Capacity optimization of The Hybrid Energy Storage System for Suppressing Intermittent Loads

At the ends of the distribution network, the long power supply distance and weak grid structure often lead to the power supply problems, especially when seasonal and periodic load fluctuations occur. For these intermittent loads, the peak-to-valley power difference can achieve up to nearly ten times. This difference could lead to power quality problems such as custom-side voltage sag and three-phase voltage imbalance. In this paper, a hybrid energy storage system (HESS) including both power-density and energy-density storage components is used to suppress the power fluctuation of the intermittent load. The intermittent load was modelled by analyzing its frequency characteristics with an algorithm combining empirical mode decomposition (EMD) and Hilbert spectrum analysis. Thus, the high and low frequency components of the intermittent load are determined. Then, according to the proposed power allocation strategy, the rated capacity of the HESS was designed. Finally, simulation experiments based on actual examples verified the effectiveness of the proposed methods.