Synchronous Generators




Generators are the active elements in the network.They are connected by a shaft to turbines in any type of power plants - to have the same speed and the same torque.

Its speed must be constant and not to vary with load variation. It can be determined by the law:
             W=(120 f / P)                       
where:
                                                                              
W  (r.p.m) : revolution per minute.
P (poles)   : number of generator poles.
f       (Hz)    : frequency .

Modeling of Synchronous Generator  :


The model of synchronous generator is shown in the following figure:




where:

Vt        : Terminal voltage.
Eeff      : Effective emf.
d         : Power angle (rotor angle)
Ra        : Armature resistance.
Xs        : Synchronous reactance
Xa        : Armature reactance
XL        : Leakage reactance.
Ia          : Armature current
Cos j   : Power factor.

Noting that:
                        1 - Xs >> Ra    ,     (Xs / Ra > 10)
                        2 - Xs   = Xa + XL
                        3 - Emf. is always constant (neglecting any change in If).
                        4 - In some times, (Ra) is neglected w.r.t (Xs).

Mathematical model:


The mathematical model of synchronous generator is indicated in the following equation :


- Where  f is the angle between the voltage and the current (the power factor angle).      
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Ahmad Mohammad

Hi. I’m Designer of Mawsoo3a Blog. I’m Electrical Engineer And Blogger Specializing In Electrical Engineering Topics. I’m Creative.I’m Working Now As Maintenance Head Section In An Industrial Company.

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