Rapid fault early warning method and system for large-scale power distribution station

Abstract

The invention relates to the technical field of power distribution station fault early warning, in particular to a rapid fault early warning method and system for a large-scale power distribution station, and the method comprises the steps: comparing the maximum amplitude difference between electromagnetic wave signals of any two sensors, combining the interference coefficient mean value of the electromagnetic wave signals in all sensors, determining the amplitude deviation, and determining the maximum amplitude difference; the maximum partial discharge signal is screened out by combining the distance between any two sensors; the partial discharge index is determined by analyzing the energy of the maximum partial discharge signal in each frequency interval and the dispersion degree of the maximum amplitude of the electromagnetic wave signals in all the sensors in each target period and combining the proportion of the number of all the target periods in the total number of the power frequency periods. And performing fault early warning on the to-be-tested switch cabinet in the large-scale power distribution station. The invention aims to improve the detection precision of the insulation fault of the switch cabinet in the large-scale power distribution station.

Description

Technical Field

[0001] The present application relates to the technical field of fault early warning for distribution substations, and particularly to a method and system for rapid fault early warning of large-scale distribution substations. Background Art

[0002] As the core part of the power distribution network, after a large number of distributed power sources and energy storage devices are connected to the grid, the operating characteristics of large-scale distribution substations have changed greatly, posing higher requirements for their fault detection. The switchgear is a key device for power transmission and distribution in large-scale distribution substations. After an insulation breakdown fault occurs in the switchgear, it will first cause the circuit breaker to trip, resulting in a power outage event. In severe cases, it will also damage power equipment and cause accidents such as explosion and fire, seriously affecting the operation reliability of the power grid. Therefore, for the insulation faults of switchgears in large-scale distribution substations, realizing rapid fault early warning and fault elimination is an important support for ensuring the safety of power equipment and improving the safe and stable operation of the power grid.

[0003] Partial discharge is a precursor and important warning information for insulation breakdown faults. Detecting partial discharge in switchgears of large-scale distribution substations is an effective method for insulation state assessment and insulation fault diagnosis. The ultra-high frequency method realizes effective detection of partial discharge by measuring the electromagnetic waves generated during the discharge process, and is a commonly used technical means for detecting partial discharge in switchgears in the industry. There are many types and quantities of devices connected to the switchgears in large-scale distribution substations, and the corresponding operating state changes are relatively complex, resulting in a large amount of electromagnetic interference in the electromagnetic environment where the switchgears are located, making the signals obtained by the ultra-high frequency method measurement contain a lot of interference signals. At the same time, when the ultra-high frequency method is currently used in the industry to detect partial discharge, the influence of the discharge position on partial discharge detection is ignored, reducing the accuracy of insulation fault detection for switchgears in large-scale distribution substations. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present application is to provide a method and system for rapid fault early warning of large-scale distribution substations, and the specific technical solutions adopted are as follows:

[0005] In the first aspect, an embodiment of the present application provides a method for rapid fault early warning of large-scale distribution substations, and the method includes the following steps:

[0006] Install a plurality of ultra-high frequency sensors on the switchgear to be tested in the large-scale distribution substation, collect the electromagnetic wave signals, their maximum amplitudes and phases in each ultra-high frequency sensor within each power frequency cycle, and denote the ultra-high frequency sensors as sensors;

[0007] Analyze the differences between the phases corresponding to the maximum amplitudes of the electromagnetic wave signals in each sensor within each power frequency cycle and a preset first phase and a preset second phase respectively, and combine the maximum amplitudes to determine the interference coefficient of the electromagnetic wave signals in each sensor;

[0008] At each power frequency period, compare the difference in the maximum amplitudes between the electromagnetic wave signals of any two sensors, and combine the average interference coefficient of the electromagnetic wave signals among all sensors to determine the amplitude deviation between the electromagnetic wave signals of any two sensors at each power frequency period.

[0009] By analyzing the distance between any two sensors and combining the amplitude deviation, determine the comprehensive deviation of each power frequency period to screen out the target periods from all power frequency periods, compare the maximum amplitudes of the electromagnetic wave signals among all sensors within each target period, and screen out the maximum partial discharge signals within each target period from the electromagnetic wave signals.

[0010] Divide the frequency domain of the maximum partial discharge signal into multiple frequency intervals, and determine the partial discharge energy of each target period by analyzing the energy of the maximum partial discharge signal within each frequency interval and the degree of dispersion of the maximum amplitudes of the electromagnetic wave signals among all sensors within each target period.

[0011] Based on the partial discharge energy of all target periods and the proportion of the number of all target periods in the total number of power frequency periods, determine the partial discharge index of the switchgear to be measured, and conduct fault warning on the switchgear to be measured in a large-scale substation.

[0012] Preferably, the expression of the interference coefficient of the electromagnetic wave signal in each sensor is: In the formula, F k represents the interference coefficient of the electromagnetic wave signal in sensor k; min k,t represents the minimum value of the differences between the phases corresponding to the maximum amplitude of the electromagnetic wave signal in sensor k at power frequency period t and a preset first phase and a preset second phase; A k,t represents the maximum amplitude of the electromagnetic wave signal in sensor k at power frequency period t; T represents the number of all power frequency periods; norm[] represents the normalization function; γ represents a preset constant greater than 1.

[0013] Preferably, the expression of the amplitude deviation between the electromagnetic wave signals of any two sensors at each power frequency period is: In the formula, represents the amplitude deviation between the electromagnetic wave signals of sensor i and sensor j within power frequency period t; L t represents the average interference coefficient of the electromagnetic wave signals among all sensors within power frequency period t; represents the difference in the maximum amplitudes between the electromagnetic wave signals of sensor i and sensor j within power frequency period t.

[0014] Preferably, the method for determining the comprehensive deviation of each power frequency period is:

[0015] Calculate the product of the amplitude deviation between the electromagnetic wave signals of any two sensors within each power frequency period and the distance between the corresponding sensors, and use the cumulative value of the products between all sensors within each power frequency period as the comprehensive deviation of each power frequency period.

[0016] Preferably, the method for determining the target period is as follows:

[0017] Calculate the mean value of the comprehensive deviations of all power frequency periods, denoted as the deviation mean value, and use the power frequency periods corresponding to the comprehensive deviation being greater than or equal to the deviation mean value as the target periods.

[0018] Preferably, the maximum partial discharge signal within each target period is the electromagnetic wave signal corresponding to the maximum value among the maximum amplitudes of all electromagnetic wave signals within each target period.

[0019] Preferably, the expression for the partial discharge energy of each target period is as follows: H z represents the partial discharge energy of the target period z; CV z represents the degree of dispersion of the maximum amplitudes of all electromagnetic wave signals within the target period z; w z,n represents the preset weight of the maximum partial discharge signal within the target period z in the frequency interval n, where w z,1 +w z,2 +w z,3 +w z,4 =1; E z,n represents the energy of the maximum partial discharge signal within the target period z in the frequency interval; N z represents the number of all frequency intervals of the maximum partial discharge signal within the target period z; ε represents a preset constant greater than 0.

[0020] Preferably, the method for determining the partial discharge index of the switchgear under test is as follows:

[0021] Calculate the cumulative sum of the partial discharge energies of all target periods, and use the product of the proportion of the number of all target periods in the total number of power frequency periods and the cumulative sum as the partial discharge index of the switchgear under test.

[0022] Preferably, the fault warning for the switchgear under test in a large-scale distribution substation includes:

[0023] According to the method for obtaining the partial discharge index, obtain the partial discharge indices of a preset number of switchgear cabinets without insulation faults, and record the maximum value among the partial discharge indices as the absolute fault threshold. If the partial discharge index of the switchgear cabinet to be tested is greater than the absolute fault threshold, issue a fault warning for the large-scale distribution substation to be tested; otherwise, do not issue a fault warning. In a second aspect, an embodiment of the present application also provides a fault rapid warning system for a large-scale distribution substation, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned fault rapid warning methods for a large-scale distribution substation are implemented.

[0024] The present application has at least the following beneficial effects:

[0025] By analyzing the difference between the maximum replication of the electromagnetic wave signal and the phase of the wave crest and wave trough, the present application constructs an interference coefficient, which reflects the degree of electromagnetic interference suffered by the electromagnetic wave signal generated by the alternating voltage, and helps to exclude the interference caused by electromagnetic interference during the partial discharge detection process; further, by comparing the difference in the maximum amplitudes between the electromagnetic wave signals in different sensors and combining the interference coefficient, an amplitude deviation is obtained, which improves the detection ability for weak partial discharges; further, based on the amplitude deviation, a comprehensive deviation is obtained, and the maximum partial discharge signal is screened out from all construction periods. By analyzing the energy of the maximum partial discharge signal in each frequency interval and combining the frequency of the partial discharge, a partial discharge index is constructed, which provides a quantitative index for fault warning, comprehensively considers the position of the partial discharge and the influence of electromagnetic interference on the partial discharge detection, and improves the accuracy of the insulation fault detection of the switchgear cabinet in the large-scale distribution substation. By analyzing the difference and energy distribution between the electromagnetic wave signals in the sensors at different positions on the switchgear cabinet, the present application can quickly and accurately detect the insulation fault in the switchgear cabinet, and improve the accuracy of the insulation fault detection of the switchgear cabinet in the large-scale distribution substation. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is a flowchart of the steps of a fault rapid warning method for a large-scale distribution substation provided by an embodiment of the present application;

[0028] Figure 2 It is a schematic diagram of the partial discharge energy extraction process provided by an embodiment of the present application. Detailed Implementation Manner

[0029] In order to further elaborate on the technical means and effects adopted by this application to achieve the intended invention purpose, the following will, in combination with the accompanying drawings and preferred embodiments, elaborate in detail on a fault rapid warning method and system for a large-scale power distribution station proposed according to this application, its specific implementation manner, structure, features, and effects. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs.

[0031] The following will specifically describe the specific solution of a fault rapid warning method and system for a large-scale power distribution station provided by this application in combination with the accompanying drawings.

[0032] Please refer to Figure 1 , which shows the step flow chart of a fault rapid warning method for a large-scale power distribution station provided by an embodiment of this application. The method includes the following steps:

[0033] Step S1: Install a plurality of ultra-high frequency sensors on the switchgear to be measured in the large-scale power distribution station, and collect the electromagnetic wave signals, their maximum amplitudes, and phases in each ultra-high frequency sensor within each power frequency cycle.

[0034] To improve the accuracy of partial discharge detection and considering the actual installation difficulty at the same time, install an ultra-high frequency sensor (UHF) on the inner sides of both sides and the back of the switchgear to collect the electromagnetic wave signals, as well as the phases and maximum amplitudes of the electromagnetic wave signals in each ultra-high frequency sensor (UHF) within each power frequency cycle. Among them, when measuring the electromagnetic wave signals in the switchgear of the large-scale power distribution station, the installation positions on different installation surfaces can be determined according to the actual installation difficulty. In this embodiment, the installation position of the ultra-high frequency sensor (UHF) is the geometric center of each rectangular installation surface on the switchgear. The ultra-high frequency sensor (UHF) uses an ultra-high frequency partial discharge detector, and the ultra-high frequency sensor (UHF) transmits the measured electromagnetic wave signals to the upper computer.

[0035] It should be added that for the convenience of expression, the ultra-high frequency sensor (UHF) will be uniformly abbreviated as the sensor in the following content.

[0036] In addition, it should be understood that during the process of collecting electromagnetic wave signals in this embodiment, the collection period is set to one power frequency period. The power frequency period is a well-known technology, and the duration of the power frequency period is 0.02 s. In this embodiment, electromagnetic wave signals within 500 power frequency periods are collected, that is, electromagnetic wave signals for 10 s are collected in total. In the actual application process, the implementer can also set the collection period and collection duration according to the specific situation by himself / herself, and this embodiment does not make special restrictions.

[0037] It should be noted that the electromagnetic wave signals collected by the ultra-high frequency sensor in this embodiment are electromagnetic pulse signals generated by the alternating voltage in the large-scale distribution substation in the ultra-high frequency sensor. Electromagnetic interference refers to the electromagnetic interference generated when circuit breakers, contactors, transformers, etc. in the large-scale distribution substation start or switch.

[0038] Step S2: Analyze the degree of electromagnetic interference suffered by the electromagnetic wave signals in the sensor, and determine the partial discharge energy of each target period.

[0039] The electromagnetic interference characteristics generated by different types of power equipment in the switchgear of a large-scale distribution substation under different working states are different. For example, equipment such as circuit breakers, contactors, and transformers will generate electromagnetic interference of different intensities when starting or switching. The intensity of the interference source determines its influence on the partial discharge signal. If the interference source is very strong, it may significantly reduce the signal-to-noise ratio of the electromagnetic wave signals of the sensor. In addition, the frequency range and distribution of the high-frequency harmonics of the electromagnetic interference signal will also have different effects on the partial discharge signal. If the high-frequency harmonics of the interference signal are concentrated in the frequency band of the partial discharge signal, the influence on the partial discharge detection will be more serious.

[0040] Therefore, by analyzing the degree of electromagnetic interference suffered by the electromagnetic wave signals in the sensor, the partial discharge energy of each target period is determined, and the specific process is as follows:

[0041] S201: Analyze the differences between the phases corresponding to the maximum amplitudes of the electromagnetic wave signals in each sensor within each power frequency period respectively and the preset first phase and the preset second phase, and combine the maximum amplitudes to determine the interference coefficient of the electromagnetic wave signals in each sensor.

[0042] The harmonics generated by the change of the working state of the power equipment in the switchgear of a large-scale distribution substation have a small amplitude at ultra-high frequencies, but a relatively long duration, and the dense distribution of the power equipment in the switchgear makes the electromagnetic interference affect the entire switchgear. Therefore, the electromagnetic interference of the electromagnetic wave signals received by the same sensor changes little in a short period of time. The amplitude of the electromagnetic signal generated by the partial discharge pulse current is large, but due to the attenuation characteristics of the ultra-high frequency signal, the received amplitude of the farther sensor is small, resulting in a large difference in the influence of the partial discharge signal on different positions of the switchgear.

[0043] In order to reduce the influence of electromagnetic interference signals in the switchgear on partial discharge detection, it is necessary to accurately screen out the power frequency period where the partial discharge signal is located, and improve the measurement ability of weak partial discharge signals under strong interference. The specific process is as follows:

[0044] When a discharge occurs under the action of an applied voltage, the phase of the applied voltage is the phase of the partial discharge. Since the occurrence of partial discharge is closely related to the electric field strength in the insulating material, and the change of the electric field strength under alternating voltage is periodic, partial discharge events tend to concentrate near the peaks and valleys of the voltage waveform.

[0045] Based on the above analysis, by analyzing the differences between the phases corresponding to the maximum amplitudes of the electromagnetic wave signals in each sensor in each power frequency period and a preset first phase and a preset second phase respectively, and combining the maximum amplitudes, the interference coefficient of the electromagnetic wave signals in each sensor is determined to judge the interference of electromagnetic interference on partial discharge detection, so as to preliminarily limit the degree of electromagnetic interference on partial discharge in different power frequency periods. The specific determination process of the interference coefficient is as follows:

[0046] As a real-time method, in this embodiment, the interference coefficient F of the electromagnetic wave signal in sensor k k has the following expression:

[0047] In the formula, min k,t represents the minimum value of the differences between the phases corresponding to the maximum amplitudes of the electromagnetic wave signals in sensor k under the power frequency period t and the preset first phase and the preset second phase respectively; A k,t represents the maximum amplitude of the electromagnetic wave signal in sensor k under the power frequency period t; T represents the number of all power frequency periods; norm[] represents the normalization function; γ represents a preset constant greater than 1. In this embodiment, in order to reduce the weight of the electromagnetic wave signals whose amplitudes are close to the peaks and valleys of the power frequency voltage.

[0048] It should be noted that the values of the preset first phase and the preset second phase are set artificially. In this embodiment, the value of the preset first phase is 90°, and the value of the preset second phase is 270°. The reason for such values in this embodiment is that partial discharge is more likely to occur near the voltage peak, and the waveform of the alternating voltage is a sine waveform, and the phases at the peaks and valleys are 90° and 270°. Therefore, in this embodiment, the values of the preset first phase and the preset second phase are 90° and 270° respectively. In other embodiments, the implementer can also set them according to the specific situation by himself, and this embodiment does not make special restrictions.

[0049] It can be understood by analyzing the interference coefficient of the electromagnetic wave signal in each sensor that if the difference between the maximum amplitude of the current electromagnetic wave signal and the preset first phase or the preset second phase is smaller, it indicates that the maximum amplitude of the electromagnetic wave signal is closer to the peak or trough of the corresponding waveform of the sinusoidal alternating voltage within the power frequency cycle, indicating that the current electromagnetic wave signal is less affected by electromagnetic interference generated by circuit breakers, transformers, etc. Therefore, a smaller weight is assigned to the maximum amplitude of the current electromagnetic wave signal, and the finally obtained electromagnetic interference coefficient is smaller, indicating that the current electromagnetic wave signal is more likely to be an electromagnetic wave signal generated by partial discharge and is less likely to be affected by electromagnetic interference;

[0050] On the contrary, if the phase difference between the maximum amplitude of the electromagnetic wave signal and the peak or trough of the power frequency voltage waveform is large, this indicates that the current electromagnetic wave signal may be affected by electromagnetic interference from other sources, or is not a partial discharge signal synchronized with the voltage waveform. In this case, a larger weight will be assigned to the maximum amplitude of the current electromagnetic wave signal, resulting in a larger calculated interference coefficient, indicating that the current electromagnetic wave signal has a higher probability of being affected by electromagnetic interference. Therefore, the credibility that the current electromagnetic wave signal is generated by partial discharge is low.

[0051] So far, by analyzing the difference between the maximum amplitude of the electromagnetic wave signal and the peak or trough phase of the power frequency voltage, the interference coefficient of the electromagnetic wave signal is obtained, which is used to characterize the degree of electromagnetic interference suffered by the electromagnetic wave signal generated by the alternating voltage.

[0052] S202: Compare the differences in the maximum amplitudes between the electromagnetic wave signals of any two sensors under each power frequency cycle, and combine the interference coefficient to determine the amplitude deviation between the electromagnetic wave signals of any two sensors under each power frequency cycle.

[0053] Due to the dense distribution of power equipment in the switchgear cabinet, the influence distribution of the high-frequency components of the electromagnetic waves excited when the operating state of the switchgear cabinet changes tends to be consistent, which means that at different positions on the switchgear cabinet, the intensity change of the high-frequency components of the electromagnetic waves caused by switch operations, etc. is not significant. When the insulating material in the switchgear cabinet ages, partial discharge may occur, and the attenuation degree of the electromagnetic waves excited by the partial discharge to different distance sensors varies greatly, resulting in a large difference in the amplitudes of the partial discharge signals received by different sensors. Compared with the partial discharge signal, the amplitude of the high-frequency harmonic of the interference signal excited when the operating state of the switchgear cabinet changes is small.

[0054] Therefore, the greater the amplitude deviation between the electromagnetic wave signals of different sensors within the same power frequency cycle, the greater the probability of partial discharge in that power frequency cycle. Under each power frequency cycle, compare the differences in the maximum amplitudes between the electromagnetic wave signals of any two sensors, and combine the mean value of the interference coefficients of the electromagnetic wave signals in all sensors to determine the amplitude deviation between the electromagnetic wave signals of any two sensors under each power frequency cycle. Specifically:

[0055] As an implementation manner, in this embodiment, the amplitude deviation between the electromagnetic wave signals of sensor i and sensor j under the power frequency period t has the following expression: where L t represents the average interference coefficient of the electromagnetic wave signals among all sensors within the power frequency period t; represents the difference between the maximum amplitudes of the electromagnetic wave signals between sensor i and sensor j within the power frequency period t.

[0056] It should be noted that there are many methods to measure the difference between data. In this embodiment, the absolute value of the difference between the maximum amplitudes of the electromagnetic wave signals between sensor i and sensor j within the power frequency period t is used as the difference between the maximum amplitudes of the electromagnetic wave signals between sensor i and sensor j within the power frequency period t. In actual application processes, as other implementation manners, implementers can also use other methods to measure the difference between data, such as the square or ratio of the difference. Regarding the selection of the method to measure the difference between data, this embodiment does not make special restrictions.

[0057] From the amplitude deviations between the electromagnetic wave signals of any two sensors under each power frequency period, it can be obtained that: the average interference coefficient reflects the influence degree of the electromagnetic interference in the switch cabinet on the partial discharge detection of the sensor under the power frequency period t. If the average interference coefficient is larger, it indicates that the influence degree of the electromagnetic interference on the partial discharge detection is greater. And if the difference between the maximum amplitudes of the electromagnetic wave signals of different sensors within the power frequency period t is larger, it shows that the electromagnetic wave signals are more affected by the installation positions of the sensors, and the probability of partial discharge within the corresponding power frequency period is greater. Therefore, to prevent the influence of strong interference signals when screening partial discharge signals, at this time, the average interference coefficient is used as the calculation weight to increase the value of the amplitude deviation, so as to improve the detection ability for weak partial discharges.

[0058] So far, by analyzing the difference between the maximum amplitudes of the electromagnetic wave signals of different sensors under the same power frequency period and using the average interference coefficient as the weighting weight, the amplitude deviation is obtained, and the detection ability for weak partial discharges is improved.

[0059] S203: By analyzing the distance between any two sensors and combining the amplitude deviation, determine the comprehensive deviation of each power frequency period to screen out the target period from all power frequency periods, and compare the maximum amplitudes of the electromagnetic wave signals of all sensors within each target period to screen out the maximum partial discharge signal within each target period from the electromagnetic wave signals.

[0060] Furthermore, considering the influence of the positions of different sensors on the partial discharge detection, by analyzing the distance between any two sensors and combining the amplitude deviation, determine the comprehensive deviation of each power frequency period, specifically:

[0061] As an implementation manner, in this embodiment, the multiplication result of the amplitude deviation between the electromagnetic wave signals of any two sensors within each power frequency period and the distance between the corresponding sensors is calculated, and the accumulated value of the multiplication results between all sensors within each power frequency period is used as the comprehensive deviation of each power frequency period. Among them, the partial discharge signal will gradually attenuate during the propagation process. Therefore, if the distance between different sensors within the current power frequency period is farther and the amplitude deviation is larger, it indicates that the possibility of partial discharge within the current power frequency period is greater, and the obtained comprehensive deviation is larger.

[0062] Therefore, further, the mean value of the comprehensive deviations of all power frequency periods is calculated, denoted as the deviation mean value, and the power frequency periods corresponding to the comprehensive deviation greater than or equal to the deviation mean value are used as the target periods.

[0063] So far, by comprehensively analyzing the possibility of partial discharge phenomena within each power frequency period, the target periods with partial discharge phenomena have been screened out from all power frequency periods.

[0064] S204: Divide the frequency domain of the maximum partial discharge signal into multiple frequency intervals, and determine the partial discharge energy of each target period by analyzing the energy of the maximum partial discharge signal within each frequency interval and the dispersion degree of the maximum amplitude of the electromagnetic wave signals among all sensors within each target period.

[0065] The frequency of the electromagnetic wave excited by partial discharge is related to the pulse current generated by the discharge. The steeper the pulse current, the higher the frequency of the electromagnetic wave. And the steepness of the pulse current is related to the discharge gap. The smaller the discharge gap, the higher the steepness of the pulse current. Therefore, when the insulation fault of the switchgear in the large-scale distribution substation is more serious, the duration of a single partial discharge is longer, and the frequency of the excited electromagnetic wave is lower.

[0066] Considering that within the target period where the partial discharge phenomenon occurs, the larger the amplitude of the electromagnetic wave signal in the sensor, the closer it is to the current partial discharge position, the higher the signal-to-noise ratio of the electromagnetic wave signal, and the lower the degree of influence of electromagnetic interference, and it can more accurately reflect the severity of the current partial discharge.

[0067] Therefore, in this embodiment, the electromagnetic wave signal corresponding to the maximum value among the maximum amplitudes of all electromagnetic wave signals within each target period is used as the maximum partial discharge signal within each target period.

[0068] Furthermore, since the location of partial discharge has a great influence on measuring the severity of insulation faults, the frequency domain of the maximum partial discharge signal is divided into multiple frequency intervals. By analyzing the energy of the maximum partial discharge signal in each frequency interval and the degree of dispersion of the maximum amplitude of the electromagnetic wave signals among all sensors in each target period, the partial discharge energy of each target period is determined, specifically as follows:

[0069] In this embodiment, the frequencies of the maximum partial discharge signals in each target period in the frequency domain are evenly divided into N frequency intervals. Among them, the value of the number of frequency intervals N is set artificially. In this embodiment, the value of N is 4. In actual application processes, as other implementation manners, implementers can also set it by themselves according to specific situations, and this embodiment does not make special restrictions.

[0070] Furthermore, based on the energy of the maximum partial discharge signal in each frequency interval and the degree of dispersion of the maximum amplitude of the electromagnetic wave signals among all sensors in each target period, the partial discharge energy of each target period is determined, specifically:

[0071] The partial discharge energy H of target period z z has the following expression: CV z represents the degree of dispersion of the maximum amplitudes of all electromagnetic wave signals in target period z; w z,n represents the preset weight of the maximum partial discharge signal in frequency interval n in target period z. Among them, w z,1 + w z,2 + w z,3 + w z,4 = 1; E z,n represents the energy of the maximum partial discharge signal in the frequency interval in target period z; N z represents the number of all frequency intervals of the maximum partial discharge signal in target period z; ε represents a preset constant greater than 0, which is used to prevent the denominator from being 0. The value of ε is set artificially. In this embodiment, the value of ε is 0.01. On the premise of ensuring that the denominator is not 0 and does not overly affect the calculation result, implementers can also set it by themselves according to specific situations, and this embodiment does not make special restrictions.

[0072] It should be understood that the value of w z,n is set artificially. In this embodiment, the value of w z,1 is 0.4, the value of w z,2 is 0.3, the value of w z,3 is 0.2, and the value of w z,4 is 0.1. In other implementation manners, implementers can also set it by themselves according to specific situations, and this embodiment does not make special restrictions.

[0073] It should be noted that there are many methods to measure the dispersion degree of a set of data. In this embodiment, the coefficient of variation of the maximum amplitude of all electromagnetic wave signals within the target period z is used as the dispersion degree of the maximum amplitude of all electromagnetic wave signals within the target period z. In the actual application process, as other real-time methods, implementers can also use other methods to measure the dispersion degree of data, such as standard deviation or variance. Regarding the selection of methods for measuring the dispersion degree of data, this embodiment does not make special restrictions.

[0074] Among them, the calculation method of the coefficient of variation is a well-known technology, and its specific calculation process will not be elaborated here.

[0075] Analyzing the partial discharge energy of each target period shows that: since the electromagnetic waves generated by partial discharge will attenuate as the distance increases during propagation, therefore, if the dispersion degree of the maximum amplitude of electromagnetic wave signals among all sensors within the current target period is smaller, this means that the signals generated by partial discharge have experienced a similar attenuation process before reaching each sensor, so the signal amplitudes received by each sensor will be relatively close, that is, the consistency of the signal amplitudes is relatively high, indicating that the distance from the location of the current partial discharge to all sensors is relatively far, and a larger weight should be set to correct the energy of the electromagnetic wave signals to accurately reflect the severity of partial discharge in the sensors farther away from the location of partial discharge; on the contrary, if the dispersion degree of the maximum amplitude of electromagnetic wave signals among all sensors within the current target period is smaller, it means that the distance from the location of the current partial discharge to all sensors is relatively small, and a smaller weight should be set to correct the energy of the electromagnetic wave signals to accurately reflect the severity of partial discharge in the sensors farther away from the location of partial discharge.

[0076] So far, by analyzing the energy of the maximum partial discharge signal in each frequency interval and the dispersion degree of the maximum amplitude of electromagnetic wave signals among all sensors within each target period, the partial discharge energy of each target period has been obtained.

[0077] Preferably, the schematic diagram of the partial discharge energy extraction process provided in this embodiment is as Figure 2 shown.

[0078] Step S3: Based on the partial discharge energy of all target periods and the proportion of the number of all target periods in the total number of power frequency periods, determine the partial discharge index of the switchgear to be tested, and perform fault warning on the switchgear to be tested in a large-scale distribution substation.

[0079] The more power frequency periods with partial discharge signals, the higher the partial discharge frequency, and the more serious the insulation fault in the switchgear. At the same time, the greater the energy of the partial discharge signal within the power frequency period corresponding to the partial discharge, the more charge is released corresponding to the partial discharge, reflecting the more serious degree of a single partial discharge.

[0080] Therefore, based on the partial discharge energy of all target cycles and the proportion of the number of all target cycles in the total number of power frequency cycles, the partial discharge index of the switchgear under test is determined, specifically as follows:

[0081] As an implementation manner, in this embodiment, the sum of the partial discharge energies of all target cycles is calculated, and the product of the proportion of the number of all target cycles in the total number of power frequency cycles and the sum is used as the partial discharge index of the switchgear under test. The larger the partial discharge index, the greater the partial discharge frequency and the partial discharge energy, and the more serious the insulation fault of the switchgear. On the contrary, the smaller the partial discharge index, the smaller the partial discharge frequency and the partial discharge energy, and the less serious the insulation fault of the switchgear.

[0082] According to the method for obtaining the partial discharge index described in steps S1 - S3, obtain the partial discharge indexes of a preset number of switchgears without insulation faults, and record the maximum value among the partial discharge indexes as the insulation fault threshold. If the partial discharge index of the switchgear under test is greater than the absolute fault threshold, a fault warning is given to the large - scale distribution substation under test, and the upper computer transmits an alarm signal to the audible and visual alarm for insulation fault warning to remind the staff to carry out further maintenance. On the contrary, if the partial discharge index of the switchgear under test is less than or equal to the absolute fault threshold, no fault warning is given.

[0083] It should be noted that the value of the preset number is set manually. In this embodiment, the value of the preset number is 10000. In actual application, as other implementation manners, the implementer can also set it according to the specific situation by himself / herself, and this embodiment does not make special restrictions.

[0084] Based on the same inventive concept as the above method, the embodiment of the present application also provides a fault rapid warning system for a large - scale distribution substation, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above - mentioned fault rapid warning methods for a large - scale distribution substation.

[0085] It should be noted that: the above - mentioned sequence of the embodiments of the present application is only for description and does not represent the superiority or inferiority of the embodiments. And the above - mentioned specific embodiments of this specification have been described. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some implementation manners, multi - task processing and parallel processing are also possible or may be advantageous.

[0086] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments.

[0087] 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 principles of the present application shall be included in the protection scope of the present application.

Claims

1. A rapid fault warning method for a large-scale distribution station, characterized in that: The method comprises the following steps: Install multiple UHF sensors on the switch cabinet to be tested in a large-scale power distribution station, collect the electromagnetic wave signal and its maximum amplitude and phase in each UHF sensor in each power frequency cycle, and record the UHF sensor as sensor; Analyze the differences between the phase corresponding to the maximum amplitude of the electromagnetic wave signal in each sensor in each power frequency cycle and the preset first phase and the preset second phase, and determine the interference coefficient of the electromagnetic wave signal in each sensor in combination with the maximum amplitude; Under each power frequency cycle, the maximum amplitude difference between the electromagnetic wave signals of any two sensors is compared, and the amplitude deviation between the electromagnetic wave signals of any two sensors under each power frequency cycle is determined by combining the mean interference coefficient of the electromagnetic wave signals in all sensors; By analyzing the distance between any two sensors and combining the amplitude deviation, the comprehensive deviation of each power frequency cycle is determined to screen out a target cycle from all power frequency cycles, and the maximum amplitude of the electromagnetic wave signals in all sensors in each target cycle is compared to screen out the maximum partial discharge signal in each target cycle from the electromagnetic wave signal; The frequency domain of the maximum partial discharge signal is divided into multiple frequency intervals, and the partial discharge energy of each target period is determined by analyzing the energy of the maximum partial discharge signal in each frequency interval and the discrete degree of the maximum amplitude of the electromagnetic wave signal in all sensors in each target period; Based on the partial discharge energy of all target cycles and the proportion of the number of all target cycles in the total number of power frequency cycles, the partial discharge index of the switchgear to be tested is determined, and fault warning is given for the switchgear to be tested in large-scale distribution stations.

2. A large-scale distribution station fault rapid warning method as claimed in claim 1, characterized in that: The expression of the interference coefficient of the electromagnetic wave signal in each sensor is: In the formula, F k Indicates the interference coefficient of the electromagnetic wave signal in sensor k; min k,t A represents the minimum value of the difference between the phase corresponding to the maximum amplitude of the electromagnetic wave signal in the sensor k under the power frequency period t and the preset first phase and the preset second phase; k,t represents the maximum amplitude of the electromagnetic wave signal in sensor k under power frequency period t; T represents the number of all power frequency periods; norm[] represents the normalization function; γ represents a preset constant greater than 1.

3. A rapid fault warning method for a large-scale power distribution station as claimed in claim 1, characterized in that: The expression for the amplitude deviation between the electromagnetic wave signals of any two sensors under each power frequency cycle is: In the formula, It represents the amplitude deviation between the electromagnetic wave signals of sensor i and sensor j within the power frequency period t; L t It represents the mean value of the interference coefficient of the electromagnetic wave signals in all sensors within the power frequency period t; It represents the difference in the maximum amplitude between the electromagnetic wave signals in sensor i and sensor j within the power frequency period t.

4. A large-scale distribution station fault rapid warning method as claimed in claim 3, characterized in that: The method for determining the comprehensive deviation of each power frequency cycle is as follows: The multiplication result of the amplitude deviation between the electromagnetic wave signals of any two sensors in each power frequency cycle and the distance between the corresponding sensors is calculated, and the accumulated value of the multiplication results between all sensors in each power frequency cycle is used as the comprehensive deviation of each power frequency cycle.

5. A rapid fault warning method for a large-scale power distribution station as claimed in claim 1, characterized in that: The method for determining the target period is: The mean of the comprehensive deviations of all power frequency cycles is calculated and recorded as the deviation mean. The power frequency cycle corresponding to the comprehensive deviation being greater than or equal to the deviation mean is taken as the target cycle.

6. A rapid fault warning method for a large-scale power distribution station as claimed in claim 1, characterized in that: The maximum partial discharge signal in each target period is an electromagnetic wave signal corresponding to the maximum amplitude of all the maximum amplitudes of the electromagnetic wave signals in each target period when the maximum amplitude takes the maximum value.

7. A rapid fault warning method for a large-scale power distribution station as claimed in claim 1, characterized in that: The expression of the partial discharge energy of each target cycle is: H z represents the partial discharge energy of the target cycle z; CV z Indicates the discrete degree of the maximum amplitude of all electromagnetic wave signals within the target period z; w z,n represents the preset weight of the maximum partial discharge signal in the target period z within the frequency interval n, where w z,1 +w z,2 +w z,3 +w z,4 =1; E z,n N represents the energy of the maximum partial discharge signal in the frequency interval within the target period z; z represents the number of all frequency intervals of the maximum partial discharge signal within the target period z; ε represents a constant preset to be greater than 0.

8. A rapid fault warning method for a large-scale power distribution station as claimed in claim 1, characterized in that: The method for determining the partial discharge index of the switch cabinet to be tested is: The cumulative sum of the partial discharge energies of all target cycles is calculated, and the product of the proportion of the number of all target cycles in the total number of power frequency cycles and the cumulative sum is taken as the partial discharge index of the switchgear to be tested.

9. A rapid fault warning method for a large-scale power distribution station as claimed in claim 1, characterized in that: The method of providing a fault warning for a switch cabinet to be tested in a large-scale power distribution station includes: According to the method for obtaining the partial discharge index, the partial discharge indexes of a preset number of switch cabinets without insulation faults are obtained, and the maximum value of the partial discharge index is recorded as the absolute fault threshold. If the partial discharge index of the switch cabinet to be tested is greater than the absolute fault threshold, a fault warning is issued for the large-scale distribution station to be tested, otherwise, no fault warning is issued.

10. A rapid fault warning system for a large-scale power distribution station, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method for rapid fault warning of a large-scale distribution station as described in any one of claims 1 to 9 are implemented.

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