Posters

Abstract

We present an approach to optimize the operation of an Energy Island that includes a Battery Energy Storage System (BESS), green hydrogen production, and that has High-Voltage Direct Current (HVDC) links to several offshore wind parks and several countries’ grids. HVDC is the technology chosen for most current energy island projects because it offers reductions in power losses over long distances, and better control options.  The objective of the optimization is to maximize, for each time window, the revenue from the system considering the electricity market prices in the different connected countries. The hydrogen demand is preset for each time window on the total analysed period using a rolling-horizon approach. The system's nonlinear power flow equations, along with the voltage and HVDC line thermal constraints and the available power at each connected wind park, are convexified using a second-order cone relaxation and incorporated into the mathematical programming model as constraints. A mixed-integer linear programming model is used to accurately represent the operational constraints and decision-making processes of the BESS. In addition, we use a quadratic model for the hydrogen system, employing a system identification approach to determine the model parameters based on real or simulation-based measurements. Finally, the quadratic model is convexified and incorporated into the optimization model, resulting in a fully convex mathematical programming approach for the optimal operation of energy islands.  The case study is based on the future Elia energy island that connects the future Princess Elisabeth I (700 MW), II (1400 MW), III (1400MW) wind parks to Belgium, Denmark and the UK. We assume an infrastructure based on HVDC links. We used wind timeseries data available for the sites, made assumptions on the wind parks’ layout and modelled wake losses to arrive at a timeseries for the available power from each wind park. Then, we optimized a year of operation of the integrated system of the energy island and its connections through the optimization setup described above. In our initial studies, we use a BESS storage capacity of 3500 MWh and an electrolyser capacity of 150 MW and compare the revenue improvement that can be attained through the optimal use of the storage options and the distribution across the different connected countries.