Universal and Seamless Control of Distributed Resources-Energy Storage for All Operational Scenarios of Microgrids

Abstract

This paper proposes one control paradigm that can operate in both grid-connected and islanded modes, hence does not need any sort of an islanding detection method. The proposed method automatically and seamlessly rides through a fault on the grid side, and controls the microgrid's voltage and frequency during islanded operation. During an islanded operation, it utilizes the combination of distributed generation-energy storage similar to the prime mover of a synchronous generator to control the frequency. A comprehensive active and reactive power control is proposed that minimizes the usage of a local fossil-fuelled auxiliary generator. The method is based on expanding the so-called non-detection zone to all operational scenarios including islanded mode, hence having small “undetectable” voltage and frequency deviation. As soon as the grid is reconnected, the distributed generator is automatically and seamlessly synchronized with the grid. This is achieved through keeping phase-locked loop as a part of the operation in islanded mode without altering its phase angle. The proposed method is validated using PSCAD/ EMTDC simulation.