What is the significance of load modeling in power system? Write down in details the various types of static load modeling represented in power system. Discuss about it with the help of assumptions and approximations involved in it.
Answers
Load models
It is common for aggregate load models to be composed of a static voltage dependent com-
ponent together with an induction motor [4, 7]. This composition can be described paramet-
rically by
Stot = νSv + (1 − ν)Sind (3)
where Stot is the total complex power of the load,
Sv = P0V
ηp + jQ0V
ηq
(4)
describes the voltage dependent part of the load, and Sind is the complex power demanded
by the induction motor component. The dynamics underlying Sind are typically described by
a third order differential equation model [20].
Each of the load components in (3) should be sized to match the total bus demand. The
parameter ν provides the necessary scaling, with 100ν specifying the percentage of static
load. The significance of the load composition, i.e., the weighting between Sv and Sind, can
be captured by the sensitivity of dynamic behaviour to variations in ν. Later examples will
consider uncertainty in ηp, ηq and ν.