A review of AC microgrid control methods

The concept of microgrid (MG) has been introduced as a solution to future electrical grid challenges such as the rapid increase of electrical demand, harvesting energy from renewable energy sources, and ensuring the quality and reliability of electricity supply. Distributed energy sources, as well as energy storage systems are interfaced with MGs through power electronic inverters. Control systems of the power electronic inverters in MGs play a key role in ensuring the perfect performance of MGs. This paper presents a comprehensive review of various control systems used in MGs. In particular, different levels of MG control systems have been investigated and corresponding control strategies at each level have been compared in detail. This paper categorizes MG control systems into four levels: 1- The converter output control that shapes the output current in order to control the flow of output power, 2- The power sharing algorithm that guarantees the even distribution of the load between parallel inverters, 3- The MG supervisory controller (secondary level) that deals with the supervisory control of the converters within the MG, and 4- The grid supervisory controller (tertiary level) that controls the flow of power between the main grid and the MG.