CN103675537B - A kind of based on the power distribution network Xuhanting oral solution recognition methods of consecutive points distance in the plane of adjacent difference composition of residual voltage - Google Patents

Abstract

The present invention relates to a kind of based on the power distribution network Xuhanting oral solution recognition methods of consecutive points distance in the plane of adjacent difference composition of residual voltage, belong to Relay Protection Technology in Power System field.The present invention is when the power distribution network of neutral by arc extinction coil grounding breaks down or during Xuhanting oral solution, extracts the distribution bus residual voltage data in short time-window after fault or Xuhanting oral solution；Ask for first-order difference and the second differnce of residual voltage data, with first-order difference and second differnce formation level, ask for the quadratic sum of consecutive points distance in this plane, according to the size of consecutive points square distance sum, Xuhanting oral solution and singlephase earth fault are judged.The present invention only need residual voltage data are carried out difference, square and read group total, calculate simple, it is easy to realize.

Description

A kind of based on the power distribution network Xuhanting oral solution recognition methods of consecutive points distance in the plane of adjacent difference composition of residual voltage

Technical field

The present invention relates to a kind of based on the power distribution network Xuhanting oral solution recognition methods of consecutive points distance in the plane of adjacent difference composition of residual voltage, belong to Relay Protection Technology in Power System field.

Background technology

When the power distribution network of neutral by arc extinction coil grounding is properly functioning, arc suppression coil is generally in overcompensation state.When system feeder line increases, system capacity current increases, automatic tuning apparatus can regulate arc suppression coil inductance value from the change of motion tracking capacitance current, in adjustment process, system probably enters full compensating coefficient, thus producing parallel resonance overvoltage, resonance overvoltage may close to neutral point displacement voltage during even more than singlephase earth fault, and this phenomenon is called Xuhanting oral solution.If the rising of neutral point voltage causes because of singlephase earth fault, arc suppression coil should be regulated and make tuning-off degree reduce, regulate to full compensation direction；If the rising of neutral point voltage causes because of Xuhanting oral solution, then should regulate arc suppression coil and make its tuning-off degree increase, regulate to the direction that overcompensation increases, to eliminate parallel resonance.

The neutral point displacement voltage that single-phase earthing and Xuhanting oral solution cause is distinguished inconspicuous on steady state values, therefore is difficult to Xuhanting oral solution and single-phase earthing be carried out identification by comparing the size of neutral point displacement voltage steady-state value.Practical operating experiences shows, has two kinds of methods at present to identifying that Xuhanting oral solution and single-phase earthing are highly effective.One is after neutral point voltage raises, and regulates arc suppression coil gear, changes equivalent inductance value, distinguishes the two by monitoring the neutral point voltage change thus caused.Another kind of method is by the rate of rise of monitoring residual voltage, the two to be distinguish between.But the taken window of above two method is all longer, is unfavorable for finding in time singlephase earth fault.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of based on the Xuhanting oral solution of consecutive points distance in the plane of adjacent difference composition of residual voltage and the method for discrimination of singlephase earth fault, overcomes existing identification Xuhanting oral solution and the taken window of single-phase earthing method is longer, be unfavorable for finding in time the deficiency of singlephase earth fault.

The technical scheme is that a kind of based on the power distribution network Xuhanting oral solution recognition methods of consecutive points distance in the plane of adjacent difference composition of residual voltage, when the power distribution network of neutral by arc extinction coil grounding breaks down, distribution bus residual voltage data in short time-window after extraction fault or Xuhanting oral solution, ask for first-order difference and the second differnce of residual voltage data, with first-order difference and second differnce formation level, ask for the quadratic sum of consecutive points distance in this plane, according to the size of consecutive points square distance sum, Xuhanting oral solution and singlephase earth fault are differentiated.

Described method specifically comprises the following steps that

(1) after distribution network line generation singlephase earth fault or Xuhanting oral solution, line selection apparatus starts and records ripple immediately, records bus residual voltage；

(2) extraction is broken down or the residual voltage data u in short time-window after Xuhanting oral solution₀N (), calculates first-order difference d [1] (n) and second differnce d [2] (n):

D [1] (n)=u₀(n)-u₀(n-1)

D [2] (n)=d [1] (n)-d [1] (n-1)

In formula, n is discrete data the n-th sampled point；

(3) with d [2] (n) for transverse axis, construct adjacent order differential planar with d [1] (n) for the longitudinal axis, ask for square dist2 (n) of consecutive points distance in this plane²；

dist2(n)²=[d [2] (n)-d [2] (n-1)]²+[d[1](n)-d[1](n-1)]²

(4) to data dist2 (n)²Summation, tries to achieve dist2_sum:

$dist{2}_{sum}=\underset{n=1}{\overset{N}{\Σ}}dist2{\left(n\right)}^2$

In formula: N is total number of sample points；

(5) dist2 is judged_sumSize:

If dist2_sumIf greater than 1, then it is earth fault；

If dist2_sumLess than or equal to 1, then it it is Xuhanting oral solution.

Principles of the invention is:

1, first-order difference and second differnce are asked for:

Extract and break down or the residual voltage data u of 5ms after Xuhanting oral solution₀N (), calculates first-order difference d [1] (n) and second differnce d [2] (n):

D [1] (n)=u₀(n)-u₀(n-1)(1)

D [2] (n)=d [1] (n)-d [1] (n-1) (2)

In formula, n is discrete data the n-th sampled point；

2, consecutive points square distance and calculating on adjacent order differential planar:

Define with d [2] (n) for transverse axis, with d [1] (n) in the plane of the longitudinal axis consecutive points distance square be:

dist2(n)²=[d [2] (n)-d [2] (n-1)]²+[d[1](n)-d[1](n-1)]²(3)

To breaking down or the dist2 (n) of 5ms after Xuhanting oral solution²Sue for peace, ask for dist2_sum

$dist{2}_{sum}=\underset{n=1}{\overset{N}{\Σ}}dist2{\left(n\right)}^2---\left(4\right)$

3, the differentiation of Xuhanting oral solution and singlephase earth fault:

When there is Xuhanting oral solution, residual voltage amplitude is gradually increased, and on the mapped plan that first-order difference and second differnce construct, the distance between consecutive points is less.When there is singlephase earth fault, residual voltage instantaneous value is increased to tens or tens kV suddenly by zero, and compared with Xuhanting oral solution situation, on the mapped plan that first-order difference and second differnce are formed, the distance between consecutive points is bigger.Following criterion can be adopted to carry out singlephase earth fault and Xuhanting oral solution differentiates: if dist2_sum> 1, then it is judged as earth fault；If dist2_sum≤ 1, then it is judged as Xuhanting oral solution.

The invention has the beneficial effects as follows:

1, only need residual voltage data are carried out difference, square and read group total, calculate simple, it is easy to realize；

2, adopting 5ms short time-window to carry out decision analysis, taken window is shorter；

Accompanying drawing explanation

Fig. 1 is embodiment of the present invention resonator system singlephase earth fault phantom；

The oscillogram of residual voltage when Fig. 2 is singlephase earth fault of the present invention；

The oscillogram of residual voltage when Fig. 3 is Xuhanting oral solution of the present invention；

When Fig. 4 is generation Xuhanting oral solution of the present invention, corresponding dist2 (n)²Waveform；

When Fig. 5 is generation singlephase earth fault of the present invention, corresponding dist2 (n)²Waveform；

Fig. 6 is flow chart of steps of the present invention.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, the invention will be further described.

Embodiment 1: a kind of based on the power distribution network Xuhanting oral solution recognition methods of consecutive points distance in the plane of adjacent difference composition of residual voltage, when the power distribution network of neutral by arc extinction coil grounding breaks down, distribution bus residual voltage data in short time-window after extraction fault or Xuhanting oral solution, ask for first-order difference and the second differnce of residual voltage data, with first-order difference and second differnce formation level, ask for the quadratic sum of consecutive points distance in this plane, according to the size of consecutive points square distance sum, Xuhanting oral solution and singlephase earth fault are differentiated.

Described method specifically comprises the following steps that

(1) after distribution network line generation singlephase earth fault or Xuhanting oral solution, line selection apparatus starts and records ripple immediately, records bus residual voltage；

(2) extraction is broken down or the residual voltage data u of 5ms after Xuhanting oral solution₀N (), calculates first-order difference d [1] (n) and second differnce d [2] (n):

D [1] (n)=u₀(n)-u₀(n-1)

D [2] (n)=d [1] (n)-d [1] (n-1)

In formula, n is discrete data the n-th sampled point；

(3) with d [2] (n) for transverse axis, construct adjacent order differential planar with d [1] (n) for the longitudinal axis, ask for square dist2 (n) of consecutive points distance in this plane²；

dist2(n)²=[d [2] (n)-d [2] (n-1)]²+[d[1](n)-d[1](n-1)]²

(4) to data dist2 (n)²Summation, tries to achieve dist2_sum:

$dist{2}_{sum}=\underset{n=1}{\overset{N}{\Σ}}dist2{\left(n\right)}^2$

In formula: N is total number of sample points；

(5) dist2 is judged_sumSize:

If dist2_sumIf greater than 1, then it is earth fault；

If dist2_sumLess than or equal to 1, then it it is Xuhanting oral solution.

Embodiment 2: 110kV/35kV neutral by arc extinction coil grounding distribution network system singlephase earth fault phantom as shown in Figure 1, it has 6 feeder lines, and Z-shaped transformer neutral point is by arc suppression coil series resistance ground.Overhead feeder L₁=15km, L₃=18km, L₅=30km, cable mixing feeder line L₄=17km, its overhead feeder 12km, cable 5km, cable feeder line L₂=6km, L₆=8km.Wherein, overhead feeder is JS1 rod-type, LGJ-70 type wire, span 80m, and cable feeder line is YJV23-35/95 type cable.G in this electrical network is infinitely great power supply；T is main transformer, and no-load voltage ratio is 110kV/35kV, and connection set is Y_N/d11；T_ZIt it is zigzag transformator；L is arc suppression coil；R is the damping resistance of arc suppression coil.Feeder line adopts overhead transmission line, aerial line cable hybrid line and three kinds of circuits of cable run.

It is now assumed that feeder line L₁There is A phase earth fault in distance bus 5km place, the initial phase angle of fault is 0 °, and sample rate is set to 10kHz.Under the model, emulation obtains during singlephase earth fault zero sequence voltage on neutral point value as shown in Figure 4.The residual voltage data of window during 5ms after selecting device startup, ask for first-order difference and the second differnce of residual voltage data, with d [2] (n) for transverse axis, with d [1] (n) for longitudinal axis formation level, ask for the quadratic sum of consecutive points distance in this plane, calculate and obtain dist2_sum=7.83, because dist2_sum> 1, it is determined that be singlephase earth fault, consistent with supposed situation, it is judged that result is correct.

Embodiment 2: 110kV/35kV resonator system Xuhanting oral solution phantom as shown in Figure 1, its parameter elaborates in embodiment 1, is described again here.It is now assumed that system generation Xuhanting oral solution.Under the model, emulation obtains during Xuhanting oral solution zero sequence voltage on neutral point value as shown in Figure 5.The residual voltage data of window during 5ms after selecting device startup, ask for first-order difference and the second differnce of residual voltage data, with d [2] (n) for transverse axis, with d [1] (n) for longitudinal axis formation level, ask for the quadratic sum of consecutive points distance in this plane.

As described in Example 1, for this model by a large amount of emulation experiments, criterion can be set up: if dist2_sum> 1, then it is judged as earth fault；If dist2_sum≤ 1, then it is judged as Xuhanting oral solution.Calculating obtains dist2_sum=0.09, dist2_sum≤ 1 it is determined that be Xuhanting oral solution, consistent with supposed situation, it is judged that result is correct.

Above in conjunction with accompanying drawing, the specific embodiment of the present invention is explained in detail, but the present invention is not limited to above-mentioned embodiment, in the ken that those of ordinary skill in the art possess, it is also possible to make various change under the premise without departing from present inventive concept.

Claims (1)

1. the power distribution network Xuhanting oral solution recognition methods of consecutive points distance in the plane constituted based on adjacent difference of residual voltage, it is characterized in that: when the power distribution network of neutral by arc extinction coil grounding breaks down, distribution bus residual voltage data in short time-window after extraction fault or Xuhanting oral solution, ask for first-order difference and the second differnce of residual voltage data, with first-order difference and second differnce formation level, ask for the quadratic sum of consecutive points distance in this plane, according to the size of consecutive points square distance sum, Xuhanting oral solution and singlephase earth fault are differentiated；

Described method specifically comprises the following steps that

(1) after distribution network line generation singlephase earth fault or Xuhanting oral solution, line selection apparatus starts and records ripple immediately, records bus residual voltage；

(2) extraction is broken down or the residual voltage data u in short time-window after Xuhanting oral solution₀N (), calculates first-order difference d [1] (n) and second differnce d [2] (n):

D [1] (n)=u₀(n)-u₀(n-1)

D [2] (n)=d [1] (n)-d [1] (n-1)

In formula, n is discrete data the n-th sampled point；

(3) with d [2] (n) for transverse axis, construct adjacent order differential planar with d [1] (n) for the longitudinal axis, ask for square dist2 (n) of consecutive points distance in this plane²；

dist2(n)²=[d [2] (n)-d [2] (n-1)]²+[d[1](n)-d[1](n-1)]²

(4) to data dist2 (n)²Summation, tries to achieve dist2_sum:

$dist{2}_{sum}=\underset{n=1}{\overset{N}{\Σ}}dist2{\left(n\right)}^2$

In formula: N is total number of sample points；

(5) dist2 is judged_sumSize；

If dist2_sumIf greater than 1, then it is earth fault；

If dist2_sumLess than or equal to 1, then it it is Xuhanting oral solution.