On the Problem of Arrangement of Hybrid Energy Storage Systems

. Electric energy storage systems are widely used in electric transport, power engineering and in order to provide autonomous power supply and load regulation of power systems. One of the ways to increase the technical and economic efficiency of storage devices is their hybridization, i. e. the creation of storage devices consisting of blocks of different types of batteries. The special literature contains no systematic analysis of qualitative and quantitative effects of hybridization and corresponding methodological recommendations for choosing a scheme and evaluating the effectiveness of hybridization. In the present article, this issue is considered from a theoretical and methodological standpoint, recommendations are given for the design of storage devices serving solar or low-power wind farms. A brief overview of data on the cost of buffering electricity with lithium-ion, lead-acid batteries and supercapacitors is made. A method is proposed for determining the necessity and degree of hybridization of an energy storage device based on the simplest dependencies of the storage parameters on the degree of hybridization. The notions of the coefficient of synergetic effect of hybridization and the degree of internal buffering of electricity are introduced. A quantitative-and-qualitative model for evaluating the effectiveness of hybridization is presented. A methodological approach is proposed for calculating the degree of internal recovery and evaluating the coefficient of synergetic effect of hybridization. It is shown that, in general, the adding of supercapacitor unit to lithium-ion batteries a does not lead to a reduction in the cost of buffering electricity due to the high ratio of the cost of buffering with a supercapacitor to the cost of buffering with lithium-ion batteries. At the same time, the economic feasibility of using supercapacitors to compensate for high pulse loads can be determined on basis of the analysis of the frequency spectrum of the load graph of the storage unit. The developed models and approaches can be used in the design of electrochemical energy storage systems for specified operating conditions.