MILP-Based Service Restoration Method Utilizing Both Existing Infrastructure and DERs in Active Distribution Networks

This study proposes a service restoration method that utilizes the distributed energy resources (DERs) as the control measures as well as the existing infrastructure of the distribution system. The existing infrastructure includes switching operations, load shedding, and tap operations of the on-load tap changers (OLTCs). In addition, the DERs include reactive power control of the distributed generation (DG), charge/discharge of the energy storage system (ESS), and intentional islanding operation using the black-start function of the ESS. For this purpose, the following model is applied to the optimization problem based on mixed-integer linear programming. First, a linear constraint considering the voltage drop due to the impedance of the main transformer is used for practical application of an OLTC. Next, a linear constraint is formulated for grid code-based DG reactive power control. In addition, constraints for the ESS are defined. Here, the radiality constraints are formulated to distinguish the grid-connected and islanding operation modes based on the location and state of the ESS. Finally, simulations of the application of the control measures conducted on a 150-node test system, designed based on the data of the actual system in Korea, are conducted and the results are analyzed to verify the proposed method.