Econnect Ltd Independent specialists in the grid integration of renewable energy...

Grid Connections: Lessons from Round One Paul Glendinning Operations Manager

Econnect Offshore Credentials Designed 7 offshore wind farms Research for the DTI – Medium Voltage Systems for Offshore Windfarms Electrical Construction Management at North Hoyle

Introduction Onshore work for Offshore Projects Differences ? What are the issues ? Solutions Conclusions

Onshore work for Offshore Projects Substation connections Either at 132kV or 33kV for the 30 to 60 turbine wind farms Cable connections Onshore Cable interconnection facility

North Hoyle Progress Onshore works Offshore / Onshore Interface

North Hoyle Progress Onshore works Cable Installation through the streets

North Hoyle Progress Onshore Works Careful management in public areas

North Hoyle Progress Onshore works Protection of cables in road

North Hoyle Progress Onshore works Careful route selection around a playing field

Differences ? Electrical connection arrangements Radial versus Interconnected systems Cost of repairs – mobilisation of vessels Shore link cable environment

Differences ? Repair and fault finding Crew ?

What are the issues ? Switching, protection and Isolation Subsea cable fault repair Failure minimisation – maximise revenue Electrical losses

Solutions - Switching, Protection and Isolation Increasing degrees of automation required Use of motorised ring switches Use of Fault Passage Indicators Reduce visits to farm Avoid personnel transfer to turbines

Solutions - Switching, Protection and Isolation

Solutions - Subsea cable fault repair Use of Time Domain Reflectometers or search coil Cable on shore link may be tens of meters away from original burial position Burial methods require careful analysis

Solutions - Failure minimisation Cost of single cable fault in 60 MW wind farm is £650K Use of standby power from Offshore diesel equipment Use of interconnected electrical systems

Solutions - Failure minimisation Layout at North Hoyle

Solutions - environment Equipment utilised must have a marinised specification Shore link cable requires careful analysis of burial depth and protection requirements – Geotechnical data required.

Conclusions Onshore electrical arrangements – not valid The protection of the shore link cable is critical compared to inter-link cables Equipment utilised must be marinised Invest in cable specification and installation protection Invest in Electrical topology

Econnect Ltd Independent specialists in the grid integration of renewable energy...