The aim of this article is to solve a problem of choosing an optimal PST phase-shifting angle at the 500 kV Ulke substation by means of multiobjective optimization methods. The power system state control and dispatching is not a trivial process, when a dispatcher has to assess the current state and take decisions to improve its indicators. The main problem is a big number of possible states. Each state is characterized by a set of different indicators, reflecting reliability, quality and economic efficiency. Traditional methods of multiobjective problem solving, using adduction of a vector criterion to a scalar one (main criterion method, linear contraction method and others), are subjective and demand great experience from a power system dispatcher. In this article the phase-shifting transformer work at the 500 kV Ulke substation is simulated on the basis of UES Russia and Kazakhstan models. The Pareto set of power system states for three vector criteria is obtained by the direct search. The power system state analysis is fulfilled by means of Pareto front, from which an optimal PST settings range could be recommended.