Analysis of balanced and unbalanced faults in power systems using dynamic phasors

This paper extends dynamic phasor models for major elements from single-phase to 3-phase. This kind of 3-phase model can be used to simulate balanced and unbalanced faults conveniently. These models include generator, transmission line (lumped parameter), inductor, and capacitor etc. Among these models, models of transmission line (lumped parameter), inductor and capacitor keep fundamental components of time-varying Fourier coefficients, which are based on generalized averaging method. As for generator's model, we use the Park model, the negative-sequence equivalent circuit and zero-sequence equivalent circuit to compute the positive-sequence, negative-sequence and zero-sequence components, respectively. Furthermore, we considered phasor dynamics of negative-sequence and zero-sequence. These models are "quasi-accurate" models compared with "EMTP-like" models, and are more accurate than "quasistationary" models. All of our models are tested using 3-node network. By comparing our results with the ones from EMTP and PSASP, it is proved, this kind of 3-phase dynamic phasor models has higher precision than "quasi-stationary" models, and it is a middle-kind model between standard time-domain models and "quasistationary" models.