The frequency variation of diesel generating set will have negative influences on the users, power plants and electric equipment, for this reason, it is necessary to maintain the frequency at a fixed frequency, 50 Hz or 60 Hz and the variation should not exceed a certain range. When the frequency of the electric system varies, the influences on the users are listed in the following:
1. The rotating speed of the motor used by the users is closely related to the system frequency whose variation will cause the change of the speed of the rotation of the motor, thus influencing the product quality.
2. The instability of the system frequency will influence the normal work of the electronic equipment.
3. As for the main mechanical equipment used in the power station such as draught fan and crushing machine, when the frequency decreases, the blast capacity and water yield supplied by such equipment will drop dramatically, which will influence the normal operation of the boiler.
4. Rotating with low frequency will increase the pressure on the turbine blade, cause the resonance of the blade, shorten its service life and may even break it.
5. When rotating with low frequency, the ventilation quantity of the dynamo will decrease. To maintain normal voltage, it is necessary to increase field current to increase the temperature rise of the stator and the rotor of the dynamo. To make sure that the temperature rise will not exceed the limit, the electric energy production of the diesel generator set will have to be reduced.
6. When running with low frequency, as the magnetic flux density increases, the iron core wear and tear and field current of the transformer will increase. To make sure that the temperature rise will not exceed the limit, the load on the transformer will have to be reduced.
7. When the frequency decreases, the reactive power load in the system will increase, thus reducing the system voltage.
To sum up, every machine is set according to the rated system power and the decrease of system frequency will influence many industries, and if the frequency is too low, the whole system might break down. For this reason, it is very necessary to adjust the frequency of the diesel generating set.
