Instantaneous-Power-Theory-Based Approach for Electromagnetic Transient Modeling of Loads at Bulk Supply Points

This paper develops an approach based on Instantaneous Power Theory (IPT) for electromagnetic transient (EMT) modeling of loads at bulk supply points. The approach is developed because an EMT model can indicate the instantaneous load characteristics with a time step much smaller than the period of the system, which is not applicable to traditional load modeling where only RMS values are concerned. The EMT modeling of loads is to model the instantaneous currents of loads. In the approach, the real and reactive powers of loads are considered as instantaneous powers, and IPT is used to derive the instantaneous currents. The EMT modeling approach is simulated in an equivalent network of a real grid with voltage disturbances and validated with different load models. The load characteristics of all load models in this approach highly match those in traditional load modeling but with a smaller time step than that of traditional load modeling.