Power electronics as grid interface for actively controlled wave energy converters

Off the coasts of Europe, the potential for power generation from offshore renewable energy is huge and the technology for offshore wind power is already becoming available. Achievement of a cost-effective technology is the main concern for commercial development of wave energy converters (WEC). It is widely recognized that some kind of active control of the primary conversion is needed in order to increase the electricity production and hence improve the economical payback. Moreover, if high penetration levels are going to be reached with offshore renewables, barriers to interconnection will be encountered. These barriers need to be identified and the technologies that will mitigate the impacts on the power system stability need to be investigated. Power electronics will be the enabling interface that will permit wave farms to act as one large power plant. This paper presents known approaches for maximizing production from wave power through active control, and discusses how these can be implemented by power electronics controllers used as interface with the power network. Three alternatives of power electronics interface are presented through three case studies for active control of WEC, power conditioning, and stability. Simulation results indicate the role of the power electronic interfaces in the active control of the wave energy converters and in network interactions.