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FACTORS INFLUENCING TRANSIENT STABILITY

Many factors affect the transient stability of a generator in a practical power system. From the small system analyzed above, the following factors can be identified:

Ø The post-disturbance system reactance as seen from the generator. The weaker the post-disturbance system, the lower the Pmax will be.

Ø The duration of the fault clearing time. The longer the fault is applied, the longer the rotor will be accelerated and the more kinetic energy will be gained. The more energy that is gained during acceleration, the more difficult it is to dissipate it during deceleration.

Ø The inertia of the generator. The higher the inertia, the slower the rate of change of angle and the lesser the kinetic energy gained during the fault.

Ø The generator internal voltage (determined by excitation system) and infinite bus voltage (system voltage). The lower these voltages, the lower the Pmax will be.

Ø The generator loading before the disturbance. The higher the loading, the closer the unit will be to Pmax, which means that during acceleration, it is more likely to become unstable.

Ø The generator internal reactance. The lower the reactance, the higher the peak power and the lower the initial rotor angle.

Ø The generator output during the fault. This is a function of faults location and type of fault.

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