LOAD FREQUENCY CONTROL- SIMULINK MATLAB

 

AIM:

 

To become familiar with modeling 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 performed 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 the entire 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 area to the scheduled value by adjusting the outputs of the regulating units. This function is referred to as load – frequency control (LFC).

          The single area system consists of the speed governing system, turbine system; regulated system and load are connected.' It is not connected to a network of very large size (infinite bus). When there is change in load the frequency also changes. To balance the change in frequency the regulated system is connected.

          An interconnected power system is divided into a number of control areas for a purpose of load frequency control and they are connected by means of tie lines. When there is change in load in anyone area the frequency also changed. We have to find that change in frequency.

For optimal operation of an interconnected power system the following points are considered

1.     Under normal operating condition, each control area should have the capacity to meet its own load from its own spinning generator, plus the scheduled interchange between the neighboring areas.

2.     Under emergency condition, the energy can be drawn from the spinning reserves of all the neighboring areas immediately due to the sudden loss of generating unit.

          In the two area load frequency control, two individual control areas are connected by the tie line. The control objective now is to regulate the frequency of each area and to simultaneously regulate the tie line power as per inter area power contracts.

  

 

PROGRAM

% Single area system Load frequency control

pr=input(' Enter the total rated capacity ');

pd=input('Enter the nominal operating load');

h=input('Enter the inertia constant');

f=input('Enter the nominal frequency');

r=input('Enter the regulation');

m=input(‘Enter the change in load');

% pr is the base value

d=pd/f;

R=(r*f)j (1OO*pr);

disp(R)

beta=(d+( 1jR));

delfsta =(-m / beta);

disp( delfsta);

 

 

 

% Two area system Load frequency control

pr=input(' Enter the total rated capacity ');

pd=input('Enter the nominal operating load');

h=input('Enter the inertia constant = ');

f=input('Enter the nominal frequency =');

r=input('Enter the regulation = ');

ml=input('Enter the change in load in machine=’);

m2=input('Enter the change in load in machine=’);

pr 1=pr;

pr2=pr;

alpha 12=pr 1/pr2;

d=pd/f;

dl=d;

d2=d;

R=(r*f) / (1 OO*pr);

Rl=R;

R2=R;

beta=(d+( 1/R));

beta 1=beta;

beta2=beta;

delfsta=-((m2+(alpha12*m 1))/ (beta2+(alpha 12*betal)));

disp( delfsta) ;

 

 OUTPUT

                   TWO AREA SYSTEM

Enter the total rated capacity 1500

Enter the nominal operating load 750

Enter the inertia constant= 5

Enter the nominal frequency=50 -

Enter the regulation=3

Enter the change in load in machine one= 0

Enter the change in load in machine two=30

d =15

-0.0148

                   SINGLE AREA SYSTEM

Enter the total rated capacity 1500

Enter the nominal operating load 750

Enter the inertia constant= 5

Enter the nominal frequency=50

Enter the regulation=3

Enter the change in load 30

1.0000e-003

-0.0296

  

RESULT

          Thus the single and two area load frequency control were obtained by using the MATLAB.