Optimization Analysis of Overvoltage Protection Setting for Parallel Capacitor Banks

The parallel capacitor group in the substation is usually put into operation when the grid voltage drops, and is promptly disconnected when the grid voltage rises. If the disconnection is unsuccessful, there will be a delay in overvoltage protection disconnection. This article focuses on the accident of parallel capacitor banks in a 500kV substation. During the analysis of the causes, it was found that there were problems with overvoltage protection, which could not effectively protect the capacitor banks. Taking into account the effects of transformer impedance, harmonic current, and capacitor manufacturing tolerances, the reason for the high overvoltage protection setting was identified and verified through PSCAD simulation. Corresponding measures and suggestions were proposed for control strategy and overvoltage protection setting of parallel capacitor devices, providing reference for current design and operation personnel.