Virtual Inertia Emulation of Inverter Interfaced Distributed Generation (IIDG) for Dynamic Frequency Stability & Damping Enhancement Through BFOA Tuned Optimal Controller

Dynamic frequency stability concerns are engendered in the modern electric power system due to the large penetration of low inertia inverter interfaced distributed generation (IIDG) into the utility grid. Therefore, inertial support is needed similar to the conventional synchronous generator. From recent studies, it was observed that frequency stability is considered as one of the major challenges for the system operators and is required to be alleviated. In this methodology, the virtual inertia (VI) concept is suggested as a promising solution to boost the inertial response of IIDG. Full state feedback through a robust linear quadratic regulator (LQR) is employed to find optimal inertia and damping coefficients to emulate VI in IIDG. These coefficients are used to evaluate the additional power required to provide inertia emulation by a virtual synchronous generator (VSG). To upgrade the performance index in LQR, a bacterial foraging optimization algorithm (BFOA) is suggested for optimal parameters (weights) selection in the problem search space. The proposed optimal controller ameliorates VI dynamics and brings system frequency faster to the nominal value and allows more penetration of IIDGs. Time-domain simulated results and observed test system eigenvalues corroborate the effectiveness of a proposed controller. Time-domain simulations have been obtained using MATLAB/Sim Power Systems toolbox, and the LINMOD function in MATLAB is used to linearize the suggested system.