Reduced-order electromagnetic transient model based on equivalent flux linkage derivative for induction motors under voltage sag condition

Precise electromagnetic transient simulation of induction motors (IMs) under voltage sag condition is necessary in Electro-Magnetic Transient Programme. Although traditional fifth-order model can accurately reflect the electromagnetic transient behaviour of IMs, the disadvantage of massive computation limits its application in the large-scale system simulation. Considering voltage sag is a typical power quality issue, a novel reduced-order electromagnetic transient model based on equivalent flux linkage derivative is proposed to shorten simulation time during voltage sag. When characteristic parameters of voltage sag are given, an equivalent flux linkage derivative can be obtained simply, and the proposed model can effectively shorten the simulation time while ensuring accuracy of the fifth-order model. Simulation results of small capacity (5.5-kW) and large capacity (315-kW and 1600-kW) IMs in simple system and IEEE 9-bus system confirm the applicability of the proposed model. It is estimated that simulation time of the proposed model decreases by 76% compared with the fifth-order model. Finally, the experimental validation with the 5.5-kW IM is carried out to show the effectiveness of the theory.