Disturbances due to voltage distortion in the kHz range-experiences and mitigation measures

Abstract

Disturbances in power systems due to oscillations of several kilohertz (1 .. 15 kHz) superimposed to the fundamental became more and more important in recent years. The paper discusses causes for this development such as the increased use of PWM converters (e.g. for drives or FACTS devices) or reduction in system damping together with ordinary converter load leading to an excitation of natural system frequency know as commutation oscillations. Measurement results as well as examples from several cases of disturbances investigated by the authors will be presented. The effects of these disturbances vary in a wide range such as malfunction of electronic office equipment, blown power supply units, malfunction of electronic controls or unacceptable noise.

A review of high frequency emission in 2-150 kHz range

“…It shows recurrent oscillations at the end of the notches. The same oscillations can be seen in voltage waveform [21]. It is said to be "commutated oscillations".…”

Traceable measurements of harmonic (2 to 150) kHz emissions in smart grids: uncertainty calculation

“…There is equipment, such as electrical appliances, photovoltaic inverters and electric vehicle chargers, that has power electronic converters with active and passive switching considered non-intentional sources of supraharmonic emissions, whereas transmitters of power line communication (PLC) are considered intentional sources of supraharmonic emissions. The effects of supraharmonic emissions, like interferences in the electrical network generating irregularities in the equipment operation (Unger et al, 2005;Zavoda et al, 2015) or interferences with PLC transmissions operating in the frequency range of 9 to 500 kHz (Rönnberg et al, 2011), can have a significant economic impact. It is therefore important to quantify supraharmonic emissions in order to detect and limit their harmful effects.…”

Unintended consequences of limiting high-frequency emission by small end-user equipment

“…When the motor speed changes, by changing the motor fundamental frequency, the PWM modulation frequency also changes. "Frequencies generated by self-commutated converters with an operating pulse frequency of several kHz" have been reported [3] as a source of disturbances in power systems.…”

“…Distribution transformer failure due to high energy spikes and switching transients [2] and disturbances from PWM converters has been reported [3] giving "malfunction of electronic office equipment, blown power supply units, malfunction of electronic controls or unacceptable noise." This paper will give a brief overview of standards that are currently available to limit emission by power-electronic equipment.…”