Transient Performance Analysis of Shaft Generator Systems

Abstract

A shaft generator system, which consists of a shaft generator, a rectifier, an externally commutated thyristor inverter, an ac reactor, and a synchronous compensator, is widely used in a ship to feed sufficient power to the electric apparatus by using a part of the power produced by the main engine. We have already analyzed the steady-state performances of this type of generating system in some detail. However, transient characteristics of the shaft generator system have been investigated little.
In this paper, transient performances of the shaft generator system are analyzed in detail. A set of transient equations is derived first for the systems with ordinary ac reactor or duplex reactor to achieve output voltage without distortion, and a block diagram representation of the equations is then obtained. Transient responses of the system when the load was changed are calculated through the diagram and compared with experimental results. Also, the block diagram is modified to take the effects of the magnetic-saturation phenomenon of synchronous compensator into account to obtain an accurate simulated result. Moreover, the effects of the duplex reactor and inertia constant of synchronous compensator on the transient responses are clarified for the cases when various system variables are changed.