds the range formed by the upper and lower control lines of the mean control chart. If yes, output a capacitance deviation abnormality warning message. If no, determine whether the standard deviation of any group of capacitance deviation data exceeds the range formed by the upper and lower control lines of the standard deviation control chart. If yes, output a capacitance deviation abnormality warning message.

[0193] This invention constructs a warning threshold library, which can be automatically and periodically updated through data correlation analysis and other means to ensure accurate warning of abnormal states. It also proposes an overvoltage warning technology for reactive power compensation devices based on statistical learning. By judging whether the voltage deviation is stable within a certain threshold, the stability of the overvoltage state is assessed. Based on actual operating data, abnormal thresholds for two types of voltage step amplitudes in adjacent / indirect operating intervals are statistically learned, achieving accurate warning of overvoltage states. Furthermore, an overcurrent warning technology for reactive power compensation devices based on the harmonic influence mechanism is proposed. By deriving the capacitor overcurrent verification formula under harmonic conditions, the allowable level of harmonic current is obtained, achieving early warning of overcurrent states. Finally, a capacitor deviation warning technology for reactive power compensation devices based on statistical control charts is proposed. By combining recent historical capacitor deviation monitoring data to learn abnormal thresholds for capacitor deviation trends, abnormal states of capacitor deviation trends are accurately identified.

[0194] Please refer to Figure 2 Embodiment two of the present invention is as follows:

[0195] A reactive power compensation device abnormality early warning system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps of the reactive power compensation device abnormality early warning method in Embodiment 1.

[0196] In summary, this invention provides a method and system for early warning of abnormalities in reactive power compensation devices. It periodically updates the early warning threshold library. Based on this library, it determines whether the reactive power compensation device faces overvoltage risk based on the equivalent voltage factor and voltage skewness. If so, it outputs an overvoltage warning. It also determines whether the reactive power compensation device faces overcurrent risk based on the sum of squared harmonic currents. If so, it outputs an overcurrent warning. Finally, it determines whether the reactive power compensation device faces capacitor deviation anomaly risk based on capacitor deviation data. If so, it outputs a capacitor deviation anomaly warning. This method provides early warning of overvoltage risk based on the equivalent voltage factor and voltage skewness, overcurrent risk based on the sum of squared harmonic currents, and capacitor deviation anomaly risk based on capacitor deviation data. This approach more effectively and reliably monitors overvoltage, overcurrent, and capacitor deviation risks in reactive power compensation devices. Anomalies are detected and warnings are issued. The warning threshold library is updated regularly to ensure that the thresholds are updated in real time based on recent historical data, guaranteeing accurate warnings of abnormal risks and achieving more precise and reliable warnings for reactive power compensation devices. Furthermore, the equivalent voltage factor and voltage deviation of the reactive power compensation devices over a preset historical time period are obtained. Overvoltage anomaly thresholds are calculated and updated to the warning threshold library based on these values. Overcurrent anomaly thresholds are calculated based on the fundamental current amplitude corresponding to the target equivalent voltage factor and updated to the warning threshold library. Finally, capacitor deviation anomaly thresholds are calculated using control charts based on the capacitor deviation data of the reactive power compensation devices over a preset historical time period. These upper and lower control lines of the standard deviation control chart and the mean control chart are used as capacitor deviation anomaly thresholds and updated to the warning threshold library, thus establishing more scientifically sound and reasonable warning thresholds for overvoltage, overcurrent, and capacitor deviation anomalies.

[0197] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for early warning of abnormality of a reactive power compensation device, characterized by, The method comprises the steps of: periodically updating a warning threshold library; obtaining equivalent voltage factor, voltage skewness, harmonic current square sum and capacitance deviation data of the reactive power compensation device; judging whether the reactive power compensation device has overvoltage risk based on the equivalent voltage factor and the voltage skewness according to the warning threshold library, and if yes, outputting overvoltage warning information; judging whether the reactive power compensation device has overcurrent risk based on the harmonic current square sum according to the warning threshold library, and if yes, outputting overcurrent warning information; judging whether the reactive power compensation device has capacitance deviation abnormal risk based on the capacitance deviation data according to the warning threshold library, and if yes, outputting capacitance deviation abnormal warning information; the periodically updating a warning threshold library comprises: obtaining equivalent voltage factor and voltage skewness of the reactive power compensation device in a historical preset time period, and identifying voltage step time and step order based on the equivalent voltage factor; selecting voltage skewness in a first preset time period before the voltage step time and voltage skewness in a first preset time period after the voltage step time from the voltage skewness of the reactive power compensation device in the historical preset time period; calculating the average value of the voltage skewness in the first preset time period before the voltage step time as a first overvoltage abnormal threshold corresponding to the step order, and calculating the voltage skewness in the first preset time period after the voltage step time as a second overvoltage abnormal threshold corresponding to the step order; updating the first overvoltage abnormal threshold and the second overvoltage abnormal threshold to the warning threshold library; selecting a target equivalent voltage factor less than or equal to a first preset value from the equivalent voltage factor of the reactive power compensation device in the historical preset time period, and obtaining fundamental current amplitude corresponding to the target equivalent voltage factor; calculating an overcurrent abnormal threshold based on the fundamental current amplitude, and updating the overcurrent abnormal threshold to the warning threshold library; obtaining capacitance deviation data of the reactive power compensation device in the historical preset time period; calculating upper control line and lower control line of a standard deviation control chart and upper control line and lower control line of a mean value control chart based on the capacitance deviation data using a control chart method, and updating the upper control line and the lower control line of the standard deviation control chart and the upper control line and the lower control line of the mean value control chart to the warning threshold library as capacitance deviation abnormal threshold; returning to execute the step of obtaining equivalent voltage factor and voltage skewness of the reactive power compensation device in a historical preset time period every interval of the preset time period.

2. The method according to claim 1, characterized in that, The calculating upper control line and lower control line of a standard deviation control chart and upper control line and lower control line of a mean value control chart based on the capacitance deviation data using a control chart method comprises: grouping the capacitance deviation data to obtain multiple sample groups; calculating the mean value and the standard deviation of each sample group in the multiple sample groups, and calculating the mean value and the standard deviation of the multiple sample groups according to the mean value and the standard deviation of each sample group; calculating upper control line, center line and lower control line of a standard deviation control chart based on the standard deviation of the multiple sample groups; generating a standard deviation control chart based on the upper control line, the center line and the lower control line of the standard deviation control chart, and using the capacitance deviation data to plot points in the standard deviation control chart; determining whether the sample points in the standard deviation control chart are stable, if not, removing the unstable sample points, supplementing new sample points equal in number to the unstable sample points into the capacitance deviation data, and regenerating the standard deviation control chart until the sample points in the standard deviation control chart are stable; calculating the upper control line, the center line and the lower control line of the mean control chart based on the mean and the standard deviation of the plurality of sample groups; generating a mean control chart based on the upper control line, the center line and the lower control line of the mean control chart, and using the capacitance deviation data to plot points in the mean control chart; determining whether the sample points in the mean control chart are stable, if not, removing the unstable sample points, supplementing new sample points equal in number to the unstable sample points into the capacitance deviation data, and regenerating the mean control chart until the sample points in the mean control chart are stable.

3. The method according to claim 2, characterized in that, The determination of whether the sample points in the standard deviation control chart are stable comprises: determining whether a first preset number of consecutive sample points in the standard deviation control chart are within a range formed by the upper control line and the lower control line of the standard deviation control chart, if yes, determining that the sample points in the standard deviation control chart are stable, if not, determining whether a number of sample points exceeding the range formed by the upper control line and the lower control line of the standard deviation control chart in a second preset number of consecutive sample points is less than or equal to a second preset value, if yes, determining that the sample points in the standard deviation control chart are stable, if not, determining whether a number of sample points exceeding the range formed by the upper control line and the lower control line of the standard deviation control chart in a third preset number of consecutive sample points is less than or equal to a third preset value, if less than or equal to the third preset value, determining that the sample points in the standard deviation control chart are stable, if greater than the third preset value, determining that the sample points in the standard deviation control chart are not stable.

4. The method of claim 1, wherein the method further comprises: The acquisition of the equivalent voltage factor, the voltage skewness, the harmonic current square sum and the capacitance deviation data of the reactive power compensation device comprises: collecting phase voltages of an access bus of the reactive power compensation device, line voltages of the access bus and instantaneous values of outgoing line currents; calculating fundamental wave phase voltage amplitudes and phases, fundamental wave line voltage amplitudes and phases, fundamental wave current amplitudes and phases and harmonic current amplitudes and phases based on fast Fourier transform according to the phase voltages of the access bus, the line voltages of the access bus and the instantaneous values of the outgoing line currents; calculating the equivalent voltage factor according to the fundamental wave phase voltage amplitudes and phases and the fundamental wave line voltage amplitudes and phases; calculating the voltage skewness based on the equivalent voltage factor; calculating the harmonic current square sum based on the harmonic current amplitudes and phases; calculating the capacitance deviation based on the fundamental wave current amplitudes and phases and the harmonic current amplitudes and phases based on Kirchhoff's law.

5. The method of claim 4, wherein the method further comprises: The calculation of the equivalent voltage factor according to the fundamental wave phase voltage amplitudes and phases and the fundamental wave line voltage amplitudes and phases specifically comprises: ； wherein U e Veff represents the equivalent voltage factor, U a1 Veff represents the fundamental phase voltage effective value of phase A, U b1 Veff represents the fundamental phase voltage effective value of phase B, U c1 Veff represents the fundamental phase voltage effective value of phase C, U ab1 Veff represents the fundamental line voltage effective value between phase A and phase B, U bc1 Veff represents the fundamental line voltage effective value between phase B and phase C, U ca1 Veff represents the fundamental line voltage effective value between phase C and phase A, U 0 represents the rated voltage of the reactive power compensation device; The calculating voltage skew based on the equivalent voltage factor specifically comprises: ； wherein denotes the voltage skew, denotes the expected function, denotes the average of the equivalent voltages; The calculating harmonic current square sum based on the harmonic current amplitude and phase comprises: ； wherein denotes the sum of the squares of the harmonic currents, denotes the amplitude of the hth harmonic current; The calculating capacitance deviation based on the fundamental current amplitude and phase and the harmonic current amplitude and phase based on Kirchhoff's law specifically comprises: ； ； ； wherein, VshA represents the hth harmonic voltage of the shunt capacitor bus A phase, VshB represents the hth harmonic voltage of the shunt capacitor bus B phase, φshA represents the phase of the hth harmonic voltage of the shunt capacitor bus A phase, φshB represents the phase of the hth harmonic voltage of the shunt capacitor bus B phase, IshA represents the hth harmonic current flowing through the shunt capacitor device A phase, φishA represents the phase of the hth harmonic current flowing through the shunt capacitor device A phase, m represents the change coefficient of the inductance after the A phase reactor fault, X L XshA represents the base rated capacitive reactance before the shunt capacitor fault, m represents the change coefficient of the capacitive reactance after the A phase capacitor fault, X C XshB represents the base rated capacitive reactance before the shunt capacitor fault, IshB represents the hth harmonic current flowing through the shunt capacitor device B phase, φishB represents the phase of the hth harmonic current flowing through the shunt capacitor device B phase, n represents the change coefficient of the inductance after the B phase reactor fault, n represents the change coefficient of the capacitive reactance after the B phase capacitor fault, VshC represents the hth harmonic voltage of the shunt capacitor bus C phase, VshC represents the hth harmonic voltage of the shunt capacitor bus C phase, IshC represents the hth harmonic current flowing through the shunt capacitor device C phase, φishC represents the phase of the hth harmonic current flowing through the shunt capacitor device C phase, p represents the change coefficient of the inductance after the C phase reactor fault, p represents the change coefficient of the capacitive reactance after the C phase capacitor fault.

6. The method of claim 1, wherein the method further comprises: The judging whether the overvoltage risk exists in the reactive power compensation device based on the early warning threshold library according to the equivalent voltage factor and the voltage skew, and outputting overvoltage early warning information if yes, comprises: Determining the working condition of the reactive power compensation device according to the equivalent voltage factor, wherein the working condition comprises an abnormal working condition; If the working condition is the abnormal working condition, determining the step number according to the voltage skew, and obtaining the first overvoltage abnormal threshold and the second overvoltage abnormal threshold corresponding to the step number from the early warning threshold library; Judging whether the voltage skew is continuously in the range formed by the first overvoltage abnormal threshold and the second overvoltage abnormal threshold for a second preset time length, and outputting overvoltage early warning threshold if yes.

7. The method of claim 1, wherein the method further comprises: The judging whether the overcurrent risk exists in the reactive power compensation device based on the early warning threshold library according to the harmonic current square sum, and outputting overcurrent early warning information if yes, comprises: Obtaining the overcurrent abnormal threshold from the early warning threshold library; Judging whether the harmonic current square sum exceeds the overcurrent abnormal threshold, and outputting overcurrent early warning information if yes.

8. The method of claim 1, wherein the method further comprises: The judging whether the capacitance deviation abnormal risk exists in the reactive power compensation device based on the early warning threshold library according to the capacitance deviation data, and outputting capacitance deviation abnormal early warning information if yes, comprises: Obtaining the upper control line and the lower control line of the standard deviation control chart and the upper control line and the lower control line of the mean value control chart from the early warning threshold library; Grouping the capacitance deviation data to obtain grouped capacitance deviation data; Calculating the mean value and the standard deviation of the capacitance deviation data of each group; Judging whether the mean value of the capacitance deviation data of any group exceeds the range formed by the upper control line and the lower control line of the mean value control chart, and outputting capacitance deviation abnormal early warning information if yes, or judging whether the standard deviation of the capacitance deviation data of any group exceeds the range formed by the upper control line and the lower control line of the standard deviation control chart, and outputting capacitance deviation abnormal early warning information if yes.

9. A system for early warning of abnormality in a reactive power compensation device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the computer program to realize each step in the reactive power compensation device abnormal early warning method of any one of claims 1 to 8.

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