Design of a Wide-Area Damping Controller Considering Communication Time Delays

Increasing introduction of PVs and expanding operation areas, inter-area low frequency oscillations become a serious problem and are often caused from poor system damping. According to rapid development of wide-area measurement systems (WAMS), wide-area damping controllers (WADC) designed using wide-area signals obtained from WAMS have been proposed to enhance damping of inter-area low frequency oscillations. As wide-area signals are remote signals, they need to be transmitted through a communication network. Communication time delays caused by transmission of remote signals are one of the key factors influencing system stability and damping performance of WADCs. In this paper, we propose a WADC accommodating a state feedback controller. The proposed WADC's feedback gain K is updated for each time communication delay that occurs in the wide-area signals sent by the PMU. Therefore, the eigenvalues of delay using the Padé approximation method are given desirable eigenvalues using the pole placement method to compensate for communication delays. To evaluate system stability and damping performance of the proposed WADC, we perform transient analysis with three-phase faults using the IEEJ EAST 30-machine System Model. We verify the effectiveness of the proposed WADC through simulation studies with different time delays. Simulations showed that the proposed WADC could achieve a damping performance similar to the damping performance when there are no communication time delays, even if communication delays occur in wide-area signals.