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OPNs. Offtake Arrangement Workstream – OAD Section I Review Group 316. OPNs - Agenda. OPN processes – walkthrough process flow diagrams of OAD section I/UNC section J DN inputs DN processes that feed into OPNs Operational constraints NTS Processes - PowerPoint PPT Presentation
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OPNs
Offtake Arrangement Workstream – OAD Section I Review Group 316
OPNs - Agenda
OPN processes – walkthrough process flow diagrams of OAD section I/UNC section J
DN inputs
DN processes that feed into OPNs
Operational constraints
NTS Processes
Overview of the NTS processes that currently feed off OPNs
NTS Manual work-arounds (including information on METGAS screen)
OPN accuracy
NTS Exit Reform (0195AV) Processes & NTS Risk Management tools - short preview of session 2 (November 2nd 2010)
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OPN Usage
Data Provision Definitions
Time by which theOfftake Profile
Notice for a Day isto be submitted to
National Grid(OAD I 2.21)
DNO may notsubmit any revisedprofiles after this
time 0400(OAD I 2.3.5 c)
End of Day DemandForecast Notice
Provided by the DNOuser in respect of the
NTS/LDZ Offtakes intoeach LDZ. Setting outthe aggregate forecast
LDZ Demand(UNC J 4.5.1 i)
18:0
0
22:0
0
02:0
0
06:0
0
10:0
0
14:0
0
18:0
0
22:0
0
02:0
0
06:0
0
14:0
0
Day - 1 Day
18:00
22:00
02:00
06:00
10:00
14:00
18:00
22:00
02:00
06:00
14:00
Day - 1 Day
End of Day DemandForecast Notice
Secured by the ShipperUser in respect of any otherrelevant System Exit Point.Setting out the estimatedtotal amount of gas to be
oftaken at that System ExitPoint during the Gas Day.
(UNC J 4.5.1 i)
Re-nomination Period
The DNO may not submit a Revised OPN:More frequently than once per hour;so as to change the rate of the offtake other than with effect from an exact hour of the clock later than 04:00 on the Gas day (OAD I 2.3.5)
The rates of the offtake set out in the OPN shall reflect as accurately as reasonably practicable The quantities, rates and times at which the DNO intends /expects to flow. (OAD I 2.1.5 a)
OPN Revision Requirements
Flow Rate Change >= 50% of the Maximum Flat Offtake Rate.(OAD I 2.3.1 a i)
Flow Rate Change is less than 50% but notless than 25% of the Maximum Flat Offtake
Rate(OAD I 2.3.1 a ii)
Flow Rate Change< 25% of the
Maximum FlatOfftake Rate.
(OAD I 2.3.1 a iii)
14:
00
15:
00
16:
00
17:
00
18:
00
IncreaseRate
Rate ChangeAll Flow Decreases
(OAD I 2.3.1 b)
DecreaseRate
If Revised OPN(s) impact the AggregateOfftake Rate for an LDZ then it/they shall besubmitted not less than 2hours before TROand the Aggregate Rate Change for the LDZ
shall be <=5%.(OAD I 2.3.3 a)
Time ofRate Change
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DN inputs
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Overview of the NTS processes that currently feed off OPNs
Key times in the current system process
Demand Forecaster Run Times:
Day-1• Calibration Runs• 13:00• 16:00• 24:00
Day• Every hour after 06:00
LDZ Take Data (Metgas Screen) and previous days OPNs used in GNCC processes due to OPN accuracy / timing issues.
HH:45Forecast data return
from Forecaster
HH:351. Effectors sent to Forecaster
2. Direct Connect OPNsentered into system.
35 2530
05550
40 20
105
45 15
HH:30Time limit for GNCC to
formally reject LDZ OPNvalues otherwise values
accepted by iGMS
HH:00Start time for
OPN ratechanges
HH:45 - HH:50LDZ OPN data entered
into iGMS inbox andvalidation checks run.
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NTS Manual Workarounds – METGAS
METGAS information
Forecast LDZ take provided by DNs via METGAS screens within GTMS
NTS ‘take’ = Demand Forecast + VLDMCs - (Interruption, LNG Boil Off, On Shore Fields) +/- Stock Change & Inter LDZ transfers
The METGAS screen provides a breakdown of the forecast NTS take, by LDZ and Total Take. It shows both within day and day ahead values and gives the time when the latest forecast was generated.
METGAS information (1) – Demand Forecast
NTS Demand Forecast:
An NTS Total system demand forecast comprises of data from all offtakes, i.e. direct connects, interconnector, LDZs, etc
LDZ NTS take
OPF process will substitute (last approved from previous day) OPN data that is not provided
METGAS information (2) – System balancing
National Grid NTS calculate Predicted Closing Line Pack (PCLP) and undertake balancing actions based on input and output information
Input Notifications from Delivery Facility Operators
Output Notifications provided to NTS by both Users (Direct Connects) & DNs respectively
For LDZ NTS take, NTS may use the following (depending on timing of PCLP calculation)
METGAS information
Offtake Profile Notifications
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OPN Accuracy & Timing
Offtake Tolerances
OAD Section I
3.1.2
The tolerance, in respect of the offtake of gas at an Offtake is 10% of the prevailing offtake rate
3.1.3
The tolerance, in respect of the offtake of gas in aggregate at all of the Offtakes which serve an LDZ, is 3% of the aggregate of the Prevailing Offtake Rates.
Proportion of OPNs breaching the 10% tolerance
Percentage of OPN Breaches by Zone
0% 10% 20% 30% 40% 50% 60%
A
B
C
D
E
F
G
H
I
J
K
L
M
Distribution of Forecast Error by LDZ
Distribution of % error by LDZ across all hour bars
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
60%
70%
A B C D E F G H I J K L M
80% Data Range P50 10% Tolerance
Distribution of Forecast Error by hour
Distribution of % error by hour bar for Interconnectors
-60%
-40%
-20%
0%
20%
40%
60%
06:0
0
07:0
0
08:0
0
09:0
0
10:0
0
11:0
0
12:0
0
13:0
0
14:0
0
15:0
0
16:0
0
17:0
0
18:0
0
19:0
0
20:0
0
21:0
0
22:0
0
23:0
0
00:0
0
01:0
0
02:0
0
03:0
0
04:0
0
05:0
0
80% Data Range
Distribution of % error by hour bar for Industrial offtakes
-60%
-40%
-20%
0%
20%
40%
60%
06:0
0
07:0
0
08:0
0
09:0
0
10:0
0
11:0
0
12:0
0
13:0
0
14:0
0
15:0
0
16:0
0
17:0
0
18:0
0
19:0
0
20:0
0
21:0
0
22:0
0
23:0
0
00:0
0
01:0
0
02:0
0
03:0
0
04:0
0
05:0
0
80% Data Range
Distribution of % error by hour bar for LDZ offtakes
-60%
-40%
-20%
0%
20%
40%
60%
06:0
0
07:0
0
08:0
0
09:0
0
10:0
0
11:0
0
12:0
0
13:0
0
14:0
0
15:0
0
16:0
0
17:0
0
18:0
0
19:0
0
20:0
0
21:0
0
22:0
0
23:0
0
00:0
0
01:0
0
02:0
0
03:0
0
04:0
0
05:0
0
80% Data Range
Distribution of % error by hour bar for Power Station offtakes
-60%
-40%
-20%
0%
20%
40%
60%
06:0
0
07:0
0
08:0
0
09:0
0
10:0
0
11:0
0
12:0
0
13:0
0
14:0
0
15:0
0
16:0
0
17:0
0
18:0
0
19:0
0
20:0
0
21:0
0
22:0
0
23:0
0
00:0
0
01:0
0
02:0
0
03:0
0
04:0
0
05:0
0
80% Data Range
Evolution of Forecast Error over time from sample offtakes
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
100%
D-1
13:
00
D-1
16:
00
D-1
18:
00
D-1
21:
00
D-1
23:
00
D-1
01:
00
D 1
0:00
D 1
3:00
D 1
6:00
D 1
8:00
D 2
1:00
D 2
3:00
D 0
1:00
D 0
5:00
80% Data Rangeth
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
100%
D-1
13:
00
D-1
16:
00
D-1
18:
00
D-1
21:
00
D-1
23:
00
D-1
01:
00
D 1
0:00
D 1
3:00
D 1
6:00
D 1
8:00
D 2
1:00
D 2
3:00
D 0
1:00
D 0
5:00
80% Data Range
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
100%
D-1
13:
00
D-1
16:
00
D-1
18:
00
D-1
21:
00
D-1
23:
00
D-1
01:
00
D 1
0:00
D 1
3:00
D 1
6:00
D 1
8:00
D 2
1:00
D 2
3:00
D 0
1:00
D 0
5:00
80% Data Range
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
100%
D-1
13:
00
D-1
16:
00
D-1
18:
00
D-1
21:
00
D-1
23:
00
D-1
01:
00
D 1
0:00
D 1
3:00
D 1
6:00
D 1
8:00
D 2
1:00
D 2
3:00
D 0
1:00
D 0
5:00
80% Data Range
Summary
Evidence provided that some OPNs are outside of the 10% offtake tolerance and the 3% LDZ tolerance
DN OPN processes run later than NTS demand forecast round up times?
Benefits associated with good quality OPNs (Current processes)
Continuous Improvement of Forecasting (Forecaster)
Enhanced Network Balancing
Physical Safe Operation of the NTS
Efficient Use of the NTS Delivery of Assured Pressures
Constraint management
Environmental Impact due to Compressor Usage Reduced Emissions
Less Venting
Better energy procurement
Lower Cost to the community
Commercial Efficient System Balancing Actions
Lower Cost to the Community
Better informs the Shippers balance position
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Preview of session 2 (November 2nd 2010)
NTS Exit Reform/Risk Management Processes
NTS Take -OPNs?
RegisteredExit
Capacity
NTS Risk Management
Flow Swap
Constraint Management
Real-timeNetworkModeling
tools
Overruns
