DN Operation

Iain Ward

DNCC Manager

Responsibilities

Licence Holder Obligation For 1 In 20 Capacity

DNCC Operates Networks Under Direction of The DN Winter / Summer Operating Strategy Booked Capacities Short Term Variations DN Specific Issues

DNCC Makes Within-Day Decisions Regarding Supply Demand Balancing Control of Unbilled Energy Plant Outage

Planned Unplanned (faults)

Daily Operations – Key Stages

Forecast Demand Define Diurnal Profile Programme Intakes Manage Demand Changes Respond to NTS Change Requests

Manage LDZ Take, Demand and Stock

Forecast Demand

LDZ Level Weather Data (NDM) VLDMC OPNs (DM) Approx 5% Demand Change per 1 deg C

Demands and Temperature Relationship

0 5 10 15 20 254

6

8

10

12

14

16

18

20

Temperatures

Dem

and

s

Demand

1ºC = 6%

1ºC = 3%

1ºC = 2%

Define Diurnal Profile

Diurnal Swing in the Range 12 – 15% Significance of Minimum Stock Time Storage Deficit in most DNs Storage Utilisation in Defined Order

DN Linepack DN LP Storage DN Bullets NTS Flow Variation

Diurnal Profiles

Supply Rate

1200 1800 2400 06000600

DemandProfile

B

C

AA

Storage Requirement

A + B - C

Empty Holders &Linepack,

FillHolders &Linepack

Manage LDZ Take, Demand and Stock

Programme Intakes

Remote Control of Offtake Utilisation Notifications to NTS via OPN Process Day Ahead and Within Day Considerations Meet Sub-LDZ Flow Requirements Pressure vs Volumetric Control Shrinkage Considerations Plant Outage Reflective of OCS Where Possible Request Additional Flow Flex via OPN Where

Necessary

Theddlethorpe Gas(38.2 - 38.7 MJ - m3)

Bacton Gas(38.2 - 38.6 MJ/m3)

St Fergus / Teesside Gas(39.2 - 41.5 MJ/m3)

St Fergus Gas(40 - 41.5 MJ/m3)

Easington/Rough Gas(38.1 - 38.7 MJ/m3)

St Fergus / Barrow Gas(38.4 - 41.5 MJ/m3)

CV Management

Manage Demand Changes

Forecast Updated 8 Times Daily (UNC timings) plus up to 5 ad-hoc.

Respond to Revised Weather Data Xmas period 2005; 5 degree error within day.

Rebalance DN Supply to Meet Demand Changes Revised Offtake Rates Impact on storage requirement Allocation to Volumetric Offtakes; balance effect of

pressure control?

Respond to NTS Change Requests

NTS To Anticipate Supply Rate Changes, Commercially and Physically Driven

NTS Outages Planned e.g. On-Line Inspection Un-Planned e.g. Faults

NTS VLDMC renominations

DNCC Offtake Performance

Booked Flat Capacity Limits Observed at DN Level Booked Flow Flex Limits Exceeded at LDZ Level

Some Offtakes on Some Days Pressure Controlled Flows Defined by Consumers

Within-day demand changes flow through into FlowFlex calculation.

LDZ 1

Flat and Flex Scatter at LDZ LevelOctober 2005 to Mid-Feb 2006

OCS Flat

OCS Flex

LDZ 2

Flat and Flex Scatter at LDZ Level October 2005 to Mid-Feb 2006

OCS Flat

OCS Flex