Parallel inverter control using different conventional control methods and an improved virtual oscillator control method in a standalone microgrid

Abstract

Partly because of advances in power electronic converters, the share of renewable energy in power generation is steadily increasing. The main medium of interface for integrating renewable energy sources to the utility grid is the power electronic inverter. Virtual oscillator control (VOC) is a time-domain approach for controlling parallel inverters in a standalone microgrid (MG). The concept is to simulate nonlinear deadzone oscillator dynamics in a system of inverters to ensure a stable AC MG in the absence of communication. VOC is a time-domain and self-synchronizing controller that simply requires the measurement of filter current, whereas traditional droop control and the virtual synchronous machine (VSM) require low pass filters for active and reactive power calculations. In this work, a particle swarm optimization (PSO)-based VOC method (VOC-PSO) is proposed, in which the parameters of the VOC are designed using the PSO algorithm. The system performance using droop, VSM, VOC, and VOC-PSO controllers are investigated using MATLAB and Opal-RT real-time digital simulator platforms. The results show that the proposed VOC-PSO gives improved performance over other control strategies. The efficacy of the proposed VOC-PSO control method is also demonstrated by the experimental results.