Interfacing a Battery Energy Storage System (BESS) with a Wind Farm with DC Collector System via a Flyback DC-DC Converter: Modelling, Control Strategy and Performance Analysis

Because of the intermittent nature of wind farm output power, large developments of grid-connected wind farms involve large fluctuations of the frequency, power and voltage in the grid. Thus, the output power of wind farms has to be controlled to limit these fluctuations. Integrating a battery energy storage system (BESS) into a wind farm can improve the wind farm- output dynamic properties. The simulation model of a grid-connected DC wind farm employing BESS is presented in this paper. The interface between DC wind farm and BESS is provided through an isolated flyback DC-DC converter. The dynamic performance and control strategy of the combined system, i.e. "BESS, flyback DC-DC converter and DC wind farm" is investigated. Through a proper coordination of the charging and discharging processes of BESS using the flyback DC-DC converter, it is demonstrated that the DC wind farm's output voltage and power can be controlled to a constant value. Several simulations are carried out using MATLAB and show that the proposed DC grid configuration has the potential to significantly improve the wind farm's output performance.