A Reliability Evaluation of Offshore HVDC Grid Configuration Options

This paper details a methodology for investigating the reliability of different offshore grid design options for the connection of offshore wind power to shore. The methodology uses a sequential Monte Carlo-based technique that enables the investigation of realistic offshore phenomena, such as the weather dependency of component repair times. A number of case studies are examined for the connection to shore of a cluster of far offshore wind farms and a cost benefit analysis is performed which compares the capital costs, electrical losses, and reliability of each. There is found to be a clear value in options that have inherent redundancy and alternative protection strategies, which avoid the use of expensive dc circuit breakers, that are shown to be potentially viable. It is also found that low probability, high impact faults, such as transmission branch failures, are a key driver behind overall grid reliability.