Soft open point-based service restoration coordinated with distributed generation in distribution networks

The soft open point (SOP) is an emerging power electronics device in place of normally open points/tie switches in distribution systems. During a fault, service restoration can be effectively achieved by coordinating SOPs and distributed generation units (DGs). In this paper, a novel two-stage SOP-based service restoration method in distribution networks is proposed: In Stage 1, a dynamic load-shedding scheme is prepared/applied during a fault occurred at the upstream grid, and the power supply to priority loads is maintained through DGs; in Stage 2, DGs, SOPs and switches are coordinated and operated to realize restoration in the outage area with controllable/dispatchable distributed generation units (CDGs) dispatched to their maximum capacity limits. In both stages, real and reactive power of SOPs is regulated to maximize load restoration. A mixed-integer nonlinear programming (MINLP) model through AC power flow is developed to formulate the restoration problem mathematically. The modified IEEE 33-node test system is used to validate the proposed restoration method combined with centralized or decentralized optimization. The proposed method is also compared with an existing method, showing much improved restoration performance.