CN113391236B - Single-phase earth fault detection method and related device for resonance earth system - Google Patents
Single-phase earth fault detection method and related device for resonance earth system Download PDFInfo
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- CN113391236B CN113391236B CN202110875762.6A CN202110875762A CN113391236B CN 113391236 B CN113391236 B CN 113391236B CN 202110875762 A CN202110875762 A CN 202110875762A CN 113391236 B CN113391236 B CN 113391236B
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Abstract
The application discloses a single-phase earth fault detection method and a related device for a resonance earthing system, wherein the method comprises the following steps: extracting a zero sequence current transient component amplitude value and a zero sequence current steady-state component amplitude value from a preset zero sequence current waveform at an outlet of each line; calculating the ratio of the zero sequence current transient component amplitude to the zero sequence current steady-state component amplitude at the outlet of each line to obtain a transient steady-state amplitude ratio; sorting all the transient and steady state amplitude ratios based on a bubble sorting algorithm, and calculating the ratio of the maximum transient and steady state amplitude ratio to the minimum transient and steady state amplitude ratio to obtain the most significant ratio; and if the maximum ratio is within the preset range, judging that the bus has single-phase earth fault, otherwise, judging that the line corresponding to the maximum transient and steady-state amplitude ratio has single-phase earth fault. The method and the device can solve the technical problem that in the prior art, the dependence on CT polarity and various data information is large, so that actual operation is limited.
Description
Technical Field
The application relates to the technical field of ground fault line selection of a resonance grounding system, in particular to a single-phase ground fault detection method and a related device of the resonance grounding system.
Background
The influence of the reverse connection of the CT polarity on the line selection of the low-current ground fault cannot be ignored. However, situations sometimes occur where the CT is reversed in polarity or ambiguous in polarity. After a small current grounding fault occurs in a plurality of resonant grounding systems, the reverse connection of the zero sequence CT may cause the misoperation or non-action of a line selection device, influence the stability of the system operation and enlarge the range of fault damage. For the resonant earth fault line selection method depending on the transient current polarity, the consistency of the CT polarity at the line outlet must be ensured.
The currently disclosed ground fault line selection method can be classified into a steady-state component method, a transient component method and a comprehensive line selection method. The steady-state component method is greatly influenced by the arc suppression coil, and the reliability of line selection is reduced; the transient component method is susceptible to interference. The comprehensive line selection method needs more data information to be acquired, is complex to operate and has the problem of application limitation.
Disclosure of Invention
The application provides a single-phase earth fault detection method and a related device of a resonance earthing system, which are used for solving the technical problem that the actual operation is limited due to the fact that the prior art has large dependence on CT polarity and various data information.
In view of the above, a first aspect of the present application provides a method for detecting a single-phase ground fault of a resonant grounding system, including:
extracting a zero sequence current transient component amplitude value and a zero sequence current steady-state component amplitude value from a preset zero sequence current waveform at an outlet of each line;
calculating the ratio of the zero sequence current transient component amplitude to the zero sequence current steady-state component amplitude at the outlet of each line to obtain a transient steady-state amplitude ratio;
sorting all the transient and steady state amplitude ratios based on a bubble sorting algorithm, and calculating the ratio of the maximum transient and steady state amplitude ratio to the minimum transient and steady state amplitude ratio to obtain the most significant ratio;
and if the maximum ratio is within a preset range, judging that the bus has single-phase earth fault, otherwise, judging that the line corresponding to the maximum transient and steady-state amplitude ratio has single-phase earth fault.
Optionally, the extracting zero sequence current transient component amplitude and zero sequence current steady-state component amplitude from the preset zero sequence current waveform at the outlet of each line further includes:
and (3) presetting a zero sequence current waveform in a power frequency cycle after a fault is collected at the outlet of each line by adopting a zero sequence current transformer to obtain a preset zero sequence current waveform.
Optionally, the extracting the zero-sequence current transient component amplitude and the zero-sequence current steady-state component amplitude from the preset zero-sequence current waveform at the outlet of each line includes:
extracting a zero sequence current transient component amplitude value from a preset zero sequence current waveform at an outlet of each line according to a preset Prony algorithm;
and extracting the zero-sequence current steady-state component amplitude from the preset zero-sequence current waveform at the outlet of each line by adopting a Fourier transform algorithm.
Optionally, after sorting all the transient and steady state amplitude ratios based on the bubble sorting algorithm, calculating a ratio between a maximum transient and steady state amplitude ratio and a minimum transient and steady state amplitude ratio to obtain a maximum ratio, including:
after numbering all the transient and steady state amplitude ratio values, comparing the transient and steady state amplitude ratio values pairwise based on a bubble sorting algorithm according to numbers, and placing the smaller transient and steady state amplitude ratio value behind the larger transient and steady state amplitude ratio value to obtain the transient and steady state amplitude ratio values in descending order;
obtaining a maximum transient steady state amplitude ratio and a minimum transient steady state amplitude ratio from the transient steady state amplitude ratios in descending order;
and calculating the ratio of the maximum transient steady-state amplitude ratio to the minimum transient steady-state amplitude ratio to obtain the maximum ratio.
The present application provides in a second aspect a single-phase ground fault detection device for a resonant grounding system, comprising:
the extraction module is used for extracting a zero sequence current transient component amplitude value and a zero sequence current steady-state component amplitude value from a preset zero sequence current waveform at the outlet of each line;
the first calculation module is used for calculating the ratio of the zero-sequence current transient component amplitude value to the zero-sequence current steady-state component amplitude value at the outlet of each line to obtain a transient-state amplitude ratio;
the second calculation module is used for calculating the ratio of the maximum transient steady-state amplitude ratio to the minimum transient steady-state amplitude ratio to obtain the most significant ratio after sequencing all the transient steady-state amplitude ratios based on a bubble sequencing algorithm;
and the judging module is used for judging that the bus has single-phase earth faults if the maximum ratio is within a preset range, and otherwise, judging that the line corresponding to the maximum transient and steady-state amplitude ratio has single-phase earth faults.
Optionally, the method further includes:
and the acquisition module is used for acquiring a zero sequence current waveform in a preset power frequency cycle after a fault occurs at the outlet of each line by adopting a zero sequence current transformer to obtain a preset zero sequence current waveform.
Optionally, the extracting module is specifically configured to:
extracting a zero sequence current transient component amplitude value from a preset zero sequence current waveform at an outlet of each line according to a preset Prony algorithm;
and extracting the zero-sequence current steady-state component amplitude from the preset zero-sequence current waveform at the outlet of each line by adopting a Fourier transform algorithm.
Optionally, the second computing module includes:
the sorting submodule is used for numbering all the transient and steady state amplitude ratios, comparing every two transient and steady state amplitude ratios based on a bubble sorting algorithm according to numbers, and placing the smaller transient and steady state amplitude ratio behind the larger transient and steady state amplitude ratio to obtain the transient and steady state amplitude ratios in descending order;
the obtaining submodule is used for obtaining a maximum transient steady state amplitude ratio and a minimum transient steady state amplitude ratio from the transient steady state amplitude ratios in descending order;
and the calculation submodule is used for calculating the ratio of the maximum transient and steady state amplitude ratio to the minimum transient and steady state amplitude ratio to obtain the maximum ratio.
A third aspect of the present application provides a single-phase ground fault detection device of a resonant grounding system, the device comprising a processor and a memory;
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the method for detecting a single-phase ground fault of a resonant grounded system according to the first aspect according to instructions in the program code.
A fourth aspect of the present application provides a computer-readable storage medium for storing program code for executing the method for single-phase ground fault detection of a resonant grounded system of the first aspect
According to the technical scheme, the embodiment of the application has the following advantages:
the application provides a method for detecting a single-phase earth fault of a resonance earthing system, which comprises the following steps: extracting a zero sequence current transient component amplitude value and a zero sequence current steady-state component amplitude value from a preset zero sequence current waveform at an outlet of each line; calculating the ratio of the zero sequence current transient component amplitude to the zero sequence current steady-state component amplitude at the outlet of each line to obtain a transient steady-state amplitude ratio; sorting all the transient and steady state amplitude ratios based on a bubble sorting algorithm, and calculating the ratio of the maximum transient and steady state amplitude ratio to the minimum transient and steady state amplitude ratio to obtain the most significant ratio; and if the maximum ratio is within the preset range, judging that the bus has single-phase earth fault, otherwise, judging that the line corresponding to the maximum transient and steady-state amplitude ratio has single-phase earth fault.
The method for detecting the single-phase earth fault of the resonant grounding system can perform fault analysis only by the aid of the zero-sequence current waveform at the outlet of the line, mainly calculates the amplitude ratio of the zero-sequence current component in the analysis process, can realize fault detection without depending on CT polarity and other various data information, can determine whether the fault is a bus fault or other line faults, and is simple to operate and easy to execute. Therefore, the method and the device can solve the technical problem that in the prior art, the dependence on CT polarity and various data information is large, and actual operation is limited.
Drawings
Fig. 1 is a schematic flowchart of a single-phase ground fault detection method of a resonant grounding system according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a single-phase ground fault detection apparatus of a resonant grounding system according to an embodiment of the present application;
fig. 3 is a low-impedance ground fault equivalent circuit diagram of the resonant grounding system provided in the embodiment of the present application;
FIG. 4 is a schematic diagram of a simulation model of a ground fault of a Matlab/Simulink resonant grounding system provided in the simulation case of the present application;
fig. 5 is a waveform diagram of a transient steady-state current at a line outlet when a bus ground fault is provided by the simulation case of the present application;
FIG. 6 shows a line L provided by the simulation case of the present application5And (3) temporarily stabilizing the current waveform diagram at the line outlet during the fault.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
For easy understanding, referring to fig. 1, the present application provides an embodiment of a method for detecting a single-phase ground fault of a resonant grounding system, including:
Further, step 101 includes:
extracting a zero sequence current transient component amplitude value from a preset zero sequence current waveform at an outlet of each line according to a preset Prony algorithm;
and extracting the zero-sequence current steady-state component amplitude from the preset zero-sequence current waveform at the outlet of each line by adopting a Fourier transform algorithm.
The preset zero sequence current waveform is obtained at the outlet of the line after the line has a fault, component amplitudes of different states can be extracted from the preset zero sequence current waveform through different algorithms, and the zero sequence current transient component amplitude is recorded as
The zero sequence current steady component amplitude is recorded as
The sampling time of the Prony algorithm is shorter than that of the FFT algorithm, which means that the Prony algorithm can extract low-frequency content in a signal; the interval (resolution) between the frequencies calculated by the method is independent of the sampling time, and the resolution is very high; the calculation result contains an attenuation coefficient, which can be regarded as having a certain correspondence to the dynamic signal. The fourier transform is a linear operator, which is also a unitary operator if given the appropriate norm; the inverse of the fourier transform is easy to find and the form is very similar to the forward transform.
Further, step 101, before, further includes:
and (3) presetting a zero sequence current waveform in a power frequency cycle after a fault is collected at the outlet of each line by adopting a zero sequence current transformer to obtain a preset zero sequence current waveform.
The preset zero sequence current waveform is a waveform after a fault occurs and can be acquired by adopting a zero sequence current transformer, the preset power frequency cycle can be set according to actual conditions, the waveforms in 5 working cycles are selected in the embodiment of the application, and the power frequency is 50 Hz.
Specifically, in the case of a low-impedance ground fault of the resonant grounded system, the equivalent circuit thereof can refer to fig. 3. When the switch T1Closing, switch T2When disconnected, the circuit is a transient equivalent circuit, and when the switch T is turned on1Switch T2When closed, the circuit is a steady-state equivalent circuit, where uf(t) is a fault point virtual voltage source, the equivalent inductance L and the equivalent resistance R both contain zero mode and line mode information on two sides of the fault point, C0_j( j 1,2.. n-1) is the robust outgoing line to ground distributed capacitance, C0_nThe capacitance is distributed to the ground by the fault outgoing line,
is a point of failure virtual voltage source, RfIs a transition resistance, LpIs 3 times of arc suppression coil equivalent inductance.
And 102, calculating the ratio of the transient component amplitude of the zero-sequence current at the outlet of each line to the steady component amplitude of the zero-sequence current to obtain a transient-steady amplitude ratio.
Assuming that n lines are total, calculating the transient component amplitude of the zero sequence current corresponding to each line
With amplitude of steady-state component
Ratio k ofj(j ═ 1,2.., n-1, n), n transient steady state amplitude ratios can be obtained. According to the illustration of fig. 3, the amplitude of the transient component of the zero sequence current at the outlet of the healthy line
And zero sequence current steady state component amplitude
Can be expressed as:
wherein the content of the first and second substances,
A1＝-Ucosθ
A2＝(ω0Usinθ+Uδcosθ)/ωf
δ＝-R/(2L)
wherein, C0_jDistributing capacitance, U, to ground for sound line outletmIs the phase voltage amplitude, ω0At power frequency angular frequency, RfIs the transition resistance value, C is the system capacitance, theta is the phase angle obtained in the calculation process,
is the initial phase angle of the fault. Therefore, the ratio of the zero sequence current transient component amplitude to the zero sequence current steady-state component amplitude at the outlet of the healthy line is:
through ratio formula analysis, the ratio of the transient steady state amplitudes at the outlets of all healthy lines is equal after the lines have a grounding low-impedance grounding fault; and if the bus has a fault, the transient and steady state amplitude ratios at the outlets of all the lines are equal.
The fault is then the zero sequence current transient component amplitude at the n-th line outlet
And zero sequence current steady state component amplitude
Can be expressed as:
then, the transient steady state amplitude ratio at the n line outlet where the fault occurs can be expressed as:
there are again:
wherein v is the system detuning degree,
representing the capacitive current of the system when the neutral point is not grounded,
representing the arc suppression coil current.
The calculation can be carried out by combining the two formulas:
because the capacitance current of the resonance grounding system is larger, the outgoing line quantity is more, the capacitance to ground of a single line is generally not more than 40 percent of the capacitance to ground of the system, namely
And because the detuning degree of the resonance grounding system meets the following requirements:
-10％≤ν≤-5％
therefore, the ratio of the amplitude of the faulty line to the amplitude of the healthy line needs to satisfy:
according to the above analysis, if the bus has a low-impedance ground fault, the amplitude ratios of all the lines are theoretically equal, and if the lines have a low-impedance ground fault, the amplitude ratios of the sound lines are equal, and the ratio of the fault line is greater than the ratio of the coil line, and the ratio of the two is greater than 1.2.
And 103, sorting all the transient and steady state amplitude ratios based on a bubble sorting algorithm, and calculating the ratio of the maximum transient and steady state amplitude ratio to the minimum transient and steady state amplitude ratio to obtain the maximum ratio.
Further, step 103 includes:
after numbering all the transient and steady state amplitude ratios, comparing the transient and steady state amplitude ratios in pairs based on a bubble sorting algorithm according to the numbers, and placing a smaller transient and steady state amplitude ratio behind a larger transient and steady state amplitude ratio to obtain the transient and steady state amplitude ratios in descending order;
obtaining a maximum transient steady state amplitude ratio and a minimum transient steady state amplitude ratio from the transient steady state amplitude ratios in descending order;
and calculating the ratio of the maximum transient steady-state amplitude ratio to the minimum transient steady-state amplitude ratio to obtain the maximum ratio.
The analysis process for determining the fault according to the above ratio can be performed firstAnd sequencing the obtained transient and steady state amplitude ratios of all the lines, and finding out the maximum value and the minimum value. The bubble sorting algorithm is used for comparing every two of all the number values, and continuously placing smaller values after larger values to finally obtain a descending sequence, wherein the first value at the top is the largest transient and steady state amplitude ratio kmaxThe last one is the minimum transient steady state amplitude ratio kmin. Concretely, k is firstlynAnd kn-1Comparing, and if the reverse order occurs, exchanging; otherwise compare kn-1And k isn-2Until comparison k2And k is1After the first pass, the lowest value is moved to the bottom, and k is sequentially shifted as in the first passnAnd kn-1Making a comparison until k3And k2After the second pass is completed, the next smallest value is moved to the second cell, and the process continues, one pass after the next, with the final lowest number being kminThe uppermost number is kmax。
And 104, if the maximum ratio is within a preset range, judging that the bus has single-phase earth fault, otherwise, judging that the line corresponding to the maximum transient and steady-state amplitude ratio has single-phase earth fault.
If so:
the maximum ratio is considered to be within a preset range, and a single-phase earth fault occurs to the bus; otherwise, judging the maximum transient and steady state amplitude ratio kmaxThe corresponding line has a single-phase earth fault.
For the convenience of understanding, Matlab/Simulink is adopted to build a ground fault simulation model of the resonant grounding system, and the ground fault simulation model is specifically shown in FIG. 4. The system has 6 lines (L)1-L6). Wherein the line L1-L3The system is an overhead line, and the lengths of the overhead line are 20km, 17km and 12km respectively; line L4The cable-overhead line hybrid line is composed of a 3km cable and a 10km overhead line; l is5-L6Is a cable with a length of 5km and 9 km. The system operates in an overcompensation mode, the inductance of the arc suppression coil is 0.6H, the overcompensation degree is 10%, and 1MW constant impedance loads are uniformly adopted at the tail ends of all the lines. f. of1、f2、f3Respectively represent the lines L1A single-phase earth fault and a line L occur at a distance of 5km from the bus5And a single-phase earth fault occurs at a position 3km away from the bus, and a single-phase earth fault occurs at the bus.
The positive/negative sequence impedance of the overhead line is (0.17+ j0.319) omega/km, and the positive/negative sequence admittance is j36.11 mu s/km; the zero sequence impedance is (0.32+ j1.118) omega/km, and the zero sequence admittance is j1.947 mu s/km. The positive/negative sequence impedance of the cable line is (0.27+ j0.08) omega/km, and the positive/negative sequence admittance is j118 mu s/km; the zero sequence impedance is (2.7+ j0.348) omega/km, and the zero sequence admittance is j86.664 mu s/km.
Please refer to table 1, which shows the zero sequence current transient/steady component amplitudes at the line outlets at different fault positions and transition resistances obtained by simulation.
TABLE 1 zero sequence current transient/steady state component amplitude at each line outlet under different fault conditions
Table 2 shows the transient steady state amplitude ratio and the ground fault line selection results for each line in table 1.
TABLE 2 the most significant ratio and line selection result of each outgoing line under different fault conditions
It can be seen from table 2 that, when the line of the resonant grounding system has a ground fault at different fault positions and at different fault resistances, the line is grounded
When a single-phase ground fault occurs on the bus of the resonant grounding system,
referring to fig. 5 and 6, fig. 5 shows waveforms of transient current and steady-state current of each outgoing line when the fault resistance is 10 Ω and the bus has a single-phase ground fault; FIG. 6 shows a fault resistance of 50 Ω, L5Each outlet transient current and steady state current waveform when single-phase earth fault occurs, wherein i0_L1、i0_L2、i0_L3、i0_L4、i0_L5、i0_L6Respectively represent the lines L1Line L2Line L3Line L4Line L5Line L6And zero sequence current is at the outlet. Line L in FIG. 64And a line L6The CT polarities are all connected in a reverse mode, correct line selection is not influenced, and the method can be proved to have no dependence on the CT polarities and to be higher in reliability.
According to the single-phase earth fault detection method of the resonant grounding system, fault analysis can be performed only by the aid of zero-sequence current waveforms at the line outlet, amplitude ratios of zero-sequence current components are mainly calculated in the analysis process, fault detection can be achieved without depending on CT polarity and other various data information, bus faults or other line faults can be determined, and the method is simple to operate and easy to implement. Therefore, the technical problem that in the prior art, dependence on CT polarity and various data information is large, and actual operation is limited can be solved.
For ease of understanding, referring to fig. 2, the present application provides an embodiment of a single-phase ground fault detection apparatus for a resonant grounding system, comprising:
an extracting module 201, configured to extract a zero-sequence current transient component amplitude and a zero-sequence current steady-state component amplitude from a preset zero-sequence current waveform at an outlet of each line;
the first calculation module 202 is configured to calculate a ratio between a zero-sequence current transient component amplitude and a zero-sequence current steady-state component amplitude at an outlet of each line, so as to obtain a transient-state amplitude ratio;
the second calculation module 203 is configured to calculate a ratio between the maximum transient steady-state amplitude ratio and the minimum transient steady-state amplitude ratio after sorting all transient steady-state amplitude ratios based on a bubble sorting algorithm, so as to obtain a maximum ratio;
the determining module 204 is configured to determine that a single-phase ground fault occurs on the bus if the maximum ratio is within a preset range, and otherwise determine that a single-phase ground fault occurs on a line corresponding to the maximum transient-steady-state amplitude ratio.
Further, still include:
the acquisition module 205 is configured to acquire a zero-sequence current waveform in a preset power frequency cycle after a fault occurs at an outlet of each line by using a zero-sequence current transformer, so as to obtain a preset zero-sequence current waveform.
Further, the extraction module 201 is specifically configured to:
extracting a zero sequence current transient component amplitude value from a preset zero sequence current waveform at an outlet of each line according to a preset Prony algorithm;
and extracting the zero-sequence current steady-state component amplitude from the preset zero-sequence current waveform at the outlet of each line by adopting a Fourier transform algorithm.
Further, the second calculating module 203 includes:
the sorting submodule 2031 is configured to number all the transient and steady-state amplitude ratios, compare every two transient and steady-state amplitude ratios with each other according to the numbers based on a bubble sorting algorithm, and place a smaller transient and steady-state amplitude ratio behind a larger transient and steady-state amplitude ratio to obtain a descending transient and steady-state amplitude ratio;
an obtaining sub-module 2032, configured to obtain a maximum transient steady-state amplitude ratio and a minimum transient steady-state amplitude ratio from the descending order of transient steady-state amplitude ratios;
the calculating submodule 2033 is configured to calculate a ratio between the maximum transient steady-state amplitude ratio and the minimum transient steady-state amplitude ratio, and obtain a maximum ratio.
The application also provides single-phase earth fault detection equipment of the resonance earthing system, which comprises a processor and a memory;
the memory is used for storing the program codes and transmitting the program codes to the processor;
the processor is configured to execute the single-phase ground fault detection method of the resonant grounding system in the above-described method embodiment according to instructions in the program code.
The present application further provides a computer-readable storage medium for storing program code for executing the resonant grounding system single-phase ground fault detection method in the above-mentioned method embodiments.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for executing all or part of the steps of the method described in the embodiments of the present application through a computer device (which may be a personal computer, a server, or a network device). And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A single-phase earth fault detection method of a resonance grounding system is characterized by comprising the following steps:
extracting a zero sequence current transient component amplitude value and a zero sequence current steady-state component amplitude value from a preset zero sequence current waveform at an outlet of each line;
calculating the ratio of the zero sequence current transient component amplitude to the zero sequence current steady-state component amplitude at the outlet of each line to obtain a transient steady-state amplitude ratio;
sorting all the transient and steady state amplitude ratios based on a bubble sorting algorithm, and calculating the ratio of the maximum transient and steady state amplitude ratio to the minimum transient and steady state amplitude ratio to obtain the most significant ratio;
and if the maximum ratio is within a preset range, judging that the bus has single-phase earth fault, otherwise, judging that the line corresponding to the maximum transient and steady-state amplitude ratio has single-phase earth fault.
2. The single-phase ground fault detection method of the resonant grounding system according to claim 1, wherein the zero sequence current transient component amplitude value and the zero sequence current steady-state component amplitude value are extracted from the preset zero sequence current waveform at the outlet of each line, and the method further comprises the following steps:
and (3) presetting a zero sequence current waveform in a power frequency cycle after a fault is collected at the outlet of each line by adopting a zero sequence current transformer to obtain a preset zero sequence current waveform.
3. The single-phase ground fault detection method of claim 1, wherein the extracting zero sequence current transient component amplitude values and zero sequence current steady-state component amplitude values from the preset zero sequence current waveform at the outlet of each line comprises:
extracting a zero sequence current transient component amplitude value from a preset zero sequence current waveform at an outlet of each line according to a preset Prony algorithm;
and extracting the zero-sequence current steady-state component amplitude from the preset zero-sequence current waveform at the outlet of each line by adopting a Fourier transform algorithm.
4. The method for detecting the single-phase ground fault of the resonant grounding system according to claim 1, wherein after all the transient steady-state amplitude ratios are sorted based on a bubble sorting algorithm, calculating a ratio of a maximum transient steady-state amplitude ratio to a minimum transient steady-state amplitude ratio to obtain a maximum ratio comprises:
after numbering all the transient and steady state amplitude ratio values, comparing the transient and steady state amplitude ratio values pairwise based on a bubble sorting algorithm according to numbers, and placing the smaller transient and steady state amplitude ratio value behind the larger transient and steady state amplitude ratio value to obtain the transient and steady state amplitude ratio values in descending order;
obtaining a maximum transient steady state amplitude ratio and a minimum transient steady state amplitude ratio from the transient steady state amplitude ratios in descending order;
and calculating the ratio of the maximum transient steady-state amplitude ratio to the minimum transient steady-state amplitude ratio to obtain the maximum ratio.
5. A single-phase ground fault detection device for a resonant grounding system, comprising:
the extraction module is used for extracting a zero sequence current transient component amplitude value and a zero sequence current steady-state component amplitude value from a preset zero sequence current waveform at the outlet of each line;
the first calculation module is used for calculating the ratio of the zero-sequence current transient component amplitude value to the zero-sequence current steady-state component amplitude value at the outlet of each line to obtain a transient-state amplitude ratio;
the second calculation module is used for calculating the ratio of the maximum transient steady-state amplitude ratio to the minimum transient steady-state amplitude ratio to obtain the most significant ratio after sequencing all the transient steady-state amplitude ratios based on a bubble sequencing algorithm;
and the judging module is used for judging that the bus has single-phase earth faults if the maximum ratio is within a preset range, and otherwise, judging that the line corresponding to the maximum transient and steady-state amplitude ratio has single-phase earth faults.
6. The single-phase ground fault detection device of claim 5, further comprising:
and the acquisition module is used for acquiring a zero sequence current waveform in a preset power frequency cycle after a fault occurs at the outlet of each line by adopting a zero sequence current transformer to obtain a preset zero sequence current waveform.
7. The single-phase ground fault detection device of a resonant grounding system according to claim 5, wherein the extraction module is specifically configured to:
extracting a zero sequence current transient component amplitude value from a preset zero sequence current waveform at an outlet of each line according to a preset Prony algorithm;
and extracting the zero-sequence current steady-state component amplitude from the preset zero-sequence current waveform at the outlet of each line by adopting a Fourier transform algorithm.
8. The apparatus according to claim 5, wherein the second computing module comprises:
the sorting submodule is used for numbering all the transient and steady state amplitude ratios, comparing every two transient and steady state amplitude ratios based on a bubble sorting algorithm according to numbers, and placing the smaller transient and steady state amplitude ratio behind the larger transient and steady state amplitude ratio to obtain the transient and steady state amplitude ratios in descending order;
the obtaining submodule is used for obtaining a maximum transient steady state amplitude ratio and a minimum transient steady state amplitude ratio from the transient steady state amplitude ratios in descending order;
and the calculation submodule is used for calculating the ratio of the maximum transient and steady state amplitude ratio to the minimum transient and steady state amplitude ratio to obtain the maximum ratio.
9. A resonant grounding system single-phase ground fault detection device, the device comprising a processor and a memory;
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the method of single-phase ground fault detection of a resonant grounding system according to any one of claims 1 to 4 according to instructions in the program code.
10. A computer-readable storage medium for storing program code for performing the method of single-phase ground fault detection of a resonant grounding system of any one of claims 1-4.
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