Simplified Modeling of Power Electronic Interfaced Load Considering Harmonics

The number of electronic devices connected to the power grid through power electronic interfaces, such as inverters or switch power supplies, has increased in recent years. The harmonics generated by power electronic interfaces cannot be avoided. However, existing load models are mainly used for transient electromechanical simulation and only describe the fundamental positive-sequence characteristics of loads without considering harmonics. For in-depth research on distribution networks or microgrids, the harmonic characteristics of loads need to be considered. This paper suggests a simplified power electronic interfaced load model that considers harmonics. The model consists of two parts, one of which characterizes the dynamics of the fundamental current considering the change in fundamental voltage, whereupon the load parameters are determined by analyzing the load's dynamic response to voltage variations. The other part generates output currents containing harmonics based on the effective value and initial phase relationships between the harmonics and fundamental wave obtained from the analysis of steady-state data. An experiment on an inverter air conditioner validates the applicability of the proposed model.