Characteristic of small-scale BESS for HOTT generation system

Integrating a small-scale battery energy storage system (BESS) with a hybrid offshore-wind and tidal turbine (HOTT) generation system can smooth out the intermittent power generated by the offshore-wind turbine. In this system, tidal turbine is connected to an IGBT bi-directional converter and offshore-wind turbine is connected to a diode rectifier. They are connected at DC side. The power flow of tidal turbine is controlled by switching of the bi-directional converter and wind fluctuation is compensated by changing tidal turbine output. There are some problems to compensate the offshore-wind power fluctuation by the tidal output power. First, tidal turbine cannot change its output very fast because of its inertia. So there is some delay to control the output. Another problem is the loss of tidal turbine generated power due to change of the slip. However, the capacity and response speed of tidal turbine is inadequate to achieve good compensation. That's why it is required to integrate BESS with HOTT generation system to enhance reliability, increase throughput of existing grid infrastructure and yield various ancillary benefits such as to reduce system losses and improve power factor control. As a large-scale BESS is still an expensive option for renewable resources, an optimal control strategy is necessary for the use of small-scale feasible BESS. In this paper, BESS is connected to help tidal turbine to compensate fast fluctuations of offshore wind turbine. The effect of the battery is investigated through simulations. This is a small capacity simulation study which is prepared to use in our small experimental model HOTT system with BESS.