Voltage-sag-severity-index based size planning of shunt capacitor banks to improve short-term voltage stability

Short-term voltage stability problem (STVSP) is a serious threat to receiving-end power systems which are short of reactive power reserves. This paper discusses how to plan the size of shunt capacitor banks (SCB) in a receiving-end power system to achieve a maximum voltage stability margin. The local generators and SCB are two important reactive power resources in receiving-end power systems. The size of SCB affects the reactive power output of generators in steady state. Furthermore, it impacts the voltage stability margin. It is necessary to obtain the best size of SCB, because an over-design or an under-design is not capable to eliminate the STVSP. We propose a voltage sag severity index to determine the size of SCB in this work. The proposed method has been tested on a typical receiving-end power system to work out the best size of SCB and then to verify its effectiveness through time-domain simulation.