10kV capacitor bank circuit breaker non-full-phase opening monitoring method and device

Abstract

The invention discloses a 10kV capacitor bank circuit breaker non-full-phase opening monitoring method and device, and relates to the field of circuit breaker control, and the method comprises the steps: obtaining the bus current data of a 10KV capacitor bank circuit breaker; performing wavelet transformation on the bus current data to obtain a wavelet coefficient; extracting the energy distribution characteristic quantity of the bus current according to the wavelet coefficient, and calculating the energy distribution mean square error of each phase according to the energy distribution characteristic quantity; subtracting the energy distribution mean square error of each phase from a preset steady-state energy distribution mean square error when each phase is not switched off, and comparing a difference value result with a preset threshold value to obtain a judgment vector of the 10KV capacitor bank circuit breaker; wherein the judgment vector comprises three elements of A, B and C phases; and monitoring the non-full-phase opening state of the 10KV capacitor bank circuit breaker according to the judgment vector. According to the method, the problem that a certain phase fault cannot be accurately and reliably positioned in the prior art in the non-full-phase opening fault monitoring of the circuit breaker is solved.

Description

Technical Field

[0001] The present invention relates to the field of circuit breaker control, and more specifically, to a method and device for monitoring non-full-phase opening of a 10kV capacitor bank circuit breaker. Background Art

[0002] At present, in the field of reactive power compensation, parallel capacitor devices are widely used to compensate reactive power, improve power factor and maintain voltage level, which leads to frequent operation of 10 kV compensation capacitor bank circuit breakers, which makes the failure rate of such circuit breakers far exceed that of other types of circuit breakers, seriously affecting the success rate of capacitor bank switching. Among the common faults of circuit breakers, the non-full-phase disconnection fault of vacuum circuit breakers is particularly complex and harmful. When maintaining or inspecting equipment, if the staff mistakenly thinks that all phases have been disconnected, but in fact some phases are still energized, electric shock may occur. Among all capacitor bank circuit breaker failure accidents, non-full-phase disconnection accidents caused by mechanical structure reasons account for nearly 21%, posing a huge threat to the safety of maintenance personnel. However, because this kind of fault is often accompanied by uneven voltage and current distribution in the three-phase circuit, it is difficult for traditional power grid fault detection methods to realize non-full-phase disconnection monitoring of circuit breakers. At present, the maintenance of circuit breakers mainly relies on regular preventive inspections, which is costly, has a long maintenance cycle, and cannot accurately locate potential faults and their exact locations in a timely manner.

[0003] At present, the monitoring of the non-full-phase disconnection fault of the capacitor bank circuit breaker uses a logical digital circuit to realize the display of various non-full-phase disconnections of the circuit breaker. However, this method requires the measurement of many electrical parameters, and can only distinguish one phase not disconnected, two phases not disconnected, all disconnected, and all not disconnected, but cannot distinguish the working condition of a specific phase not disconnected. Alternatively, by collecting the real-time operation data of the power grid switch equipment to determine whether the switch is non-full-phase disconnected, the disadvantage is that too much real-time operation data is required for judgment, and the judgment process is relatively complicated, and it is impossible to quickly respond to the judgment of the disconnection. Summary of the invention

[0004] The purpose of the present invention is to provide a 10kV capacitor bank circuit breaker non-full-phase opening monitoring method and device to solve the problem that the prior art cannot accurately and reliably locate a phase fault in the circuit breaker non-full-phase opening fault monitoring.

[0005] In a first aspect of the present application, a method for monitoring non-full-phase opening of a 10KV capacitor bank circuit breaker is provided, the method comprising:

[0006] Obtain bus current data of 10KV capacitor bank circuit breaker;

[0007] Perform wavelet transform on bus current data to obtain wavelet coefficients;

[0008] The energy distribution characteristic quantity of the bus current is extracted according to the wavelet coefficient, and the mean square error of the energy distribution of each phase is calculated according to the energy distribution characteristic quantity;

[0009] The mean square error of energy distribution of each phase is subtracted from the mean square error of steady-state energy distribution when each phase is not disconnected, and the difference results are compared with the preset thresholds to obtain the judgment vector of the 10KV capacitor bank circuit breaker; wherein the judgment vector includes three elements of the three phases A, B, and C;

[0010] The non-full-phase opening state of the 10KV capacitor bank circuit breaker is monitored according to the judgment vector.

[0011] In one implementation, the bus current data is subjected to wavelet transformation to obtain wavelet coefficients, specifically, determining the wavelet basis function and the number of decomposition layers;

[0012] The bus current data is decomposed by wavelet according to the wavelet basis function and the number of decomposition levels to obtain the wavelet coefficients.

[0013] In one implementation, the energy distribution characteristic quantity of the bus current is extracted according to the wavelet coefficients, including: determining the wavelet coefficients of the low-frequency part of each layer and the wavelet coefficients of the high-frequency part of each layer;

[0014] The squares of the wavelet coefficients of the low-frequency part and the high-frequency part are summed respectively to obtain the energy distribution characteristic of the bus current.

[0015] In one implementation, the expression for calculating the mean square error of energy distribution is:

[0016] Among them, V is the mean square error of energy distribution, N is the number of decomposition layers, and v i is the energy distribution characteristic of each layer, and μ is the mean of all energies.

[0017] In one implementation, monitoring the non-full-phase opening state of the 10KV capacitor bank circuit breaker according to the judgment vector includes:

[0018] If the difference result is less than the preset threshold, the corresponding element of the judgment vector is taken as 0, indicating that the circuit breaker of the corresponding phase is not opened;

[0019] If the difference result is greater than the preset threshold, the corresponding element of the judgment vector takes the value of 1, indicating that the circuit breaker of the corresponding phase is open.

[0020] In a second aspect of the present application, a 10KV capacitor bank circuit breaker non-full-phase opening monitoring device is provided, the device comprising:

[0021] A data acquisition module is used to acquire bus current data of a 10KV capacitor bank circuit breaker;

[0022] A data processing module is used to perform wavelet transform on bus current data to obtain wavelet coefficients;

[0023] A mean square error calculation module is used to extract the energy distribution characteristic quantity of the bus current according to the wavelet coefficient, and calculate the mean square error of the energy distribution of each phase according to the energy distribution characteristic quantity;

[0024] The judgment vector calculation module is used to make a difference between the mean square error of energy distribution of each phase and the preset mean square error of steady-state energy distribution when each phase is not disconnected, and compare the difference results with the preset thresholds to obtain the judgment vector of the 10KV capacitor bank circuit breaker; wherein the judgment vector includes three elements of the three phases A, B, and C;

[0025] The status monitoring module is used to monitor the non-full-phase opening status of the 10KV capacitor bank circuit breaker according to the judgment vector.

[0026] In one implementation, the data processing module further includes:

[0027] Selection module, used to determine the wavelet basis function and the number of decomposition layers;

[0028] The decomposition module is used to perform wavelet decomposition on the bus current data according to the wavelet basis function and the number of decomposition layers to obtain wavelet coefficients.

[0029] In one implementation, the mean square error calculation module further includes:

[0030] A coefficient determination module, used to determine the wavelet coefficients of the low-frequency part of each layer and the wavelet coefficients of the high-frequency part of each layer;

[0031] The characteristic quantity calculation module is used to sum the squares of the wavelet coefficients of the low-frequency part and the high-frequency part respectively to obtain the energy distribution characteristic quantity of the bus current.

[0032] In one implementation, the expression for calculating the mean square error of energy distribution is:

[0033] Among them, V is the mean square error of energy distribution, N is the number of decomposition layers, and v i is the energy distribution characteristic of each layer, and μ is the mean of all energies.

[0034] In one implementation, the status monitoring module is specifically used to:

[0035] If the difference result is less than the preset threshold, the corresponding element of the judgment vector is taken as 0, indicating that the circuit breaker of the corresponding phase is not opened;

[0036] If the difference result is greater than the preset threshold, the corresponding element of the judgment vector takes the value of 1, indicating that the circuit breaker of the corresponding phase is open.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] This application aims at the problem of insufficient accuracy and reliability of the monitoring of non-full-phase disconnection of existing capacitor bank circuit breakers. The bus current data near the circuit breaker is obtained through the relevant current measurement device of the distribution network automation technology, and the wavelet transform technology is used for data processing. Then, the energy distribution characteristic quantity is calculated according to the wavelet coefficient, and the energy distribution mean square error of each phase is determined in combination with the energy distribution characteristic quantity. The mean square error of the steady-state energy distribution when all three phases are not disconnected is used as the comparison vector, and finally the judgment vector is calculated. The monitoring of the non-full-phase disconnection of the circuit breaker is realized through the judgment vector. Therefore, the present application can accurately identify the non-full-phase disconnection fault of the circuit breaker, and compared with the prior art, the present method can accurately locate a specific phase. Even when the harmonic content of the power system changes, the non-full-phase disconnection state of the circuit breaker can still be accurately identified, with high reliability. In addition, since the required data can be directly obtained from the current measurement device of the distribution network automation system, this greatly simplifies the data acquisition process, thereby reducing the overall cost of technical implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0040] Figure 1 A flow chart of a method for monitoring non-full-phase opening of a 10KV capacitor bank circuit breaker provided in an embodiment of the present application;

[0041] Figure 2 A schematic diagram of a reactive power compensation simulation circuit for a 10kV container group circuit breaker provided in an embodiment of the present application;

[0042] Figure 3 A schematic diagram of energy distribution characteristic quantities when all three phases are not disconnected and all three phases are disconnected provided in an embodiment of the present application;

[0043] Figure 4 A schematic diagram of energy distribution characteristic quantities when not all phases are fully switched off provided in an embodiment of the present application;

[0044] Figure 5 A principle block diagram of a 10KV capacitor bank circuit breaker non-full-phase opening monitoring device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0046] It should be noted that the terms "include" or "may include" used in various embodiments of the present application indicate the presence of the function, operation or element applied for, and do not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates are only intended to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items.

[0047] Please refer to Figure 1 , Figure 1 A flow chart of a non-full-phase opening monitoring method for a 10KV capacitor bank circuit breaker provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the method includes:

[0048] S101, obtaining bus current data of a 10KV capacitor bank circuit breaker.

[0049] In this embodiment, the bus current data of the 10KV capacitor bank circuit breaker can be obtained through relevant current measurement devices, such as supervisory control and data acquisition (SCADA), feeder automation (FA) and other devices, and no redundant explanation is given in this embodiment.

[0050] S102, performing wavelet transform on bus current data to obtain wavelet coefficients.

[0051] In this embodiment, when performing wavelet transform, it is necessary to first determine a suitable wavelet basis function and the number of decomposition levels. Therefore, this embodiment selects the Db4 wavelet basis function as the basic wavelet function.

[0052] When determining the number of decomposition layers, the present invention sets the sampling frequency to 6400 Hz and the base frequency to 50 Hz. In order to make the base frequency located at the center of the lowest sub-band and limit the influence of the base frequency component on other sub-bands, the wavelet decomposition frequency band division method can be expressed as formula (1):

[0053] Among them, f s is the sampling frequency, f0 is the signal fundamental frequency. Substituting into the calculation, we can get P = 6, so in order to achieve good classification accuracy, 7-layer wavelet decomposition is used.

[0054] Then, the bus current data can be decomposed by wavelet according to the determined wavelet basis function and decomposition layer number to obtain the wavelet coefficients.

[0055] S103, extracting energy distribution characteristics of bus current according to wavelet coefficients, and calculating mean square error of energy distribution of each phase according to the energy distribution characteristics.

[0056] In this embodiment, a set of energy distribution characteristics is constructed according to the wavelet coefficients determined in the above embodiment. The construction process is specifically as follows: determine the wavelet coefficients of the low-frequency part of each layer and the wavelet coefficients of the high-frequency part of each layer; sum the squares of the wavelet coefficients of the low-frequency part and the high-frequency part respectively to obtain the energy distribution characteristics of the bus current.

[0057] The following formula describes the above process:

[0058] in, c j (n) represents the wavelet coefficient of the low-frequency approximation part of the jth layer, d x (n) represents the wavelet coefficients representing the high-frequency details of the j-th layer.

[0059] In order to quantify the feature extraction results and better distinguish the feature extraction results in different situations, this embodiment calculates the mean square error of energy distribution according to the wavelet coefficients, where the expression for calculating the mean square error of energy distribution is:

[0060] Among them, V is the mean square error of energy distribution, N is the number of decomposition layers, and v i is the energy distribution characteristic of each layer, and μ is the mean of all energies.

[0061] S104, subtract the mean square error of the energy distribution of each phase from the preset mean square error of the steady-state energy distribution when all phases are not disconnected, and compare the difference results with the preset thresholds to obtain the judgment vector of the 10KV capacitor bank circuit breaker; wherein the judgment vector includes three elements of the three phases A, B, and C.

[0062] In this embodiment, the preset mean square error threshold of energy distribution when each phase is not disconnected can define a comparison vector, and accordingly, the calculated mean square error of energy distribution is the actual vector, wherein the ABC three-phase of the circuit breaker has a comparison vector and an actual vector. In order to weaken the influence of factors such as load size and current size, the actual vector and the comparison vector can be made to differ. If there is no influence of factors such as power system noise, the difference between the two results can only be zero and non-zero. However, due to the dynamic changes of the power system and the difficulty in completely eliminating noise, the difference between the two results is difficult to be zero. Therefore, the energy distribution mean square error threshold M is set. When the difference result is less than M, it can be considered that the judgment vector is zero. Therefore, the judgment vector X=[X m , X n , X r] describes the difference result, and the elements of X can only be 0 or 1. The value of M can be determined by randomly adding white noise to the power system for simulation testing.

[0063] S105, monitoring the non-full-phase opening state of the 10KV capacitor bank circuit breaker according to the judgment vector.

[0064] In this embodiment, the non-full-phase opening state of the circuit breaker is distinguished according to the judgment vector, and the specific implementation method is: if X a -X A If the vector X is smaller than the preset vector threshold, then the vector X m If it is 0, it means that the current of phase A has not changed and phase A is not disconnected; if X a -X A Is not equal to 0, then the vector X m Taking 1 indicates that the current of phase A changes and phase A is disconnected. The same principle applies to the remaining two phases BC.

[0065] In addition, this embodiment also makes a monitoring example analysis based on the actual data of the substation, as follows:

[0066] First, set the parameters of each electrical equipment in the simulation model. The specific parameters of the reactive power compensation device are shown in Table 1:

[0067] Table 1 Simulation parameters

[0068] Electrical Equipment Equivalent parameters Parallel capacitors Q=8000kvar,C=106uF Series Reactor Reactance 5%, L = 2.169mH

[0069] According to the parameters in Table 1, a simulation circuit is built in MATLAB. The simulation circuit schematic is shown in Figure 2 As shown, in the simulation circuit of normal operation, the non-full-phase disconnection is simulated by controlling the circuit breaker opening time of the reactive compensation device. By measuring the bus current, data simulating the three-phase current in actual operation can be obtained. It should be noted that the circuit breaker status is divided into the following three types, namely, full three-phase disconnection, non-full-phase disconnection and all three-phase non-disconnection, for non-full-phase disconnection. Simulations were carried out for the different circuit breaker states listed above. The circuit breaker was disconnected at t=0.5 seconds, and the bus current before and after the circuit breaker was opened was analyzed by wavelet transform. First, the three-phase current of the bus is decomposed by wavelet, and then the characteristic quantity is extracted. In order to compare with the normal situation of all non-disconnection and all disconnection, Figure 3 Firstly, the characteristic extraction results of bus three-phase current in these two states are shown. Figure 3(a) shows the extraction results of bus current feature quantities when the circuit breaker is operating normally. Taking phase A as an example for analysis, after seven layers of wavelet decomposition, the results of each layer correspond to a wavelet coefficient. By calculating these wavelet coefficients, the energy distribution values ​​corresponding to each layer of phase A can be obtained. These values ​​specifically reflect the distribution of phase A current energy on each layer. From the extraction results, it can be seen that the energy is mainly concentrated in the fifth, sixth, and seventh layers, while the low-frequency energy distribution in the first four layers is less. This change in energy distribution from the first layer to the seventh layer reflects the trend of energy distribution. Figure 3 (b) shows the bus current feature extraction results when all circuit breakers are normally opened. Its energy distribution trend is similar to Figure 3 (a) Similar, but with a numerical energy distribution Figure 3 (b) with Figure 3 (a) The minimum difference is about 50%, and the relative positions of the three-phase characteristic results are also quite different, such as Figure 3 The curve of the extraction result of phase B in (a) is above the other two phases, while Figure 3 In (b), the extraction results of phase A are plotted above the other two phases. Figure 3 The two extraction results in represent the common states of the circuit breaker, so they can be compared and analyzed with the non-full-phase opening state.

[0070] When one phase of the circuit breaker is not open, Figure 4 (a) as an example, compared with Figure 4 (a), since phase A is not disconnected, the fluctuation of phase A current on the bus is small, while the fluctuation of phase B and C current is large. Therefore, Figure 4 In (a), the energy distribution trend and value change of phase A current are small, while the differences between phases B and C are large. Taking the seventh layer results as an example, the value change of phase A is about 1.5%, while that of phase B is about 56.4%, and that of phase C is about 93.7%. This also leads to changes in the relative positions of the three-phase characteristic quantity results. Figure 4 (b) and Figure 4 (c) Also, because one phase is not disconnected, the relative positions of the energy distribution values ​​of the three-phase current and the three-phase characteristic quantity results are different.

[0071] When the two phases of the circuit breaker are not disconnected, Figure 4 (d) as an example, since phases A and B are not disconnected, the fluctuation of the current of phases A and B on the bus is small, while the fluctuation of the current of phase C is large. Figure 3 (a), the difference is mainly concentrated in phase C, whose energy distribution value changes by 93.7%, and the relative positions of the three-phase characteristic results also change. Figure 4 (e) and Figure 4 (f) Figure 3The differences in (a) are concentrated in phase B and phase A. In summary, when the circuit breaker is not disconnected in one phase and two phases, there are obvious differences in the feature extraction results of the busbar three-phase current. The energy distribution trends of the currents of each phase are similar, but when the circuit breaker status is different, the energy distribution values ​​and the relative positions of the three-phase feature results are different. This feature can be used to clearly distinguish the state of non-full-phase disconnection.

[0072] After calculating the feature quantity, according to formula (3) Figure 3 and Figure 4 The extracted results are further processed to calculate the corresponding energy distribution mean square error. The results are shown in Table 2.

[0073] Table 2 Summary of mean square error of energy distribution

[0074]

[0075] After obtaining Table 2, the comparison vector X0=[1.2536, 2.5536, 0.2288] is defined, and the threshold is M=0.25, then the judgment vector can be obtained as shown in Table 3.

[0076] Table 3 Judgment vector summary table

[0077]

[0078] According to Table 3, it can be seen that no matter one phase or two phases are not opened, they can be distinguished in detail through the judgment vector, and one phase can be specifically not opened, and the final result is consistent with the actual situation.

[0079] Since the harmonic content in the actual power system is constantly changing, the harmonic content is changed and white noise is randomly added to study and analyze whether the harmonic content has an impact on the accuracy of the proposed method.

[0080] Similarly, based on the actual recorded data of a 10kV substation, the third and fifth voltage harmonic contents injected into the simulation system are changed, and then the distinction results of phase A without disconnection are summarized, as shown in Table 4.

[0081] Table 4 Summary of the results of phase A not being disconnected when different harmonic contents are present

[0082]

[0083] In Table 4, Y1 and Y2 represent the third and fifth voltage harmonic contents respectively. a -X A are all less than the energy distribution mean square error threshold M, and X b -X B , X c -XC All of them are greater than the energy distribution mean square error threshold M. According to the previous analysis, we know that all the final judgment vectors X = [0, 1, 1]. This means that even if the harmonic content keeps changing, we can finally get the judgment vector X = [0, 1, 1], that is, we can distinguish that phase A is not disconnected and phases B and C are disconnected.

[0084] Therefore, although the change in harmonic content will cause the mean square error of the energy distribution of the disconnected phase current to change, the mean square error of the energy distribution of the unconnected phase remains unchanged. Therefore, when the harmonic content changes, the method provided in this embodiment can still accurately and reliably identify the circuit breaker state, and the harmonic content will not affect the accuracy of the proposed method.

[0085] It can be seen that the method provided in this embodiment aims at the problem of insufficient accuracy and reliability of the existing capacitor group circuit breaker non-full-phase disconnection monitoring, and proposes a technology for realizing non-full-phase disconnection monitoring and identification through judgment vectors. The specific implementation method is: the bus current data near the circuit breaker is obtained through the relevant current measurement device of the distribution network automation technology, and the wavelet transform technology is used for data processing. Then, the energy distribution mean square error is calculated according to the wavelet coefficient, and the mean square error of the three-phase current energy distribution when all three phases are not disconnected is used as the comparison vector. Finally, the judgment vector is calculated to realize the monitoring of the non-full-phase disconnection of the circuit breaker through the judgment vector.

[0086] The actual calculation results show that the method provided in this embodiment can accurately identify the non-full-phase opening fault of the circuit breaker, and compared with the prior art, this method can accurately locate a specific phase. Even when the system harmonic content changes, this method can still accurately identify the non-full-phase opening state of the circuit breaker, showing high reliability. In addition, since the required data can be directly obtained from the current measurement device of the distribution network automation system, this greatly simplifies the data collection process, thereby reducing the overall cost of technical implementation.

[0087] Please refer to Figure 5 , Figure 5 The principle block diagram of a 10KV capacitor bank circuit breaker non-full-phase opening monitoring device provided in the embodiment of the present application is as follows: Figure 5 As shown, the device comprises:

[0088] The data acquisition module 510 is used to acquire the bus current data of the 10KV capacitor bank circuit breaker;

[0089] The data processing module 520 is used to perform wavelet transformation on the bus current data to obtain wavelet coefficients;

[0090] A mean square error calculation module 530 is used to extract the energy distribution characteristic quantity of the bus current according to the wavelet coefficient, and calculate the mean square error of the energy distribution of each phase according to the energy distribution characteristic quantity;

[0091] The judgment vector calculation module 540 is used to make a difference between the mean square error of energy distribution of each phase and the preset mean square error of steady-state energy distribution when each phase is not disconnected, and compare the difference results with the preset thresholds to obtain the judgment vector of the 10KV capacitor bank circuit breaker; wherein the judgment vector includes three elements of the three phases A, B, and C;

[0092] The state monitoring module 550 is used to monitor the non-full-phase opening state of the 10KV capacitor bank circuit breaker according to the judgment vector.

[0093] It can be seen that a 10KV capacitor bank circuit breaker non-full-phase opening monitoring device provided in the embodiment of the present application aims at the problem of insufficient accuracy and reliability of the existing capacitor bank circuit breaker non-full-phase opening monitoring. The bus current data near the circuit breaker is obtained through the relevant current measuring device of the distribution network automation technology, and the wavelet transform technology is used for data processing. Then, the energy distribution mean square error is calculated according to the wavelet coefficient, and the three-phase current energy distribution mean square error when all three phases are not opened is used as the comparison vector. Finally, the judgment vector is calculated to realize the monitoring of the non-full-phase opening of the circuit breaker through the judgment vector. Therefore, the present application can accurately identify the non-full-phase opening fault of the circuit breaker, and compared with the prior art, the present method can accurately locate a specific phase. Even when the harmonic content of the power system changes, the non-full-phase opening state of the circuit breaker can still be accurately identified, with high reliability. In addition, since the required data can be directly obtained from the current measuring device of the distribution network automation system, this greatly simplifies the data acquisition process, thereby reducing the overall cost of technical implementation.

[0094] In some embodiments, the data processing module 520 further includes:

[0095] Selection module, used to determine the wavelet basis function and the number of decomposition layers;

[0096] The decomposition module is used to perform wavelet decomposition on the bus current data according to the wavelet basis function and the number of decomposition layers to obtain wavelet coefficients.

[0097] In some embodiments, the mean square error calculation module 530 further includes:

[0098] A coefficient determination module, used to determine the wavelet coefficients of the low-frequency part of each layer and the wavelet coefficients of the high-frequency part of each layer;

[0099] The characteristic quantity calculation module is used to sum the squares of the wavelet coefficients of the low-frequency part and the high-frequency part respectively to obtain the energy distribution characteristic quantity of the bus current.

[0100] In some embodiments, the expression for calculating the mean square error of energy distribution is:

[0101] Among them, V is the mean square error of energy distribution, N is the number of decomposition layers, and v i is the energy distribution characteristic of each layer, and μ is the mean of all energies.

[0102] In some embodiments, the status monitoring module 550 is specifically configured to:

[0103] If the difference result is less than the preset threshold, the corresponding element of the judgment vector is taken as 0, indicating that the circuit breaker of the corresponding phase is not opened;

[0104] If the difference result is greater than the preset threshold, the corresponding element of the judgment vector takes the value of 1, indicating that the circuit breaker of the corresponding phase is open.

[0105] It should be noted that the embodiment of the present application provides a 10KV capacitor bank circuit breaker non-full-phase opening monitoring device, which is similar to the above Figure 1 The 10KV capacitor group circuit breaker non-full-phase opening monitoring method shown is a technical solution based on the same inventive concept. Through the detailed description of the 10KV capacitor group circuit breaker non-full-phase opening monitoring method provided in the above embodiment, those skilled in the art can clearly understand the implementation process of each module in the 10KV capacitor group circuit breaker non-full-phase opening monitoring device in this embodiment, so for the sake of brevity of the specification, it will not be repeated here.

[0106] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A 10KV capacitor bank circuit breaker non-full-phase opening monitoring method, characterized in that the method include: Obtain bus current data of 10KV capacitor bank circuit breaker; Perform wavelet transform on bus current data to obtain wavelet coefficients; The energy distribution characteristic quantity of the bus current is extracted according to the wavelet coefficient, and the mean square error of the energy distribution of each phase is calculated according to the energy distribution characteristic quantity; The mean square error of energy distribution of each phase is subtracted from the mean square error of steady-state energy distribution when each phase is not disconnected, and the difference results are compared with the preset thresholds to obtain the judgment vector of the 10KV capacitor bank circuit breaker; wherein the judgment vector includes three elements of the three phases A, B, and C; The non-full-phase opening state of the 10KV capacitor bank circuit breaker is monitored according to the judgment vector.

2. The method according to claim 1, characterized in that Perform wavelet transform on bus current data to obtain wavelet coefficients, specifically: determine wavelet basis function and decomposition layer number; The bus current data is decomposed by wavelet according to the wavelet basis function and the number of decomposition levels to obtain the wavelet coefficients.

3. The method according to claim 2, characterized in that The energy distribution characteristic quantity of the bus current is extracted according to the wavelet coefficient, including: determining the wavelet coefficient of each layer of low-frequency part and the wavelet coefficient of each layer of high-frequency part; The squares of the wavelet coefficients of the low-frequency part and the high-frequency part are summed respectively to obtain the energy distribution characteristic of the bus current.

4. The method according to claim 1, characterized in that: The expression for calculating the mean square error of energy distribution is: Among them, V is the mean square error of energy distribution, N is the number of decomposition layers, and v i is the energy distribution characteristic of each layer, and μ is the mean of all energies.

5. The method according to claim 1, characterized in that Monitor the non-full-phase opening status of the 10KV capacitor bank circuit breaker based on the judgment vector, including: If the difference result is less than the preset threshold, the corresponding element of the judgment vector is taken as 0, indicating that the circuit breaker of the corresponding phase is not opened; If the difference result is greater than the preset threshold, the corresponding element of the judgment vector takes the value of 1, indicating that the circuit breaker of the corresponding phase is open.

6. A 10KV capacitor bank circuit breaker non-full-phase opening monitoring device, characterized in that: The device includes: A data acquisition module is used to acquire bus current data of a 10KV capacitor bank circuit breaker; A data processing module is used to perform wavelet transform on bus current data to obtain wavelet coefficients; A mean square error calculation module is used to extract the energy distribution characteristic quantity of the bus current according to the wavelet coefficient, and calculate the mean square error of the energy distribution of each phase according to the energy distribution characteristic quantity; The judgment vector calculation module is used to make a difference between the mean square error of energy distribution of each phase and the preset mean square error of steady-state energy distribution when each phase is not disconnected, and compare the difference results with the preset thresholds to obtain the judgment vector of the 10KV capacitor bank circuit breaker; wherein the judgment vector includes three elements of the three phases A, B, and C; The status monitoring module is used to monitor the non-full-phase opening status of the 10KV capacitor bank circuit breaker according to the judgment vector.

7. The device according to claim 6, characterized in that The data processing module also includes: Selection module, used to determine the wavelet basis function and the number of decomposition layers; The decomposition module is used to perform wavelet decomposition on the bus current data according to the wavelet basis function and the number of decomposition layers to obtain wavelet coefficients.

8. The device according to claim 7, characterized in that The mean square error calculation module also includes: A coefficient determination module, used to determine the wavelet coefficients of the low-frequency part of each layer and the wavelet coefficients of the high-frequency part of each layer; The characteristic quantity calculation module is used to sum the squares of the wavelet coefficients of the low-frequency part and the high-frequency part respectively to obtain the energy distribution characteristic quantity of the bus current.

9. The device according to claim 6, characterized in that The expression for calculating the mean square error of energy distribution is: Among them, V is the mean square error of energy distribution, N is the number of decomposition layers, and v i is the energy distribution characteristic of each layer, and μ is the mean of all energies.

10. The device according to claim 6, characterized in that Condition monitoring module, specifically used for: If the difference result is less than the preset threshold, the corresponding element of the judgment vector is taken as 0, indicating that the circuit breaker of the corresponding phase is not opened; If the difference result is greater than the preset threshold, the corresponding element of the judgment vector takes the value of 1, indicating that the circuit breaker of the corresponding phase is open.

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