CN102590703B - Single-phase grounding failure route selection method of resonance grounding system based on zero-sequence transient charge - Google Patents

Single-phase grounding failure route selection method of resonance grounding system based on zero-sequence transient charge Download PDF

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CN102590703B
CN102590703B CN201210036898.9A CN201210036898A CN102590703B CN 102590703 B CN102590703 B CN 102590703B CN 201210036898 A CN201210036898 A CN 201210036898A CN 102590703 B CN102590703 B CN 102590703B
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zero
feeder line
zero sequence
transient
sequence transient
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CN201210036898.9A
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CN102590703A (en
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何正友
林圣�
张姝
王玘
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西南交通大学
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Abstract

The invention discloses a single-phase grounding failure route selection method of a resonance grounding system based on zero-sequence transient charge, comprising the main steps: collecting a three-phase current signal and a three-phase voltage signal of a distribution network feeder bus as input quantity of a route selection element; performing decoupling calculation to obtain zero-sequence current and zero-sequence voltage of the feed lines, and filtering the power frequency component in the corresponding electric quantity; figuring out zero-sequence transient charge quantity accumulated during a failure transient process according to the zero-sequence transient current of the feed lines; and comparing the relative coefficient values of the obtained zero-sequence transient voltage with the zero-sequence transient electric charge quantity of the feed lines to judge whether the feed line with minimal relative coefficient is the failure feed line, so as to finish the identification of the failure feed line. The method disclosed by the invention can reliably identify the failure feed line under various failure conditions, an emulation result indicates that the method has high sensitivity and reliability under various operation working conditions, and the method has good anti-interference capability and has no special demand on equipment, so that the method can be used for realizing fast failure diagnosis of the resonance grounding system.

Description

Based on the resonant earthed system fault line selection method for single-phase-to-ground fault of zero sequence transient charge

Technical field

The present invention relates to a kind of resonant earthed system fault line selection method for single-phase-to-ground fault based on zero sequence transient charge in electric system.

Background technology

At present, adopt the resonant earthed system of arc suppression coil due to after circuit generation singlephase earth fault, fault current is subject to the compensation of arc suppression coil and diminishes, so can self-extinguish ground arc; Simultaneously resonant earthed system is due to still retention wire voltage three-phase symmetrical after singlephase earth fault, does not affect the power supply capacity to load, therefore allows charging operation 1-2 hour.But along with the development of power distribution network, bus feeder line increases and the use of cable in circuit year by year, short circuit capacitance electric current is increased, long-play easily produces multipoint earth faults, so fault feeder must be judged rapidly and accurately within limited working time, for the accurate location of further fault and failture evacuation provide foundation.

For the failure line selection of power distribution network resonant earthed system, although power frequency amount energy is large but be subject to the compensation of arc suppression coil, fundametal compoment amplitude and direction all can produce larger change, based on this reason, the transient produced after analysis of failure, realizes being that the selection method of criterion progressively becomes research and practical focus with transient information.But high resistance earthing fault is the difficult point of route selection in power distribution network always, because stake resistance is excessive, after fault, the amplitude of transient is very little, causes extreme difficulties to route selection accurate after resonant earthed system fault.

Summary of the invention

The object of the invention is the weak point overcoming existing power distribution network resonant earthed system failure line selection, a kind of resonant earthed system fault line selection method for single-phase-to-ground fault based on zero sequence transient charge is proposed, the route selection of this selection method is highly sensitive, speed fast, accurately can locate provide foundation more accurately and reliably with failture evacuation for further fault.

The present invention is for solving its technical matters, and the technical scheme adopted is a kind of resonant earthed system fault line selection method for single-phase-to-ground fault based on zero sequence transient charge, the steps include:

A, the three-phase current signal gathering power distribution network each bar feeder line bus end and three-phase voltage signal, after choosing singlephase earth fault, first semiperiod of each bar feeder line or the sampled data of holocyclic three-phase current signal and three-phase voltage signal are as the input quantity of route selection element;

B, decoupling zero is carried out to the input quantity of the route selection element chosen, obtain zero-sequence current component and the zero sequence voltage component of each bar feeder line respectively;

50Hz power frequency component in C, filtering each bar feeder line zero-sequence current and residual voltage, obtain corresponding zero sequence transient current and zero sequence transient voltage, and obtain in first selected semiperiod or time in complete period the zero sequence transient charge amount be accumulated on feeder line according to the zero sequence transient current of each bar feeder line;

D, set up the corresponding relation of each bar feeder line zero sequence transient charge amount and zero sequence transient voltage, calculate the transient zero-sequence voltage of each bar feeder line and the related coefficient of zero sequence transient charge amount, the minimum feeder line of related coefficient is judged to be fault feeder.

Compared with prior art, the invention has the beneficial effects as follows:

One, the relativeness that the transient charge amount that the present invention passes through to accumulate in half or one-period changes at distribution and each feeder line transient voltage of each feeder line, because the transient information amount utilized is accumulation, improve the recognition capability to feeble signal, overcome the shortcoming that high resistance earthing fault causes transient current information too small, solve the transient state electric parameters problem that extremely faint caused route selection is inaccurate in high resistance ground situation, improve sensitivity and the accuracy of the route selection of resonant earthed system high resistance ground.

Two, there is singlephase earth fault in resonant earthed system and can produce two transient state processes simultaneously.One is that faulted phase voltage reduces suddenly and the discharge capacity electric current caused, and another is that non-faulted phase voltage raises suddenly the charging capacitor electric current caused.Discharge capacity electric current flows to trouble spot by bus, directly forms flow cycle through fault phase line mutual-ground capacitor and ground, and then charging capacitor electric current then forms path through healthy phases line mutual-ground capacitor and ground by transformer.The present invention is by the total charge dosage asking for two transient state charge and discharge process and accumulate in first semiperiod or the complete period distribution relation with corresponding transient voltage, investigate the correlation coefficient value of different both feeder lines, this correlation coefficient value more close to 1, reflect this feeder line load stabilization, disturb little; This correlation coefficient value contrary is more less than 1, illustrates that its load there occurs sudden change or receives interference; Therefore, the feeder line that after breaking down, correlation coefficient value is minimum can be judged to be faulty line.It is without the direction of Direct Recognition transient current and size, and route selection criterion is simple, facilitates execute-in-place.

Three, the discharge and recharge transient state process that when the transient charge amount owing to accumulating is resonant earthed system generation singlephase earth fault, self produces is formed, and not by the impact of system neutral degree of compensation, also makes its route selection accurately, reliably; And only need the three-phase electricity flow and the voltage that gather each bar feeder line of bus bar side, and not high to equipment requirement, equally, improve the reliability of method.

Four, when the present invention only needs to gather single-phase earthing, the transient of capacitor charge and discharge process, is generally between hundreds of to a few KHz, so sample frequency scope is at 10kHz ~ 20kHz, to sample devices without particular/special requirement, and convenient enforcement.

In above-mentioned C step, the specific practice obtaining the zero sequence transient charge amount be accumulated on feeder line in first selected semiperiod or time in complete period according to the zero sequence transient current of each bar feeder line is;

By following discrete integration formula draw occur single-phase fault begin i-th sampling interval time in the quantity of electric charge accumulated

Q 0 i ′ n = Q 0 i - 1 ′ n + 1 2 × ( I 0 i - 1 ′ n - I 0 i ′ n ) × Δt

In formula, be the zero sequence transient current that i-th sampling interval of n-th feeder line gathers, Δ t is the time of sampling interval; When or during i=T/ Δ t, T is the cycle of three-phase electricity, the quantity of electric charge calculated be in first semiperiod or time in complete period the zero sequence transient charge amount be accumulated on n-th feeder line

Adopt the zero sequence transient charge amount that can calculate each bar feeder line in this way easily and fast and accumulate within access time.

Below in conjunction with embodiment, the present invention is described in further detail.

Accompanying drawing explanation

The realistic model topological structure of the emulation experiment of Fig. 1 embodiment of the present invention.

The zero sequence transient charge amount of feeder line 1-4 and the relation of zero sequence transient voltage in the emulation experiment of Fig. 2 embodiment of the present invention.

Embodiment

Embodiment

A kind of embodiment of the present invention is, a kind of resonant earthed system fault line selection method for single-phase-to-ground fault based on zero sequence transient charge, the steps include:

A, the three-phase current signal gathering power distribution network each bar feeder line bus end and three-phase voltage signal, after choosing single-phase fault, first semiperiod (i.e. 10ms) of each bar feeder line or the three-phase current signal in complete period (20ms) and the sampled data of three-phase voltage signal are as the input quantity of route selection element.

B, decoupling zero is carried out to the input quantity of the route selection element chosen, obtain zero-sequence current component and the zero sequence voltage component of each bar feeder line respectively.

During decoupling zero, various existing decoupling zero can be adopted to carry out, as symmetrical component transformation can be adopted to carry out, specific as follows:

I 1 I 2 I 0 = 1 3 1 α α 2 1 α 2 α 1 1 1 I A I B I C - - - ( 1 )

U 1 U 2 U 0 = 1 3 1 α α 2 1 α 2 α 1 1 1 U A U B U C - - - ( 2 )

In formula (1), I a, I b, I cbe respectively A, B, C phase current that each bar feeder line obtains in the measurement of bus place; I 0for zero-sequence current; I 1for forward-order current; I 2for negative-sequence current.

In formula (2), U a, U b, U cbe respectively A, B, C phase voltage that each bar feeder line obtains in the measurement of bus place; U 0for residual voltage; U 1for positive sequence voltage; U 2for negative sequence voltage.

In formula (1) and (2), α is twiddle factor, and its expression formula is:

α = e j 120 0 = - 1 2 + j 3 2 - - - ( 3 )

α 2 = e j 240 0 = - 1 2 - j 3 2 - - - ( 4 )

By above symmetrical component transformation, the asymmetric current-voltage information after generation singlephase earth fault is transformed into three symmetrical order components, the feeder line zero-sequence current component I wherein obtained 0, zero sequence voltage component U 0be the information that next-step operation needs.

50Hz power frequency component in C, filtering each bar feeder line zero-sequence current and residual voltage, obtain corresponding zero sequence transient current and zero sequence transient voltage, and obtain in first selected semiperiod or time in complete period the zero sequence transient charge amount be accumulated on feeder line according to the zero sequence transient current of each bar feeder line.

In this example, the specific practice obtaining the zero sequence transient charge amount be accumulated on feeder line in first selected semiperiod or time in complete period according to the zero sequence transient current of each bar feeder line is;

By following discrete integration formula draw occur single-phase fault begin i-th sampling interval time in the quantity of electric charge accumulated

Q 0 i ′ n = Q 0 i - 1 ′ n + 1 2 × ( I 0 i - 1 ′ n + I 0 i ′ n ) × Δt

In formula, be the zero sequence transient current that i-th sampling interval of n-th feeder line gathers, Δ t is the time of sampling interval; When or during i=T/ Δ t, T is the cycle (20ms) of three-phase electricity, the quantity of electric charge calculated be in first semiperiod or time in complete period the zero sequence transient charge amount be accumulated on n-th feeder line

D, set up the corresponding relation of each bar feeder line zero sequence transient charge amount and zero sequence transient voltage, calculate the transient zero-sequence voltage of each bar feeder line and the related coefficient of zero sequence transient charge amount, the minimum feeder line of related coefficient is judged to be fault feeder.

The computing formula of the transient zero-sequence voltage of each bar feeder line and the related coefficient of zero sequence transient charge amount is:

ρ n = Cov ( U 0 ′ n , Q 0 ′ n ) D ( U 0 ′ n ) · D ( Q 0 ′ n )

In formula, ρ nrepresent the zero sequence transient voltage amount of n-th feeder line and the related coefficient of zero sequence transient charge amount, represent the zero sequence transient voltage amount of n-th feeder line and the covariance of zero sequence transient charge amount, represent the variance of the zero sequence transient voltage amount of n-th feeder line, represent the variance of the zero sequence transient charge amount of n-th feeder line.

Emulation experiment:

For checking the inventive method has carried out emulation experiment to above method, the simulation experiment result shows that its route selection is highly sensitive, and route selection speed is fast, and route selection accurately and reliably.

In conjunction with an actual motion line parameter circuit value, to build electric pressure be the single supply 4 feeder line resonant earthed system of 35kV is empirical model, and circuit is the overhead transmission line model of frequency dependence.Its topology as shown in Figure 1.Correlation parameter is: the length of feeder line 1 is 30km, and the length of feeder line 2 is 19km, and the length of feeder line 3 is 10km, and feeder line 4 length is 6km.The positive and negative sequence impedance Z of overhead transmission line 1=Z 2=0.25542+j0.37294 Ω/km, positive and negative sequence admittance Y 1=Y 2=j3.0803 × 10 -6s/km, zero sequence impedance Z 0=0.51664+j1.48516 Ω/km, zero sequence admittance Y 0=j1.47574326 × 10 -6s/km, Arc Suppression Coil Compensation Degree is set to over-compensation 10%, and signal pickup assembly is installed in the data acquisition that each bar feeder line bus end carries out three-phase fault electric current and three-phase fault voltage.

Data sampling rate is 20kHz, and data window length gets 414 points and one-period, supposes that feeder line 1 A phase earth fault occurs, transition resistance R=2000 Ω at t=0.3243s distance bus l=18km place.Then can calculate: the zero sequence transient charge amount that feeder line 1-4 accumulates in one-period, the correlation coefficient value ρ of corresponding zero sequence transient charge amount and zero sequence transient voltage 1=-0.1084, ρ 2=0.9992, ρ 3=0.9986, ρ 4=0.9951.According to criterion, ρ 1minimum, therefore feeder line 1 is fault feeder.Fig. 2 is, the zero sequence transient charge amount of feeder line 1-4 at each hours cumulative of one-period and the relation curve of zero sequence transient voltage, the curve of lineal layout of leveling off in Fig. 2 is feeder line 2, the relation curve of 3,4, and the curve of random distribution is fault feeder curve, also feeder line 2 is described, 3, on 4, zero sequence transient charge amount and zero sequence transient voltage are the positively related relation of highly linear, and on feeder line 1, zero sequence transient charge amount and zero sequence transient voltage do not have obvious correlationship.

The route selection result of the inventive method under the operating mode of different faults Distance geometry different faults stake resistance is given with following table 1 and table 2.

Table 1 for feeder line 1 different distance place occur A phase earth fault time (time of failure is 0.3243s, transition resistance R=2800 Ω) route selection results contrast:

Table 1

√: represent protection route selection result and actual to arrange fault feeder result consistent

Table 2 is the comparison of feeder line 1 (time of failure for 0.3243s, fault distance l=15km) route selection result when there is A phase earth fault with different grounding resistance.

Table 2

√: represent protection route selection result and actual to arrange fault feeder result consistent

The route selection result of table 1 and table 2 shows, under the working condition of various fault distance and fault ground resistance, the zero sequence transient charge amount of fault feeder and the degree of correlation of zero sequence transient voltage are all starkly lower than healthy feeder line.Its route selection result accurately and be easy to operating personnel and read, confirms that this inventive method has very high dependable with function.

More than test and do not consider noise effect, for the adaptability of checking the present invention in practical engineering application, to the three-phase current collected and voltage signal superposition white Gaussian noise, simulate the signal disturbing that may occur in actual applications, to verify the route selection fiduciary level of the present invention under low signal-to-noise ratio.

Singlephase earth fault is there is in feeder line 1 apart from bus 20km place, data sampling rate is 20kHz, (t=0.3243s) 414 sampled points (one-period) after data window length gets fault, table 3 is the route selection results contrast of the inventive method in unlike signal signal to noise ratio (S/N ratio) (Signal-to-noise ratio, SNR) situation.

Table 3

√: represent protection route selection result and actual to arrange fault feeder result consistent

Add Gauss's noise experiment result to show: input signal signal to noise ratio (S/N ratio) all correctly can complete failure line selection from 10dB to 70dB.But can find that signal to noise ratio (S/N ratio) is when more than 40dB, the zero sequence transient charge amount of healthy feeder line and the related coefficient of zero sequence transient voltage, all more than 0.95, illustrate that the zero sequence transient charge amount distribution of healthy feeder line and zero sequence transient voltage change linear degree high.Along with the reduction of signal to noise ratio (S/N ratio), noise affects greatly electric parameters effective information, and the correlation coefficient value that the charge amount distribution of fault feeder and healthy feeder line is corresponding with it also produces larger change.But fault feeder correlation coefficient value is starkly lower than healthy feeder line all the time.The analysis of comprehensive above fault condition, illustrates that route selection of the present invention is highly sensitive, and antijamming capability is strong, can adapt to on-the-spot practical application.

Claims (2)

1., based on a resonant earthed system fault line selection method for single-phase-to-ground fault for zero sequence transient charge, the steps include:
A, the three-phase current signal gathering power distribution network each bar feeder line bus end and three-phase voltage signal, after choosing singlephase earth fault, first semiperiod of each bar feeder line or the sampled data of holocyclic three-phase current signal and three-phase voltage signal are as the input quantity of route selection element;
B, decoupling zero is carried out to the input quantity of the route selection element chosen, obtain zero-sequence current component and the zero sequence voltage component of each bar feeder line respectively;
50Hz power frequency component in C, filtering each bar feeder line zero-sequence current and residual voltage, obtain corresponding zero sequence transient current and zero sequence transient voltage, and obtain in first selected semiperiod or time in complete period the zero sequence transient charge amount be accumulated on each bar feeder line according to the zero sequence transient current of each bar feeder line;
D, set up the corresponding relation of each bar feeder line zero sequence transient charge amount and zero sequence transient voltage, calculate the zero sequence transient voltage of each bar feeder line and the related coefficient of zero sequence transient charge amount, the minimum feeder line of related coefficient is judged to be fault feeder.
2. the resonant earthed system fault line selection method for single-phase-to-ground fault based on zero sequence transient charge according to claim 1, it is characterized in that: in described C step, the specific practice obtaining the zero sequence transient charge amount be accumulated on each bar feeder line in first selected semiperiod or time in complete period according to the zero sequence transient current of each bar feeder line is:
By following discrete integration formula draw occur singlephase earth fault begin i-th sampling interval time in the quantity of electric charge accumulated
Q 0 i ′ n = Q 0 i - 1 ′ n + 1 2 × ( I 0 i - 1 ′ n + I 0 i ′ n ) × Δt
In formula, be the zero sequence transient current that i-th sampling interval of n-th feeder line gathers, △ t is the time of sampling interval; When or during i=T/ △ t, T is the cycle of three-phase electricity, the quantity of electric charge calculated be in first semiperiod or time in complete period the zero sequence transient charge amount be accumulated on n-th feeder line
CN201210036898.9A 2012-02-18 2012-02-18 Single-phase grounding failure route selection method of resonance grounding system based on zero-sequence transient charge CN102590703B (en)

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CN102944806B (en) * 2012-11-20 2014-11-05 中国石油大学(华东) Zero sequence current polarity comparison-based resonant earthed system line selection method
CN103207352B (en) * 2013-03-13 2015-09-02 福建省电力有限公司 Route selection impedance magnitude characteristic is utilized to realize wire selection method for power distribution network single phase earthing failure
WO2014154164A1 (en) * 2013-03-29 2014-10-02 北京映翰通网络技术股份有限公司 Method and system for detecting and locating single-phase ground fault on low current grounded power-distribution network
CN103323747B (en) * 2013-06-27 2016-08-10 国家电网公司 A kind of fault line selection method for single-phase-to-ground fault of small current neutral grounding system
CN103675605B (en) * 2013-12-11 2016-03-09 湖南大学 A kind of power distribution network earth fault line selection method based on the correlation analysis of fault-signal transient state
CN104617566B (en) * 2015-01-23 2017-09-12 昆明理工大学 A kind of small current neutral grounding system single-phase fault based on the positive and negative area sum of residual voltage starts method
CN105044550A (en) * 2015-04-28 2015-11-11 国家电网公司 Distribution network line fault positioning method based on fault current discharge path
CN106896294A (en) * 2017-03-27 2017-06-27 国家电网公司 Non-effectively earthed system fault-line selecting method based on transient state discharge capacity
CN108132417A (en) * 2017-11-24 2018-06-08 国网北京市电力公司 Method for locating single-phase ground fault and device

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