The system shown below has 100 MVA and 132 kV bases. Reactances are shown below.
We need to calculate the limiting powers for the system for three types of voltage regulation.
Each of the below conditions will give different values of maximum power output, depending on the speed of the AVR, and the effect on the operation chart of the synchronous generator. The output can be increased up to heating limit of the stator winding.
We need to calculate the limiting powers for the system for three types of voltage regulation.
Each of the below conditions will give different values of maximum power output, depending on the speed of the AVR, and the effect on the operation chart of the synchronous generator. The output can be increased up to heating limit of the stator winding.
- Fixed excitation and constant no-load voltage (no regulator action). Without the AVR the terminal voltage of the machine V will fall with increased angle, the generated voltage E being constant and the power reaching a maximum at 90 degrees.
- Operation of AVR, not continuously acting. When a generator has passed through the steady-state limiting angle with a fast-acting AVR, it is possible for synchronism to be retained. The AVR, in forcing up the voltage, increases the power output of the machine.
- Very fast AVR action, keeping terminal voltage constant. With a perfect AVR, V is maintained constant, E being increased with increase in angle. As P=(EV/X) sin delta, it is evident that power will increase beyond 90 degrees until the excitation limit is reached.

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