Chapter Three - Synchronous machine modelling

Abstract

This chapter covers the simulation model for synchronous machines. First, the general operation of synchronous machines is described, detailing the differences between cylindrical rotor and salient pole machines. Next, a simple study system is introduced, the single machine infinite bus system. In the second section, the d-q and D-Q reference frames are introduced, which are essential for synchronous machine modelling. Dynamic equations for the machine modelling are provided. The model considers only the operation of the generator within its capability curve. Various limits such as rotor field heating current limit, stator heating current limit, armature core end iron heating limit, stability limit, etc., need to be modelled additionally. The initialization procedure to determine a steady-state operating point of the synchronous machine model is described, where the initialization is described both for system base and machine base. The Simulink implementation is described step by step, including the initial conditions. The Simulink section explicitly explains how to model the generator in machine base and system base. The reader is instructed into the art of debugging Simulink models in a methodical manner, leading to a working model. By the end of the chapter, the reader will be ready to run a time domain simulation with a synchronous machine in machine and system base and understand how the results compare. Various dynamic synchronous machine models are introduced, to raise awareness among the reader about the different modelling assumptions made. The chapter concludes with step-by-step guidance of building a dynamic simulation model for a two-area test system consisting of four synchronous machines.