Distribution Factor (DFAX)
Distribution Factor (DFAX) represents the sensitivity of power flow on a transmission asset (like a line or transformer) to a change in power, injection or withdrawal, at a specific point in the grid.
DFAX measures how much the flow on a transmission line changes for a given change in power at a particular bus.
Why does it matter for developers?
DFAX is helpful in understanding the impact of your project on a given constraint. This impact (DFAX) is also used to calculate the allocated costs you’ll be responsible for out of the total upgrade cost for an element.
For example, a constraint with a DFAX of 0.5 (50%) indicates that under a specific scenario (including contingency events), 50% of the power flows through the monitored facility or limiting element where the constraint was identified. For a 100 MW project, this equates to 50 MW. A project's MW impact determines its share of the cost responsibility relative to all projects affecting the monitored facility.