TABLE OF CONTENTS The term power quality refers to the purity of the voltage and current waveform, and a power quality disturbance is a deviation from the pure sinusoidal form. Harmonics superimposed on the fundamental are one cause of such deviations, and this chapter describes the nature, generation and effects of harmonics on power supply systems, together with the limitation of such effects and harmonic studies.
The widespread and increasing use of solid state devices in power systems is leading to escalating ambient harmonic levels in public electricity supply systems.
These harmonic levels are subject to limitations in order to safeguard consumers plant and installations against overheating and overvoltages. It is also incumbent upon individual consumers to ensure that their equipment does not produce harmonic levels that exceed such limits at the point of common coupling with other consumers. These are called emission limits . Immunity standards set down the disturbance levels which equipment should be capable of tolerating without undue damage or loss of function. A third set of standards, for compatibility levels has the function of enabling co-ordination and coherence of the emission and immunity standards (see Table 24.3).
| Term | Explanation |
|---|---|
| Planning level | Level of harmonic distortion that can be used for planning purposes in evaluating the impact on the supply system of all consumer loads. They are set by the utility and can be considered as internal quality objectives. They are equal to or lower that compatibility... |
