Field tests of a filter to reduce harmonic currents in a three phase fluorescent lamp system

Abstract

This paper presents laboratory and field tests of the filters constructed to reduce harmonic currents generated by three phase systems of fluorescent lamps. The main idea is to develop a filter with high impedance for harmonic currents to reduce harmonic distortion and a with low impedance for flow of the fundamental in asymmetrical regimes. This filter is included in the neutral conductor with the primary role of reducing the zero sequence harmonics. The filter design procedure is based on "levels of aspirations" to reduce harmonic currents. With the use of a lamp equivalent circuit, it provides the required filter impedances for a given harmonic frequency. Rosenbrock's optimization procedure is employed to search for the optimal filter parameters, minimizing the objective function formulated. Laboratory and field tests show that a tuned filter in the neutral conductor can an effective method to reduce harmonic current distortion. It can be applied to any set of discharge lamps arranged as a three phase circuit. The method is especially suitable for high rise buildings and industrial installations where a large amount of electrical energy is consumed by lighting.