A multi-star synchronous machine model for real-time digital simulation and its applications

Abstract

Poly-phase electric machines have the advantages of low ripple in torque, better fault tolerance and high reliability in operation. Such properties make them attractive for applications in renewable energies, electric ship propulsion, traction, aircraft systems and electric vehicles [1,2]. Failure of the drive system through a few phases could be tolerated by operating the remaining phases of the machine. One popular group amongst poly-phase electric machines is the category of multi-star machines.This paper presents development and validation of a multi-star synchronous machine model for a real-time digital simulator. The paper starts with the introduction and analysis of multi-star machines. A generalized method of Vector-Space Decomposition (VSD) is introduced for analyzing machines with an arbitrary number of stars. The method of incorporating the model into the network solution of real-time electromagnetic transient program is described. For the purpose of demonstration, a typical circuit of a marine electric vessel, containing poly-phase generators, power electronic converters, DC bus, hotel load, battery, and poly-phase propulsion systems is simulated in real time.