GSP Group Correction Factors data from the Trading Operations Report


The page below details highlighted GSP Group Correction Factors (GGCFs) data from the previous month. This data is acquired from BSC Agents and inputted to the Trading Operation Monitoring Analysis System (TOMAS) database.

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Distribution of Half-Hour GGCFs across all GSP Groups

The chart bellow shows the distribution of GGCFs, as per the latest Settlement Run data, for each Settlement Period in the last complete season and the latest three complete years. Again it shows the effectiveness of profiling, with the ideal being a narrow distribution centred on 1.


The distribution of HH GSP GCFs, across all GSP Groups, for February 2024 remains similar to previous years with the percentage peak remaining close to 1; however, this month’s data remains slightly less skewed to the right when compared to the same month in previous years.

Half-Hour Correction factors by Settlement Period volume 

The following is based on Initial Settlement (SF) Run for the latest month and is weighted across all GSP Groups.

The chart below shows, for each of the day types used in profiling, a volume weighted average, such as adjusted to reflect the relative sizes of each GSP Group (in terms of total daily energy consumption), of the GGCFs across all GSP Groups by Settlement Period.

The source data are GGCFs from the Initial Settlement (SF) Run taken over the latest month for which SF data is available. The average is taken, for each Settlement Period, over the one month interval to create plots of volume-weighted GGCFs for the periods from Monday to Friday, for Saturdays and for Sundays included in the data set. It allows comparison of profiling for different day types and shows intra-day profiling effects.

Anything between 0.9 and 1.1 is considered reasonable. Values outside this range may indicate issues with load profiling or metering data.


The weighted GGCFs breakdowns show all GCFs across all day types (Monday to Friday, Saturday, and Sunday) remains within the expected tolerance except for Settlement Periods 34 to 40 where Sunday day types have seen above tolerance GGCFs.

Daily Average GSP Group Correction Factor by GSP Group

The chart below is based on the latest Settlement Run for the last two years.

This chart shows the daily average GGCF using the latest Settlement Run data for each GSP Group for the last two years. It shows both profiling and metering effects, as per the earlier explanation on the effects of profiling and metered volumes.


The daily average GCFs tend to remain between the higher and lower tolerances – with the largest peaks and troughs usually occurring around bank holidays.

Since June 2023, GCFs have been more volatile, with both the lower and upper thresholds breached on certain days. The low GCFs seen before in GSP Group _P in September/October which were likely caused by the known issue where metered data from a wind farm in this region is not received until later reconciliation runs, have now returned to the expected thresholds.

Zero GCFs for _N for some Settlement Periods (31 to 48) on 17 August 2023 at the R3 run which are the main cause of the low daily average GCF seen on the graph have been spotted and are being investigated.

The low GCFs seen in GSP_G on 16 September 2023 is under investigation and are expected to be corrected in the next settlement runs.


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