Electrical Power System Harmonics Explained
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- Опубліковано 14 жов 2024
- This video is based on material from Jim Phillips Power Systems Engineering live stream course brainfiller.co...
In this video, Jim answers the question, “What Are Harmonics?”
What are harmonics and how do they get into the power system? Electrical power system harmonics are multiples of a fundamental frequency typically 60 Hz. or 50 Hz. Jim walks you through multiple harmonic wave graphs and the math of harmonics and frequency overlay and some of the distortion that can occur. Six-pulse waveform has a lot of different harmonics that make it up based on certain types of loads. Like certain types of drives, rectifiers, resulting in the input current resembling as if it’s pulsed in six separate pulses instead of a clean sine wave. Jim then goes into a diagram explanation of harmonics analysis. The way that most harmonics get into the power system is the load, if you have a load that is distorting, or pulsing, or changing the characteristic of a current, that current can be rich in harmonics.
Non-linear loads are the biggest source of harmonics that can create serious problems on an electrical system. Learn more: brainfiller.co....
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Thank you Jim! This really just explained everything. I (17) am currently an exchange student in Germany, and its hard for me to understand everything that the teacher says. Videos like this are rare. I have a test tomorrow, wish me luck Jim!
Aaron Kamalkhani I am glad you found the video helpful. I wish you well on your test tomorrow.
You sir, are an excellent explainer of things.
Simple and to the point!
Thanks !! How to Create a Six-Pulse Waveform ?
very interesting subject with all the inverters going on the grid.. wind, solar, ac motor-inverters, electric vehicle large battery charger inverters... dirty power, burn-outs. thanks...:)
Great video this! Straight to the point!
Beautifully explained, thank you
very beautifully explained .thankyou sir
great video, thank you!
Could you use harmonics to stabilise electromagnetic energy? Or a field?
Fantastic sir!! Bless you.
Would you happen to have any information on the workings of harmonics and spurious transmissions together?
How we can say that the load is actually causing a perfect 5th or 7th harmonic?
There are a couple of ways to determine the harmonics being produced by a load.
1) is to measure the specific load with a harmonic meter. The measurements will show which harmonics are there.
2) Computer simulations performed before equipment is installed may use one of several different models depending on the load. For example, loads with 6, 12, 18 pulse equipment create a predictable pattern of harmonics.
Most harmonic software has these models as part of their modeling software. Great question!
i was looking for harmonics relative to a song on guitar, and now my brain has flashburn.
Supoose if the load was continuously changing and it was becoming the cause of 5th harmonic now lets suppose if the load is turned off where will go that superimposed 5th hormonics based wave shape?
When the harmonic producing load is switched off, the harmonics go away. Harmonics are treated as a constant current source based on the load (and the load being on) The design of harmonic filters (if used) need to take this into account.
The most complex design I was involved with was in the 1980's (yes a few years under my belt) It was a large arc furnace for steel production. The arcing was creating harmonics and voltage flicker back at the utility substation. lt was like hitting a moving target since the magnitude and harmonic order kept changing with the random arcing of the furnace.
The solution involved designing and constructing a static var compensator (SVC) This is a capacitor bank with thyristor controlled reactors in series and the compensation would change on a cycle by cycle basis. (probably more than you cared to know but since we were on the subject....)
Thanks for the question!
what is the precentage on the waves (39%)?
If I have a 10MHZ signal that is meant to be a system clock, how will harmonics affect it if i know the 10mhz will keep its signal characteristics through out the system?
What does he mean about the 5th harmonic? Why are they numbered?
They are numbered to identify which harmonic frequency. They are based on a "fundamental" frequency for power systems that is 50 or 60 Hz. The 5th harmonic is a frequency of 5 x 60 Hz or 300 Hz. Thanks for watching. - Jim
Think of a guitar string. Pluck that particular open string; that’s the fundamental frequency (1st harmonic).
Now place your finger tip exactly at the mid point to divide the string in half (do not depress the string, just place fingertip there) pluck again.. that pitch frequently is the 2nd harmonic.. next divide the string in 3rds, 4ths, 5ths, etc.. the subdivision of the length is where the harmonic nodes live. The frequency multiplies with each wavelength subdivision because the wave gets shorter, hence higher frequency. This happens naturally. God’s design! 🤓
thank you sir
You are quite welcome!
Thanks
great explanation!
Dear sir I have some question to ask you. I would like to ask you about industrial MV capacitor bank. I would like to write my thesis related to MV capacitor bank that install at 'Tiger beer brewery limited'. I would like to ask some recommendation or do you have some documents related to MV capacitor bank? Could you send it to me? What step that i should follow? What kind of methodology or procedure? Does detuned reactor function both as filter and irrush current limited?
Best regard
SUOY Bunheng
A question (perhaps a dumb one, I don't know):
Why only consider waves of harmonic frequencies? Surely waves of all frequencies that are somehow introduced by loads will act to distort the main signal? Is it just because it makes it easier to do the maths?
I get that the harmonic ones will be 'worse' as their peaks/troughs are in sync with the main ones peak. But surely all frequency signals will also have a large effect? What am I not getting?
The part you're not getting is "Even Harmonics", for a reason. Surely you are wrong about all frequency signals having a large effect.
In Korea they do their math Gangnam Style.
After you've done your math Fourier Style in detail (referred to in this video ) you will confirm whether your question is a dumb one, or not. Please let us know what you found out as an ode to Socrates.
Good question. The primary cause of power system harmonics is the characteristic of the load where the current is non-linear often due to SCR's, diodes and other switching devices. Most loads like drives, 3 phase UPS etc. have a predictable pattern that is made up of odd harmonics, and not all odds are included.
Even harmonics can exist but are not as common. They will skew the wave shape left or right giving it an asymmetrical shape about the axis (90 degrees and 270 degrees) Even harmonics are sometimes an indication that there is a problem with the load, i.e. diode, SCR etc.
I have also measured non-integer harmonics in the past which can be from a "random" load characteristic such as an electric arc furnace. These types of loads have such an erratic current from the arcing that the harmonic content is continually changing and include non-integers such as 4.3, 5.1 7.6 etc. Those numbers that I listed are random examples - the actual harmonics are all over the map for a furnace.
Thanks a million, sir :)
thanks , is great
Glad you like it!
Well, saying "harmonics are a multiple of the fundamental frequency" doesn't make much sense. A more accurate definition would be "harmonics are sinusoids *whose frequency* is an integer multiple of the fundamental frequency".
Professor, what could cause them in, and why do they matter?
Harmonics are mostly from what are known as non-linear loads. i.e. loads that distort the current such as inverters, motor drives etc. Distorted current can increase the heat and result to thermal degradation. When significant harmonics are present, they can result in voltage distortion. The situation becomes worse if there are capacitors on the system. The power system behaves as mostly inductive but with capacitance, it now behaves like an LC circuit with resonance. If a harmonic frequency is on or near a resonance frequency, there can be a whole array of problem, overheating, equipment misoperation, failures etc.
oh ok, so let say, l may be having some issues related to this harmonics affecting my Computer and monitor, if l plug them to a generic ups that has solve it right?
so would you say harmonics are not ever used on purpose, they are the result of a distorted component causing the harmonic?
well, not in electricity, but in Music they are used on purpose :P
how we can check the hormonics using the power world software
Software for harmonic modeling is to create predictive models and you would want to consult the software companies. Software for evaluating measurements, requires measurement equipment.
In other words; the resulting waveform due to the effects of the load???
Yes. Loads like VFD's distort the current which results in the additional frequencies.
thank you
A meter would show a distorted waveform but would not indicate which harmonics. There are certain signature wave shapes that are an indicator of specific harmonics. As an example a sine wave that is flattened on top is usually the result of a 3rd harmonic component.
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