Fuzzy harmony search algorithm based optimal power flow for power system security enhancement

•FHSA is proposed to minimize the total fuel cost and severity index.•Line overloads are removed by minimizing severity index.•Pitch adjustment rate and bandwidth are updated through fuzzy logic system.•Effectiveness of the proposed algorithm is tested on IEEE 30, 57 & 118 bus systems. This paper proposes the integration of fuzzy logic system with harmony search algorithm (FHSA) to find the optimal solution for optimal power flow (OPF) problem in a power system. The objective of the method is to minimize the total fuel cost of thermal generating units having quadratic cost characteristics and severity index (SI). The generator active power, generator bus voltage magnitude, transformer taps, VAR of shunts and the reactance of thyristor controlled series capacitor (TCSC) are taken as the control variables. The adjustment of proposed algorithm parameters such as pitch adjustment rate (PAR) and bandwidth (BW) is done through fuzzy logic system (FLS). The effectiveness of the proposed method has been tested on the standard IEEE 30 bus, IEEE 57 bus and IEEE 118 bus systems in MATLAB environment and their results are compared with conventional harmony search algorithm (HSA) and other heuristic methods reported in the literature recently.