Analysis of voltage and current harmonics and the risk of resonance in a network with power capacitors

Abstract

The purpose of the analysis of measurement results of harmonics presented in this paper is to predict the potential dangers after installation of capacitor banks in a medium-voltage (6 kV) network of the Kolubara open pit mine. Although the measured values for most of the harmonic voltages are lower than the maximum allowed values for medium-voltage networks, there is a risk of resonant occurrences of certain harmonics. It is shown that the resonant harmonic currents of the 11th to 25th orders can increase up to 10 times. These increases in harmonic currents could not overload network elements, but they could lead to overload and outage of the power capacitors. It is particularly important to note that the (quasi-) resonant phenomenon, which is common for harmonics between the 11th and the 25th order, is difficult to avoid without performing additional measures.

Keywords

• MV network
• higher harmonics
• resonance phenomena
• power factor correction