NEMforecast - Getting the most out of your licence

NEMMCO ST PASA Data

The chart above is a snapshot of the charting incorporated in NEMforecast for NEMMCO's ST PASA data set - charts are shown for the Queensland and NSW region. Similar charts are available for the other regions.

The (red) vertical status bar can be moved left or right (see the instructions for adjusting the timeline slider) to highlight an individual half-hour in which the user has a particular interest. The selected half-hour can then be viewed in more detail in the Geographical View (in conjunction with daily weather forecasts for the relevant day, as supplied by the Bureau of Meteorology).

The user can choose whether to show 1, 2 or 4 charts per screen by use of the controls provided. The user can also choose to show (or hide) any of the data points by ticking (or unticking) the relevant data series.

The following table provides an explanation of the data provided by NEMMCO, and facilitated in NEMforecast (in the same order as they are shown in NEMforecast):

Short-Term Viewer (Regional Charts)
Name	NEMMCO Definition	Comments by global-roam
Surplus Capacity	Region surplus capacity, +/- value indicates surplus/deficit capacity respectively	This is the excess of unconstrained capacity over the 10% POE demand
Constrained Capacity	Available capacity (MW) in this region energy constrained MW capacity subject to energy and network security constraints	Generators will make capacity available to the market, though in some cases NEMMCO may determine that some of this capacity will not be available due to energy constraints or network limitations. For instance, Wivenhoe pumped storage hydro may have 500MW of installed capacity, however a portion of this capacity will be constrained at different points in time due to the station's need to refill its reservoir levels at times of off-peak spot market price.
Max Surplus Reserve	The Maximum Surplus Reserve evaluated for this region in this period. Calculated for each region in turn.	This result is calculated just looking at this region in particular and assumes all reserves in other regions will be available. Hence, it is an optimistic number.
Aggregate Scheduled Load	The Sum of Capacity Available ... for load traders in this region in this period.	Models the amount of demand-side management known by NEMMCO to be consistently available in the region.
Net Interchange Under Scarcity	Net export in MW out of this region in the capacity adequacy evaluation. Export is >0 and import if <0.	If there is insufficient local reserve, the interconnectors may need to flow in order to transfer reserve from a neighbouring region. This variable reveals when this is the case.
Reserve Req	Input reserve Requirement	This amount is set for each year by NEMMCO as a result of probabilistic modelling. Through this process, NEMMCO translates the Reliability Panel's reliability standard (< 0.002% USE) into deterministic values of minimum reserves. For further information about the reserve levels applicable currently, and the methodology for calculating them, please see the NEMMCO website.
Surplus Reserve	Regional reserve surplus. +/- values indicate surplus/deficit reserve respectively.	This value is calculated by NEMMCO through a non-priced-based, NEM-wide dispatch that seeks the optimum sharing of reserves across the NEM. On the charts in NEMforecast, this is shown on the right-hand axis as this is seen as the key variable of interest to NEMforecast users.
Unconstrained Capacity	Region energy unconstrained MW capacity subject to energy and network security constraints	This is the amount of capacity that participants are currently saying will be available to the region in the given half-hour AND which NEMMCO determines will not be constrained from supplying to the market.
Aggregate Capacity Available	The Sum of Capacity Available for generator traders in this region in this period	Constrained + Unconstrained Capacity
Aggregate PASA Availability	Aggregate regional physical plant capability including any capability that can be made available within 24 hours	A number higher than "Aggregate Capacity Available" because it also takes into account plant that is not intended to be available, but which could be made available if requested by NEMMCO.
Capacity Req	Demand + Reserve Requirement	The key point to note here is that NEMMCO assumes the 10%POE demand - hence this requirement represents an extreme weather condition for the half-hour in question.
Demand 90	Input value for 90% probability demand	Low weather conditions. As would be expected, actual demand levels have been consistently higher than the 90% forecasts as these set the lower bounds.
Demand 50	Input value for 50% probability demand	Average weather conditions
Demand 10	Input value for 10% probability demand	The demand anticipated if the half-hour should experience extreme weather conditions (e.g. exceptionally hot in summer or exceptionally cold in winter)
Energy Req Demand 50	Sum of: (Region Period Demand - given Demand50)/Period (sum by trading day, entered into the first period of the trading day - GWh)	This is simply the forecast energy consumed in the region for the given day (under the 50% POE demand trace). Data is entered for 04:30 as this is the first trading period in the day. In the graphical viewer, the measure of the numbers is shown above each bar in light grey.

Similarly, the following image is a snapshot taken of the interconnector variables charted (from the NEMMCO ST PASA dataset) in NEMforecast. An explanation of the terms involved is also included:

Short-Term Viewer (Interconnector Charts)
Name	NEMMCO Definition	Comments by global-roam
Capacity MW Flow	Interconnector loading level (MW) that can be reached in case of capacity scarcity in neighbouring regions subject to network and energy constraints.	The flow on the interconnector deemed by NEMMCO necessary to flow for the 1/2-hour in the case whereby a region would otherwise have a deficit of surplus reserve.
Capacity Violation Degree	Capacity adequacy assessment violation degree, 0 if not violating. Where: CapacityMWFlow = export + violation Degree (Deficit) CapacityMWFlow = import + Capacity Violation Degree (Deficit)	By default this variable is not displayed on the charts (though the user can opt to show).
Capacity Marginal Value	Capacity adequacy assessment marginal value, 0 if not binding	By default this variable is not displayed on the charts (though the user can opt to show).
Calculated Import Limit	Calculated Interconnector limit of importing energy on the basis of invoked constraints and static interconnector import limit. Not unlike the input interconnector import limit this is a directional quantity and should be defined with respect to the interconnector flow.	Similar data as is produced in real-time dispatch for each interconnector.
Calculated Export Limit	Calculated Interconnector limit of exporting energy on the basis of invoked constraints and static interconnector export limit.	Similar data as is produced in real-time dispatch for each interconnector.