Stabilisation of wide-area supplementary damping controller of TCSC via an improved integral inequality approach

摘要

Wide-area signals are used as a feedback input to the supplementary damping control of FACTS devices to increase the damping ratio of low-frequency inter-area mode in power system. However, using a communication network to transfer these signals from the PMUs to the control centre causes a network-induced delay in the feedback loop. Under acute conditions, a time delay can decrease the performance of the designed controller and even cause system instability. In this paper, a wide-area supplementary damping controller of TCSC is designed to dampen inter-area oscillations and compensate for the time delay. As a first step, we model a power system with network-induced delays as a typical time-delayed power system and selected wide-area feedback signals using modal analysis. Secondly, a wide-area supplementary damping controller is designed. For WASDC implementation, network-induced delays are dealt with using a delay-dependent approach. A delay-dependent method combined with a suitable Lyapunov-Krasovskii functional is used to determine the stability and stabilisation conditions that guarantee the asymptotic stability of the power system subjected to network-induced delays. Using an improved integral inequality, less conservative conditions are obtained. The performance of the proposed controller is evaluated using two-area four-machine power system benchmark model.