Detect and eliminate harmonics: why?: Difference between revisions

Revision as of 14:51, 18 October 2013

Harmonic disturbances

Harmonics flowing in distribution networks represent disturbances in the flow of electricity. The quality of electrical power is deteriorated, and the efficiency of the system is decreased.

Here are the main risks linked to harmonics:

Overload of distribution networks due to the increase of r.m.s. currents,
Overload of neutral conductors, which current can exceed the phase currents,
Overload, vibration and premature ageing of generators, transformers and motors as well as increased transformer hum,
Overload and premature ageing of Power Factor Correction capacitors,
Distortion of the supply voltage that can disturb sensitive loads,
Disturbance in communication networks and telephone lines.

Economic impact of disturbances

All these disturbances have an economic impact:

Premature ageing of equipment means it must be replaced sooner, unless oversized right from the start,
Overload on the distribution network means higher equipment rating, increased subscribed power level for the industrial customer, and increased power losses,
Unexpected current distortion can lead to nuisance tripping and production halt.

A necessary concern for the design and management of electrical installations

Harmonics are the result of the always expanding number of power electronic devices. They have become abundant today because of their capabilities for precise process control and energy saving benefits. Typical examples are Variable Speed Drives in the Industry, and Compact Fluorescent Lamps in commercial and residential areas.

International standards have been published in order to help the designers of equipment and installations. Harmonic emission limits have been set, so that no unexpected and negative impact of harmonics should be encountered. In parallel to a better understanding of effects, solutions have been developed by the Industry.

Harmonic consideration is now a full part of the design of electrical installations.

@@ Line 1: / Line 1: @@
 {{Menu_Harmonic_management}}
-'''Disturbances caused by harmonics'''
-Harmonics flowing in distribution networks downgrade the quality of electrical power. This can have a number of negative effects:
+== Harmonic disturbances ==
-*Overloads on distribution networks due to the increase in rms current
+Harmonics flowing in distribution networks represent disturbances in the flow of electricity. The quality of electrical power is deteriorated, and the efficiency of the system is decreased.
-*Overloads in neutral conductors due to the cumulative increase in third-order harmonics created by single-phase loads
-*Overloads, vibration and premature ageing of generators, transformers and motors as well as increased transformer hum
-*Overloads and premature ageing of power-factor correction capacitors
-*Distortion of the supply voltage that can disturb sensitive loads
-*Disturbances in communication networks and on telephone lines
-'''Economic impact of disturbances'''
+Here are the main risks linked to harmonics:
+* Overload of distribution networks due to the increase of r.m.s. currents,
+* Overload of neutral conductors, which current can exceed the phase currents,
+* Overload, vibration and premature ageing of generators, transformers and motors as well as increased transformer hum,
+* Overload and premature ageing of Power Factor Correction capacitors,
+* Distortion of the supply voltage that can disturb sensitive loads,
+* Disturbance in communication networks and telephone lines.
-Harmonics have a major economic impact:
-*Premature ageing of equipment means it must be replaced sooner unless oversized right from the start
+== Economic impact of disturbances ==
-*Overloads on the distribution network can require higher subscribed power levels and increase losses
-*Distortion of current waveforms provokes nuisance tripping that can stop production
-'''Increasingly serious consequences'''
+All these disturbances have an economic impact:
+* Premature ageing of equipment means it must be replaced sooner, unless oversized right from the start,
+* Overload on the distribution network means higher equipment rating, increased subscribed power level for the industrial customer, and increased power losses,
+* Unexpected current distortion can lead to nuisance tripping and production halt.
-Only ten years ago, harmonics were not yet considered a real problem because their effects on distribution networks were generally minor. However, the massive introduction of power electronics in equipment has made the phenomenon far more serious in all sectors of economic activity.
-In addition, the equipment causing the harmonics is often vital to the company or organisation.
+== A necessary concern for the design and management of electrical installations ==
-'''Which harmonics must be measured and eliminated?'''
+Harmonics are the result of the always expanding number of power electronic devices. They have become abundant today because of their capabilities for precise process control and energy saving benefits. Typical examples are Variable Speed Drives in the Industry, and Compact Fluorescent Lamps in commercial and residential areas.
-The most frequently encountered harmonics in three-phase distribution networks are the odd orders. Harmonic amplitudes normally decrease as the frequency increases. Above order 50, harmonics are negligible and measurements are no longer meaningful. Sufficiently accurate measurements are obtained by measuring harmonics up to order 30.
+International standards have been published in order to help the designers of equipment and installations. Harmonic emission limits have been set, so that no unexpected and negative impact of harmonics should be encountered. In parallel to
+a better understanding of effects, solutions have been developed by the Industry.
-Utilities monitor harmonic orders 3, 5, 7, 11 and 13. Generally speaking, harmonic conditioning of the lowest orders (up to 13) is sufficient. More comprehensive conditioning takes into account harmonic orders up to 25.
+Harmonic consideration is now a full part of the design of electrical installations.
-[[ru:Зачем нужно обнаруживать и устранять гармоники?]]
-[[zh:检测和减少谐波：为什么？]]

Detect and eliminate harmonics: why?: Difference between revisions

Revision as of 14:51, 18 October 2013

Harmonic disturbances

Economic impact of disturbances

A necessary concern for the design and management of electrical installations

About this wiki

Help

Navigation