Electromagnetic time reversal fault positioning method, system and device based on characteristic frequency matching and medium

Abstract

The invention relates to the technical field of power faults, and discloses an electromagnetic time reversal fault positioning method, system and device based on characteristic frequency matching and a medium, and the method comprises the steps: setting an observation point at any terminal in a power system, measuring and recording a fault high-frequency transient signal, and solving the characteristic frequency of the fault high-frequency transient signal; constructing a power system simulation model, injecting a pulse signal into the observation point of the simulation model, setting different guess short circuit fault points, and collecting current at the guess short circuit point positions; and based on the fault currents of the plurality of guess short-circuit fault points, obtaining the characteristic frequencies of the fault currents of the plurality of guess short-circuit fault points, and judging the fault current characteristic frequency which is the same as the characteristic frequency of the observation point so as to determine the fault position. The method can be suitable for fault positioning under a complex power grid line, the calculation efficiency is improved, and calculation is more concise.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power failure, and in particular to an electromagnetic time reversal fault location method, system, device and medium based on characteristic frequency matching. BACKGROUND

[0002] Accurate fault location is crucial for distribution network, which can shorten the outage time, reduce the cost of repairing the fault line and improve the reliability of power supply. The complex structure and multiple branches of the distribution network bring challenges to fault location.

[0003] Common fault location methods include impedance method and traveling wave method. The former has simple algorithm and is easy to implement, but the positioning result is greatly affected by fault resistance, which cannot be applied to multi-terminal distributed distribution network. The traveling wave method has small influence on line parameters, fault resistance and operation mode, and has been widely applied. The positioning of the traveling wave method in the distribution network needs to place traveling wave sensing devices at multiple points, and the fault point is located according to the distributed sensing results combined with the actual structure of the line. Electromagnetic time reversal (EMTR) is a fault location method proposed in recent years, which does not need to identify the traveling wave front, only needs to place a single fault transient signal acquisition point in the line, and is suitable for distribution networks of different complexity and hybrid lines composed of overhead lines and cables. However, the existing EMTR positioning method is difficult to apply to fault location under complex structure, and it requires a high sampling frequency of the transient signal, so a high sampling frequency voltage acquisition device is needed, which makes it difficult to apply in actual situation. SUMMARY

[0004] In view of the above existing problems, the present application is proposed. Therefore, the present application provides an electromagnetic time reversal fault location method based on characteristic frequency matching to solve the above problems.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] In the first aspect, the present application provides an electromagnetic time reversal fault location method based on characteristic frequency matching, comprising:

[0007] An observation point is set at any terminal in the power system, and a fault high-frequency transient signal is measured and recorded, and the characteristic frequency of the fault high-frequency transient signal is solved;

[0008] A power system simulation model is constructed, a pulse signal is injected into the observation point of the simulation model, different guessed short-circuit fault points are set, and the current at the guessed short-circuit point position is collected;

[0009] Based on the fault current of the plurality of guessed short-circuit fault points, the characteristic frequency of the fault current of the plurality of guessed short-circuit fault points is obtained, the fault current characteristic frequency same as the observation point characteristic frequency is judged to determine the fault location.

[0010] As a preferred scheme of the electromagnetic time reversal fault location method based on characteristic frequency matching, the measuring and recording of the fault high-frequency transient signal comprises:

[0011] After the line fault occurs, the transient traveling wave voltage u(t) from the fault in the observation point within a time length is collected by the signal collector on the line, t∈[tk, tk+T], wherein tk represents the measurement starting time, and T represents the signal sampling time length.

[0012] Based on the transient traveling wave voltage, the characteristic frequency is solved by the time-frequency feature extraction method.

[0013] The beneficial effect of the preferred scheme is that the multiple observation station data communication and time synchronization are not required, the hardware cost is reduced, and the positioning error is reduced.

[0014] As a preferred scheme of the electromagnetic time reversal fault location method based on characteristic frequency matching, the solving of the characteristic frequency comprises:

[0015] The transient traveling wave voltage u(t) is subjected to Fourier decomposition, and the frequency corresponding to the maximum amplitude after Fourier transform is taken as the characteristic frequency.

[0016] As a preferred scheme of the electromagnetic time reversal fault location method based on characteristic frequency matching, the collection of the current at the guessed short-circuit point position comprises:

[0017] The pulse signal is injected at the observation point, and the current pulse response is obtained.

[0018] A plurality of guessed short-circuit fault points are arranged at different positions, and the current signals of the guessed short-circuit fault points are collected through the current pulse response.

[0019] As a preferred scheme of the electromagnetic time reversal fault location method based on characteristic frequency matching, the solving of the characteristic frequency f DT is represented as:

[0020]

[0021] wherein u(t) represents the transient traveling wave voltage, represents the Fourier transform result of the transient traveling wave voltage; arg f max represents the maximum value.

[0022] As a preferred scheme of the electromagnetic time reversal fault location method based on characteristic frequency matching, wherein: the characteristic frequency f of the fault current of the plurality of guessed short-circuit fault points is obtained RT , is expressed as:

[0023]

[0024] Wherein, i(t) is the fault current of the guessed short-circuit fault point, is the Fourier transform result of the fault current of the guessed short-circuit fault point; arg f max represents the maximum value.

[0025] As a preferred scheme of the electromagnetic time reversal fault location method based on characteristic frequency matching, wherein: the characteristic frequency f of the fault current of the plurality of guessed short-circuit fault points is obtained

[0026]

[0027] Wherein, f represents the characteristic frequency of the observation point f DT (x f ) is the same as the characteristic frequency f RT of the fault current of the guessed short-circuit fault point.

[0028] The beneficial effect of the preferred scheme is that it can be applied to fault location in complex power grid lines, and the calculation efficiency is improved.

[0029] In a second aspect, the present application provides an electromagnetic time reversal fault location system based on characteristic frequency matching, comprising:

[0030] A first acquisition module is used to set an observation point at any terminal in a power system, measure and record fault high-frequency transient signals, and solve the characteristic frequency of the fault high-frequency transient signals;

[0031] A second acquisition module is used to construct a power system simulation model, inject a pulse signal into the observation point of the simulation model, set different guessed short-circuit fault points, and collect the current at the guessed short-circuit point position;

[0032] An output module is used to obtain the characteristic frequency f of the fault current of a plurality of guessed short-circuit fault points based on the fault current of a plurality of guessed short-circuit fault points, judge the characteristic frequency of the fault current that is the same as the characteristic frequency of the observation point, and determine the fault location.

[0033] In a third aspect, the present application provides a computer device, comprising:

[0034] A memory and a processor;

[0035] The memory is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions, and the computer executable instructions, when executed by the processor, implement the steps of the electromagnetic time reversal fault location method based on characteristic frequency matching.

[0036] In a fourth aspect, the present application provides a computer readable storage medium storing computer executable instructions, and the computer executable instructions, when executed by a processor, implement the steps of the electromagnetic time reversal fault location method based on characteristic frequency matching.

[0037] Compared with the prior art, the present application has the following beneficial effects: the present application is based on the fault transient waveform of a single observation point, and does not need to perform data communication and time synchronization of multiple observation stations, thereby reducing the hardware cost and eliminating the positioning error caused by time synchronization error; the frequency matching is used as a criterion, and compared with the traditional electromagnetic time reversal positioning method, the present application can be applied to fault location under a complex power grid line, thereby improving the calculation efficiency and making the calculation more simple. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0039] Figure 1 The figure is a schematic diagram of the overall process of the electromagnetic time reversal fault location method based on characteristic frequency matching according to an embodiment of the present application.

[0040] Figure 2 The figure is a schematic diagram of the experimental setting configuration of the electromagnetic time reversal fault location method based on characteristic frequency matching according to an embodiment of the present application.

[0041] Figure 3 The figure is a schematic diagram of the transient voltage and the corresponding frequency of the electromagnetic time reversal fault location method based on characteristic frequency matching according to an embodiment of the present application.

[0042] Figure 4 The figure is a schematic diagram of the traditional EMTR fault location result of the electromagnetic time reversal fault location method based on characteristic frequency matching according to an embodiment of the present application.

[0043] Figure 5 The figure is a schematic diagram of the fault current corresponding to pulse injection and the characteristic frequency of the electromagnetic time reversal fault location method based on characteristic frequency matching according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0045] Reference Figure 1 For an embodiment of the present application, an electromagnetic time reversal fault location method based on characteristic frequency matching is provided, comprising:

[0046] S101, setting an observation point at any terminal in the power system, measuring and recording a fault high-frequency transient signal, and solving a characteristic frequency of the fault high-frequency transient signal;

[0047] S102, constructing a power system simulation model, injecting a pulse signal into the observation point of the simulation model, setting different guessed short-circuit fault points, and collecting currents at the guessed short-circuit point positions;

[0048] S103, based on the fault currents of the plurality of guessed short-circuit fault points, obtaining the characteristic frequencies of the fault currents of the plurality of guessed short-circuit fault points, judging the fault current characteristic frequencies same as the observation point characteristic frequency, and determining the fault position.

[0049] In a preferred embodiment, measuring and recording the fault high-frequency transient signal comprises:

[0050] After a line fault occurs, a transient traveling wave voltage u(t) from the fault in the observation point within a time duration is collected by a signal collector on the line, t∈[tk,tk+T], wherein tk represents a measurement starting time, and T represents a signal sampling time length.

[0051] Based on the transient traveling wave voltage, a characteristic frequency is solved by a time-frequency feature extraction method.

[0052] Specifically, after a line fault occurs, a transient traveling wave voltage from a fault point can be obtained by a voltage sensor and other signal collection devices on the line, and a voltage transient signal of a limited duration is recorded.

[0053] In an alternative embodiment, the fault high-frequency transient signal can also be transient current traveling wave data, i.e. high-frequency transient component of line phase current, the current signal is collected from the secondary side of the current transformer (CT) of the observation point, the current waveform at the fault moment is recorded, the power frequency component is filtered out through signal processing technology, and the high-frequency transient current traveling wave is extracted. The voltage step at the fault point will cause corresponding current wave on the line, and the current traveling wave also carries complete fault information. The current is small during normal operation of the system, and the current increases suddenly at the fault moment, the amplitude of the transient current traveling wave is very large, easy to detect and identify, and has strong anti-interference ability.

[0054] In another alternative embodiment, the transient signal can also be used to obtain the characteristic frequency of the fault by measuring the transient magnetic field or integrated electromagnetic radiation field generated around the conductor at the fault moment. The fault traveling wave current will generate a strong, high-frequency alternating magnetic field around the conductor, and the strength and rate of change of the magnetic field contain frequency information corresponding to the current traveling wave. The current and the magnetic field are closely coupled, and the high-frequency current traveling wave generated by the fault will immediately excite a high-frequency magnetic field of the same frequency around the space. Therefore, the frequency characteristics of the measured transient magnetic field signal are completely equivalent to the transient current traveling wave.

[0055] In a preferred embodiment, solving the characteristic frequency includes:

[0056] Fourier decomposition is performed on the transient traveling wave voltage u(t), and the frequency corresponding to the maximum amplitude after Fourier transform is taken as the characteristic frequency.

[0057] Specifically, the characteristic frequency f DT is represented as:

[0058]

[0059] wherein u(t) represents the transient traveling wave voltage, represents the Fourier transform result of the transient traveling wave voltage; arg f max represents the maximum value. Therefore, f DT has the physical meaning of the frequency f corresponding to the maximum amplitude after Fourier transform of the fault transient voltage u(t).

[0060] In an alternative embodiment, the characteristic frequency solved by the time-frequency feature extraction method can also be the short-time Fourier transform method. A long signal is divided into many short time periods through a sliding window function, and then a two-dimensional time-frequency distribution (spectrum diagram) is obtained by performing fast Fourier transform on each period, thereby providing information of the frequency change of the signal with time, and thereby obtaining the characteristic spectrum.

[0061] In another alternative implementation, the characteristic frequency can be determined by wavelet transform, using a scalable and translational wavelet basis function (mother wavelet) to fit the signal. By "scaling" to change the frequency and "translating" to change the time position, it is possible to "focus" on any detail of the signal. It has high time resolution and low frequency resolution in the high-frequency range, and high frequency resolution and low time resolution in the low-frequency range, which is very consistent with the characteristics of transient traveling wave signals (high-frequency components have short durations). It has multi-resolution characteristics, can adaptively analyze signals, effectively extract local features of the signal, and accurately characterize when a specific frequency appears and its energy level.

[0062] In a preferred embodiment, the characteristic frequency f of the fault current at multiple hypothesized short-circuit fault points is obtained. RT , is represented as:

[0063]

[0064] Where i(t) is the fault current at the predicted short-circuit fault point. To predict the Fourier transform result of the fault current at the short-circuit fault point; arg| f `max` represents the maximum value.

[0065] Specifically, a power system simulation model is established based on the line parameters of the power system, including line length, type, and distributed parameters. A pulse signal is injected into the power system simulation model, and a short-circuit fault is simulated by grounding. A hypothetical short-circuit fault point is then determined, and the current response i at the hypothetical fault point location xf is simulated. f (x f For each point i obtained, f (x f Fourier decomposition was performed to obtain the characteristic frequencies f of the fault currents at multiple locations. RT (x f ), by finding f DT The same f RT (x f The location of the fault is determined by guessing the location of the fault.

[0066] In a preferred embodiment, the fault current characteristic frequency, which is the same as the characteristic frequency of the observation point, is determined to determine the fault location, expressed as follows:

[0067]

[0068] in, The characteristic frequency f of the observation point DT The characteristic frequency f of the fault current at the short-circuit fault point is guessed. RT (x f) the same time frequency value.

[0069] It should be noted that the present application is based on the fault transient waveform of a single observation point, without the need for multiple observation station data communication and time synchronization, which reduces the hardware cost while eliminating the positioning error introduced by time synchronization error; using frequency matching as a criterion, compared with the traditional electromagnetic time reversal positioning method, it can be applied to fault location under complex power grid lines, improve the calculation efficiency, and the calculation is more simple.

[0070] The above is a schematic scheme of the electromagnetic time reversal fault location method based on feature frequency matching of the present embodiment. It should be noted that the technical scheme of the electromagnetic time reversal fault location system based on feature frequency matching belongs to the same concept as the technical scheme of the electromagnetic time reversal fault location method based on feature frequency matching described above. The technical scheme of the electromagnetic time reversal fault location system based on feature frequency matching in the present embodiment is not described in detail. The details can be referred to the description of the technical scheme of the electromagnetic time reversal fault location method based on feature frequency matching.

[0071] Embodiment 2

[0072] The present embodiment provides an electromagnetic time reversal fault location system based on feature frequency matching, comprising:

[0073] The first acquisition module is used to set an observation point at any terminal in the power system, measure and record the fault high-frequency transient signal, and solve the feature frequency of the fault high-frequency transient signal;

[0074] The second acquisition module is used to construct a power system simulation model, inject a pulse signal into the observation point of the simulation model, set different guessed short-circuit fault points, and collect the current at the guessed short-circuit point position;

[0075] The output module is used to obtain the feature frequency of the fault current of the plurality of guessed short-circuit fault points based on the fault current of the plurality of guessed short-circuit fault points, judge the fault current feature frequency that is the same as the observation point feature frequency, and determine the fault location.

[0076] The present embodiment also provides a computer device suitable for electromagnetic time reversal fault location based on feature frequency matching, comprising:

[0077] The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to realize the electromagnetic time reversal fault location method based on feature frequency matching as proposed in the above embodiment.

[0078] The embodiment also provides a storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method for electromagnetic time reversal fault location based on characteristic frequency matching.

[0079] The storage medium provided by the embodiment belongs to the same inventive concept as the method for electromagnetic time reversal fault location based on characteristic frequency matching, and the technical details not described in the embodiment can be referred to the above embodiment, and the embodiment has the same beneficial effects as the above embodiment.

[0080] From the above description of the embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software and necessary universal hardware, and of course, it can also be implemented by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present application or the part that contributes to the prior art can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a floppy disk, a read-only memory (ROM), a random access memory (RAM), a FLASH, a hard disk or an optical disk, etc., including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the method of each embodiment of the present application.

[0081] Embodiment 3

[0082] Reference Figures 2-5 For an embodiment of the present application, a method for electromagnetic time reversal fault location based on characteristic frequency matching is provided, and in order to verify its beneficial effects, economic benefit calculation and simulation experiments are used for scientific demonstration.

[0083] The experiment is based on a scaled coaxial cable system, and the proposed fault location method is verified. The platform includes a 61m coaxial cable, an arbitrary waveform generator and an oscilloscope, as shown in Figure 2 The power supply voltage is provided by the arbitrary waveform generator, which is connected in series with a lumped resistor R1, which is used as the input impedance of the transient traveling wave of the transformer in the primary substation. The fault is set at 51 meters, 56 meters and 61 meters. The current at the fault point is collected by the Pearson coil 110A, and the variable ratio is 0.1V / A.

[0084] For step S101, the oscilloscope directly records Figure 2 the voltage of the observation point, and the transient voltage collected at the observation point is subjected to Fourier decomposition, and the result is shown in Figure 3 .

[0085] At step S102, the pulse signal is injected into the line, different fault points are set, and then the Pearson coil 110A is used to collect the current corresponding to the fault points. At step S103, the Fourier decomposition is performed on the obtained fault current of each point to solve the characteristic frequency.

[0086] Figure 3 For the transient voltage and the corresponding frequency, the characteristic frequencies obtained after the signal is subjected to the FFT are 1.85, 1.65 and 1.5 MHz respectively.

[0087] Figure 4 The positioning results of the traditional electromagnetic time reversal method are 20 meters respectively, and the positioning results of the proposed method are the same as the actual situation.

[0088] Figure 5 For setting different fault distances of 51, 56 and 61 m, the current corresponding to the fault points is collected, and the characteristic frequencies corresponding to 51, 56 and 61 m are 1.85, 1.65 and 1.5 MHz respectively, which are the same as the characteristic frequencies of the transient voltage. Figure 2 The obtained fault positioning results are 51, 56 and 61 m respectively.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. An electromagnetic time reversal fault location method based on characteristic frequency matching, characterized in that, The method comprises the following steps: Setting an observation point at any terminal in a power system, measuring and recording a fault high-frequency transient signal, and solving a characteristic frequency of the fault high-frequency transient signal; Building a simulation model of the power system, injecting a pulse signal into the observation point of the simulation model, setting different guessed short-circuit fault points, and collecting currents at the guessed short-circuit point positions; Based on the fault currents of multiple guessed short-circuit fault points, obtaining the characteristic frequencies of the fault currents of multiple guessed short-circuit fault points, judging the fault current characteristic frequencies same as the observation point characteristic frequency, and determining the fault position.

2. The electromagnetic time reversal fault location method based on characteristic frequency matching according to claim 1, characterized in that, Measuring and recording a fault high-frequency transient signal comprises the following steps: After a line fault occurs, a transient traveling wave voltage u(t) from the fault in the observation point within a time length is collected by a signal collector on the line, t∈[tk,tk+T], wherein tk represents a measurement starting time, and T represents a signal sampling time length; Based on the transient traveling wave voltage, a characteristic frequency is solved by a time-frequency feature extraction method.

3. The electromagnetic time reversal fault location method based on characteristic frequency matching according to claim 2, characterized in that, Solving a characteristic frequency comprises the following steps: The transient traveling wave voltage u(t) is Fourier decomposed, and a frequency corresponding to a maximum amplitude after Fourier transform is taken as a characteristic frequency.

4. The electromagnetic time reversal fault location method based on characteristic frequency matching of claim 1, wherein, Collecting currents at the guessed short-circuit point positions comprises the following steps: Injecting a pulse signal into the observation point to obtain a current pulse response; Multiple guessed short-circuit fault points are set at different positions, and currents of the guessed short-circuit fault points are collected through the current pulse response.

5. The electromagnetic time reversal fault location method based on characteristic frequency matching of claim 3, wherein, Solving the characteristic frequency f DT is represented as: where u(t) represents the transient traveling wave voltage, the Fourier transform result of the transient traveling wave voltage; arg f max represents the maximum value.

6. The electromagnetic time reversal fault location method based on characteristic frequency matching according to claim 5, characterized in that, obtaining a characteristic frequency f of the fault current of a plurality of the guessed short-circuit fault points RT is expressed as: where i(t) is the fault current of the guessed short-circuit fault point, is the Fourier transform result of the fault current of the guessed short-circuit fault point; arg f max represents the maximum value.

7. The electromagnetic time reversal fault location method based on characteristic frequency matching of claim 6, wherein, Judging the fault current characteristic frequencies same as the observation point characteristic frequency to determine the fault position is represented as: wherein, represents the characteristic frequency f of the observation point DT with the characteristic frequency f of the guessed short-circuit fault point fault current RT (x f ) is the same frequency value.

8. An electromagnetic time reversal fault location system based on eigenfrequency matching, applying an electromagnetic time reversal fault location method based on eigenfrequency matching according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: A first collection module is configured to set an observation point at any terminal in a power system, measure and record a fault high-frequency transient signal, and solve a characteristic frequency of the fault high-frequency transient signal; A second collection module is configured to build a simulation model of the power system, inject a pulse signal into the observation point of the simulation model, set different guessed short-circuit fault points, and collect currents at the guessed short-circuit point positions; An output module is configured to obtain characteristic frequencies of fault currents of multiple guessed short-circuit fault points based on the fault currents of the multiple guessed short-circuit fault points, judge fault current characteristic frequencies same as an observation point characteristic frequency, and determine a fault position.

9. A computer device, comprising: The method comprises the following steps: A memory and a processor; The memory is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions, so as to realize the steps of the method for electromagnetic time reversal fault positioning based on characteristic frequency matching according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The memory stores computer executable instructions, and the processor is configured to execute the computer executable instructions, so as to realize the steps of the method for electromagnetic time reversal fault positioning based on characteristic frequency matching according to any one of claims 1 to 7.

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