HyDesign: a tool for sizing optimization for grid-connected hybrid power plants including wind, solar photovoltaic, and Li-ion batteries

Abstract. Hybrid renewable power plants consisting of collocated wind, solar photo-voltaic (PV) and Lithium-ion battery storage connected behind a single grid connection can provide additional value to the owners and to society in comparison to individual technology plants such as only wind or only solar-PV. These benefits become significant in projects that have requirements to supply a certain amount of energy during peak hours given a set of grid capacity constraints or when the plant is selling the electricity with time-varying electricity prices. The hybrid power plants considered in this article are connected to the grid and share electrical infrastructure costs across the different generation and storing technologies. In this article, we propose a methodology for sizing of hybrid power plants as an optimization problem that maximizes the net present values over capital expenditures and compares it with standard designs that minimize the levelized cost of energy. The sizing problem formulation includes turbine selection (in terms of rated power, specific power and hub height), a wind plant wake losses surrogate, simplified photo-voltaic panel degradation, an internal energy management system operation optimization and battery degradation. The multi-disciplinary optimization problem is solved using a new parallel "efficient global optimization" algorithm. This new algorithm is a surrogate-based optimization method that ensures a minimal number of model evaluations but ensures a global scope in the optimization. The methodology presented in this article is available in an open-source tool called HyDesign. The hybrid sizing algorithm is applied for a peak-power plant use case at different locations in India where the renewable energy auctions impose a monetary penalty when energy is not supplied at peak hours.