Frequency Regulation in Isolated Microgrids Through Optimal Droop Gain and Voltage Control

This article presents an adaptive active power droop controller and voltage setpoint control in isolated microgrids for optimal frequency response and stability after disturbances. The control scheme involves an optimal and model predictive control approach that continuously adjusts the active power droop gains and the voltage setpoints of Distributed Energy Resources (DERs) to maintain the frequency of the system within acceptable limits and enhance the primary frequency response of the system, while taking into account the active power sensitivity of the microgrid loads to the system's operating voltage. The proposed control scheme is tested, validated, and compared with previously proposed techniques using time-domain simulations for a test system based on a CIGRE medium voltage benchmark microgrid under different realistic conditions, demonstrating the advantages of the proposed approach.

I. Introduction

Recently, there has been a large-scale deployment of Distributed Energy Resources (DERs) to address both economic and environmental issues associated with conventional power plants located primarily at the transmission level. As a result, Renewable Energy Sources (RESs) are being deployed at both transmission and distribution systems. These intermittent DERs are affecting the characteristics of the grid due to the power electronics used to connect these systems, which can place a significant burden on power systems, since these were not designed to handle such DERs [1].