Optimal Investment Decision for Cotton Farm Microgrid Design

The integration of renewable energy sources (RESs) into distributed microgrid systems has been widely applied in agriculture, and in particular in cotton farms. Due to the specific irrigation periods and non-irrigation periods during cotton growth, and the inherent intermittent characteristics of RESs, the design of a cotton farm microgrid system becomes challenging. Finding the optimal size of the RESs for a cotton farm microgrid needs to consider not only the energy demand for cotton irrigation but also the investment cost and the payback period. This paper presents an optimization model for cotton farm microgrid design, which explores available RESs and energy storage options to ensure reliable power supply from renewables. Furthermore, the designed microgrid utilizes solar photovoltaic (PV) units and wind turbine generator as RESs together with battery storage and demonstrates the supply and demand relationship between the microgrid and pump loads. By using RES power supply, renewable energy is optimally utilized to satisfy the seasonal loads demand, and the grid power is used as a backup power source. The objectives of optimization include investment cost, operating cost and simple payback period. In order to solve the underlying optimization problem, this paper adopts YALMIP MATLAB Toolbox. A case study is undertaken using historical energy consumption data for a cotton farm in Gunnedah, New South Wales, to verify the applicability of the proposed approach.