Research On The Efficiency Enhancement Range Of The Energy Storage Converters

The source and load of energy storage converter have the characteristics of wide power range and strong fluctuation.In addition,the energy storage element itself operates in the case of power fluctuation.However,the existing energy storage converter has a narrow operating range,which makes it difficult to achieve efficient energy utilization in a wide range.Therefore,widening the efficient operation range of energy storage converter is an urgent problem to be solved.Firstly,the efficient operation range of two-stage energy storage converter under power fluctuation is studied.A Two-Stage Energy Storage Converter is taken as an example,to describe the power loss modeling.The efficiency enhancement range of the Two-Stage Energy Storage Converter is analyzed based on the power loss model.The results show that under the condition of charge-discharge balance,the efficiency enhancement range can not be widen by the energy storage elements.Secondly,the interaction between power distribution of energy storage elements and system efificiency is studied based on energy stored quasi-Z source converter.First,the reconstructing effect of energy storage elements on the internal current of impedance network is described.On this basis,the loss model of energy storage quasi-Z source converter is established,and the loss characteristics of the converter with energy storage elements embedded are analyzed.It is found that the loss of energy storage quasi-Z-source converter is U-shaped with the increase of the power of energy storage elements.The boundaries and efficiency enhancement range are described,which can be reference for power distribution strategy of energy storage components.Compared with quasi-Z-source converter,the efficiency of energy storage quasi-Z-source converter can be improved by 8%.Finally,the influence of power distribution between energy storage components and diesel generator under fluctuating loads on the high efficiency operating range and economy of the system is studied.Considering the efficiency curve of diesel generator,power allocation of battery pack and fluctuation of electric load,a loss model of diesel/storage hybrid system is established,and the efficient operation range of diesel/storage hybrid system is studied from the angle of matching power between energy storage components and diesel generators.The results show that the addition of energy storage is conducive to widening the efficient operation range of the system.On the basis of comprehensive consideration of wide range,high efficiency and economy,the power allocation criteria of diesel generator and energy storage components in diesel/storage hybrid system are proposed,which provides guidance for the design of diesel/storage hybrid system.