Optimal siting and sizing of SSSC using improved harmony search algorithm considering non-smooth cost functions

Static Synchronous Series Compensator (SSSC) is an elegant member of Flexible Alternating Current Transmission Systems (FACTS) devices. SSSC can be used to control the active and reactive power flows of transmission lines. In this paper, improved harmony search algorithm (IHS) is applied to determine the optimal location and parameter settings of SSSC in power systems. The optimal power flow (OPF) problem is solved with and without incorporating of SSSC in power systems considering the valve point loading effect and the prohibited operating zones of generation units. A simple model of SSSC based on power injection approach is implemented into OPF algorithm. The main advantage of the simplified model is avoiding any modifications in the original structure of Jacobian matrix. Consequently, the complexities of OPF algorithm are reduced. In addition, the resistance of SSSC is considered in this model. The OPF solution with the simplified SSSC model using IHS optimization technique are validated based on the standard IEEE 30-bus test system. The comparative study with conventional harmony search (HS) and other techniques demonstrates the superiority of the developed OPF solution using IHS algorithm.