A fast methodology for solving power flows in hybrid ac/dc networks: The European North Sea Supergrid case study

This paper presents a sequential algorithm for power-flow studies in hybrid ac-dc networks. The algorithm developed, based on the Newton-Raphson method, can be applied to any power system configuration, without constraining the topology of either the ac or of the dc grids. Combinations of multiple non-synchronized ac systems and multiple dc systems can be solved. The algorithm includes simplified HVDC converter representations, for both VSC and LCC technology, needed to study the steady-state interaction between ac and dc systems. The proposed algorithm for hybrid ac-dc power flow calculations is based on MATLAB and uses the Newton-Raphson power-flow routine from MATPOWER to solve both the ac and the dc power flows. This paper presents the algorithm principles, its flowchart diagram and implementation aspects. Finally, through the developed tool a study on the benefits and impacts when connecting large amounts of offshore wind energy to the European transmission network is studied to demonstrate the applicability of the tool to large scale systems