A closed-loop auto-frequency regulating system consists of AC excitation synchronous generator with multiphase AC excitation coil, variable frequency excitation unit and frequency regulator. Its characteristic is that variable frequency excitation unit and AC excitation coil are linked with a fixed phase sequence. Based on the regulated quantity of output by the frequency regulator, multiphase AC with a fixed range of frequency is generated for the AC excitation of the generator. The prime motor is allowed to choose operating speed freely, and the operating speed may be close to or reach the best operating state. The system has broader range of frequency regulation and higher precision of frequency control. It can be used as mating generator in hydraulic power station or other kinds of power station. |