CN105954640A - Power distribution network fault line selection method based on dominant frequency zero sequence power - Google Patents

Abstract

The invention discloses a power distribution network fault line selection method based on dominant frequency zero sequence power, aiming to solve the problem that when a complex small current grounding system generates a single-phase earth fault, present line selection methods based on dependency may cause misjudgment due to insufficient criterion margin. In order to solve the problem of insufficient criterion margin, the invention provides a power distribution network fault line selection method based on dominant frequency zero sequence power, which selects lines by employing dominant frequency zero sequence power as characteristic quantity, and calculates the dominant frequency zero sequence power integrated correlation coefficient corresponding to each feeder line, wherein a fault line integrated correlation coefficient is less than zero, and a perfect line integrated correlation coefficient is greater than zero. A lot of simulation results show that the method increases line selection criterion margin and line selection accuracy, and is not influenced by switching angles and fault resistors.

Description

Distribution network fault line selection method based on dominant frequency homopolar power

Technical field

The invention belongs to distribution network fault line selection method technical field, be specifically related to a kind of based on dominant frequency homopolar power join Electric network fault selection method.

Background technology

Distribution net work structure is complicated, and existing fault-line selecting method has limited.Such as injecting signal, available signal Detection device failure judgement circuit, but need to install signal injection device, output investment ratio is relatively big, and by intermittent electric arc and fault electricity The impact of resistance；Zero sequence admittance method utilizes the change of admittance coefficient before and after every line fault to carry out failure line selection, but it needs to disappear Arc coil is together with the use of, restricted application；First half-wave method utilizes faulty line and the wave head polarity first perfecting circuit Contrary principle route selection, but collecting device is required too high；Zero-sequence current correlational analysis method may utilize faulty line zero-sequence current Comprehensive dependency is little and perfects the big principle of the comprehensive dependency of circuit and carries out route selection, but criterion nargin is the most too low, easily causes Erroneous judgement.Pertinent literature propose dependency selection method based on wavelet packet owing to there is the problem of wavelet basis selection, because of This haves much room for improvement.Homopolar power correlational analysis method utilizes the fault section principle in opposite direction with non-faulting waveform at localization method The comparison applied is many, owing to homopolar power introduces homopolar power signal relative to zero-sequence current, can avoid in practice When using zero sequence current signal as characteristic quantity route selection, weak output signal produces erroneous judgement problem.

Summary of the invention

Present invention solves the technical problem that and there is provided a kind of distribution network fault line selection method based on dominant frequency homopolar power, It is the New Criterion of Faulty Line Detection for Distribution based on dominant frequency homopolar power utilizing prony algorithm to propose, utilizes faulty line dominant frequency Homopolar power polarity is with to perfect line polarity contrary, and then can carry out route selection by dominant frequency homopolar power integrated correlation coefficient, this side Method improves failure criterion nargin and locating accuracy to a great extent, is more suitable for baroque distribution network system.

The present invention solves that above-mentioned technical problem adopts the following technical scheme that, distribution network failure based on dominant frequency homopolar power Selection method, it is characterised in that concretely comprise the following steps:

Step 1, whether detection zero-sequence current is more than the system nominal phase voltage maximum of 0.15 times in real time, if as then entered Row step 2；

Step 2, utilizes prony algorithm to extract bus dominant frequency residual voltage and each feeder line dominant frequency zero-sequence current；

Step 3, is multiplied with each feeder line dominant frequency zero-sequence current respectively by dominant frequency residual voltage and calculates corresponding to each feeder line Dominant frequency zero sequence frequency；

Step 4, utilizes formulaCalculate two between each feeder line dominant frequency homopolar power biphase Close coefficient, q in formula_0zx, q_0zyRepresenting feeder line x, the dominant frequency homopolar power corresponding to y respectively, n=1 represents that fault occurs moment, N For signal data length, finally give matrixρ_ijRepresent i-th feeder line and j-th strip Correlation coefficient between feeder line dominant frequency homopolar power, l represents total number of feeder line；

Step 5, utilizes formulaCalculate each feeder line dominant frequency homopolar power integrated correlation coefficient；

Step 6, the feeder line corresponding to minus integrated correlation coefficient is faulty line, if integrated correlation coefficient is both greater than Zero is bus-bar fault.

The present invention carrys out route selection using dominant frequency homopolar power as characteristic quantity, calculates the dominant frequency homopolar power corresponding to each feeder line Integrated correlation coefficient, wherein faulty line integrated correlation coefficient is less than zero, and perfects circuit integrated correlation coefficient more than zero.In a large number Simulation result shows, the method improves route selection criterion nargin and route selection accuracy rate to a certain extent, and not by switching angle and The impact of fault resstance.

Accompanying drawing explanation

Fig. 1 is the phantom figure of the present invention；

Fig. 2 is each circuit dominant frequency homopolar power when being switching angle 0 degree, fault resstance 5 Ω in the present invention；

Fig. 3 is each circuit dominant frequency homopolar power when being switching angle 0 degree, fault resstance 5000 Ω in the present invention.

Detailed description of the invention

By the following examples the foregoing of the present invention is described in further details, but this should be interpreted as this The scope inventing above-mentioned theme is only limitted to below example, and all technology realized based on foregoing of the present invention belong to this Bright scope.

Embodiment

1, the extraction of principal frequency component

Prony algorithm now in the extraction of principal frequency component use the most ripe, it be by a series of amplitude, frequently Rate, phase place, the algorithm of linear fit of complex-exponential function of decay factor.Assume there be k transient state input quantity y (0), y (0) ..., Y (k-1), then utilize m exponential function to carry out the expression formula of matching input quantity as follows:

$b_s=A_s{e}^{{\mathrm{j\θ}}_s}---\left(1\right)$

$z_s=e^{({\mathrm{\α}}_s+j2{\mathrm{\πf}}_s)\mathrm{\Δ}t}---\left(2\right)$

$\hat{y}\left(i\right)=\underset{s=1}{\overset{m}{\Σ}}{b}_s{z}_s^i---\left(3\right)$

A in formula_sFor amplitude, θ_sFor initial phase angle, α_sFor decay factor, f_sFor frequency, Δ t is time interval.Pass through document (Huang Yunjiang, Xie Weibo. high accuracy harmonic detecting [J] based on Iterative Prony Method, electrical applications, 2007,26 (4): 96- 100；Liu Yingmei, high pure as jade. Transient Disturbance Signal Analysis based on Prony method [J], electric power network technique 2006,30 (4), 26-30) In step can obtain the amplitude of m group, frequency, phase place, decay factor.M group data are substituted in formula (1)-(3) respectively, can obtain To m component.Definition herein utilizes that the counted component of group data in m group corresponding to amplitude maximum to be principal frequency component, institute Corresponding frequency is called basic frequency.Need to extract dominant frequency homopolar power herein, therefore can be by zero-sequence current and zero-sequence current be believed Number carry out prony algorithm matching, extract corresponding dominant frequency zero-sequence current and dominant frequency residual voltage to ask for dominant frequency homopolar power, as Shown in lower:

q_0z(n)=u_0z(n)*i_0z(n), n=1,2 ..., N (4)

Wherein i_0z, u_0z, q_0zRepresent dominant frequency zero-sequence current, dominant frequency residual voltage and dominant frequency homopolar power respectively.

2, location design

By document (Zhang Xinhui, Pan Xinyu, He Baina, etc. based on transient state dominant frequency zero mould failure of the current route selection emulation grind Study carefully [J]. Computer Simulation, 2013,30 (10): 157-162) understand the dominant frequency zero-sequence current advanced bus dominant frequency zero perfecting circuit Sequence voltage 90 degree, the dominant frequency zero-sequence current delayed bus dominant frequency residual voltage 90 degree of faulty line, it may thus be appreciated that perfect circuit The phase place of dominant frequency homopolar power is to differ 180 degree with the dominant frequency homopolar power of faulty line, then understand the dominant frequency perfecting circuit Correlation coefficient between the dominant frequency homopolar power of homopolar power and faulty line is negative, and every two dominant frequency zero sequences perfecting circuit Correlation coefficient between power is just, therefore may utilize integrated correlation coefficient and carrys out route selection as criterion.

General correlation coefficient describes the similarity degree of two signals.Dominant frequency zero corresponding to the most any two feeder lines Correlation coefficient between sequence power is designated as ρ, is represented by:

$\mathrm{\ρ}=\frac{\underset{n=1}{\overset{N}{\Σ}}{q}_{0zx}\left(n\right)q_{0zy}\left(n\right)}{\sqrt{\underset{n=1}{\overset{N}{\Σ}}{q}_{0zx}^2\left(n\right)\underset{n=1}{\overset{N}{\Σ}}{q}_{0zy}^2\left(n\right)}}---\left(5\right)$

Q in formula_0zx, q_0zyRepresent feeder line x, the dominant frequency homopolar power corresponding to y respectively.N=1 represents that fault occurs moment, N For signal data length.Owing to zero sequence current mutual inductor is easily saturated after fault occurs 1/4 cycle, therefore the most only choosing The data taken in fault generation rear 1/10 cycle carry out correlation analysis, this also reduces operational data, improve route selection Efficiency.

The correlation coefficient two-by-two between each feeder line dominant frequency homopolar power can be tried to achieve, then can be correlated with by formula (5) Coefficient matrix is as follows:

$B=\left[\begin{array}{ccccc}{\mathrm{\ρ}}_{11}& \mathrm{...}& {\mathrm{\ρ}}_{1j}& \mathrm{...}& {\mathrm{\ρ}}_{1l}\\ .& & .& & .\\ .& & .& & .\\ .& & .& & .\\ {\mathrm{\ρ}}_{i1}& \mathrm{...}& {\mathrm{\ρ}}_{ij}& \mathrm{...}& {\mathrm{\ρ}}_{il}\\ .& & .& & .\\ .& & .& & .\\ .& & .& & .\\ {\mathrm{\ρ}}_{l1}& \mathrm{...}& {\mathrm{\ρ}}_{lj}& \mathrm{...}& {\mathrm{\ρ}}_{ll}\end{array}\right]$

ρ_ijRepresenting the correlation coefficient between i-th feeder line and j-th strip feeder line dominant frequency homopolar power, l represents total of feeder line Number.The average that integrated correlation coefficient is the correlation coefficient between i-th feeder line and other feeder lines of definition i-th, the i.e. i-th row unit The average of element, the integrated correlation coefficient formula corresponding to every circuit is represented by:

${\mathrm{\ρ}}_i=\frac{1}{l}\underset{j=1}{\overset{l}{\Σ}}{\mathrm{\ρ}}_{ij}---\left(6\right)$

When there is singlephase earth fault in distribution network line, the minus feeder line of integrated correlation coefficient is faulty line, if Both greater than zero is bus-bar fault.Concrete route selection step is as follows:

1) real-time detection zero-sequence current whether system nominal phase voltage maximum more than 0.15 times, if as then carried out the Two steps；

2) prony algorithm is utilized to extract bus dominant frequency residual voltage and each feeder line dominant frequency zero-sequence current；

3) it is multiplied with each feeder line dominant frequency zero-sequence current respectively by dominant frequency residual voltage and calculates the master corresponding to each feeder line Frequently zero sequence frequency；

4) utilize formula (5) to calculate the correlation coefficient two-by-two between each feeder line dominant frequency homopolar power, obtain matrix B；

5) formula (6) is utilized to calculate each feeder line dominant frequency homopolar power integrated correlation coefficient；

6) feeder line corresponding to minus integrated correlation coefficient is faulty line；If integrated correlation coefficient is both greater than zero, It it is bus-bar fault.

3 sample calculation analysis

EMTP is utilized to build the power distribution network of 110kv/10kv through grounding through arc model as it is shown in figure 1, wherein make somebody a mere figurehead Circuit and cable-line parameter be incorporated in list of references (Kang little Ning, Liu Xin, Suo Nanjiale, etc. based on matrix pencil algorithm through disappearing Arc coil grounding system fault route selecting new method [J]. Automation of Electric Systems, 2012,36 (12): 88-93)；Every feedback herein Line is all connected to load, replaces with the impedance of a 400+j20 Ω；Arc suppression coil uses overcompensation mode to run, and compensativity is 8%, arc suppression coil inductance value is 0.982H；Sample frequency is 100kHz, and simulation time is set to 0.04s, and single-phase earthing event occurs The barrier moment is 0.02s.

3.1 analysis of simulation result

Singlephase earth fault is respectively occurring at 10% and the 90% of circuit 1, switching angle 0 degree and 90 degree time result carry out Analysis verification, only provides singlephase earth fault as space is limited, respectively and switching angle 0 degree, fault at the 10% of circuit 1 occurs Resistance is 5 Ω and the dominant frequency zero-sequence current that extracts at each circuit when switching angle 0 degree, fault resstance 5000 Ω and at bus Extracting dominant frequency residual voltage as shown in table 1, the dominant frequency residual voltage of bus with the product of the dominant frequency zero-sequence current of each circuit is For each circuit dominant frequency homopolar power as shown in Figure 2,3.By Fig. 2,3 understand and perfect the dominant frequency homopolar power of circuit 2,3,4 and divide The direction with the dominant frequency homopolar power of faulty line 1 is not contrary, and the dominant frequency zero sequence power direction perfecting circuit 2,3,4 is It is identical, it may thus be appreciated that the method applies the effect on this phantom fine.

For the feasibility of checking the method more further, list every obtained by corresponding simulated conditions herein The integrated correlation coefficient of feeder line is as shown in table 2, and the method is designated as method one.In order to relatively dominant frequency homopolar power in this paper is made The advantage of the amount of being characterized, have also been made herein and carrys out route selection using traditional homopolar power as characteristic quantity, and the method is designated as method two, knot Fruit is as shown in table 3.

By table 2, use basic frequency homopolar power route selection effect fine, perfect circuit basic frequency homopolar power institute right The integrated correlation coefficient answered is very big, and the integrated correlation coefficient corresponding to faulty line basic frequency homopolar power is the least, so its Criterion nargin is very big, and is not affected by fault resstance, abort situation, switching angle, the most there is not the phenomenon of erroneous judgement.Pass through table 3 understand, if analyzing its comprehensive dependency just with traditional homopolar power as characteristic quantity, its criterion nargin is big not, If there is disturbance in the external world, then it is easy to misjudgment phenomenon.

Table 1 principal frequency component parameter

3.2 bus-bar fault analyses

In order to check based on dominant frequency homopolar power, do bus herein and there occurs that when switching angle is 0 degree transition resistance is 5 Ω, 50 Ω, 500 Ω, 4 kinds of single-phase earthing situations of 5000 Ω, the integrated correlation coefficient of each feeder line dominant frequency homopolar power obtained As shown in table 4.

Simulation result shows, power distribution network route selection new method based on dominant frequency homopolar power in this paper is adapted to bus event Barrier differentiates, criterion nargin is bigger, is not susceptible to erroneous judgement.

Table 2 utilizes dominant frequency homopolar power integrated correlation coefficient route selection result

Table 3 utilizes tradition homopolar power integrated correlation coefficient route selection result

The integrated correlation coefficient of each feeder line dominant frequency homopolar power during table 4 bus-bar fault

4, conclusion

This paper presents the method utilizing the integrated correlation coefficient route selection between each feeder line dominant frequency homopolar power, its criterion is abundant Degree is relatively big, is susceptible to external interference and the phenomenon of erroneous judgement occurs, can effectively determine fault feeder, and not by fault resstance, Fault close angle, the impact of abort situation, be suitable for baroque distribution network system.

Embodiment above describes the ultimate principle of the present invention, principal character and advantage, the technical staff of the industry should Understanding, the present invention is not restricted to the described embodiments, and the simply explanation present invention's described in above-described embodiment and description is former Reason, under the scope without departing from the principle of the invention, the present invention also has various changes and modifications, and these changes and improvements each fall within In the scope of protection of the invention.

Claims (1)

1. distribution network fault line selection method based on dominant frequency homopolar power, it is characterised in that concretely comprise the following steps:

Step 1, whether detection zero-sequence current is more than the system nominal phase voltage maximum of 0.15 times in real time, if as then walked Rapid 2；

Step 2, utilizes prony algorithm to extract bus dominant frequency residual voltage and each feeder line dominant frequency zero-sequence current；

Step 3, is multiplied with each feeder line dominant frequency zero-sequence current respectively by dominant frequency residual voltage and calculates the master corresponding to each feeder line Frequently zero sequence frequency；

Step 4, utilizes formulaCalculate the phase relation two-by-two between each feeder line dominant frequency homopolar power Number, q in formula_0zx, q_0zyRepresenting feeder line x, the dominant frequency homopolar power corresponding to y respectively, n=1 represents that fault occurs the moment, and N is letter Number length, finally gives matrixρ_ijRepresent i-th feeder line and j-th strip feeder line Correlation coefficient between dominant frequency homopolar power, l represents total number of feeder line；

Step 5, utilizes formulaCalculate each feeder line dominant frequency homopolar power integrated correlation coefficient；

Step 6, the feeder line corresponding to minus integrated correlation coefficient is faulty line, if integrated correlation coefficient is both greater than zero, It it is bus-bar fault.