ABSTRACT

This chapter describes the techniques used in industry to control the flow of harmonic currents produced by nonlinear loads in power systems: network reconfiguration, Increase of short-circuit current ratio, static multipulse power converters with phase shift transformers, series reactors, phase load balancing, and load grouping. The first technique to control harmonic-related problems in industry involved substantial use of single-tuned filters to offer a low-impedance path to harmonic currents. Large harmonic producers, typically in the industrial sector, may be the only producers that adopt harmonic filtering methods to reduce the otherwise multiple disturbances that may arise beyond the metering point and start affecting sensitive equipment and processes. In a stiffer system the voltage drops and therefore harmonic distortion will always be smaller due to its smaller impedance. One measure often advantageous to reduce the effect of unfiltered harmonics is the reconfiguration of the network. Series reactors are to some extent also used as harmonic attenuators in industrial applications.