Mitigation of subsynchronous resonant oscillations via optimal control

This paper presents a novel approach leading to the formulation of the optimal control problem of subsynchronous resonance. The formulation allows the application of continuous state feedback laws as well as discrete control schemes. A unique solution technique is presented, based on an iterative gradient technique which computes optimal feedback gains and optimal parameters of discrete control laws. The methodology is applicable to large scale, non-linear, time varying, stiff systems. Because all problem constraints are explicitly incorporated the computed optimal controller design is always implementable. The methodology has been applied to design a specific decentralized control scheme for the subsynchronous resonant oscillations. Typical results with an actual power system are presented which illustrate the effectiveness of the solution.