Method for adjusting line protection motion sequential solution breaker current delay zero crossing

Abstract

The invention belongs to the power system field, concretely relating to a method for adjusting current delay zero crossing in a line protection motion sequential solution breaker connection / disconnection process. When carrying out an idle wire connection operation on a line which carries a parallel reactor and has a pre-existing singlephase earth fault, since current direct current bias is large, according to a line protection motion sequential which is generally employed, which means that after detecting a fault, a line breaker is controlled to carry out simultaneous brake disconnection of three phases by a line protection unit, a line breaker open operation fails possibly, and present main counter-measures can not thoroughly solve the above problem. According to the invention, reasonable adjustment is carried out on a line protection motion sequential. If the line has the pre-existing singlephase earth fault, when carrying out three-phase idle wire connection, after the fault is detected by the line protection unit, a fault phase line breaker is controlled to carry out single-phase brake disconnection first, after certain time, normal phase current direct current bias weaken to zero crossing of current, then a normal phase line breaker is controlled to carry out brake disconnection.

Description

technical field [0001] The invention belongs to the field of electric power systems, and in particular relates to a method for adjusting the line protection action sequence to solve the current delay zero crossing during the closing and opening process of a circuit breaker. Background technique [0002] According to the power system operation and test experience, when the line circuit breaker closes the line with high-voltage shunt reactor, the DC component of the circuit breaker current may be large, and the current may not exceed zero for a long time. The opening operation may cause the circuit breaker to be damaged because the current does not exceed zero for a long time and the arc cannot be extinguished. In practice, if the circuit breaker closes the empty line when there is a pre-voltage single-phase ground fault in the line, according to the protection action sequence commonly used at present, the line protection action orders the circuit breaker to open the three-pha...

AI Technical Summary

Problems solved by technology

However, when there is a pre-voltage single-phase ground fault on the three-phase transmission line, such as image 3 , there is also a certain dispersion in the relationship between the time when the sound phase current does not cross zero and the closing phase

Due to the existence of these two random factors, it is still possible for the circuit breaker to use the phase selection operation for the current to not exceed zero for a long time. The longest time for the circuit breaker to not exceed zero may exceed 0.6s, which is significantly longer than the normal arcing time of the circuit breaker (typically 20ms) )

[0019] On the other hand, in order to suppress the phenomenon that the current does not exceed zero for a long time, the phase selection operation circuit breaker is required to be closed near the voltage peak; and for the closing and empty line operation, closing near the voltage peak will lead to high overvoltage in the closing and empty line operation.

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