Permanent magnet machine (PMG) is usually used as a pair of exciter and to AVR (Automatic voltage regulator) provide a steady voltage.Due to permanent magnet machine is installed on the main generator spindle of a single generator, the power supply voltage not absence made by the main generator terminal voltage，thus Generator AVR Can get a steady supply of power.

To improve the transient performance

When the generator terminal voltage falls due to bear heavy load.If you use well excitation system, the input voltage of AVR will decreases, so that the AVR input enough energy to improve the field current.Permanent magnet machine can provide steady graft for AVR voltage, which can make the field current quickly recover. Reduce the voltage drop, keep the change of the terminal voltage within acceptable range.

Provide greater than three times the last short circuit current

When the generator in dry state of short circuit, the generator excitation system needs to provide enough current well keep enough time, to ensure that the system can can life protection device.And permanent magnet machine excitation system can provide the needed for short circuit current.

Improving the capacity of nonlinear load

Nonlinear load may make harmonic voltage of the generator.If the AVR is provided by the voltage of energy. These harmonics will lead to the failure AVR trigger.And permanent magnet machine as a stand-alone generators, it and there is no electrical connection between synchronous generator, which is a good way to improve the running conditions of AVR.

Ensure enough to magnetic voltage

Installed inside a permanent magnet machine rotor of permanent magnets, able to maintain strong magnetic field for long.When generators need black start. Even if no enough remanent magnetization in core or no spare batteries, permanent magnet machine excitation system can also can build pressure.