review group 316 – review of section i of the offtake arrangements document (oad)
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Review Group 316 – Review of Section I of the Offtake Arrangements Document (OAD). Offtake Arrangements Workstream – 8 th December 2010. Contents. Actions from previous meeting Rules around OPN rejections Flow Swaps update Difficult Day scenarios OPN Options Pressures - PowerPoint PPT PresentationTRANSCRIPT
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Review Group 316 – Review of Section I of the Offtake Arrangements Document (OAD)
Offtake Arrangements Workstream – 8th December 2010
Contents
Actions from previous meeting
Rules around OPN rejections
Flow Swaps update
Difficult Day scenarios
OPN Options
Pressures
Potential RIIO Impacts on OAD – Pressures and OPN process
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Rules around OPN rejections
Rules around OPN rejections
Note: further rejection reasons will be added as part of the enduring exit regime
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Review Group 316 – Flow Swaps update
Mike Wassell
Background
National Grid NTS and the DNOs may initiate flow swaps to manage their systems economically and efficiently.
From the 1st of Oct 2012 DNO User(s) are subject to NTS Exit (flat) Capacity overrun charges and any resulting deemed enduring applications.
Overview provided at last workshop to discuss Flow Swaps and a potential solution to swap capacity was briefly discussed to address this issue.
Potential High level Solution – views sought
Aim
For a National Grid NTS Initiated Flow Swap to not impact upon a DN Flat Overrun position in the enduring regime
How?
Transfer a quantity of Firm NTS Exit (Flat) Capacity entitlement from the reducing Exit Point to the Increasing Exit Point that, where possible, is equivalent to the National Grid NTS requested (and subsequently agreed) offtake flow rate changes.
The equivalent Firm NTS Exit (flat) capacity entitlement swap is calculated based on the requested duration of the Flow swap and the offtake flow rate changes requested.
E.g. 500,000 kWh/day flow rate request from offtake A to offtake B effective from 18.00 until the end of day.
Firm NTS Exit (Flat) Capacity swap would be 500,000 / 24 * 12 = 250,000 kWh/day equivalent of Firm Capacity
Potential High level Solution – views sought
Capacity swap occurs upon agreement of flow swap
DNO be able to view / notified of revised entitlements post agreement
Potential recording / approval via Gemini System
To avoid CV conversion issues, flow swaps could be requested in energy
Potential High level Solution – views sought
If calculated capacity entitlement swap is greater than capacity held by DNO User at reducing offtake, then the maximum possible firm capacity will be transferred across however will not cause the overrun position to be any worst
Example - NTS request flow swap of 4 Units of NTS (Flat) Capacity Entitlement from Exit Point A to Exit point B
A B
Pre Flow Swap Flow 4 Flow 4
Capacity 3 Capacity 4
A B
Post Flow SwapFlow 0 Flow 8
Capacity 0 Capacity 7
Example of Flow Swap
Exit Point A Exit Point B
Flow 10 Flow 0
Capacity 10 Capacity 5
National Grid request a Flow Swap from NTS/LDZ offtake A to NTS/ LDZ offtake B of 7
Post Flow Swap
Exit Point A Exit Point B
Flow 3 Flow 7
Capacity 10 Capacity 5
Pre Flow Swap
Possible Solution
Equivalent capacity of the flow swap to be transferred from exit Point A to Exit Point B hence a reduction of 7 at A and an increase of 7 at B
3
Capacity 12
7Exit Point A Exit Point B
Capacity 3
Flow 7Flow 3
Next steps
Refine potential solution?
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Difficult Day Scenarios
Mark Amos
Difficult Days
Transitional & Enduring processes comparison
Real day scenario
Constraint Management tools timing
Issues with inaccurate D1 forecasts
Difficult Days: CM Processes
StepExisting (Transitional)
Constraint Management Process
Future (Enduring) Constraint Management Process
These processes are in addition to the existing transitional processes and GNCC monitoring shall continue as is.
1GNCC continually monitor zonal linepack and critical
offtake pressures.
OPN & DFN data is analysed along with the current telemetered state of the NTS from D-1 onwards
using the online network simulation model.
Continually reanalyse online network model as updated OPN/DFN data is submitted by Users.
2Concern is raised as the levels of linepack/pressure in
an area of the network are rapidly decreasing.
Online Network Analysis indicates a potential exit constraint. Model outputs the predicted
magnitude, timing and location of the constraint.3
Extrapolating the linepack/pressure movement forwards supported by operator judgement gives
cause for concern that minimum obligations/network requirements may be
breached.
4NTS configuration is optimised to maximise the capability and increase linepack/pressures in the area
where the potential constraint is identified.
5Linepack/pressure monitored during/after network
optimisation.Online Network Simulation continues to evaluate the
predicted state of the network.
6Further concern is raised that the reconfiguration will
not avoid the constraint. Constraint forecast to be reached in x hours.
Online Network Analysis indicates a potential exit constraint still exists. Model outputs the
magnitude and location of the constraint.
Difficult Days: CM Processes cont.
Step Existing (Transitional) ProcessFuture (Enduring) Process
These processes are in addition to the existing transitional processes and GNCC monitoring shall continue as is.
7
Constraint Management Procedures Initiated
Consider potential actions to take to avoid the constraint:
Cost analysis of the following options undertaken to highlight the most cost-effective tools to use in order
to avoid the constraint:
Day-ahead Options (D-1):
OPN Checking & Rejection
Low Demand Days
Constrained Storage Usage
SFRN (System Flexibility Restriction Notice (Can notify within day also)
Restricting within-day Firm Capacity Release (08:00 clearing auction restriction, identified @ EOD D-1).
Within-day Options (D):
OPN Revisions Checking & Rejection
Flow-Swapping
Locational Energy Buy Action
Operating Margins
Interruption
Off-Peak Capacity Management (Can initiate @ D-1)
Exit Capacity Surrender Auction (Can initiate @ D-1)
Constraint Management Agreements (Can initiate @ D-1)
Offtake Reduction Invitations (Can initiate @ D-1)
Difficult Days: CM Processes cont.
Step Existing (Transitional) ProcessFuture (Enduring) Process
These processes are in addition to the existing transitional processes and GNCC monitoring shall continue as is.
8 Constraint management actions taken.Constraint Management Options evaluated and
Users notified/requested to submit bids where necessary.
9Monitoring continues to confirm actions taken will
avoid the constraint. Further actions may be necessary.
Offers received from Users and simple cost analysis undertaken to confirm least cost solution for the
community. Bids accepted/Users notified.
Where time permits, on-line analysis is used to confirm the most efficient constraint
management option in terms of flow change and location.
Difficult Day: Real Data
0
2
4
6
8
10
12
14
16
18
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0Hour Bars
Agg
rega
te D
N O
ffta
ke F
low
(m
cm)
0
0.2
0.4
0.6
0.8
1
1.2
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0
Hour Bars
LD
Z F
low
(m
cm
)
0
0.2
0.4
0.6
0.8
1
1.2
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0
Hour Bars
LD
Z F
low
(m
cm)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0
Hour Bars
LD
Z F
low
(m
cm
)
Aggregate, All DNOs
LDZ 01
LDZ 02 LDZ 03
= Actual Flow
= OPN
Within-day CM Tools Timeline
Forecast Constraint Start Time
4Off-Peak Scaleback: Min 4 hrs notice
2Offtake Flow Reduction: Min 2 hrs notice following invitation/allocation 1
1Locational Buy Action: Time required to Request / Accept / Re-nominate
11Surrender (Buyback): Hour bar + 1 notice following bid acceptance
11Options Contract Exercise: Hour bar + 1 notice following bid acceptance
1Flow Swaps: User driven, possibility of action within 1 hour, potentially greater
4Ops Margins: 6hrs notice for standby, 2hrs LNG otherwise
DRestricting Within-day Firm: Constraint forecast prior to 08:00 capacity auction
1
2
1Constrained Storage: Min 1hr following revised demand forecast
Potential Outcome of Inaccurate D-1 Forecast
Constraint is not forecast and within-day Firm Capacity remains unrestricted, potentially exacerbating any constraint management costs (buybacks)
SFRN not issued, with the potential that further flexibility capacity is released within-day
The more time available to deal with a constraint (i.e. the earlier the forecast), the lower the cost associated with dealing with the constraint and the higher the liklihood the constraint will be avoided:
Issue notifications/invitations to Users early
Give Users more time to evaluate their turn-down/up options
More time to evaluate multiple options in GNCC
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Pressures
Glenn Bryn-Jacobsen
0600 Pressure Process
Concept of 0600 pressure is based upon providing the maximum amount of linepack to the downstream system at the start of the gas day
OAD Section I seeks to establish a process to operationally manage the real time practical pressures for transporters to meet the obligation of being economic, safe and efficient. On days other than a 1 in 20 day an LDZ may not require the assured pressure – this forms the basis for an agreed pressure
Timing of the process / agreed pressures may impact OPN submission
Agreed pressure is not revised
after the 2300 process
NTS will contact DNO if an issue occurs which will cause significant
deviance from agreed pressure (e.g. if experiencing issues with
system)
Potential impact on OPN submission
Agreed pressures process based upon ‘critical list’ of key offtakes for each DNO
D-1 0600 pressure assessed for key offtakes by 2300
Operational discussions as
required
Revised OPN submissions
23002300 24002400
If DNO request a different pressure
which can be provided then the
agreed pressure will be revised
NTS conditions (e.g. terminal/storage behaviour) may
vary from operational assumptions leading to actual 0600 pressure differing from agreed pressures
NTS may also advise DNO if significant occurrence on the NTS will affect offtakes which are not included on
the agreed list
(DNO may contact NTS Gas Operations to review
‘critical list’)
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OPN Options
Mark Amos
OPN Options – “What is the problem?”
OPN Accuracy
Wish to maintain accuracy measure (tolerances) against prevailing OPNs
Current tolerances seem inappropriate
What can we do to improve accuracy?
Invest to ensure all OPNs are provided accurately?
Manage current resource to focus on improving accuracy for key offtakes?
Remove storage booking/risk from OPNs?
OPN Timing
Ensure OPNs provide sufficient warning of flow changes
Ensure NTS system takes into account OPNs provided in a timely manner
NTS Preferred Option
Make improvements to meet current OAD obligations & improve accuracy of OPNs that will feed into Enduring Exit Regime processes
Advantages
Maintains current obligations for provision of offtake info to NTS
Supports Enduring Exit constraint management tools
Minimises Constraint Management Costs for Community
Increased System Operator efficiency in other NTS processes through more accurate within-day modelling
Disadvantages
Costs? Practicality? Resources?
Discuss: How to achieve preferred option?
Can the NTS preferred option be achieved?
What are the potential blockers?
What prevents accuracy?
How to separate short term flexibility capacity booking from flow profile notification forecasts?
Issues related to pressure controlled offtakes?
Possible drivers for improvements
Additional info from NTS?
Incentives?
Charges?
Alternative options
Alternative options that could be explored;
Focus on key offtakes – may be some merit?
Aggregate at LDZ / Flex zones – not recommended by NTS
National Grid is happy to work with DNOs to explore cost / benefit analysis of alternative approaches
Provide accurate OPNs for key Offtakes?
Rather than providing OPNs for all offtakes irrespective of the size / criticality to system, focus scarce DN resources on ensuring accurate & timely OPNs are provided for key offtakes
Change OAD to enhance existing rules for key offtakes
Options include;
Volume based process i.e. accurate OPNs submitted for larger sites i.e. > x mcm/hour
Accurate OPNs are provided for a ‘critical’ list of x sites agreed by NTS & DNs against set criteria
Appropriate tolerances would need to be set for all key and less key offtakes
Next Steps
DNs to provide an understanding of forecasting processes
DNs to provide details regarding what the issues are that prevent accuracy
DNs to deliver preferred options with pros/cons
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Potential RIIO Impacts on OAD Section I – Pressures & OPN processes
Chris Shanley
Ofgem Capacity Working Group meeting held on 11th November
Ofgem want DNs and NTS to share information in order to deliver investment for capacity in Networks in the most efficient way across the NTS/DN interface
Ofgem are looking to develop output measures, indicators and uncertainty mechanisms to achieve this
To achieve an efficient investment outcome between the NTS and the DNs a number of factors may need to be considered:
NTS/DN investment
Diurnal Storage provision
DN interruption
Fit for purpose Capacity and Pressure processes
The interaction between capacity, flexibility and pressures
Other changes, i.e. UNC, Charges, etc.
Next Steps
Ofgem to produce initial strategy document in Dec 2010
Strategy Decision document in March 2011
Uncertain at this stage as to what the knock on changes to the UNC will be.
Where does this leave the OAD Section I Review?