EMK:Reserves

Example Reserve Window

EMarket is capable of modelling the Reserves market and co-optimising it with the wholesale electricity market.

To use Reserve Modelling, this option needs to be set in the Dispatch Mode field in the Run Window.

Note: Reserve modelling is significantly more complex than standard nodal modelling, requiring additional run time. It is recommended Reserves modelling is disabled at run time unless you specifically need to produce Reserves data or wish to investigate the interaction of the Reserves and Energy Markets in some detail.

The Reserve Window is used to specify:

1. Reserves-related detail to assist EMarket precisely dispatch Reserves
2. Interruptible Load Reserves details by user-defined Region

The 'Reserve Window has the following components:

1. Details Box (Name and Description)
2. The Regional Reserves box
3. The Interruptible load Reserves box

Regional Reserves Box

Region	The Reserve Offer Region. Note: For the correct operation of the Reserves model at run time all Reserve Regions specified in the Reserves Resource must have corresponding Reserve Regions in the Grid associated with the Run Definition.
RefNode	Reference Node for the Reserve Region.
Base Risk (MW)	The amount of base risk for the region (modeled Reserve risk never falls lower than this value at any time).
Import Risk Subtractor (MW)	This relates to the risk set by lines that are used to import energy into a Region. E.g. a line with a 500 MW capacity imports energy and, for a particular Run Tick, the line flow is 200 MW - if the Import Risk Subtractor setting is 150 (MW), then the risk set by the line is 50 MW (200 MW - 150 MW).
RAF FR	The Fast Reserve adjustment factor.
RAF SR	The Slow Reserve adjustment factor.

Interruptible Load Reserves Box

This is used to enter Fast and Slow ILR Offers by region. ILR Offers can be entered as fixed values or made time dependent using the Array Table and Timeseries Functions.

ILR Box Fields

Type	The type of Reserve the ILR Offer applies to - Fast or Slow.
Region	The Reserve Region the ILR Offer applies to.
Offer Name The name (including band number) of the Offer as it will appear in the Dispatch_FR or Dispatch_SR results.
Quantity (MW)	The Quantity of Reserve offered. This field can be made time-dependent using a formula
Price ($/MWh)	The Price of the Quantity offered in $/MWh

Warning: The ILR Regions must match the Regions specified in the (Reserve) Regions field within the Grid Nodes Box of the Grid Window.

Reserve Modelling and Outputs

To model Reserves using EMarket:

1. Define Reserves Regions in the Reserves Instance to correspond with the Reserve Regions in the Grid Instance you intend to use at run time. These are listed in the Grid Nodes Box of the Grid Window.
2. Set the Unit Size (MW) for Generator Instances that contribute to the risk in a Reserve Region. This is set in the Generic Generator Window appropriately.
3. Set the PLSRSlope setting in the Generator Window appropriately.

PLSRSlope determines how much Reserve can be provided by a plant given its current generation, as given by the formula:

ReserveMAX = PLSRSlope × Generation.

If PLSRSlope is zero, then the Quantity of Reserve that can be provided becomes independent of generation except that the total Reserve provision + the total Generation must be less than or equal to the total Generation offered.

The Output variables produced by Reserve Modelling are explained in the Results Section

How EMarket Determines Generator Risk

During the execution of a Run EMarket uses the following Generator details to determine that Generator's risk for each Tick of the Run:

• Unit Size (MW)
• Total energy (not Reserve) offered
• Max Output (MW)

For example, consider a facility with a Max Output (MW) setting of 500, Energy Offers totaling 610 MW and a Unit Size (MW) setting of 310 MW. EMarket will determine Generator risk with the following process:

• Reduce the total offered from 610MW to 500 MW to match the Max Output.
• Determine two units are required to produce the 500 MW : total Offer divided by unit capacity and rounded up to the next integer. (If the Unit Size (MW) setting was instead 100 MW, for example, five units would be required to produce the 500 MW).
• At this point the Offers are submitted and a dispatch performed on the basis of the Offers
• If the quantity dispatched is 210 MW for the Tick, then the risk set by the Generator is deemed to be 105 MW (210 MW divided by two units). If the dispatch for the next Tick was 450 MW, the risk would be 225 MW. If EMarket had originally determined that five units were required, the risk would be 102 MW or 90 MW respectively.

Note: A Generator with Unit Size (MW) set to zero will not be involved in setting risk, regardless of other settings.

Warning: If no Reserves Instance is specified for a Run, EMarket will not model Reserves. The Reserve Instance for a Run is specified in the Reserve Config field of the Run Window.

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