CN107765139A - A kind of resonant earthed system fault line selection method for single-phase-to-ground fault of high-accuracy - Google Patents
A kind of resonant earthed system fault line selection method for single-phase-to-ground fault of high-accuracy Download PDFInfo
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- CN107765139A CN107765139A CN201710843426.7A CN201710843426A CN107765139A CN 107765139 A CN107765139 A CN 107765139A CN 201710843426 A CN201710843426 A CN 201710843426A CN 107765139 A CN107765139 A CN 107765139A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- 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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
Abstract
The present invention relates to a kind of resonant earthed system fault line selection method for single-phase-to-ground fault of high-accuracy, including the steps：Fault moment is positioned, reads the zero-sequence current sampled data of 3 cycles after half of cycle and failure before each bar line fault；Row set empirical mode decomposition is entered to each road outlet zero-sequence current sampled data, calculate each 10Hz low-frequency ranges of road outlet Hilbert marginal spectrum 0, more than 250Hz high bands instantaneous energy and, select the maximum two lines road of energy as primary election circuit；Hilbert transform is made to first half-wave part after two primary election circuit intrinsic mode function IMF failure, calculate each IMF instantaneous frequency average value, select the high fdrequency component of IMF component reconstruct zero-sequence current of the instantaneous frequency average value higher than 250Hz, the high fdrequency component on two lines road is made into inner product, if inner product is negative, the maximum primary election circuit of energy is faulty line, if inner product is just, it is then bus-bar fault, exports route selection result, route selection terminates.
Description
Technical field
The invention belongs to relay protection, distribution network technology field.It is a kind of resonant earthed system having compared with high-accuracy
Fault line selection method for single-phase-to-ground fault.
Background technology
Resonant earthed system is mainly used in China's low and medium voltage distribution network.After singlephase earth fault occurs for resonant earthed system
Line voltage is still symmetrical, does not influence the power supply to user, and code regulation can operate with failure 1~2 hour, power supply reliability
It is high.
After singlephase earth fault occurs for resonant earthed system, because arc suppression coil generally uses overcompensation mode, fault wire
Road and non-fault line zero-sequence current feature differentiation unobvious, failure line selection are very difficult.
At present, domestic and foreign scholars propose many selection methods for resonant earthed system singlephase earth fault, conclude
Two classes can be divided into：Selection method based on steady-state signal and the selection method based on transient signal.Based on steady-state signal
Selection method generally use compares stable status zero-sequence current amplitude, the mode of phase determines faulty line, because fault-signal is faint,
Fault ground mode is changeable, and route selection result is unsatisfactory.Selection method generally use extraction transient signal based on transient signal
The information such as Sudden Changing Rate, amplitude, polarity, energy carry out failure line selection, and with the development of signal time frequency analyzing tool, transient state is believed in addition
Contain abundant fault message in number, the selection method based on transient signal emerges in an endless stream in recent years.It is existing to be believed based on transient state
Number selection method use transient signal high fdrequency component route selection more, use small echo, wavelet packet, empirical mode decomposition (EMD) etc. number
Method carries out data processing.But the amplitude of transient signal is affected by many factors, the high frequency division in the case of glitch switching angle
It is smaller to measure amplitude, can influence route selection accuracy using only high fdrequency component route selection.And the selection of wavelet basis function never has one
Individual clear and definite standard, the problem of EMD algorithms there may be modal overlap.
The content of the invention
The purpose of the present invention is to overcome the above-mentioned deficiency of prior art, there is provided a kind of resonance grounding having compared with high-accuracy
System single-phase earth fault route selecting method, technical scheme are as follows：
A kind of resonant earthed system fault line selection method for single-phase-to-ground fault of high-accuracy, the method include the steps：
(1) voltage transformer secondary side opening residual voltage is monitored, starts following failure when voltage exceedes threshold value
Route selection step；
(2) fault moment is positioned, the zero-sequence current for reading 3 cycles after half of cycle and failure before each bar line fault is adopted
Sample data；
(3) row set empirical mode decomposition (EEMD) is entered to each road outlet zero-sequence current sampled data, by signal decomposition into
Some intrinsic mode function IMF components and residual components, afterwards, Hilbert transform is carried out respectively to each layer IMF components and obtained
Relevant parameter, including instantaneous phase, instantaneous frequency and instantaneous amplitude, instantaneous amplitude square is obtained into instantaneous energy, by time, wink
When frequency, instantaneous energy composition hilbert spectrum, hilbert spectrum is obtained into Hilbert marginal spectrum to time integral, calculated each
Road outlet Hilbert marginal spectrum 0-10Hz low-frequency ranges, more than 250Hz high bands instantaneous energy and, select maximum two of energy
Circuit is as primary election circuit；
(4) Hilbert transform is made to first half-wave part after two primary election circuit intrinsic mode function IMF failure, calculated
Each IMF instantaneous frequency average value, select the height of IMF component reconstruct zero-sequence current of the instantaneous frequency average value higher than 250Hz
Frequency component, the high fdrequency component on two lines road is made into inner product, if inner product is negative, the maximum primary election circuit of energy is faulty line,
If inner product is just, for bus-bar fault, output route selection result, route selection terminates.
For the present invention due to taking above technical scheme, it has advantages below：
(1) new selection method employs EEMD decomposition methods in overall data process.EEMD can be adaptively by zero sequence
Current signal is decomposed into multiple intrinsic mode functions and extracted for fault characteristic, avoids Traditional Wavelet analytic approach route selection wavelet basis
The defects of the problem of function is not easy to choose and EMD methods there may be modal overlap.
(2) attenuating dc component and high fdrequency component are used for faulty line primary election simultaneously, reduce fault close angle to choosing
The influence of line accuracy.
(3) faulty line primary election can effectively filter out the non-faulting that transient state energy is low, amplitude is small using marginal spectrum energy method
Circuit；In outlet failure, faulty line primary election can effectively distinguish failure and non-fault line.
(4) high fdrequency component method can realize self-adapting reconstruction to the HFS of signal, and pole is carried out using high frequency reconstruction signal
Property compares, and enhances the amplitude of useful signal, ensure that the reliability of Polarity comparision.
Brief description of the drawings
Fig. 1 is resonant earthed system simulation model.
Fig. 2 is the route selection flow chart of the present invention.
L in Fig. 11、L2For overhead line, L3、L4For cable, L5For aerial cable blend, cable part is close to bus.
CT is current transformer, and PT is voltage transformer, and K is switch.
Embodiment
The present invention is described in detail with reference to the accompanying drawings and examples.
Resonant earthed system includes 5 tunnel outlet L by taking the simulation model shown in Fig. 1 as an example in figure1~L5, wherein L1、L2For
Overhead line, length are respectively 30km, 15km；L3、L4For cable, length is respectively 12km, 8km；L5Mixed for aerial cable
Line length 7km long 5km, is maked somebody a mere figurehead in line, cable part close to bus.Overhead transmission line, cable-line parameter are as shown in table 1.It is all negative
Lotus is loaded using three-phase series RLC.
The line parameter circuit value of table 1
Arc Suppression Coil Compensation Degree takes 8%, and system distribution capacity C over the ground is obtained by line parameter circuit valueΣ, and then calculate arc blowout wire
Enclose equivalent inductance L=1/1.08*1/ (3 ω2CΣ)=0.7559H.The active loss of arc suppression coil takes 3%, the R that perception is lostL=
0.03 ω L=7.1242 Ω.Sample frequency is 6.4kHz.
Example 1
Set outlet L1Singlephase earth fault, 0 ° of fault close angle, the Ω of transition resistance 10 are occurring at bus 3km.
Failure starts line selection algorithm after occurring, and reads before each road outlet failure zero of 3 cycles after half of cycle and failure
Sequence current sampling data.
Row set empirical mode decomposition (EEMD) is entered to each road outlet zero-sequence current sampled data first, by signal decomposition into
Some intrinsic mode function (IMF) components and residual components, to facilitate further extraction fault signature.
In formula：S (t) is primary signal；N is the quantity of IMF components；Ci(t) it is i-th layer of IMF component, wherein C0(t) it is surplus
Remaining component.Component of the intrinsic mode function representation signal of different layers in different time scales.
Afterwards, Hilbert transform is carried out respectively to each layer IMF components and obtains relevant parameter.
In formula：For instantaneous phase；fi(t) it is instantaneous frequency；ai(t) it is instantaneous amplitude.
Instantaneous energy corresponding to the different instantaneous frequencys of each intrinsic mode function (IMF) is further calculated on the basis of formula (3)
Value.Instantaneous energy value is：
Ei(t)=ai(t)2 (4)
Finally ask hilbert spectrum and Hilbert marginal spectrum.
Formula (5) is Hilbert spectrum, and abbreviation hilbert spectrum, it represents instantaneous amplitude in frequency-time plane
Distribution；Formula (6) is Hilbert marginal spectrum, and marginal spectrum is obtained by time-frequency spectrum to time integral.
Selected 0-10Hz low-frequency ranges, as characteristic spectra, are calculated in each road outlet characteristic spectra with more than 250Hz high bands
Marginal spectrum energy it is as shown in table 2.
The circuit limit spectrometry energy of table 2
As can be seen from Table 2, circuit L1And L3Energy is maximum, as primary election circuit.
Faulty line is determined below by high fdrequency component method.To primary election circuit L1And L3First the half of intrinsic mode function (IMF)
Hilbert transform is made in ripple part, calculates each IMF instantaneous frequency average value, if average value thinks the IMF points higher than 250Hz
Amount belongs to HFS, and the IMF components for representing high frequency are carried out to the high-frequency signal of signal reconstruction acquisition circuit：
Sh(t)=∑ IMFi(t) (7)
The high-frequency signal on two lines road is made into inner product, inner product is -109.26, and less than 0, now energy is maximum in primary election circuit
Outlet be faulty line, therefore circuit L1It is correct for faulty line, route selection.
Example 2
Set bus-bar fault, 30 ° of fault close angle, the Ω of transition resistance 50.
Failure starts line selection algorithm after occurring, and reads before each road outlet failure zero of 3 cycles after half of cycle and failure
Sequence current sampling data.
Row set empirical mode decomposition (EEMD) is entered to each road outlet zero-sequence current sampled data first, by signal decomposition into
Some intrinsic mode function (IMF) components and residual components, to facilitate further extraction fault signature.
In formula：S (t) is primary signal；N is the quantity of IMF components；Ci(t) it is i-th layer of IMF component, wherein C0(t) it is surplus
Remaining component.Component of the intrinsic mode function representation signal of different layers in different time scales.
Afterwards, Hilbert transform is carried out respectively to each layer IMF components and obtains relevant parameter.
In formula：For instantaneous phase；fi(t) it is instantaneous frequency；ai(t) it is instantaneous amplitude.
Instantaneous energy corresponding to the different instantaneous frequencys of each intrinsic mode function (IMF) is further calculated on the basis of formula (10)
Value.Instantaneous energy value is：
Ei(t)=ai(t)2 (11)
Finally ask hilbert spectrum and Hilbert marginal spectrum.
Formula (12) is Hilbert spectrum, and abbreviation hilbert spectrum, it represents instantaneous amplitude in frequency-time plane
Distribution；Formula (13) is Hilbert marginal spectrum, and marginal spectrum is obtained by time-frequency spectrum to time integral.
Selected 0-10Hz low-frequency ranges, as characteristic spectra, are calculated in each road outlet characteristic spectra with more than 250Hz high bands
Marginal spectrum energy it is as shown in table 3.
The circuit limit spectrometry energy of table 3
As can be seen from Table 3, circuit L3And L4Energy is maximum, as primary election circuit.
Faulty line is determined below by high fdrequency component method.To primary election circuit L3And L4First the half of intrinsic mode function (IMF)
Hilbert transform is made in ripple part, calculates each IMF instantaneous frequency average value, if average value thinks the IMF points higher than 250Hz
Amount belongs to HFS, and the IMF components for representing high frequency are carried out to the high-frequency signal of signal reconstruction acquisition circuit：
Sh(t)=∑ IMFi(t) (14)
The high-frequency signal on two lines road is made into inner product, inner product 62.78, more than 0, therefore bus-bar fault, route selection are correct.
Claims (1)
1. a kind of resonant earthed system fault line selection method for single-phase-to-ground fault of high-accuracy, the method includes the steps：
(1) voltage transformer secondary side opening residual voltage is monitored, starts following failure line selection when voltage exceedes threshold value
Step；
(2) fault moment is positioned, reads the zero-sequence current hits of 3 cycles after half of cycle and failure before each bar line fault
According to；
(3) row set empirical mode decomposition (EEMD) is entered to each road outlet zero-sequence current sampled data, by signal decomposition into some
Intrinsic mode function IMF components and residual components, afterwards, Hilbert transform is carried out respectively to each layer IMF components and obtains correlation
Parameter, including instantaneous phase, instantaneous frequency and instantaneous amplitude, instantaneous amplitude square is obtained into instantaneous energy, by time, instantaneous frequency
Rate, instantaneous energy composition hilbert spectrum, obtain Hilbert marginal spectrum to time integral by hilbert spectrum, calculate each road and go out
Line Hilbert marginal spectrum 0-10Hz low-frequency ranges, more than 250Hz high bands instantaneous energy and, select the maximum two lines road of energy
As primary election circuit；
(4) make Hilbert transform to first half-wave part after two primary election circuit intrinsic mode function IMF failure, calculate each
IMF instantaneous frequency average value, select the high frequency division of IMF component reconstruct zero-sequence current of the instantaneous frequency average value higher than 250Hz
Amount, makees inner product by the high fdrequency component on two lines road, if inner product is negative, the maximum primary election circuit of energy is faulty line, if interior
Product exports route selection result, route selection terminates to be then bus-bar fault just.
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| CN110940894A (en) * | 2019-12-16 | 2020-03-31 | 国网北京市电力公司 | Electric shock fault detection method based on instantaneous amplitude-phase sum characteristics of leakage current |
| CN111257687A (en) * | 2020-01-19 | 2020-06-09 | 太原理工大学 | Single-phase earth fault line selection method based on improved MEEMD |
| CN112083353A (en) * | 2020-07-22 | 2020-12-15 | 国网上海市电力公司 | Method and system for detecting open-circuit fault of converter based on switch modal characteristics |
| CN112731061A (en) * | 2020-12-24 | 2021-04-30 | 西安理工大学 | Power distribution network high-resistance fault detection method utilizing comprehensive inner product transformation |
| CN113311290A (en) * | 2021-05-24 | 2021-08-27 | 华北水利水电大学 | Single-phase grounding line selection method suitable for resonant grounding system |
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Cited By (11)
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| CN110007193A (en) * | 2019-03-28 | 2019-07-12 | 国网江苏省电力有限公司无锡供电分公司 | Fault Section Location of Distribution Network based on FDM |
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| CN111257687A (en) * | 2020-01-19 | 2020-06-09 | 太原理工大学 | Single-phase earth fault line selection method based on improved MEEMD |
| CN111257687B (en) * | 2020-01-19 | 2022-03-22 | 太原理工大学 | Single-phase earth fault line selection method based on improved MEEMD |
| CN112083353A (en) * | 2020-07-22 | 2020-12-15 | 国网上海市电力公司 | Method and system for detecting open-circuit fault of converter based on switch modal characteristics |
| CN112731061A (en) * | 2020-12-24 | 2021-04-30 | 西安理工大学 | Power distribution network high-resistance fault detection method utilizing comprehensive inner product transformation |
| CN113311290A (en) * | 2021-05-24 | 2021-08-27 | 华北水利水电大学 | Single-phase grounding line selection method suitable for resonant grounding system |
| CN113655344A (en) * | 2021-09-23 | 2021-11-16 | 广东电网有限责任公司惠州供电局 | Power distribution network fault identification method, device, terminal and medium |
| CN113655344B (en) * | 2021-09-23 | 2023-08-29 | 广东电网有限责任公司惠州供电局 | Power distribution network fault identification method, device, terminal and medium |
| CN115291039A (en) * | 2022-08-09 | 2022-11-04 | 贵州大学 | Single-phase earth fault line selection method of resonance earthing system |
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