Application of Gravitational Search Algorithm to Improve Power System Security by Optimal Placement of FACTS Devices

In deregulated power industry, system parameters such as bus voltages and line power flows are operated near the limit values to meet the demanded load. However, this is a very dangerous situation for the secure operation of power systems. In order to preserve the power system security, it is necessary to use compensating devices for altering the line power flows and bus voltage regulation. In this matter, FACTS devices are the best compensating devices employed so far, for efficient performance of the power flows. On the contrary, poor location of FACTS devices can cause unnecessary power flows and disturb the bus profile which lead to security issues. In the paper, bus voltage deviation and line power flow factor to the maximum limit are considered as security indexes. These indexes are used as objectives for security problem and are compensated by optimally placing the FACTS devices. Here, the FACTS devices used are Thyristor Controlled Series Compensator (TCSC), Static VAR Compensator (SVC) and Unified power flow controller (UPFC). These FACTS devices are needed to be placed optimally in the power system to improve the security margins. The proposed algorithm for this purpose is Gravitational Search Algorithm (GSA). Additionally, installation costs of FACTS devices and power system losses are also included in the objective function for economic operation of FACTS installations. The proposed GSA method is validated on IEEE 30, IEEE 57 bus test systems for optimal allocation of FACTS devices. The performance of the proposed GSA is analyzed and compared with existing techniques.