# MATLAB Application for Load Frequency Dynamics of Single Area Power Systems | EE1404 – Power System Simulation Laboratory

AIM:
To become familiar with modelling and analysis of the frequency and tie-line flow
dynamics of a power system without and with load frequency controllers (LFC) and to design
better controllers for getting better responses.

THEORY:
Active power control is one of the important control actions to be perform to be normal
operation of the system to match the system generation with the continuously changing system
load in order to maintain the constancy of system frequency to a fine tolerance level. This is one of
the foremost requirements in proving quality power supply. A change in system load cases a
change in the speed of all rotating masses ( Turbine – generator rotor systems) of the system
leading to change in system frequency. The speed change form synchronous speed initiates the
governor control (primary control) action result in all the participating generator – turbine units
taking up the change in load, stabilizing system frequency. Restoration of frequency to nominal
value requires secondary control action which adjust the load - reference set points of selected (
regulating) generator – turbine units. The primary objectives of
automatic generation control
(AGC) are to regulate system frequency to the set nominal value and also to regulate the net
interchange of each areas to the scheduled value by adjusting the outputs of the regulating units.
This function is referred to as load – frequency control(LFC).

PROCEDURE:
1. Enter the command window of the MATLAB.
2. Create a new Model by selecting File - New – Model
3. Pick up the blocks from the simulink library browser and form a block diagram.
4. After forming the block diagram , save the block diagram.
5. Double click the scope and view the result.

EXERCISE:
1.An isolated power station has the following parameters
Turbine time constant tT = 0.5sec
Governor time constant tg = 0.2sec
Generator inertia constant H = 5sec
Governor speed regulation = R per unit
The load varies by 0.8 percent for a 1 percent change in frequency , i.e,D = 0.8
(a) Use the Routh – Hurwitz array to find the range of R for control system stability.
(b) Use MATLAB to obtain the root locus plot.
(c) The governor speed regulation is set to R = 0.05 per unit.The turbine rated output is 250MW
at nominal frequency of 60Hz. A sudden load change of 50MW( PL = 0.2 per unit) occurs.
(i) Find the steady state frequency deviation in Hz.
(ii) Use MATLAB to obtain the time domain performance specifications and the frequency
deviation step response.

RESULT:
Finally, became familiar with modelling and analysis of the frequency and tie-line flow
dynamics of a power system without and with load frequency controllers (LFC) and to design
better controllers for getting better responses.
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