A multi-objective approach to PSS optimal tuning and placement for small-signal stability enhancement

This paper proposes a multi-objective methodology for the determination of optimal placement and tuning of power system stabilizers (PSS), two objectives are considered: the optimal location with a minimum number of PSS and maximum damping. The objectives are in conflict with each other in multi-objectives problems. Instead of a unique optimal solution, it exists a set of best tradeoffs between competing objectives, the so-called Pareto-optimal solutions. The main idea behind the paper, is to use a Nested Evolution Strategy (ES) to explore all the possible Pareto-optimal solutions in order to find the best compromise between performance (electromechanical oscillations damping) and cost (the number of PSS to be placed). The proposed algorithm is tested in the IEEE 68-bus system where the Pareto front has been successfully approximated by the Nested-ES.