Power grid and disturbances
Voltage quality - Introduction

For an energy network, four main disturbances and their possible combinations are identified.

• Amplitude variations

  These are not the slow variations in voltage that are corrected by the transformer's on-load regulators, but rapid variations in voltage, in the form of voltage dips or sudden jolts, either isolated or more or less repetitive, regular (square-wave) or irregular.

• Voltage waveform changes

  The wave is no longer sinusoidal and can be considered as the superposition of a wave with a fundamental frequency of 50 Hz, harmonic voltages whose frequency is an integer multiple of the fundamental frequency, and interharmonic voltages at any frequency.

• Three-phase system asymmetry...