The Effect of the Fast Frequency Response of the Solar Energy System on the Power System Dynamic Frequency Evolution

Abstract

The existence of a large-scale photovoltaic power generation system without any rotational inertia can deteriorate the frequency stability of the power system. The solar energy storage system consisted of photovoltaic power generation and the energy storage device with fast charge and discharge can provide fast frequency responses to the grid through the power electronics controls, and therefore improve the dynamic frequency security of the low-inertia system. This paper discusses the modeling and fast frequency controls, namely virtual inertia and droop control. The modified WSCC 9-bus system with high photovoltaic power penetration and low inertia serves to show the effects of the solar energy storage system’s fast frequency responses on the frequency evolutions of the new power system. The results show that in the low inertia system with large-scale photovoltaic power generation, the active power droop control of the solar energy storage system can decrease the frequency deviations, but may introduce low-frequency oscillations during the frequency evolution following a contingency; the virtual inertia control can depress both the rate of change of frequency as well as the oscillations during the frequency evaluation.