CN104950216A - Waveform comparison based power distribution line fault positioning method - Google Patents

Abstract

The invention belongs to the field of power distribution network fault positioning for electric power systems, relates to the technical field of fault positioning of closed-loop lines or distributed generation access lines, in particular to a waveform comparison based power distribution line fault positioning method. An FTU (feeder terminal unit) with a distributed control function is adopted for real-time detection of fault currents; in a short-circuit fault, the fault current of a detection point is compared with the fault current of an adjacent detection point to determine a fault section according to a waveform polarity relation. By the waveform comparison based power distribution line fault positioning method, correct positioning of phase faults can be realized in closed-loop lines or distributed generation access lines, and fault positioning can be completed before relay protection actions. In addition, the method is applicable to quick positioning of short-circuit faults of power distribution networks, and adoption of a terminal unit for voltage signal acquisition is not needed.

Description

A kind of distribution line failure localization method based on waveform comparison

Technical field

The invention belongs to system for distribution network of power localization of fault field, particularly relate to the Fault-Locating Test field of closed loop configuration circuit or a large amount of line attachment of distributed power source, be specifically related to a kind of distribution line failure localization method based on waveform comparison.

Background technology

Along with power distribution network is to the iterative method of intelligent distribution network, increasing operation with closed ring circuit, distributed power source (distributed generation, DG) power distribution network is accessed, this affects greatly distribution network failure location, traditional Fault Locating Method is even caused to lose efficacy, intelligent distribution network requires higher to power supply reliability, after breaking down, require to realize fault isolation and fault recovery fast, power with isolated fault region, recovery non-faulting dead electricity district, and localization of fault is the prerequisite and the basis that realize fault isolation and fault recovery.Therefore, the distribution network failure location containing operation with closed ring circuit, distributed power source becomes the hot issue of power distribution network research.Traditional Fault Locating Method mainly contains: matrix method, traveling wave method etc.These methods or be not suitable for operation with closed ring circuit, power distribution network containing distributed power source, or need detection failure direction of current, the intelligent distribution network be not all suitable for.The feeder line of existing power distribution network does not generally install voltage transformer (VT), so the direction of current of feeder line is difficult to judge.Along with FTU and powerline network are gradually become strong, between FTU (ca bin: Feeder Terminal Unit, FTU), a large amount of information interactions can be carried out.Therefore, rely on the information interaction between FTU, realize distribution network failure by FTU and locate and become possibility, herein with reference on existing electrical power distribution network fault location method basis, utilize the information interaction of adjacent check point FTU, propose the electrical power distribution network fault location method based on waveform comparison.

Summary of the invention

Object of the present invention is the problems referred to above solving prior art, provide a kind of distribution line failure localization method based on waveform comparison, the invention solves closed circuit, distributed power source access and cannot the short trouble orientation problem in calculating current direction owing to not configuring PT, with reference on existing electrical power distribution network fault location method basis, utilize the information interaction of adjacent check point FTU, propose the electrical power distribution network fault location method based on waveform comparison, because fault location algorithm is realized by the feeder terminal unit with distributed coordination function, can calculate fast, localization of fault can be completed before relay protection action, be applicable to the rapid cut-off localization of fault of power distribution network, utilize ca bin (Feeder Terminal Unit, FTU) phase current of each check point is detected in real time, during short trouble, according to each check point phase current polarity relativeness, judge fault section, to achieve these goals, the technical solution used in the present invention is as follows:

Based on a distribution line failure localization method for waveform comparison, it is characterized in that: when distribution line normally runs, FTU detects the phase current of each check point in real time, when distribution line is short-circuited fault, carries out localization of fault according to the following steps:

Step S1., when detecting that phase current exceedes preset threshold, gets the signal of a cycle after fault half cycle in faulted phase current sample sequence;

Step S2. establishes circuit to have m FTU, is divided into m section, wherein m >=2 by circuit;

The current signal of a jth FTU check point fault phase cycle and the fault-current signal of adjacent jth+1 FTU check point same fault phase cycle are calculated its electric current related coefficient Δ ρ by step S3. _j,

$\mathrm{\Δ}{\mathrm{\ρ}}_j=\frac{\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{i}_{\mathrm{jp}}\left(k\right)i_{(j+1)p}\left(k\right)}{\sqrt{\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{i}_{\mathrm{jp}}^2\left(k\right)\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{i}_{(j+1)p}^2\left(k\right)}},$

In formula, i _jp(k) and i _{(j+1) p}k () is respectively a jth FTU and jth+1 FTU check point fault current sample sequence, wherein 0 < j≤m-1; N is the data length of sampling fault-current signal;

Step S4. is by Δ ρ _jwith setting value ρ ₀compare, judge fault section, and localization of fault result is uploaded to controlling center, the timely handling failure of prompting staff.

Preferably, according to Δ ρ _jwith setting value ρ ₀compare, judge fault section, judge as follows:

(1) if+1 the monitoring point polarity of wave in a jth monitoring point and jth is identical, i.e. Δ ρ _j> ρ ₀, then judge that section j is as perfecting section;

(2) if+1 the monitoring point polarity of wave in a jth monitoring point and jth is contrary, i.e. Δ ρ _j< ρ ₀, then judge that section j is as fault section;

(3) if front m-1 section both sides check point current waveform polarity is all identical, Δ ρ _j> ρ ₀(0 < j≤m-1), then the last section is fault section.

Preferably, during the fault that is short-circuited in described circuit, FTU is according to current change quantity signal enabling, and FTU records the current signal of each check point 2 ~ 5 cycles.

In sum, the present invention also has following beneficial effect:

Utilize the information interaction of adjacent check point FTU, propose the electrical power distribution network fault location method based on waveform comparison.Because fault location algorithm is realized by the feeder terminal unit with distributed coordination function, can calculate fast, localization of fault can be completed before relay protection action, be applicable to the rapid cut-off localization of fault of power distribution network.

Accompanying drawing explanation

In order to be illustrated more clearly in example of the present invention or technical scheme of the prior art, introduce doing accompanying drawing required in embodiment or description of the prior art simply below, apparently, accompanying drawing in the following describes is only examples more of the present invention, to those skilled in the art, do not paying under creationary prerequisite, other accompanying drawing can also obtained according to these accompanying drawings.

Fig. 1 is the distribution network automated positioning system structure schematic diagram of a kind of distribution line failure localization method based on waveform comparison of the present invention.

Fig. 2 is the positioning flow figure of a kind of distribution line failure localization method based on waveform comparison of the present invention.

Fig. 3 is the distribution line realistic model figure of a kind of distribution line failure localization method based on waveform comparison of the present invention.

Fig. 4 is A phase current waveform comparison diagram in distribution network automated positioning system of the present invention.

Fig. 5 is B phase current waveform comparison diagram in distribution network automated positioning system of the present invention.

Embodiment

Below in conjunction with the accompanying drawing in example of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

As shown in Figure 1, give Intelligent feeder line automation system (the feeder automation containing distributed power source in the present invention, FA), comprise controlling center, communication network and FTU and (comprise remote terminal unit (remote terminal unit, RTU), all information interaction can be realized between described controlling center and end device and between end device, and each end device all can perform distributed AC servo system, realize localization of fault, fault isolation and fault recovery; Composition graphs 2, a kind of distribution line failure localization method based on waveform comparison, carries out localization of fault according to the following steps:

First, when normally running, distribution line is undertaken by following workflow: each FTU in circuit detects each phase current in real time, compare with predetermined threshold level, judge whether equality circuit entry condition, during normal work, main website can carry out status poll to FTU, and avoiding device is deactivated state.

Secondly, when breaking down, distribution line is undertaken by following workflow: during the fault that is short-circuited in circuit, FTU is according to current change quantity signal enabling, record the current signal of each check point 2 ~ 5 cycles, each FTU carries out fault section location according to fault data, carries out localization of fault according to the following steps:

Step S1., when detecting that phase current exceedes jump-value of current preset threshold, gets the signal of a cycle after fault half cycle in faulted phase current sample sequence; The present invention adopts the localization of fault start-up criterion based on jump-value of current;

Step S2. establishes circuit to have m FTU, is divided into m section, wherein m >=2 by circuit;

The current signal of a jth FTU check point fault phase cycle and the fault-current signal of adjacent jth+1 FTU check point same fault phase cycle are calculated its electric current related coefficient Δ ρ by step S3. _j,

$\mathrm{\&Delta;}{\mathrm{\&rho;}}_j=\frac{\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{i}_{\mathrm{jp}}\left(k\right)i_{(j+1)p}\left(k\right)}{\sqrt{\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{i}_{\mathrm{jp}}^2\left(k\right)\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{i}_{(j+1)p}^2\left(k\right)}},$

In formula, i _jp(k) and i _{(j+1) p}k () is respectively a jth FTU and jth+1 FTU check point fault current sample sequence, wherein 0 < j≤m-1; N is the data length of sampling fault-current signal;

Step S4. is by Δ ρ _jwith setting value ρ ₀(ρ ₀for related coefficient threshold value, generally get ρ ₀=0) compare, judge fault section, and localization of fault result is uploaded to controlling center, the timely handling failure of prompting staff, judge fault section, judge as follows:

(1) if+1 the monitoring point polarity of wave in a jth monitoring point and jth is identical, i.e. Δ ρ _j> ρ ₀, then judge that section j is as perfecting section;

(2) if+1 the monitoring point polarity of wave in a jth monitoring point and jth is contrary, i.e. Δ ρ _j< ρ ₀, then judge that section j is as fault section;

(3) if front m-1 section both sides check point current waveform polarity is all identical, Δ ρ _j> ρ ₀(0 < j≤m-1), then the last section is fault section.

Finally, after judging fault section, carry out troubleshooting process immediately: if judge fault section, then localization of fault result is uploaded to controlling center, the timely handling failure of prompting staff, in the present invention, as shown in Figure 3, arrange k1 point to be short-circuited fault, verify the validity of above-mentioned algorithm, in this model, have six outlets, wherein, with circuit L6 for loop wire, k1 point is A, B two-phase short-circuit fault in circuit L6, i _61afor A phase FUT1 check point electric current in circuit L6, i _61bfor the electric current of B phase FUT1 check point in circuit L6; i _62afor the electric current of A phase FUT2 check point in circuit L6, i _62bfor the electric current of B phase FUT2 check point in circuit L6; i _63afor the electric current of A phase FUT3 check point in circuit L6, i _63bfor the electric current of B phase FUT3 check point in circuit L6.

When the current i of check point _61a, i _61b, i _62a, i _62b, i _63a, i _63ball meet entry condition, be greater than threshold value, namely fault current detected, other check points all do not detect fault current, therefore, calculate i _61aand i _62a, i _61band i _62b, i _62aand i _63a, i _62band i _63bbetween electric current related coefficient, calculated value is as shown in table 1, as shown in Table 1, i _61aand i _62a, i _61band i _62bbetween related coefficient be all greater than 0, there is no fault between check point FTU1 and FTU2; And i _62aand i _63a, i _62band i _63bbetween related coefficient be all less than 0, trouble spot is between check point FUT2 and FUT3, and fault phase is A, B two-phase, and localization of fault is correct.

Related coefficient between table 1 fault current

As Fig. 4 and Fig. 5 simulation result represents, i _61a, i _62ain the same way, with i _63aoppositely, i _61b, i _62bin the same way, with i _63boppositely, show that fault is between check point FUT2 and FUT3, be A, B two-phase short-circuit fault, localization of fault is correct.

In sum, distribution network failure location of the present invention is the basis of fault isolation and fault recovery, operation with closed ring circuit, a large amount of distributed power source access makes fault current more complicated, and distribution feeder seldom installs voltage transformer (VT), this causes much traditional Fault Locating Method to lose efficacy, a kind of Fault Locating Method based on waveform comparison that the present invention proposes, by ca bin (the Feeder Terminal Unit with distributed coordination function, FTU) real-time detection failure electric current, during short trouble, the fault current of the fault current of this check point and adjacent check point is compared, utilize the polar relationship determination fault section of waveform, this method can in operation with closed ring circuit or distributed power source line attachment, realize the correct location of phase fault, and gather voltage signal without the need to terminal unit.

The foregoing is only the preferred embodiment of invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. based on a distribution line failure localization method for waveform comparison, it is characterized in that: when distribution line normally runs, FTU detects the phase current of each check point in real time, when distribution line is short-circuited fault, carries out localization of fault according to the following steps:

Step S1., when detecting that phase current exceedes jump-value of current preset threshold, gets the signal of a cycle after fault half cycle in faulted phase current sample sequence;

Step S2. establishes circuit to have m FTU, is divided into m section, wherein m >=2 by circuit;

The current signal of a jth FTU check point fault phase cycle and the fault-current signal of adjacent jth+1 FTU check point same fault phase cycle are calculated its electric current related coefficient Δ ρ by step S3. _j,

In formula, i _jp(k) and i _{(j+1) p}k () is respectively a jth FTU and jth+1 FTU check point fault current sample sequence, wherein 0 < j≤m-1; N is the data length of sampling fault-current signal;

Step S4. is by Δ ρ _jwith setting value ρ ₀compare, judge fault section, and localization of fault result is uploaded to controlling center, the timely handling failure of prompting staff.

2. a kind of distribution line failure localization method based on waveform comparison according to claim 1, is characterized in that: according to Δ ρ _jwith setting value ρ ₀compare, judge fault section, judge as follows:

(1) if+1 the monitoring point polarity of wave in a jth monitoring point and jth is identical, i.e. Δ ρ _j> ρ ₀, then judge that section j is as perfecting section;

(2) if+1 the monitoring point polarity of wave in a jth monitoring point and jth is contrary, i.e. Δ ρ _j< ρ ₀, then judge that section j is as fault section;

(3) if front m-1 section both sides check point current waveform polarity is all identical, Δ ρ _j> ρ ₀(0 < j≤m-1), then the last section is fault section.

3. a kind of distribution line failure localization method based on waveform comparison according to claim 1, it is characterized in that: during the fault that is short-circuited in described circuit, FTU is according to current change quantity signal enabling, and FTU records the current signal of each check point 2 ~ 5 cycles.