Imbalances Heatmap

About

The Imbalances Heatmap plots over a period of time the levels of imbalance as a percentage of installed capacity at a particular filter grouping (or for the two market) on a by unit level over time. Each of the cells in this heatmap include a link that can be clicked on to go through to the BM Unit Operations chart.

The tool uses as its smallest resolution half-hourly data so levels of imbalance may not be accurate on a minute-to-minute basis and will not pick up on imbalances lasting on a few minutes, but should the MEL remain at 0 for the next few half-hourly settlement periods while the unit solves its problems an imbalance will be noted.

Once a time period has been set the chart will then display data across the time zone at the highest resolution to show all the data on the screen with only vertical scrolling. For instance a screen might show a week’s data at 6 hour resolution, but a wide screen might show the same data at 3 hour resolution.

Additionally it is possible to filter out any entries that contain no values by filtering for either all units or for only units with data in this period. In this instance this will remove any units that had no imbalances noted across the whole period.

Included Data

The data on this chart is as follows:

• Capacity - The nameplate capacity of the unit - ie if at 100% availability.
• Max Imbalance - The highest imbalance level that occurred in the period.
• Av Imbalance Size - The average size of imbalance levels when they were non-zero in the period.
• Imbalance - The average level of imbalance in the period (being reduced by zero values when imbalances were not occurring).
• Trip Frequency - The frequency of periods of imbalance (counting 1 as a period from imbalance volume being >0 until the period when the imbalance volume returns to zero.
• Start Trip Frequency - As with the Trip Frequency, but only recording trips when a start has also occurred in the period up to 3 hours before the trip begins.

The imbalance volume is calculated as the maximum of zero and the generation subtracting the availability, ie the levels of generation that cannot be achieved because of insufficient availability.

The availability figure used is the 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).

The generation figure used is the levels of post-balancing generation after National Grid has adjusted generation within gate closure.

Colours Guide

The following details the colours used in this chart:

Data Service

The Imbalances Heatmap data can be extracted from the API to extract the level of imbalances (availability below expected generation) as a percentage of capacity across all the listed units over time. The parameters used as follows: