The impact of time delay on robust control design in power systems

A centralized wide area controller design using systemwide data is proposed to enhance the dynamic performance of a large power system. The time delay exists in the data communication for this controller. Long time delay may be a detriment to wide area control system stability and delay may degrade system robustness. This paper analyzes the impact of time delay on robust wide area controller design in power systems. Time delay is described using the Pade approximation and is simulated within the robust wide area control system. According to numerous simulations, it is found that the overshoot value of active power variation increases and the settling time is lengthened when time delay occurs. The closed-loop control system may become unstable when the time delay is over a certain value. A robust controller can be redesigned to accommodate the possible long time delay. The impact of time delay on robust controller design is studied using a two-area four-machine system.