Intermittent Generator Availability

About Intermittent Generator availability

The Intermittent Generation - Availability interfaces allow participants’ operational staff to submit availability information on both a farm-wide basis (as a unit Upper MW Limit MW Limit restriction, indicating when a facility is down regulated. An MW limit is applied in the Unit’s control system to limit its MW output to below maximum capacity.) and an individual Cluster A cluster is a group of intermittent generating units; there may be more than one cluster in a Unit. AEMO may agree to have non-identical turbines in a cluster in exceptional circumstances. element basis (as Cluster Elements Available). This refers to the unit's technical availability in PD Pre-dispatch/STPASA Short-term Projected Assessment of System Adequacy. 30 minute resolution, seven days ahead. A daily load forecast showing expected demand two to seven days ahead of time. and MT PASA Medium Term Projected Assessment of System Adequacy. A 24-month supply demand forecast, published weekly, with daily resolution..

A Cluster is a group of intermittent generating units. A Unit A Scheduled, Semi-Scheduled, or Non-Scheduled Generating Unit comprises one or more Clusters.

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In this guide, the availability of an intermittent generating unit refers to its plant availability over the relevant period. The Rules The National Gas or Electricity rules. require a Semi-Scheduled Generator to submit plant availability for its semi-scheduled generating unit. The Rules also allow AEMO Australian Energy Market Operator to require a Non-Scheduled Generator to submit plant availability for its non-scheduled generating unit, if deemed significant for forecasting purposes.

The Rules define plant availability as:

The active power capability of a generating unit (in MW), based on the availability of its electrical power conversion process and assuming no fuel supply limitations on the energy available for input to that electrical power conversion process.

Participants with Intermittent Generation can manage their commercial availability by updating the Maximum Availability The maximum planned availability in MW for the matching period. (Max Avail) in their Energy Offer The unit must be a generator for the service type, Energy.. The availability used in Dispatch See National Electricity Rules, 5min PD, PD and PASA is the minimum of the UIGF Unconstrained Intermittent Generation Forecast. A forecast of available capacity for wind and solar generating units for the period five minutes to two years ahead. and Max Avail.

Availability = min (UIGF, Max Avail)
Where UIGF is:
- UIGF50 for NEMDE NEM Dispatch Engine (previously SPD). Software developed and used by AEMO to ensure the central dispatch process maximises value of trade, subject to the various constraints. processes (DS Dispatch, 5MPD 5-minute Pre-dispatch, PD)
- UIGF50 or UIGF90 for PASA processes, depending on the Run Type
Max Avail is the Energy The unit must be a generator for the service type: ‘energy’. Loads cannot bid for mandatory restrictions capacity. Maximum Availability Bid See Relevant Rules or Procedures in the Dispatch Offer Energy, Dispatch, FCAS Offer, MNSP, MTPASA Bid or Offer submission.

Effective upper limit

Unit forecasts are capped at the Effective Upper Limit Intermittent Generation term, which is:

Where:

n = Cluster within unit

c = total number of clusters within unit

Elements available

Elements Available are also used to scale down the full availability forecast.

For MT PASA forecasts, participants submit this availability information on a daily peak basis using the MT PASA Availability interface. Availability information can be submitted for any day in the future, even if beyond the MT PASA forecast horizon.

For predispatch and STPASA forecasts, participants submit this availability information on a 30-minute interval basis over the next eight days using the PD/STPASA Availability interface. Availability information can be submitted for any interval in the future, even if beyond the PD/STPASA forecast horizon.

For dispatch and the 5-minute predispatch forecasts, the availability information submitted using the Intermittent Generation – Availability interface does not apply.

The availability information submitted in the Intermittent Generation – Availability interface does not affect the dispatch and the 5-minute predispatch forecasts. Participants must ensure the current availability (as reflected in the SCADA Local Limit Same as upper MW limit. and SCADA Supervisory Control and Data Acquisition. A system that gathers real-time data from remote terminal units and other communication sources in the field and enables operators to control field devices from their consoles. Turbines/Inverters Available) is consistent with the availability submitted in the Intermittent Generation – Availability interface for the current interval.

Local limitations

In the dispatch and 5-minute predispatch forecast time frames, the participant must manage farm-wide local limitations and element availability information by submitting a real-time SCADA Local Limit and a SCADA Turbines Available signal (for wind) or SCADA Inverters Available signal (for solar). If these signals do not reflect the actual availability or are unavailable, participants can update their energy bid (through Max Avail) to achieve the desired dispatch outcome.

As a last resort, participants can request the AEMO Control Room to apply a quick constraint to the actual MW availability level if the ECM Energy Conversion Model for Wind and Solar SCADA signals fail to reflect the farm's true availability and if the energy bid is unable to be updated. These signals are defined in the wind and solar energy conversion models, found on AEMO's Solar and Wind Energy Forecasting web page.

In the predispatch and ST PASA Short Term Projected Assessment of System Adequacy. A daily load forecast that shows expected demand two to seven days ahead of time. forecast timeframes, participants must manage farm-wide local limitations and element availability information by entering an Upper MW Limit and Turbines/Inverters Available information in the EMMS Energy Market Management System (formerly MMS); software, hardware, network and related processes. portal.

If the Max Avail bid is less than the UIGF for these timeframes, then the availability used by the PD and PASA process is the lower of the two.