A Framework for Load Service Restoration Using Dynamic Change in Boundaries of Advanced Microgrids With Synchronous-Machine DGs

Abstract

In this paper, a new strategy for service restoration of de-energized loads is proposed using advanced technologies of microgrids (MGs) that accommodate distributed energy resources (DERs). In particular, backup distributed generators (DGs), initially used for critical loads within a building, have recently been operated under normal grid conditions while exporting excess power to other loads on the same or different feeders. In addition, smart switches (SSWs) have been installed in a distribution grid to reduce the frequency and duration of power outages. Using flexible communication links, the sensors of the SSWs exchange control and measurement signals with grid management systems, namely, an advanced distribution management system, an MG energy management system, and a DER management system. This paper focuses on developing a methodological framework to determine the operating modes of synchronous-machine DGs and the on–off operation of SSWs, so as to change dynamically the boundaries of MGs that are formed in a distribution grid for fault isolation and load restoration. Simulation case studies demonstrate that the proposed strategy is effective in mitigating the influence of a network fault and restoring de-energized loads while successfully maintaining frequency and voltage levels in MGs.