Virtual Inertia Emulation in islanded microgrids with energy storage system

Abstract

The inertial response plays a vital role in electrical networks to reduce the rate of change of frequency (RoCoF) following a contingency event. If the inertia has a low or zero value due to a lack of synchronous generators, then the electrical network might experience large undesirable frequency deviations. To overcome this problem, in previous research, mathematical methods have been emerged to enhance the system stability in current source based microgrids. The battery energy storage system embodies the isolated microgrid operates as voltage source and the implementation of the demand side management in which frequency is used as a communication signal. The requirement for inertia frequency response is indicated. In this work, the power electronics methods to emulate virtual inertia have been found, developed and compared. An overview of existing methods has been presented, which includes the introduction of the principles and comparison between their advantages and disadvantages. Based on those techniques, an additional PID controller has been recommended for the isolated microgrids working as current source. Furthermore, three control schemes to incite inertial responses have been developed for the microgrids in voltage source type as follows: 1) swing equation method, 2) low pass filter, and 3) an adjustable rate limiter. introducing swing equation, adding low-pass filter and setting rate limiter.