Network redundancy versus generation reserve in combined onshore-offshore transmission networks

Abstract

A large integration of offshore wind power plants and the construction of an offshore transmission network is expected for the next years. This network is also expected to interconnect onshore transmission systems. A key question to this endeavour is whether this offshore network should be n-1 redundant like the onshore network, or whether the onshore power system is strong enough to cope with failures of the offshore network. To address this issue, this paper provides a comprehensive investigation on various possible causes of power imbalance, like generator failures, load/wind prediction errors and offshore network failures. General insight is obtained about which causes of imbalance are the most severe and whether n-1 redundancy is required in offshore networks. The main finding is that onshore reserve generation can serve as redundancy for the offshore network in the studied power system. Nevertheless, the determination of the level of offshore wind capacity until which this conclusion holds remains as an open research issue.