| Units: | $ |
| Mode: | Output Only |
| Multi-band: | False |
| Default Value: | |
| Validation Rule: | |
| Key Property: | No |
| Description: | Rental / settlement surplus |
Line Rental Total is the economic rent on the line due to congestion. It's calculated as the base case Rental plus sum of post-contingency flow multiplied by post-contingency shadow price, for all contingencies that the element is binding under.
PLEXOS computes transmission rents in one of two ways as set by the Transmission Rental Method attribute:
The rent is computed as the price differential across the line multiplied by the amount of flow on the line. Therefore rent will accumulate if:
Price differentials occur across nodes in the network in the presence of congestion (regardless of whether or not the line in question is involved in a constraint) and also due to losses. Thus rents can accumulate on a line even if it is not congested or involved in other constraints such as interface limits.
If losses are ignored, transmission rent is calculated using the formula:
Rent = (LineFlow (Pricei - Pricej)
where:
LineFlow is the flow on the line
Pricei is the nodal price (LMP) at the notional receiving end (Node To)
Pricej is the nodal price (LMP) at the notional sending end (Node From)
Note that LineFlow is positive for flows in the reference direction and negative for flows in the counter-reference direction.
When losses are modelled the flow variables are directional, thus for flows in the reference direction (denoted by + ) the respective rent is:
Rent+ = (LineFlow+ – LossAllocFactor × Loss) Pricei – (LineFlow+ + (1 - LossAllocFactor) × Loss) Pricej
For flows in the counter-reference direction (denoted by - ), the respective rent is:
Rent- = (LineFlow - + (1 - LossAllocFactor) × Loss) Pricei – (LineFlow - - Loss Alloc Factor × Loss) Pricej
Rent = Rent+ + Rent-
where:
LineFlow+ is the non-negative flow in the reference direction
LineFlow - is the non-negative flow in the counter-reference direction
LossAllocFactor is the proportion of losses allocated to the notional receiving end (default is 0.5 = 50%)
Pricei is the nodal price (LMP) at the notional receiving end (Node To)
Pricej is the nodal price (LMP) at the notional sending end (Node From)
The rent is computed as the shadow price on any constraint involving the line multiplied by the activity of the line in the constraint. All constraints involving the line must be accounted for, thus this method does not compute rents correctly in the 'general' case i.e. the rent calculation will be correct when only line thermal limits, contingency limits and interface limits are applied, but might not be correct if generic constraints are applied to lines.
Rents on transmission lines that flow inside a region accumulate into the Region Intraregional Transmission Rental total. Rents on lines that are interregional are assigned to the sending and receiving regions according to the Line Loss Allocation. The default (if not specified) is a 50/50 split of the rents between the regions. These totals are then reported as Region Interregional Transmission Rental.
Companies that own transmission lines (Line Companies collection) accumulate the transmission rentals from those lines. These rents appear in the Company Net Revenue and will affect the dynamic bidding of companies.