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Agency Models Transmission Arrangements for Distributed Generation - - PowerPoint PPT Presentation
Agency Models Transmission Arrangements for Distributed Generation - - PowerPoint PPT Presentation
Agency Models Transmission Arrangements for Distributed Generation London: 14 July 2006 Structure The Problem (National Grid perspective) Agency Model Options Three Strawmen for discussion The Problems Cost reflectivity of
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The Problems
Cost reflectivity of transmission charges falls as unlicensed
embedded generation increases
- All generation has an effect on transmission flows
- Not just about exporting GSPs
Governance framework does not recognise flow from
distribution to transmission without a BEGA
- No access product
No operational control where transmission affected
- DNO networks effectively becoming active
Investment planning and locational signals
- Embedded Generation growth
Specific issues in Scotland
More than just a charging issue, only agency models can resolve
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What do we mean by “Agency”?
Single point of contact/ interface Aggregator of capacity and energy Controller of despatch Who? Options: “GBSO” to extend into DNO networks? 14 DNOs to become “active” – DNO Agency Use Supplier interface – Supplier Agency
X
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Key Considerations
Gross v Net
Should embedded generation net from demand?
- Transmission Charges based on “spill” or installed capacity?
Appropriate threshold?
Nodes v Zones
Would a defined transmission access product be nodal
- r zonal?
The degree of change
What are we assuming the agent will do?
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Agency Model Matrix
Gross of Gross of Net of Net of GSP GSP Group GSP GSP Group
Supplier Agency DNO Agency
“TODAY” (sort of)
Very Difficult, SVA at GSP Group level, Would need to Re-register 23m meters Nodal Model Superior Nodal Model Superior “Interconnector model” Possible, but involves a lot
- f change
Strawman 3 Strawman 2 Strawman 1
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Why these Strawmen - objectives
“Gross” for cost reflective charging “Nodal” (where pragmatic) for operational control Supplier agent for least change, but DNO Agent
could work if it was fully active
We think DNO Agent is a lot of change
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Supplier v DNO Agent
- Association of bids/ offers with nodes
- How does DNO resolve constraints and
actively manage the system? – does it need to?
- SO despatching plant on another system –
safety/ security/ MVar
- SO would be issuing BOAs via Supplier
Agency
- Major industry restructuring
- 14 control rooms
- DNO trading energy?
- How BM interaction managed?
- Methodology to pass transmission
charges to suppliers
- Treatment of large embedded
- Reform of exit product
- If “net” model, max export to Grid not at
system peak
- Definition of service – response/
reactive Cons
- Uses existing settlement structure
- Efficient charging signals
- Could be implemented in short term
- Simple conceptually
- Physical alignment
- Clear operational boundaries of
responsibility
- DNO bids and offers on a nodal basis
Pros
Supplier Agency DNO Agency
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Gross Zonal Supplier Agency Model (GZSAM)
- Introduction to Strawman 1
GSP GSP GSP GROUP EG D D EG Distribution Network Transmission Network
NHHd2 HHd1 HHg1 HHg2 NHHd1 HHg2
M1 M2 Today GZSAM ∑HHd - ∑HHg
Netted off + ∑NHHd
HH £/kW Zonal Dem Tariff NHH p/kWh Zonal Dem Tariff
∑HHd
+ ∑NHHd
HH £/kW Zonal Dem Tariff NHH p/kWh Zonal Dem Tariff
For a Supplier, In the BM, aggregated zonal embedded generation might be offered to the SO in a single “sub-BMU”
HHg1 + HHg2
£/kW Gen TNUoS Tariff
Generation BMU
Demand
Generation BMU +
Generation
£/kW Gen TNUoS Tariff £/kW Gen TNUoS Tariff
zTEC
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National Grid DC Gen DNO National Grid DC Gen DNO SVA LEEG BEGA CVA LEEG
TEC Operational interface TEC Sum of Export capability
National Grid DC Gen DNO National Grid DC Gen DNO SVA LEEG BEGA CVA LEEG
TEC TEC Suppliers (negative demand)
Gross Nodal DNO Agent Model (GNDAM)
- Introduction to Strawman 2
TODAY GDAM
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Gross Nodal Supplier Agency Model (GNSAM)
- Introduction to Strawman 3
GSP GSP GSP GROUP EG D D EG Distribution Network Transmission Network
NHHd2 HHd1 HHg1 HHg2 NHHd1 HHg2
M1 M2 Today GNSAM
Netted off
HH £/kW Zonal Dem Tariff NHH p/kWh Zonal Dem Tariff
∑HHd
+ ∑NHHd
HH £/kW Zonal Dem Tariff NHH p/kWh Zonal Dem Tariff
For a Supplier, Each embedded generator above a given threshold might be offered to the SO as a single BMU
HHg1
£/kW Gen TNUoS Tariff
Generation BMU
Demand
Generation BMU +
Generation
£/kW Gen TNUoS Tariff £/kW Gen TNUoS Tariff
TEC
HHg2
£/kW Gen TNUoS Tariff
+
TEC ∑HHd - ∑HHg+ ∑NHHd
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Summary
There are different approaches None of the agency models are simple We think “gross” and “nodal” are important
- cf. “net” and “zonal” today
No preference which agent DNO conceptually simpler Supplier least change
Other Agency ideas?
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The Problem - National Grid Perspective
- “Gross” Background
All generation has an effect on transmission flows
Power flow south EG within +ve generation TNUoS charging zones can reduce local demand, but may increase flows south Transmission constraint
GSPs do not have to be exporting to affect transmission
Similarly, EG within negative generation TNUoS charging zones may reduce flows south
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Impact is the same as transmission connected 10MW EG 10MW D D G G
Impact of Embedded Generation
- “Gross” Background