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Line Outage Distribution Factors (LODFs)

LODFs for LineX outage

LineX -100%

LineY + 10%

LineZ - 30%

This means that after the outage of LineX, the flow on LineX will decrease by 100 MW (of course), LineY will increase by 10 MW, and LineZ will decrease by 30 MW. The "flow on Line X" here means the flow at the from bus going toward the to bus.

Similarly, sensitivities can be calculated for the insertion of a presently open line. In this case, the LODF determines the percentage of the post-insertion line flow that will come from the other transmission line after the insertion. The "LODF" is better named a Line Closure Distribution Factor (LCDF) in this case.

To calculate the LODFs:

- Perform an initial Power Flow Solution.
- In Run Mode, select Sensitivities > Line Outage Distribution Factors (LODFs) from the
**Run Mode**ribbon group on the Tools ribbon tab to open the Line Outage Distribution Factors Dialog. - Supply the requested information on the Line Outage Distribution Factors Dialog and click the Calculate LODFs button.

What else are LODFs used for?

LODFs are used extensively when modeling the linear impact of contingencies in Simulator. This is true for the calculation of

When calculating "PTDF" values for interfaces that include contingent elements, the PTDF values reported are actually what are referred to as an Outage Transfer Distribution Factor (OTDF). An OTDF is similar to PTDF, except an OTDF provides a linearized approximation of the post-outage change in flow on a transmission line in response to a transaction between the Seller and the Buyer. The OTDF value is a function of PTDF values and LODF values. For a single line outage, the OTDF value for line x during the outage of line y is

OTDFx = PTDFx + LODFx,y * PTDFy

where PTDFx and PTDFy are the PTDFs for line x and y respectively, and LODFx,y is the LODF for line x during the outage of line y. More complex equations are involved when studying contingencies that include multiple line outages, but the basic idea is the same.

When performing Linear ATC analysis along with calculating OTDFs, Simulator determines the linearized approximation of the post-outage flow on the line. This is similarly determined as

OutageFlowX = PreOutageFlowX + LODFx,y* PreOutageFlowY

where PreOutageFlowX and PreOutageFlowY are the pre-outage flow on lines x and y.