Simulator 16 User Guide - PowerWorld

The loss sensitivities are calculated by modeling an injection of power at a bus and then assuming that
this injection is absorbed by the island slack bus. The sensitivity then shows how much the losses (for
the region of interest) increase when you transfer 1 MW at the injection bus to the island slack. The
"region of interest" is what was chosen as Island, Each Area, or Selected Areas.
Therefore, the "absolute numbers" given by the loss sensitivity dialogs are not directly meaningful
because we are always assuming that the absorbing point is the island slack bus. What is meaningful
is the "difference" between sensitivity numbers.
Example:
Assume the sensitivities are calculated to be
Bus A Loss MW Sensitivity = -0.04 = Asens
Bus B Loss MW Sensitivity = -0.02 = Bsens
Bus C Loss MW Sensitivity = +0.03 = Csens
Using these we can then look at the sensitivity of generic transfers between these buses by using
"superposition".
Consider the following change in injections modeling a transfer of power from Bus A to Buses B and C.
Bus A injection = +10 MW = AMW
Bus B injection = - 6 MW = BMW
Bus C injection = - 4 MW = CMW
An estimate of the change in losses can then be calculated as
Loss Change = (AMW)(Asens) + (BMW)(Bsens) + (CMW)(Csens)
= (+10)(-0.04) + (- 6)(-0.02) + (- 4)(+0.03)
= -0.4 MW
The Bus Marginal Loss Sensitivities Dialog houses the following controls:
Selected Areas Table
This table is used only when the Loss Function Type is set to Selected Areas; otherwise, it is
ignored. Left-click on the Include field to include or exclude areas from the loss function.
Calculate Marginal Loss Sensitivities Button
Once the loss function type has been specified, click this button to calculate the bus marginal loss
sensitivities and update the Bus Marginal Loss Sensitivities table.
Bus Marginal Loss Sensitivities Table
This table shows the bus marginal loss sensitivities for all buses with valid Area/Zone/Owner filters.
The Bus Marginal Loss Sensitivities Table is a type of Case Information Display and thus exhibits
features and behavior similar to all other case information displays. It has a local menu from which
you can choose to find out more about a particular bus. You can sort records by any of the listed
fields by clicking on the column headings. The table contains the following fields:
Number, Name: Number and name of the bus.
Area Number, Area Name: Number and name of the bus’ area.
Loss MW Sens:. Sensitivity of the loss function to an increase in the real power injection
(generated power assumed positive) at the bus.
Penalty Factors: Computed penalty factor of each bus.
MVR Sens:. Sensitivity of the loss function to an increase in the reactive power injection
(generated power assumed positive) at the bus.
©2011 PowerWorld Corporation
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