Online capable optimized planning of power split in a hybrid energy storage system

A hybrid energy storage system is an energy storage consisting of more than one type of energy storages combining their advantages. The system treated in this paper consists of NiMH batteries and double layer capacitors. The power flow needs to be split up between the storage devices. This defines a multi-objective optimization with the minimization of energy loss and maximization of the abilty to react on unforeseen power demands as objectives. So far this had to be optimized by offline methods on typical situations. This paper presents an optimization method that is capable of planning the power flow split at run time. For this purpose a Pareto Point search algorithm is used which geometrically constructs a function to minimize in the image space of objective functions. This is done by using single-objective optimization to find the endpoints of the Pareto Front. The function to be minimized then defines a trail on which the optimal solution for a given trade-off parameter is searched.