Mod_18_10 Intra Day Trading Conference Call Commercial Offer Data for Interconnector Units in Ending Overlap Optimisation Period (EOOP) for WD1 MSP Software Run 29 th November 2010

TW EA1 09:30EA2 11:30WD1 08:00 EA1 CODEA1 MIUNs fixed EA2 MIUNs + EA1 MIUNs fixed EA2 MIUNs fixed WD1 MIUNs + + LOW IMPORT PRICE HIGH IMPORT PRICE import EOOP SOOPTWEOOPTWEOOP OPTION 1 zero COD OPTION 2 EA2 COD OPTION 3 persist ? ? Scenario 1: Low to High Import Price NB No system change throughout the day to load/wind/gen availability/gen COD

TW EA1 09:30EA2 11:30WD1 08:00 EA1 CODEA1 MIUNs fixed EA2 MIUNs + EA1 MIUNs fixed EA2 MIUNs fixed WD1 MIUNs + + HIGH IMPORT PRICE LOW IMPORT PRICE import NB No system change throughout the day to load/wind/gen availability/gen COD EOOP SOOPTWEOOPTWEOOP OPTION 1 zero COD OPTION 2 EA2 COD OPTION 3 persist ? ? Scenario 2: High to Low Import Price

The optimisation for EOOP WD1 will influence the Interconnector flow for the last few hours of the relevant Trading Day (i.e. the end of the WD1 Trading Window). The outcome of the optimisation becomes the actual Interconnector flow. Any COD values used in the WD1 EOOP can only be a best estimate / guess, as bidding for these Trading Periods has not yet occurred. TSOs are concerned to minimise swings in Interconnector flow for bidding patterns that are not known. Such swings are likely to result in increases in constraint costs. Initial Considerations

If settlement optimisation outcomes (i.e. using actual bid values) are different from the dispatched values, this results in additional constraints. Once the WD1 schedule is produced, the Interconnector flow for the EOOP Trading Periods may be adjusted (if EA2 produces a lower flow than WD1, MIUNs will be adjusted in the previous Trading Day). Impacts on Constraints

For EA1/EA2, using the COD from the first 6 hours for the EOOP is a reasonable compromise. However, for WD1:  Using zero COD – is likely to produce an incorrect Interconnector schedule.  Using EA1/EA2 COD values from the start of the day – is very likely to be incorrect, as will not reflect price changes between EA2 and WD1 and may result in “artificial” swings in flow.  Persistence – reduces the likelihood of large “artificial” changes in the Interconnector flow at the end of the WD1 Trading Window. Options