Voltage Stability in Power System - A Survey

Reactive power optimization (RPO) is an important issue for providing the secure and economic run of the power systems. The importance of reactive power planning on economic profit and secure running has been increasing, because of the increasing fuel costs and investment funds. It is also quite important for an electric operator to provide voltage in a specified range for the customers. As such, RPO provides voltage control in power systems. Furthermore, it is used for decreasing active power loss and making better power flow by enhancing the voltage stability. The voltage stability index is used to find optimal location of the facts devices in the network. Voltage stability problems usually occur in heavily loaded systems. Nowadays the power demand increases enormously, hence in a large interconnected power system network subject stress condition. This situation can be handled by increasing the generation or reduce transmission losses. Through various uses of FACTS devices in transmission lines, the voltage stability profiles is maintained and by use of algorithms like PSO, GA, SFLA the voltage stability and the profile of the system has been improved in transmission lines.