GBSQSS recommendation updates for offshore transmission networks

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GBSQSS recommendation up-dates foroffshore
transmission networks

• GBSQSS Sub Group
• OTEG 1st November 2006

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Contents

• Clarification notes
• Diversified versus non-diversified wind farm
  output
• Single and multiple wind farm connections
• Recommendation updates
• Further work plan
• Scope of Grid Code review
• Issues for OTEG consideration

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Clarification notes power output
Diversified
Non - Diversified
Individual wind turbines
Wind farm B
Wind farm A

• Assumes wind speed for single wind turbine
• Calculates turbine power output based on wind
• speed
• Calculates wind farm total output based upon
• single turbine output X turbines in the wind
  farm
• Wind farm spend more time at extremes
• i.e. maximum output and zero

• Assumes wind speed will never be uniform across
• the foot print of the wind farm
• Calculates turbine power output based on
  variable
• wind speed across area of wind farm
• Wind farm spends less time at extremes
• i.e. maximum output and zero

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Clarification notes

• Single and multiple wind farms single and
  multiple user connections

250MW user A Power station Y
250MW user A Power station X
250MW user B Power station Y
250MW user A Power station X
Multiple user connection
Single user connection
Local offshore platform
Single 500MW circuit
Single 450MW circuit
Shoreline
Onshore grid entry point
Onshore grid entry point
Figure 1 Connection of a single wind farm
Figure 2 connection of multiple wind farms
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Recommendation up-dates

• Specification of transformer platform capacity
  Installation of low voltage cable capacity as an
  option
• Clarification of single and multiple wind farm
  connections
• Further issues for sub-group and OTEG
  consideration

ownership of these LV cables requires
consideration
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Further work plan

• November
• Review of security for demand connections
• Review of security for generation with higher
  annual capacity factor
• Review of connection of generation to islands in
  Scotland
• Timescales to be advised
• Voltage limits for offshore transmission
• Feed into, if requested, Embedded Transmission
  discussions
• Feed into, if requested, Access Rights and
  Compensation discussions

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Scope of Grid Code Review (1)

• Modifications to the Grid Code and STC are
  required
• Relevant assumptions and conclusions made by the
  GBSQSS Sub-group will be taken into consideration
• Consideration will be given to the outcome of
  Embedded Transmission discussions

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Scope of Grid Code review (2)

• 1) Review Grid Code technical requirements on
  Generators wishing to connect to offshore
  Networks
• 2) Identify technical requirements on offshore
  TOs connecting to the onshore System.
• 3) Identify the consequential STC modifications
  that capture the GBSO /offshore TO interface

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Further issues for OTEG consideration

• Ownership of low voltage cables providing
  transmission capacity

500MW Offshore TS
Entry Point
500MW
Offshore TS Entry Point
Offshore Transmission circuits
Shoreline
Onshore substation (existing or new)
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Further issues for OTEG consideration

• Grid Code working group formation
• Option (a) Review GBSQSS sub-group membership and
  invite new members as appropriate
• Option (b) Formation of new Grid Code Sub-group
• GBSQSS sub-group recommendation extend
  invitation to GB Grid Code Review Panel members
• Terms of Reference for Grid Code sub-group
• Timescales and progress plan for Grid Code review
  work