Reserve Regions LOLP Target

Units:	%
Mode:	Input Only
Multi-band:	False
Default Value:	0
Validation Rule:	Between 0 And 100
Key Property:	No
Description:	Loss of Load Probability target for this region

Reserve Regions LOLP Target sets a upper bound on the Loss of Load Probability (for each dispatch period) in the Region specified in the membership in ST Schedule. The unit commitment will attempt to meet the required LOLP Target by making decision of the amount of spinning reserve. The constraint is only statistically satisfied, i.e., the LOLP in the solution can be a little higher or lower than the set target in the region.

The formula for the LOLP constraint, which is integrated into the unit commitment optimization, can be written as:

∑ _{( i )} ( C_i × U_i ) ≤ SR_t ∀t

where t : index of the dispatch period, i : index of the generating unit, SR: total spinning reserve, U : generating unit commitment, C : coefficient of the LOLP constraint.

The coefficient C is calculated for all generators (with FORs) in each period based on the capacity and forced outage rate of all generation units as well as the user provided LOLP target. Since the constraint actually uses the provided LOLP criterion to determine the optimum spinning reserve during the unit commitment, both the spinning reserve and the unit commitment are required in the optimization model which is, therefore, an MIP problem.

It should be noted that the constraint might not be accurate in some cases, such as very small systems (e.g., the number of generating units in service < 20; notice that generators with zero Forced Outage Rate are not included in the calculation of the LOLP constraint coefficients) and systems having a few large units or having large share of units with high forced outage rates. Also, the constraint is only suitable for small LOLP values, e.g., less than 10%; for larger LOLP values, the accuracy is not guaranteed.