International Journal of Research and Innovation in Applied Science (IJRIAS) | Volume IV, Issue X, October 2020 | ISSN 2454–6186

A Review of Control and Stability of Microgrid during Transitions

Bangar Raju. L, Subba Rao. K
Electrical and Electronics Department, Koneru Lakshmaiah Educational Foundation (Deemed to be University),  Guntur-522502, A.P., India

Abstract: The technological developments on Renewable Energy Sources have lead to research in control methods to make them useful electricity generators for feeding the loads in Microgrids and Utility grids. The Microgrid with all its Distributed Generators, Battery Energy Storage Systems and Loads has to be stable to supply power to the connected loads, maintaining frequency, voltage at Point of Common Coupling and sharing the load proportional to their capacities. The Microgrid with all its Distributed Energy Resources, which include distributed generators, battery systems and loads along with utility grid connection, constitute a mini power system network. This network has got different states, islanding, transition from grid to island and resynchronization to grid. The two transition states in which Microgrid has to be controlled and make it stable are, grid to island and synchronization back to grid. The different methods based on control techniques of synchronizing controller which monitor voltage, phase and frequency of Microgrid and main grid on either side of Static Switch and brings stability in the system. In this paper these two have been discussed elaborately, which gives fairly a good idea about control and stability of Microgrid.
Keywords: RES- Renewable Energy Sources; DER- Distributed Energy Resources; DG- Distributed Generators; DOE- Department Of Energ; BES-Battery Energy Storage systems; PCC-Point of Common Coupling; NDZ-Non-Detection Zone; CERTS- Consortium of Electric Reliability Technology Solutions; PLL-Phase Locked Loop; SRF-PLL- Synchronous Reference Frame-PLL

I. INTRODUCTION

The Microgrid as per DOE, is a cluster of DGs, BESs and loads connected within a clearly defined electrical boundaries, which acts as a single controllable entity with respect to grid. The Microgrid can connect and disconnect from main grid to operate in grid or islanded mode. The general condition of Microgrid is in connection with utility grid. The Microgrid is connected to the PCC through parallel interfacing inverters and to the main grid via static switch as shown in Fig.1. In the event of fault on the main grid, the Microgrid has to be islanded seamlessly with the aid of any of the islanding detection methods and operate autonomously in island[1], [2]. There are basically intentional and un-intentional islanding modes.. Intentional are meant to isolate Microgrid for any maintenance work either on Microgrid.

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