Transient Stability Improvement by Using Advanced Static VAR Compensators

Advanced static VAR compensators (ASVCs) are used to improve the transient stability of electric power systems. In this paper we present a new control strategy, which has superior performances compared to the conventional control techniques for these systems. The proposed method utilizes a novel current reference based on the transient energy function (TEF) approach. It also includes the voltage limits in the optimizing process using the Lyapunov theory and linear programming. In addition, it is optimized considering the permissible system conditions. A continuous control of the reactive power flow is also achieved. The proposed ASVC is modeled in single-machine and multimachine systems. In order to verify the excellent performances of the proposed approach compared to the conventional control techniques and systems without ASVC, simulation results in response to severe disturbances in a single-machine system as well as a three-machine system are provided.