The Integration of Renewable Energy onto the Existing Grid

1. The Integration of Renewable Energy onto the Existing Grid Dr Norman MacLeod Technical Director, HVDC

2. Hydro-electric Power Run of the river schemes use the natural force of the water to turn the turbines • Minimal environmental impact Dams create a head of water which turns the turbines • Significant environmental impact Micro-hydro generation • Diverting water from local streams • Connected to the local community

3. Wind Power On-shore • wind farms are typically 10 – 50MW • Turbines typically up to 3MW rating • Connected at distribution voltage level Off-shore • wind farms are typically up to 600MW (AC connected) and 1200MW (DC connected) • Turbines up to 8MW • Connected at transmission voltage level

4. Solar Power Domestic • Connected to the low voltage distribution grid • Supplies local loads and any excess is fed into the distribution grid Commercial • Photovoltaic panels generate electricity at low voltage DC • Conversion from DC to AC is needed for connection to the transmission grid

5. Renewable Energy Sources Other sources • Wave power – in development • Tidal power – barrage schemes in use • Tidal power – submerged turbines in development • Bio-mass – in use as a coal replacement • Electric vehicles – both a load and a generator

6. The Issues • Intermittency of power generation • Remoteness of power sources from load centres • Impacts on system stability - • Loss of inertia on the network – closure of rotating plant • Harmonic distortion – Irish Grid Code • Low voltage ride-through – Irish grid Code

7. The Solutions • Diversity of power sources • Fossil fuels + renewables • Grid enhancement • AC transmission lines and/or HVDC embedded links • HVDC interconnectors to neighbouring grids (UK, France) • Dynamic reactive power devices • SVC or STATCOM • Harmonic filters • Passive and/or active • Advanced power electronic controllers • “Synthetic inertia” • Storage systems

8. Source : Alstom Off-shore Wind Farm (AC) On-shore sub-station AC Collector Platform Wind Turbines Submarine cable

9. Source : Siemens STATCOM Greater Gabbard off-shore wind farm, UK • Control of reactive power flow • Low voltage ride through • Harmonic distortion • System stability

10. HVDC Transmission i i i Idc Iac Iac t t t

11. Source : EirGrid East West Interconnector (EWIC) Eirgrid National Grid AC AC AC S/S AC S/S 45km 181km 34km DC DC Woodland Converter Station Shotton Converter Station ±200kV XLPE Cables

12. Source : EirGrid Woodland Converter Station Exterior view of converter station Interior view – converter hall

13. Ireland HVDC Schemes Existing Interconnectors Future interconnectors Embedded links

14. AC AC AC AC AC AC AC AC AC AC AC AC AC AC AC AC The Existing AC Grid 400 kV AC AC 110 kV 110 kV 10 kV 10 kV 10 kV 400 V 400 V 400 V

15. 320 kV DC AC Bulk power import using HVDC DC DC DC DC DC DC DC DC DC DC DC DC DC DC DC DC 150 kV 150 kV DC AC AC AC AC AC AC AC AC AC AC 50 kV 50 kV AC AC AC AC AC AC AC AC AC AC AC AC AC 10 kV 10 kV DC DC DC DC 500 V 500 V Electric Vehicle Charging Station Battery Energy Storage System Photo Voltaic Power Cells station The Grid of the Future? 400 kV AC AC Offshore wind farm DC DC 150 kV 150 kV 110 kV 110 kV 10 kV 35kV 10 kV 400 V 400 V 400 V

16. Conclusions • High levels of renewable generation can result in significant issues on the existing AC network • Smart grid solutions can be used to support and manage integration of renewable energy sources • Smart Grids = Power Electronics + Automation Systems

17. Any questions? TormoidMhicLeòid