Design on triple bi-directional DC/DC converter used for power flow control of energy storage in wind power system

Abstract

A triple bi-directional DC/DC converter used for power flow control of energy storage in wind power system is designed. Firstly, the paper analyzes energy flow characteristic of wind power system containing hybrid energy storage (the battery and the supercapacitor). Secondly, working principle of the triple bi-directional DC/DC converter is explained and mathematical model is constructed. Then, based on the model, control unit consisting of voltage outer loop and current inner loop is designed. To ensure the consistency of working state of batteries in parallel, a novel current-sharing strategy is proposed based on battery SOC (state of charge). To realize energy distribution between the battery and the supercapacitor, a one-order low pass filter is used to detach the low frequency component in feedback voltage. The simulation results show that the converter can effectively regulate the load voltage and reasonably distribute the power between both energy storage elements. © 2011 Springer-Verlag Berlin Heidelberg.