Load Shedding and Restoration for Intentional Island with Renewable Distributed Generation

Abstract

Due to the high penetration of renewable distributed generation (RDG), many issues have become conspicuous during the intentional island operation such as the power mismatch of load shedding during the transition process and the power imbalance during the restoration process. In this paper, a phase measurement unit (PMU) based online load shedding strategy and a conservation voltage reduction (CVR) based multi-period restoration strategy are proposed for the intentional island with RDG. The proposed load shedding strategy, which is driven by the blackout event, consists of the load shedding optimization and correction table. Before the occurrence of the large-scale blackout, the load shedding optimization is solved periodically to obtain the optimal load shedding plan, which meets the dynamic and steady constraints. When the blackout occurs, the correction table updated in real time based on the PMU data is used to modify the load shedding plan to eliminate the power mismatch caused by the fluctuation of RDG. After the system transits to the intentional island seamlessly, multi-period restoration plans are generated to optimize the restoration performance while maintaining power balance until the main grid is repaired. Besides, CVR technology is implemented to restore more loads by regulating load demand. The proposed load shedding optimization and restoration optimization are linearized to mixed-integer quadratic constraint programming (MIQCP) models. The effectiveness of the proposed strategies is verified with the modified IEEE 33-node system on the real-time digital simulation (RTDS) platform.