Sequential Distribution System Restoration With Inverter-Based Distributed Generations Considering Dynamic Frequency Constraints

When extreme events cause large-scale outages, local power sources, such as distributed generations (DGs), can be coordinated to restore critical loads in distribution systems (DSs). However, the inertia of an isolated system formed by inverter-based DGs is relatively low, so the dynamic frequency during the restoration is essential as it may trigger the protection and cause restoration failure. Therefore, the dynamic frequency constraints should be considered when making decisions on the restorative actions. This paper proposes a dynamic frequency constrained service restoration method for the DS. First, according to the frequency response of inverter-based DGs, the analytical formulation of the system frequency nadir is derived and piecewise linearized. By incorporating the linear frequency constraints, a mixed-integer linear program is proposed for the restoration problem, by solving which the optimal restorative sequence and system operation state after each restorative action can be determined. Finally, the effectiveness of the proposed method is verified by a modified IEEE 13-node test feeder.