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System Margin

About

The System Margin Summary chart provides more information about the margin between levels of generation and levels of availability in the market. This is most valuable in showing – when set to Offer Price and No Filter – the cost of margin in the market over time.

Within this chart it is possible to view the full timespan and then zoom in on activity of interest and this zooming can be used to show the following period in which margin went very expensive as the system tightened and as wind generation levels declined. During this particular period Balancing Mechanism prices peaked at £1,500/MWh:

Included Data

The data on this chart is the difference between the Max Export Limit availability (the maximum level at which the BM Unit may be exporting to the GB Transmission System at the Grid Supply Point) data and the Expected Metered Volume (post-balancing generation) when this difference is greater than zero. This is then aggregated across units in the market, with any data from interconnectors, nuclear or wind farms being excluded.

Data Service

The System Margin Summary data can be extracted from the API to get margin based upon a set of tags that can be extracted from the browser URL of the System Margin Summary chart during normal viewing. The parameters used as follows:

Code Required/Optional Description
chart Required systemmarginoverall
startdatetime Required The start date time in format YYYYMMDDHHMMSS.
enddatetime Required The end date time in format YYYYMMDDHHMMSS.
resolution Required The type of resolution. (See 'resolutions' action, e.g. hh)
series_to_plot Optional The groupings to break the margin down by, e.g. offerprice. This defaults to fuel and is as in the browser URL when picking options in the chart normally.
filter Optional The group to show data for, e.g. filter=fuel&fuel=coal. This defaults to no filter and is as in the browser URL when picking options in the chart normally.
format Required The type of format. The value could be xml or csv. (See 'formats' action)

Examples :

https://enbm.netareports.com/dataService?username=xxx&password=xxx&format=xml&action=data&chart=systemmarginoverall&startdatetime=20190520000000&enddatetime=20190527000000&resolution=hh&series_to_plot=offerprice&filter=fuel&fuel=coal