Abstract: A harmonic mitigating device for connection between a power distribution system and the load uses a magnetic shunt to control the levels of magnetic coupling between different elements of the device while providing all windings on a single core. This allows for the reduction or elimination of the harmonic MMF induced in the line winding of the device, and as a result the reduction of harmonic currents flowing into the power supply system; and the reduction of the line winding inductance, which in turn reduces the voltage boost of the device under the no-load conditions, reduces the voltage drop at full load conditions and increases the stability of the drive. The invention serves to reduce ripple level in rectifier outputs and buffers transient overvoltages, and a single configuration works with any rectifier type, including SCR bridges.

Abstract: A harmonic mitigating device also functions as a phase converter for supplying single-phase non-linear loads, or as a phase shifting device for three-phase non-linear loads with multiple inputs to create a quasi multi-pulse system. A multiple-winding reactor or a plurality of single-winding reactors, and at least one capacitor, are connected in a crosslink circuit between the reactor windings, or between the reactor windings and another line. At least one reactive element comprising a line winding is connected to each phase or to the neutral and in series with a non-linear load, which provides a high reactance to harmonic currents, and at least one crosslink circuit comprising a second reactive element connected between the second end of the line winding and a capacitor which is connected to any other line in the system.

Abstract: A harmonic mitigating device also functions as a phase converter for supplying single-phase non-linear loads, or as a phase shifting device for three-phase non-linear loads with multiple inputs to create a quasi multi-pulse system. A multiple-winding reactor or a plurality of single-winding reactors, and at least one capacitor, are connected in a crosslink circuit between the reactor windings, or between the reactor windings and another line. At least one reactive element comprising a line winding is connected to each phase or to the neutral and in series with a non-linear load, which provides a high reactance to harmonic currents, and at least one crosslink circuit comprising a second reactive element connected between the second end of the line winding and a capacitor which is connected to any other line in the system.

Abstract: A voltage drop compensating reactor connected between the power distribution system and the load provides a flux shifting multiple-winding reactor with a capacitor bank connected between the reactor windings. At least one line winding is oriented in a first polarity on a core, and at least one compensating winding oriented in the opposite polarity on the core and connected between the output of the first winding and the load. The opposing fluxes generated by the line winding and the compensating winding cancel and the total reactance of the device is lower than the reactance of the line winding. The input of a cross-link circuit comprising a capacitor is connected between the line winding and the compensating winding. The reactance through the cross-link circuit to the neutral (or another phase) is lower than the reactance through the line winding.

Abstract: A harmonic mitigating device connected between the power distribution system and the load provides a flux shifting multiple-winding reactor with a capacitor bank connected between the reactor windings. At least one line winding is oriented in a first polarity on a core, and at least one compensating winding oriented in the opposite polarity on the core and connected between the output of the first winding and the load. The opposing fluxes generated by the line winding and the compensating winding cancel and thus reduce the through-reactance of the device between the load and the power supply. The input of a cross-link circuit comprising a capacitor is connected between the line winding and the compensating winding. The reactance through the cross-link circuit to the neutral (or another phase) is lower than the reactance through the line winding. Harmonic currents thus flow through the cross-link circuit, and are largely prevented from penetrating the power distribution system.

Abstract: A phase shifting transformer or autotransformer for a three phase power distribution network in which selected outputs have a low zero phase sequence impedance. At least one low zero phase sequence impedance output is fed by a plurality of windings distributed amongst the three core legs such that the number of turns of windings generating a flux in the positive direction is substantially equal to the number of turns of windings generating a flux in the negative direction. Thus, according to the invention, the transformer may be provided with any necessary phase shifting angles between different harmonic sources, with some or all outputs having a low zero phase sequence impedance to reduce voltage distortion created by zero phase sequence harmonics.

Abstract: A phase shifting transformer or autotransformer for a three phase power distribution network has a secondary winding including a plurality of windings distributed amongst the three core legs such that on each core leg the number of turns of windings generating a flux in the positive direction is substantially equal to the number of turns of windings generating a flux in the negative direction. Thus, according to the invention, the transformer may be provided with any necessary phase shifting angles between different harmonic sources, with outputs each having a very low zero phase sequence impedance to reduce voltage distortion created by zero phase sequence harmonics.

Abstract: A phase shifting polygonal transformer or autotransformer for a three phase electrical distribution system is provided, in which the transformer output winding or autotransformer winding is composed solely of three main coils and three auxiliary coils, alternately interconnected in series. The outputs for the transformer/autotransformer are connected to taps in the coils offset from the connections between coils, which eliminates the need for multiple auxiliary coils in each phase. The transformer/autotransformer of the invention is thus much simpler and less expensive to manufacture than a conventional phase shifting transformer or autotransformer, but reduces harmonics just as effectively.

Abstract: The invention provides a zero phase sequence current zig-zag filter with adjustable zero phase sequence impedance and a method for adjusting the impedance of the filter. Impedance is adjusted in discrete increments by detuning the filter one phase at a time. Detuning is accomplished using taps or auxiliary windings, whereby the ratio of the effective number of turns of the first winding relative to the second winding on the same core leg is changed independently for each phase of a three phase power supply.