Multifunctional Detection Equipment and Method for Pole-Mounted Circuit Breakers

Abstract

This application relates to the technical field of fault detection of pole-mounted circuit breakers, specifically to a multi-functional detection device and method for pole-mounted circuit breakers. The method includes: constructing 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; within any time period, analyzing the differences in amplitudes at different frequencies of each-phase voltage in the frequency domain, and combining the difference between the dispersion degree of all temperature data and the maximum temperature data, as well as the extreme distribution and dispersion degree of each-phase voltage data, to determine the low-frequency stability, and combining the response synchronization factor to detect the pole-mounted circuit breaker. The purpose of this application is to eliminate the interference of the constant threshold judgment condition error of the natural fluctuation of the external environment and the power grid load on the detection of the pole-mounted circuit breaker, and improve the accuracy of the detection of the pole-mounted circuit breaker.

Description

Technical Field

[0001] This application relates to the technical field of fault detection of pole-mounted circuit breakers, and specifically relates to a multi-functional detection device and method for pole-mounted circuit breakers. Background Art

[0002] A circuit breaker refers to a switching device that can close, carry, and interrupt the current under normal circuit conditions and can close, carry, and interrupt the current under abnormal circuit conditions within a specified time. A pole-mounted circuit breaker refers to a circuit breaker installed and operated on an electric pole. With the rapid economic development of our country and the continuous increase in power supply, using pole-mounted circuit breakers in the connection, sectioning, 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 modern intelligent distribution networks.

[0003] The multiple closing logic of the pole-mounted circuit breaker is an important mechanism in its operation and protection strategy, which can test the faulty line multiple times within a certain period of time to avoid long-term power outage of the line caused by temporary faults and affect the power supply reliability of the power system. The misoperation fault in the operation fault of the pole-mounted circuit breaker refers to the situation where the pole-mounted circuit breaker wrongly performs the closing and opening operations without reaching the actual closing and opening conditions, resulting in the inability of the multiple closing logic of the pole-mounted circuit breaker to operate normally. When the prior art detects the misoperation fault of the pole-mounted circuit breaker, it usually judges whether the closing and opening operations of the circuit breaker can operate normally under the threshold conditions of constant current and constant voltage. However, the constant threshold does not consider the interference of the external environment and the natural fluctuation of the power grid load, which easily causes the pole-mounted circuit breaker to wrongly trigger the tripping operation due to the constant threshold judgment condition that does not consider the interference of the external environment and the natural fluctuation of the power grid load when the line is in the normal operation range, 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 multi-functional detection device and method for pole-mounted circuit breakers, and the specific technical solutions adopted are as follows:

[0005] In the first aspect, an embodiment of this application provides a multi-functional detection method for a pole-mounted circuit breaker, and the method includes the following steps:

[0006] Obtain 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 duration;

[0007] Divide the preset duration into multiple time periods, analyze the change trends of the phase current data within any time period, determine all the load change moments of the phase currents within any time period, and form each current sequence of the phase currents with each adjacent load change moment and the phase current data at all the acquisition moments therebetween. Based on the change trends of all the current data in each current sequence, determine the trend vectors of the phase currents within any time period;

[0008] Within any time period, number all the current sequences and all the trend vectors of the phase currents respectively. By analyzing the correlation between the current sequences with the same number between each phase current and all the other phase currents, as well as the change trends of all the current data in each current sequence of the phase currents, determine the change correlation of each current sequence of the phase currents within any time period;

[0009] Analyze the similarity between the trend vectors with the same number between each phase current and all the other phase currents within any time period, as well as the difference between the current data at each load change moment in each current sequence of the phase currents and the average distribution of all the current data, determine the response similarity of each current sequence of the phase currents within any time period, and combine the change correlation to determine the response synchronization factor of the phase currents within any time period;

[0010] Within any time period, analyze the difference between the amplitudes at different frequencies of each phase voltage in the frequency domain, determine the oscillation difference coefficient of each phase voltage within any time period, and combine the difference between the dispersion degree of all the temperature data and the maximum temperature data, as well as the extreme distribution and dispersion degree of each phase voltage data, determine the low-frequency stability of each phase voltage within any time period;

[0011] Based on the response synchronization factor of all the phase currents and the low-frequency stability of all the phase voltages within any time period, detect the pole-mounted circuit breaker.

[0012] Preferably, the method for determining all the load change moments of the phase currents within any time period is as follows:

[0013] Fit the phase current data at all the acquisition moments within any time period to obtain the phase current fitting curves, calculate the slope at each acquisition moment on each phase current fitting curve, and calculate the standard deviation and mean value of the slopes at all the acquisition moments. Take the acquisition moment corresponding to the slope greater than the sum of the mean value and three times the standard deviation as the load change moment.

[0014] Preferably, the method for determining the trend vectors of the phase currents within any time period is as follows:

[0015] Take each current sequence of the phase currents within any time period as the input of the time series decomposition algorithm, output the trend intensity of each current sequence, and form the trend vectors of the phase currents within any time period with the trend intensities of all the current sequences of the phase currents within any time period.

[0016] Preferably, the method for determining the change correlation of each current sequence in each phase current within any time period is as follows:

[0017] Calculate the cumulative sum of the correlations of the current sequences with the same number between each phase current and all the other phase currents within any time period, and denote it as the correlation sum value of the current sequences with the same number in each phase current within any time period;

[0018] Calculate the information entropy of the slopes at the corresponding acquisition moments of all current data in each current sequence of each phase current within any time period;

[0019] The change correlation of each current sequence in each phase current within any time period is the ratio of the correlation sum value of each current sequence of each phase current within any time period to the information entropy.

[0020] Preferably, the method for determining the response similarity of each current sequence in each phase current within any time period is as follows:

[0021] Calculate the cumulative sum of the similarities between the trend vectors with the same number between each phase current and all the other phase currents within any time period, and denote it as the cumulative correlation sum of the trend vectors with the same number within any time period;

[0022] In each current sequence of each phase current within any time period, calculate the mean value of the current data at all acquisition moments except the load change moments, and denote it as the current mean value, and take the cumulative sum of the differences between the current data at all load change moments in each current sequence and the current mean value as the difference sum value of each current sequence of each phase current within any time period;

[0023] The response similarity of each current sequence of each phase current within any time period is the ratio of the cumulative correlation sum of each current sequence of each phase current within any time period to the difference sum value.

[0024] Preferably, the expression of the response synchronization factor of each phase current within any time period is: ; where represents the response synchronization factor of the p-th phase current in the i-th time period; represents the change correlation of the j-th current sequence in the p-th phase current in the i-th time period; represents the response similarity of the j-th current sequence in the p-th phase current in the i-th time period; represents the number of all current sequences in the p-th phase current in the i-th time period.

[0025] Preferably, the method for determining the oscillation difference coefficient of each phase voltage within any time period is as follows:

[0026] Denote the amplitudes of each phase voltage data at all frequencies within the preset frequency range in the frequency domain within any time period as the low-frequency amplitudes;

[0027] Oscillation difference coefficient of the p-phase voltage within the time period i The expression is as follows: ; In the formula, 、 respectively represent the difference between the x-th low-frequency amplitude in the p-phase voltage within the time period i and the amplitude corresponding to the maximum frequency in the frequency domain of the p-phase voltage data, and the difference between the y-th low-frequency amplitude and the amplitude corresponding to the maximum frequency in the frequency domain of the p-phase voltage data; represents the number of all low-frequency amplitudes of the p-phase voltage within the time period i in the frequency domain.

[0028] Preferably, the method for determining the low-frequency stability of each phase voltage within any time period is as follows:

[0029] Take the reciprocal of the product of the range and the interquartile range of the phase voltage data at all acquisition moments of the pole-mounted circuit breaker within any time period, and denote it as the change concentration of each phase voltage within any time period;

[0030] Low-frequency stability of the p-phase voltage within the time period i The expression is as follows: ; In the formula, represents the ratio of the standard deviation to the maximum value of the temperature data at all acquisition moments within the time period i; represents the change concentration of the p-phase voltage within the time period i; represents the oscillation difference coefficient of the p-phase voltage within the time period i, represents a preset constant greater than 0.

[0031] Preferably, the detection of the pole-mounted circuit breaker includes:

[0032] Calculate the sum value of the response synchronization factors of all phase currents and the sum value of the low-frequency stabilities of all phase voltages within any time period, and use the normalized value of the product of the sum value of the response synchronization factors and the sum value of the low-frequency stabilities as the misoperation fault coefficient of the pole-mounted circuit breaker within any time period;

[0033] Use the misoperation fault coefficients of the pole-mounted circuit breaker within all time periods within a preset duration as the input of the threshold segmentation algorithm, and output the segmentation threshold. If the misoperation fault coefficient is greater than or equal to the segmentation threshold, the pole-mounted circuit breaker fails within the corresponding time period, otherwise, the pole-mounted circuit breaker is normal within the corresponding time period.

[0034] In a second aspect, the embodiments of the present application further provide a multifunctional detection device for a pole-mounted circuit breaker, 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 the multifunctional detection method for the pole-mounted circuit breaker described in any one of the above.

[0035] The present application has at least the following beneficial effects:

[0036] By analyzing the correlation of current sequences with the same number among different phase currents and the correlation of trend vectors, and combining the change trends and distribution of all current data in the current sequence, the present application constructs a response synchronization factor, which reflects the synchronous recovery of each phase current at the pole-mounted circuit breaker port after the load changes. Considering the change correlation and response similarity of each phase current comprehensively, it can more accurately reflect the synchronous recovery of each phase current in the three-phase current caused by the normal change of the grid load, helps to exclude the situation of misjudging normal charge fluctuations as pole-mounted circuit breaker faults due to transient responses, and improves the accuracy of detecting pole-mounted circuit breakers; further, by analyzing the differences in amplitudes at different frequencies in the frequency domain of each phase voltage, and combining the difference between the dispersion degree of all temperature data and the maximum temperature data, as well as the extreme distribution and dispersion degree of each phase voltage data, a low-frequency stability is constructed, which can more accurately evaluate the voltage stability, improves the accuracy of detecting pole-mounted circuit breaker faults and the reliability of the operation of pole-mounted circuit breakers; further, by combining the response synchronization factor and low-frequency stability, a misoperation fault coefficient is constructed, which helps to distinguish transient responses caused by load changes from real faults, thus avoiding misoperation faults caused by misjudgment and improving the accuracy of detecting pole-mounted circuit breaker faults. By analyzing and considering the interference of the external environment and the natural fluctuations of the grid load, the present application excludes the interference of misoperation faults and improves the accuracy of detecting pole-mounted circuit breakers. Description of the Drawings

[0037] 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 drawings in the following description 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.

[0038] Figure 1 It is a flowchart of the steps of a multi-functional detection method for a pole-mounted circuit breaker provided by an embodiment of the present application;

[0039] Figure 2 It is a schematic diagram of the misoperation fault coefficient extraction process provided by an embodiment of the present application. Detailed Embodiments

[0040] In order to further elaborate on the technical means and effects adopted by this application to achieve the intended invention purpose, the following specifically describes, in conjunction with the accompanying drawings and preferred embodiments, the specific implementation manners, structures, features, and effects of the multi-functional detection device and method for pole-mounted circuit breakers according to this application. 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.

[0041] 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.

[0042] The following specifically describes the specific solutions of the multi-functional detection device and method for pole-mounted circuit breakers provided by this application in conjunction with the accompanying drawings.

[0043] Please refer to Figure 1 , which shows the step flow chart of the multi-functional detection method for pole-mounted circuit breakers provided by an embodiment of this application. The method includes the following steps:

[0044] Step S1: Obtain 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 duration.

[0045] Install three-phase current transformers, three-phase voltage transformers, and temperature transformers at the ports of the pole-mounted circuit breaker respectively, and use the three-phase current transformers, three-phase voltage transformers, and temperature transformers to collect the three-phase current data, three-phase voltage data, and temperature data at the ports of the pole-mounted circuit breaker at all acquisition moments within a preset duration. Among them, the acquisition frequency of the three-phase current data and the three-phase voltage data is set to F, and the acquisition frequency of the temperature data is set to f.

[0046] It should be noted that the values of the preset duration, the acquisition frequency F of the three-phase current data and the three-phase voltage data, and the acquisition frequency f of the temperature data are all set artificially. In this embodiment, the value of the preset duration is 1 h, the value of the acquisition frequency F of the three-phase current data and the three-phase voltage data is 1 KHz, and the acquisition frequency of the temperature data is 1 Hz. Implementers can also set them according to specific situations, and this embodiment does not make special restrictions.

[0047] Furthermore, in order to eliminate the influence of data dimensions on subsequent analysis, the z-score normalization method is used to normalize all data. Among them, the z-score normalization method is a well-known technology in the field of data processing, and its specific principle process will not be elaborated here.

[0048] Step S2: For each phase current, form each current sequence by combining the current data of each phase at every adjacent load change moment and all the acquisition moments between them. Based on the change trends of all the current data in each current sequence, determine the trend vector. By analyzing the correlation between the current sequences with the same number of each phase current and the other phase currents, as well as the change trends of all the current data in each current sequence, determine the change correlation. Analyze the correlation between the trend vectors with the same number of each phase current and the other phase currents within any time period, as well as the distribution of all the current data in each current sequence, determine the response similarity, and combine the change correlation to determine the response synchronization factor.

[0049] During the operation of the pole-mounted circuit breaker, the load of the power system may change normally with the peak and valley of the power grid power consumption. The three-phase current and voltage of the power line will change slowly with the normal fluctuation of the power system, and still satisfy the three-phase current balance state during this period.

[0050] Specifically, under ideal conditions, the three-phase current will maintain a high degree of symmetry when the power grid load fluctuates, that is, the change amplitudes of each phase current are relatively balanced. In actual situations, when the power system load changes normally with the peak and valley of the power grid, the phase currents of each phase will all have relatively high synchronous fluctuation changes. That is, when the phase current of a certain phase generates a transient response change, the change degrees of the phase currents of the remaining two phases are relatively similar, and the changes of each phase current caused by normal load changes can quickly return to the stable state within a short time.

[0051] At this time, if the fault threshold of the pole-mounted circuit breaker port is set as a constant threshold, it is easily interfered by the transient response phenomenon caused by the rapid change of the power system load with the peak and valley of the power grid, mistakenly thinking that the power system line is short-circuited or other faults and performing a tripping operation, resulting in a malfunction fault and interfering with the reliable operation of the power system.

[0052] Therefore, in order to exclude the situation of misjudging the normal response fluctuation phenomenon of the current caused by the change of the power system load with the peak and valley of the power grid as a pole-mounted circuit breaker fault, by analyzing the correlation between the current sequences with the same number of different phase currents and the correlation of the trend vectors, and combining the change trends and distributions of all the current data in the current sequence, determine the response synchronization factor of each phase current within any time period to characterize the fluctuation of each phase current. Specifically:

[0053] S201: Determine all the load change moments of each phase current within any time period, and form each current sequence of each phase current by combining the current data of each phase at every adjacent load change moment and all the acquisition moments between them. Based on the change trends of all the current data in each current sequence, determine the trend vector of each phase current within any time period.

[0054] First, in order to analyze the local changes of the phase current data, the preset time period is evenly divided into N time periods;

[0055] It should be noted that the values of N and K are both set artificially. In this embodiment, the value of N is 30. Since the length of the preset time period in this embodiment is 1 h, when the preset time period is divided into 30 time periods, the length of each time period is 2 min. The implementer can also set the division value N according to the specific situation, and this embodiment does not make special restrictions.

[0056] Secondly, in order to more intuitively analyze the change trend of the current data, the phase current data at all acquisition moments within any time period are fitted to obtain the phase current fitting curves, the slope at each acquisition moment on the phase current fitting curves is calculated, and the standard deviation and mean value of the slopes at all acquisition moments are calculated. The acquisition moment corresponding to the slope greater than the sum of the mean value and three times the standard deviation is used as the load change moment. It should be noted that there are many common fitting methods. In this embodiment, the least squares fitting is used to fit the phase current data. The implementer can also use other fitting methods such as polynomial function fitting. This embodiment does not make special restrictions on the selection of the fitting method.

[0057] Among them, the abscissa of the current fitting curve represents the acquisition moment, and the ordinate represents the fitting value of the current data.

[0058] In addition, it should be understood that calculating the slope at each acquisition moment on the phase current fitting curve essentially refers to the slope at the corresponding points of each acquisition moment on the current fitting curve. There are also many methods for calculating the slope at each acquisition moment on the phase current fitting curve. The slope of the tangent line at the point on the current fitting curve can be calculated, or the method of first-order derivative can be used to calculate the slope at any point on the curve. In this embodiment, the method of first-order derivative is used to calculate the slope at any point on the curve. The implementer can also select a suitable method according to the specific situation, and this embodiment does not make special restrictions.

[0059] Among them, the least squares fitting and the first-order derivative are both well-known technologies, and their specific principle steps will not be elaborated.

[0060] Furthermore, for the convenience of analysis, the phase current data at each adjacent load change moment and all acquisition moments between them are used to form each current sequence of the phase current;

[0061] In particular, since there are significant differences in the quantity of the phase current data before the first load change moment and after the last load change moment within the preset time period compared with the phase current data between adjacent load change moments, the phase current data before the first load change moment and after the last load change moment within the preset time period are not analyzed.

[0062] S202: During any time period, number all the current sequences and all the trend vectors of each phase current respectively. By analyzing the correlation between the current sequences with the same number among each phase current and all the other phase currents, as well as the change trend of all the current data in each current sequence of each phase current, determine the change correlation of each current sequence in each phase current during any time period.

[0063] First, in order to analyze the intensity of the local change trend of each phase current, take each current sequence of each phase current during any time period as the input of the time series decomposition algorithm, output the trend intensity of each current sequence, and form the trend vector of each phase current during any time period with the trend intensities of all the current sequences of each phase current during any time period.

[0064] 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 sequence. Implementers can also use the SEATS decomposition method to analyze the change trend of each current sequence. There is no special limitation on the selection of the time series decomposition algorithm in this embodiment.

[0065] 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 elaborated here.

[0066] Furthermore, in order to analyze the local correlation between different phase currents and thus judge whether there is an abnormality in the current fluctuation, therefore, during any time period, number all the current sequences and all the trend vectors of each phase current in ascending order of time, calculate the cumulative sum of the correlations of the current sequences with the same number between each phase current and all the other phase currents during any time period, and record it as the correlation sum value of the current sequences with the same number of each phase current during any time period;

[0067] It should be noted that there are many methods to measure the correlation between sequences. In this embodiment, the Pearson correlation coefficient between the current sequences with the same number between each phase current and all the other phase currents is calculated to measure the correlation between the current sequences with the same number of different phase currents. Implementers can also use the Spearman correlation coefficient or the Kendall rank correlation coefficient to measure the correlation between different sequences. There is no special limitation on the selection of the method to measure the correlation between sequences in this embodiment.

[0068] Among them, the calculation process of the Pearson correlation coefficient is a well-known technology, and its specific calculation steps will not be elaborated here.

[0069] Further, in order to analyze the chaos degree of the change of current data to judge whether there is an abnormal current fluctuation, so as to more accurately detect whether there is a fault in the pole-mounted circuit breaker, therefore, the information entropy of the slope at the corresponding acquisition time of all current data in each current sequence of each-phase current in any time period is calculated;

[0070] The ratio of the correlation sum value of each current sequence of each-phase current in any time period to the information entropy is used as the change correlation of each current sequence in each-phase current in any time period.

[0071] It can be understood from the change correlation of each current sequence in each-phase current in any time period that the smoother the process of any one-phase current returning to the stable state, the weaker the chaos of the slope of the current data of this phase, 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 certain phase to change, the higher the correlation of the change of the phase currents of the other phases, the larger the cumulative result of the correlation between the phase p current and all current sequences corresponding to the phase currents of the other phases, and the greater the change correlation, indicating that the current fluctuation is normal, and the change of the three-phase current is more likely to be caused by the normal change of the grid load rather than the failure of the power line. After the phase currents change, they are more likely to synchronously return to the stable state;

[0072] On the contrary, the greater the oscillation degree of the process of any one-phase current returning to the stable state, the stronger the chaos of the slope of the phase current data of this phase, that is, the larger the information entropy; at the same time, when the normal change of the grid load causes the phase current of a certain phase to change, the lower the correlation of the change of the phase currents of the other phases, the smaller the cumulative result of the correlation between the phase p current and all current sequences corresponding to the phase currents of the other phases, and the smaller the change correlation, indicating that the change of the three-phase current is more likely to be caused by the failure of the power line.

[0073] S203: Analyze the similarity of the trend vectors with the same number between each-phase current and all the 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 combine the change correlation to determine the response synchronization factor of each-phase current in any time period.

[0074] Calculate the cumulative sum of the similarities between the trend vectors with the same number between each-phase current and all the other-phase currents in any time period, and record it as the cumulative correlation sum of the trend vectors with the same number in any time period;

[0075] It should be noted that there are many methods to measure the similarity between vectors. In this embodiment, the Jaccard similarity coefficient between the trend vectors with the same number among each phase current and all the other currents is calculated to measure the similarity degree of the trend vectors with the same number between different phase currents. Implementers can also use other methods to measure the similarity degree between vectors, such as cosine similarity. Regarding the selection of methods to measure the similarity degree between vectors, no special restrictions are imposed in this embodiment.

[0076] Among them, the calculation process of the Jaccard similarity coefficient is a well-known technology, and its specific calculation steps will not be elaborated here.

[0077] Furthermore, in each current sequence of each phase current within any time period, calculate the mean value of the current data at all acquisition times except the load change moments, denoted as the current mean value, and take the accumulated sum of the differences between the current data at all load change moments in each current sequence and the current mean value as the difference sum value of each current sequence of each phase current within any time period;

[0078] 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 current data at all load change moments in each current sequence and the current mean value is calculated to measure the difference between the current data at the load change moments and the current mean value. Implementers can also use other methods to measure the difference between data, such as ratio, square of the difference, etc. Regarding the selection of methods to measure the difference between data, no special restrictions are imposed in this embodiment.

[0079] Take the ratio of the relevant accumulated sum and the difference sum value of each current sequence of each phase current within any time period as the response similarity of each current sequence of each phase current within any time period.

[0080] From the response similarity of each current sequence of each phase current within any time period, it can be understood that when the grid load changes normally and causes a change in the phase current of any one phase at the pole-mounted circuit breaker port, the phase currents of the other phases will also change accordingly. Then, the greater the accumulated sum of the similarity between the trend vectors with the same number among each phase current and all the other currents within any time period, the more similar the process of each phase current returning to the stable state after being affected by the transient interference caused by the normal change of the power system load, and the greater the response similarity; and the smaller the mutation degree of each phase current, the easier it is to return to the normal state after the mutation, that is, the smaller the difference sum value, the greater the response similarity;

[0081] Conversely, when the normal change of the power grid load causes a change in the phase current of any one phase at the pole-mounted circuit breaker port, the phase currents of the other phases will not change accordingly. Then, the smaller the cumulative sum of the similarities between the phase currents and the trend vectors of the same number among all the other currents in any time period, the greater the difference in the process of returning to the stable state after being affected by the transient interference caused by the normal change of the power system load, and the smaller the response similarity. Moreover, the greater the degree of mutation of the phase currents, the less likely it is to return to the normal state after the mutation, that is, the greater the difference sum value, and the smaller the response similarity.

[0082] Furthermore, in order to judge whether there is 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:

[0083] The response synchronization factor of each phase current in time period i is expressed as: ; in the formula, represents the change correlation of the jth current sequence in the pth phase current in 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 pth phase current in time period i.

[0084] Furthermore, it can be understood from the response synchronization factor of each phase current in any time period that when the change of the three-phase current is more likely to be caused by the normal change of the power grid load rather than the failure of the power line, it is easier for the phase currents to synchronously return to the stable state after the change, that is, the greater the change correlation and the greater the response similarity, then the greater the response synchronization factor; conversely, when the change of the three-phase current is more likely to be caused by the failure of the power line, it is less likely for the phase currents to synchronously return to the stable state after the change, that is, the smaller the change correlation and the smaller the response similarity, then the smaller the response synchronization factor.

[0085] Step S3: In any time period, analyze the differences in the amplitudes of each phase voltage at different frequencies in the frequency domain, determine the oscillation difference coefficient of each phase voltage in any time period, and combine the difference between the dispersion degree of all temperature data and the maximum temperature data, as well as the extreme distribution and dispersion degree of each phase voltage data, to determine the low-frequency stability of each phase voltage in any time period.

[0086] Grid interconnection is one of the important foundations of the smart grid. Grid interconnection can not only optimize the allocation of power resources but also enhance the reliability of the overall grid operation. However, grid interconnection will also cause changes in the power system load. At this time, relying solely on the response of the three-phase current at the pole-mounted circuit breaker port to restore the synchronous state of each phase current is not sufficient to comprehensively and accurately evaluate the normal change situation of the power system; when the power system load changes normally due to grid interconnection, the low-frequency oscillation phenomenon of the voltage fluctuations of each phase can more accurately reflect the voltage stability of the power system. However, the external environmental temperature may cause the voltage data collected at the pole-mounted circuit breaker port to be severely affected by noise, affecting the accuracy of the voltage low-frequency oscillation analysis.

[0087] Specifically, during the grid interconnection process, it usually involves cross-regional power dispatching, which causes changes in the power system load. The negative damping factors in the power system may cause the low-frequency oscillation phenomenon of the three-phase voltage. The continuous accumulation of this phenomenon will weaken the operation stability of the power system, thereby affecting the operation of the power system. When the oscillation phenomenon of the energy amplitude of the frequency components of each phase voltage spectrum within the preset frequency range is less severe, and at the same time, the abnormal high-temperature condition at the pole-mounted circuit breaker port is more ambiguous, it indicates that the current pole-mounted circuit breaker is less affected by the external high temperature, the accuracy of the obtained voltage data is higher, the voltage low-frequency oscillation of the power system is more ambiguous, and the stability of the power system is stronger.

[0088] Based on the above analysis, the amplitude of each phase voltage data at all frequencies within the preset frequency range in the frequency domain at any time period is denoted as the low-frequency amplitude;

[0089] Furthermore, by analyzing the differences between the amplitudes of each phase voltage at different frequencies in the frequency domain, the oscillation difference coefficient of each phase voltage at any time period is determined. Specifically:

[0090] The oscillation difference coefficient of the p-phase voltage in time period i The expression is: ; In the formula, 、 respectively represent the difference between the xth low-frequency amplitude in the p-phase voltage in time period i and the amplitude corresponding to the maximum frequency in the frequency domain of the p-phase voltage data, and the difference between the yth low-frequency amplitude and the amplitude corresponding to the maximum frequency in the frequency domain of the p-phase voltage data; represents the number of all low-frequency amplitudes of the p-phase voltage in the frequency domain in time period i.

[0091] 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 x-th low-frequency amplitude and the y-th low-frequency amplitude in the p-th phase voltage and the amplitude corresponding to the maximum frequency in the frequency domain of the p-th phase voltage data is calculated respectively to measure the difference between each low-frequency amplitude and the amplitude corresponding to the maximum frequency in the frequency domain of the corresponding phase voltage data. Implementers can also use other methods to measure the difference between data, such as ratios and squares of differences. Regarding the selection of methods for measuring the difference between data, this embodiment does not make special restrictions.

[0092] From the oscillation difference coefficient of each phase voltage within any time period, it can be understood that when the grid interconnection causes normal changes in the power system load, the higher the low-frequency oscillation stability of each phase voltage in the three-phase voltage, the smaller the fluctuation of the energy amplitude of the low-frequency frequency components within each phase voltage in the three-phase voltage, that is, the smaller the gap between the differences between the x-th low-frequency amplitude and the y-th low-frequency amplitude in the p-th phase voltage and the amplitude corresponding to the maximum frequency in the frequency domain of the p-th phase voltage data, that is the smaller it is, the smaller the oscillation difference coefficient; conversely, when the grid interconnection causes abnormal changes in the power system load, 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 components within each phase voltage in the three-phase voltage, that is, the greater the gap between the differences between the x-th low-frequency amplitude and the y-th low-frequency amplitude in the p-th phase voltage and the amplitude corresponding to the maximum frequency in the frequency domain of the p-th phase voltage data, that is the greater it is, the greater the oscillation difference coefficient.

[0093] Furthermore, take the reciprocal of the product of the range and the interquartile range of the phase voltage data at all acquisition moments of the pole-mounted circuit breaker within any time period, and denote it as the change concentration of each phase voltage within any time period;

[0094] Among them, the calculation process of the interquartile range is a well-known technology, and its specific calculation steps will not be elaborated here.

[0095] Furthermore, based on the oscillation difference coefficient of each phase voltage within any time period, and combining the difference between the dispersion degree of all temperature data and the maximum temperature data, as well as the extreme distribution and dispersion degree of each phase voltage data, determine the low-frequency stability of each phase voltage within any time period, specifically:

[0096] The low-frequency stability of the p-th phase voltage in time period i The expression is: ; where represents the ratio of the standard deviation to the maximum value of the temperature data at all acquisition moments within time period i; represents the change concentration of the p-th phase voltage within time period i; represents the oscillation difference coefficient of the p-th phase voltage within time period i; represents a preset constant greater than 0, used to prevent the denominator from being 0, The value of is artificially set. In this embodiment, the value of

[0097] is 0.01. On the premise of ensuring that the denominator is not zero and does not overly affect the calculation result, the implementer can also set it according to the specific situation by himself / herself, and this embodiment does not make special restrictions.

[0098] Step S4: Detect the pole-mounted circuit breaker based on the response synchronization factor of all phase currents and the low-frequency stability of all phase voltages within any time period.

[0099] When the pole-mounted circuit breaker is detecting the power line, the stronger the response synchronization recovery of each phase current and the less affected by the high-temperature anomaly of the external environment, and the stronger the stability of each phase voltage, it means that the changes in current and voltage in the power line are more likely to be caused by normal changes in the power grid load or grid interconnection rather than power line faults. At this time, if the pole-mounted circuit breaker executes a tripping operation, it means that the possibility of misoperation fault of the pole-mounted circuit breaker is higher.

[0100] Therefore, for the misoperation fault coefficient of the pole-mounted circuit breaker, it can be determined by the response synchronization factor of each phase current in the three-phase current and the stability of each phase voltage in the three-phase voltage. Specifically:

[0101] Calculate the sum value of the response synchronization factors of all phase currents within any time period and the sum value of the low-frequency stability of all phase voltages, and use the normalized value of the product of the sum value of the response synchronization factors and the sum value of the low-frequency stability as the misoperation fault coefficient of the pole-mounted circuit breaker within any time period;

[0102] When the fluctuations of three-phase current and three-phase voltage caused by the load change of the power system are more likely to be caused by the normal change of the grid load or grid interconnection rather than the power line fault, the higher the possibility that the pole-mounted circuit breaker performs a tripping action is a misoperation fault, that is, the misoperation fault coefficient is larger; the stronger the correlation of the currents of each phase in the three-phase current at the port of the pole-mounted circuit breaker, the stronger the similarity of the responses of the currents of each phase, 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 of each phase in the three-phase voltage, the stronger the low-frequency stability, and the less affected by 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.

[0103] Preferably, the schematic diagram of the misoperation fault coefficient extraction process provided in this embodiment is as Figure 2 shown.

[0104] Furthermore, take the misoperation fault coefficients of the pole-mounted circuit breaker in all time periods within the preset time duration as the input of the threshold segmentation algorithm, and output the segmentation threshold. If the misoperation fault coefficient is greater than or equal to the segmentation threshold, the pole-mounted circuit breaker fails during the corresponding time period; otherwise, the pole-mounted circuit breaker is normal during the corresponding time period.

[0105] 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. Implementers can also use other threshold segmentation algorithms to classify the misoperation fault coefficients. There is no special limitation on the selection of the threshold segmentation algorithm in this embodiment.

[0106] Based on the same inventive concept as the above method, the embodiment of the present application also provides a multi-functional detection device for a pole-mounted circuit breaker, 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 multi-functional detection methods for the pole-mounted circuit breaker.

[0107] It should be noted that: the above sequence of the embodiments of the present application is only for description and does not represent the advantages or disadvantages of the embodiments. And the above 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 embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0108] Each embodiment in this specification is described in a progressive manner. The same or similar parts between each embodiment can be referred to each other. The key point of each embodiment is to illustrate the differences from other embodiments.

[0109] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application shall be included within 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, and determine the response similarity of each current sequence in each phase current in any period. 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; 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. The inverse of the product of the range and the interquartile moment of each phase voltage data at all acquisition times of the pole-mounted circuit breaker in any period of time is taken as the concentration of change, which is recorded as the concentration of change of each phase voltage in any period of time. The expression of the low-frequency stability of each phase voltage in any period of time 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 constant greater than 0; The normalized value of the product of the sum of the response synchronization factors of all phase currents in any time period and the sum of the low-frequency stability of all phase voltages is used as the false operation fault coefficient of the pole-mounted circuit breaker in any time period; the false operation fault coefficient of the pole-mounted circuit breaker in all time periods within a 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.

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 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.

7. 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 6 are implemented.

Images