Frequency regulation by optimized fuzzy based self-adaptive virtual inertia control for microgrid with variable renewable penetration

Abstract

The increasing use of renewable energy sources are solving environmental issues, energy shortage problems and result in economic growth. Microgrid can provide a framework for connecting RESs to the utility grid, but high penetration of RESs make it difficult to lower the Rate of Change of Frequency (RoCoF). In this research, a self-adaptive Virtual Inertia Control (VIC) technique is proposed to tackle this instability issue. VIC method simulates virtual inertia, enhancing inertia of the overall system and frequency stability. VIC technique links energy storage systems to the utility and helps with power supply. However, an accurate analysis is necessary to regulate the Virtual Inertia (VI) constant value, which could adequately eradicate the adjustment mistakes & system instability. Fuzzy logic controllers can tackle non-linear problems and provide robustness, and reliability. This research presents a fuzzy based self-adaptive VIC system for stable load frequency regulation in low-inertia microgrid. In addition to this, a fuzzy based secondary frequency control is also proposed in this study. A fuzzy based self-adaptive VIC is developed for VI constant emulation using real power fluctuations of RESs and frequency regulations. The Arithmetic optimization algorithm technique is used to obtain the optimized controller parameters. Efficacy of the proposed self-adaptive VIC with fuzzy based secondary thermal controller is validated against no VIC with integral and fuzzy based secondary frequency controller, standard VIC with integral as well as fuzzy based secondary frequency controller and self-adaptive VIC with integral secondary controller for high/low renewable sources penetrations and system parameter variations. Finally, real time validation of the proposed VIC approach has conducted with the help of OPAL-RT 5700 and the experimental results are compared with conventional VIC method.