Developing fault identification method and system for power transmission line based on Clark transformation

Abstract

The invention discloses a method and a system for identifying a developmental fault of a power transmission line based on Clark transform, and the method comprises the steps: determining an initial fault type based on the amplitude break variable in fundamental frequency signals of a normal operation state and an initial fault state of the power transmission line, which are extracted through Fourier transform; determining a special phase based on the initial fault type, determining a phase data input sequence of a three-phase current signal in the Clark transformation based on the special phase, and performing the Clark transformation to obtain a normal operation state, an initial fault state and a line mode component and a zero mode component after the initial fault; and judging a developmental fault type which is about to be evolved from the initial fault type by comparing amplitude changes of the line mode component and the zero mode component respectively. By comparing the amplitude change of the line mode component and the zero mode component during normal operation, the initial fault and the amplitude change after the initial fault, which fault the initial fault is about to develop into can be quickly and accurately judged, so that the accuracy of relay protection and fault phase selection is improved.

Description

Technical Field

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

[0002] Transmission lines are exposed to the atmosphere for a long time and are susceptible to failures caused by lightning strikes, strong winds, foreign objects, dirt, ice, etc. If the faults on the transmission lines cannot be removed in time and they are in an abnormal operating state for a long time, they will lead to more serious faults and even cause large-scale power outages.

[0003] A developing fault refers to the situation where the same fault point develops from a single-phase fault to a phase-to-phase or even a three-phase fault due to the expansion or transformation of the factors that caused the fault. Although the probability of a developing fault is much lower than that of a single fault, the harm to the power system is far greater than that of a single fault. If the developing fault cannot be removed correctly and in time, it will cause the phase selection element to misselect the phase and the protection device to malfunction, causing a secondary impact on the power grid. Therefore, if the developing fault can be identified in a timely and accurate manner and corresponding measures can be taken, the fault can be prevented from further expanding and the stability of the power system operation can be improved.

[0004] At present, there are few methods for identifying developmental faults in transmission lines. Traditional methods mainly judge based on the difference or ratio between the voltage and current sequence components after the fault, and manually select appropriate thresholds as fault judgment criteria. However, problems such as asymmetric three-phase parameters and improper threshold selection are likely to affect the recognition effect of these methods. Artificial intelligence algorithms combined with deep learning need to rely on a large number of data sets for training, which is incompatible with the small number of developmental fault samples. In summary, there is still a lack of methods that can accurately, reliably and quickly identify developmental 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 developmental faults in transmission lines based on Clarke transform, which can quickly and reliably determine whether a developmental fault has occurred and the developmental fault that the initial fault will evolve into 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, thereby solving the problem of incorrect phase selection caused by phase selection elements due to developmental faults in transmission lines.

[0006] To achieve the above purpose, 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 sequence 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, respectively, to obtain the line mode component and the zero mode component 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, so as to effectively obtain the line mode component and the zero mode component under normal operating state, the initial fault state and after the initial fault state based on the characteristic information of the specific initial fault, and then by comparing the obtained line mode component and the zero mode component after the initial fault with the amplitude of the line mode component and the zero mode component in the normal operating state or the line mode component and the 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, on the basis of 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 It 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 the fault occurs, so as to facilitate the rapid positioning of the time and location of the fault. In addition, since the three-phase current signal is acquired in real time, it is not only possible to detect the initial fault (i.e., the type of fault that is occurring) and judge its type in real time, but also to judge whether a developmental fault occurs and the type of the developmental fault 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, so there is no need to adopt different and incoherent methods to judge the initial fault and the developmental fault respectively as in the prior art.

[0014] It should be emphasized that the so-called "after the initial fault" refers to the state when the initial fault just 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 mutation 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, as shown in Table 1 below.

[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 transformation 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 transformation 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 transformation is determined as follows: When the special phase is phase C, the order of inputting the phase data of the three-phase current signal in the Clarke transformation is determined as follows:

[0021] In the present invention, the three-phase current signal is Clarke transformed into line mode components and zero mode components, and 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 transformation on the three-phase current signal, the line mode component and zero mode component of 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 transformation, the line mode components are 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 in 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 Clarke is obtained.

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

[0033] In a preferred embodiment, the step of determining the type of developing fault includes: 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 is 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 fault is about to evolve into the ABC phase grounding fault, the BC phase grounding fault will be 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 CA grounding will evolve into the phase ABC grounding; the two-phase fault is between the phases AB. When the AB phase is about to become the AB phase grounding; the two-phase fault is the BC phase. When BC phase-to-phase fault is about to evolve into BC phase-to-phase grounding, the two-phase fault is CA phase-to-phase 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 CA and CA. When the AB phase will evolve into the ABC phase; the two-phase fault is the BC phase. When BC phase will evolve into ABC phase; the two-phase fault is 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 in 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 the three-phase current signal of the transmission line in real time, including 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;

[0040] The initial fault type determination unit is constructed to obtain the base frequency signal of the three-phase current signal in the normal operating state and the base frequency signal of the three-phase current signal in the initial fault state through fast Fourier transform based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, and then determine the initial fault type of the faulty power transmission line based on the amplitude change of the base frequency signal in the normal operating state and the initial fault state;

[0041] A special phase determination unit is configured to determine the special phase based on the characteristic information of the determined initial fault type, and determine the phase data input sequence of the three-phase current signal in Clarke transformation based on the determined special phase;

[0042] A line mode component and zero mode component determination unit is constructed to, based on the phase data input sequence determined in step S3, perform Clarke transformation 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, so as to obtain the line mode component and the zero mode component in the normal operating state, the initial fault state, and after the initial fault, 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 into which the initial fault type will evolve.

[0044] The third aspect of the present invention discloses an electronic device, including a memory and a processor, the memory is used to store computer programs, 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 Clarke transformation through a special phase for the first time, and then performs Clarke transformation 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, and quickly and reliably judges the developmental fault that the initial fault will evolve into, greatly improving the accuracy of relay protection and fault phase selection, and effectively solving the problem of phase selection components misselecting phases due to developmental faults in existing transmission lines. In addition, the phase-specific data input sequence of the three-phase current signal in the Clarke transformation is determined based on the special phase determined by the initial fault, so as to obtain the comparison parameters of the line mode component and the zero mode component after the developmental fault, and improves the accuracy of judging the developmental fault that the initial fault will evolve into, so that the present invention can accurately judge what kind of two-phase grounding fault will evolve into when the initial fault is a single-phase grounding fault; can accurately judge what will evolve into a three-phase grounding fault when the initial fault is a two-phase grounding fault; can also accurately judge what will evolve into a phase-to-phase fault and a three-phase-to-phase fault when 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 in conjunction with the embodiments shown in the accompanying drawings and the accompanying drawing numbers. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0049] Figure 2 The three-phase current i is the current i when the A-phase grounding fault develops into the AB-phase grounding fault in the present invention. ABC With 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 diagram;

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

[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 diagram;

[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 technical solutions in the embodiments of the present invention will be described clearly and completely below 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 the field without 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 without conflict.

[0055] like Figure 1 As shown, the present invention discloses a method for identifying developmental faults of a power transmission line 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 acquired through 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 initial fault state; S3, based on the characteristic information of the determined initial fault type, the special phase is determined, and the Clarke signal 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] The present invention compares the amplitude changes of line mode components in normal operation, initial faults and developing faults to 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 should be selected according to the actual situation.

[0059] Furthermore, in step S2, the three-phase current signal in the normal operating state and the three-phase current signal 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 is 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 fundamental frequency amplitude mutation amount of these two phases is obvious in the spectrum, and the current amplitude of phase C remains basically unchanged, so its fundamental frequency amplitude is relatively stable on the spectrum, and the initial fault is determined based on this.

[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 transformation is determined as follows: When the special phase is phase B, the order of inputting the phase data of the three-phase current signal in the Clarke transformation is determined as follows: When the special phase is phase C, the order of inputting the phase data of the three-phase current signal in the Clarke transformation is determined as follows:

[0062] In the present invention, the three-phase current signal is Clarke transformed into line mode components and zero mode components, and 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 transformation on the three-phase current signal, the line mode component and zero mode component of 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 in 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 Clarke is obtained.

[0072] In the embodiment of the present invention, in step S5, based on the initial fault type, the line mode component and the zero mode component after the initial fault are compared with the line mode component and the zero mode component of the normal operation state or the initial fault state, respectively, so as to judge whether a fault occurs and the developmental fault type 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 β mode component after the initial fault. The amplitude of the β-mode component of the initial fault state To compare and based on and The amplitude change after comparison is used to judge the developing fault that the single-phase grounding fault will evolve into; 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 To compare and based on and The amplitude change after comparison is used to judge the developing fault that the single-phase grounding fault will evolve into; 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 For comparison or to compare the amplitude of the α mode component after the initial fault The amplitude of the α-mode component in normal operation To compare and based on and The amplitude change after comparison or and The amplitude changes after comparison are used to determine whether the two-phase interphase 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 is 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 fault is about to evolve into the ABC phase grounding fault, the BC phase grounding fault will be 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 CA grounding will evolve into the phase ABC grounding; the two-phase fault is between the phases AB. When the AB phase is about to become the AB phase grounding; the two-phase fault is the BC phase. When BC phase-to-phase fault is about to evolve into BC phase-to-phase grounding, the two-phase fault is CA phase-to-phase 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 CA and CA. When the AB phase will evolve into the ABC phase; the two-phase fault is the BC phase. When BC phase will evolve into ABC phase; the two-phase fault is 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 i when the A-phase grounding fault develops into the AB-phase grounding fault in the present invention. ABC With 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 IIA 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 The data displayed shows a one-to-one correspondence between each stage 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 It is not difficult to see in (a) and (b) 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 is lower than that of 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] Embodiment 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] Embodiment 3: Two-phase interphase fault develops into two-phase grounding 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 fluctuating 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 is higher than that of the initial fault stage, which meets the criterion set up. Figure 5 (a), (c), (e) The results of the other two-phase faults developing into two-phase grounding faults also verify that the judgment basis is set correctly.

[0082] Embodiment 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 diagram 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 operation state, the amplitude fluctuates slightly. After the development fault (i.e., the BC phase fault develops into the ABC phase fault) The amplitude of is greatly increased compared with the normal operation 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 embodiments, the present invention determines the special phase through the initial fault information, changes the input order of Clarke transformation, and compares and analyzes the amplitude changes of line mode components and zero mode components during normal operation, initial fault, and after the initial fault to accurately and quickly identify the single-phase grounding fault developing into a two-phase grounding fault, the initial fault phase developing into a fault when the two-phase grounding fault develops into a three-phase grounding fault, the two-phase interphase fault develops into a two-phase grounding fault, and the two-phase interphase fault develops into a three-phase interphase fault. The effectiveness and reliability of the present invention are verified through theoretical derivation and a large number of results analysis, and the method can be applied to most power system transmission line development fault identification fields.

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

[0086] A three-phase current signal acquisition unit is configured to acquire the three-phase current signal of the transmission line in real time, including 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;

[0087] The initial fault type determination unit is constructed to obtain the base frequency signal of the three-phase current signal in the normal operating state and the base frequency signal of the three-phase current signal in the initial fault state through fast Fourier transform based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, and then determine the initial fault type of the faulty power transmission line based on the amplitude change of the base frequency signal in the normal operating state and the initial fault state;

[0088] A special phase determination unit is configured to determine the special phase based on the characteristic information of the determined initial fault type, and determine the phase data input sequence of the three-phase current signal in Clarke transformation based on the determined special phase;

[0089] A line mode component and zero mode component determination unit is constructed to, based on the phase data input sequence determined in step S3, perform Clarke transformation 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, so as to obtain the line mode component and the zero mode component in the normal operating state, the initial fault state, and after the initial fault, 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 into which the initial fault type will evolve.

[0091] The present invention also discloses an electronic device, including 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 several embodiments provided in the present 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 schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to 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 a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order 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 with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0093] In addition, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may 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 can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods 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 above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0096] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

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

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. 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 solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for identifying developmental faults in power transmission lines 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 a phase data input order of the three-phase current signal in Clarke transformation based on the determined special phase; S4, based on the phase data input sequence 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, respectively, to obtain the line mode component and the 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, 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.

2. The method for identifying transmission line developmental faults based on Clarke transform according to claim 1 is characterized in that: In step S3, determining a special phase based on the characteristic information of the determined initial fault type includes: 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 grounding, phase CA short circuit, and phase CA grounding, 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.

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

4. The method for identifying transmission line developmental faults based on Clarke transform according to claim 3 is characterized in that: In step S5, the amplitudes of the line mode components in the normal operation state are defined as Amplitude of the zero mode component The amplitudes of the line mode components in 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 judging whether a fault occurs and the developmental fault type to which the initial fault type will evolve based on the amplitude change 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 To compare and based on and The amplitude change after comparison determines the developing fault that the single-phase grounding fault will evolve into; 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 To compare and based on and The amplitude change after comparison determines the developing fault that the single-phase grounding fault will evolve into; 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 or compare the amplitude of the α mode component after the initial fault The amplitude of the α-mode component in normal operation To compare and based on and The amplitude change after comparison or and The amplitude changes after comparison are used to determine the developing fault that the two-phase fault will evolve into.

5. The method for identifying developmental faults of power transmission lines based on Clarke transform according to claim 4 is characterized in that: In step S5, the step of judging the developing fault that the initial fault type will evolve into based on the compared amplitude change includes: Single-phase grounding fault is A phase grounding. When the A phase grounding fault is detected, it is judged that the A phase grounding fault will evolve into the AB phase grounding fault; Single-phase grounding fault is A phase grounding. 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. When the B phase grounding fault is detected, it is judged that the B phase grounding fault will evolve into the AB phase grounding fault; The single-phase grounding fault is the B phase grounding. 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. 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. When the C phase grounding fault is judged to be about to evolve into the BC phase grounding fault; Two-phase grounding fault is AB phase grounding. When the AB phase grounding fault is about to evolve into the ABC phase grounding fault; Two-phase grounding fault is BC phase grounding. When the BC phase grounding fault is about to evolve into the ABC phase grounding fault; Two-phase grounding fault is CA phase grounding. When the phase CA grounding fault is judged to be about to evolve into the phase ABC grounding fault; The two-phase fault is between phases AB. When , it is judged that the AB phase-to-phase fault will evolve into an AB phase-to-ground 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 the CA phase-to-phase fault is about to 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.

6. The method for identifying transmission line developmental faults based on Clarke transform according to claim 5 is 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.

7. 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 the three-phase current signal of the transmission line in real time, including 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; The initial fault type determination unit is constructed to obtain the base frequency signal of the three-phase current signal in the normal operating state and the base frequency signal of the three-phase current signal in the initial fault state through fast Fourier transform based on the three-phase current signal in the normal operating state and the three-phase current signal in the initial fault state, and then determine the initial fault type of the faulty power transmission line based on the amplitude change of the base frequency signal in the normal operating state and the initial fault state; A special phase determination unit, which is configured to 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 transformation based on the determined special phase; A line mode component and zero mode component determination unit is constructed to perform Clarke transformation 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 after the initial fault; 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 into which the initial fault type will evolve.

8. An electronic device, characterized in that: It 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 developmental fault identification method based on Clarke transform as described in any one of claims 1-6.

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