Harmonic resonances in residential low-voltage networks caused by consumer electronics

Abstract

Harmonic resonances in electricity networks can cause significant amplification of harmonic voltages/currents. They can also affect the stable operation of power electronics with internal software controls, like photovoltaic inverters (harmonic instabilities). Up to now capacitor banks are treated as main reason for resonances in residential low-voltage (LV) networks and as long as they are detuned, no resonances at frequencies <2 kHz are expected. However, harmonic measurements in an urban residential network without dedicated capacitor banks have indicated the existence of a significant resonance in the range of 500 Hz. This study presents the results of a detailed study of the network harmonic impedance in this LV network based on measurements and simulations. It shows that residential customers can introduce a significant amount of distributed capacitance, which cannot be neglected. Network harmonic impedance measurements in other residential networks confirm the general existence of such resonances. This study proposes an updated model of residential users for harmonic studies.