The Impact of Model for MOV-Protected Series Capacitors on System Stability and Available Transmission Capability

Series capacitors compensation plays a more and more important role in long-distance and large-capacity transmission system, whose model has a significant impact to system stability study. Firstly, both gap protected SC model and linearized model is applied into the available power transmission capability and system stability study in electromechanical transient simulation in this paper. Secondly, it is showed that huge short-circuit current might be caused by using gap protected SC model, and the result of transmission capability and system stability study may deviate in that point. Finally, the comparison between the simulation and theoretical analysis shows that the adoption of linearized model could bring an acceptable result which is close to the electromagnetic transient physical characteristics of SC. The linearized model for MOV-Protected SC is proved to be accurate and effective in a real 500kV SC project, and is recommended in system stability study of SC, and fault current limiter.