Electrical Systems for Wave Energy Converter Arrays Fergus Sharkey School of Electrical and Electronic Engineering Supervisors: Michael Conlon and Kevin Gaughan May 17 th 2013

Outline Introduction and Motivation for Research Wave Energy, Wave Energy Converters and Arrays Challenges for WEC Array electrical systems Techno-economic optimisation and design tools Publications Future Research Conclusions

Introduction Graduate of DIT Kevin Street Employed by ESBI since 2005 Seconded to Wavebob (TPA) Part of ESB Ocean Energy Team PhD Research in DIT Kevin Street since 2010

Motivation for Research Lack of industry experience of electrical systems for WEC arrays – convergence required Technology developing before application understood WEC developers lack electrical knowledge and can develop devices with inherent electrical issues 4

Wave Energy and Wave Energy Converters (WECs) There are numerous ways described to convert wave energy (mostly to electrical power) Devices are classed on location (onshore, near-shore, deepwater) And capture method (point absorber, terminator, attenuator, oscillating water column) 0o0o 30 o 60 o 30 o 60 o Up to 6GW ‘practical accessible’ installed capacity

“Wave Farms”

Offshore Wind and Wave Test Sites

Wave Farm Requirements / Challenges Individual device ratings are lower (~1MW) Devices are divergent and may have low capacity factors Water depth and distance from shore is larger Devices require connection and disconnection for installation and maintenance Devices are not fixed structure therefore interface to network is complex Array spacing is driven by different factors Sites are high energy and cable installation and protection may be a challenge Test site experience can help up to a point

Techno-Economic Optimisation 1.State of the art – Offshore Wind and Wave Test Sites 2.Wave Farm Electrical Network Roadmap 3.Key Interfaces 4.Economics of WEC Array Electrical Networks 5.System Issues – Flicker and Grid Access

Macro and Micro Perspective Hz

Publications ConferenceTitleDate WREC 2011Investigation of Wave Farm Electrical Network ConfigurationsMay 2011 EWTEC 2011Dynamic Electrical Ratings and the Economics of Capacity Factor for Wave Energy Converter Arrays Sept 2011 ICOE 2012Practical Analysis of Key Electrical Interfaces for Wave Energy Converter ArraysOct 2012 ICOE 2012Voltage Flicker Evaluation for Wave Energy Converters – Assessment GuidelinesOct 2012 EWTEC 2013Impacts on the Electrical System Economics from Critical Design Factors of Wave Energy Converters and Arrays Sept 2013 UPEC 2013The Domestic and Export Market for Large Scale Wave Energy in Ireland and the Economics of Export Transmission Sept 2013 Journal IET RPGResource Induced Voltage Flicker for Wave Energy Converters – Assessment ToolsMay 2013 IJMEMaximising Value of Electrical Networks for Wave Energy Converter ArraysJune 2013 IET – Ocean Energy Electrical Systems Book ‘Economic Challenges for Ocean Energy Electrical Systems’July 2013

Selection of Results Network Configuration Relat. Cost Radial Network (A)1.0 Single Return Ring Network (B) 2.58 Single Sided Ring Network (C) 1.8 Double Sided Ring Network (D) 1.69 Star Cluster Network (E) 1.54

Results… continued Hz

Ongoing / Planned Research Main focus is on completing outstanding papers EWTEC Paper complete and submitted – Impacts on the Electrical System Economics from Critical Design Factors of Wave Energy Converters and Arrays UPEC Paper ongoing with assistance from DIT undergrad student – The Domestic and Export Market for Large Scale Wave Energy in Ireland and the Economics of Export Transmission IJME Journal Paper Revisions due May 2013 Plan to prepare and submit Thesis by end 2013

Conclusions Organised, comprehensive top-down approach taken to research. – Electrical Networks for WEC Arrays – Key Interfaces – Economics – System Issues such as PQ and Grid Access Disseminated through multiple publications Thesis will be first complete academic examination of electrical systems for wave energy converters Practical focussed research and developed methodologies, tools and conclusions will be valuable to industry at current stage.