Module 3 : Frequency Control in a Power System
Lecture 12 : Load Characteristics
Objectives
In this lecture you will learn the following
Load - Frequency characteristic of typical loads.
An example of the characteristics of an induction motor driven fan type load.
Load Frequency Characteristicsa
Normally, loads are a function of frequency. For example, a fan driven by an induction machine
slows down and consumes lesser power if frequency is reduced. In the previous lecture we saw
that a system will settle to a frequency at which load(+losses) and generation is balanced.
Therefore it is instructive to examine the load behavior as a function of frequency.
For simplicity, let's assume voltage and frequency changes are small. In such a case, load can
be represented (in steady state) as follows:
Load Frequency Characteristics (Con td..)
Typical values for various loads are given below:
Component Power factor k_{pv} k_{qv} k_{pf} k_{qf}
Refrigerator 0.80 0.77 2.5 0.53 -1.5
Incandescent lights 1.00 1.55 0.0 0.00 0.0
Fluorescent lights 0.90 0.96 7.4 1.00 -2.8
Lecture 12 : Load Characteristics
Objectives
In this lecture you will learn the following
Load - Frequency characteristic of typical loads.
An example of the characteristics of an induction motor driven fan type load.
Load Frequency Characteristicsa
Normally, loads are a function of frequency. For example, a fan driven by an induction machine
slows down and consumes lesser power if frequency is reduced. In the previous lecture we saw
that a system will settle to a frequency at which load(+losses) and generation is balanced.
Therefore it is instructive to examine the load behavior as a function of frequency.
For simplicity, let's assume voltage and frequency changes are small. In such a case, load can
be represented (in steady state) as follows:
Load Frequency Characteristics (Con td..)
Typical values for various loads are given below:
Component Power factor k_{pv} k_{qv} k_{pf} k_{qf}
Refrigerator 0.80 0.77 2.5 0.53 -1.5
Incandescent lights 1.00 1.55 0.0 0.00 0.0
Fluorescent lights 0.90 0.96 7.4 1.00 -2.8
