Objectives, Requirements and Implementation of a Service Restoration Algorithm for AC-DC Distribution Grids

With the increasing penetration of DC based devices and the improving performance of power electronics converters, more and more advantages foster the deployment of hybrid AC-DC distribution grids. Although the operating control of AC-DC grids is consistently studied in the literature, several protection aspects need further analysis. This paper focuses on the reliability of AC-DC distribution grids, proposing a Service Restoration (SR) algorithm to efficiently re-energize the disconnected nodes in case of electrical faults. To determine the SR solution, the algorithm inspects multiple criteria together: the number of reconnected nodes, the minimization of power losses, the presence of telecontrolled switches, the criticality of the nodes facilities and the restoration feasibility according to power forecasts. The evaluation of reconfiguration topologies is based on the operational limits of AC-DC converters and energy sources; additionally, the power transfer is controlled by setting as optimization objective the losses minimization. The conducted tests, considering different load and generation configurations, prove the applicability of the proposed algorithm in evaluating the feasibility of reconfiguration topologies and computing the near-optimal SR solution.