CN110954743A - Distributed wave recording device and low-current grounding line selection method - Google Patents
Distributed wave recording device and low-current grounding line selection method Download PDFInfo
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
Abstract
The utility model provides a distributed wave recording device and undercurrent ground connection route selection method, the wave form of PT/CT output is handled through direct sampling hardware circuit and high frequency band-pass sampling hardware circuit respectively, the wave form after handling is sent into AD and is sampled, handle the signal of direct sampling circuit and high frequency band-pass sampling circuit respectively, the digital signal of direct sampling circuit is after the sampling, calculate through quadrature integral algorithm, obtain real part, imaginary part and direct current part, the sampling signal of high frequency band-pass sampling circuit hardware circuit is handled through band-limiting filter, zero sequence signal still need calculate the imaginary part and the real part of multiple harmonic. The signal processing is also carried out through an impact filter and a peak value filter; and preprocessing the calculation result through the overvoltage and current data in the management unit, respectively calculating the grounding probability of the feeder line and the bus, and finally obtaining a line selection result. The method solves the problem of judging the single-phase grounding high-resistance fault in the states of no grounding, grounding through an arc suppression coil and grounding through a small resistor.
Description
Technical Field
The disclosure belongs to the technical field of power system monitoring, and relates to a distributed wave recording device and a low-current grounding line selection method.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
A single-phase grounding fault in a 6-35 kV medium-voltage power distribution network is the fault type which occurs most frequently. After a single-phase earth fault, the system is allowed to no longer exceed 2 hours at the maximum. The amplitude and the phase of the line voltage are not influenced, and the operation of equipment such as a motor and the like is not influenced. However, the non-fault phase voltage is easy to rise after long-time operation, and the weak insulation link is easy to break down, so that short-circuit fault is caused. The fault point generates electric arc, which can burn equipment and easily develop into the problems of interphase short circuit and the like. And therefore needs to be handled as soon as possible. However, the existing 6-35 kV system feeder line protection has the problems that zero sequence protection cannot be used, the grounding line selection accuracy is not high, and the like, and faults are still removed by using a pull method or experience in many fields at present.
The existing line selection device mostly adopts a centralized design, and the line selection method is also applied on the basis. The method is based on the theory that zero sequence current of a fault line is the sum of non-fault lines, but the principle is based on the steady-state amplitude of the zero sequence current, the grounding current is small, the grounding current is a soft rib of grounding line selection and is easily influenced by the external factors such as three-phase imbalance, and the like, so that the device based on the steady-state quantity can not accurately select the line all the time. With the richness of electronic technology and line selection theory, the transient-state-method-based small-current grounding line selection becomes the mainstream, and the line selection is mainly achieved by using the obvious transient characteristic quantity of 3-5ms existing at the moment of grounding, when a grounding fault occurs, the transient zero-sequence current of a fault line flows to a bus, the transient zero-sequence current of a non-fault line flows out of the bus, and the phase difference of the transient zero-sequence current is 180 degrees. At present, the mainstream low-current grounding line selection is basically based on the principle, and the grounding line selection is sensitive and the line selection rate is high. However, the algorithm is greatly affected by the transition resistance, and when special conditions such as high-resistance fault occur, the signal characteristic quantity is not obvious, and a line selection error can be caused.
Disclosure of Invention
The present disclosure provides a distributed wave recording device and a low-current grounding line selection method to solve the above problems, and the present disclosure can solve the determination problem of single-phase grounding high-resistance fault in the states of no grounding, grounding through an arc suppression coil, and grounding with a small resistor.
According to some embodiments, the following technical scheme is adopted in the disclosure:
the utility model provides a distributed wave recording device, includes administrative unit and a plurality of collection terminal, and every collection terminal includes PT CT to and filter circuit, AD converting circuit and treater, wherein:
the PT/CT is used for collecting A/B/C/zero sequence voltage or current;
the filter circuit is configured to perform low-pass filtering and high-frequency band-pass filtering on the collected voltage or current respectively;
the A/D conversion circuit is configured to perform AD conversion on the filtered signals, the converted digital signals enter a processor, and the processor is configured to perform fundamental wave quadrature integration on the low-pass filtered signals and calculate a real part, an imaginary part and a direct current part; performing band-limited filtering processing on the sampling signal subjected to the high-frequency band-pass filtering action, calculating quadrature integral of multiple harmonics for a zero-sequence signal, and calculating an imaginary part and a real part;
calculating sampling waveforms by taking the cycle as a unit, and transmitting the sampling waveforms to a management unit through an optical fiber for further processing;
the management unit is configured to process data by adopting a cross-correlation signal processing algorithm of orthogonal integral transformation to obtain an impact phase relation between bus voltage and feeder current, and further determine fault location and line selection.
As a further limitation, the filter circuit comprises a low-pass filter circuit and a high-frequency band-pass sampling circuit, wherein the low-pass filter circuit filters high-frequency signals and sends fundamental wave signals to the a/D conversion circuit; the high frequency band-pass sampling hardware circuit attenuates fundamental wave signals and generates gain for high frequency signals.
By way of further limitation, the management unit implements phase shift calculations by shifting a fixed number of points.
As a further limitation, the management unit is configured to calculate a feeder voltage and a bus voltage, determine a feeder grounding probability and a bus grounding probability according to a zero sequence current of a faulty line and a zero sequence current transient wave head phase deviation of a non-faulty line, and further perform feeder fault line selection by using a relation between a high frequency voltage and a high frequency current.
As a further limitation, when the neutral point is an arc suppression coil for a feeder fault, the phase of the grounding feeder and the phase of the non-grounding feeder are different by 180 degrees, and the phase of the grounding feeder and the non-grounding feeder are different by +90 degrees and-90 degrees respectively from the impulse voltage, and when the impulse voltage is moved to 90 degrees and is in the same phase with the impulse current of the grounding feeder during calculation, the grounding feeder is separated.
For feeder fault, when the neutral point is small resistance, the grounding feeder current is in phase with the voltage, but the grounding feeder current is 90 degrees different from the voltage, and at the moment, the high-frequency impulse voltage can complete quadrature calculation without moving the phase
As a further limitation, for a bus fault, no matter whether the neutral point is an arc suppression coil or a small resistor, the phase of the zero-sequence high-frequency impact voltage is 90 degrees different from the zero-sequence high-frequency impact current, the impact voltage is 0 degrees, the impact current is-90 degrees, the energy utilization maximization can be realized by being in phase with the impact current, the phases of two maximum impact energy feeder lines are calculated by processing the phase, the deviation of the two maximum impact energy feeder lines is less than 90 degrees for the arc suppression coil, and the deviation of the two maximum impact energy feeder lines is less than 45 degrees for the small resistor.
A small current grounding line selection method based on the device comprises the following steps:
collecting A/B/C/zero sequence voltage or current of each branch circuit;
respectively performing low-pass filtering and high-frequency band-pass filtering on the acquired voltage or current;
performing AD conversion on the filtered signals, performing fundamental wave quadrature integration on the low-pass filtered signals, and calculating a real part, an imaginary part and a direct current part; performing band-limited filtering processing on the sampling signal subjected to the high-frequency band-pass filtering action, calculating quadrature integral of multiple harmonics for a zero-sequence signal, and calculating an imaginary part and a real part;
calculating sampling waveforms by taking the cycle as a unit, processing data by adopting a cross-correlation signal processing algorithm of orthogonal integral transformation to obtain an impact phase relation between bus voltage and feeder current, calculating the feeder voltage and the bus voltage, determining the feeder grounding probability and the bus grounding probability according to the phase deviation of a zero-sequence current of a fault line and a zero-sequence current transient wave head of a non-fault line, and further performing feeder fault line selection by utilizing the relation between high-frequency voltage and high-frequency current.
Compared with the prior art, the beneficial effect of this disclosure is:
the method adopts a high-frequency characteristic quantity algorithm to process data, and can solve the problem of judging the single-phase grounding high-resistance fault in the states of no grounding, grounding through an arc suppression coil and grounding through a small resistor.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
FIG. 1 is a schematic flow diagram of the present disclosure;
FIG. 2 shows the phase voltage and line voltage conditions at fault for this embodiment;
FIG. 3 is a schematic diagram of the trip process of the present embodiment;
FIG. 4 is a power frequency fault waveform of the present embodiment;
fig. 5 is a high-frequency characteristic quantity fault waveform of the present embodiment;
fig. 6 is a line selection result of the present embodiment.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
A low-current grounding line selection method of a distributed wave recording device comprises the steps that the waveform output by PT/CT is processed by a direct sampling hardware circuit and a high-frequency band-pass sampling hardware circuit respectively, the processed waveform is sent into AD for sampling, and then calculation is carried out in an FPGA (field programmable gate array) of an acquisition terminal. Signals of a direct sampling circuit and a high-frequency band-pass sampling circuit are respectively processed in an FPGA (field programmable gate array), digital signals of the direct sampling circuit are sampled and then calculated through an orthogonal integration algorithm to obtain a real part, an imaginary part and a direct current part, sampling signals of a hardware circuit of the high-frequency band-pass sampling circuit are processed through a band-limiting filter, and the imaginary part and the real part of 3, 5 and 7-order harmonics are calculated for zero-sequence signals. The signal processing is also carried out through an impact filter and a peak value filter; after receiving the data sent by each acquisition terminal, the management unit processes the data by adopting a cross-correlation signal processing algorithm of orthogonal integral transformation. And preprocessing the calculation result through the overvoltage and current data in the management unit, respectively calculating the grounding probability of the feeder line and the bus, and finally obtaining a line selection result. The invention solves the problem of judging the single-phase grounding high-resistance fault in the states of no grounding, grounding through an arc suppression coil and grounding through a small resistor.
Specifically, fig. 1 is a flowchart of an implementation, and the implementation process is as follows:
firstly, in an acquisition terminal, signals accessed with A/B/C/zero sequence voltage (or current) are respectively accessed with a direct sampling hardware circuit and a high-frequency band-pass sampling hardware circuit after passing through PT (or CT). The direct sampling hardware circuit is a 5kHz low-pass filter circuit and is mainly used for filtering high-frequency signals and sending fundamental wave signals into the AD. The high-frequency band-pass sampling hardware circuit is a 130Hz high-frequency band-pass filter circuit, and mainly has the functions of generating 40dB attenuation on fundamental wave signals and generating 20dB gain on the high-frequency signals in order to improve the dynamic range of the system.
And after the power frequency signal and the high-frequency signal are processed, the AD chip performs AD conversion, and the converted digital signal is processed in the next step in the FPGA of the acquisition terminal.
The signals of the direct sampling circuit and the high-frequency band-pass sampling circuit are respectively processed in the FPGA, the digital signals of the direct sampling circuit are sampled at 10kHz and then the real part, the imaginary part and the direct current part are calculated through fundamental wave quadrature integration, and the calculation formula is as follows:
the sampling signal of the high-frequency band-pass sampling circuit is processed by a 5-order band-limiting filter with 192.3Hz as the center frequency.
The zero sequence signal of the high-frequency band-pass sampling circuit also needs to calculate quadrature integrals of 3, 5 and 7 harmonics, and calculate an imaginary part and a real part. Signal processing is also performed through the impulse filter and the peak filter.
And finally, the FPGA of the acquisition terminal calculates sampling waveforms including effective values, direct-current components, decision values and the like of all channels by taking the cycle as a unit, and transmits the sampling waveforms to the management unit through the optical fiber for further processing.
After receiving the data sent by each acquisition terminal, the management unit processes the data by adopting a cross-correlation signal processing algorithm of orthogonal integral transformation. The algorithm can keep limited phase deviation within a certain time while inhibiting noise interference, can fully utilize the energy of signals, particularly process weak signals applying Gaussian noise, can remarkably increase the signal-to-noise ratio, and enables the output signal-to-noise ratio of the system to be maximum at the moment of judgment.
Wherein V and I are the quadrature integral calculation results of zero sequence voltage and zero sequence current sent by the acquisition terminal respectively, and m is the phase shift to be adjusted.
Because the impact phase relation of the bus voltage and the feeder current reflects the fault state, the analysis of the fault data can be completed by using the bus voltage and the feeder current to carry out related calculation. In order to keep the algorithm used sufficiently suppressing the interference,
in the calculation, for the decision items needing to be selected, the corresponding 2-point product data keeps 0 degree or 180 degrees, and the other items keep about 90-degree phase difference as far as possible, so that decision separation can be processed more easily.
For feeder fault, when neutral point is arc suppression coil, the phase difference between grounding feeder and non-grounding feeder is 180 deg, and the phase difference between the grounding feeder and impulse voltage is +90 deg and-90 deg, respectively, and when the impulse voltage is moved to 90 deg and is in the same phase with impulse current of grounding feeder, the grounding feeder can be separated easily. When the neutral point is a small resistor, the current of the grounding feeder is in phase with the voltage, but the current of the grounding feeder is 90 degrees different from the voltage, and at the moment, the high-frequency impulse voltage can complete the orthogonal calculation without moving the phase.
For a bus fault, no matter whether a neutral point is an arc suppression coil or a small resistor, the phase of the zero-sequence high-frequency impact voltage is different from that of the zero-sequence high-frequency impact current by 90 degrees, the impact voltage is 0 degree, and the impact current is-90 degrees. Bus bar processing can be merged. The maximum energy utilization can be realized by the same phase as the impact current, the phase of the two maximum impact energy feeders can be calculated by processing the maximum impact energy feeders, the deviation of the maximum impact energy feeders is smaller than 90 degrees for the arc suppression coil, and the deviation of the maximum impact energy feeders is smaller than 45 degrees for the small resistor.
The analysis shows that the orthogonal algorithm sometimes needs to realize 90-degree phase shift of signals, and the algorithm adopts a method of moving fixed points to realize phase shift calculation. When the sampling frequency is 10KHz, the number of points required for the phase shift of the center frequency by 90 degrees is as follows:
the number of the selected calculation points corresponds to about 104 points with a center frequency of 2 cycles, and the length of the buffer area is 104+ 13-117.
Starting buffering data:
the specific algorithm for grounding and route selection in the management unit is as follows:
1. voltage and current data preprocessing
The surge voltage and the surge current are respectively expressed as follows:
impulse voltage: sv(0)，sv(1)，sv(2)，…，sv(n-1)；
Impact current:
feeder line 0 ═ si(0，0)，si(0，1)，si(0，2)，…，si(0，(n-1；
:
The feeder line k is si(k，0)，si(k，1)，si(k，2)，…，si(k，(n-1；
1) Neutral point is not grounded and the arc suppression coil is grounded:
calculating voltage by a feeder line: v. ofFeeder(n)＝v(n+13)；
Wherein n is 0, 1, 2, …, 103;
calculating voltage of the bus: v. ofbus(n)＝-v(n+13)；
Wherein n is 0, 1, 2, …, 103;
2) neutral point small resistance grounding:
calculating voltage by a feeder line: v. ofFeeder(n)＝v(n)；
Wherein n is 0, 1, 2, …, 103;
calculating voltage of the bus: v. ofbus(n)＝-v(n+13)；
Wherein n is 0, 1, 2, …, 103;
3) calculating voltage energy:
since the calculated voltage starting points may be different, the feeder voltage energy and the bus voltage energy are calculated separately.
Feeder voltage energy:
bus voltage energy:
2. feed line grounding probability calculation
1) Calculating the current energy of the feeder:
k feeder current energy:
2) calculate V.I dot product:
k feeder lines:
3) the grounding probability of the independent feeder line:
4) merging the feeder line grounding probability:
wherein: m is the number of feeders of the current bus.
3. Bus grounding probability calculation
1) And the vector current flowing through the bus:
sampling point n:
2) the absolute value current flowing through the bus:
sampling point n:
3) voltage dot product vector current:
4) absolute value current energy:
5) bus grounding probability:
in order to better explain the method of the invention, the actual fault waveform and the line selection result of a certain field are explained, and the specific steps are as follows:
a certain transformer substation is an ungrounded system, the voltage threshold is started to be set to be 25V, 5 feeders are provided in total, the trip time is set to be 8s, a fault of 6, month and 16 days in 2018 is selected, the fault is non-metal grounding, the fault starting time is 10:19:56, the system records the conditions of phase voltage and line voltage when the fault occurs as shown in figure 2, and the fault lasts for 10 times after exceeding 8 s: 20:04 trip success the system returns after 10:20:05 detects the failure disappears as shown in FIG. 3.
Fig. 4 is a power frequency fault waveform, which can record 24 cycles of waveforms before and after 6 cycles of voltage and current faults, and the recording data includes three-phase voltage, zero-sequence voltage and zero-sequence current of each feeder line.
As can be seen from fig. 4, the phase difference between the zero sequence current of the faulty line and the zero sequence current transient wave head of the non-faulty line is 180 degrees, the phase difference between the same steady-state current is also 180 degrees, the zero sequence current of the non-faulty line leads the zero sequence voltage by 90 degrees, and the zero sequence current of the faulty line lags the zero sequence voltage by 90 degrees, which meets the characteristics of the ungrounded system.
Fig. 5 is a high frequency characteristic quantity fault waveform, and similarly records a waveform of 24 cycles after a fault 6 cycles before the fault.
From the waveforms, even if the zero-sequence current of the transient high-frequency characteristic quantity is opposite to the zero-sequence current of the non-fault line, the relation that the zero-sequence voltage leads the zero-sequence current of the fault line by 90 degrees and lags the zero-sequence current of the non-fault line by 90 degrees can be obtained. The fault line selection of the two feeder lines of the system can be realized by utilizing the relation between high-frequency voltage and high-frequency current.
Fig. 6 shows the calculated line selection result, i.e. 1014 lines are provided as the ground feeding lines.
In summary, the low-current grounding line selection method of the distributed wave recording device adopts a high-frequency characteristic quantity algorithm. The method can solve the problem of judging the single-phase grounding high-resistance fault in the states of no grounding, grounding through an arc suppression coil and grounding through a small resistor.
As will be appreciated by one skilled in the art, embodiments of the present disclosure may be provided as a method, system, or computer program product. Accordingly, the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein.
The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (8)
1. The utility model provides a distributed wave recording device which characterized by: including administrative unit and a plurality of collection terminal, every collection terminal includes PT CT to and filter circuit, AD converting circuit and treater, wherein:
the PT/CT is used for collecting A/B/C/zero sequence voltage or current;
the filter circuit is configured to perform low-pass filtering and high-frequency band-pass filtering on the collected voltage or current respectively;
the A/D conversion circuit is configured to perform AD conversion on the filtered signals, the converted digital signals enter a processor, and the processor is configured to perform fundamental wave quadrature integration on the low-pass filtered signals and calculate a real part, an imaginary part and a direct current part; performing band-limited filtering processing on the sampling signal subjected to the high-frequency band-pass filtering action, calculating quadrature integral of multiple harmonics for a zero-sequence signal, and calculating an imaginary part and a real part;
calculating sampling waveforms by taking the cycle as a unit, and transmitting the sampling waveforms to a management unit through an optical fiber for further processing;
the management unit is configured to process data by adopting a cross-correlation signal processing algorithm of orthogonal integral transformation to obtain an impact phase relation between bus voltage and feeder current, and further determine fault location and line selection.
2. The distributed wave recording apparatus of claim 1, wherein: the filter circuit comprises a low-pass filter circuit and a high-frequency band-pass sampling circuit, wherein the low-pass filter circuit filters high-frequency signals and sends fundamental wave signals to the A/D conversion circuit; the high frequency band-pass sampling hardware circuit attenuates fundamental wave signals and generates gain for high frequency signals.
3. The distributed wave recording apparatus of claim 1, wherein: the management unit realizes phase shift calculation by moving a fixed point number.
4. The distributed wave recording apparatus of claim 1, wherein: the management unit is configured to calculate feeder line voltage and bus line voltage, determine feeder line grounding probability and bus line grounding probability according to zero sequence current of a fault line and zero sequence current transient wave head phase deviation of a non-fault line, and further perform feeder line fault line selection by using the relation between high-frequency voltage and high-frequency current.
5. The distributed wave recording apparatus of claim 1, wherein: for feeder fault, when neutral point is arc suppression coil, the phase difference between grounding feeder and non-grounding feeder is 180 deg, and the phase difference between the grounding feeder and impulse voltage is +90 deg and-90 deg, respectively, and when the impulse voltage is moved to 90 deg and is in phase with impulse current of grounding feeder, the grounding feeder is separated.
6. The distributed wave recording apparatus of claim 1, wherein: for feeder faults, when the neutral point is a small resistor, the current of the grounding feeder is in phase with the voltage, but the current of the grounding feeder is 90 degrees different from the voltage, and at the moment, the high-frequency impulse voltage can complete quadrature calculation without phase shifting.
7. The distributed wave recording apparatus of claim 1, wherein: for a bus fault, no matter a neutral point is an arc suppression coil or a small resistor, the phase of zero sequence high-frequency impact voltage is 90 degrees different from zero sequence high-frequency impact current, the impact voltage is 0 degree, the impact current is-90 degrees, energy utilization maximization can be realized by the same phase with the impact current, the phases of two maximum impact energy feeder lines are calculated by processing the phase, the deviation of the arc suppression coil is smaller than 90 degrees, and the deviation of the small resistor is smaller than 45 degrees.
8. A low current grounding line selection method based on the device of any one of claims 1-7, characterized by: the method comprises the following steps:
collecting A/B/C/zero sequence voltage or current of each branch circuit;
respectively performing low-pass filtering and high-frequency band-pass filtering on the acquired voltage or current;
performing AD conversion on the filtered signals, performing fundamental wave quadrature integration on the low-pass filtered signals, and calculating a real part, an imaginary part and a direct current part; performing band-limited filtering processing on the sampling signal subjected to the high-frequency band-pass filtering action, calculating quadrature integral of multiple harmonics for a zero-sequence signal, and calculating an imaginary part and a real part;
calculating sampling waveforms by taking the cycle as a unit, processing data by adopting a cross-correlation signal processing algorithm of orthogonal integral transformation to obtain an impact phase relation between bus voltage and feeder current, calculating the feeder voltage and the bus voltage, determining the feeder grounding probability and the bus grounding probability according to the phase deviation of a zero-sequence current of a fault line and a zero-sequence current transient wave head of a non-fault line, and further performing feeder fault line selection by utilizing the relation between high-frequency voltage and high-frequency current.
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| CN112485716A (en) * | 2020-11-30 | 2021-03-12 | 云南电网有限责任公司电力科学研究院 | Line selection method based on zero-rest transient characteristic signal of ground fault arc current |
| CN112485714A (en) * | 2020-11-30 | 2021-03-12 | 云南电网有限责任公司电力科学研究院 | High-sensitivity ground fault detection and identification method and device |
| CN112485713A (en) * | 2020-11-30 | 2021-03-12 | 云南电网有限责任公司电力科学研究院 | Line selection device and method based on zero-break characteristic of ground fault current |
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