Excitation System Failure Analysis of Fast Dynamic Response Synchronous Condenser

The new generation large-capacity synchronous condensers have been successfully applied to the UHV DC converter stations and the hub substations to provide dynamic reactive power support for the system. Excitation system failures are mostly caused by the malfunctions or faults of the thyristor, the fast fuse, or the pulse circuit. This article is based on a typical short-circuit fault of the excitation system rectifier circuit in the synchronous condenser. According to the experimental analysis and simulation, it is found that this type of faults is caused by the internal interference of the thyristor pulse cable. When the thyristor is blocked in the reverse direction, the thyristor receives a reverse voltage and interference trigger pulse, which causes the leakage current increase. The long-time increase of the loss of the thyristor causes the thyristor breakdown due to the thermal failure. Through this type of excitation system short-circuit fault research, it is recommended that the manufacturer modify the pulse cable wiring method by separating the GK pulse lines to prevent the failures of the three-phase thyristors from being damaged at the same time The standardized design of the excitation system should be modified to avoid the expansion of the faults, ensuring the personal safety of theoperation and maintenance personnel and the safe and stable operation of the synchronous condenser. © 2021, Power System Technology Press. All right reserved.