Modified PSO-Based Virtual Inertia Controller for Optimal Frequency Regulation of Micro-Grid.

Abstract

Owing to the growing need to address the energy crisis by the traditional sources (e.g. Thermal power plants), as well as the associated environmental concerns posed, the power system witnessed increased penetration of power electronics-based power sources like solar, wind, and energy storage in terms of battery technologies. Consequently, modern compared with traditional power systems have become more susceptible to large frequency fluctuations due to the emergence of stability issues. Prominent among these include the reduction of system properties such as damping and inertia which are significant characteristics of system stability. Insufficient inertia drives the grid frequency outside the acceptable range under severe disturbances and this may lead to an outage of generators and tripping, unscheduled shedding of load, system collapse, and in the severe scenario, an entire power blackout, this threatens the system dynamic security. To preserve the system's dynamic security, this paper proposes an alternative approach to frequency regulation built upon a PID-based Virtual Inertia Control (VIC) which imitates the inertia property. The proposed virtual inertia uses the frequency derivative to emulate virtual inertia. The optimality search capability of the Particle Swarm Optimization (PSO) technique is used to design the proposed controller. Evaluation of the robustness of the proposed controller is demonstrated through Time Domain Analysis, considering different system operating ranges for improving frequency stability and resilience. Improved performance of the proposed controller when paralleled with the traditional virtual inertia controller shows a 69.2% reduction in frequency nadir under the condition of reduced system inertia, 70% without RESs integration. Also, 50.7% and 44.4% improvement in the reduction of frequency nadir and maximum overshoot respectively were observed under the situation of nominal system inertia, 100%, and Renewable Energy Systems(RESs) penetration.