Investigation of induction motor support in weak microgrids using virtual synchronous generator

Microgrids having inverter based distributed generators (DGs) are becoming popular with increase in demand for clean and sustainable energy sources such as solar, wind etc. In islanded microgrids, decentralized parallel operation of these inverters is achieved using frequency and voltage droop control technique. Such inverters are known as synchronverters or virtual synchronous generators (VSG). These VSGs have small overload capability. Hence, in an islanded microgrid consisting such VSGs, it is important to investigate the performance of the system during starting of an induction machine of appropriate rating. This paper investigates the performance of various VSG models for the DoL starting of an induction motor in a multi-inverter microgrid. The comparison is done on the basis of voltage sag/dip in the microgrid at the instant of motor starting and the power sharing during the transient period. The investigation is verified through simulations using MATLAB Simulink and experimentally using a 3 DG scaled micro-grid laboratory set up, in which the induction motor is implemented through real-time power level emulation.