Research On Control Strategy And Capacity Optimization About Hybrid Energy Storage System

With the maturity and the development of the wind power technology in recent years, the influence of grid-connected wind power on the power system has gained much attention. Wind energy has become the energy with the most large-scale exploitable potential since it has the advantages of less pollution and larger reserves. However, it also introduces a series of problems such like the electricity quality and the system reliability due to its intermittent and uncertain nature. Still, this hybrid energy storage system is effective in smoothing the wind power fluctuation as well as increasing the efficiency of the wind power utility ratio that it has become a hot research topic. Under such context, this paper conducts research in the aspects of the wind power fluctuation, the electricity storage, the control strategy of hybrid energy storage system, and the capacity optimization of energy storage. The contents of this paper includes:First, this paper researches and analyzes the wind power fluctuation in terms of the extreme value of power fluctuation and the probability theory, combined the grid-connected wind power standard of the power system of the State Grid and the actual data monitored in the wind power plant. The results shows that the 1min fluctuation amount does not meet the grid-connected wind power standard of the power system of the State Grid and 10min fluctuation meet the standard, which verified the importance of wind power fluctuation smoothing. It introduces several other mature energy storage technologies and studies in the perspective of working principle and all kinds of technical analysis. Based on their advantages and disadvantages, it states the limit of single storage medium that provides proof basics of introducing the hybrid energy storage system.Second, it provides a State of Charge feedback control strategy. Such strategy adjusts expected output power according to the load condition of the storage while ensuring the smoothing wind power fluctuation effects, in order to optimize the operating condition of the storage system and prevent the deep-charging and deep discharging. As far as the hybrid energy storage system is concerned, this paper conducts analysis of the power allocation based on the sliding filter principle in the battery-super capacitors hybrid energy storage system, and proposed a power two-time adjustment strategy to adjust the working condition of super capacitors. Therefore, it optimized the hybrid system running condition.Third, this paper proposed an optimization method of the capacity allocation in the storage-super capacitors hybrid energy storage systems. This method jointly considered the opposite relation between the smooth effect and the storage system costs, meanwhile, it introduces the effects of the abandoned energy and the lack of the smooth energy. With the objective function of economical index, it builds a capacity optimization model of the storage-super capacitors hybrid energy storage system. The objective function consists of basic cost and running cost. This two kinds of cost represent procurement costs, relocation costs and the economical cost caused by the unreasonable working states. It verified using the Particle Swarm Optimization(PSO) and analyze the results according to several different evaluation matrix. Finally the result proves the effectiveness and feasibility.