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

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 Hydro-electric Power

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

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 Solar Power

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 Renewable Energy Sources

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 The Issues

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 The Solutions

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

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

HVDC Transmission t i Iac t i t Idc i

East West Interconnector (EWIC) Source : EirGrid AC DC AC DC AC S/S Woodland Converter Station Shotton Converter Station 45km181km34km EirgridNational Grid ±200kV XLPE Cables

Woodland Converter Station Source : EirGrid Exterior view of converter stationInterior view – converter hall

Ireland HVDC Schemes Existing Interconnectors Future interconnectors Embedded links

The Existing AC Grid

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

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 Conclusions

Any questions? Tormoid Mhic Leòid