Transmission line development fault identification method and system based on Clarke transform

Abstract

The present invention discloses a method and system for identifying transmission line developmental faults based on Clarke transform, comprising: determining the initial fault type based on the amplitude mutation amount in the fundamental frequency signal of the normal operating state and the initial fault state of the transmission line extracted by Fourier transform; determining a special phase based on the initial fault type, determining the phase data input order of the three-phase current signal in the Clarke transform based on the special phase, and performing Clarke transform to obtain the line mode component and zero mode component of the normal operating state, the initial fault state and after the initial fault, and judging the developmental fault type that the initial fault type will evolve into by comparing the amplitude changes of the line mode component and the zero mode component respectively. By comparing the amplitude changes of the line mode component and the zero mode component in normal operation, initial fault and after the initial fault, the present invention can quickly and accurately judge what type of fault the initial fault will develop into, thereby improving the accuracy of relay protection and fault phase selection.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system relay protection, and in particular relates to a method and system for identifying transmission line developmental faults based on Clarke transformation. Background Art

[0002] Transmission lines are exposed to the atmosphere for long periods of time and are susceptible to failures caused by lightning strikes, strong winds, foreign objects, dirt, ice, and other factors. If faults on transmission lines cannot be promptly removed and remain in abnormal operation for a long time, they can lead to more serious failures and even cause large-scale power outages.

[0003] A developing fault occurs when the same fault point expands or transforms due to the amplification or transformation of the triggering factor, leading to the fault progressing from a single-phase fault to an interphase or even three-phase fault. Although the probability of a developing fault is much lower than that of a single fault, the damage to the power system is far greater than that of a single fault. If a developing fault is not promptly and correctly eliminated, it can cause phase selectors to misselect phases and protective devices to malfunction, resulting in secondary impacts to the power grid. Therefore, timely and accurate identification of developing faults and the implementation of appropriate measures can prevent further expansion and improve the operational stability of the power system.

[0004] Currently, there are few methods for identifying developing faults on transmission lines. Traditional methods primarily rely on the difference or ratio between the post-fault voltage and current sequence components, manually selecting appropriate thresholds as fault criteria. However, issues such as asymmetric three-phase parameters and inappropriate threshold selection can significantly impact the effectiveness of these methods. Artificial intelligence algorithms combined with deep learning require extensive training datasets, which is incompatible with the limited number of developing fault samples. In summary, there is currently a lack of methods that can accurately, reliably, and rapidly identify developing faults. Summary of the Invention

[0005] Based on the above technical problems, the purpose of the present invention is to provide a method and system for identifying transmission line developmental faults based on Clarke transform. By comparing the amplitude changes of the line mode component and the zero mode component during normal operation, initial fault and after the initial fault, it can quickly and reliably determine whether a developmental fault has occurred and the developmental fault that the initial fault will evolve into, thereby solving the problem of incorrect phase selection caused by transmission line developmental faults.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention discloses a method for identifying transmission line developmental faults based on Clarke transform, comprising the following steps:

[0008] S1, real-time acquisition of three-phase current signals of the transmission line, including three-phase current signals in normal operating state, three-phase current signals in initial fault state, and three-phase current signals after initial fault;

[0009] S2, based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, respectively obtain the fundamental frequency signal of the three-phase current signal in the normal operating state and the fundamental frequency signal of the three-phase current signal in the initial fault state through fast Fourier transform, and then determine the initial fault type of the faulty transmission line based on the amplitude change of the fundamental frequency signal in the normal operating state and the initial fault state; S3, determine the special phase based on the characteristic information of the determined initial fault type, and determine the phase data input order of the three-phase current signal in Clarke transform based on the determined special phase;

[0010] S4, based on the phase data input order determined in step S3, performing Clarke transform on the three-phase current signal in the normal operating state, the three-phase current signal in the initial fault state, and the three-phase current signal after the initial fault, to obtain line mode components and zero mode components in the normal operating state, the initial fault state, and after the initial fault, respectively;

[0011] S5, based on the initial fault type, compare the amplitudes of the line mode component and zero mode component obtained after the initial fault with the line mode component and zero mode component of the normal operating state or the initial fault state, to determine whether a developmental fault occurs and the developmental fault type that the initial fault type will evolve into.

[0012] Based on the above disclosed steps, the present invention determines the special phase of the initial fault and adjusts the input order of the three-phase current signal of the transmission line in the Clarke transform based on the special phase, thereby effectively obtaining the line mode component and zero mode component in the normal operating state, the initial fault state and the initial fault state based on the characteristic information of the specific initial fault, and then by comparing the obtained line mode component and zero mode component after the initial fault with the amplitude of the line mode component and zero mode component in the normal operating state or the line mode component and zero mode component in the initial fault state, it is possible to efficiently and accurately judge the developmental fault that the initial fault will evolve into, that is, based on the initial fault, it is possible to know in advance what kind of more serious fault the initial fault will develop into, thereby greatly improving the accuracy of relay protection and fault phase selection.

[0013] In step S1 of the present invention, the three-phase current signal of the transmission line is obtained in real time, specifically, at a sampling rate of f s The three-phase current signal is extracted under s Indicates the number of times the three-phase current signal is collected per unit time. Among them, the higher sampling rate f sIt is possible to capture the transient changes of the three-phase current more quickly, so that the mutation information of the three-phase current can be captured in time when and after a fault occurs, thereby facilitating the rapid positioning of the time and location of the fault. Moreover, since the three-phase current signal is acquired in real time, not only can the initial fault (i.e., the type of fault that is occurring) be discovered in real time and its type be judged, but also whether a developmental fault has occurred and the type of the developmental fault can be judged after the initial fault. In other words, based on the method of the present invention, the initial fault and the developmental fault can be judged in real time and continuously, thereby eliminating the need to adopt different and incoherent methods to judge the initial fault and the developmental fault separately as in the prior art.

[0014] It should be emphasized that the so-called "after the initial fault" is relative to the state when the initial fault occurs, that is, a certain moment or a certain period of time after the initial fault occurs. Based on the aforementioned sampling rate, the three-phase current signal after the initial fault can be s Any sampling rate f after obtaining the three-phase current of the initial fault state s The three-phase current signal.

[0015] In step S2, the three-phase current signals of the normal operating state and the initial fault state are converted from the time domain to the frequency domain through fast Fourier transform. When a sudden change occurs in the three-phase current signal, the fault characteristics can be more prominent, which facilitates the analysis of the initial fault type and allows for a quick judgment.

[0016] In step S3, when the initial fault type is a single-phase grounding fault, the special phase is determined to be the phase where the fault occurs; when the initial fault is a two-phase grounding fault or a two-phase short circuit fault, the special phase is determined to be a healthy phase, where the healthy phase refers to the phase where no fault occurs.

[0017] In a specific embodiment, the initial fault type is phase A grounded and phase BC short-circuited. When phase BC is grounded, the special phase is determined to be phase A; the initial fault type is phase B grounded and phase CA short-circuited. When phase CA is grounded, the special phase is determined to be phase B; the initial fault type is phase C grounded and phase AB short-circuited. When phase AB is grounded, the special phase is determined to be phase C. See Table 1 below for details.

[0018] Table 1 Determination of special phases for developing faults

[0019]

[0020] Further, in step S3, the phase data input order of the three-phase current signal in the Clarke transform is determined based on the determined special phase, including: when the special phase is phase A, the phase data input order of the three-phase current signal in the Clarke transform is determined to be When the special phase is phase B, the order of inputting the phase data of the three-phase current signal in the Clarke transform is: When the special phase is phase C, the order of inputting the phase data of the three-phase current signal in the Clarke transform is:

[0021] In the present invention, the three-phase current signal is Clarke transformed into line mode components and zero mode components. The Clarke transformation matrix is as follows:

[0022]

[0023] That is, when the special phase is phase A, the Clarke transform corresponding to the three-phase current signal is as follows:

[0024]

[0025] When the special phase is phase B, the Clarke transform corresponding to the three-phase current signal is as follows:

[0026]

[0027] When the special phase is phase C, the Clarke transform corresponding to the three-phase current signal is as follows:

[0028]

[0029] By performing Clarke transform on the three-phase current signal, the line mode component and zero mode component in the normal operating state, the initial fault state, and the state after the initial fault can be obtained respectively.

[0030] In the present invention, the three-phase current signal input by Clarke transformation is is the current phasor, including amplitude and phase, and the line mode component is obtained after Clarke transformation and zero mode component The amplitude indicates the size. The three-phase current signal at each time point After Clarke transform, the line mode component is obtained and zero mode component Line mode component and zero mode component With three-phase current signal There is a continuous one-to-one correspondence on the time axis.

[0031] In the present invention, the amplitudes of the line mode components in the normal operating state are defined as Amplitude of the zero mode component The amplitudes of the line mode components of the initial fault state are Amplitude of the zero mode component The amplitudes of the line mode components after the initial fault are Amplitude of the zero mode component The above linear modulus amplitude and the amplitude of the zero mode component The special phase determined by the initial fault determines the phase data input order of the three-phase current signal in the Clarke transformation and then performs Clarke transformation.

[0032] Furthermore, in step S5, based on the initial fault type, the amplitude of the line mode component and the zero mode component after the initial fault is compared with the line mode component and the zero mode component in the normal operation state or the initial fault state, so as to judge whether a fault has occurred and the type of developing fault that the initial fault type will evolve into based on the amplitude change after the comparison, including: when the initial fault type is a single-phase grounding fault, the amplitude of the β mode component after the initial fault is compared with the amplitude of the line mode component and the zero mode component in the normal operation state or the initial fault state. The amplitude of the β-mode component of the initial fault state Compare and based on and The amplitude change after comparison is used to judge whether a single-phase grounding fault will evolve into a developing fault; when the initial fault type is a two-phase grounding fault, the amplitude of the zero-mode component after the initial fault is The amplitude of the zero mode component of the initial fault state Compare and based on and The amplitude change after comparison is used to judge whether a single-phase grounding fault will evolve into a developing fault; when the initial fault type is a two-phase phase-to-phase fault, the amplitude of the zero-mode component after the initial fault is The amplitude of the zero mode component of the initial fault state Compare or compare the amplitude of the α mode component after the initial fault The amplitude of the α-mode component in normal operation Compare and based on and Amplitude change after comparison or and The amplitude changes after comparison are used to determine whether the two-phase fault will evolve into a developing fault.

[0033] In a preferred embodiment, the step of determining the type of developing fault includes: when the single-phase grounding fault is A-phase grounding, When the A phase grounding fault is about to evolve into the AB phase grounding fault, the A phase grounding fault will be judged as the AB phase grounding fault. When the A phase grounding fault is about to evolve into the CA phase grounding fault, the single-phase grounding fault is the B phase grounding fault. When the B phase grounding fault is about to evolve into the AB phase grounding fault, the single-phase grounding fault is the B phase grounding fault. When the B phase grounding fault is about to evolve into the BC phase grounding fault, the single-phase grounding fault is the C phase grounding fault. When the C phase grounding fault is about to evolve into the CA phase grounding fault, the single-phase grounding fault is the C phase grounding fault. When the C phase grounding is about to evolve into the BC phase grounding; the two-phase grounding fault is the AB phase grounding. When the AB phase grounding is about to evolve into the ABC phase grounding; the two-phase grounding fault is the BC phase grounding. When the BC phase grounding fault is about to evolve into the ABC phase grounding fault, the two-phase grounding fault is the CA phase grounding fault. When the phase-to-phase fault is between AB and CA, it is judged that the phase-to-phase fault will evolve into the phase-to-phase fault between AB and CA. When the AB phase is about to turn into AB phase grounding; the two-phase fault is between BC phases, when When the BC phase is about to turn into BC phase grounding; the two-phase fault is between CA phases. When the phase-to-phase fault is between AB phases, it is judged that the phase-to-phase fault will evolve into the phase-to-phase fault between CA phases. When the AB phase is about to evolve into the ABC phase; the two-phase fault is the BC phase. When the BC phase is about to evolve into the ABC phase; the two-phase fault is the CA phase. When , it is judged that the CA phase will evolve into the ABC phase, as shown in Table 2 below. Among them, k1, k2, k3, k4 and k5 are proportional coefficients.

[0034] Table 2 Developmental fault judgment basis

[0035]

[0036]

[0037] In the transmission line developmental fault identification method based on Clarke transform disclosed according to the first aspect of the present invention, the value range of k1 is 1.1-1.3, the value range of k2 is 0.8-0.9, the value range of k3 is 0.7-0.9, the value range of k4 is 1.2-1.5, and the value range of k5 is 1.1-1.4.

[0038] The second aspect of the present invention discloses a transmission line development fault identification system based on Clarke transform, comprising:

[0039] A three-phase current signal acquisition unit is configured to acquire three-phase current signals of the transmission line in real time, including three-phase current signals in a normal operating state, three-phase current signals in an initial fault state, and three-phase current signals after an initial fault;

[0040] an initial fault type determination unit, configured to, based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, obtain a fundamental frequency signal of the three-phase current signal in the normal operating state and a fundamental frequency signal of the three-phase current signal in the initial fault state by fast Fourier transform, and then determine the initial fault type of the faulty transmission line based on amplitude changes of the fundamental frequency signals in the normal operating state and the initial fault state;

[0041] a special phase determining unit configured to determine the special phase based on the characteristic information of the determined initial fault type, and determine an input order of phase-specific data of the three-phase current signal in Clarke transform based on the determined special phase;

[0042] a line mode component and zero mode component determining unit, configured to perform Clarke transform on the three-phase current signal in the normal operating state, the three-phase current signal in the initial fault state, and the three-phase current signal after the initial fault, respectively, based on the phase data input sequence determined in step S3, to obtain the line mode component and zero mode component in the normal operating state, the initial fault state, and the post-initial fault state, respectively;

[0043] The developmental fault judgment unit is constructed to compare the amplitudes of the line mode component and zero mode component obtained after the initial fault with the line mode component and zero mode component of the normal operating state or the initial fault state based on the initial fault type, so as to judge whether a developmental fault occurs and the developmental fault type that the initial fault type will evolve into.

[0044] The third aspect of the present invention discloses an electronic device, comprising a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the transmission line developmental fault identification method based on Clarke transform disclosed in the first aspect of the present invention.

[0045] The beneficial effects of the present invention are as follows:

[0046] The present invention innovatively determines the data input sequence of the Clarke transform using a special phase, then performs a Clarke transform based on the determined data sequence to compare the amplitude changes of the line mode component and the zero mode component during normal operation, initial fault, and after the initial fault, allowing for rapid and reliable determination of the developing fault that the initial fault will evolve into. This significantly improves the accuracy of relay protection and fault phase selection, effectively resolving the problem of phase selection components misselecting phases due to developing faults on existing transmission lines. Furthermore, the phase-specific data input sequence of the three-phase current signal in the Clarke transform is determined based on the special phase determined by the initial fault, thereby obtaining comparison parameters of the line mode component and the zero mode component after the developing fault, thereby improving the accuracy of determining the developing fault that the initial fault will evolve into. This allows the present invention to accurately determine which two-phase grounding fault will evolve into if the initial fault is a single-phase grounding fault; accurately determine which three-phase grounding fault will evolve into if the initial fault is a two-phase grounding fault; and accurately determine which phase-to-phase grounding fault will evolve into if the initial fault is a two-phase interphase fault.

[0047] The following discloses in detail the transmission line developmental fault identification method and system based on Clarke transform of the present invention with reference to the embodiments and reference numerals shown in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a step diagram of the method for identifying developmental faults in power transmission lines according to the present invention;

[0049] Figure 2 The three-phase current i is the current when the A-phase grounding fault develops into the AB-phase grounding fault in the present invention. ABC and line mode component i αβ0 picture;

[0050] Figure 3 The single-phase grounding fault of the present invention develops into a two-phase grounding fault Amplitude change graph;

[0051] Figure 4 The two-phase grounding fault of the present invention develops into a three-phase grounding fault Amplitude change graph;

[0052] Figure 5 The two-phase interphase fault of the present invention develops into a two-phase grounding fault Three-phase interphase fault Amplitude change graph;

[0053] Figure 6 The two-phase interphase fault of the present invention develops into a three-phase interphase fault and Waveform comparison chart. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other unless there is a conflict.

[0055] like Figure 1 As shown, the present invention discloses a method for identifying transmission line developmental faults based on Clarke transform, comprising the following steps:

[0056] S1, real-time acquisition of the three-phase current signal of the transmission line, including the three-phase current signal in normal operating state, the three-phase current signal in initial fault state and the three-phase current signal after the initial fault; S2, based on the three-phase current signal in normal operating state and the three-phase current signal in initial fault state, the fundamental frequency signal of the three-phase current signal in normal operating state and the fundamental frequency signal of the three-phase current signal in initial fault state are respectively obtained by fast Fourier transform, and then the initial fault type of the faulty transmission line is determined based on the amplitude change of the fundamental frequency signal in normal operating state and in initial fault state; S3, based on the characteristic information of the determined initial fault type, the special phase is determined, and the Clark phase is determined based on the determined special phase. The phase data input order of the three-phase current signal in the transformation; S4, based on the phase data input order determined in step S3, the three-phase current signal in the normal operating state, the three-phase current signal in the initial fault state and the three-phase current signal after the initial fault are respectively subjected to Clarke transformation to obtain the line mode component and zero mode component in the normal operating state, the initial fault state and after the initial fault respectively; S5, based on the initial fault type, and the amplitude of the obtained line mode component and zero mode component after the initial fault are compared with the line mode component and zero mode component of the normal operating state or the initial fault state, to determine whether a developmental fault occurs and the developmental fault type that the initial fault type will evolve into.

[0057] By comparing the amplitude changes of line mode components during normal operation, initial faults and developing faults, the present invention can accurately and reliably determine the developing fault that the initial fault will evolve into. That is, based on the initial fault, it is known in advance what kind of more serious fault the initial fault will further develop into, thereby improving the accuracy of relay protection and fault phase selection.

[0058] In the embodiment of the present invention, in step S1, at the sampling rate f s The three-phase current signal is extracted under s Indicates the number of times the three-phase current signal is collected per unit time, where the higher sampling rate f sIt can capture the transient changes of three-phase current more quickly, so as to obtain these mutation information in time when a fault occurs, so as to accurately obtain the time and location of the fault. The specific sampling rate f s The size is selected according to the actual situation.

[0059] Furthermore, in step S2, the three-phase current signals in the normal operating state and the three-phase current signals in the initial fault state are converted from the time domain to the frequency domain through fast Fourier transform, which can highlight the fault characteristics and facilitate the analysis of the initial fault type. When a fault occurs, the initial fault type can be quickly determined by analyzing the mutation amount of the fundamental frequency amplitude on the Fourier spectrum. For example, if phase A and phase B are short-circuited, the fundamental frequency current amplitude of these two phases will increase, and the frequency spectrum shows that the fundamental frequency amplitude mutation amount of these two phases is obvious. The current amplitude of phase C remains basically unchanged, so its fundamental frequency amplitude is relatively stable on the spectrum, and this is used as a basis for determining the initial fault.

[0060] In a preferred embodiment, in step S3, the special phase is determined based on the characteristic information of the determined initial fault type, including: when the initial fault type is phase A grounded, phase BC short-circuited, and phase BC grounded, the special phase is determined to be phase A; when the initial fault type is phase B grounded, phase CA short-circuited, and phase CA grounded, the special phase is determined to be phase B; when the initial fault type is phase C grounded, phase AB short-circuited, and phase AB grounded, the special phase is determined to be phase C.

[0061] Further preferably, in step S3, when the special phase is phase A, the order of inputting the phase data of the three-phase current signal in the Clarke transform is determined to be When the special phase is phase B, the order of inputting the phase data of the three-phase current signal in the Clarke transform is: When the special phase is phase C, the order of inputting the phase data of the three-phase current signal in the Clarke transform is:

[0062] In the present invention, the three-phase current signal is Clarke transformed into line mode components and zero mode components. The Clarke transformation matrix is as follows:

[0063]

[0064] That is, when the special phase is phase A, the Clarke transform corresponding to the three-phase current signal is as follows:

[0065]

[0066] When the special phase is phase B, the Clarke transform corresponding to the three-phase current signal is as follows:

[0067]

[0068] When the special phase is phase C, the Clarke transform corresponding to the three-phase current signal is as follows:

[0069]

[0070] By performing Clarke transform on the three-phase current signal, the line mode component and zero mode component in the normal operating state, the initial fault state, and the state after the initial fault can be obtained respectively.

[0071] In the present invention, the amplitudes of the line mode components in the normal operating state are defined as Amplitude of the zero mode component The amplitudes of the line mode components of the initial fault state are Amplitude of the zero mode component The amplitudes of the line mode components after the initial fault are Amplitude of the zero mode component The above linear modulus amplitude and the amplitude of the zero mode component The special phase determined by the initial fault determines the phase data input order of the three-phase current signal in the Clarke transformation and then performs Clarke transformation.

[0072] In the embodiment of the present invention, in step S5, based on the initial fault type, the amplitude of the line mode component and the zero mode component after the initial fault is compared with the line mode component and the zero mode component in the normal operation state or the initial fault state, so as to judge whether a fault has occurred and the type of developmental fault to which the initial fault type will evolve based on the amplitude change after the comparison, including: when the initial fault type is a single-phase grounding fault, the amplitude of the β mode component after the initial fault is compared with the amplitude of the line mode component and the zero mode component in the normal operation state or the initial fault state. The amplitude of the β-mode component of the initial fault state Compare and based on and The amplitude change after comparison is used to judge whether a single-phase grounding fault will evolve into a developing fault; when the initial fault type is a two-phase grounding fault, the amplitude of the zero-mode component after the initial fault is The amplitude of the zero mode component of the initial fault state Compare and based on and The amplitude change after comparison is used to judge whether a single-phase grounding fault will evolve into a developing fault; when the initial fault type is a two-phase phase-to-phase fault, the amplitude of the zero-mode component after the initial fault is The amplitude of the zero mode component of the initial fault state Compare or compare the amplitude of the α mode component after the initial fault The amplitude of the α-mode component in normal operation Compare and based on and Amplitude change after comparison or and The amplitude changes after comparison are used to determine whether the two-phase fault will evolve into a developing fault.

[0073] In a preferred embodiment, the specific judgment basis is: the single-phase grounding fault is A phase grounding, when When the A phase grounding fault is about to evolve into the AB phase grounding fault, the A phase grounding fault will be judged as the AB phase grounding fault. When the A phase grounding fault is about to evolve into the CA phase grounding fault, the single-phase grounding fault is the B phase grounding fault. When the B phase grounding fault is about to evolve into the AB phase grounding fault, the single-phase grounding fault is the B phase grounding fault. When the B phase grounding fault is about to evolve into the BC phase grounding fault, the single-phase grounding fault is the C phase grounding fault. When the C phase grounding fault is about to evolve into the CA phase grounding fault, the single-phase grounding fault is the C phase grounding fault. When the C phase grounding is about to evolve into the BC phase grounding; the two-phase grounding fault is the AB phase grounding. When the AB phase grounding is about to evolve into the ABC phase grounding; the two-phase grounding fault is the BC phase grounding. When the BC phase grounding fault is about to evolve into the ABC phase grounding fault, the two-phase grounding fault is the CA phase grounding fault. When the phase-to-phase fault is between AB and CA, it is judged that the phase-to-phase fault will evolve into the phase-to-phase fault between AB and CA. When the AB phase is about to turn into AB phase grounding; the two-phase fault is between BC phases, when When the BC phase is about to turn into BC phase grounding; the two-phase fault is between CA phases. When the phase-to-phase fault is between AB phases, it is judged that the phase-to-phase fault will evolve into the phase-to-phase fault between CA phases. When the AB phase is about to evolve into the ABC phase; the two-phase fault is the BC phase. When the BC phase is about to evolve into the ABC phase; the two-phase fault is the CA phase. When the CA phase is about to evolve into the ABC phase,

[0074] In the embodiment of the present invention, the value range of k1 is 1.1-1.3, the value range of k2 is 0.8-0.9, the value range of k3 is 0.7-0.9, the value range of k4 is 1.2-1.5, and the value range of k5 is 1.1-1.4.

[0075] Example 1: Single-phase grounding fault develops into two-phase grounding fault

[0076] Figure 2The three-phase current i is the current when the A-phase grounding fault develops into the AB-phase grounding fault in the present invention. ABC and line mode component i αβ0 The figure is divided into three stages: 0-0.067s is stage I normal operation, 0.067-0.1s is stage II A phase grounding fault, and 0.1-0.167s is stage III developing into AB phase grounding fault. Figure 3 The single-phase grounding fault of the present invention develops into a two-phase grounding fault Amplitude change diagram, from Figure 2 and Figure 3 In the data displayed, each stage shows a one-to-one correspondence on the timeline.

[0077] When the initial fault is a phase A ground fault and the special phase is phase A, the data input sequence is: Figure 3 In (a) and (b), it is not difficult to see that in the initial fault stage (i.e., phase A ground fault) The amplitude of has not changed. Figure 3 (a) It can be seen that after the developing fault (i.e., the A phase grounding fault develops into the AB phase grounding fault) The amplitude of the fault decreases compared to the initial fault stage, which meets the criterion set up. Figure 3 The results of other single-phase grounding faults developing into two-phase grounding faults also verified that the judgment basis was correct.

[0078] Example 2: A two-phase grounding fault develops into a three-phase grounding fault

[0079] Figure 4 The two-phase grounding fault of the present invention develops into a three-phase grounding fault Amplitude change diagram, when the initial fault is BC phase grounding fault, the special phase is phase A, the data input order is Depend on Figure 4 (b) It is not difficult to see that in the initial fault stage (i.e. BC phase grounding fault) After a developing fault (i.e., a BC phase-to-ground fault develops into an ABC phase-to-ground fault) The amplitude of is lower than that of the initial fault stage, which is consistent with set up. Figure 4 The result that the remaining two-phase grounding faults developed into three-phase grounding faults also verified that the judgment basis was set correctly.

[0080] Example 3: Two-phase interphase fault develops into two-phase ground fault

[0081] Figure 5 The two-phase interphase fault of the present invention develops into a two-phase grounding fault Three-phase interphase fault Amplitude change diagram, when the initial fault is a BC phase fault, the special phase is phase A, and the data input order is Depend on Figure 5 (c) It is not difficult to see that in the initial fault stage (i.e., BC phase fault) The amplitude of s is slightly fluctuated around 0. After a developing fault (i.e., a BC phase-to-phase fault develops into a BC phase-to-ground fault) The amplitude of the fault is higher than that of the initial fault stage, which is consistent with the criterion set up. Figure 5 The results of the other two-phase faults (a), (c), and (e) developing into two-phase grounding faults also verify that the judgment basis is set correctly.

[0082] Example 4: Two-phase interphase fault develops into three-phase interphase fault

[0083] Figure 6 The two-phase interphase fault of the present invention develops into a three-phase interphase fault and Waveform comparison diagram, when the initial fault is BC phase fault, the special phase is A phase, the data input order is at this time, In case of two-phase fault Substituting into at this time and There is only a change in amplitude, which is consistent with the electrical value before and after the fault and The waveform comparison of Figure 6 As shown. Figure 5 (d) It is not difficult to see that in the initial fault stage (i.e., BC phase fault) Compared with the normal operating state, the amplitude fluctuates slightly. After the development fault (i.e., the BC phase fault develops into the ABC phase fault) The amplitude of the value is greatly increased compared with the normal operating state, which meets the criteria set up. Figure 5 (b), (d), (f) The results of the other two-phase interphase faults developing into three-phase interphase faults also verify that the judgment basis is correct.

[0084] According to the above embodiment, the present invention determines the specific phase through initial fault information, changes the input order of the Clarke transform, and compares and analyzes the amplitude changes of the line mode component and zero mode component during normal operation, initial fault, and after the initial fault to accurately and quickly identify the fault that the initial fault phase develops into when a single-phase grounding fault develops into a two-phase grounding fault, when a two-phase grounding fault develops into a three-phase grounding fault, when a two-phase interphase fault develops into a two-phase grounding fault, and when a two-phase interphase fault develops into a three-phase interphase fault. Theoretical derivation and extensive analysis of results have verified the effectiveness and reliability of the present invention, and this method can be applied to most areas of power system transmission line development fault identification.

[0085] The present invention also discloses a transmission line development fault identification system based on Clarke transform, comprising:

[0086] A three-phase current signal acquisition unit is configured to acquire three-phase current signals of the transmission line in real time, including three-phase current signals in a normal operating state, three-phase current signals in an initial fault state, and three-phase current signals after an initial fault;

[0087] an initial fault type determination unit, configured to, based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, obtain a fundamental frequency signal of the three-phase current signal in the normal operating state and a fundamental frequency signal of the three-phase current signal in the initial fault state by fast Fourier transform, and then determine the initial fault type of the faulty transmission line based on amplitude changes of the fundamental frequency signals in the normal operating state and the initial fault state;

[0088] a special phase determining unit configured to determine the special phase based on the characteristic information of the determined initial fault type, and determine an input order of phase-specific data of the three-phase current signal in Clarke transform based on the determined special phase;

[0089] a line mode component and zero mode component determining unit, configured to perform Clarke transform on the three-phase current signal in the normal operating state, the three-phase current signal in the initial fault state, and the three-phase current signal after the initial fault, respectively, based on the phase data input sequence determined in step S3, to obtain the line mode component and zero mode component in the normal operating state, the initial fault state, and the post-initial fault state, respectively;

[0090] The developmental fault judgment unit is constructed to compare the amplitudes of the line mode component and zero mode component obtained after the initial fault with the line mode component and zero mode component of the normal operating state or the initial fault state based on the initial fault type, so as to judge whether a developmental fault occurs and the developmental fault type that the initial fault type will evolve into.

[0091] The present invention also discloses an electronic device, comprising a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the transmission line developmental fault identification method based on Clarke transform disclosed in the first aspect of the present invention.

[0092] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to the multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0093] In addition, the functional modules in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0094] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0095] The foregoing is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.

[0096] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

[0097] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for identifying transmission line developmental faults based on Clarke transform, characterized in that: The steps include: S1, real-time acquisition of three-phase current signals of the transmission line, including three-phase current signals in normal operating state, three-phase current signals in initial fault state, and three-phase current signals after initial fault; S2, based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, respectively obtain the fundamental frequency signal of the three-phase current signal in the normal operating state and the fundamental frequency signal of the three-phase current signal in the initial fault state through fast Fourier transform, and then determine the initial fault type of the faulty transmission line based on the amplitude change of the fundamental frequency signal in the normal operating state and the initial fault state; S3, determining a special phase based on the characteristic information of the determined initial fault type, and determining an input order of phase data of the three-phase current signal in Clarke transformation based on the determined special phase; S4, based on the phase data input order determined in step S3, performing Clarke transform on the three-phase current signal in the normal operating state, the three-phase current signal in the initial fault state, and the three-phase current signal after the initial fault, to obtain line mode components and zero mode components in the normal operating state, the initial fault state, and after the initial fault, respectively; S5, based on the initial fault type, comparing the amplitudes of the line mode component and zero mode component obtained after the initial fault with the line mode component and zero mode component in the normal operating state or the initial fault state, to determine whether a developing fault has occurred and the developing fault type to which the initial fault type will evolve; In step S3, a special phase is determined based on the characteristic information of the determined initial fault type, including: When the initial fault type is phase A grounded, phase BC short-circuited, and phase BC grounded, the special phase is determined to be phase A; When the initial fault type is phase B grounded, phase CA short-circuited, or phase CA grounded, the special phase is determined to be phase B; When the initial fault type is phase C grounding, phase AB short circuit, and phase AB grounding, the special phase is determined to be phase C.

2. The method for identifying transmission line developmental faults based on Clarke transform according to claim 1, characterized in that: In step S3, the phase data input order of the three-phase current signal in Clarke transformation is determined based on the determined special phase, including: When the special phase is phase A, the order of inputting the phase data of the three-phase current signal in the Clarke transform is: When the special phase is phase B, the order of inputting the phase data of the three-phase current signal in the Clarke transform is: When the special phase is phase C, the order of inputting the phase data of the three-phase current signal in the Clarke transform is:

3. The method for identifying transmission line developmental faults based on Clarke transform according to claim 2, characterized in that: In step S5, the amplitudes of the line mode components in the normal operating state are defined as Amplitude of the zero mode component The amplitudes of the line mode components of the initial fault state are Amplitude of the zero mode component The amplitudes of the line mode components after the initial fault are Amplitude of the zero mode component The steps of comparing the amplitudes of the line mode component and the zero mode component after the initial fault with the line mode component and the zero mode component in the normal operation state or the initial fault state based on the initial fault type, and determining whether a fault has occurred and the type of developing fault that the initial fault type will evolve into based on the amplitude changes after the comparison, include: When the initial fault type is a single-phase grounding fault, the amplitude of the β-mode component after the initial fault is The amplitude of the β-mode component of the initial fault state Compare and based on and The amplitude change after comparison is used to determine whether a single-phase grounding fault will evolve into a developing fault; When the initial fault type is a two-phase grounding fault, the amplitude of the zero-mode component after the initial fault is The amplitude of the zero mode component of the initial fault state Compare and based on and The amplitude change after comparison is used to determine whether a single-phase grounding fault will evolve into a developing fault; When the initial fault type is a two-phase-to-phase fault, the amplitude of the zero-mode component after the initial fault is The amplitude of the zero mode component of the initial fault state For comparison; or the amplitude of the α mode component after the initial fault The amplitude of the α-mode component in normal operation Compare and based on and Amplitude change after comparison or and The amplitude changes after comparison are used to determine whether the two-phase fault will evolve into a developing fault.

4. The method for identifying transmission line developmental faults based on Clarke transform according to claim 3, characterized in that: In step S5, the step of judging the developing fault that the initial fault type will evolve into based on the amplitude change after comparison includes: Single-phase grounding fault is A phase grounding. When the A phase grounding fault is about to evolve into the AB phase grounding fault; Single-phase grounding fault is A phase grounding. When , it is judged that the A phase grounding fault will evolve into the CA phase grounding fault; Single-phase grounding fault is phase B grounding. When , it is judged that the B phase grounding fault will evolve into the AB phase grounding fault; Single-phase grounding fault is phase B grounding. When , it is judged that the B phase grounding fault will evolve into the BC phase grounding fault; Single-phase grounding fault is C phase grounding. When , it is judged that the C phase grounding fault will evolve into the CA phase grounding fault; Single-phase grounding fault is C phase grounding. When the C phase grounding fault is about to evolve into the BC phase grounding fault; Two-phase grounding fault is AB phase grounding. When , it is judged that the AB phase grounding fault will evolve into the ABC phase grounding fault; Two-phase grounding fault is BC phase grounding. When , it is judged that the BC phase grounding fault will evolve into the ABC phase grounding fault; Two-phase grounding fault is CA phase grounding. When , it is judged that the CA phase grounding fault will evolve into the ABC phase grounding fault; The two-phase fault is between phases AB. When , it is judged that the AB phase fault will evolve into an AB phase grounding fault; The two-phase fault is between phases BC. When , it is judged that the BC phase-to-phase fault will evolve into a BC phase-to-ground fault; The two-phase fault is between CA phases. When , it is judged that the CA phase-to-phase fault will evolve into a CA phase-to-ground fault; The two-phase fault is between phases AB. When , it is judged that the AB phase fault will evolve into the ABC phase fault; The two-phase fault is between phases BC. When , it is judged that the BC phase fault will evolve into the ABC phase fault; The two-phase fault is between CA phases. When , it is judged that the CA phase fault will evolve into the ABC phase fault; Among them, k1, k2, k3, k4 and k5 are proportional coefficients.

5. The method for identifying transmission line developmental faults based on Clarke transform according to claim 4, characterized in that: Among them, the value range of k1 is 1.1~1.3, the value range of k2 is 0.8~0.9, the value range of k3 is 0.7~0.9, the value range of k4 is 1.2~1.5, and the value range of k5 is 1.1~1.

4.

6. A transmission line development fault identification system based on Clarke transform, characterized in that: include: A three-phase current signal acquisition unit is configured to acquire three-phase current signals of the transmission line in real time, including three-phase current signals in a normal operating state, three-phase current signals in an initial fault state, and three-phase current signals after an initial fault; an initial fault type determination unit, configured to, based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, obtain a fundamental frequency signal of the three-phase current signal in the normal operating state and a fundamental frequency signal of the three-phase current signal in the initial fault state by fast Fourier transform, and then determine the initial fault type of the faulty transmission line based on amplitude changes of the fundamental frequency signals in the normal operating state and the initial fault state; The special phase determination unit is configured to determine the special phase based on characteristic information of the determined initial fault type, and determine the order of inputting phase data of the three-phase current signal in the Clarke transform based on the determined special phase; wherein, when the initial fault type is phase A grounded, phase BC short-circuited, and phase BC grounded, the special phase is determined to be phase A; when the initial fault type is phase B grounded, phase CA short-circuited, and phase CA grounded, the special phase is determined to be phase B; and when the initial fault type is phase C grounded, phase AB short-circuited, and phase AB grounded, the special phase is determined to be phase C. a line mode component and zero mode component determination unit, configured to perform Clarke transform on the three-phase current signal in the normal operating state, the three-phase current signal in the initial fault state, and the three-phase current signal after the initial fault, respectively, based on the determined phase data input sequence, to obtain the line mode components and zero mode components in the normal operating state, the initial fault state, and the post-initial fault state; The developmental fault judgment unit is constructed to compare the amplitudes of the line mode component and zero mode component obtained after the initial fault with the line mode component and zero mode component of the normal operating state or the initial fault state based on the initial fault type, so as to judge whether a developmental fault occurs and the developmental fault type that the initial fault type will evolve into.

7. An electronic device, characterized in that: The electronic device comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the transmission line development fault identification method based on Clarke transform according to any one of claims 1 to 5.

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