BM Unit Operations

About

The BM Unit Operations chart is one of the most useful charts in the Historical Market Summary package as it shows the activity as a single or at a group of units in the market over time. This can be used to both see long-term behaviour at a unit or to see particular activity over a given day, week or month.

This includes the levels of availability and generation at a particular unit, along with a summary of the balancing volumes and prices that have been achieved.

This can for instance be seen for Eggborough unit 2 over time, showing how the unit has gone from baseload generation in early 2014, through an outage in summer 2014, through to mostly baseload operation in winter 2014/15, to another outage in summer 2015, to reduced operation in winter 2015/16 and then to only operating in the market via SBR in winter 2016/17.

It is then possible to zoom in on particular activity of interest:

Zooming in on this period, shows where the plant failed to meet planned levels of generation as it returned from its summer outage:

This chart is linked to from across this application and this by unit information forms the primary building blocks of the entire application.

Note on this chart that pressing up or down on the keyboard will cycle through the units included.

The series shown depend on the user’s permission levels as only users with permissions to see metered volume data will see this series.

Included Data

The data on this chart is as follows:

• Capacity - The nameplate capacity of the unit - ie if at 100% availability.
• Availability - Levels of real time availability as noted by Max Export Limit availability data (the maximum level at which the BM Unit may be exporting to the GB Transmission System at the Grid Supply Point), with units having an obligation to re-declare their Max Export Limit (MEL) whenever their availability reduces (for instance after a failed start). Where MEL is below expected metered volume a unit has an indicated imbalance.
• Import Availability - The Max Import Limit (MIL) which is the levels of declared import capability at units such as batteries or pumped storage.
• Stable Export Limit - The minimum stable export operating level for BM Unit, ie the point below which a unit cannot go without turning off.
• Stable Import Limit - The minimum stable import operating level for BM Unit, ie the point above which an importing unit cannot go without stopping importing or beginning export.
• Availability Forecast - The 2-14 Day Unit Output Usable OC2 availability data (the maximum expected daily availability). For wind farms this is a forecasted output value.
• Pre-Balancing Dispatch (FPN) - The levels of planned generation ahead of gate closure and typically matching the volumes sold in traded markets.
• Expected Metered Dispatch - The levels of post-balancing generation after National Grid has adjusted generation within gate closure.
• Metered Volume - On a 5-working-day behind basis users who have permissions that allow access to metered volume data will see operationally metered values that are a measurement of levels of generation recorded as being generation at a unit.
• Total Accepted Offer Volume - The total accepted offer volume is the total volume by which a unit has had its levels of generation increased via the Balancing Mechanism.
• Total Accepted Undo Offer Volume - The total accepted undo offer volume is the volume of offers that have been cancelled via an undo action, with this being a negative reduction in the offer.
• Total Accepted Bid Volume - The total accepted bid volume is the total volume by which a unit has had its levels of generation decreased via the Balancing Mechanism.
• Total Accepted Undo Bid Volume - The total accepted undo bid volume is the volume of bid that have been cancelled via an undo action, with this being a positive reduction in the bid.
• System Offer Volume - The system offer volume is the system flagged volume by which a unit has had its levels of generation increased via the Balancing Mechanism, ie the volume of actions issues for non-Energy reasons (e.g. due to a transmission constraint).
• System Bid Volume - The system bid volume is the system flagged volume by which a unit has had its levels of generation decreased via the Balancing Mechanism, ie the volume of actions issues for non-Energy reasons (e.g. due to a transmission constraint).
• Accepted Offer Price - The accepted offer price is the average price at which a unit has had its levels of generation increased via the Balancing Mechanism.
• Accepted Undo Offer Price - The accepted undo offer price is the average price at which a unit has had its offer volume cancelled via the Balancing Mechanism.
• Accepted Bid Price - The accepted bid price is the average price at which a unit has had its levels of generation decreased via the Balancing Mechanism.
• Accepted Undo Bid Price - The accepted undo bid price is the average price at which a unit has had its bid volume cancelled via the Balancing Mechanism.

On the Britned, French, Nemo and aggregate interconnector charts, the scheduled levels of imports are also indicated, which adds the following two series:

• Scheduled Imports DA - The nominated flows excluding within day trades.
• Scheduled Imports - The nominated flows including within day trades.

Data Service

The BM Unit Operations data can be extracted from the API to get the key unit operations data such as generation and Balancing Mechanism activity over time. The parameters used as follows: