Design and Optimization of Isolated Wind-Battery Systems Incorporating Multiple Wind Generators

Systems consisting of multiple wind-generators along with a single battery bank are a sustainable alternative for supplying the energy requirements of remote locations not connected to the national grid. In this paper, a methodology for sizing and optimizing wind-battery systems employing multiple wind turbines is proposed. Uncertainty in wind resource availability is taken into account by formulating the problem as a chance constraint. Based on a time step simulation, subject to different technical and physical design constraints, the entire solution space in terms of the system design variables viz., generator rating, rotor diameter and battery bank size for a specified number of wind turbines and reliability requirement is generated. The domain containing all feasible solutions is the design space and it is a function of system reliability requirement and the number of wind turbines. From the design space of multiple wind turbine-battery systems, it is shown that with an increase in the number of wind generators, the rotor diameter, generator rating of individual turbines as well as battery bank size can be minimized along with a benefit in the overall cost of energy (US$/kWh). Additionally, by increasing the number of wind generators it is possible to comply with a stringent power supply reliability target which would otherwise not be possible. The strength of the proposed methodology lies in the visualization of alternative solutions and identification of the minimum and the maximum limits of various system design variables.