Method for discriminating tail current in ineffective protection based on DC component blocking

Abstract

The invention discloses a method for discriminating ineffective protection tail current based on DC component blocking. The method uses proportion of DC component in a phase current to determine an ineffective tail current. The method is easy to operate, has high efficiency, greatly reduces the time of a replay protection apparatus in discriminating the ineffective tail current, and effectively increases accuracy in discriminating the ineffective tail current. The method makes it possible that when a fault current occurs, the ineffective protection does not refuse initiation, and when a CT tail current occurs, the ineffective protection is not wrongfully initiated, and the method accelerates phase-splitting and ineffective protection, prevents enlargement of an accident, and provides better safeguard for safe and stable operation of a power grid.

Description

technical field [0001] The invention relates to a method for judging the tailing of a failure protection current based on DC component blocking, and belongs to the field of relay protection of electric power systems. Background technique [0002] The relay protection device is an inseparable part of the power system, and it is the most basic, important and effective technical means to ensure the safety of power equipment and prevent and limit large-scale power outages in the power system. However, when a fault occurs in the system, the relay protection device issues a trip command, and the circuit breaker is disconnected to remove a fault, there is still an attenuating current on the secondary side of the electromagnetic current transformer, that is, CT (Current Transformer, current transformer) tailing Phenomenon. CT tailing current may cause the current criterion of circuit breaker failure protection to fail to return quickly, and the failure protection may malfunction af...

AI Technical Summary

Problems solved by technology

However, when a fault occurs in the system, the relay protection device issues a trip command, and the circuit breaker is disconnected to remove a fault, there is still an attenuating current on the secondary side of the electromagnetic current transformer, that is, CT (Current Transformer, current transformer) tailing Phenomenon

CT trailing current may cause the current criterion of circuit breaker failure protection to fail to return quickly, and the failure protection may malfunction after reaching the delay time, thereby expanding the fault range and causing serious consequences such as large-scale power outages

At present, there are not many methods for judging the current tailing of failure protection, and the criterion that the tailing current does not exceed zero is generally used. However, after the tailing current passes through the CT of the protection device, the phenomenon of current zero crossing may occur, and its applicability is not strong.

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