EFFECTS OF HARMONICS IN POWER SYSTEM BASICS AND TUTORIALS

The effects of harmonics are described here only in the context of the analytical harmonic system study, details of these effects can be found in referenced literature. IEEE Std 519-1992 (Chapter 6) and Prabhakara, Smith, and Stratford [B30] (Chapter 5) deal with the subject in detail.

The effects of harmonics in a power system are pervasive in that they influence system losses, system operation, and system performance. Unless the harmonics are controlled to acceptable limits, the power equipment and, even more so, the electronic equipment may be damaged resulting in and costly system outages.

The effects of harmonics are due to both current and voltage, although current-produced effects are more likely to be seen in day-to-day performance. Voltage effects are more likely to degrade the insulation and hence shorten the life of the equipment.

The following describes some of the common effects of harmonics:

a) Increased losses within the equipment and associated cables, lines, etc.,

b) Pulsating and reduced torque in rotating equipment,

c) Premature aging due to increased stress in the equipment insulation,

d) Increased audible noise from rotating and static equipment,

e) Misoperation of equipment sensitive to waveforms,

f) Substantial amplification of currents and voltages due to resonances, and

g) Communication interference due to inductive coupling between power and communication
circuits.

Generally, harmonic studies involving harmonic flows and filter design do not involve detailed analysis of the effects of harmonics if the limits imposed by the user or by a standard are met.

However, in specific cases, analysis of harmonics penetrating into rotating equipment, causing relay misoperation, or interfering with communication circuits may require a separate study.

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