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.

Summary In recent times, renewable energy sources (RESs) have been potential alternatives over the conventional generation systems connected to the grid. The power electronic inverters are the principal media of interface for connecting the RESs to the utility grid system. This work is primarily focused on the comparative analysis of Droop, virtual synchronous machine (VSM), and virtual oscillator control (VOC) techniques for the parallel operated inverters in a standalone Microgrid (MG). Droop control emulates only the droop characteristics of synchronous machines such that the transient response of this controller is not significant. VSM imitates not only the droop characteristics of synchronous machines but also the swing equation. Therefore, VSM has a remarkable difference in the dynamic performance of the system. In droop and VSM, the feedback signals such as voltage and current are measured to calculate the averaged real and reactive powers. However, the VOC works on instantaneous feedback signals such that it achieves much faster synchronization and good power‐sharing. The philosophy of the proposed VOC is to control an inverter such that it emulates the behavior of a nonlinear dead‐zone oscillator. The performance analysis of the system with the aforementioned controllers has been studied based on MATLAB/Simulink and Opal‐RT digital simulation. From the comparative analysis, it is observed that the VOC gives a better performance compared to droop and VSM control. The experimental results show the efficacy of the proposed VOC control method.

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