2018/05/03 by Jonas Kristiansen Nøland, Fredrik Evestedt, Urban Lundin · 11 citations
Engineering · #HVDC Systems and Fault Protection #Power Systems Fault Detection #Power System Optimization and Stability #Exciter #Thyristor #Fault (geology) #Overvoltage #Engineering #Circuit breaker #Voltage #Computer science #Control theory (sociology) #Electrical engineering
paper · doi:10.1109/tie.2018.2833044
published in IEEE Transactions on Industrial Electronics 66(2), 842-851 (Institute of Electrical and Electronics Engineers)
openalex publication_date 2018/05/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
The excitation system plays a critical role in the operation of synchronous generators. An equipment failure could impact the voltage quality for smaller grids. Furthermore, it can lead to cost penalties and reduced production for the power plant owner. Recently, a new high-speed-response rotating brushless exciter was developed that employs remote control of the rotating thyristors on the generator shaft. This has led to new possibilities for improving the performance of brushless exciters. This contribution investigates the failure modes of a dual-star outer pole exciter that feeds two separate thyristor bridges connected in parallel during a normal operation. The possibility of a redundant postfault operation due to open-thyristor or open-phase faults is demonstrated using experimental testing. The system is compared with the fault performance of a conventional three-phase system. This paper includes the implementation and validation of a fault-predicting double d-q exciter model. In addition, the dangerous effects of a shorted-thyristor fault are investigated. A “skip firing” protection technique is briefly demonstrated for the fast isolation of such faults, yielding nondestructive postfault recovery and redundant failure-mode operation. The evidence shows that the dual-star exciter is a competitive choice for the future development of fault-tolerant brushless exciters.