Circuit diagram of an active power filter

In summary, a research project is in need of a circuit diagram for an active power filter to mitigate harmonic current in an induction furnace. The challenge is not so much the power electronics circuit - but developing controls that will work reliably.
  • #1
slog
5
0
Hi
Is anybody in the house that can help with circuit diagram of an active power filter for mitigating harmonic current.
 
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  • #2
A little context will help. Freq, current, voltage etc.
 
  • #3
@yungman, can you please shed more light on your comment?
 
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  • #4
slog said:
Hi
Is anybody in the house that can help with circuit diagram of an active power filter for mitigating harmonic current.
Describe your needs, the origin of the harmonics, and whatever else is relevant. Is this a homework exercise?
 
  • #5
simplest one i ever saw was a series tuned LC for 180 hz (3rd harmonic of 60HZ) to clean up inverter output..
 
  • #6
@all tanks so much. I ve a research I'm working on, it's all about a induction furnaces in a steel company inducing harmonic current back to the line. I am trying to develop an active filter to mitigate the harmonic current in the line. so I'm in need of active power filter circuit diagram that will help to reduce such effect on the line.
 
  • #7
Do a search on ieee.org, google scholar or similar with the keywords active filer, induction furnace, harmonics and you will see that this topic of research has been well discussed. Many different topologies and control strategies have been proposed. For detailed discussion on basic inverter/filer topologies you may need to consult a book on power electronics.

Research builds often/mostly/every time on previously work. If you don't know of these papers you may waste your time re-inventing the wheel.
 
  • #8
The answer will also depend on the type of induction furnace - if it is a line frequency furnace - filtering may be the only option and active filter is advised as the current harmonics change with load and material types. For a higher frequency furnace you are typically rectifying the line and then making the output current with IGBTs or other system - here it may be better to look into an active rectifier.
In ether case the challenge is not so much the power electronics circuit - but developing controls that will work reliably - so this not something that I would advise as a one off solution.
To properly apply ether / any solution I would advise a power study - typically done by connecting a Power Quality Analyzer to the system for a few weeks to evaluate the range of harmonics and possibly PF issues - a solution can then be sized around that data. The biggest problems I have seen in large scale filtering ( Static, Switched and Active) is a lack of up front analysis - leading to oversize or slow responding systems - that then cause system wide disturbances.
 
  • #9
@Windadct, please do you know any theoretical method i can use to calculate the harmonic current instead of using power quality analyser as ealier suggested. the following are the specification of the furnace: 1. Equipment type:KGPS600-0.8
2. Rated input voltage: 380V;
3. frequency of input current:50/60HZ;
4. 3相;phases of input power: 3 phases
Rated input current:960A(270mm2 copper cable recommended )
5. Rated output power 600KW
6. Rated output frequency 0.8KHZ±20%;
7. Rated output voltage : 1500V
8. Output phase: 1 phase
9. Rated capacity : 1 metric ton
10. melting time: 1.0MT/Hout
11. Cooling water consumption:18TON / Hour
12. electricity power supply(recommend): 600KVA
Thanks.
 
  • #10
Hello Slog... Sorry for the delay, there is really no way to predict this, you need to know a lot more about the design of the device as well as about the power system it is connected to. The chap way to build these is with just a rectifier front end with minimal to no built in filtering- here in the US you would not be able to use this - 600KW/960A with no filtering - Ill bet you have over 100-200A harmonic current - really a mess.

At this power level - I really can not comprehend trying to do this on the cheap.
 
  • #11
@windact, thanks alot. i appreciate you. The problem with my research is just that the company i intend to use are not allowing me into company. i need to obtain subsequent harmonic currents and voltages from the above fundamental current and voltage, can you please out. thanks
 
  • #12
If a supplier can not / will not say how bad the harmonics are - look for another supplier - the active filter that can accommodate this will cost more than buying a better system to start with.
 
  • #13
You're asking people to guess about something they've never seen.

It's going to have to be measured.
I have used these before with osciloscope or spectrum analyzer.
http://www.grainger.com/Grainger/FLUKE-AC-Clamp-On-Current-Probe-2HZC5 [Broken]

2HZC5_AS01?$productdetail$.jpg

(credit to Grainger for the picture...)

How is it powered? A delta connected three phase transformer will absorb a lot of third harmonic. Ask their electricians about what feeds it.
 
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1. What is an active power filter?

An active power filter is an electronic device used to correct the power quality in electrical systems by actively controlling the flow of current and removing harmonics and other disturbances from the power supply.

2. What is the purpose of a circuit diagram in an active power filter?

The circuit diagram of an active power filter provides a visual representation of the components and connections within the device. It helps engineers and technicians understand the functionality and design of the filter, making it easier to troubleshoot and make modifications.

3. What are the essential components in an active power filter circuit diagram?

The main components in an active power filter circuit diagram include a control unit, power electronics, sensors, and a filtering circuit. The control unit uses feedback from the sensors to adjust the power electronics, which in turn filters out unwanted harmonics and disturbances.

4. How does an active power filter work?

An active power filter works by sensing the electrical current in a system and comparing it to a reference signal. The control unit then calculates the necessary compensation needed to filter out any disturbances and sends commands to the power electronics to adjust accordingly. This process is repeated continuously to maintain a stable and clean power supply.

5. What are the benefits of using an active power filter?

An active power filter can improve the power quality in electrical systems by reducing harmonics, voltage fluctuations, and other disturbances. This can lead to increased energy efficiency, improved equipment performance, and reduced downtime and maintenance costs. It also helps to comply with regulatory standards for power quality and reduce the risk of electrical failures and damage to sensitive equipment.

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