Assessment of the Stability of Synchronous Motors During Three-Phase Voltage Dips Based on Mathematical and Simulation Models of Power Supply Systems

This article presents the results of research on the characteristics of voltage dips occurring in external power supply systems of 110–220 kV due to three-phase short circuits. The studies conducted showed that the residual voltage during short circuits contains a decaying aperiodic component. This work details the investigation into the magnitude and duration of the aperiodic component of the transient process during short circuits in external power supply systems. The obtained results formed the basis for mathematical and simulation models of power supply systems at load nodes with synchronous motors during voltage dips caused by three-phase short circuits in the external network. The simulation model of the synchronous motor STD-8000 with a thyristor excitation system includes the main functional elements of the TE-320 excitation systems, including the connection of the starting resistor in parallel with the excitation winding during disturbances from the power supply, which corresponds to the operational features of the TE-320 excitation system. Studies conducted on the constructed models of the power supply system and synchronous motor demonstrated the influence of the aperiodic voltage component on the current in the excitation winding and the electromagnetic torque of the motor during voltage dips. It was found that the presence of the aperiodic component reduces the allowable duration of power interruption during which the synchronization of the synchronous motor with the network is not disrupted.