Coordinated parameters design of SEDC and GTSDC for SSR mitigation

In this paper, supplementary excitation damping control (SEDC) and generator terminal subsynchronous damping control (GTSDC) are designed in a coordinated way to solve the multimodal subsynchronous resonance (SSR) problem in series-compensated transmission systems. Firstly, the basic principle of the combined SEDC and GTSDC scheme for SSR mitigation is explained. Then the task of tuning control parameters of SEDC and GTSDC simultaneously is formulated into a constrained nonlinear optimization problem, in which different operating conditions/disturbances and equipment capacities are fully considered. Next the Genetic Algorithm and Simulated Annealing (GASA) are implemented to solve the problem and the optimal parameters are obtained. Finally, based on a practical system, Shangdu series-compensated system, the effectiveness of the coordinated controller is verified by both eigenvalue analysis and electromagnetic simulation. The results have demonstrated that the proposed method is effective and the optimized control parameters can greatly improve the damping of the three torsional modes.