Frequency Regulation Strategy in Islanded Microgrid With High Renewable Penetration Supported by Virtual Inertia

The widespread adoption of power converter-based renewable energy sources (RESs) has led to a significant decline in overall system inertia within interconnected power systems. This reduction in inertia poses a significant challenge, as it increases the susceptibility of the interconnected power system to instability. To address this critical issue, this research proposes an application of virtual inertia control as a means to enhance the frequency stability of interconnected power systems characterized by a high penetration level of RESs. The proposed approach leverages a derivative control technique to enable higher-level virtual inertia emulation. By introducing a second-order characteristic into the virtual inertia control loop, the method emulates inertia, resulting in improved frequency stability and enhanced system resiliency. A dynamic model of microgrid linked is developed and the frequency stability is ensured by a Fractional Order Proportional Integral Derivative (FOPID) controller using Teaching Learning Based Optimisation (TLBO) algorithm. The problem is formulated with Integral Time Squared Error (ITSE) of frequency deviation for determining the controller. The performance of the developed controller is compared against conventional controllers in terms of the stability of the microgrid. In addition, the superiority of TLBO is analysed by comparing it with other well-established algorithms in the literature. The suitability is established under various scenarios of load and renewable uncertainties. Furthermore, the work also includes sensitivity verification of the controller by parametric variation of the range of \(\pm 70\%\) $\pm 70\%$ .