Ancillary Services Market Causer Pays Data
The recovery of payments for Regulation Services is based on the 'causer pays' methodology. Under this methodology, the response of measured generation and loads to frequency deviations is monitored and used to determine a series of causer pays factors.
There are three files that must be used in conjunction in order to interpret this data set.
Dynamic data files
The FCAS_*.csv file contains 4 second dynamic data. Each data set is published in a zipped file containing six 5 minute interval csv files.
There are 5 columns in each file containing:
- Timestamp, accurate to the second.
- Element number - relating to the items in the Elements Index file.
- Variable number - relating to the items listed in the Variables List file.
- Value - the actual dynamic value, normally expressed as a signed real.
- Value quality - there are 3 options: 0 = good quality, -1 = not applicable, +1 = bad quality.
Elements Index file
This file contains a list of the static plant names (generators, loads, interconnectors) and static names of special measurements (system frequency, AreaControlError, time error).
Each plant name/special measurement has a unique number associate with it in the FCAS_*.csv file (see Column B). This number is used in the Elements Index list of all plant names and special measurement names (Column A). Column B of the Elements Index lists the actual names.
This file is only updated when a plant item is introduced to or removed from the grid, and will therefore be revised on an ad hoc basis.
This file has been updated to include:
Musselroe WF (271)
Effective date 11 March 2013.
Variables List file
The Variables List file contains a list of the measurement "variable" measurement types.
Column C in the FCAS_*.csv file relates back to the number of each variable on the Variables List in order to identify the relevant measurement type of the data in the dynamic data file.
The broad measurement types are:
- Power (MW)
- System Frequency (Hz)
- Electrical Time Error (Seconds)
- Area Control Error (Calculated out of AGC as a MW excess or deficiency)
- Regulation Participation Factor (%)
- Modes of operation (eg.AGC ON, or AGC OFF)
Column B of the Variables List contains acronyms for the variables, and are briefly defined as follows:
MW MW typically for Interconnectors and Loads.
Gen_MW MW used to distinguish Generator output.
GenSPD_MW MW as the Generator SPD 5-minute basepoint (fixed) dispatch target.
GenRegComp_MW MW expressed for the individual Generator Regulation Component.
SPD_MWB MW as the Generator or Interconnector SPD basepoint target. This is effectively identical to Gen_MW or MW but is obtained directly from SPD and not via the AGC. These devices are not usually dispatchable.
GenRPF_% Regulation Participation factor (%) per Generator. The aggregate of all generators providing frequency regulation should always make 100%. The RPF is a measure of how much regulation (MW) is available.
ON Something that is "ON". It is only ON if the associated Value is not zero. This term is used to identify if AGC is active at the monitored site.
OFF Something that is marked OFF if the associated Value is non-zero. This type is not yet used.
ACE Used for the AGC calculated AreaControlError. The sign of the ACE defines if there is a MW deficiency (-ve) or MW excess (+ve).
ACEFIL A (low-pass) filtered ACE. The ACE is very dynamic and the filtered ACE gives a better representation of which way the ACE is going.
ACEINT The integral of ACE over a defined time period (one hour) and is expressed as a MWH.
HZ Used for System frequency measurements and represents the same frequency that AGC uses.
HZNOM Usually the nominal frequency is 50.00000Hz but the AGC may be directed to consider a different nominal frequency for a brief period, usually subsequent to a major disturbance to hasten any time related errors.
HZOFFSET Is used to express the frequency error (the difference between HZ and HZNOM).
HZDEV Derived from HZOFFSET as a measure of deviation .
SEC Used to express (electrical) time errors. The unit is in seconds and is a measure of the difference between electrical time and standard time.
These data sets are provided subject to this Disclaimer.