Optimal placement and sizing of SVC for loss minimization and voltage security improvement using differential evolution algorithm

The emerging trend of restructuring power systems, security is becoming a major concern for electric utilities. The security assessment of power system is being considered as an important problem in planning, operation and control. Security assessment entails that the system should remain in secure operating state under abnormal conditions. In a power system the Security assessment is carried out by using the voltage performance index (VPI) following a contingency. Contingencies are termed as the uncertain events, occurred due to line outage in the system. VPI can be used for identifying the critical contingency from the perspective of bus voltage violation limits. Flexible Alternating Current Transmission Systems (FACTS) devices are having a great impact on the performance of the transmission network. FACTS devices are used for controlling real and reactive power flows and regulating the bus voltages in power systems. Also, FACTS devices raises power transfer capability reduces system losses and improves system stability, because of their fast and flexible control characteristics. Owing to their huge capital cost, it is essential to place these devices optimally in a power system. In this paper, Differential Evolution (DE), a population based stochastic meta-heuristic optimization algorithm is applied for optimal placement of static var compensator (SVC) aimed to the voltage security enhancement of a power system. The SVC placement is considered to be a planning problem and is formulated as a multi-criteria problem comprising of minimization of real power loss, voltage security and investment cost of SVC under single line outage contingencies. Effectiveness of the DE algorithm based approach has been demonstrated on IEEE 30-bus test system.