Technical challenges linked to the grid dynamics in the context of energy islands

Details

Supervisors

De Jaeger, Emmanuel

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électricien, à finalité spécialisée

Abstract

In the context of the development of energy islands that harvest the power produced by wind farms, a hybrid link was introduced in the second modular offshore grid designed by the Belgian transmission system operator Elia. This hybrid link refers to the parallel use of an AC and a DC transmission link. Regarding the power flow, this link raises questions associated to the active power losses and to the reactive power generated by offshore cables. This thesis addresses the design of an active power dispatch controller with the goal of minimizing active power losses, and covers the development of reactive power compensators through the use of shunt reactors, so as to mitigate the effects of a reactive power imbalance (namely the rise of the cable voltage and the increase of the active power losses). In a wider scope, this work deals with the reasons behind the existence of limits of cable length and it assesses the robustness of the future second modular offshore grid. The outcome of this work demonstrated that the DC part of the hybrid link should be preferred to the AC one so as to minimize active power losses. Regarding the shunt reactors, it has been shown that an equal compensation at both cable ends provides the best results in terms of voltage and current increase. The limitation in cable length has been explained via the active power losses, rising along with the distance of transmission. Finally, from the robustness point of view, it has been shown that the future grid could not ensure a zero power outage in case of some particular faults.