Abstract

Due to geographic isolation and heavy reliance on diesel generation, there are major energy access challenges in remote islands in Sri Lanka. In Neduntheevu (Delft) Island, electricity supply is limited, costly, and highly polluting. This study proposes an off-grid hybrid renewable energy system with EMS-based control to overcome diesel dependence, improve reliability, and enhance energy security for sustainable development.

A hybrid PV–wind–BESS system was optimised using 2025 load, solar, and wind data based on techno-economic and environmental objectives. The system includes 600 kW PV, two 250 kW wind turbines, and a 3100 kWh BESS. Optimisation of demand, battery SoC limits, generation, inverter operation, and battery performance was performed using the System Advisor Model. In parallel, an EMS developed in MATLAB manages renewable prioritisation, SoC control, load control, and system operation.

The optimised system meets the yearly electricity demand with negligible unmet load (<1%) and high reliability, while maintaining stable operation. Life-cycle emissions are estimated at 9.7-48 g CO₂/kWh, which are drastically lower than those of conventional diesel generation (>900 g CO₂/kWh). MATLAB simulations show effective EMS performance, including peak shaving of the 250 kW night demand, better controlled battery cycling within SoC limits (20-98%), improved renewable energy utilisation, and stable voltage-frequency regulation. Furthermore, techno-economic analysis indicates an LCOE of Rs 24.38/kWh (Sri Lankan Rupees) and a payback period of 15.71 years (≈ 16 years), confirming the economic feasibility compared to diesel-based systems.

The findings confirm that hybrid solar–wind–BESS systems with EMS control are technically, economically, and environmentally viable for the electrification of remote islands. The study addresses the gap in integrated design and control of islanded microgrids, enhancing energy security in the Sri Lankan context.