Improvement of Voltage Stability in Power System by Using SVC and STATCOM

The increase in power demand has forced the power system to operate closer to its stability limit. Voltage instability and line overloading have become challenging problems due to the strengthening of power system by various means. The nature of voltage stability can be analysed by the production, transmission and consumption of reactive power. One of the major causes of voltage instability is the reactive power unbalancing which occurs in stressed condition of power system. Flexible AC transmission system (FACTS) devices play an important role in improving the performance of a power system, but these devices are very costly and hence need to be placed optimally in power system. FACTS device like static var compensator (SVC) and thyristor controlled series compensator (TCSC) can be employed to reduce the flows in heavily loaded lines, resulting in a low system loss and improved stability of network. In this paper, a method based on line stability index, real power performance index and reduction of total system VAR power losses has been proposed to decide the optimal location of TCSC. Now a day, Voltage Stability has become a major concern in power systems planning and operation. This problem has become very complex due to the continuous growing on system interconnections and demand for electricity and also due to economical and environmental constraints to properly expand the system. This has increased the importance of implementing suitable and efficient techniques for improving voltage stability of stressed power system. FACTS are one aspect of the power electronics revolution that is taking place in all areas of electric energy.