Econnect LtdEconnect Ltd

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

Grid Connections: Lessons from Round One

Grid Connections: Lessons from Round One

Paul Glendinning

Operations Manager

Econnect Offshore Credentials

Econnect Offshore Credentials

• Designed 7 offshore wind farms

• Research for the DTI – Medium Voltage Systems for Offshore Windfarms

• Electrical Construction Management at North Hoyle

IntroductionIntroduction

• Onshore work for Offshore Projects

• Differences ?

• What are the issues ?

• Solutions

• Conclusions

Onshore work for Offshore Projects

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 ProgressNorth Hoyle Progress

• Onshore works

• Offshore / Onshore Interface

North Hoyle ProgressNorth Hoyle Progress

• Onshore works

• Cable Installation through the streets

North Hoyle ProgressNorth Hoyle Progress

• Onshore Works

• Careful management in public areas

North Hoyle ProgressNorth Hoyle Progress

• Onshore works

• Protection of cables in road

North Hoyle ProgressNorth Hoyle Progress

• Onshore works

• Careful route selection around a playing field

Differences ?Differences ?

• Electrical connection arrangements

• Radial versus Interconnected systems

• Cost of repairs – mobilisation of vessels

• Shore link cable environment

Differences ?Differences ?

• Repair and fault finding Crew ?

What are the issues ?What are the issues ?

• Switching, protection and Isolation

• Subsea cable fault repair

• Failure minimisation – maximise revenue

• Electrical losses

Solutions - Switching, Protection and IsolationSolutions - 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 IsolationSolutions - Switching,

Protection and Isolation

Wind Turbine 1 Wind Turbine 2 Wind Turbine 3 Wind Turbine 4 Wind Turbine 5

Fault Current Fault Current

Cable Fault

FPI FPI FPI FPI

Grid Connection

Solutions - Subsea cable fault repair

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

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

Solutions - Failure minimisation

• Layout at North Hoyle

Solutions - environmentSolutions - environment

• Equipment utilised must have a marinised specification

• Shore link cable requires careful analysis of burial depth and protection requirements – Geotechnical data required.

ConclusionsConclusions

• 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 LtdEconnect Ltd

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