Investigation of Disruptive Effect on Voltage Stability Caused by Line Contingency in Power Systems and Improvement of System Stability

Abstract

There are many situations that cause voltage instability in power systems. One of these situations is line contingency that may occur in power systems. In this study, the effects of line contingency on the steady state are investigated in the IEEE 9 buses power system. Firstly, the static and dynamic analyses of the power system are made in normal operating condition. Continuous power flow analysis was used as static analysis and time domain simulation method were used as dynamic analysis. Then each transmission line is deactivated and the analyses are repeated. The changes in the maximum loading capacity and voltage stability of the system are investigated in case of each transmission line contingency. Finally, Static Var Compensator (SVC) is connected to the power system to improve the stability level. When the SVC is connected to the power system, the maximum loading capacity of the system is examined and the effects of this situation on the voltage stability are analyzed. All analyses are performed in the MATLAB® PSAT (Power System Analysis Toolbox). The results showed that the line contingency reduces the maximum loading capacity and deteriorates the voltage stability. It has been observed that both the problems can be eliminated with the SVC integration into the power system.