Harmonic modelling of synchronous machines

The connection of power converter and other nonlinear loads to the electrical power system results in other system components being subject to voltage waveform distortion. In order to predict the resultant heating and harmonic current flows, it is necessary to have fairly accurate models for components such as synchronous machinery. The paper presents a theoretical and experimental study into the electrical behaviour of synchronous machines when subjected to harmonic voltage disturbance at the terminals. It is shown that the time-varying nature of the machine inductances results in current flow at both the applied and at an associated harmonic frequency. Consequently, it is inadequate to model the machinery by a pure reactance at each harmonic frequency.