Harmonics in power systems

Discussion in 'Power Electronics' started by Cerkit, Jul 22, 2016.

  1. Cerkit

    Thread Starter Active Member

    Jan 4, 2009
    275
    3
    Hi.

    I am desperate to understand how harmonics exist in power systems. I have read over and over about non linear loads and things such as rectifiers and power electronics which switch in and out the current abruptly.

    Intuitively this doesn't help me understand physically what happens especially when most explanations start explaining it through Fourier transforms and decomposition of the frequency spectrum.

    That is all well, my question is, is there a physical interpretation of how the source sine wave of 'F' frequency results in sine waves of multiples of this frequency? If I abruptly switch in and out and draw current at a particular interval of the voltage waveform periodically, as far as I am aware I am still utilizing this current at the same frequency as the source frequency where exactly are these new frequencies being generated from?

    Or are you saying that it can not be viewed physically? It is a mathematical thing that I must just accept?

    Thanks
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,175
    1,798
    The observable part of harmonics in power systems is the distortion in the waveform. It can be shown that non-ideal or distorted waveforms can be decomposed into into sums of sinewaves consisting of a fundamental frequency and an infinite number of harmonics. It can also be shown that each additional harmonic that is added reduces the error between the approximation and the actual waveform.
     
  3. JWHassler

    Member

    Sep 25, 2013
    201
    33
    The demonstration that got me to accept it was the addition of sines to make a square wave
     
    Kjeldgaard, nsaspook and Sinus23 like this.
  4. Papabravo

    Expert

    Feb 24, 2006
    10,175
    1,798
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