Survey of power quality disturbances caused by heat pumps connected to low voltage networks

The increasing proliferation of heat pumps in the residential sector has raised concerns of distribution system operators about their potential impact on power quality in low voltage networks. This paper presents a survey of power quality disturbances caused by heat pumps, focusing on current distortion and voltage changes during the switch-on process. The analysis is based on field measurements of 14 heat pump models under realistic operating conditions. These models represent various types and manufacturers, selected based on a survey of the German market. The results reveal that more than half of the models exhibit significant harmonic and supraharmonic current distortion with magnitudes comparable to fundamental current. Over a quarter of the models have substantial inrush currents, causing significant voltage changes at the point of connection during switch-on. The paper emphasises the need for a closer examination of heat pump characteristics along with their dedicated consideration within the standardisation framework.