Module 3 : Frequency Control in a Power System
Lecture 11 : Definition of Frequency
What determines grid frequency?s
While it has been stressed that frequency is the same in steady state throughout a
synchronous grid, two very interesting questions need to be answered:
What is the precise value of frequency to which a system will settle?
How does the "system frequency" vary during transients? How does one obtain a useful
definition of frequency when individual generators speeds can be different during transients?
To understand this we need to look at the basic governing equations of synchronous machines
in a system.
We know that for the ith generator,
Note : Pmi and Pei denote the per unit mechanical and electrical powers respectively.
Lecture 11 : Definition of Frequency
What determines grid frequency?s
While it has been stressed that frequency is the same in steady state throughout a
synchronous grid, two very interesting questions need to be answered:
What is the precise value of frequency to which a system will settle?
How does the "system frequency" vary during transients? How does one obtain a useful
definition of frequency when individual generators speeds can be different during transients?
To understand this we need to look at the basic governing equations of synchronous machines
in a system.
We know that for the ith generator,
Note : Pmi and Pei denote the per unit mechanical and electrical powers respectively.
