10/01/2020

What is Harmonics? Its Generation & Effect on Power System

Harmonics
  • The harmonics are defined as the component of signal whose frequency is integral multiple of fundamental frequency.

Fundamental frequency and harmonics

Fundamental frequency
Third harmonics
Fifth harmonics
Seventh harmonics
Ninth harmonics
50 Hz
50 × 3 = 150 Hz
50 × 5 = 250 Hz
50 × 7 = 550 Hz
50 × 9 = 450 Hz

fundamental-harmonics

Generation of Harmonics by Non Linear Load
Effect of Harmonics
( 1 ) Power electronics kit  
  • Mal functioning
( 2 ) Power Capacitors
  • High current, failure due to load
( 3 ) Transformer / Switchgear equipment
  • Power losses
  • Over heating
  • Higher power consumption
  • Neutral overloading due to triple harmonics
( 4 ) Rotating machines
  • Higher power losses
  • Pulsating torque due to negative phase sequence current
  • Higher frequency current increase cable resistance due to skin effect , finally it increases over heating
( 5 ) Relays
  • False tripping
Types of harmonics
  • Current harmonics
  • Voltage harmonics
How to reduce harmonics or harmonics mitigation?
The harmonic mitigation is done by harmonic filters. There are following types of harmonic filters
  • Active filter
  • Passive filter
  • Hybrid filter
You may also like :

No comments:

Post a comment