Frequency Control in the Presence of Dynamic Model of Induction Motor Based on Virtual Inertia

In this article, a fifth-order dynamic model is introduced for electrical loads of the induction motor type, which is further reduced to a model of the third and first orders. In the following, it is shown that with the increase of motor inertia, the error of low-order models increases compared to the main model. Of course, with an acceptable approximation, the first-order model can be chosen as the engine model. By adding the induction motor as a dynamic load to a microgrid, it has been shown that, except some special cases, a fixed coefficient cannot be utilized to simulate and represent the induction motor. The next goal of this article is to design virtual inertia as the primary controller to reduce and control the frequency changes of a microgrid. Considering that wind turbine tracks the highest power output at different wind speeds, it cannot engage in the mode of frequency control of the microgrid, therefore, for the participation of the wind turbine in frequency regulation, virtual inertia has been brought to turbine to lessen the frequency adjustments and with growing the virtual inertia model of an induction motor may be decreased to first-order.