| In twenty-first century, the world’s energy situation has changed. On one hand, in order to solve the problems of high pollution level of tranditional fossil fuels, the development and utilization of new and renewable energy technologies are more widely; on the other hand, in order to solve the problems of tranditional power system away from the load center, government promotes mircogrid which could access distributed generation. Because of the randomness of output power of new energy and the need of mircogrid own composition, Battery Energy Storage System (BESS) is increasingly important, which could achieve peak load shifting, improve the quality and stability of power system and balance power fluctuation. High power converter is an important part of BESS, and it is also the main research content of this paper.Firstly, this paper analyzes the topology and principle of high power converter for BESS. A type of bi-directional converter for implementing large capacity BESS is present in this paper, which is composed of multiple DC/DC converters and a PWM converter. The parameter design method of these two parts is introduced, including the DC-side capacitance, LCL filter, inductance, battery-side capacitance and so on.Secondly, this paper analyzes the control strategy of this converter. According to the principle of DC/DC converter and PWM converter, the coordination control strategy of these two parts is introduced, and constant current control strategy, constant dc-voltage control strategy and droop control strategy are put forward. A simulation model of BESS on MATLAB is built, and the simulation results show that these control strategies are feasible.Finally, experiments of100kW high power converter are carried out, including charge/discharge experiments, constant current mode and droop control mode experiments. The experimental waveforms and data show the correctness of the research results and the feasibility of the design scheme. |
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