CN103293448B - Identification method of single-phase ground fault and virtual grounding based on semi-cycle energy ratio - Google Patents
Identification method of single-phase ground fault and virtual grounding based on semi-cycle energy ratio Download PDFInfo
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- CN103293448B CN103293448B CN201310219227.0A CN201310219227A CN103293448B CN 103293448 B CN103293448 B CN 103293448B CN 201310219227 A CN201310219227 A CN 201310219227A CN 103293448 B CN103293448 B CN 103293448B
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- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 18
- 238000004458 analytical method Methods 0.000 claims abstract description 5
- 229940100688 oral solution Drugs 0.000 claims description 35
- 238000009434 installation Methods 0.000 claims description 3
- 101100257981 Arabidopsis thaliana S-ACP-DES3 gene Proteins 0.000 claims description 2
- 101150057677 DAD3 gene Proteins 0.000 claims description 2
- 102100034004 Gamma-adducin Human genes 0.000 claims description 2
- 101000799011 Homo sapiens Gamma-adducin Proteins 0.000 claims description 2
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- 102100027427 Proline/serine-rich coiled-coil protein 1 Human genes 0.000 claims description 2
- 101100433696 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) AAD3 gene Proteins 0.000 claims description 2
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- 238000005516 engineering process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
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Abstract
The invention relates to an identification method of single-phase ground fault and virtual grounding based on semi-cycle energy ratio, and belongs to the technical field of power system relay protection. The identification method includes after a power distribution network is in failure, extracting zero-sequence voltage data in a cycle after a start component starts, performing wavelet packet decomposition on the front semi-cycle and the rear semi-cycle, figuring out highest frequency energy values according to reconstruction coefficients of the decomposed wavelet packet, comparing the highest frequency energy value of the front semi-cycle and the highest frequency energy value of the rear semi-cycle, and realizing identification of the single-phase ground fault and virtual grounding reliably through comparing with set thresholds. The identification method is simple in principle, obvious in effect and high in reliability; the more accurate wavelet packet analysis method is adopted, bands are divided into multiple levels, and the identification method has high time-frequency resolution and accuracy and better practical value.
Description
Technical field
The present invention relates to a kind of singlephase earth fault based on half cycles energy Ratios and Xuhanting oral solution recognition methods, belong to Relay Protection Technology in Power System field.
Background technology
Along with the development of power distribution network, in urban power distribution network, feeder line gets more and more, cable line proportion is more and more higher, the capacitive earth current of circuit increases day by day, make the distribution network system of neutral by arc extinction coil grounding very possible close to or reach full compensating coefficient, thus causing resonance overvoltage, its magnitude of voltage likely close to neutral excursion voltage when even to exceed singlephase earth fault, produces Xuhanting oral solution phenomenon.When the rising of neutral point voltage causes due to singlephase earth fault, should regulate arc suppression coil that its tuning-off degree is reduced, regulate to full compensation direction; If Xuhanting oral solution phenomenon, then should regulate arc suppression coil that its tuning-off degree is increased, regulate to the direction that over-compensation increases, eliminate series resonance, make neutral point voltage recover normal as early as possible.
By comparing the offset voltage of neutral point, being difficult to find that both singlephase earth fault and Xuhanting oral solution have obvious difference on steady state values, therefore only identifying it is worthless by the size of neutral excursion voltage steady-state value.
Summary of the invention
The technical problem to be solved in the present invention overcomes the recognition methods of tradition to singlephase earth fault and Xuhanting oral solution need to regulate arc suppression coil gear change to monitor the neutral excursion voltage that causes thus or identified by the rate of rise of monitoring residual voltage, and window when needing longer, precision is not high, the weak points such as less reliable.
Technical scheme of the present invention is: a kind of singlephase earth fault based on half cycles energy Ratios and Xuhanting oral solution recognition methods, after power distribution network breaks down, extract the residual voltage data that starting element starts a rear cycle, respectively WAVELET PACKET DECOMPOSITION is carried out to former and later two half cycles, its most high-frequency energy value is tried to achieve respectively by the wavelet package reconstruction coefficient after decomposing, the most high-frequency energy value of front half cycles and the most high-frequency energy value of later half cycle are made ratio, obtains
value, according to itself and setting threshold value
magnitude relationship reliably realize the identification of one-phase earthing failure in electric distribution network and Xuhanting oral solution.
Should be based on the singlephase earth fault of half cycles energy Ratios and Xuhanting oral solution recognition methods concrete steps:
(1), after power distribution network breaks down, its fault residual voltage value can be obtained according to the three-phase voltage that protection installation place records
:
In formula:
,
,
be respectively the voltage of circuit A, B, C three-phase when breaking down;
(2) extract power distribution network to break down the residual voltage data of a rear cycle, utilize analysis method of wavelet packet to decompose former and later two half cycles respectively, and calculate each most high-frequency energy value;
If input signal is
s, after WAVELET PACKET DECOMPOSITION, the frequency band range of gained component of signal is:
Wherein:
jfor the number of plies of wavelet decomposition,
kfor a kth contact of wavelet decomposition,
f sfor the frequency of input signal;
To input signal
scarry out 3 layers of WAVELET PACKET DECOMPOSITION, decompose and there is following relation:
S=AAA3
+DAA3
+ADA3
+DDA3
+AAD3
+DAD3
+ADD3
+DDD3
Wherein:
arepresent low frequency,
drepresent high frequency, the sequence number number at end represents the level of WAVELET PACKET DECOMPOSITION (being also scale parameter);
By the most high-frequency energy value of the wavelet package reconstruction coefficient calculations signal of gained after WAVELET PACKET DECOMPOSITION
e 1, namely
;
(3) the most high-frequency energy that before after setting singlephase earth fault or power distribution network generation Xuhanting oral solution, half cycles obtains after WAVELET PACKET DECOMPOSITION as
e 11, the most high-frequency energy value of later half cycle is
e 12, ask for the two ratio
；
(4) according to ratio
with set threshold value
between relationship distinguish singlephase earth fault and Xuhanting oral solution:
When
time, be then judged to be singlephase earth fault;
When
time, be then judged to be Xuhanting oral solution.
Principle of work of the present invention is:
Along with the development of power distribution network, in urban power distribution network, feeder line gets more and more, cable line proportion is more and more higher, the capacitive earth current of circuit increases day by day, make the distribution network system of neutral by arc extinction coil grounding very possible close to or reach full compensating coefficient, thus generation resonance overvoltage, its magnitude of voltage likely close to neutral excursion voltage when even to exceed singlephase earth fault, produces Xuhanting oral solution phenomenon.Because Xuhanting oral solution is power frequency variation, in theory not containing HF voltage composition, and the neutral excursion voltage that singlephase earth fault causes contains abundant HF voltage composition.Based on this present invention, a kind of singlephase earth fault based on half cycles energy Ratios and Xuhanting oral solution recognition methods are proposed.
The present invention sets about from feeder line residual voltage information when distribution network system singlephase earth fault and Xuhanting oral solution, by carrying out WAVELET PACKET DECOMPOSITION to the signal of two half cycles, its most high-frequency energy value is tried to achieve respectively, by the most high-frequency energy value E of front half cycles by the wavelet package reconstruction coefficient after decomposing
11with the most high-frequency energy value E of later half cycle
12work compares
, obtain
after value, according to itself and set threshold value
between relationship distinguish singlephase earth fault and Xuhanting oral solution:
When
time, be then judged to be singlephase earth fault;
When
time, be then judged to be Xuhanting oral solution.
The invention has the beneficial effects as follows:
(1) this method principle is comparatively simple, and the residual voltage signal that only need gather a cycle identifies fast to singlephase earth fault and Xuhanting oral solution.
(2) this method is from the difference of both the angle research singlephase earth fault of energy and Xuhanting oral solution, and effectiveness comparison is obvious, and reliability is high.
(3) present invention employs meticulousr analysis method of wavelet packet, divided at many levels by frequency band, have higher time frequency resolution and precision, practical value is more extensive.
Accompanying drawing explanation
Fig. 1 is the distribution network system structural drawing for emulating in embodiment: in figure, L
1, L
3, L
5overhead feeder, L
4xian – cable mixing feeder line, L
2, L
6cable feeder line, G is desirable infinitely great capacity power source, and T is main-transformer, T
zbe zigzag transformer, L is arc suppression coil, and R is the damping resistance of arc suppression coil;
Fig. 2 is the fault angle of embodiment 1 feeder line L when being 5 °
1residual voltage oscillogram;
Fig. 3 is the fault angle of embodiment 2 feeder line L when being 90 °
1residual voltage oscillogram;
Feeder line L when Fig. 4 is Xuhanting oral solution in embodiment
1residual voltage oscillogram.
Embodiment
As shown in Figure 1, in figure, supply voltage is 110kV to embodiment 1:110kV/35kV distribution network system realistic model, is down to 35kV through transformer, and its outlet totally 6 feeder lines, Z-shaped transformer neutral point is through arc suppression coil resistance in series ground connection.Feeder line adopts overhead transmission line, overhead line-cable hybrid line and cable line three kinds of circuits.Load selects firm power load model.Overhead feeder L
1=15km, L
3=18km, L
5=30km; Xian – cable mixing feeder line L
4=17km, its overhead feeder 12km, cable 5km; Cable feeder line L
2=6km, L
6=8km.Wherein, overhead feeder is JS1 rod-type, LGJ-70 type wire, span 80m; Cable feeder line is YJV23-35/95 type cable.G in this electrical network is desirable infinitely great capacity power source; T is main-transformer, and no-load voltage ratio is 110 kV/35kV, and connection set is YN/d11; T
zit is zigzag transformer; L is arc suppression coil; R is the damping resistance of arc suppression coil.Feeder line L
1apart from its km place, top 5, singlephase earth fault occurs, stake resistance 20 Ω, fault angle is 5 °, and sample frequency is 10kHz.
Should be based on the singlephase earth fault of half cycles energy Ratios and the step of Xuhanting oral solution recognition methods:
(1), after power distribution network breaks down, its fault residual voltage value can be obtained according to the three-phase voltage that protection installation place records;
(2) feeder line L after extraction one-phase earthing failure in electric distribution network
1the residual voltage data of a cycle, utilize analysis method of wavelet packet to decompose former and later two half cycles respectively, and calculate each most high-frequency energy value;
(3) the most high-frequency energy E that before after trying to achieve fault, half cycles obtains after wavelet package transforms
11and the most high-frequency energy value E of later half cycle
12, and make ratio
;
(4) by gained ratio
with threshold value
relatively, recognition system is singlephase earth fault or Xuhanting oral solution;
Feeder line L is obtained by emulation experiment
1residual voltage waveform as shown in Figure 2, and try to achieve the most high-frequency energy value E of front half cycles
11=2376.1, the most high-frequency energy value E of later half cycle
12=2333.6, threshold value
setting get 0.8 according to the reliability of recognition methods;
=1.018 >
=0.8, therefore judge feeder line
l 1for singlephase earth fault feeder line.
Embodiment 2:110kV/35kV distribution network system realistic model with embodiment 1, feeder line L
1apart from its km place, top 5, singlephase earth fault occurs, stake resistance 20 Ω, fault angle is 90 °, and sample frequency is 10kHz.
Should based on the singlephase earth fault of half cycles energy Ratios and the step of Xuhanting oral solution recognition methods with example 1.
Feeder line L is obtained by emulation experiment
1residual voltage waveform as shown in Figure 3, and try to achieve the most high-frequency energy value ratio of former and later two half cycles
=169.6 >
=0.8, so feeder line L can be judged
1for singlephase earth fault feeder line.
Embodiment 3:110kV/35kV distribution network system realistic model, with embodiment 1, after magnitude of voltage is out-of-limit, obtains cycle residual voltage data.
Should based on the singlephase earth fault of half cycles energy Ratios and the step of Xuhanting oral solution recognition methods with embodiment 1.
Feeder line L is obtained by emulation experiment
1residual voltage waveform as shown in Figure 4, and try to achieve the most high-frequency energy value ratio of former and later two half cycles
=0.439 <
=0.8, so can judge that system there occurs Xuhanting oral solution phenomenon.
In like manner, can according to same steps in above-mentioned example, under research different faults initial angle and Xuhanting oral solution time most high-frequency energy ratio, the results detailed in Table 1.This ratio much larger than 1, and close to 1 during Xuhanting oral solution, as known from Table 1, should lose efficacy when fault initial angle is near 0 ° based on the singlephase earth fault recognition methods of half cycles energy Ratios, there is certain dead band in singlephase earth fault situation.
By reference to the accompanying drawings the specific embodiment of the present invention is explained in detail above, but the present invention is not limited to above-mentioned embodiment, in the ken that those of ordinary skill in the art possess, can also make a variety of changes under the prerequisite not departing from present inventive concept.
Claims (2)
1. the singlephase earth fault based on half cycles energy Ratios and Xuhanting oral solution recognition methods, it is characterized in that: after power distribution network breaks down, extract the residual voltage data that starting element starts a rear cycle, 3 layers of WAVELET PACKET DECOMPOSITION are carried out respectively to former and later two half cycles, its most high-frequency energy value is tried to achieve respectively by the wavelet package reconstruction coefficient after decomposing, the most high-frequency energy value of front half cycles and the most high-frequency energy value of later half cycle are made ratio, obtains
value, according to itself and setting threshold value
magnitude relationship reliably realize the identification of one-phase earthing failure in electric distribution network and Xuhanting oral solution.
2. the singlephase earth fault based on half cycles energy Ratios according to claim 1 and Xuhanting oral solution recognition methods, is characterized in that: the concrete steps of described one-phase earthing failure in electric distribution network and Xuhanting oral solution recognition methods are as follows:
(1), after power distribution network breaks down, its fault residual voltage value can be obtained according to the three-phase voltage that protection installation place records
:
In formula:
,
,
be respectively the voltage of circuit A, B, C three-phase when breaking down;
(2) extract power distribution network to break down the residual voltage data of a rear cycle, utilize analysis method of wavelet packet to decompose former and later two half cycles respectively, and calculate each most high-frequency energy value;
If input signal is
s, after WAVELET PACKET DECOMPOSITION, the frequency band range of gained component of signal is:
Wherein:
jfor the number of plies of wavelet decomposition,
kfor a kth contact of wavelet decomposition,
f sfor the frequency of input signal;
To input signal
scarry out 3 layers of WAVELET PACKET DECOMPOSITION, decompose and there is following relation:
S=AAA3
+DAA3
+ADA3
+DDA3
+AAD3
+DAD3
+ADD3
+DDD3
Wherein:
arepresent low frequency,
drepresent high frequency, the sequence number number at end represents the level of WAVELET PACKET DECOMPOSITION (being also scale parameter);
By the most high-frequency energy value of the wavelet package reconstruction coefficient calculations signal of gained after WAVELET PACKET DECOMPOSITION
e 1, namely
;
(3) the most high-frequency energy that before after setting singlephase earth fault or power distribution network generation Xuhanting oral solution, half cycles obtains after WAVELET PACKET DECOMPOSITION as
e 11, the most high-frequency energy value of later half cycle is
e 12, ask for the two ratio
；
(4) according to ratio
with set threshold value
between relationship distinguish singlephase earth fault and Xuhanting oral solution:
When
time, be then judged to be singlephase earth fault;
When
time, be then judged to be Xuhanting oral solution.
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| CN104133144B (en) * | 2014-08-04 | 2017-04-12 | 昆明理工大学 | Magnetizing inrush current discrimination method based on differential current wavelet packet decomposition |
| CN104777404B (en) * | 2015-04-28 | 2018-01-12 | 上海交通大学 | Based on differential energy than distribution line fault section location method |
| CN104991165A (en) * | 2015-06-30 | 2015-10-21 | 昆明理工大学 | Fault judgment method based on zero sequence voltage transient state quantity SVD (Singular Value Decomposition) |
| CN106597202A (en) * | 2016-12-27 | 2017-04-26 | 国网浙江省电力公司 | Single-phase grounding fault detection method and device applied to line switch |
| CN111487508A (en) * | 2020-06-01 | 2020-08-04 | 南方电网调峰调频发电有限公司西部检修试验分公司 | Single-phase high-resistance grounding fault identification device for power distribution network |
| CN111965480A (en) * | 2020-07-06 | 2020-11-20 | 国网江苏省电力有限公司淮安供电分公司 | Complex power distribution network fault line selection method based on wavelet transformation |
| CN115356599B (en) * | 2022-10-21 | 2023-04-07 | 国网天津市电力公司城西供电分公司 | Multi-mode urban power grid fault diagnosis method and system |
| CN116990632A (en) * | 2023-06-21 | 2023-11-03 | 国网山东省电力公司济宁市任城区供电公司 | Single-phase high-resistance ground fault detection method and system for power distribution network |
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| CN100530883C (en) * | 2007-10-11 | 2009-08-19 | 天津大学 | Route selection method for single-phase ground fault of two-phase TA power distribution network |
| CN102768324B (en) * | 2012-04-10 | 2014-12-31 | 河南理工大学 | Single-phase ground fault section positioning method for low-current grounding system |
| CN103018627B (en) * | 2012-10-25 | 2014-12-31 | 福建省电力有限公司 | Adaptive fault type fault line detection method for non-effectively earthed system |
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