Adaptive group search optimization algorithm for multi-objective optimal power flow problem.

•A new method for solving the multi-objective optimal power flow problem is proposed.•Total operation cost, total emitted emission, and proposed N-1 contingency index are considered as objectives.•A new security index is proposed.•The fuzzy decision-making approach is utilized to handle the multi-objective OPF problem.•AGSO is proposed to precise the convergence characteristic of conventional GSO algorithm.