E=input( enter the generator voltage: )

V=input( enter the infinite bus voltage: )

Gx=input( enter the reactance of generator: )

L1x=input( enter the line reactance: )

L2x=input( enter the line reactance: )

L3x=input( enter the line reactance: )

L4x=input( enter the line reactance: )

Pi=input( enter the input power: )

X1=Gx+L1x+((L2x*L3x)/(L2x+L3x))+L4x

Pm1=E*V/X1

DO=asin(Pi/Pm1)

A=((L2x*L3x)/(2*(L2x+L3x)))

C=A

B=((L3x/2)^2)/(L2x+L3x)

X2=(Gx+L1x+A)+(L4x+A)+(Gx+L1x+A)*(A+L4x)/B

Pm2=(E*V)/X2

X3=Gx+L1x+L2x+L4x

Pm3=(E*V)/X3

DC=input( enter the fault clearing angle: )

Dm=(3.14-asin(Pi/Pm3))

a1=quad( sin ,DO,DC)

A1=(Pi*(DC-DO)-Pm2*a1)

a2=quad( sin ,DC,Dm)

A2=Pm3*a2-Pi*(Dm-DC)

if(A2>=A1)

disp( the system is stable )

else

disp( the system is unstable )

end

Dcc=acos((Pi*(Dm-DO)-Pm2*(cos(DO))+Pm3*(cos(Dm)))/(Pm3-Pm2))

disp( critical clearing angle: )

D-E=input( enter the generator voltage: )

V=input( enter the infinite bus voltage: )

Gx=input( enter the reactance of generator: )

L1x=input( enter the line reactance: )

L2x=input( enter the line reactance: )

L3x=input( enter the line reactance: )

L4x=input( enter the line reactance: )

Pi=input( enter the input power: )

X1=Gx+L1x+((L2x*L3x)/(L2x+L3x))+L4x

Pm1=E*V/X1

DO=asin(Pi/Pm1)

A=((L2x*L3x)/(2*(L2x+L3x)))

C=A

B=((L3x/2)^2)/(L2x+L3x)

X2=(Gx+L1x+A)+(L4x+A)+(Gx+L1x+A)*(A+L4x)/B

Pm2=(E*V)/X2

X3=Gx+L1x+L2x+L4x

Pm3=(E*V)/X3

DC=input( enter the fault clearing angle: )

Dm=(3.14-asin(Pi/Pm3))

a1=quad( sin ,DO,DC)

A1=(Pi*(DC-DO)-Pm2*a1)

a2=quad( sin ,DC,Dm)

A2=Pm3*a2-Pi*(Dm-DC)

if(A2>=A1)

　　　 disp( the system is stable )

else

　　disp( the system is unstable )

end

Dcc=acos((Pi*(Dm-DO)-Pm2*(cos(DO))+Pm3*(cos(Dm)))/(Pm3-Pm2))

disp( critical clearing angle: )

Dcc