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sidhu16
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Power system harmonics

03/06/2010 12:57 AM

I'd like to study on Power system harmonics. Specifically want to know about how do Harmonics get generated and how can harmonics be eliminated from the system? Pls provide me link of some literature alongwith your answers.
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Anonymous Poster
#1

Re: Power system harmonics

03/06/2010 1:07 AM

Creation:

Switching.

reactive elements (including the self reactances)

Non linear loads

Surges (as lightning)

Faults

Elimination

- Filters/ reactors

- Surge arrestors

Literature

- there are several text books on this aspect.

- Google search.

Results 1 - 10 of about 2,360,000 for power system harmonics. (0.13 seconds)
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msamad
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#2
In reply to #1

Re: Power system harmonics

03/07/2010 9:52 PM

There are thousands of links that show up in Google search for power system harmonics (as the Guest indicated); only a few are the good documents for the beginners to understand. Here are the links for some of the good ones I found. The last one is more elaborate and mathematical but it is the best one. In fact, the concept of harmonics comes from the mathematics 'Fourier Series'. So, the better understanding of harmonics requires the good concept of 'Fourier Series'. Chapter 2 of the last link goes into detail about it.

https://www.rose-hulman.edu/class/ee/HTML/ECE471/PDFs/Lect15.pdf

https://www.we-energies.com/business/energyeff/harmonics.pdf

https://www.powerstudies.com/articles/Harm_Intro.pdf

http://www.wmea.net/Technical%20Papers/Power%20System%20Harmonics.pdf

The method for measuring the harmonics is some kind of confusing, especially to beginners, because there are three different methods used for measuring the harmonics. The three methods are:

(1) Crest Factor (CF): Ratio of the Peak of wave form to the rms of wave form; a true sine wave has its value 1.414. A wave having the CF less than 1.414 tends to be flat-tapped, while a CF greater than 1.414 indicates a voltage that tends to be pointy. CF is also called Peak Factor. This method is generally used for the measuring of harmonics contained in the UPS output.

(2) Total Harmonic Distortion (THD): The total harmonic distortion is the square root of the sum of the squares of the harmonic voltages divided by the fundamental voltage. A true sinusoidal wave has a value of 0. This method is used for measuring the harmonics introduced by the non-linear loads in power system.

(3) K-Factor: A weighting of the harmonic load currents according to their effects on transformer heating. A K-factor of 1 indicates a linear load (no harmonics), while K-factor 20 indicates a large amount of harmonic content. This method is used to measure the thermal effect of harmonics on transformers.

- MS

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shanbhag
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#3

Re: Power system harmonics

03/07/2010 11:57 PM

Dear Sidhu,

Please check www.epcos.com and go to application guides. I too have got a lot of knowledge from that site. Epcos is manufacturer of capacitors and reactors and they have done a lot of research and provided solutions worldwide.

Thanks
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shanbhag
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#4

Re: Power system harmonics

03/08/2010 1:12 AM

Dear Sidhu,

Mail me at shanbhag@sequentindia.com. i have a report on harmonic analysis which was recently carried out by our company.

thanks
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Qqberci
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#5

Re: Power system harmonics

03/08/2010 11:39 AM

I would say the most common harmonic sources on the power lines are the rectifiers, the cheap switching power supplies and the over-excited/overloaded transformers. There was a very good summary in the EDN in 1991, 11 April issue. If you need it, I can scan and send it.

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shekhar kadam
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Posts: 14
#6

Re: Power system harmonics

03/08/2010 11:38 PM

MAJOR SOURCE OF HARMONICS IS NONLINEAR LOAD LIKE WELDING,INDUCTION FURNACES,VARIABLE FREQUENCY DRIVES ETC.

HARMONICS CAN BE ELIMINATED BY ACTIVE FILTERATION OR PASSIVE FILTERATION METHODS .BOTH METHODS HAVE THEIR OWN AND MERITS AND DEMERITS.

ALTHOUGH LOT OF INFORMATION IS AVAILABLE ON WEB U HAVE TO START IT FROM BASICS .UNDERSTAND WHAT IT IS ? HOW ACTUALLY IT IS GENERATED?WHO GENERATES?THEROTICALLY HOW IT CAN BE AVOIDED?PRACTICAL WAYS OF ELIMINATING IT.IF YOU ARE BEGINER GO STEP BY STEP OTHERWISE U WILL CONFUSE.
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loadshare
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#7

Re: Power system harmonics

03/13/2011 1:22 AM

nice info

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dhayanandhan
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#8

Re: Power system harmonics

12/08/2012 1:05 PM

Dear Mr. SIDHU16,

Elimination of HARMONICS, technically possible, but will be QUITE EXPENSIVE. So HARMONICS is to be controlled and hence it depends how much investment is to be made is also a deciding factor.

For example 12 PULSE VFD will be more costlier (the HARMONICS CONTROL will be very good) than 6 PULSE VFD where HARMONICS WILL BE HIGHER and dissipated as HEAT, thus LOSS OF ENERGY.

Pl.refer Hand Books and Text BOOKS and you will get more details.

DHAYANANDHAN.S
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