Line Rental

Units:	$
Mode:	Output Only
Multi-band:	False
Default Value:
Validation Rule:
Key Property:	No
Description:	Rental / settlement surplus
Detail:

Line Rental is the economic rent on the line due to congestion.

PLEXOS computes transmission rents in one of two ways as set by the Transmission Rental Method attribute:

1. Point-to-Point
2. Flowgate

Point-to-Point Rent Calculations

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:

• The absolute value of the flow is non-zero; and
• There is a differential in prices.

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.

Rent without Losses

If losses are ignored, transmission rent is calculated using the formula:

Rent = (LineFlow (Price_i - Price_j)

where:

LineFlow is the flow on the line

Price_i is the nodal price (LMP) at the notional receiving end (Node To)

Price_j 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.

Rent with Losses

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) Price_i – (LineFlow⁺ + (1 - LossAllocFactor) × Loss) Price_j

For flows in the counter-reference direction (denoted by - ), the respective rent is:

Rent^- = (LineFlow ^- + (1 - LossAllocFactor) × Loss) Price_i – (LineFlow ^- - Loss Alloc Factor × Loss) Price_j

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%)

Price_i is the nodal price (LMP) at the notional receiving end (Node To)

Price_j is the nodal price (LMP) at the notional sending end (Node From)

Flowgate Rent Calculations

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.

Rent Reporting

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.