Inertia Emulation in Low Inertia Power Systems Considering Frequency Measurement Effects

Inertia emulation has been considered as a promising solution to improve the frequency stability of stand-alone microgrids (MGs) with high penetration of renewable energy sources (RESs). To effectively emulate system inertia using power electronic converters, it is necessary to accurately estimate the actual system frequency. The phase-locked loop (PLL) has been widely used in frequency estimation; however, it is associated with measurement delays that may compromise the stability of a M G if the disturbance is severe. This paper proposes a frequency-locked loop (FLL)-based inertia emulation strategy in a stand-alone MG to improve the frequency response of the system. The performance of the proposed strategy is compared to a conventional PLL-based inertia strategy under varying M G operating scenarios. The results show that the FLL-based inertia emulation strategy has a fast transient response, damps oscillation, and reduces frequency deviation. The frequency stability and resilience of the M G are shown to be preserved.