Simulating the transients in a load node with a triple-wound transformer at different voltage levels

Abstract

The transient processes in the load node of a power system, which contains powerful induction motors and triple-wound transformers, are simulated. A technique for transient calculation using direct-current synthetic schemes of electric circuits (Dommel’s algorithm) is presented. A dynamic model of an induction motor in the phase domain and a model of a triple-wound transformer based on inductively coupled branches are used taking into account the transformation of voltage levels. It is shown that the mutual influence of different voltage levels in the circuits can be investigated in the phase domain, within one model, and in the course of one simulation process. As an example, we consider a 110/35/10-kV load node that contains an induction motor, a static load, and a reactive power-compensation device in the form of a capacitor on the low-voltage side, as well as power-transmission lines on the medium-voltage side. Dommel’s algorithm makes it possible to investigate various types of nonlinear elements in the system and does not impose any restrictions on the waveform and harmonic composition of signals in the model. The algorithm also allows one to change the parameters and configuration of the timing constraints, which increases the range of the modes considered. When simulating the load node in this domain, various types of asymmetry and complex faults can be considered. The model of the induction motor is highly flexible and yields good results when calculating the dynamic modes.