Lab 1 - Application Example

One application of thyristor rectifiers is in static excitation systems for synchronous generators. Static excitation systems are used as a means of supplying DC power to the field winding of a synchronous generator. The excitation system also performs control and protective functions, essential to the satisfactory operation of the electric power system. An excitation system is composed of:

an exciter, which provides DC power to the generator field winding.
a regulator, which processes input control signals so that they are able to control the exciter.
a terminal voltage transducer and load compensator, which senses generator terminal voltage then rectifies and filters it to DC quantity.
a power system stabilizer, which provides additional input signals to the regulator to damp power system oscillations.
limiters and protective circuits, that ensure that the capability limits of the exciter and generator are not breeched.

In a static excitation system, all components are stationary. They supply DC directly to the field of the main generator through slip rings, and the AC power supply to the rectifiers is from the main generator or a station auxiliary bus. Thyristor rectifiers are employed for the controlled AC-DC energy conversion stage of a static excitation system, as shown in Figure 5. Further information is provided in references [2]-[4].

Figure 5: Elements of an excitement system.