Transmission Internal VoLL

Units:	$
Default Value:	100000
Validation Rule:	Between 0 And 1E+9
Description:	Value of Lost Load used internally

Transmission Internal VoLL is the mathematical 'value of lost load' as used inside the optimization when unserved energy is allowed. This differs from the 'accounting value of lost load', which is used ex-post to calculate the cost of curtailment. For example, some markets set true VoLL to relatively low $250/MWh. At this price some constraints such a fuel limits, emission limits could easily generate shadow prices above VoLL and hence cause unserved energy when generation resources are available. But with internal VoLL is set to a very high number the optimization chooses available generation and transmission resources ahead of load-shedding.

NOTE:

• In reporting, nodal and regional prices are always capped at VoLL (not internal VoLL), however reported constraint shadow prices may exceed VoLL, indicating that internal VoLL was active.
• Interval VoLL can be specified as a multi-band input by Region for a more granular approach.