Analysis of a Current Imbalance Accident in 220 kV Parallel Lines
摘要
The disconnector is one of the most widely used high-voltage switchgear in the substation. If it fails to close or refuse to operate, it will directly affect the safe, stable and reliable operation of the power grid, and may bring serious economic losses to society and enterprises. This paper analyzes a 220 kV parallel line current imbalance accident, checks the relevant intervals of substations on both sides of the fault line, and preliminarily analyzes the cause of the accident from three aspects: the characteristics of unbalanced current of the parallel lines and DC resistance. Finally, the equivalent circuit is built on the Matlab/Simulink simulation platform to verify that the root cause of the accident is the sudden increase of DC resistance caused by the inadequate closing of phase C disconnector on the bus side of line B. Moreover, the value range of sudden increase of DC resistance is given.