A New Excitation System for Synchronous Alternators

A new method for exciting alternators is presented. Each rotor pole of the alternator consists of two adjacent half-poles on two axes at 90 electrical degrees from each other. The resultant magnetic field can be made to revolve with respect to the rotor. This is achieved by means of a set of movable brushes around the commutator of the exciter. Investigations on the frequency and transient stability of the alternator with the new excitation system are carried out. The results show that by using the new excitation system, it is possible to improve the transient stability of an alternator connected to an infinite busbar and to stabilize the frequency of an alternator when the latter acts as the sole power source.