Comments on: Harmonic filter for better power quality

By: nadia

nadia — Sun, 14 Mar 2010 17:18:46 +0000

hello..i’m admired your knowledge in power quality problem..i’m doing my project to eliminate the harmonic,but still in progress since the circuit is not well design.may i know how to design a simulation of single phase active power filter that use IGBT as an inverter, and how to control the IGBT,I’ve inject pulse generator to control IGBT but it’s still not succeed.my simulation run using matlab/simulink.will you help me to solve this problem?i really need your attention..this my email nadya_mon87@yahoo.com

By: raed odeh

raed odeh — Fri, 18 Dec 2009 01:47:09 +0000

Hi Cobus,
You would porpably need to connect your caps in delta. This decuple the caps from the triplens.
As for the reactor , you need to select a tunning order where the cap/reactor will provide lowest impedance at that order. for instance we tune our filter to 3.7 order. This order will not interfer with utility ripple signal and will decuple the caps from anything higher than 5th order. This will only work when voltage distortion is around 7%. Above that you need to mannage the harmonics via a tuned filter .usually around 5-7 order thus removing almost 80% of the harmonics in the system. The issue with this type of filter is you need to make sure the filter can abosrb all harmonic currents without overloading the caps. The cap will only take 130% of its rated current before it starts to e fail,hence you may need to address the amount of harmonic current in the netwrok then size a filter accordingly. The kvar value of the all the filters will contribute to reactive compenstaion . This is very cruical in defining the correct way to control the filter. The easiest option is to install an Active filter at the main LV borad and allow it to run in PF/ harmonic mode. you hit 2 birds in one stone and you donot have to worry about resonance.

By: Do you believe in Jevons Paradox? - Page 6 - PriusChat Forums

Do you believe in Jevons Paradox? - Page 6 - PriusChat Forums — Mon, 09 Nov 2009 21:40:27 +0000

[...] the line side. Note that these harmonics are not necessarily present on the LOAD side of the UPS Harmonic filter for better power quality | Electrical engineering BLOG If the UPS is a commercial model (A FCC Part 15 Class A rating) it can also cause significant [...]

By: Jim Johnson

Jim Johnson — Sun, 18 Oct 2009 23:27:56 +0000

Hi, Corbus,

Sorry for the late reply. Got a little busy and failed to go back to my notice from the blog.

The thyristor rectifier is the most rugged, most dependable, and easiest to control rectifier on the market. It is also the least cost. No one has spent time, that I know of, in developing a different method.

Regards, Jim

By: anil

anil — Sun, 18 Oct 2009 18:28:56 +0000

the paper is excellent but i want full information about the topic .can u give me please??????
my email id is anil05.perala@gmail.com

By: suyog

suyog — Tue, 22 Sep 2009 07:16:32 +0000

i am suyog from bhopal i am preparing a major porject. so please tell me circuit diagram of Harmonic filter for better power quality.

By: Er.parmjit Singh

Er.parmjit Singh — Tue, 15 Sep 2009 11:47:08 +0000

i am parmjit from daviet. we are making a major porject. so pleace tell me circuit diagram of Harmonic filter for better power quality.
i am very thank full to you.

By: Cobus Verster

Cobus Verster — Thu, 03 Sep 2009 07:04:02 +0000

Jim
Is there a much better rectifier system for plating plants other than SCR control, which will have zero or very little harmonic distortion contribution to the system?
Cobus

By: Cobus Verster

Cobus Verster — Fri, 28 Aug 2009 08:19:50 +0000

Jim,
I have questions for you regarding the selection and design of harmonics filters. If I have a 400/440 Volt 3 phase 40kVar capacitor bank in a Powerfactor system which needs to be protected against 3rd to 13th harmonics of various amplitudes, how do I choose the inductance or Xl for each leg of the 3 phase supply to the capacitor? My concern is resonance at some of the harmonic frequencies obviously, as well as the internal heat in the inductor/filter and the voltage drop accross the inductor at the base frequency of 50Hz, because that will reduce the capacitors effective kVar slightly.
Then I also wish to know if I can use tuned filters for each harmonic in a smaller inductor/filter design inside the various machines where the harmonics are being generated and if it is a good idea, what must I bear in mind, or do I rather block the harmonics in a machine with a local inductor/filter designed for the machine and what about voltage drop and heat?
Regards

By: Jim Johnson

Jim Johnson — Mon, 24 Aug 2009 19:59:02 +0000

Hi, Cobus,

The reason harmonics are a topic is because semiconductor technlogy is being used for energy savings in all types of applications. New washng machines employ a variable frequency drive and digital logic. They have eliminated the mechanical gear box for a direct coupled motor. It is more efficient. Also, all electronic products employ AC to DC rectifiers. Switched mode power supplies (SMPS) are everywhere. As time passes more of these nonlinear loads will employ their own harmonic mitigation methods. But design evolution takes time.

In the mean time, solutions are offered in many varities. Depending upon the type of loads and the concentration of those loads on any given network the solutions vary widely. I am not familiar with the South African market, so I don’t know who might be able to help you. Shaun Wilson at shaun.wilson@za.schneider-electric.com is one contact I do know who may be able to assist.

Harmonics is called ‘imaginary’ or reactive current in electrical engineering. It does not do work but permits work to be done. This is the same definition applied to reactive current that is phase shifted from the fundamental current (Cos phi). There is no known way to capture this power and reuse it for real work.

Regards, Jim