Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Generator Requirements and Functionality for Ocean Energy Converters Dr. Dara O’Sullivan Hydraulics & Maritime Research Centre, UCC 21 st Oct 2010

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Overview  Evolution of generator technology  Common requirements of OE generators  Device specific requirements of OE generators  Generator functionality within OE devices

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Traditional Generators  Synchronous  Fixed speed  Fault current – 3-4 pu  Field regulated reactive power Turbine

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Technology Migration Asynchronous Two-speed Variable Speed Gearless Driven by Wind Turbine Development

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Technology Drivers  Energy Capture – MPPT  Mechanical Robustness – drive-train torque loads  Grid Connect Codes  Reliability

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility What about OE Generators?  Are the issues the same as wind?  What are the differences? = ?

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Generator Requirements Common Device Specific Environmental Grid Connect Speed Range Torque Rating Custom or OTS

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Operation and Maintenance  High cost – minimise requirement!  Tidal – Expensive to perform at best  Wave – weather windows

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Brushed Generators  Typical brush life – 3-8k hrs  Twice yearly maintenance/replacement – corresponds with wind industry best practice  Brushes are considerably more inaccessible in many OE devices  Brush film formation disrupted in oscillatory current flows – significantly enhanced wear Brushed generators may be unsuitable for OE devices

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Corrosion  Saline air exposure  Not air conditioned generator enclosures  PMGs sensitive  Special coatings available e.g. VACCOAT

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Mechanical Design  Significant heave and pitch accelerations in many devices e.g. OWC:  Pitch: 7deg/s 2  Pitch: 4 m/s 2  2x bearing rating due to gyroscopic loads  Robustness important

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Grid Connection  Voltage Limits  Voltage Distortion  Flicker  Reactive Power Control Requirements  Active Power Control Requirements  Fault Ride-Through

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Voltage Distortion HV MV LV t P elec t Local Voltage 10s

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Generator Grid Connect Options Fully variable speed Reactive power control Controlled fault ride-through ‘Fixed’ speed No reactive power control No fault ride-through Fixed speed Reactive power control Controlled fault ride-through Limited variable speed Limited reactive power control Controlled fault ride-through

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Device Specific Requirements  Oscillating Water Column  Hydraulic Point Absorber  Overtopping Device with Hydro PTO  Direct Drive Point Absorber  Tidal Turbine  Tidal Oscillating Hydrofoil

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Oscillating Water Column  Air turbine with limited range of efficient operation  Variable speed  OTS design  High peak-to-average torque ratio

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Hydraulic Point Absorber  Generator design strongly linked to hydraulic circuit design  Fixed speed possible  OTS possible  Hydraulics can absorb torque pulsations Wavebob Prototype

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Overtopper  Conventional hydro turbines  High pole or gearbox coupled  Rating equals maximum mean power  Fixed speed possible Wave Dragon prototype

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Direct Drive Point Absorber  Direct drive linear or rotary generator  Custom design  Must have power electronics conversion  Low speed and high torque  High part load efficiency very important

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Tidal Devices  Tidal turbines  Marine equivalent of wind turbines  Higher gear ratios  Oscillating hydrofoils  Similar to hydraulic point absorbers

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Functionality  Determines how the generator sits within the power conversion chain 1.Power conversion 2.Prime mover efficiency optimisation 3.Power smoothing 4.Damping control

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility Summary OEC Prime Mover Speed Range Generator Peak Torque Range Generator Type OWC rpm 2-4 pu; reduces with added inertia VS SCIG/SG/PMG PA - hydraulic rpm Close to 1 pu with high accumulator storage, up to 4 pu as storage reduces  FS SG/SCIG-SVC for high storage designs  VS SG/PMG/SCIG for low storage designs Overtop rpmClose to 1 pu  GBC: FS SG/SCIG-SVC or VS PMG/SCIG  Low speed VS PMG PA - direct 0-3m/s rpm 2-5 pu; reduces with added inertia  Linear: PMG (custom)  Rotary: GBC VS SG/PMG Tidal turbine 0-10 rpmClose to 1 pu GBC, FS SG/SCIG-SVC or VS SG/PMG/SCIG Tidal hydrofoil rpmClose to 1 puFS SG/SCIG-SVC for high storage designs or VS SG/PMG/SCIG for low storage designs

Hydraulics & Maritime Research Centre hmrc.ucc.ie Charles Parsons Energy Research NUIM Ocean Energy Seminar, October 21 st 2010 National Ocean Test Facility THANK YOU QUESTIONS?