Analysis of under-frequency load shedding considering renewable energy for isolated systems

This article focuses on the effect of under-frequency load shedding with renewable energy for isolated systems. Therefore, this article will apply PSS/E software to simulate the operating characteristics of an off-island system connected to battery energy storage in parallel in order to determine energy storage capacity. Wind energy operation and case analysis are used to integrate the systems that can improve under-frequency influence, in order to determine appropriate storage and AC–DC inverter capacities. First, the wind power generation data of isolated systems of 2011, 2012, and 2013 are used to estimate the storage and inverter capacities for 1, 2, 6, 12, and 24 h daily. With the above data of about 900 days, Gaussian distribution is applied to analyze the frequencies, sizes, accumulated probabilities, and other factors. Second, the annual electricity sales of isolated systems are used to determine more economic capacities for the battery storage energy and inverter. Finally, the economic analysis of the four cases is conducted, according to PSS/E software analysis, in order to determine the optimal capacity for battery energy storage devices and inverter