Optimal Sizing and Operation of Stand-Alone Hybrid Power Systems: Case Study of Agios Efstratios

The main goal of this study is to contribute to the design of an optimized hybrid renewable power plant for the island of Agios Efstratios. The initial step is to analyze the attributes and applications of various energy generation and storage technologies and focus on the most suitable ones for autonomous applications. Based on the island’s wind and solar potential, wind and solar systems appear as the most competitive solution while battery technologies provide the most feasible option for storing the excess energy. In the next, simulation models are developed in HOMER software. Various ratings of Renewable Energy Sources and Energy Storage Systems are considered and the most feasible combinations with respect to the Net Present Cost are calculated. The results have been assessed according to three scenarios, each of them representing a different policy and encountering several constraints. Afterwards, steady-state analysis of the network is carried out considering typical cases of seasonal demand. The static model is developed in DIgSILENT PowerFactory software and the system’s behavior is investigated. In the following, the optimal placement for the wind, solar and storage units is discussed. The main criterion for this evaluation is the improvement of steady-state voltage magnitude and minimization of power losses. The final part analyzes the hybrid system’s stability. An aggregated dynamic model is constructed based on built-in models from DIgSILENT library. The results highlight the battery’s capability to manage the frequency and voltage variations under various cases of generation/load unbalance.