Application of Lyapunov stability criterion to determine the control strategy of a STATCOM

While the primary purpose of a STATCOM is to support busbar voltage by injecting appropriate reactive power, it can also improve the dynamic behaviour of a power system. The paper proposes a control strategy of a STATCOM to improve the stability of a power system which is derived from the stability criterion of Lyapunov´s second or direct method. The proposed control strategy of the STATCOM was then tested on a single-machine infinitebusbar system and the IEEE 20-machine test system. It was found that the proposed control strategy of a STATCOM could significantly enlarge the stability region and, hence, stability of a power system. The effect of STATCOM rating on system stability is also investigated.