Study on Synchronous Machine Model for Power System Harmonic Analysis

With the wide use of power electronic devices in the power system, the produced harmonic has got more concerns. Traditionally, negative impedances of synchronous generation units are widely used to describe the characteristics of synchronous machines in harmonic analysis. Recently, some practical cases call our attention to the impact of control strategies on the model of synchronous machines in power system harmonic analysis. In this paper, firstly, a synchronous model integrated with the exciter, governor and power system stabilizer has been built based on PSCAD, including salient pole machine and not-salient pole machine. Then, the harmonic impedance are studied with Fourier algorithm on the basis of superposition principle. Two methods are used to calculate the impedance of different harmonic: current injection method and voltage source method. Finally, some analysis are conducted according to the simulation results in different cases such as normal operation conditions, power system dynamic, unbalance, etc.