Measurement-based Harmonic Current Modeling of Agricultural Heat Pumps

The inverter equipment that is intensively connected to a specific distribution system, such as a heat pump for agriculture (HPA), may be the main cause of harmonic voltage distortion. In order to specifically examine the countermeasures about harmonic voltage distortion, it is necessary to perform harmonic analysis after considering the harmonic state according to the operating condition of the equipment. In this study, we measured the characteristics of harmonic currents generated from actual HPA and developed a model that accurately reproduces these characteristics. The results established that a fourth-order polynomial approximation effectively creates a model that reproduces the characteristics of harmonic current. By using this polynomial approximation, the effective value and phase of the harmonic current generated from the HPA can be modeled in any operating state, and detailed harmonic analysis can be performed.