Hierarchical control of inverter-based microgrid with droop approach and proportional-integral controller

Abstract

By increasing the penetration of renewable resources in power systems, which are mostly inverter-based, voltage and frequency control has faced many challenges. Unlike the synchronous generators in large power systems, these sources have no resistance against load changes due to their low inertia, therefore, controlling the voltage and frequency of inverter-based microgrids requires new approaches. In this article, by taking feedback from the output voltage and current of the inverter and using the Proportional Integral controller, the desired control signal to be applied to the inverter is obtained in a way that initially creates a phase and voltage difference between the DGs in the microgrid, the power flow is established in a way that without the need for any communication link, the balance of energy production and consumption is established in an island mode, and at the end, the voltage and frequency of Distributed Generations are restored to their nominal values. The presented control logic is also implemented in Simulink MATLAB software and its results are measured and evaluated.