Figure of calculation process Gather 4-Second Data Types of input data There are four primary types of input data used to calculate Contribution Factors, described in clauses 4.1.2 to 4.1.5: 4-second active power measurement data; 4-second Frequency Indicator value; 5-minute demand forecasts and generating unit targets; and Contingency and data quality information. 4-second active power measurement data SCADA measurements of active power for appropriately metered generating units and are captured from the EMS. This represents the most recent data available at each loads 4-second sample. AEMO’s database application provides linear data interpolation in cases where the resolution of the SCADA data is larger than four-seconds, and in cases where interpolation is required across DI boundaries. 4-second Frequency Indicator value The Frequency Indicator (FI) represents the total Regulation FCAS requirement identified by AEMO’s AGC in a given 4-second period, and is sourced directly from AEMO’s AGC SCADA dataset. Contribution Factor calculations include an FI weighting component based on the significance of a given deviation, and its direction (whether it increases or decreases the need for Regulation FCAS). More information on the FI value calculation is provided in clause 5.2.4. 5-minute demand forecasts and generator targets Demand forecasts and dispatch instructions are both used to calculate reference trajectories, against the 4 second performance can be measured. Dispatch data is sourced directly from AEMO’s MMS. Frequency and data quality information Frequency measurements are sourced to identify the observed frequency. Any reported issues on data quality are considered in the identification of SCADA data requiring additional verification checks. If any of the required four-second SCADA data for a DI is determined on verification to be of corrupt or questionable quality, the data is corrected where possible by reloading from an alternative source, such as a duplicate server. More information on the exclusion of data is provided in clause 6.2.
Figure of calculation process Gather 4-Second Data Types of input data There are four primary types of input data used to calculate Contribution Factors, described in clauses 4.1.2 to 4.1.5: 4-second active power measurement data; 4-second Frequency Indicator value; 5-minute demand forecasts and generating unit targets; and Contingency and data quality information. 4-second active power measurement data SCADA measurements of active power for appropriately metered generating units and loads are captured from the EMS. This represents the most recent data available at each 4-second sample. AEMO’s database application provides linear data interpolation in cases where the resolution of the SCADA data is larger than four-seconds, and in cases where interpolation is required across DI boundaries. 4-second Frequency Indicator value The Frequency Indicator (FI) represents the total Regulation FCAS requirement identified by AEMO’s AGC in a given 4-second period, and is sourced directly from AEMO’s AGC SCADA dataset. Contribution Factor calculations include an FI weighting component based on the significance of a given deviation, and its direction (whether it increases or decreases the need for Regulation FCAS). More information on the FI value calculation is provided in clause 5.2.4. 5-minute demand forecasts and generator targets Demand forecasts and dispatch instructions are both used to calculate reference trajectories, against the 4 second performance can be measured. Dispatch data is sourced directly from AEMO’s MMS. Frequency and data quality information Frequency measurements are sourced to identify the observed frequency. Any reported issues on data quality are considered in the identification of SCADA data requiring additional verification checks. If any of the required four-second SCADA data for a DI is determined on verification to be of corrupt or questionable quality, the data is corrected where possible by reloading from an alternative source, such as a duplicate server. More information on the exclusion of data is provided in clause 6.2.