Exploring the Potential Benefits of Emerging Maintenance Technologies in Offshore HVDC

Abstract

Over the past decade, wind power has experienced rapid development. Offshore wind farms are evolving towards two characteristics: higher rated power and farther from coast. However, High Voltage Alternating Current (HVAC) systems face significant disadvantages when dealing with these two new characteristics. This has led to the emergence of High Voltage Direct Current (HVDC), as its cable losses are lower than the equivalent AC systems during ultra-long-distance power transmission. However, the specific feature of HVDC platform that being located extremely far offshore results in increased difficulty of performing maintenance. Inability to carry out maintenance promptly or prolonged maintenance duration can extend downtime, thereby leading to higher economic losses. To mitigate the occurrence of failures and reduce the duration of maintenance, preventive maintenance is imperative. Given the relatively brief development history of offshore HVDC, there exists a research gap in the application of preventive maintenance to these systems. Considering the recent emergence of many new maintenance technologies, exploring the potential possibilities and benefits of implementing these emerging technologies in the preventive maintenance of HVDC platforms is of significant academic interest. The research questions include identifying the critical equipment/systems within offshore HVDC platforms through analysis, exploring emerging maintenance technologies that might be applicable to these equipment/systems, and investigating the benefits by applying these emerging technologies. This thesis employs some methods from ISO 14224 to conduct system analysis of the HVDC platform and uses some methods from Reliability Centered Maintenance (RCM) to analyze the critical equipment/systems. Subsequently, conceptual models for the baseline case, which uses traditional maintenance methods, and the solution case, which uses emerging maintenance technologies, are developed. Finally, computational models for the baseline case and solution case are developed in AnyLogic, and then the respective numbers of outage days and associated expenditures for each case are simulated. The conclusions drawn from this study are as follows. The most critical equipment/systems in offshore HVDC platforms are the transformer and converter. Three emerging maintenance technologies applicable to these two are identified: online Dissolved Gas Analysis (DGA) for transformer, intelligent algorithm for monitoring converter submodules, and robot for inspection. By comparing the simulation results of the baseline case and the solution case show that the latter achieves an 80.33% reduction in outage days and a 79.89% reduction in related expenditures.