Simulator 16 User Guide - PowerWorld

An additional multiplier, pfQMult, can be specified in order to modify the total reactive power
load change to allow adjustment away from the present power factor. This multiplier is 1.0 by
default. The change in reactive power load is then:
Maintaining a constant MW/MVAR ratio implies a sign convention that is lost when applying the
arctan function to the ratio. An additional check is done to make sure that the calculated ΔQ is in
the correct direction (maintains the correct leading or lagging power factor).
When loads are specified as constant power, constant current, and constant impedance
components (ZIP components) rather than simply all constant power, the total load becomes a
function of voltage. Maintaining a constant power factor at each load requires that we use
nominal load (load at 1.0 pu voltage) that does not change as a function of voltage. When only
constant power components are specified, the actual load is the same as the nominal load.
Therefore, in all situations the power factor is determined based on the nominal load.
As MW changes, change the MVAR at a power factor of
This option allows the specification of power factor, pfspecified, for defining the total reactive power
change, ΔQ, at a load. The change in reactive power load is then dependent on the change in
total real power load due to the transfer, ΔP, and this specified power factor.
For this option, ΔQ is assumed to be in the same direction (has the same sign) as ΔP .
Load Component Variation
The total real power load change, ΔP, at a load during a PV transfer is determined by the load's
participation factor as defined with its associated injection group and the amount of transfer that is
being implemented. The total reactive power load change, ΔQ, is determined by the option selected
for how reactive power should change during ramping as explained in the previous section. Total
load change, (ΔP,ΔQ), at a load can be broken into ZIP components for constant power (ΔPS,ΔQS),
constant current (ΔPI,ΔQI), and constant impedance (ΔPZ,ΔQZ). During the PV transfer, the user can
specify how changes in load due to the transfer should be split among these components.
The constant current and constant impedance components are a function of voltage and the nominal
values specified for these components. Because of this, it becomes important to determine the load
changes for the components based on nominal voltage and then apply these changes to the nominal
components.
All changes apply to constant power (S MW, S MVAR)
All changes to load will be made to the constant power component:
The constant power component of load is not dependent on voltage so the total load change can
be applied directly to the constant power component.
Vary in proportion to existing Z,I,P ratios
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