Substation area backup protection method based on combination of direction comparison and current differential

A backup protection, current differential technology, applied in emergency protection circuit devices, electrical components and other directions, can solve the problems of high bandwidth and reliability requirements of communication networks, increased calculation, and high economic costs, and achieves simplified configuration and tuning. The effect of shortening the action time and increasing the action speed

Active Publication Date: 2014-05-07
STATE GRID CORP OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0004] In order to improve the performance of backup protection, some new methods of relay protection have been widely studied, such as wide-area protection, collective protection, system protection, integrated protection, etc.; the above-mentioned new methods have the following problems: 1) The acquisition of wide-area information depends on the phasor Measurement unit (PMU) and wide-area synchrophasor measurement system (WAMS) are too costly to implement in medium and low-voltage power grids; 2) No matter whether a centralized structure or a distributed structure is adopted, there is a problem of how to determine the protection area; 3) In order to limit the scope of fault influence to the minimum, it is necessary to further theoretically study the optimal tripping strategy when the regional power grid is faulty; 4) Accurate acquisition of wide-area synchronization information for relay protection requires extremely high bandwidth and reliability of the communication network
[0007] Invention patent (application number: 201210094854.1) "Station domain backup protection method based on current differential principle" discloses a station domain backup protection method based on current differential principle. The method used to determine the fault point is to completely rely on " Current differential principle”, this method requires that all the currents within the protection range are sampled values ​​at the same time, this requirement is easy to meet inside the substation, but it is difficult to meet when obtaining the sampled value information between substations, therefore, the invention It cannot work when the synchronous sampling value information between substations is missing; when determining the external fault of the substation, the invention adopts the method of reducing the protection components one by one, which will calculate the differential current and braking current multiple times, increasing the amount of calculation , will put forward higher requirements for the realization of software and hardware

Method used

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  • Substation area backup protection method based on combination of direction comparison and current differential
  • Substation area backup protection method based on combination of direction comparison and current differential
  • Substation area backup protection method based on combination of direction comparison and current differential

Examples

Experimental program
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Effect test

Embodiment 1

[0052] Take the working condition of line L5 fault and main protection refusing to operate as an example. When F 1 If a fault occurs at any point, the fault starting element will act, and the backup protection of the station domain will enter the fault handling procedure. After calculating the current differential criterion, it is detected that the differential zone B of the substation is in the braking state of the differential criterion, so it is judged that the fault occurs outside the substation. There are two situations at this time: in the first case, the fault is located on the outgoing line of the substation; in the second case, the fault is located outside the protection range of the station domain backup protection. The station domain backup protection judges the directional element according to the collected bus voltage and outgoing current. The judgment result of the direction of the outgoing line L5 is the positive direction, while the direction judgment results ...

Embodiment 2

[0053] Embodiment 2: Take the internal failure of transformer T1 and the refusal of circuit breaker CB12 as an example to illustrate the specific process:

[0054] f 2 A fault occurs at the fault, the fault start element acts, and the station domain backup protection enters the fault processing procedure:

[0055] After the calculation of the current differential criterion, it is detected that the differential zone B of the substation is in the action state of the differential criterion, and it is determined that the faulty element is located inside the substation;

[0056] Enter the traversal program of the extended differential area for component faults in the station, and remove the busbars Bus01, Bus02, Bus03, Bus04, Bus05, Bus06 and transformer T2 in the differential area B in the station in sequence, and the extended differential area formed during this process Zones are all in the action state of the differential criterion, so it is determined that the fault is located...

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Abstract

The invention discloses a substation area backup protection method based on combination of direction comparison and current differential. In the method, zoning processing is performed on a backup protection range so that an application status that backup protection relies on fault electric quantity and time-limit ladder cooperation to realize selectivity is changed and the movement speed of the backup protection is improved; a current differential principle and a direction comparison principle are used comprehensively for fault positioning so that not only is absolute selectivity of the differential principle is used, but advantages that direction elements have lower demands on sampling value data synchronization are used, and at the same time, performance demands on inter-station data channels are reduced; after system faults are detected, time delay for Nms is performed to wait for a main protection motion, wherein N belongs to a range of [250, 350]; if the main protection refuses to move, a backup tripping command is sent out; and if a circuit breaker is out of order, an out-of-order tripping command is sent to an expansion tripping area. Compared with ladder time delay of at least 500ms for one differential adopted by traditional backup protection, the method is faster in motion rapid.

Description

technical field [0001] The invention relates to the field of electric power system relay protection, in particular to a station domain backup protection method based on the combination of direction comparison and current differential. Background technique [0002] The purpose of the application of power system relay protection technology is to automatically and quickly remove the faulty equipment when the power grid fails, and to limit the scope of the fault to the smallest area, so as to ensure the normal operation of the fault-free part of the power grid. The basic principles of fault isolation include fast performance, selectivity, sensitivity, and reliability. According to the protection range and action characteristics, power system relay protection can be divided into two types: main protection and backup protection: the main protection can respond to various faults of the protected equipment and remove the fault in the shortest possible time limit (instantaneous); whe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/22
Inventor 苏建军张荣华崔德民刘建李晓博卢泽光张波陈钰高厚磊刘益青
Owner STATE GRID CORP OF CHINA
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