Locating method for single-phase disconnection non-grounding fault in power distribution network

Abstract

To provide a locating method for a single-phase disconnection non-grounding fault in a power distribution network of a power system, capable of significantly reducing an operation work amount, improving locating efficiency, and achieving accurate locating.SOLUTION: A locating method for a single-phase disconnection non-grounding fault in a power distribution network of a power system includes: acquiring phase voltage information to identify a fault phase and determine a fault interval; adding white Gaussian noise to a fault transient traveling wave signal by an adaptive noise complete set empirical mode decomposition method to obtain accurate time when the signal suddenly changes; and performing initial location in the fault interval and then accurately locating a fault position within a range obtained by the initial location.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the field of fault diagnosis of distribution grid in power system, and in particular to a method for locating single-phase open-circuit ungrounded fault in distribution grid. [Background technology]

[0002] In recent years, with the rapid development of social economy and the continuous improvement of people's living standards, users have higher requirements for the reliability and safety of power grid supply. At the same time, with the promotion of power system reform and the initial formation of electricity marketization, user experience has become an important factor that power companies cannot ignore, and the power grid is directly connected to users, the importance of which has been known to power builders for the first time, and it has become an important part of the construction of the power grid.

[0003] With the widespread use of overhead insulated wires in the power distribution network, line breakage caused by natural disasters such as lightning, storms, heavy snow and hail, aging and deterioration of the line, breakage of the ceramic cross arm and destruction by external forces has become one of the common faults in the power distribution network. The power distribution network faults can basically be divided into single-phase ground faults, single-phase open circuit faults, phase-to-phase short circuit faults and complex faults. There are many types of open circuit faults, and their forms are complex and diverse. After the open circuit fault, the system operates asymmetrically, the negative-phase current in the faulty line increases rapidly, the voltage quality decreases, the damage to the three-phase operating device becomes very large, and the motor may suddenly decrease in rotation speed due to the open-phase operation and even burn out. After the open circuit fault occurs in the power distribution line, it may fall to the ground and become a more complex fault, which may cause serious accidents such as forest fires, electric shock to people and animals, and damage to equipment. In addition, there is a risk that a wire breakage fault may worsen into a phase-to-phase short circuit fault, expanding the scope of the power outage, causing long or short power outages and resulting in economic losses for users.

[0004] To ensure that the power grid operates safely and reliably, open faults need to be accurately located so that grid operators can quickly address them.

[0005] At present, research on fault location in power grids has matured, but the difficulty of fault location in power distribution grids is much higher than that in power transmission grids, because the power distribution grid has many branch circuits, a complex structure, and a relatively small fault current. According to the differences in signals used in the current fault location methods in various power distribution grids, they can generally be divided into two types: active location method and passive location method. The active location method means that a specific signal is actively input into the system after a fault, and then the status of the specific signal is detected at each point of the distribution grid line to perform fault location, while the passive location method means that the fault voltage, current, and other signals generated in the system itself after the fault are used to obtain the location where the fault occurs through theoretical derivation and algorithm design. Existing studies have been carried out from different perspectives on the location of single-phase open circuit faults in power distribution networks and have achieved some results, but there are still problems such as the noise signal for numerical analysis showing the voltage characteristics of single-phase open circuit non-grounded faults is relatively large and prone to distortion, the location accuracy of single-phase open circuit non-grounded faults in power distribution networks is insufficient, and data integration is insufficient. In addition, existing fault analysis methods are independent of each other, and the use of fault signal information acquired by existing monitoring devices is insufficient, resulting in lack of compatibility and integration. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides an intelligent diagnosis method, a fault diagnosis apparatus, a computer-readable storage medium and a computer program product for high-side faults in a power distribution transformer, so as to solve the above problems. [Means for solving the problem]

[0007] In a first aspect, the present invention provides a method for locating a single-phase open-ungrounded fault in a power distribution network, which includes the following steps 1 to 4.

[0008] Step 1: Obtain the phase voltage information at the time of fault occurrence to identify the faulty phase and determine the fault section; The phase voltage information therein is obtained from the feeder terminal (FTU) or fault indicator.

[0009] Step 1.1 Collect phase voltages and mark the detection nodes, mark the detection node at the bus exit as detection node 1, mark the adjacent detection node as detection node 2, and mark the remaining detection nodes one by one in this analogy, and mark the last detection node as detection node n; Step 1.2: Let the detection node 1 be k, where k=1, Step 1.5: If any one of the above three conditions is satisfied, determine that the fault section is the section between detection node k and detection node k-1, and end the determination. Otherwise, let k=k+1, If k≦n, continue to execute step 1.3; If k>n, it is directly determined that the fault section is the section from the detection node n to the end of the line, and the determination is terminated.

[0010] Step 2 Add white Gaussian noise to the fault transient traveling wave signal by adaptive noise complete set empirical mode decomposition method to obtain the exact time when the signal suddenly changes, which is specifically: White Gaussian noise is added to the collected fault transient traveling wave signal to obtain the signal x(t) to be decomposed, and then adaptive noise complete ensemble empirical mode decomposition is performed on the signal x(t) to be decomposed to obtain the intrinsic mode functions of multiple intrinsic mode components, from which the low-frequency meaningful signals are extracted to obtain x L Step 2.1, denoted as (t), The denoising is performed by wavelet transform on the intrinsic mode functions of the high frequency components obtained by the decomposition, and the meaningful signals in the high frequency components are retained. The denoised signal is denoted as x H (t) is obtained as step 2.2, Reconstructed signal x′(t)=x L (t)+x H Step 2.3 to (t) The method includes step 2.4 of performing noise removal using a wavelet transform on the reconstructed signal x'(t) to further remove noise components contained in the signal to obtain the final signal, and detecting signal singularities to obtain the exact time at which the signal suddenly changes.

[0011] The noise reduction method using wavelet transform is modulo maximum noise reduction.

[0012] Step 3: Based on the exact time when the signal suddenly changes calculated in step 2, initial location is performed within the fault section between the detection node k-1 and the detection node k determined in step 1; Step 3.1 The fault occurrence time is recorded as t0, and the time when the traveling wave signal generated at the fault location F reaches the detection node k-1 and the detection node k is recorded as t k-1,1 and t k,1 The time it takes for a traveling wave signal generated at the fault location to be reflected by the detection node k-1 and the detection node k, pass through the fault location, and be refracted to the other side detection node k and the detection node k-1 is t k,2 and t k-1,2 The time it takes for a traveling wave signal generated at the fault position to be reflected by the detection node k-1 and the detection node k, pass through the fault position, and be reflected again to the detection node k-1 and the detection node k is t k-1,3 and t k,3 and JPEG2025076228000003.jpg154150JPEG2025076228000004.jpg54150JPEG2025076228000005.jpg123150

[0013] In a second aspect, the present invention provides an apparatus for intelligent diagnosis of a high side fault in a power distribution transformer, the apparatus comprising: a memory and a processor; The memory is adapted to store one or more computer instructions that, when executed by the processor, perform the steps of the method.

[0014] In a third aspect, the present invention provides a computer readable storage medium having stored thereon computer instructions which, when executed by a processor, effectuate the steps of the above method.

[0015] In a fourth aspect, a computer program product includes computer programs / instructions which, when executed by a processor, implement the steps of the above method. Effect of the Invention

[0016] The technical solution of the present invention can achieve the following beneficial effects:

[0017] First, the present application first identifies the faulty phase based on phase voltage information to determine the faulty section, and then performs initial location and precise location within the faulty section based on the transient traveling wave signal, gradually approximating the range of fault locations from large to small. By utilizing the advantages of each step of faulty section location, initial location and precise location, the amount of calculation work is greatly reduced, location efficiency is improved and precise location is realized.

[0018] Secondly, the present application uses phase voltage information when a single-phase open-circuit ungrounded fault occurs to identify the faulty phase and determine the fault section. This method can utilize the existing power grid automation system platform or fault indicator system, does not require the deployment of new equipment, and can be realized by simply adding one software module to the main station, with low investment cost and good applicability.

[0019] Third, the present application simultaneously uses stable parameters and transient parameters in combination with the characteristics of phase voltage and transient traveling wave signal at different stages of fault location, respectively, to realize the fusion of physical parameters, fully bring out the physical characteristics of the obtainable parameters, greatly improve the comprehensiveness of the connotation of physical parameter expression, and improve the accuracy of fault location.

[0020] Fourth, the present application adds white Gaussian noise and decomposes it into various criteria components, thereby reducing the impact of adding white Gaussian noise on the signal to be decomposed, effectively denoising the collected fault transient traveling wave signal, retaining the useful signal components in the high-frequency noise components as much as possible, and finally suppressing the distortion of the reconstructed signal as much as possible.

[0021] Fifth, this application processes the collected fault transient traveling wave signal by the optimized adaptive noise complete set empirical mode decomposition method, effectively avoiding the error of the final decomposition result caused by the mode mixing phenomenon in the empirical mode decomposition method, and ensuring the authenticity of the data meaning.

[0022] Sixth, the present application performs denoising by wavelet transform on the intrinsic mode function of the high-frequency components obtained by extraction and decomposition to obtain the meaningful signal components therein, and then reconstructs it together with the low-frequency meaningful signal obtained by adaptive noise complete set empirical mode decomposition, and finally performs denoising by wavelet transform on the reconstructed signal to obtain the final meaningful signal, and finally obtains the specific location of the fault occurrence point by detecting the signal singularity, which not only can reduce the distortion between the final reconstructed signal and the original signal, but also improves the signal filtering effect, and can more accurately obtain the time of the sudden change point of the signal when detecting the signal singularity, thereby improving the location accuracy of single-phase open-circuit non-grounded faults.

[0023] Seventh, by modifying the propagation speed of the traveling wave, the present application effectively overcomes the problems of inaccurate location caused by clock asynchrony and wave speed instability in the traditional traveling wave method, and has higher fault location accuracy without being affected by the line length and fault location. [Brief description of the drawings]

[0024] In order to more clearly explain the technical solutions of the embodiments of the present invention, the following briefly describes the drawings necessary for describing the embodiments. Obviously, the drawings described below are merely examples of the embodiments of the present invention, and those skilled in the art can further obtain other drawings based on these drawings without any creative efforts.

[0025] [Figure 1] FIG. 1 is a schematic diagram showing steps of a method for locating a single-phase open, non-grounded fault in an electrical grid; [Diagram 2] FIG. 1 is a schematic diagram showing the location of a single-phase open-circuit non-grounded fault in an electrical grid; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application, obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. In general, the components of the embodiments of the present application described and shown in the drawings herein may be arranged and designed in various different configurations.

[0027] Therefore, the detailed description of the embodiments of the present application in the following drawings is not intended to limit the scope of the claimed application, but merely illustrates selected embodiments of the present application. Based on the embodiments of the present application, any other embodiments that a person skilled in the art can obtain without creative labor will fall within the scope of protection of the present application.

[0028] It should be noted that like numbers and letters indicate like elements in the following figures, and thus, if an element is defined in one figure, it need not be further defined and interpreted in subsequent figures.

[0029] It is noted that the term "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion, whereby a process, method, article, or apparatus that comprises a set of elements not only includes those elements, but also includes other elements not expressly listed, or includes elements inherent in such process, method, article, or apparatus. Unless otherwise limited, an element limited by the phrase "comprises..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0030] Some embodiments of the present application are described in detail below with reference to the drawings. Unless inconsistent, the following examples and features of the examples may be combined with each other. EXAMPLES

[0031] Referring to FIG. 1-FIG. 2, the present embodiment provides a method for locating a single-phase open-circuit ungrounded fault in a power distribution network, which includes the following steps 1-4.

[0032] Step 1: Obtain phase voltage information to identify the faulty phase and determine the fault section; Phase voltage information is collected from the feeder terminal (FTU) or fault indicator (FI), Step 1.1 Collect phase voltages and mark the detection nodes, mark the detection node at the bus exit as detection node 1, mark the adjacent detection node as detection node 2, and mark the remaining detection nodes one by one in this analogy, and mark the last detection node as detection node n; Step 1.2: Let the detection node 1 be k, where k=1, Step 1.5: If any one of the above three conditions is satisfied, determine that the fault section is the section between detection node k and detection node k-1, and end the determination. Otherwise, let k=k+1, If k≦n, continue to execute step 1.3; If k>n, it is determined that the faulty section is directly the section from the detection node n to the end of the line, and the determination is terminated.

[0033] Step 2 Add white Gaussian noise to the fault transient traveling wave signal by adaptive noise complete ensemble empirical mode decomposition method to obtain the exact time when the signal suddenly changes; Specifically, White Gaussian noise is added to the collected fault transient traveling wave signal to obtain the signal x(t) to be decomposed, and then adaptive noise complete ensemble empirical mode decomposition is performed on the signal x(t) to be decomposed to obtain the intrinsic mode functions of multiple intrinsic mode components, from which the low-frequency meaningful signals are extracted to obtain x L Step 2.1, denoted as (t), The denoising is performed by wavelet transform on the intrinsic mode functions of the high frequency components obtained by the decomposition, and the meaningful signals in the high frequency components are retained. The denoised signal is denoted as x H (t) is obtained as step 2.2, Reconstructed signal x′(t)=x L (t)+x H Step 2.3 to (t) The method includes step 2.4 of performing noise removal using a wavelet transform on the reconstructed signal x'(t) to further remove noise components contained in the signal to obtain the final signal, and detecting signal singularities to obtain the exact time at which the signal suddenly changes.

[0034] Among them, the noise removal method using wavelet transform is the modulo maximum noise removal method.

[0035] Since the lines in a power distribution network are easily affected by various factors such as the environment, when a single-phase open-circuit ungrounded fault occurs, a noise signal is generated when the wavefront of the fault transient traveling wave generated at the fault point reaches the receiving side. The noise signal has a serious impact on the detection and location accuracy of the fault. Therefore, it is necessary to perform noise removal processing on the received fault transient traveling wave signal to extract the truly useful signal, which is the key to accurately locating the fault point.

[0036] The collected fault transient traveling wave signals are analyzed, among which the high frequency part essentially belongs to noise signals, and there are almost no useful signals in the high frequency part, while the low frequency component part contains a large number of useful signals and a small number of noise signals; and the wavelet transform can clearly display the sudden change situation of the signal in the time / frequency domain, and can realize the denoising of the signal, and has the characteristics of having multi-criteria analysis, which is very effective in extracting useful signals from the collected fault transient traveling wave signals. However, the wavelet transform needs to manually select the wavelet base before analyzing the signal, which will have a certain impact on the analysis of the signal. And when a relatively small decomposition criterion is used, the smoothing area of ​​the function obtained by the wavelet transform will also be correspondingly small, and at this time, the closer the modulo maximum point is to the sudden change point of the signal, the greater the impact of noise on the wavelet transform analysis; therefore, a suitable decomposition criterion can be selected according to different needs to obtain a smooth and clear curve. And when the used criterion is relatively large, the smoothed area of ​​the obtained function is correspondingly larger, and at this time, the modulo maximum point is more stable, but in this case, the smoothing action will move the modulo maximum point away from the sudden change point of the signal. Therefore, it is necessary to use the wavelet transform to remove noise by modulo maximum, and to carry out multi-criteria analysis and processing when analyzing and determining the sudden change point of the signal.

[0037] And the empirical mode decomposition method has advantages such as no need to select basis functions and self-adaptability, which avoids the influence of errors caused by manually selecting basis functions on the analysis processing of signals. The empirical mode decomposition method can not only effectively extract the feature information of the original signal, but also decompose it into intrinsic mode function components at different frequency components, so that the reconstruction result is more accurate and reliable. However, when the signal is analyzed and processed by the empirical mode decomposition method, a high-frequency signal with a small amplitude is generated in the signal decomposition process, so that the extreme value changes suddenly, and the mode mixing phenomenon occurs. The mode mixing phenomenon appears as a single intrinsic mode function contains the time base of different features, or the time base of similar features appears between different intrinsic mode functions, so that the waveforms of two similar intrinsic mode functions are mixed with each other and affect each other, making them difficult to distinguish. This not only affects the identification accuracy of the mode parameters, but also greatly reduces the identification accuracy of the system. When the mode mixing phenomenon occurs, it will have a negative effect on the results obtained by empirical mode decomposition, and the signals generated by empirical mode decomposition will lose their physical meaning, and the results obtained will lose their authenticity and validity, resulting in relatively large errors. To solve this problem, measures such as noise removal or reconstruction are generally used, but these measures all have certain limitations.

[0038] The original signal is denoised by wavelet decomposition and the adaptive threshold method is selected, which has a certain filtering effect on the signal, but the filtered signal still contains more noise interference components. When the number of wavelet decomposition layers is increased, more noise signals are filtered, but the original signal is distorted significantly, which seriously affects the fault location accuracy, and the fault cannot be located accurately.

[0039] The high-frequency components after adaptive noise complete-set empirical mode decomposition in the original noisy signal also contain some useful signals, and if the original signal is filtered only by adaptive noise complete-set empirical mode decomposition, the useful signal parts in the high-frequency components will be discarded, causing errors between the final decomposition result and the original signal.

[0040] Step 3: Based on the exact time when the signal suddenly changes calculated in step 2, initial location is performed within the fault section between the detection node k-1 and the detection node k determined in step 1; Step 3.1 The fault occurrence time is recorded as t0, and the time when the traveling wave signal generated at the fault location F reaches the detection node k-1 and the detection node k is recorded as t k-1,1 and t k,1 The time it takes for a traveling wave signal generated at the fault location to be reflected by the detection node k-1 and the detection node k, pass through the fault location, and be refracted to the other side detection node k and the detection node k-1 is t k,2 and t k-1,2 The time it takes for a traveling wave signal generated at the fault position to be reflected by the detection node k-1 and the detection node k, pass through the fault position, and be reflected again to the detection node k-1 and the detection node k is t k-1,3 and t k,3 and JPEG2025076228000007.jpg184150JPEG2025076228000008.jpg132150

[0041] The fault location method of the present application is verified by MATLAB (registered trademark) software, and the identification rate of the fault phase is 91%, the accuracy of the fault section is 89%, the error rate of the initial location is within 9.7%, and the error rate of accurate location is within 6.4%, which verifies the effectiveness of processing the fault transient traveling wave signal by combining the adaptive noise complete set empirical mode decomposition method with the wavelet transform method.

[0042] As can be seen from the above analysis, the present application first identifies the faulty phase and determines the faulty section based on the phase voltage information, and then performs initial location and precise location within the faulty section based on the transient traveling wave signal, gradually approximating the range of the fault location from large to small, and utilizing the advantages of each step of faulty section location, initial location and precise location, greatly reduces the amount of calculation work, improves location efficiency and realizes precise location. When a single-phase open-circuit non-grounded fault occurs, the phase voltage information is used to identify the faulty phase and determine the faulty section. This method can utilize the existing power distribution automation system platform or fault indicator system, and does not require the deployment of new equipment, and can be realized by only adding one software module to the main station, with low investment cost and good applicability.

[0043] The present application simultaneously uses stable parameters and transient parameters, and combines them with the characteristics of phase voltage and transient traveling wave signal for different stages of fault location, respectively, to realize the fusion of physical parameters, fully bring out the physical characteristics of the obtainable parameters, greatly improve the comprehensiveness of the connotation of physical parameter expression, and improve the accuracy of fault location; the present application adds white Gaussian noise and decomposes it into various reference components, thereby reducing the impact of adding white Gaussian noise on the signal to be decomposed, effectively denoising the collected fault transient traveling wave signal, retaining the useful signal components in the high frequency noise components as much as possible, and suppressing the distortion of the final reconstructed signal as much as possible; the present application processes the collected fault transient traveling wave signal by the optimized adaptive noise complete set empirical mode decomposition method, effectively avoiding the error of the final decomposition result caused by the mode mixing phenomenon in the empirical mode decomposition method, and ensuring the authenticity of the meaning of the data.

[0044] In this application, the intrinsic mode function of the high frequency components obtained by extraction and decomposition is denoised by wavelet transform to obtain the meaningful signal components therein, and then reconstructed together with the low frequency meaningful signal obtained by adaptive noise complete set empirical mode decomposition. Finally, the reconstructed signal is denoised by wavelet transform to obtain the final meaningful signal, and finally, the specific location of the fault occurrence point is obtained by detecting the signal singularity. This not only reduces the distortion between the final reconstructed signal and the original signal, but also improves the signal filtering effect, and can more accurately obtain the time of the sudden change point of the signal when detecting the signal singularity, thereby improving the location accuracy of the single phase open circuit non-grounding fault.

[0045] By modifying the propagation speed of the traveling wave, the present application effectively overcomes the problems of inaccurate location caused by clock asynchrony and wave speed instability in the traditional traveling wave method, and has higher fault location accuracy without being affected by the line length and fault location. EXAMPLES

[0046] An embodiment of the present application provides an apparatus for locating a single phase open non-ground fault in an electrical grid, comprising: a memory for storing one or more computer instructions; and a processor, the one or more computer instructions, when executed by the processor, realizing a method according to any one of the first aspects above.

[0047] The node device further includes a communication interface, and the memory, the processor, and the communication interface are electrically connected to each other directly or indirectly to realize data transmission or exchange. For example, these elements can be electrically connected to each other via one or more communication buses or signal lines. The memory may be for storing software programs and modules, and the processor executes the software programs and modules stored in the memory to perform various functional applications and data processing. The communication interface may be for communicating signaling or data with other node devices.

[0048] The memory may be, but is not limited to, a Random Access Memory (RAM), a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Programmable Read-Only Memory (EPROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), and the like.

[0049] The processor may be an integrated circuit chip having signal processing capabilities, which may be a general-purpose processor including a central processing unit (CPU), a network processor (NP), etc., a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component.

[0050] In the embodiments of the present application, it should be understood that the disclosed method and system may be implemented in other ways. The above-described embodiments of the method and system are merely schematic, and for example, the flowcharts and block diagrams in the drawings show possible system architectures, functions and operations of the method and system, the method and computer program product of the embodiments of the present application. In this regard, each block in the flowchart or block diagram may represent a module, a program segment or a part of code, which includes one or more executable instructions for implementing a specified logical function. It should be noted that in some alternative implementations, the functions shown in the blocks may occur in a different order from the order shown in the drawings. For example, two consecutive blocks may actually be executed essentially simultaneously, or may be executed in the reverse order, which is determined by the functions involved. It should be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts may be implemented by a dedicated hardware-based system that executes the specified functions or operations, or by a combination of dedicated hardware and computer instructions. EXAMPLES

[0051] An embodiment of the present application provides a computer-readable storage medium, which stores computer instructions and, when the computer program is executed by a processor, realizes the method according to any one of the first aspects. When the functions are realized in the form of a software functional module and sold or used as an independent product, they may be stored in one computer-readable storage medium. Based on this understanding, the essential or prior art contribution of the technical solution of the present application, or a part of the technical solution, may be embodied in the form of a software product, and the computer software product is stored in one storage medium including some instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or some steps of the method according to each embodiment of the present application. And the storage medium includes various media capable of storing program code, such as a USB memory, a portable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0052] The above description is only a preferred embodiment of the present application, and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

[0053] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application may be realized in other specific ways without departing from the spirit or essential characteristics of the present application. Therefore, in all respects, the embodiments should be considered as illustrative and not restrictive, and the scope of the present application is limited by the appended claims, not the above description, and therefore, it is intended to include in the present application all changes that come within the meaning and range of equivalence of the claims. Any drawing symbols in the claims should not be considered as limiting the relevant claims.

Claims

1. 1. A method for locating a single-phase open, non-grounded fault in an electric power distribution network, comprising: Step 1 of acquiring phase voltage information at the time of fault occurrence to identify a faulty phase and determine a faulty section; Step 2: adding white Gaussian noise to the fault transient traveling wave signal to obtain the exact time when the signal suddenly changes through adaptive noise complete ensemble empirical mode decomposition method; step 3 of initially locating the fault within the fault section determined in step 1 based on the exact time of the sudden change in the signal calculated in step 2; Fault occurrence time t ０ and step 4 of calculating the propagation velocity V′ of the traveling wave to accurately locate the fault location within the initially located range determined in step 3, and step 2 specifically includes: White Gaussian noise is added to the collected fault transient traveling wave signal to obtain the signal x(t) to be decomposed, and then adaptive noise complete set empirical mode decomposition is performed on the signal x(t) to be decomposed to obtain the eigenmode functions of multiple eigenmode components, and the low-frequency meaningful signals therein are extracted to obtain x Ｌ Step 2.1, denoted as (t), The denoising is performed by wavelet transform on the intrinsic mode function of the high frequency components obtained by the decomposition, and the meaningful signal in the high frequency components is retained, and the denoised signal is denoted as x Ｈ Step 2.2, obtaining the Reconstructed signal x'(t)=x Ｌ (t) + x Ｈ Step 2.3 to make (t) and step 2.4 of performing noise removal using a wavelet transform on the reconstructed signal x'(t) to further remove noise components contained in the signal to obtain a final signal, and detecting the signal singularity to obtain the exact time when the signal suddenly changed.

2. Step 1 of acquiring phase voltage information at the time of fault occurrence to identify the faulty phase and determine the faulty section is specifically as follows: Step 1.1: collecting phase voltages and marking detection nodes, marking the detection node at the bus exit as detection node 1, marking the adjacent detection node as detection node 2, and marking the remaining detection nodes one by one in this analogy, and marking the last detection node as detection node n; Step 1.2, where k is the detection node 1 and k=1; If any one of the above three conditions is satisfied, it is determined that the fault section is the section between detection node k and detection node k−1, and the determination is terminated; otherwise, set k=k+1, and if k≦n, continue to execute step 1.

3.

3. The method for locating a single-phase open-circuit non-grounded fault in a power distribution network as described in claim 2, characterized in that the step 1 of obtaining phase voltage information at the time of fault occurrence to identify the faulty phase and determine the faulty section specifically further includes: if k>n, directly determining that the faulty section is the section from the detection node n to the end of the line, and terminating the judgment.

4. Specifically, step 3 of initially locating a fault location includes the following steps: The time when the failure occurs is t ０ and the time when the traveling wave signal generated at the fault location F reaches the detection node k−1 and the detection node k is denoted as t ｋ－１，１ and t ｋ，１ The time when the traveling wave signal generated at the fault position is reflected by the detection node k-1 and the detection node k, passes through the fault position, and is refracted to the detection node k and the detection node k-1 on the other side is t ｋ，２ and t ｋ－１，２ The time it takes for a traveling wave signal generated at the fault location to be reflected by the detection nodes k-1 and k, pass through the fault location, and be reflected again by the detection nodes k-1 and k is t ｋ－１，３ and t ｋ，３ Step 3.1, where Calculate the distance between the fault location F and the detection node k-1; Assuming that the distance between detection node k−1 and detection node k is L and the propagation speed of the traveling wave is V, L=V×(t ｋ－１，１ +t ｋ，１ -2t 0 ) and The method for locating a single-phase open, non-grounded fault in a power distribution network according to claim 3, further comprising:

5. Step 4 of accurately locating the fault location is specifically as follows: The method for locating a single-phase open-circuit, non-grounded fault in a power distribution network according to claim 4.

6. The method for locating a single-phase open-not-grounded fault in a power distribution network according to claim 1, characterized in that the phase voltage information in step 1 is obtained from a feeder terminal (FTU) or a fault indicator (FI).

7. The method for locating a single-phase open-circuit non-grounded fault in a power distribution network according to claim 1, characterized in that the denoising by wavelet transform uses modulo maximum denoising.

8. 1. An apparatus for locating a single phase open, non-ground fault in an electrical grid comprising a memory and a processor, The memory is for storing one or more computer instructions, and the one or more computer instructions are executed by the processor to realize the steps of the method for locating a single-phase open, non-grounded fault in a power distribution network described in claims 1 to 7. A device for locating a single-phase open, non-grounded fault in a power distribution network.

9. A computer-readable storage medium having computer instructions stored thereon, comprising: A computer readable storage medium which, when executed by a processor, implements the steps of the method for locating a single phase open, non-ground fault in an electrical grid according to claims 1-7.

10. 1. A computer program product comprising: A computer program product comprising computer programs / instructions, which, when executed by a processor, implement the steps of the method for locating single-phase-open, non-ground faults in an electrical grid according to claims 1-7.

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