Multifunctional detection equipment and method for pole-mounted circuit breaker

Abstract

The invention relates to the technical field of pole-mounted circuit breaker fault detection, in particular to a multifunctional detection device and method for a pole-mounted circuit breaker, and the method comprises the steps: analyzing the correlation of current sequences of the same number between different phase currents and the correlation of trend vectors; a response synchronization factor is constructed by combining the change trend and the distribution condition of all the current data in the current sequence; and in any period of time, analyzing the difference between the amplitudes of each phase voltage at different frequencies in the frequency domain, determining the low-frequency stability in combination with the difference between the dispersion degree of all the temperature data and the maximum temperature data and the extreme distribution condition and dispersion degree of each phase voltage data, and detecting the pole-mounted circuit breaker in combination with the response synchronization factor. The invention aims to eliminate the interference of the constant threshold judgment condition error of the external environment and the natural fluctuation condition of the power grid load on the detection of the pole-mounted circuit breaker, and improves the detection accuracy of the pole-mounted circuit breaker.

Description

Technical Field

[0001] The present application relates to the technical field of pole-mounted circuit breaker fault detection, and in particular to a multifunctional detection device and method for a pole-mounted circuit breaker. Background Art

[0002] A circuit breaker is a switch device that can close, carry and interrupt the current under normal circuit conditions and close, carry and interrupt the current under abnormal circuit conditions within a specified time, while a pole-mounted circuit breaker is a circuit breaker installed and operated on a pole. With the rapid development of my country's economy and the continuous increase in power supply, the use of pole-mounted circuit breakers in the connection, segmentation and branch lines of the power grid is an important means to effectively ensure the safe operation of the power grid, improve the accuracy of fault detection and promote the development of the power industry; furthermore, the pole-mounted circuit breaker integrates primary and secondary equipment such as analog quantity acquisition, relay protection, and circuit breaker arc extinguishing structure, and is the core component of the modern intelligent distribution network.

[0003] The multiple closing logic of the pole-mounted circuit breaker is an important mechanism in its operation and protection strategy. It can test the faulty line multiple times within a certain period of time to avoid long-term power outages of the line due to temporary faults, which affects the power supply reliability of the power system. The false operation fault in the operation fault of the pole-mounted circuit breaker refers to the pole-mounted circuit breaker erroneously performing the opening and closing action without reaching the actual opening and closing condition, causing the multiple closing logic of the pole-mounted circuit breaker to fail to operate normally. When detecting the false operation fault of the pole-mounted circuit breaker, the prior art usually judges whether the circuit breaker opening and closing action can operate normally under the threshold conditions of constant current and constant voltage. However, the constant threshold does not take into account the interference of the external environment and the natural fluctuation of the power grid load. It is easy to cause the pole-mounted circuit breaker to erroneously trigger the tripping action when the line is in the normal operating range because the constant threshold judgment condition that does not take into account the interference of the external environment and the natural fluctuation of the power grid load is not considered, thereby reducing the accuracy of the detection of the pole-mounted circuit breaker. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a multifunctional detection device and method for a pole-mounted circuit breaker. The technical solutions adopted are as follows: In a first aspect, an embodiment of the present application provides a multifunctional detection method for a pole-mounted circuit breaker, the method comprising the following steps: Obtain the three-phase current data, three-phase voltage data and temperature data of the pole-mounted circuit breaker at all acquisition times within the preset time period; Divide the preset time into multiple time periods, analyze the change trend of each phase current data in any time period, determine all load change moments of each phase current in any time period, and form each current sequence of each phase current with each phase current data at each adjacent load change moment and all acquisition moments therebetween, and determine the trend vector of each phase current in any time period based on the change trend of all current data in each current sequence; In any period of time, all current sequences and all trend vectors of each phase current are numbered respectively, and the correlation of the current sequences of each phase current with the same number of all other phase currents, as well as the change trend of all current data in each current sequence of each phase current, is determined to determine the change correlation of each current sequence in each phase current in any period of time; Analyze the similarity of the trend vectors with the same number between each phase current and all other phase currents in any period, as well as the difference between the current data at each load change moment in each current sequence of each phase current and the average distribution of all current data, determine the response similarity of each current sequence in each phase current in any period, and determine the response synchronization factor of each phase current in any period in combination with the change correlation; In any period of time, the difference between the amplitudes of each phase voltage at different frequencies in the frequency domain is analyzed to determine the oscillation difference coefficient of each phase voltage in any period of time, and the low-frequency stability of each phase voltage in any period of time is determined by combining the difference between the discrete degree of all temperature data and the maximum temperature data, as well as the extreme distribution and discrete degree of each phase voltage data; The pole mounted circuit breaker is tested based on the response synchronization factor of all phase currents and the low frequency stability of all phase voltages in any period of time.

[0005] Preferably, the method for determining all load change moments of each phase current within any time period is: The current data of each phase at all collection moments in any time period are fitted to obtain the fitting curve of each phase current, the slope of each phase current fitting curve at each collection moment is calculated, and the standard deviation and mean of the slope at all collection moments are calculated, and the collection moment corresponding to the slope greater than the sum of the mean and three times the standard deviation is taken as the load change moment.

[0006] Preferably, the method for determining the trend vector of each phase current in any time period is: Each current sequence of each phase current in any period is taken as the input of the time series decomposition algorithm, and the trend strength of each current sequence is output. The trend strengths of all current sequences of each phase current in any period are combined to form the trend vector of each phase current in any period.

[0007] Preferably, the method for determining the correlation of changes in each current sequence in each phase current within any time period is: Calculate the cumulative sum of the correlations between the current sequences of the same number of each phase current and all other phase currents in any period of time, and record it as the correlation sum value of the current sequences of the same number of each phase current in any period of time; Calculate the information entropy of the slope of all current data at the corresponding acquisition time in each current sequence of each phase current in any period; The change correlation of each current sequence in each phase current in any time period is the ratio of the correlation sum value of each current sequence in each phase current in any time period to the information entropy.

[0008] Preferably, the method for determining the response similarity of each current sequence in each phase current within any time period is: Calculate the cumulative sum of similarities between trend vectors with the same number between each phase current and all other phase currents in any period, and record it as the relevant cumulative sum of trend vectors with the same number in any period; In each current sequence of each phase current in any period, the mean value of the current data at all acquisition moments except the load change moment is calculated and recorded as the current mean value, and the cumulative sum of the differences between the current data at all load change moments in each current sequence and the current mean value is taken as the difference sum value of each current sequence of each phase current in any period; The response similarity of each current sequence of each phase current in any period of time is the ratio of the relevant cumulative sum to the difference sum of each current sequence of each phase current in any period of time.

[0009] Preferably, the expression of the response synchronization factor of each phase current in any time period is: ; In the formula, represents the response synchronization factor of the p-th phase current in time period i; represents the correlation of the change of the jth current sequence in the pth phase current in the time period i; represents the response similarity of the jth current sequence in the pth phase current in time period i; Represents the number of all current sequences in the p-th phase current in time period i.

[0010] Preferably, the method for determining the oscillation difference coefficient of each phase voltage in any period of time is: The amplitude of each phase voltage data in any period at all frequencies within a preset frequency range in the frequency domain is recorded as the low-frequency amplitude; Oscillation difference coefficient of the p-th phase voltage in period i The expression is: ; In the formula, , They respectively represent the difference between the xth low-frequency amplitude in the p-th phase voltage in time period i and the corresponding amplitude at the maximum frequency of the p-th phase voltage data in the frequency domain, and the difference between the yth low-frequency amplitude and the corresponding amplitude at the maximum frequency of the p-th phase voltage data in the frequency domain; It represents the number of all low-frequency amplitudes of the p-th phase voltage in the frequency domain within time period i.

[0011] Preferably, the method for determining the low-frequency stability of each phase voltage in any period of time is: The inverse of the product of the range and the interquartile moment of the voltage data of each phase at all the sampling moments of the pole-mounted circuit breaker in any period of time is recorded as the concentration of the change of the voltage of each phase in any period of time; Low-frequency stability of the p-th phase voltage in time period i The expression is: ; In the formula, Represents the ratio of the standard deviation of the temperature data at all acquisition times within time period i to the maximum value; Indicates the concentration of the change of the p-th phase voltage in time period i; represents the oscillation difference coefficient of the p-th phase voltage in time period i, Indicates a preset constant greater than 0.

[0012] Preferably, the detecting of the pole-mounted circuit breaker includes: Calculate the sum of the response synchronization factors of all phase currents and the sum of the low-frequency stabilities of all phase voltages in any period of time, and use the normalized value of the product of the sum of the response synchronization factors and the sum of the low-frequency stabilities as the false operation fault coefficient of the pole-mounted circuit breaker in any period of time; The false operation fault coefficient of the pole-mounted circuit breaker in all time periods within the preset time length is used as the input of the threshold segmentation algorithm, and the segmentation threshold is output. If the false operation fault coefficient is greater than or equal to the segmentation threshold, the pole-mounted circuit breaker in the corresponding time period is faulty, otherwise, the pole-mounted circuit breaker in the corresponding time period is normal.

[0013] In a second aspect, an embodiment of the present application further provides a multifunctional detection device for a pole-mounted circuit breaker, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the multifunctional detection methods for a pole-mounted circuit breaker described above are implemented.

[0014] This application has at least the following beneficial effects: The present application constructs a response synchronization factor by analyzing the correlation of current sequences with the same number between different phase currents and the correlation of trend vectors, and combining the change trend and distribution of all current data in the current sequence, reflecting the synchronous recovery of each phase current at the pole-mounted circuit breaker port after the load changes, comprehensively considering the change correlation and response similarity of each phase current, and being able to more accurately reflect the synchronous recovery of each phase current response in the three-phase current caused by the normal change of the power grid load, which helps to eliminate the situation where normal charge fluctuations are misjudged as pole-mounted circuit breaker faults due to transient response, thereby improving the accuracy of pole-mounted circuit breaker detection; further, By analyzing the difference between the amplitudes of each phase voltage at different frequencies in the frequency domain, and combining the difference between the discreteness of all temperature data and the maximum temperature data, as well as the extreme distribution and discreteness of each phase voltage data, low-frequency stability is constructed, which can more accurately evaluate the stability of voltage, improve the accuracy of pole-mounted circuit breaker fault detection and the reliability of pole-mounted circuit breaker operation; further, by integrating the response synchronization factor and low-frequency stability, a false operation fault coefficient is constructed, which helps to distinguish between transient responses caused by load changes and real faults, thereby avoiding false operation faults caused by misjudgment and improving the accuracy of pole-mounted circuit breaker fault detection. This application eliminates the interference of false operation faults and improves the accuracy of pole-mounted circuit breaker detection by analyzing and taking into account the interference of the external environment and the natural fluctuations of the power grid load. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A flowchart of the steps of a multifunctional detection method for a pole-mounted circuit breaker provided in one embodiment of the present application; Figure 2 A schematic diagram of a malfunction fault coefficient extraction process provided for an embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of the multifunctional detection device and method for the pole-mounted circuit breaker proposed in the present application, its specific implementation, structure, features and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0019] The specific scheme of the multifunctional detection device and method for the pole-mounted circuit breaker provided by the present application is described in detail below with reference to the accompanying drawings.

[0020] See also Figure 1 , which shows a flowchart of the steps of a multifunctional detection method of a pole-mounted circuit breaker provided by an embodiment of the present application, the method comprising the following steps: Step S1: Acquire the three-phase current data, three-phase voltage data and temperature data of the pole-mounted circuit breaker at all acquisition moments within a preset time period.

[0021] A three-phase current transformer, a three-phase voltage transformer and a temperature transformer are installed at the pole-mounted circuit breaker port, and the three-phase current transformer, the three-phase voltage transformer and the temperature transformer are used to collect the three-phase current data, the three-phase voltage data and the temperature data at the pole-mounted circuit breaker port at all collection times within a preset time period, respectively. The collection frequency of the three-phase current data and the three-phase voltage data is set to F, and the collection frequency of the temperature data is set to f.

[0022] It should be noted that the preset time length, the collection frequency F of the three-phase current data and the three-phase voltage data, and the collection frequency f of the temperature data are all set manually. In this embodiment, the preset time length is 1h, the collection frequency F of the three-phase current data and the three-phase voltage data is 1KHz, and the collection frequency of the temperature data is 1Hz. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0023] Furthermore, in order to eliminate the impact of data dimension on subsequent analysis, the z-score standardization method is used to normalize all data. The z-score standardization method is a well-known technology in the field of data processing, and its specific principle process will not be repeated here.

[0024] Step S2: The current data of each phase at each adjacent load change moment and all the acquisition moments therebetween are combined into each current sequence of each phase current, and a trend vector is determined based on the change trend of all current data in each current sequence; the change correlation is determined by analyzing the correlation between each phase current and the current sequences with the same number of all other phase currents, as well as the change trend of all current data in each current sequence; the correlation between each phase current and the trend vectors with the same number of all other phase currents in any time period, as well as the distribution of all current data in each current sequence, is analyzed to determine the response similarity, and the response synchronization factor is determined in combination with the change correlation.

[0025] During the operation of the pole-mounted circuit breaker, the load of the power system may undergo normal changes with the peak and low peak power consumption of the power grid, while the three-phase current and voltage of the power line will change slowly with the normal fluctuations of the power system, and the three-phase current balance state will still be met during this period.

[0026] Specifically, under ideal conditions, the three-phase current will maintain a high degree of symmetry when the grid load fluctuates, that is, the change amplitude of each phase current is relatively balanced. In actual conditions, when the power system load changes normally with the peak and low peak of the grid, the current of each phase will produce highly synchronized fluctuations. That is, when the phase current of one phase produces a transient response change, the change degree of the phase current of the remaining two phases is relatively similar, and the changes in the current of each phase caused by normal load changes can quickly return to a stable state in a relatively short time.

[0027] At this time, if the fault threshold of the pole-mounted circuit breaker port is set to a constant threshold, it is easy to be disturbed by the transient response phenomenon caused by the rapid change of the power system load with the high and low peaks of the power grid, and mistakenly believe that the power system line is suffering from short circuit and other faults and execute tripping action, resulting in false operation faults and interfering with the reliable operation of the power system.

[0028] Therefore, in order to eliminate the situation where the normal response fluctuation of current caused by the change of power system load with the peak and low peak of the power grid is mistaken for the fault of the pole-mounted circuit breaker, the correlation of the current sequence with the same number between different phase currents and the correlation of the trend vector are analyzed, and the response synchronization factor of each phase current in any period is determined by combining the change trend and distribution of all current data in the current sequence, which is used to characterize the fluctuation of each phase current. Specifically: S201: Determine all load change moments of each phase current in any time period, and combine the current data of each phase at each adjacent load change moment and all acquisition moments therebetween to form each current sequence of each phase current, and determine the trend vector of each phase current in any time period based on the change trend of all current data in each current sequence.

[0029] First, in order to analyze the local changes of each phase current data, the preset time length is evenly divided into N time periods; It should be noted that the values ​​of N and K are both manually set. In this embodiment, the value of N is 30. Since the length of the preset duration in this embodiment is 1 hour, when the preset duration is divided into 30 time periods, the length of each time period is 2 minutes. The implementer can also set the division value N according to the specific situation. This embodiment does not impose any special restrictions.

[0030] Secondly, in order to more intuitively analyze the changing trend of the current data, the current data of each phase at all acquisition moments in any period are fitted to obtain the current fitting curve of each phase, and the slope at each acquisition moment on the current fitting curve of each phase is calculated, and the standard deviation and mean of the slope at all acquisition moments are calculated, and the acquisition moment corresponding to the slope greater than the sum of the mean and three times the standard deviation is used as the load change moment. It should be noted that there are many commonly used fitting methods. In this embodiment, the least squares fitting is used to fit the current data of each phase. The implementer can also use other fitting methods such as polynomial function fitting. This embodiment does not impose any special restrictions on the selection of the fitting method.

[0031] The horizontal axis of the current fitting curve represents the acquisition time, and the vertical axis represents the fitting value of the current data.

[0032] In addition, it should be understood that calculating the slope of each phase current fitting curve at each acquisition moment actually refers to the slope at the corresponding point on the current fitting curve at each acquisition moment. There are many methods for calculating the slope of each phase current fitting curve at each acquisition moment. The slope of the tangent at the point on the current fitting curve can be calculated, or the first-order derivative method can be used to calculate the slope at any point on the curve. In this embodiment, the first-order derivative method is used to calculate the slope at any point on the curve. The implementer can also choose a suitable method based on the specific situation. This embodiment does not impose any special restrictions.

[0033] Among them, the least square fitting and the first-order derivative are both well-known technologies, and their specific principles and steps are not repeated here.

[0034] Furthermore, in order to facilitate analysis, the current data of each phase at each adjacent load change moment and all the acquisition moments therebetween are combined to form each current sequence of each phase current; In particular, since the phase current data before the first load change moment within the preset time length and the phase current data after the last load change moment are greatly different in quantity from the phase current data between adjacent load change moments, the phase current data before the first load change moment within the preset time length and the phase current data after the last load change moment are not analyzed.

[0035] S202: In any time period, all current sequences and all trend vectors of each phase current are numbered respectively, and the correlation of the changes of each current sequence in each phase current in any time period is determined by analyzing the correlation of the current sequences with the same number between each phase current and all other phase currents, as well as the change trend of all current data in each current sequence of each phase current.

[0036] Firstly, in order to analyze the intensity of the local change trend of each phase current, each current sequence of each phase current in any period is used as the input of the time series decomposition algorithm, and the trend intensity of each current sequence is output. The trend intensity of all current sequences of each phase current in any period is combined to form the trend vector of each phase current in any period.

[0037] It should be noted that there are many commonly used time series decomposition algorithms. In this embodiment, the STL (Seasonal and Trend decomposition using Loess) time series decomposition algorithm is used to analyze the change trend of each current series. The implementer can also use the SEATS decomposition method to analyze the change trend of each current series. This embodiment does not impose any special restrictions on the selection of the time series decomposition algorithm.

[0038] Among them, the STL time series decomposition algorithm is a well-known technology, and the specific process of analyzing the data change trend will not be repeated here.

[0039] Furthermore, in order to analyze the local correlation of different phase currents and determine whether the current fluctuation is abnormal, all current sequences and trend vectors of each phase current are numbered in ascending time order in any period, and the cumulative sum of the correlations between each phase current and the current sequences with the same number of all other phase currents in any period is calculated, which is recorded as the correlation sum value of the current sequences with the same number of each phase current in any period; It should be noted that there are many methods for measuring the correlation between sequences. In this embodiment, the Pearson correlation coefficient of the current sequence with the same number between each phase current and all other phase currents is calculated to measure the correlation between the current sequences with the same number of different phase currents. The implementer may also use the Spearman correlation coefficient or the Kendall rank correlation coefficient to measure the correlation between different sequences. This embodiment does not impose any special restrictions on the selection of the method for measuring the correlation between sequences.

[0040] The calculation process of the Pearson correlation coefficient is a well-known technique, and the specific calculation steps are not described in detail.

[0041] Furthermore, in order to analyze the degree of chaos of the current data change, to determine whether the current fluctuation is abnormal, and thus to more accurately detect whether the pole-mounted circuit breaker has a fault, the information entropy of the slope of all current data corresponding to the collection time in each current sequence of each phase current in any period is calculated; The ratio of the correlation sum value of each current sequence of each phase current in any time period to the information entropy is taken as the change correlation of each current sequence in each phase current in any time period.

[0042] According to the correlation of the changes of each current sequence in each phase current in any period of time, it can be understood that the smoother the process of any phase current returning to a stable state, the weaker the chaos of the slope of the phase current data, that is, the smaller the information entropy; at the same time, when the normal change of the grid load causes the phase current of a phase to change, the higher the correlation of the changes in the other phase currents, the greater the cumulative result of the correlation between the p-th phase current and all the current sequences corresponding to the other phase currents, the greater the change correlation, indicating that the current fluctuation is normal, the more likely the change of the three-phase current is caused by the normal change of the grid load rather than the failure of the power line, and the easier it is for the currents of each phase to recover to a stable state synchronously after the change; On the contrary, the greater the degree of oscillation in the process of any phase current returning to a stable state, the more chaotic the slope of the phase current data of the phase is, that is, the greater the information entropy; at the same time, when the normal change of the grid load causes the phase current of a phase to change, the lower the correlation of the changes in the phase currents of the remaining phases, the smaller the cumulative result of the correlation between the p-th phase current and all current sequences corresponding to the remaining phase currents, and the smaller the change correlation, it means that the change in the three-phase current is more likely to be caused by a power line fault.

[0043] S203: Analyze the similarity of the trend vectors with the same number between each phase current and all other phase currents in any time period, and the difference between the current data at each load change moment in each current sequence of each phase current and the average distribution of all current data, determine the response similarity of each current sequence in each phase current in any time period, and determine the response synchronization factor of each phase current in any time period in combination with the change correlation.

[0044] Calculate the cumulative sum of similarities between trend vectors with the same number between each phase current and all other phase currents in any period, and record it as the relevant cumulative sum of trend vectors with the same number in any period; It should be noted that there are many methods for measuring the similarity between vectors. In this embodiment, the Jaccard similarity coefficient between the trend vectors with the same number between each phase current and all other currents is calculated to measure the similarity between the trend vectors with the same number between different phase currents. The implementer may also use other methods for measuring the similarity between vectors, such as cosine similarity. This embodiment does not impose any special restrictions on the selection of methods for measuring the similarity between vectors.

[0045] The calculation process of the Jaccard similarity coefficient is a well-known technique, and the specific calculation steps are not repeated here.

[0046] Furthermore, in each current sequence of each phase current in any period, the mean value of the current data at all acquisition moments except the load change moment is calculated and recorded as the current mean value, and the cumulative sum of the differences between the current data at all load change moments in each current sequence and the current mean value is taken as the difference sum value of each current sequence of each phase current in any period; It should be noted that there are many methods for measuring the difference between data. In this embodiment, the absolute value of the difference between the current data at all load change moments in each current sequence and the current mean is calculated to measure the difference between the current data at the load change moment and the current mean. The implementer may also use other methods for measuring the difference between data, such as ratio, square of difference, etc. This embodiment does not impose any special restrictions on the selection of the method for measuring the difference between data.

[0047] The ratio of the relevant cumulative sum to the difference sum of each current sequence of each phase current in any period of time is taken as the response similarity of each current sequence of each phase current in any period of time.

[0048] According to the response similarity of each current sequence of each phase current in any period of time, it can be understood that when the normal change of the power grid load causes the phase current of any phase at the pole-mounted circuit breaker port to change, the phase currents of the other phases will also change accordingly. Then, the greater the cumulative sum of the similarities between the trend vectors of the same number between each phase current and all other currents in any period of time, the more similar the process of each phase current recovering to a stable state after the transient interference caused by the normal change of the power system load is, and the greater the response similarity is; and the smaller the degree of mutation of each phase current, the easier it is to recover to a normal state after the mutation, that is, the smaller the difference and value, the greater the response similarity; On the contrary, when the normal change of the power grid load causes the phase current of any phase at the pole-mounted circuit breaker port to change, the currents of other phases will not change accordingly. In this case, the smaller the cumulative sum of the similarities between the trend vectors of the same number between each phase current and all other currents in any period of time, the greater the difference in the process of each phase current recovering to a stable state after the transient interference caused by the normal change of the power system load, and the smaller the response similarity; and the greater the degree of mutation of each phase current, the more difficult it is to recover to a normal state after the mutation, that is, the larger the difference and the value, the smaller the response similarity.

[0049] Furthermore, in order to determine whether there is a local fluctuation abnormality in the current, based on the response similarity and the change correlation, the response synchronization factor of each phase current in any time period is determined, specifically: The response synchronization factor of each phase current in time period i The expression is: ; In the formula, represents the correlation of the change of the jth current sequence in the pth phase current in the time period i; represents the response similarity of the jth current sequence in the pth phase current in time period i; Represents the number of all current sequences in the p-th phase current in time period i.

[0050] Furthermore, according to the response synchronization factor of each phase current in any time period, it can be understood that when the change of the three-phase current is more likely to be caused by the normal change of the grid load rather than the fault of the power line, the easier it is for each phase current to recover to a stable state synchronously after the change, that is, the greater the change correlation and the greater the response similarity, the greater the response synchronization factor; conversely, when the change of the three-phase current is more likely to be caused by the fault of the power line, the harder it is for each phase current to recover to a stable state synchronously after the change, that is, the smaller the change correlation and the smaller the response similarity, the smaller the response synchronization factor.

[0051] Step S3: In any time period, the difference between the amplitudes of each phase voltage at different frequencies in the frequency domain is analyzed to determine the oscillation difference coefficient of each phase voltage in any time period, and the low-frequency stability of each phase voltage in any time period is determined by combining the difference between the discreteness of all temperature data and the maximum temperature data, as well as the extreme distribution and discreteness of each phase voltage data.

[0052] Grid interconnection is one of the important foundations of smart grid. Grid interconnection can not only optimize the allocation of power resources, but also enhance the reliability of the overall grid operation. Grid interconnection will also cause changes in the load of the power system. At this time, the response recovery synchronization of the three-phase current at the pole-mounted circuit breaker port to the current of each phase is not enough to fully and accurately evaluate the normal changes of the power system. When the load of the power system changes normally due to grid interconnection, the low-frequency oscillation phenomenon of the voltage fluctuations of each phase caused can more accurately reflect the voltage stability of the power system, but the external ambient temperature may cause the voltage data collected at the pole-mounted circuit breaker port to be seriously interfered by noise, affecting the accuracy of the voltage low-frequency oscillation analysis.

[0053] Specifically, in the process of power grid interconnection, cross-regional power dispatching is usually involved, which causes load changes in the power system. The negative damping factor in the power system may cause low-frequency oscillation of the three-phase voltage. The continuous accumulation of this phenomenon will weaken the operational stability of the power system, thereby affecting the operation of the power system. When the frequency component energy amplitude oscillation phenomenon of the voltage spectrum of each phase in the three-phase voltage is within the preset frequency range, and the high temperature abnormality at the pole-mounted circuit breaker port is more vague, it means that the current pole-mounted circuit breaker is less affected by external high temperature interference, the higher the accuracy of the voltage data obtained, the more vague the low-frequency oscillation of the voltage of the power system, and the stronger the stability of the power system.

[0054] Based on the above analysis, the amplitude of each phase voltage data at all frequencies within a preset frequency range in the frequency domain in any period is recorded as the low-frequency amplitude; Furthermore, by analyzing the difference between the amplitudes of each phase voltage at different frequencies in the frequency domain, the oscillation difference coefficient of each phase voltage in any period is determined, specifically: Oscillation difference coefficient of the p-th phase voltage in period i The expression is: ; In the formula, , They respectively represent the difference between the xth low-frequency amplitude in the p-th phase voltage in time period i and the corresponding amplitude at the maximum frequency of the p-th phase voltage data in the frequency domain, and the difference between the yth low-frequency amplitude and the corresponding amplitude at the maximum frequency of the p-th phase voltage data in the frequency domain; It represents the number of all low-frequency amplitudes of the p-th phase voltage in the frequency domain within time period i.

[0055] It should be noted that there are many methods for measuring the differences between data. In this embodiment, the absolute values ​​of the differences between the x-th low-frequency amplitude and the y-th low-frequency amplitude in the p-th phase voltage and the corresponding amplitude of the p-th phase voltage data at the maximum frequency in the frequency domain are calculated respectively to measure the differences between each low-frequency amplitude and the corresponding amplitude of the corresponding phase voltage data at the maximum frequency in the frequency domain. The implementer may also use other methods for measuring the differences between data, such as ratio and square of difference. This embodiment does not impose any special restrictions on the selection of methods for measuring the differences between data.

[0056] According to the oscillation difference coefficient of each phase voltage in any period of time, it can be understood that when the power system load changes normally due to the interconnection of the power grid, the higher the low-frequency oscillation stability of each phase voltage in the three-phase voltage, the smaller the energy amplitude fluctuation of the low-frequency frequency component in each phase voltage in the three-phase voltage, that is, the difference between the x-th low-frequency amplitude and the y-th low-frequency amplitude in the p-th phase voltage and the corresponding amplitude at the maximum frequency in the frequency domain of the p-th phase voltage data is, that is, The smaller it is, the smaller the oscillation difference coefficient is; on the contrary, when the power grid interconnection causes abnormal changes in the load of the power system, the lower the low-frequency oscillation stability of each phase voltage in the three-phase voltage, the greater the fluctuation of the energy amplitude of the low-frequency frequency component in each phase voltage in the three-phase voltage, that is, the greater the difference between the x-th low-frequency amplitude and the y-th low-frequency amplitude in the p-th phase voltage and the corresponding amplitude at the maximum frequency in the frequency domain of the p-th phase voltage data. The larger it is, the greater the oscillation difference coefficient is.

[0057] Furthermore, the inverse of the product of the range and the interquartile range of the voltage data of each phase at all the acquisition moments of the pole-mounted circuit breaker in any period is taken and recorded as the concentration of the change of the voltage of each phase in any period; The calculation process of the interquartile range is a well-known technique, and the specific calculation steps will not be repeated here.

[0058] Furthermore, based on the oscillation difference coefficient of each phase voltage in any period, combined with the difference between the discrete degree of all temperature data and the maximum temperature data, as well as the extreme distribution and discrete degree of each phase voltage data, the low-frequency stability of each phase voltage in any period is determined, specifically: Low-frequency stability of the p-th phase voltage in time period i The expression is: ; In the formula, It represents the ratio of the standard deviation of the temperature data at all acquisition times within time period i to the maximum value; Indicates the concentration of the change of the p-th phase voltage in time period i; represents the oscillation difference coefficient of the p-th phase voltage in time period i; Indicates a constant greater than 0 to prevent the denominator from being 0. The value of is set manually. The value of is 0.01. The implementer can also set it according to the specific situation, provided that the denominator is not 0 and the calculation result is not excessively affected. This embodiment does not impose any special restrictions.

[0059] According to the low-frequency stability of each phase voltage in any period of time, it can be understood that when the temperature fluctuation of the pole-mounted circuit breaker in a certain time interval is milder, the maximum temperature is smaller, indicating that the abnormal temperature condition of the pole-mounted circuit breaker in the said certain time interval is more vague, and the pole-mounted circuit breaker is disturbed by the external temperature, which makes the possibility of the collected three-phase voltage data accurate, that is, the ratio of the standard deviation to the maximum value is larger; when the change of the three-phase voltage is more likely to be caused by the normal change of the load of the power system caused by the interconnection of the power grid rather than the power line failure, the stability of each phase voltage in the three-phase voltage is stronger, that is, the low-frequency difference coefficient is smaller; the smaller the change of each phase voltage data in the three-phase voltage and the more concentrated the change range, that is, the smaller the difference between the extreme values ​​of each phase voltage in the three-phase voltage and the interquartile range of the phase voltage data sequence, the greater the change concentration; that is, the larger the ratio of the standard deviation of the changing temperature data to the maximum value, the smaller the low-frequency difference coefficient, the greater the change concentration, and the greater the low-frequency stability; conversely, the smaller the ratio of the standard deviation of the changing temperature data to the maximum value, the larger the low-frequency difference coefficient, the smaller the change concentration, and the smaller the low-frequency stability.

[0060] Step S4: Based on the response synchronization factors of all phase currents and the low-frequency stability of all phase voltages in any time period, the pole-mounted circuit breaker is detected.

[0061] When the pole-mounted circuit breaker is detecting the power line, the stronger the synchronous recovery of the current response of each phase, the milder the high temperature anomaly of the external environment, and the stronger the stability of the voltage of each phase, it means that the current and voltage changes in the power line are more likely to be caused by normal changes in the grid load or grid interconnection rather than power line failure. At this time, if the pole-mounted circuit breaker performs a tripping action, it means that the possibility of a false operation of the pole-mounted circuit breaker is higher.

[0062] Therefore, the false operation fault coefficient of the pole-mounted circuit breaker can be determined by the response synchronization factor of each phase current in the three-phase current and the voltage stability of each phase in the three-phase voltage. Specifically: Calculate the sum of the response synchronization factors of all phase currents and the sum of the low-frequency stabilities of all phase voltages in any period of time, and use the normalized value of the product of the sum of the response synchronization factors and the sum of the low-frequency stabilities as the false operation fault coefficient of the pole-mounted circuit breaker in any period of time; When the three-phase current and three-phase voltage fluctuations caused by changes in the load of the power system are more likely to be caused by normal changes in the grid load or grid interconnection rather than power line failures, the possibility that the pole-mounted circuit breaker performs a tripping action as a false operation fault is higher, that is, the false operation fault coefficient is larger; the stronger the correlation between the changes in the three-phase currents at the pole-mounted circuit breaker port, the stronger the similarity of the responses of the phase currents, that is, the larger the cumulative result of the response synchronization factors of all phase currents in the three-phase current; at the same time, the stronger the concentration of the voltage changes in each phase of the three-phase voltage, the stronger the low-frequency stability, and the less interference from external high temperature anomalies, that is, the larger the cumulative result of the low-frequency stability of all phase voltages in the three-phase voltage.

[0063] Preferably, the schematic diagram of the malfunction fault coefficient extraction process provided in this embodiment is as follows: Figure 2 shown.

[0064] Furthermore, the false operation fault coefficient of the pole-mounted circuit breaker in all time periods within the preset time length is used as the input of the threshold segmentation algorithm, and the segmentation threshold is output. If the false operation fault coefficient is greater than or equal to the segmentation threshold, the pole-mounted circuit breaker in the corresponding time period is faulty, otherwise, the pole-mounted circuit breaker in the corresponding time period is normal.

[0065] It should be noted that there are many commonly used threshold segmentation algorithms. In this embodiment, the Otsu threshold segmentation algorithm is used to obtain the segmentation threshold. The implementer may also use other threshold segmentation algorithms to classify the malfunction coefficient. This embodiment does not impose any special restrictions on the selection of the threshold segmentation algorithm.

[0066] Based on the same inventive concept as the above method, an embodiment of the present application also provides a multifunctional detection device for a pole-mounted circuit breaker, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the multifunctional detection methods for the pole-mounted circuit breaker are implemented.

[0067] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0068] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0069] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A multifunctional detection method for a pole-mounted circuit breaker, characterized in that: The method comprises the following steps: Obtain the three-phase current data, three-phase voltage data and temperature data of the pole-mounted circuit breaker at all acquisition times within the preset time period; Divide the preset time into multiple time periods, analyze the change trend of each phase current data in any time period, determine all load change moments of each phase current in any time period, and form each current sequence of each phase current with each phase current data at each adjacent load change moment and all acquisition moments therebetween, and determine the trend vector of each phase current in any time period based on the change trend of all current data in each current sequence; In any period of time, all current sequences and all trend vectors of each phase current are numbered respectively, and the correlation of the current sequences of each phase current with the same number of all other phase currents, as well as the change trend of all current data in each current sequence of each phase current, is determined to determine the change correlation of each current sequence in each phase current in any period of time; Analyze the similarity of the trend vectors with the same number between each phase current and all other phase currents in any period, as well as the difference between the current data at each load change moment in each current sequence of each phase current and the average distribution of all current data, determine the response similarity of each current sequence in each phase current in any period, and determine the response synchronization factor of each phase current in any period in combination with the change correlation; In any period of time, the difference between the amplitudes of each phase voltage at different frequencies in the frequency domain is analyzed to determine the oscillation difference coefficient of each phase voltage in any period of time, and the low-frequency stability of each phase voltage in any period of time is determined by combining the difference between the discrete degree of all temperature data and the maximum temperature data, as well as the extreme distribution and discrete degree of each phase voltage data; The pole mounted circuit breaker is tested based on the response synchronization factor of all phase currents and the low frequency stability of all phase voltages in any period of time.

2. The multifunctional detection method for a pole mounted circuit breaker according to claim 1, characterized in that: The method for determining all load change moments of each phase current within any period is as follows: The current data of each phase at all collection moments in any time period are fitted to obtain the fitting curve of each phase current, the slope of each phase current fitting curve at each collection moment is calculated, and the standard deviation and mean of the slope at all collection moments are calculated, and the collection moment corresponding to the slope greater than the sum of the mean and three times the standard deviation is taken as the load change moment.

3. The multifunctional detection method for a pole mounted circuit breaker according to claim 1, characterized in that: The method for determining the trend vector of each phase current in any period is as follows: Each current sequence of each phase current in any period is taken as the input of the time series decomposition algorithm, and the trend strength of each current sequence is output. The trend strengths of all current sequences of each phase current in any period are combined to form the trend vector of each phase current in any period.

4. The multifunctional detection method for a pole mounted circuit breaker according to claim 2, characterized in that: The method for determining the correlation of changes in each current sequence in each phase current within any period of time is: Calculate the cumulative sum of the correlations between the current sequences of the same number of each phase current and all other phase currents in any period of time, and record it as the correlation sum value of the current sequences of the same number of each phase current in any period of time; Calculate the information entropy of the slope of all current data at the corresponding acquisition time in each current sequence of each phase current in any period; The change correlation of each current sequence in each phase current in any time period is the ratio of the correlation sum value of each current sequence in each phase current in any time period to the information entropy.

5. The multifunctional detection method for a pole mounted circuit breaker according to claim 1, characterized in that: The method for determining the response similarity of each current sequence in each phase current within any period is as follows: Calculate the cumulative sum of similarities between trend vectors with the same number between each phase current and all other phase currents in any period, and record it as the relevant cumulative sum of trend vectors with the same number in any period; In each current sequence of each phase current in any period, the mean value of the current data at all acquisition moments except the load change moment is calculated and recorded as the current mean value, and the cumulative sum of the differences between the current data at all load change moments in each current sequence and the current mean value is taken as the difference sum value of each current sequence of each phase current in any period; The response similarity of each current sequence of each phase current in any period of time is the ratio of the relevant cumulative sum to the difference sum of each current sequence of each phase current in any period of time.

6. The multifunctional detection method for a pole mounted circuit breaker according to claim 1, characterized in that: The expression of the response synchronization factor of each phase current in any period is: ; In the formula, represents the response synchronization factor of the p-th phase current in time period i; represents the correlation of the change of the jth current sequence in the pth phase current in the time period i; represents the response similarity of the jth current sequence in the pth phase current in time period i; Represents the number of all current sequences in the p-th phase current in time period i.

7. The multifunctional detection method for a pole mounted circuit breaker according to claim 1, characterized in that: The method for determining the oscillation difference coefficient of each phase voltage in any period is as follows: The amplitude of each phase voltage data in any period at all frequencies within a preset frequency range in the frequency domain is recorded as the low-frequency amplitude; Oscillation difference coefficient of the p-th phase voltage in period i The expression is: ; In the formula, , They respectively represent the difference between the xth low-frequency amplitude in the p-th phase voltage in time period i and the corresponding amplitude at the maximum frequency of the p-th phase voltage data in the frequency domain, and the difference between the yth low-frequency amplitude and the corresponding amplitude at the maximum frequency of the p-th phase voltage data in the frequency domain; It represents the number of all low-frequency amplitudes of the p-th phase voltage in the frequency domain within time period i.

8. The multifunctional detection method for a pole mounted circuit breaker according to claim 1, characterized in that: The method for determining the low-frequency stability of each phase voltage in any period is as follows: The inverse of the product of the range and the interquartile moment of the voltage data of each phase at all the sampling moments of the pole-mounted circuit breaker in any period of time is recorded as the concentration of the change of the voltage of each phase in any period of time; Low-frequency stability of the p-th phase voltage in time period i The expression is: ; In the formula, Represents the ratio of the standard deviation of the temperature data at all acquisition times within time period i to the maximum value; Indicates the concentration of the change of the p-th phase voltage in time period i; represents the oscillation difference coefficient of the p-th phase voltage in time period i, Indicates a preset constant greater than 0.

9. The multifunctional detection method for a pole mounted circuit breaker according to claim 1, characterized in that: The detecting of the pole mounted circuit breaker comprises: Calculate the sum of the response synchronization factors of all phase currents and the sum of the low-frequency stabilities of all phase voltages in any period of time, and use the normalized value of the product of the sum of the response synchronization factors and the sum of the low-frequency stabilities as the false operation fault coefficient of the pole-mounted circuit breaker in any period of time; The false operation fault coefficient of the pole-mounted circuit breaker in all time periods within the preset time length is used as the input of the threshold segmentation algorithm, and the segmentation threshold is output. If the false operation fault coefficient is greater than or equal to the segmentation threshold, the pole-mounted circuit breaker in the corresponding time period is faulty, otherwise, the pole-mounted circuit breaker in the corresponding time period is normal.

10. A multifunctional detection device for a pole-mounted circuit breaker, 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 multifunctional detection method for a pole-mounted circuit breaker according to any one of claims 1 to 9 are implemented.

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