WP5: Optimization of North Sea Transnational Grid solutions

Multi-objective optimization and multi-criteria decision making will be used to optimize the Transnational Grid options chosen in WP2 and further developed in WP3 and WP4.

The design of complex engineering systems, such as the North Sea Transnational Grid, requires application of knowledge from several disciplines (multidisciplinary) of engineering and economy (electrical aspects of multiterminal converter, control aspects, grid aspects, costs) The interdisciplinary nature of complex systems presents challenges associated with modeling, simulation, computation time and integration of models from different disciplines. The increased complexity of systems as well as the increased number of design parameters in the optimization results in the necessity to use mathematical system models and the application of optimization techniques. An adequate system model is built and optimization algorithms are employed to determine the optimal parameters for the system based on model results.

A well known optimization method used gradient search algorithns. A major barrier to the use of gradient based search methods is that complex multidisciplinary design spaces tend to have many apparent local optima. Therefore a new method, based on multi-objective optimization and multi-criteria decision making, called Progressive Design Methodology (PDM), will be used. The Progressive Design Methodology is a three-step design process. In the first step a simple model of the components of a system is developed and the problem is reformulated as a Multi-Objective Optimization Problem (MOOP). In the second step the results obtained in the MOOP process are analysed and a small set of feasible solutions is selected. In the final step, a detailed model of the variants of the system, as selected from the previous set, is developed and the optimization variables of the system are fine-tuned. The objective of optimization will be to determine a configuration of the North Sea Transnational Grid with low levelized production cost, high power quality, high reliability and high low voltage ride through capability. The set of optimization objectives can be extended and the optimization variables will be the result of inventory.