CN202486265U - Distribution network high-resistance single-phase earthing fault route selection device - Google Patents
Distribution network high-resistance single-phase earthing fault route selection device Download PDFInfo
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- CN202486265U CN202486265U CN2012201383341U CN201220138334U CN202486265U CN 202486265 U CN202486265 U CN 202486265U CN 2012201383341 U CN2012201383341 U CN 2012201383341U CN 201220138334 U CN201220138334 U CN 201220138334U CN 202486265 U CN202486265 U CN 202486265U
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Abstract
The utility model relates to a distribution network high-resistance single-phase earthing fault route selection device. The device consists of an alternating current sampling module, a fault data analysis and processing module, a human-machine module, a signal motherboard and a power module, wherein the alternating current sampling module, the human-machine module and the fault data analysis and processing module are respectively bidirectionally connected with the signal motherboard; and the power module is connected to the modules and supplies power. By using the distribution network high-resistance single-phase earthing fault route selection device provided by the utility model, a fault start point at the moment of distribution network single-phase earth fault can be accurately captured, and the difficult problem of capturing the fault start point at the time of single-phase high-resistance earthing is solved. The distribution network high-resistance single-phase earthing fault route selection device is sensitive and reliable, and can be applied to route selection in distribution network fault in which a neutral point is not earthed or not directly earthed.
Description
Technical field
The utility model relates to the electrical equipment technical field of electric system neutral point indirect earthing power distribution network, relates in particular to a kind of power distribution network high resistant single-phase earth fault line selection device.
Background technology
China's low-voltage network mostly adopts the neutral point indirect earthing mode; Single-phase earthing is the major failure form of operation of power networks in this type electrical network; Account for more than 60% of electrical network total failare, even most of phase fault also is to be formed by the singlephase earth fault development.When singlephase earth fault took place, system line voltage was still symmetrical, does not influence the normal power supply to the user, allowed to continue operation 1～2 hour by the rules requirement; At this moment, non-fault phase-to-ground voltage rises to the line voltage levvl, possibly cause its insulation weakness to take place to puncture over the ground; Thereby accident enlarges; Especially be main power distribution network with the cable, in a single day single-phase earthing takes place in cable, develops into nonvolatil alternate or three-phase fault more.Statistics according to electric system shows that high resistant resistance ground connection is modal single-phase earthing in the single-phase earthing, because of its malfunction complicacy; Drop in the thick grass like circuit broken string, on the stone, branch is hung and is bumped hi-line; Cable insulation is aging or the like, and its stake resistance variation range is big, and fault-signal is faint; Usually can't catch fault-signal and cause the erroneous judgement to fault, be the root that causes the line-selected earthing device erroneous judgement.
The theoretical great majority of route selection of at present domestic Small Electric Current Earthing And Routing Device in usefulness are based on steady-state signal route selection method; The startup method is the fixing threshold Starting mode of residual voltage normally; Specifically: when system under test (SUT) generation singlephase earth fault, can produce residual voltage, begin to start the route selection program when residual voltage surpasses prior setting value when line selection apparatus detects.Adopt fixedly threshold Starting mode of residual voltage, show from field operation experiences and data: system's fault initiating point when the resistive ground connection of single-phase height is taken place is caught inaccurate.Its basic reason is that the residual voltage that when faulty line takes place by the resistive ground connection of single-phase height, produces is very little; And it is a slow process that the voltage rising changes; Earth fault takes place in a flash; Residual voltage does not reach the fixing threshold value that starts, and when waiting until that the system zero sequence voltage has missed the best opportunity of catching the earth fault characteristic signal when reaching the voltage starting threshold value.Thereby missed the route selection Best Times, caused producing and falsely drop, thereby influence the route selection accuracy rate.
Summary of the invention
To above problem, the utility model provides a kind of power distribution network high resistant single-phase earth fault line selection device, and fault initiating point is caught inaccurate problem, raising route selection accuracy rate in the time of can solving in the existing route selection technology the resistive ground connection of single-phase height.
The realization technical scheme of the utility model is following:
A kind of power distribution network high resistant single-phase earth fault line selection device; Form by AC sampling module, failure data analyzing and processing module, man-machine module, signal motherboard and power module; Wherein AC sampling module, man-machine module, failure data analyzing and processing module respectively with the two-way binding of signal motherboard, power module connects each module also provides power supply.
Said AC sampling module is provided with 12 couples of signals collecting input port PT/CT; Wherein there are two pairs of signals to receive voltage signal from zero sequential potential transformer PT; 10 pairs of signals in addition receive the zero sequence current signal from zero sequence current mutual inductor CT; Each is to the corresponding AC converter of signals collecting input end; The signal that conversion is come out is delivered to mould/number A/D change-over circuit after handling through filtering circuit and operational amplification circuit, after mould/number A/D change-over circuit conversion, delivers to the on-site programmable gate array FPGA unit;
Said failure data analyzing and processing module are by CPU module, clock module, storage unit and include the communication serial ports; The communication module of Ethernet interface constitutes, and this failure data analyzing is connected with each AC sampling module and man-machine module with control bus through data bus with processing module;
Said man-machine module is made up of LCDs and keyboard;
Said signal motherboard is used for the signal transmission between CPU module and AC sampling module and the man-machine module;
Also has a power module to above-mentioned module for power supply.
The said scheme practical implementation of the utility model method may further comprise the steps:
(1) FPGA (Field-Programmable Gate Array: field programmable gate array) as the temporary core cell of controlling of sampling and data in the whole acquisition system; ADC (Analog to Digital Converter analog/digital converter) is implemented control; And temporarily preserve ADC through second order hardware bandpass filtering after zero-sequence current, the voltage digital signal into of adopting, thereby realize quick high accuracy real-time data acquisition to the distribution network system of being monitored.At last by MPU (Micro Processor Unit: the data that microprocessor unit) read the temporal data of FPGA and preserve preceding four cycles of current time.For the residual voltage signal, whenever adopt into a data points simultaneously, will itself and 1023 points having adopted before this into be calculated residual voltage signal fundamental frequency effective value through full-wave fourier algorithm.
(2) when distribution network system generation singlephase earth fault, line selection apparatus adopts residual voltage sudden change amount to start and the comprehensive start-up criterion of residual voltage amplitude, confirms the fault initial time.Comprehensive start-up criterion is specially:
Program detects the residual voltage last samples value calculating voltage sudden change amount that collects in real time; When residual voltage sudden change amount Δ u (n) satisfies: during Δ u (n)＞Utd; Number of times to satisfying sudden change amount condition is counted, and has only when continuously surpassing 3 times and just thinks reliable startup, calculates then and judges whether the residual voltage amplitude satisfies the amplitude entry condition; When residual voltage sampled value U0 (n) satisfies: during U0 (n)＞Ugd is the fault origination point, starts the route selection logic.
Wherein: n is the sampled point numbering; N is a power frequency cycle sampling number, N=1024 (i.e. the sample rate f s=51.2kHz of device); Δ u (n)=u (N)-2u (n-1N)+u (n-2N); Utd is a sudden change amount threshold, and Utd numerical value is defaulted as 2V, guarantees the sensitivity and the accuracy of program start.Ugd is a fixedly threshold of residual voltage, and Ugd numerical value is defaulted as 30V.
The beneficial effect of the utility model is:
Can capture the singlephase earth fault fault initiating point of moment exactly, the difficult problem that fault initiating point is caught when solving single-phase high resistance ground.Not only sensitivity but also reliable was applied in the distribution network fault line selection of isolated neutral or non_direct ground.
Description of drawings
Fig. 1 is the hardware structure diagram of the utility model;
Fig. 2 is that the protection of the utility model starts process flow diagram.；
Embodiment
Below in conjunction with accompanying drawing and embodiment the technical scheme of the utility model is described further.
As shown in Figure 1; The described a kind of power distribution network high resistant single-phase earth fault line selection device of the utility model; Form by power module 1, man-machine module 2, AC sampling module 3, signal motherboard 4 and failure data analyzing and processing module 5; Wherein AC sampling module, man-machine module, failure data analyzing and processing module respectively with the two-way binding of signal motherboard, power module connects each module also provides power supply.
Said AC sampling module 3 is provided with 12 couples of signals collecting input port PT/CT6, wherein has two pairs of signals to receive the voltage signal from zero sequential potential transformer PT, and 10 pairs of signals in addition receive the zero sequence current signal from zero sequence current mutual inductor CT.Each is to the corresponding AC converter of signals collecting input end, and the signal that conversion is come out is delivered to mould/number A/D change-over circuit 8 through filtering, operational amplification circuit 7 after handling, and after mould/number A/D change-over circuit 8 conversions, delivers to on-site programmable gate array FPGA 9;
Said failure data analyzing and processing module 5; By CPU module 10, clock module 11, storage unit 12 with include the communication serial ports; The communication module 13 of Ethernet interface constitutes, and this failure data analyzing is connected with man-machine module 2 with each AC sampling module 3 with control bus through data bus with processing module 5;
The said man-machine module 2 that constitutes by display and keyboard;
Said signal motherboard 4 is used for the signal transmission between CPU module 10 and AC sampling module 3 and the man-machine module 2;
Said power module 1 is to above-mentioned module for power supply;
Single solid line among Fig. 1 between the functional module is represented control signal, and single dotted line is represented external analog signal, and heavy line is represented address, data-signal, and arrow is represented the trend of these signals.
Fig. 2 is that the protection of the utility model starts process flow diagram, comprises following:
In step 101, from modulus converter A/D, read bus residual voltage and each circuit zero sequence current sampling data, and be placed among the buffer memory RAM of appointment;
In step 102, according to the residual voltage last samples value calculating voltage sudden change amount that collects, computing method are following:
Δu(n)＝u(N)-2u(n-1N)+u(n-2N)
In the formula (1), Δ u (n) expression sudden change value, u (N) expression residual voltage last samples value, the sampled value of u (n-1N) expression one all wavefront, the sampled value of u (n-2N) expression two all wavefront, N representes weekly ripple sampling point sample.Can more be clear that referring to Fig. 2; When electrical network generation singlephase earth fault, because residual voltage can become big suddenly, the therefore up-to-date sampled point u (N) that collects can become big suddenly; And sampled value u (n-1N) and u (n-2N) before the fault are basic identical, and Δ u (n) can represent the fault situation of change;
In step 103, judge whether the sudden change amount satisfies condition, sudden change amount threshold is set to 2V;
In step 104～106, the number of times that satisfies sudden change amount condition is counted, have only when surpassing 3 times continuously and just think reliable startup, can avoid like this causing error starting because of the disturbance factor of chance, improved the reliability of fault initiating;
In step 107, carry out the 20ms time-delay, guarantee that the fault data window satisfies a cycle, for starting, amplitude prepares;
In step 108, calculating also judges whether the residual voltage amplitude satisfies the amplitude entry condition, and generally speaking, behind the electrical network generation singlephase earth fault, residual voltage all can surpass 30V, therefore starts threshold with 30V as amplitude;
In step 109, start and the amplitude entry condition owing to satisfy the sudden change amount, judge therefore singlephase earth fault taken place that the fault initiating element is effective.
In step 110, start the route selection logic, judge ground path.
Claims (5)
1. power distribution network high resistant single-phase earth fault line selection device; It is characterized in that; This line selection apparatus is made up of AC sampling module, failure data analyzing and processing module, man-machine module, signal motherboard and power module; Wherein AC sampling module, man-machine module, failure data analyzing and processing module respectively with the two-way binding of signal motherboard, power module connects each module also provides power supply.
2. power distribution network high resistant single-phase earth fault line selection device according to claim 1; It is characterized in that; Said AC sampling module is provided with 12 couples of signals collecting input port PT/CT; Wherein have two pairs of signals to receive the voltage signal from zero sequential potential transformer PT, other 10 pairs of signals receive the zero sequence current signal from zero sequence current mutual inductor CT, and each is to the corresponding AC converter of signals collecting input end; The signal that conversion is come out is delivered to mould/number A/D converter after handling through wave filter and operational amplifier, after mould/number A/D converter conversion, delivers to the on-site programmable gate array FPGA unit.
3. power distribution network high resistant single-phase earth fault line selection device according to claim 1; It is characterized in that; Said failure data analyzing and processing module are by CPU module, clock module, storage unit and include the communication serial ports; The communication module of Ethernet interface constitutes, and this failure data analyzing is connected with man-machine module with each AC sampling module with control bus through data bus with processing module.
4. power distribution network high resistant single-phase earth fault line selection device according to claim 1 is characterized in that said man-machine module is made up of display and keyboard.
5. power distribution network high resistant single-phase earth fault line selection device according to claim 1 is characterized in that said signal motherboard is used for the signal transmission between CPU module and AC sampling module and the man-machine module.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2012201383341U CN202486265U (en) | 2012-04-03 | 2012-04-03 | Distribution network high-resistance single-phase earthing fault route selection device |
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| CN2012201383341U CN202486265U (en) | 2012-04-03 | 2012-04-03 | Distribution network high-resistance single-phase earthing fault route selection device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102608500A (en) * | 2012-04-03 | 2012-07-25 | 云南电网公司玉溪供电局 | High-resistance, single-phase ground fault line selection device for distribution networks and starting method thereof |
| CN108594071A (en) * | 2018-04-18 | 2018-09-28 | 广东电网有限责任公司 | A kind of single-phase earth fault detecting method of neutral grounding by small resistance distribution |
-
2012
- 2012-04-03 CN CN2012201383341U patent/CN202486265U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102608500A (en) * | 2012-04-03 | 2012-07-25 | 云南电网公司玉溪供电局 | High-resistance, single-phase ground fault line selection device for distribution networks and starting method thereof |
| CN108594071A (en) * | 2018-04-18 | 2018-09-28 | 广东电网有限责任公司 | A kind of single-phase earth fault detecting method of neutral grounding by small resistance distribution |
| CN108594071B (en) * | 2018-04-18 | 2020-09-25 | 广东电网有限责任公司 | Single-phase earth fault detection method for neutral point small-resistance earth distribution network |
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Granted publication date: 20121010 |
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