Practical application of fiber-optic current sensor in power system harmonic measurement

This paper presents a portable fiber-optic current sensor (FOCS), modified for current harmonic measurement in high-voltage electric power systems. The details of the sensing head redesign are illustrated. Also, both electronic processing block and harmonic analysis algorithm have been illustrated. The practical application of the so-redesigned device has been successfully verified experimentally at a thermal power plant. The measurements have been made for the operation of a 6-kV induction motor with different load conditions and the thyristor excitation of a 15-kV alternating current generator. The experimentally determined current waveforms, the corresponding relative harmonic content computed by discrete Fourier transform, and total harmonic current distortion for various measuring points have been displayed. Important requirements for accurate harmonic measurements have been discussed. The results clearly verified the applicability of the FOCS for monitoring electric power quality as suggested in this paper