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// A Texbook on POWER SYSTEM ENGINEERING
// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar
// DHANPAT RAI & Co.
// SECOND EDITION
// PART II : TRANSMISSION AND DISTRIBUTION
// CHAPTER 11: LOAD FREQUENCY CONTROL AND LOAD SHARING OF POWER GENERATING SOURCES
// EXAMPLE : 11.2 :
// Page number 330-331
clear ; clc ; close ; // Clear the work space and console
// Given data
kVA = 5000.0 // Rating of alternator(kVA)
N = 1500.0 // Speed(rpm)
V = 6600.0 // Voltage(V)
f = 50.0 // Frequency(Hz)
PF = 0.8 // Lagging power factor
x = 0.15 // Short circuit reactance
// Calculations
E = V/3**0.5 // Phase voltage(V)
I = kVA*1000/(3**0.5*V) // Full load current of alternator(A)
V_drop = E*x // Synchronous reactance drop(V)
X = V_drop/I // Synchronous reactance per phase(ohm)
P = 120*f/N // Number of poles
n = N/60 // Speed(rps)
phi = acosd(PF) // Φ(°)
// Case(a)
theta_a = 2.0 // For a 4 pole m/c. 1 mech degree = 2 elect degree
E_s_a = E*sind(theta_a) // Synchronizing voltage(V)
I_s_a = E_s_a/X // Synchronizing current(A)
P_s_a = E*I_s_a // Synchronizing power per phase(W)
P_s_a_total = 3.0*P_s_a // Total synchronizing power(W)
P_s_a_total_kw = P_s_a_total/1000.0 // Total synchronizing power(kW)
T_s_a = P_s_a_total/(2*%pi*n) // Synchronizing torque(N-m)
// Case(b)
sin_phi = sind(phi)
OB = ((E*PF)**2+(E*sin_phi+V_drop)**2)**0.5 // Voltage(V)
E_b = OB // Voltage(V)
alpha_phi = atand((E*sin_phi+V_drop)/(E*PF)) // α+Φ(°)
alpha = alpha_phi-phi // α(°)
E_s_b = 2.0*E_b*sind(2.0/2) // Synchronizing voltage(V)
I_s_b = E_s_b/X // Synchronizing current(A)
P_s_b = E*I_s_b*cosd((alpha+1.0)) // Synchronizing power per phase(W)
P_s_b_total = 3.0*P_s_b // Total synchronizing power(W)
P_s_b_total_kw = P_s_b_total/1000.0 // Total synchronizing power(kW)
T_s_b = P_s_b_total/(2*%pi*n) // Synchronizing torque(N-m)
// Results
disp("PART II - EXAMPLE : 11.2 : SOLUTION :-")
printf("\nCase(a): Synchronizing power for no-load, P_s = %.1f kW", P_s_a_total_kw)
printf("\n Synchronizing torque for no-load, T_s = %.f N-m", T_s_a)
printf("\nCase(b): Synchronizing power at full-load, P_s = %.1f kW", P_s_b_total_kw)
printf("\n Synchronizing torque at full-load, T_s = %.f N-m \n", T_s_b)
printf("\nNOTE: ERROR: Calculation mistakes in textbook")
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