Performance of Matrix Harmonic Filters - for the eyes of Drive Experts 11

[edison123]

In another thread, jbartos referred an interesting article by MTE corp about the performance of the Matrix Harmonic Filter (with 6 pulse rectifier) claiming it to be the best bet as compared to 12/18 pulse rectifiers with line reactors for harmonic reduction.

The article can be downloaded/read at (thx to jb)

http://www.mtecorp.com/mitigation.pdf

I am interested to know from end users/drive experts whether all that is claimed in this article is true enough; or it is just a hard sell rubbishing competitors.

 

[ICEMAN]

Re the last posting from 'jbartos'.

I agree that AFE drives can and are purchased for harmonic attenutation purposes only. What I was trying to say was that there are far more cost effective ways of reaching ~5% Ithd than AFE. The EMI issue is a major one too. Maybe in North America EMC (electro-magnetic compatibility) is not really an issue but in Europe and most other parts of the world it is. Reliability is far better than in mid 90's when I was involved in a UAE project with AFE drives (mentioned in my last reply but is still a consideration). All three are very valid reasons to look at all the drive harmonic options.

Lineator in the Mirus brochure is only to 1500HP I agree but the range and designs are available for excess of 2500kW/3300HP. I know that for sure. In addition, some major drive companies (one being ABB) are looking to Mirus for MV versions of the device (up to 6.6kV) which would take it range based on current designs up to around 10MW/13,400HP. I beleive, but don't quote me that they are looking right now to build an MV Lineator for a test site. I'm sure if any other drive companies are interested in MV Lineators Mirus would be happy to talk to them.

As you said there are a number of applications suitable for AFE drive (or DC 4 quadrant drives) but at best that is less than 13% of the globla drives market. The biggest share (68%) is for centrifugal pump and fan applications. (Talking about these I dropped a boo-boo yesterday re harmonics and square law loads - I meant to say that the harmonic currents reduce approx with the cube of speed (not load).

The other thing with Lineator I notice is that it also acts as an EMI filter for the drive. Not as good as you get with dedicated EMC filters (which often cost almost as much as the drive) but makes a big difference on AM radio interference problems.

ICEMAN

P.S. How come nobody taken up my challange yet regarding DUPLEX REACTORS ? Do I assume nobody has heard of these ?

 

[NNG]

Dear Iceman,
No doubt that those filters are the simplest and affordable topologies but we have a right question about them: Performance of Matrix Harmonic Filters - for the eyes of Drive Experts
As a passive harmonic filters the “Lineator” and “Matrix” have a similar configuration called a “broad band filter” that provides a low impedance trap for the harmonics around the 5th and 7th (a major harmonic content of the Drive). The Lineator (Mirus) is that uses mutually coupled reactors while the Matrix (MTE) requires three discrete three-phase reactors using separate cores.
As a lower cost solution for harmonic mitigation in drives application they still have some weaknesses that occur during their testing:
1. Under no-load conditions, the filters appears capacitive to the power grid and can operate at a 0.95 leading power factor. This causes the line voltage to increase, causing the DC bus voltage of the drive to increase to about 105% of nominal. This should be within the over-voltage limit of the drive but high line voltage will decrease the headroom available before a trip occurs.
2. When operating on a generator back-up system, this leading power factor can also present a problem for the generator’s voltage regulator causing unstable operation.
3. When operating at full load, the DC bus voltage of the drive will decrease to about 96% of nominal. This limits the ability of the drive to provide full speed, full voltage at full load to the motor. Instead, the motor will be operating at a reduced magnetic field, with more slip, causing it to draw more current and run hotter. Rated RPM will not be achieved. Max RPM will be closer to 92% of rated. This can be critical for several pump applications.
4. We have found that the SCR firing control used on a converter of the drives when connected to a Lineator, does not operate as designed, and will experience over-voltages and trips. The Lineator is not recommended for use on these drives for this reason. Drives with a simple diode bridge converter do not experience these problems.
5. Mirus can only guarantee that the Lineator will reduce the line current THD to less than 8% under full load. Worst case conditions as stated in IEEE std 519-1992 requires less that 5% current distortion. It may be acceptable under some applications, but not all.
Thank you, NNG.

 

[jbartos]

Comments:
1. In-line or series passive harmonic filters experience voltage drop. This can be compensated a "boost" transformer or autotransformer.
2. The SCR firing circuits have to be supply for a better quality power supply.
3. When it comes to LINEATOR operation with the generator, the mutual electrical coexistence will depend on the mutual sizes, e.g. 100HP LINEATOR will not affect 1MW generator significantly.

 

[ICEMAN]

Well NNG. At last a guy on the way to knowing what he is talking about ! Well done.

1. I can agree that at no load the Lineator does represent a small ~3% voltage rise as seen from the drive. That is well within normal tolerance and diminshes with load. I am advised that the new Advanced Lineator does not have any volt rise at no or light load. Obviously, the Mirus guys took this on board.

2.What actual real (not just theorical) experience have you got with Lineator on generators. I do not know of any AVR or related problems due to leading cos phi due to Lineator. Do you know of any ?

3. The Lineator does not just 'trap' the 5th and 7th harmonics. To mu knowledge it attenuates all 6n+/-1 harmonics up to 35th. The Lineator is not a broadband filter as far as I know. If any of the Mirus engineers are reading this maybe you'd like to correct me.

4. Your comment re the voltage drop at full load may be correct (although I believe is not as much as you state) but that is the same magnitude of voltage drop you get with a 3% or 4% reactor which would provide 38-40% Ithd. So what's the problem here ? Are you going to recommend banning AC line reactors from all pump applications (or fans)? Any voltage drop even direct from the mains would result in a similar reduction in torque. You tell me of any product or solution which is perfect.

5. The original design of Lineator was designed for diode or SCR pre-charge front ends. However, some VFDs had strange SCR firing strategies (like the A-B 1336 series) which did not agree with Lineator. However, I am advised that the new Advanced Lineator DOES work with the 1336 Series and similar drives. It has also been tested with a fully controlled SCR bridge (quasi-square wave VFD) and I am told works great. DC drives are now about to be tested also. Go back and try your 'problematic' SCR pre-charge drive with Advanced Lineator - you'll see it works.

You must remember that Lineator is a relatively new and evolving product. Active filters have been around longer !

6. Mirus does only guarantees <8% Ithd (although they state 5-8% Ithd which is the normal range) but even 8% satisfies the majority of drive applications re TDD (read the small print). Afterall, the Vthd of 5% is the more important. From my side I have seen quite a number of installations where the Ithd is less than 5%. I have also seen lots of active filter installations which don't meet the advertised 5% Ithd level.

Anyway, it' been great getting all these comments from you guys re Lineator but how many of you have actually used it or tested it ?

I've give up on asking you guys about Duplex Reactors. I take it nobody has heard of them.

ICEMAN

 

[ICEMAN]

Re NNG's posting....

I have been thinking about your comments re supposed voltage drop of Lineator at full load, overheating motor, not getting to rated speed et al. Now I was a drives guys before I was more involved with harmonics and the norm I found was that the pump's (or fan's)absorbed power (Germans called it 'effective power') was usually around 85% of the installed motor power. So if you take all the inefficiences into account motor (~92% for larger one) and 95% (assuming the VFD matches the motor HP) for the VFD there is still more than sufficient margin there re current and thermal capacity to provide full load (of the pump, for example) at rated speed.

You not agree ?

ICEMAN

 

[NNG]

Dear Iceman,
Why you try to convince me that I am against Matrix and Lineator filters using for drive applications from my view point? I am the same as you as end-user of those products and make my own comments.
Those filters are a chip and simple product and should be used by engineers as they want.
But the customer should be aware about possible problems with their applications too. Not only talking here that New Lineator is the best product I’ve ever seen.
I’m not a designer for Matrix (MTE) or Lineator (Mirus) filters to tell you how they are built (topology). But in my opinion they are still classified as a broad band filter and not a trap filters. Ask MTE and Mirus about their filter configuration and you will see how this works.
I’m not banning AC line reactors from the drive application (with standard impedance 3% or 5%) but from our test we saw the total filter impedance was higher than 5%. The voltage drop on those filters also was presented.
The real environment when your incoming line is + or -10% of nominal (standard drive spec) and soft or stiff power source presented this has effect on a performance of the drive relative to motor.
Through the test we have seen the DC Bus Voltage was dropped to min limit under low incoming voltage line (>-5%) and soft power source and rated drive load.
I think that the both filters still have a capacitor bank in their topologies. So when your drive with those filters will be in stand-by mode the filter capacitor banks are still in circuitry and can absorb the other harmonics that flown in power system. From the test the cap bank current was increasing significant when the loads in system were changed.
The leading power factor also was tested.
Finally, we have to resume that we talking about both filters: Matrix and Lineator. Our mission to share our knowledge and not marketing here for only Lineator product, are you agree?
Thanks, NNG.

 

[jbartos]

Clarification of my previous posting:
2. The SCR firing circuits have to be supplied from a better quality power supply.
This is in the context of LINEATOR versus SCR input side converters AC-DC or AC-AC.

 

[jbartos]

Suggestion: For the Duplex Reactor, visit

http://www.sam-electronics.de/neue_dateien/epg/1.055.pdf

under paragraph "Harmonics"
Essentially, the duplex reactor consists of two reactors in each phase line, one on the input side of the synchronous compensator and one on the output side of the synchronous compensator.

 

[jbartos]

Suggestion: Visit

http://198.173.130.4/main/trench/tr...87256D24001E74EF/$FILE/CorpBrochureCanada.pdf

for a specific information on duplex reactors

 

[ICEMAN]

jbartos..Your link to the site re Duplex Reactors does not work. Can you check it please and ensure it is correct. If not give me more details on who makes it. Thx.

NNG...I agree that our brief is to share our knowledge and not market. Well surprising, from my perspective, that is what I have been doing. I know a lot about Lineator and surrounding issues and took the time to pass that information on via this debate. Maybe you see 'marketing' when I don't necessarily agree with your comments (maybe that's a wee bit strong). To my knowledge everything I have said to date is correct. However, we both have opinions and experiences - perhaps that is why we beg to differ. However, I do respect your opinion and believe you have made a very valueable contribution to this debate. It's only a pity that Mirus nor MTE have joined the debate to answer some of the questions/criticsims/concerned which have been expressed.

In any case nobody should be put off considering either of these products for the attentuation of harmonics on AC drives. However, in experince Lineator (as I have tried to explain in previous contributions) is the far better product.

ICEMAN

P.S. And if I were to choose between calling Lineator a trap filter or a broadband filter I would have to go for the latter. We can agree on that now.

 

[ICEMAN]

How come my postings never give the option of thanking me for my valuable contributions ? Everybody else seems too.

ICEMAN

 

[RalphChristie]

Iceman

It can be useful if you start a new thread re duplex reactors.

Anyway, I've done a quick search on google and found a few websites regarding it. A good looking site - you have to translate it because it is written in German - is:

http://www.schild.net/duplexdrossel/1/

Ralph

 

[ICEMAN]

Ralph

That paper is by Wolfgang Schild who was with Germanische Lloyd in Hamburg. He retired late last year. He was the main man as far as these were concerned.

Duplex reactors have a few drawbacks including the peformance being dependent on the number of generators on line. To date they seem to optimise on two generator scenario. Also, the Vthd on the load side of the reactors is higher than without them fitted (as you have with active filters due to the filter impedance being <1% {i.e. they permit higher harmonic currents to be drawn; ~ 10/15% on three phase and up to 50% on single phase}.

They haven't been used that to date much other than for a number of German research vessels and an cruise ship with ABB cycloconverter drives. They can't be used as far as I see on ships with IT networks (ungrounded neutral) due to the lack of galvanic isolation (to replace the drives EMC filters which cannot be used on IT systems {have to be grounded}. What is used usually are double wound phase shift transformers with copper screen between windings to attentuate the common mode noise for the drive. (Mirus use the TransLineator for this type of application; the transformer for galvanic isolation and Lineator for harmonic mitigation.)

Ralph, why don't you start this new thread on duplex reactor ? It might be a lonely furrow though !

ICE

 

[ICEMAN]

This refers to comments made the other day by NNG....

I have been sent a copy of an independent report on Lineator from a guy in Australia whose company has tested Lineators extensively. I would like to quote a couple of sections which very relevant to our discussions re generator operation, whether Lineator is a broadbank filter and on the voltage drop issue >>>>

1. "The maximum level of reactive power generated by Lineator is about 15% of its rating and therefore leading power factor will not be a problem in general applications.

Note the normal operation of generators is assured when at no load conditions, the level of leading reactive power factor does not exceed 25% of its rating. Even if a Lineator were to be connected to a generator of its own rating, operation would not be influenced."

2. "Note the Lineator is not a so called broadband filter. These filters contain significantly more capacitance than the Lineator, due to the need to compensate for the excessive voltage drop across the series reactance. The effects of power factor associated with broadband filters do not apply to the Lineator."

3. As regards the voltage drop at full load the report further states "With the Lineator in circuit the DC bus voltagis 7-8% higher than without it. With 415V input voltage, the maximum DC bus voltage level is approx. 620-630V, which is well below the overvoltage protection setting.

We have carried out measurements of the DC bus voltage of a standard 6 pulse PWM drive on this particular Lineator and the results are presented in Fig 2.

It is very important to note that the DC bus voltage ripple is significantly reduced with the Lineator. The slightly higher voltage level and reduced ripple level reduce the current drawn by the drive. The result is cooler operation and the drive and it's DC bus capacitors, hence increased reliability of the drive".

The above is word for word from the report. The above statements seem to substaniate my earlier comments re Lineator.

Can I ask if NNG has tested a Lineator or were the tests on generic broadband filters only ?

ICEMAN

 

[NNG]

Dear Iceman,
You are correct. Our tests were done on generic Passive Harmonic Filters including a Lineator.
All of those filters have the same components as L & C but their design arrangement was different.
The notes (1 & 2) from the test report in Australia have a valid information regarding a Lineator. But it may be not applicable for specific situations when I mentioned it in previous posts. Ask those guys how they measured a harmonic current on filter cap bank and input power factor when the tested drive with the filter was in stand-by mode and other loads (preferable a non-linear loads) were running in system at that time. We saw the filter cap bank was absorbing far more than 25% its rated current. It’s hard to repeat the same scenario if the test conditions were not the same in both cases.
Regarding note 3, something still looks strange to me: “…With 415V input voltage, the maximum DC bus voltage level is approx. 620-630V…”. Normally the Drive with a 6-pulse rectifier and without harmonic filter should be has 560Vdc (x1,35 conversion factor) at input voltage 415Vac. Also depending on power source the Drive DC Bus can drop more 10-30 Volts when the drive runs full rated amps. At their case they tested DC Bus at 620-630V level - 12.5% higher than normal DC Bus. I can see this phenomenon when the drive is not running but when it runs under rated load those results are hard to believe.
Thanks, NNG.

 

[ICEMAN]

NNG....

I agree with your comments re the AC line x 1.35 but as there was a voltage boost with Lineator even at rated load. It may be that the theorical 415V +10/-6% came into play here. The graph clearly shows a drop in volts with Lineator from no load to full load against a similar graph of volts without Lineator suggesting that the mains was high in the first place. I'll revisit that report tomorrow and confirm that.

One of the problems with this report is maybe that it is dated 2000 so it was one of the early Lineators (90kW). They have continually developed since then and as far as I am led to believe there is no voltage boost on no/light load with the Advanced Lineator.

The report goes on to say that there are no problems running with multiple Lineators on one power system when on utility or generator derived supplies.

ICEMAN

 

[jbartos]

Suggestion to ICEMAN (Electrical) May 13, 2004 marked ///\\jbartos..Your link to the site re Duplex Reactors does not work. Can you check it please and ensure it is correct. If not give me more details on who makes it. Thx.
///Please, cut and paste the link into the browser URL or "File" "Open".
It is working. Normally, when you see links that are not blue, this is the last resort to get to the sites.\\\

 

[ICEMAN]

Hi jbartos....

I downloaded that brochure in the link re duplex reactors. Unfortunately, two sentences do not tell you much ! Thanks anyway.

ICEMAN

 

[jbartos]

Comment on the previous posting:
There is a schematic diagram. Often, many electrical engineers can take it from there with ease. Please, notice that this is Eng-Tips Forum. For detail instructions and education, there are various other and official educational institutions.

 

[fluxcap]

Sorry to have joined so late, better late than never I guess.

We were lucky enough to have a Mirus rep come thru the office and do a presentation a few months back... an excerpt of my notes from the presentation.

Lineator:

"Simple line reactor with multiple windings on a common core" (I noted similar to a zig zag with the following differences) and third winding with capacitance.

L1 winding - high impedance (tuned below the 5th to prevent importation of upstream harmonics back towards drive) Wound with polarity marks toward line side of system

L2 winding - output winding (tuned near 7th to remove load side harmonics) wound with polarity towards the drive.

L3 winding - tapped between L1 & L2 with polarity towards L1 on same common core with cap bank connected. Cap bank nearly 6x smaller than MTE units.

The MTE/Danfoss units appeared to have 3 to four separate reactors acting as a low pass filter.

Test data that Mirus quoted by Toshiba included the following:

For a 150HP Motor

@100% Load: Fundamental
Speed: TCHD w/Mirus TCHD w/o
60Hz 5.8% 67.7%
45Hz 6.8% 74.3%
30Hz 8.5% 84.2%
15Hz 10.1% 101.9%

At varying Load:
60 Hz Speed

Load: w/mirus w/o
100% 5.8% 67.7%
75% 6.5% 73.2%
60% 8.7% 86.2%
25% 11.4% 108.7%

Based upon the smaller footprint of the units, the guarantees, the ability to handle the variable loads of our application and the price advantages over higher pulse drives we are planning on installing some of the mirus units later this year.... hopefully can repost positive results at that time.