Voltage Fluctuations in Power Networks (“Flicker”)

Voltage fluctuations are series of voltage changes, or variations of the voltage waveform. The ratio of reactive power to the short circuit capacity is a simplified formula to calculate relative voltage fluctuations at the load end of a High Voltage (HV) supply system.

A changing magnitude in the supply voltage results in a change in the luminous flux of a light source. Therefore the phenomenon is known as “flicker”. Flicker occurs in all kinds of light sources, including incandescent and fluorescent lights. It can significantly impair vision, can be the cause of general discomfort and fatigue, and deteriorates work quality. Voltage fluctuations also have negative influence on induction motors, electrolysers, electro-heat equipment and arc furnaces. They can affect the functionality, energy efficiency and service lifetime of those devices.

This application note describes how voltage fluctuations can be measured and how their source can be located. The latter is often a very difficult task. Mitigating the voltage fluctuations once the source has been located can be equally difficult. Whereas the flicker amplitude depends primarily on the power system itself, the rate of occurrence depends on the type of load and the manner in which it is operated. So far, mitigation measures have focused primarily on limiting the amplitude of voltage fluctuations, and few measures have been taken to alter the load and its operation.

Application Note Author & Publisher: Leonardo ENERGY   

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