BC1

BC1 sets out the procedure for the submission of BMU data by BM partcipants, submission of system data by network operators and the provision of data by NGC in the period leading up to gate closure. It is inteded to enable NGC to assess expected BMU operation so that they can as far as possible maintain the integrity of the system and the security of supply.

• PNs- must be submitted by 11:00 for operational day ahead. If no submissions are made the PNs will default to the previous operational day's value. To ensure complaint we submit D+1 PNs for up to 4 days ahead when we conduct overnight scheduling of the coal, gas and nuclear assets.
• MEL data - submitted by 11:00 or it will default.
• Bid-Offer Data - submitted by 11:00 or it will default.
• Dynamic data - these should be submitted to amend data currently held by NGC. e.g. ramp rates, NDZ, MZT MNZT, SEL etc.
• "operational day" same as the gas day - 5am until 5am.
• Other relevant data - sent to NG by fax.

NGC will provide data to the Balancing Mechanism Reporting Agent (BMRA) (Elexon)

• Demand estimate - by 09:00 a forecast of national demand for operational day +1. By 12:00 a forecast of GB transmission system demand for each settlement period for the next operational day.
• Indidicated margin and imbalance - made available for each settlement period of the next operational day by 12:00.

Data will be updated throughout the day at various times.

Negative Reserve Active Power Margin (NRAPM) - how much flexible down generation have I got.

NGC will monitor total PNs against demand to see whether localised or system NRAPM is likely to be insuddicient. If NRAPM is likely to be insufficent, NGC will contact the relevant gensets to see if any change to the PN is possible.

NGC may need to identify special actions that need to be taken by specific users to maintain the integrity of the system. 

• Generator - post fault actions will generally involve a load change and the instruction will comply with previoulsy agree Special Action (an example would be a contract to intertrip a Heysham Unit) 
• External Interconnector operators: generally involve increase/decrease of interconnector power flows.

The arming and disarming of special actions is communicated to the shift teams by fax from NGC.