Method for judging and protecting low voltage in transformer short circuit fault

A short-circuit fault, low-voltage technology, applied in emergency protection circuit devices, instruments, measuring electricity and other directions, can solve the problems of low sensitivity, complex hardware, and many channels of traditional solutions, and achieve high action sensitivity, simple hardware, and few channels. Effect

Inactive Publication Date: 2010-08-11
XJ ELECTRIC +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

when When a two-phase short circuit occurs on the side or the △ side, although the sensitivity of the traditional scheme is very high, but When the side is a neutral point grounding system, a single-phase grounding short circuit occurs, The various line voltages on the side and the △ side are high, the sensitivity of the traditional scheme is very low or even refused to move, and the joint low-voltage start-up of the line voltage on both sides or three sides The traditional scheme needs to protect many channels and complex hardware

Method used

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  • Method for judging and protecting low voltage in transformer short circuit fault
  • Method for judging and protecting low voltage in transformer short circuit fault
  • Method for judging and protecting low voltage in transformer short circuit fault

Examples

Experimental program
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Effect test

Embodiment 1

[0025] The steps of identifying low voltage in transformer short circuit fault are as follows:

[0026] (1) Protection device measurement Three-phase phase voltage of the high voltage side (Y side) of the wiring transformer ;

[0027] (2) The protection device calculates the modulus of the Y-side line voltage: , , , The modulus of the Y-side phase voltage: =| |, =| |, =| |;

[0028] (3) Put , , , , , Six low voltage start criteria , , , , , ,among them Is the setting value, and then forms an "OR" gate output, when any of the six low voltages is less than the setting value If the criterion is met, the output level is "1", such as figure 1 Shown.

[0029] transformer side (AB two-phase short circuit), the fault point ; side (BC two-phase short circuit), ; side (CA two-phase short circuit), ; Because there must be a line voltage of zero, the low voltage start sensitivity is very high.

[0030] Transformer delta side outlet (AB two-phase short ci...

Embodiment 2

[0036] The steps to determine the low-voltage protection method in the transformer short-circuit fault are as follows:

[0037] (1) Protection device measurement Three-phase phase voltage of the high voltage side (Y side) of the wiring transformer ;

[0038] (2) The protection device calculates the modulus of the Y-side line voltage: , , , The modulus of the Y-side phase voltage: =| |, =| |, =| |;

[0039] (3) Put , , , , , Six low voltage start criteria , , , , , ,among them Is the setting value, and then forms an "OR" gate output, when any of the six low voltages is less than the setting value If the criterion is met, the output level is "1";

[0040] (4) The six “OR” gate outputs of the above six low-voltage start criteria and the over-current criteria form the “AND” gate delay outlet to trip the circuit breaker, such as figure 2 As shown, the low-voltage start-up of the transformer or the composite voltage start-up overcurrent protection ca...

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PUM

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Abstract

The invention relates to a method for judging and protecting low voltage in transformer short circuit fault, which comprises the following steps of: (1) measuring a phase voltage on one side of a wiring transformer by a protection device; (2) calculating a magnitude of line voltage between each two voltages on one side in the step (1) by the protection device; and (3) respectively comparing the magnitude of the phase voltage and the magnitude of the line voltage on one side in the step (2) with a setting value to form low voltage criterions, and forming an or gate output by all the low voltage criterions. After the application of the method, when all sides of the transformer are in a state of interphase short circuit and a neutral grounding system is in a state of single-phase grounding, one of the measured voltages is bound to be zero, the setting value can take a low value so as to ensure that a low voltage starting criterion can still have high action sensitivity and improve the reliability of non-maloperation during normal operation; and the low voltage setting value can enable a current setting value of an overcurrent criterion to take a low value so as to improve the action sensitivity of the overcurrent criterion. The invention has few channels to be protected and simple hardware.

Description

Technical field [0001] The invention relates to a method for identifying low voltage in a short-circuit fault of a transformer and a protection method thereof, and belongs to the field of power system relay protection. Background technique [0002] Current power system , Wired dual winding transformer and , , , There are three types of low-voltage startup schemes for the low-voltage startup overcurrent protection of the wired three-winding transformer: (1) Single-side low-voltage startup scheme for high-voltage side line voltage; (2) Single-side low-voltage startup scheme for high-voltage side phase voltage; (3) The high-voltage side line voltage and the low-voltage side line voltage form a joint low-voltage start scheme on both sides (three sides) of the OR gate output. when When a two-phase short circuit occurs on the side or delta side, although the sensitivity of the traditional scheme is very high, When the side is a neutral point grounding system, a single-phase gro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/04G01R31/02
Inventor 李瑞生姚晴林刘志远樊占峰刘星
Owner XJ ELECTRIC
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