Estimation of the total current harmonic distortion using an ELF magnetometer

Abstract

The conventional operation of the grid and electrical devices can be disturbed by harmonics, so standards impose strict limits on harmonic current. The entire grid is essential for today’s society, but electromagnetic fields are radiated at their fundamental frequency and harmonics. This paper investigates a methodology to estimate the total current harmonic distortion of the grid by analyzing the magnetic flux density obtained from an extremely low-frequency magnetometer in the 0–2.2 kHz range. A Fast Fourier transform algorithm was applied to determine the magnetic flux density in the frequency domain. By evaluating the ratio of the fundamental component of the magnetic flux density to the harmonics, its total harmonic distortion rate could be deduced. Finally, the data were compared with measurements obtained by two power quality analyzers.