New dataset on EMI – Constrained on/off costs and volumes

  • Last post 18 December 2018
Phil Bishop posted this 18 December 2018

A new data series - constrained on/off costs and volumes - has been published here.

A CSV file containing the dollar cost of constrained on/off payments by participant, location, trading period, and constraint type will be published each month. The series has been backfilled to June 2013. Megawatts and the implied price ($/MWh) are also provided.

This series expands and supersedes the series of costs due to the constraining on or off of frequency keeping previously published in the Ancillary services folder, by including costs arising from the constraining on or off of energy, reserves and dispatchable demand, as well as frequency keeping. Please note that the Ancillary services folder and all of its contents will soon be removed. See also this discussion.

The columns in the files of constrained on/off costs and volumes are:

  • Participant - a 4-letter code
  • ParticipantShortName
  • ConstraintType - Energy, Reserves, Dispatchable demand, and Frequency keeping
  • ProductType - Energy or Reserve
  • ProductClass - Injection or Offtake
  • ProductSubClass - FIR or SIR in the case of reserves, otherwise blank
  • ConstraintIndicator - On or Off, i.e. constrained on or constrained off. Note that reserves are only ever constrained on
  • TradingDate
  • TradingPeriod
  • PointOfConnection
  • OtherGridEntity
  • Unit
  • DollarsPerMegawattHour - implied from the Dollars and Megawatts, i.e. $/MWh = 2 * Dollars / Megawatt 
  • Megawatt
  • Dollars

Finally, be aware that the dollar values have been rounded to two decimal places when in fact the source data contained values to several decimal places. This rounding results in dollar values and prices of zero.

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NigelCByron posted this 18 December 2018

Phil - please advise when Access to the current Ancillary Services folder (particularly Constrained On/Off files) will be removed.

I must have missed that Constrained files were changing, along with Freq Keeping files (which we are deploying new file loaders for today 19Dec).

Bad timing to build a new loader and tables just before Xmas break !  End of January would be helpful.

Nigel Byron, Mercury

Phil Bishop posted this 18 December 2018

The Ancillary services folder and its contents can stay in place until 29 January 2019. The only items currently being updated in this folder are the files described here - please note that constrained on/off data published in the Ancillary services folder will not update between now and 29 January 2019.

The constrained on/off data published in the Ancillary services folder has been a manual and infrequent endeavour - usually only actioned when somebody requested we do so. The last update was in mid-November when five months' worth of data was uploaded at once. As noted above, the new dataset will be updated monthly, is a more complete set of data, and the publication process has been automated.