Improving Energy Performance in Networks with Semiconductor Converters

The article contains a review of methods of energy performance improvement in power grids with semiconductor converters. Through connecting semiconductor converters to power mains using a special three-phase line reactor, we could reduce the cross-impact of semiconductor converters powered by a common transformer. The use of multi-pulse circuits could help to reduce the harmonic distortion of voltage at the point of a semiconductor converter connection to the power grid. Power grids with a significant presence of higher harmonics generated by nonlinear loads require a use of filter-compensation devices that simultaneously compensate the reactive power of the fundamental frequency and filter the higher harmonic components. The authors describe current wave forms in a power network in the absence of current resonance in higher harmonic components and in its presence. The necessity of the application of anti-resonant reactors in capacitor units is shown. Active filters, which help to create line voltage wave forms that are nearly sine, are considered a potentially productive instrumentation for reactive power compensation. The use of active front end rectifiers makes it possible to implement a two way power exchange with mains supply and thereby to improve the energy performance of the variable-frequency electric drive, to ensure the achievement of power line current that is nearly sine and to gradually adjust the power factor. The authors present the results of a study focused on the influence of the active front end rectifiers on the power quality evidenced from the electrical engineering drilling rig facilities, used for prospecting and exploitation drilling for the oil and gas industry.