Lithium-ion battery smoothing power fluctuation strategy for DC microgrid

Abstract

Microgrids containing renewable energy, energy storage systems and loads have been widely used because of their advantages of environmental friendliness. The role of the energy storage system is to balance the power fluctuation of renewable energy and load and maintain the stability of the power of the microgrid. At present, a large number of studies point out that the use of lithium-ion batteries and supercapacitors (SCs) composed of hybrid energy storage system has better performance. In this paper, we use high-capacity lithium-ion batteries instead of SCs to smooth the microgrid power fluctuations: when the microgrid power fluctuations are small, low-capacity lithium-ion batteries will be alone to smooth the power fluctuations; when the microgrid power fluctuations are medium, low-capacity and high-capacity batteries will be decomposed by wavelet packets to suppress power fluctuations; and when the microgrid power fluctuations are large, high-capacity batteries will smooth out power fluctuations on their own. The contribution of this paper is that we use high-capacity lithium-ion batteries instead of SCs because SCs are very expensive and their features are very small. The effect of the strategy proposed in this paper is verified by simulation. The battery can quickly stabilize the sudden increase in bus fluctuations; if the actual situation is considered, the time will be shorter.