Hybrid Energy Storage System Planning Method of DC Distribution Network Based on Energy Storage Battery and Super Capacitor

Energy Internet is a hot spot of research and practice in the field of energy at home and abroad. DC power distribution technology is an important element of energy Internet. How to plan the type and capacity of energy storage system (ESS) is a problem worthy of attention when designing the optimal energy conversion path in the energy Internet, especially in the DC distribution network. The proper type and capacity of ESS can effectively suppress DC voltage flicker and improve the system operation stability and fault crossing ability. In this paper, the hybrid energy storage scheme of energy storage battery and super capacitor is adopted in DC distribution network, and the discrete Fourier spectrum analysis of power demand sample data is carried out to obtain the basic power in low frequency and fluctuating power in high frequency. The energy storage battery with slow dynamic response speed is used to match the power demand of low-frequency segment, and the super capacitor with slow dynamic response speed is used to match the power demand of high-frequency segment. The influence index of SOC over limit times of energy storage system is introduced to seek the critical value of ESS capacity planning. Finally, the proposed hybrid energy storage planning method is verified by the case studying.