Control strategy of on-load tap-changer based on digital substation

Abstract

Voltage stability is one of the aspects of the power system stability. Since regulating transformers are more and more used in modern power system, tap change has often been considered as a principal mechanism that may lead to voltage collapse, but tap change can also rescue a would-be collapse system by extending the power transfer limit. Using time domain medium-and-long term voltage stability simulation program, the influence of the action of on-load tap-changer (OLTC) on voltage stability is analyzed. The development of its high-speed communication network in real-time system and the implementation of the IEC61850 standard have made the construction of digital substations possible. Based on digital substation system, the strategies of OLTC control is given which can improve the power system stability.