Modeling and Analysis of Standalone Inverter-Based Microgrid with Grid-Supporting Voltage-Source Control under Changing Load

摘要

With the increasing penetration of renewable energy sources in electricity networks, the concept of microgrids has been developed to harness these sources and effectively integrate into the grid. The autonomous operation of a microgrid is quite challenging, considering the fact the interfacing inverters are expected to regulate the islanded system's voltage and frequency. Providentially a grid forming control of the interfacing power electronic inverters has proven to help regulate the frequency and voltage. However, with the dynamic nature of typical electrical loads, it is imperative to develop a robust control system that dynamically adjusts to the changing grid load condition. Consequently, a grid supporting control for the inverter-based microgrid can play a more active role in frequency and voltage regulation under dynamic loading conditions. In this work, a grid supporting control, which makes the inverter-based microgrid to operate as a voltage source, is proposed and analyzed under a changing load. The grid supporting scheme implements droop and virtual output impedance control, which dynamically modify their operating parameter according to microgrid conditions. The performance of this control is evaluated based on its ability to improve the voltage and frequency control in autonomous mode.