Harmful effect on power systems from using big VFDs or tons of computers at home
 

An old small industrial VFD or new bare-minimum built CHINA MADE VFD eBay devoid of all but the essential parts can have a power factor of 0.5 to 0.6 with a total harmonic distortion of 100-150%.

The power company provides medium voltage power to a distribution transformer in your subdivision to provide the low voltage power. A subdivision with 10 houses with average power usage level will have something like 34.45kW of demand. This is computed by 7.03kW demand x 10 homes x 0.49 coincidence factor) Such a subdivision maybe fed from a 50kVA transformer. The short circuit rating on this type of transformer is about 4,000A wth a 5.2%Z rating.

When some DIYer installs a surplus industrial/eBay China made 3 hp VFD without harmonics filtration out of ignorance or selfishness, it wreaks havoc on the local power system and cause this to happen to the entire subdivision:

http://i.imgur.com/CfYJonV.jpg

http://www2.schneider-electric.com/m..._solutions.pdf

The losses in the power company transformer also increases substantially which means the power taken from primary side is greater than it is with a 3kW non-harmonic load. The additional loss contributes to increased "carbon footprint" and energy consumption which is anti-eco.

You can expect an input power of 3kW after motor and drive losses at full output. The highest 15 minute average is used for demand in the power industry and since you can anticipate it can operate more than 15 minutes at a time at full load, 3kW will be used for demand.

VFDs and computer power supplies contain power electronics that produce e EXTREME amounts of harmonic currents. The problem is that power system for subdivision of 10 homes is not designed to see 3kW of sustained harmonic load. CFLs do not escalate to this level of problems unless you switch on 230 13W CFLs all at once and leave them on for well over 15 minutes in a subdivision of 10 homes. Yeah, that ain't gonna happen in real life.

A large, straight rectifier power supplies with straight rectifier input is common in internet general purpose CHINA MADE VFDs.

Why is it a problem when someone use power polluting loads that is not even meant to be used at home like a 3hp VFD or run ten computers to do "coin mining" mining and do dumb stuff like "omg I'll save 40W between mah ten computers if I bypass the PFC".

A 0.5PF 3hp VFD will have an input characteristics of
240V
input amps: 25A RMS, 6kVA total
PF 0.5
60Hz components: 12.5A, 3kW
THD of 100% fundamental: 12.5A, 3kVA
3rd harmonic is probably in the order of 2.4kVA
PSC used in air conditioners produce no harmonics and power factor is close to 1.0.

That one customer is drawing 3kVA of harmonic demand on the subdivision transformer at the point of power coupling. 3kVA/34.45kVA =8.7% TOTAL DEMAND DISTORTION (TDD)
IEEE 519-1992 recommendation is not more than 5%.

Computers, ECM, X13 and such from all the other homes will add up to about 2kVA for a combined total of 5kVA or 14.5% TDD leading to situation that breaks the camel's back.

100 CFLs turned on at the same time across 30 houses would not be an issue, because, the demand is small RELATIVE to the total demand and transformer size that would be used to feed 30 houses. The effect of you alone 3kVA of harmonic current depends on the size of the subdivision transformer on which you're connected.

The attached PDF tells you the effect of when proportion of harmonics relative to total demand and transformer size is excessive. This is an example of large portion of electronic battery charger being used at the same time by one customer. High proportion of harmonic producing load reduces efficiency of power company transformers and reduce efficiency of induction motors used by other customers by distorting the voltage waveform. Both of these have negative environmental impact.

This is why harmonic loads often cause a problem with generators. The harmonic producing dirty load is HUGE relative to the capacity of your home generator which is much smaller than the neighborhood distribution transformer. When you have to "oversize" generator to work with harmonic loads, you get a first hand experience of concept of wasted capacity.

Until recently, harmonic loads relative to total demand was negligible in residential power systems. Increased use of CFLs and harmonic producing embedded systems type appliances is changing this.

A 3 hp VFD in an industrial facility or an apartment complex with a 400kW demand fed from a 1,000kVA transformer is not a problem, because it's small in proportion to the local power system.

And your dissertation says what? Inverter-drive mini-splits are evil? Edison was better than Tesla? Time machines are cool? I don't get it.

OEMs recognize the power quality issues in these large harmonic producing loads and consumer oriented products like production spec mini-splits do have harmonic mitigations.

So could I rob power from the grid by leeching off the harmonics and rejecting the fundamental frequency? If I could catch that reflected power, I don't think the power utility would mind. I don't think they would come looking for me.

That's exactly how devices cause problems on the grid.

If you were going to apply brakes on your bicycle you can:

apply smooth and steady braking throughout the rotation.... "clean load"
applying 1 x brake pad force over the entire 75 inch circumference of the rim

or you could apply "dirty load" much harder in very short bursts and only when the wheels are in 12 and 6 o c'lock positions.
10 times the force applied to 3.75 inch section at a time, twice per rotation.

This is how dirty power computers draw power.

Even if you do it so that braking effect per rotation (the same amount of power dissipated per rotation) is the same, the latter is a lot more troublesome.

The brakes are not "producing power" but you can see that there will be vibration that is in multiples of rotation of the wheel. Given the same braking load, the same will have a lot more effect on a bicycle(say subdivision transformer) than on a truck (a 1000kVA transformer feeding a factory).

The modern issue with dirty power drawing inverter drives(VFD) and power electronics is the proliferation of dirty load relative to smooth and steady load. Power factor corrected devices avoid these issues, but China factories and OEM are opposed to it because of cost.

Work out what the power factor of a non PFC rectifier load would be if you gave it a square wave. (Answer: exactly 1)

Granted, that's a theoretical result only as a true square wave (with infinite slew rate) can not exist, nor is it even desirable. So make it a slew rate limited square wave ("trapezoid wave") where the slew rate is chosen to be reasonably fast, but slow enough to avoid EMI. The flat parts are effectively DC, but the transitions allow arcs to quench just like what happens with AC. Think of it as a compromise between DC and AC.

The question now, of course, is where would you find such a waveform? As it turns out, it's actually a very good waveform for a power inverter to output. During the flat parts of the wave, the transistors are simply left on or off as needed, with PWM only used to control the slew rate. That significantly improves the efficiency. It works even better with non PFC rectifier loads. The loads then only draw power on the flat parts of the waveform, requiring the inverter to only supply a small amount of current on the transitions to overcome capacitance.

It's also possible to design a generator to output trapezoidal waves, and in fact, the motor/generators in many hybrid and electric vehicles do just that.

Look into the future where alternative energy is the norm and rectifier loads like PoL (Point of Load) VFDs are everywhere.

No, you don't get what I'm trying to say.

One could build a device that could connect to (someone else's) electric service and "clean up" their dirty power consumption by drawing off power during the times in the AC cycle when there was little or no load. Some of that power could be added back in during times of heavy load to boost the source, making the overall draw seem average. This could possibly fool the electric power meter, maybe even reducing the user's electric bill. The power not added back in could then be siphoned off by me and used at my discretion.

How could this "energy washing" machine be made?

Yes, it has been done. See Technology Review a couple years back (spin the meter backward).

Steve

Get the electric company to install a line drive reactor at the point where they occur.
Several papers are published by the IEEE. Google "vfd harmonics" I couldn't get the correct url posted here without mistakes.

If you'd like your fvd questions answered by power line engeneers, go here:
Eng-Tips Forums

No, you're looking into the near past. As dirty load concerns grow, regulations will tighten and I expect the expansion of something similar to IEC directives in Europe regulating harmonic producing products that can be sold.

With the advent of real-time monitoring and two way communicating " embedded systems " smart meter instrumentation, it can become economical to implement firmware software based DSP digital for demand billing, harmonics or power factor penalty or auto reporting to sniff out and document source of noxious polluters without the costly task of manual investigation.

Please see the attachment to my first post. Now solution can be as easy as communicating with the customer to work out a plan.

Consider a customer engaged in unreasonable use of service such as running a roomful of bit-coin mining machines with omg so 1337 h4x PFC bypassed power supply or a multi horsepower unfiltered, minimally filtered VFD that was not meant to be used on a residential service and producing disproportionate amounts harmonics.

When power quality issues arise and that customer is unwilling to pay for his proportion of corrective equipment nor is willing to discontinuing the unreasonable use of service, the data gathered can be useful.

The history of making unreasonable levels of power line pollution could be useful in enforcing the terms of tariff "Usage of Service Detrimental to Other Customers" and seek service disconnect or seek judgment for the cost of corrective measures through the legal system.

http://www05.abb.com/global/scot/sco...82003d0201.pdf

Something like that is used to reduce harmonic current flow from getting past the point of common coupling. If the PoCo installs it, its coming out of rate payers. It would be the solution when harmonics at the transformer gets that bad through increased use of rectifier loads, but the idea of something like IEC directive is to prevent that from getting to critical mass in the first place.

See the attachment in this post for an example of harmonics created by one customer affecting another customer. Since the customer was not engaged in unreasonable use and the usage is not avoidable, the power company installed a separate transformer to isolate the harmed customer.

If the cause was from unreasonable use of service like the example I mentioned earlier, it would make sense to bill the offender for the cost of putting the harmed customer on another transformer.

I don't know why this thread is in the Geothermal & Heat Pump area of the Forum. It has nothing to do with any of these things, or with any of the innovative and worthwhile projects and efforts that are here.

It is not project oriented, and is really just an editorial or opinion piece.

I think that this opinion thread should be re-located to the Billiards Room where it belongs.

-AC

I disagree. There are YouTube videos about using surplus industrial VFD at home and discussions advocating it. I think the creator of video has good intentions, yet unaware of harmful effects when more people start doing it.

The air conditioner compressor is the largest motor that gets any significant number of hours at homes. Discussions pertaining to VFD that maybe used for this purpose is a pertinent topic. Things that are harmless when kept to a drop in a bucket don't stay that way when it becomes more concentrated.

Increased losses in the distribution system is wasted energy.

Products that induce power quality problems and require intervention by energy provider are social expenses. Straight through VFD has the lowest manufacturing cost and a fairly high device level efficiency. When some jerk hooks up a industrial 2.4kW 5kVA VFD at home on a 30kVA residential service, the demand distortion is significant. It's no biggie when you're only using them in a small quantity in an industrial setting so that the demand by VFD only adds up to a drop in a bucket. That is how it was two decades ago. Modern residential use inverter ACs do have a fairly effective harmonic mitigation. Cheap China made VFDs sold in the internets will also be the most harmful type that omits harmonic mitigation that adds to manufacturing cost.

The "green industry" is composed of significant amounts of marketing companies that thrive on getting in touch with the consumer's warm and fuzzy feeling about saving the environment using crafty numbers or emotional stimulation. Environmentally unsound projects or solutions disguised as "saving the mother earth" for financial gains and the less visible and delayed harmful effects in the bigger picture negate the benefits, the overall effect can be an environmental and social HARM.

It maybe very well intended but unaware of harmful effects or it could be sham looking for whatever reasons to create demand for products or indifferent to indirect effects or hiding them for the sake of profit. Ruthless bottom line driven green marketing that preys upon the uninformed public is dime a dozen. It's not exactly news flash that businesses hide harmful effects for the sake of protecting profit even if its a total showstopper to the benefits touted. Earlier LED light bulbs and patented, proprietary parts driven embedded systems based appliances with a fairly short factory warranty that wipes out any saving by ONE service call are some examples.

The thing that sets EcoRenovator apart from the majority of opinion-drivel of the web, is that people who are actually doing things, actually building and doing, are sharing their experiences and offering support and knowledge that comes from doing things.

It is the density of that valuable information, and the organization that gives EcoRenovator it's value.

This opinion drivel is a waste of space and valuable time that people could well spend by actually doing something.

This thread should be consigned to the Billiard Room where it belongs.

ICanHas, it is not lost to me that on the occasions that I have asked you to share information and photos about your projects, you have said nothing.

That says it all.

-AC

You misunderstood the type of inverter. Of course you can make run whatever at whatever waveform in an isolated circuit that isn't interconnected. Aircraft equipment operates at 400 Hz for example. You can't just change the grid waveform or frequency to whatever you want whenever you want. If you want something different.

Oh sure. They'll continue to be around. But the movement in the near future is disallowing importation and sales of those harmful equipment without good front-end filtration in North America following the IEC directive model.
http://grouper.ieee.org/groups/harmo...cs/P1495D2.doc

That's your opinion.
Feel free to not read/post if this thread isn't hands-on enough for you.

My 2 cents worth:

EU has had harmonic requirements for over 20 years.

USA does not.

Why _ most heavy power users and high efficiency systems already have PFC circuits as part of the rectification circuitry (e.g UC3854 chip, $2); heck, even the Klimaire 1.5T inverter driven mini-split I bought 2 years ago from China has a PFC front end. Why: the typical PFC circuit boosts 120 Vac to a stable 200V vs drifting 170
vdc, or 240 Vac to 400 Vdc, which makes the inverter design simpler and more efficient, while at the same time raising PF to 95% to 99%.

I suspect that ICanHas is in the business sector that sells power factor correction circuits or else got burnt by ignoring harmonics in one of his designs?

Modern wild frequency aircraft power systems have very high harmonics - there is a BIG weight penalty for aircraft to correct all harmonics. Many vendors/suppliers overlooked the line harmonics in the specs when they built their power supplies, and the supplies went belly up in initial testing giving the incompetent designer a black eye. Perhaps icanhas is one of the design engineers who did not read the power system specs so now caterwhalls about wanting a clean power system.

Biggest impact for POCO is triplett harmonics, as those turn to heat in delta-wye distribution transformers. A high power VFD (most of which have PFC circuits anyway) usually have their own phase shift transformers - say with a straight 24 pulse rectifier, there are primarily 23rd and 25th harmonics, not divisible by 3.

Not to say there are not horror stories about harmonics, but overall economics for the user pretty much dictates PFC circuits anyway.

The EU harmonic requirements are a result of Europe having mostly government run power systems - easier for them to legislate on harmonics vs letting the free market fix the problem itself.

Example - cheap Chinese 6W LED bulbs with no PFC*, replacing 60 W incandescent. Power reduced by a factor of 10, good trade against a few mV of harmonics. If that $4 LED bulb had to add even 50 cents due to PFC circuit, the 54W generating saving would not be taken advantage of by a larger population segment.

* I have a cheap open CFL in hand, and am looking at the circuit - easy to do, one sided circuit board and no ICs. 4 diodes, small inductor, 10uF 200
v cap, 2 4124L (fets?) drivers to small transformer - saves over 50W for same 500 lumens, adds about 10 mA or less harmonics to input current waveform.

As far as DIY folks 'polluting' the grid, what a crock - there are so few DIY that use multi HP non PFC VFD that it is a teaspoon in the ocean.

In one video where someone installed a VFD on a central A/C, the amperage draw went down, not just the wattage. Granted that was under a specific set of conditions (no doubt including an A/C that was oversized to begin with), but that means the overall VA draw also went down.

Maybe what we need is an open source VFD targeting residential HVAC applications, able to drive 120V or 240V split phase motors (depending on components used) and 208V 3 phase motors. It can be designed with both the hardware and software open source, including high efficiency digital PFC. It could even be possible for the software to automatically tune the PFC (output voltage and cut in point) for peak efficiency at a given load condition, while maintaining a user set minimum PF or maximum amperage limit. Some advanced DIYers out there have built their own EV motor drives and chargers. A HVAC motor drive should be quite a bit simpler in comparison.

Well, not yet at least. Did you get to take a look at the IEEE doc?

"A typical transformer rating for residential application is 25 kVA or 50 kVA with services run to between 6 and 10 homes.
"

"The U.S. distribution system is more susceptible to problems brought about by the third harmonic. Third harmonics readily pass through the wye wye connected transformers in the U.S. "

Remember that it is a mini-split specifically designed for use on residential service and global market meaning that it has to meet the regulations of target market. You'll find that many big screen TVs have a 100-240v power supply with a PFC so that the same power supply can be used regardless of destination market including where it must meet IEC directives.

IEEE report describes US residential distribution systems commonly use 7200 - 120/240 single phase transformers hooked up line to neutral.

Given the wye-wye nature, the harmonics from ever increasing non-linear loads add up in the medium voltage line 12470Y/7200 side. The harmonic current level at the substation level is much higher now than it was designed for in the era when harmonic demand from electronic loads were only present in much smaller amounts.

It will take 500 of those fired up simultaneously off of the same distribution transformer to equal the effect of one non-residential VFD with a 3kW input.

So, under any ordinary applications, their effect on total demand distortion applied on the distribution transformer is low. Even the IEC only applies harmonic rules to power supplies with input power over 75W. I believe they're dropping that down to 50W in the near future.

In the US, though not a direct legal mandate, "Energy Star" qualification is essential in marketing and many utility sponsored rebates require it. A straight rectifier bulk capacitor link LED product that is over five watts do not qualify for Energy Star, because power factor must be over 0.7 and this is not possible with the level of harmonics produced by the bridge/capacitor input. ( http://www.energystar.gov/ia/partner...quirements.pdf )

This obviously depends on each location. The level of voltage harmonic distortion that will be produced at the point of common coupling is much more severe at a rural location.

In a rural area with a 15kVA transformer serving two homes:
3kVA of harmonic current on a 15kVA transformer serving two homes that sees an average demand of 10kVA is has a total demand distortion of 30%. At the local level, this is an ounce in a cup.

The same VFD used on a service in the city where it's fed from a 208Y/120 feeder with a 1,000kVA+ of transformer capacity, it would be a few drops in a bucket.

This can occur if one of the house is using an A/C unit modded with an industrial 3 phase 6-pulse VFD running on a single phase service, or using a bunch of computers doing "coin mining" or running a ton of electronic ballasts to grow weed. This can be fixed by putting the neighbor on a separate transformer, which is very expensive. The added standing loss from having two transformers as well as the reduction in conversion efficiency of the one serving the offending load, the effect of "power savings at load" by "skipping harmonic mitigation" is now overwhelmed.

It would be a "drop in the bucket" by the time it gets to medium voltage substation, but the impact is not at the local level. Since this will throw the voltage distortion beyond whats permissible at the PCC that is supplied to the neighbor,it can be considered "Usage of Service Detrimental to Other Customers" by tariff agreement as authorized by the PUC.

Then there's a further cost involved in the process of forcing the offending customer to pay the expense of putting his neighbor on a separate transformer or getting a court order to disconnect the harmonic load or install filtration device.

Not all VFDs are the same. What is true to a harmonic reduced VFD do not translate to the same holding true for the stripped down bare minimum VFD one buys from Alibaba.

A 500W 1kVA load from a very lightly loaded induction motor do not produce the same level of losses in the transformer as diodes and capacitors used in computers.

Maybe we need more implementations of electromechanical pneumatic modulated technology such as the Copeland Digital modulating devoid of all this power electronics crap.

I'm thinking I would use one of these on my heat pump.

Think it might bring down the grid? They're pretty cheap.

I disagree. EU Regulations drive ever closer technical specifications in order to promote a cross-border electricity market, whilst at the same time forcing government run power systems to be privatised. I don't think there are any government run power systems left in the EU, but there are technical regulations despite that, so I don't see that these two issues are inter-dependant.
This is just the same as any other market. For example, there are EU regulations about car specifications, covering everything from emissions to lighting to safety etc, yet there are no government run car factories. You don't need things to be government run for them to be government regulated.

There's no easy answer. It depends on the kVA size of transformer feeding your house, your load size relative to that rating and percentage of your load relative to total load at the time.

The billable charge is the bus fare you pay.

If you alone bring extra luggage and use three seats when there are plenty of empty seats, the effect is negligible.

If many people did this and reduced the number of revenue producing seats during busy time, they have to add buses to carry the displaced people, thus each of you is collectively contributing to wasted energy by wasting capacity. Answer? not "eco friendly".

Harmonics are even worse. They're like those people who bring loud arse kids who cause QUALITY of service issues to other customers.

Sheer stupidity like removing existing harmonics filter/PFC and advocating it online is like littering, bragging about it and telling kids littering is good and they should litter more. Advocating something that do not have it to begin with is more like encouraging the purchase of more polluting products.

thanks for agreeing 95% <G>

as for :
cost involved in the process of forcing the offending customer to pay the expense of putting his neighbor on a separate transformer or getting a court order to disconnect the harmonic load or install filtration device.

Would be very interested if you can provide even a SINGLE case law reference to this ever happening at a residential DIY level....

The first industrial case law IIRC is that Colorado Springs disconnected a certain Mr. N. Tesla from their grid when he shut down the system with an inordinate overload - maybe one could call N. Tesla a DIY, sure we would all be complimented.

That particular VFD did not have PFC. In fact, it was a 480V VFD being run off a voltage doubler since he managed to get a 480V condensing unit (and the VFD to run it) for super cheap.

All you've got is anecdotal evidence. The measured current could very well be incorrect if it was not measured correctly using a right instrument.

Please provide the kVA, kW, THD and 3rd, 5th, 7th, 9th and 11th harmonic percentages.
It's not the high VA to kW ratio per se that's the problem. It's the harmonic content, especially the 3rd harmonic that affects power quality to other customers as well as disproportionately higher losses in transformers.

Did you advocate the dirty power drawing diode-capacitor front-end and convince him to do ti?

Thank you ~




One install would not affect it at feeder level. It would affect it at the nearest PCC or causing enough localized pollution to affect delivered power quality to neighbors. What's your ground for calling it "what a crock"? 3kW 6kVA >100% THD is easily over 10% of demand on subdivision transformer.

From the IEEE draft:

"Employing electronically-commutated motors (ECMs), the input of a variable speed heat pump resembles a large switch-mode power supply (e.g., 3 kW or more). The ECM is a dc brushless motor with stator construction similar to a three-phase ac induction motor. The stator winding current is sequenced and switched creating a rotating magnetic field. This switching is performed electronically by an inverter. The rotor uses permanent magnet construction.
Conventional heat pumps have a current THD of 13% with around 9% third harmonic content; some of the newer ECM designs have current THD values of 123% with the third harmonic content of 85%.
Because of the large load, there is concern that it would only take relatively few installations of this type of heat pump to cause voltage distortion problems. In [2], the authors found the voltage distortion on a distribution feeder reached 10% when the penetration rate for these variable-speed drives reached 10%, i.e., when 10% of the homes installed the new ECM designs. Though a 10% THDV would be deemed unacceptable by most of us, it does give us a sense of how much of a particular nonlinear load would cause problems on a residential feeder.

[2] International Standard IEC 1000-4-7, “Electromagnetic Compatibility (EMC), Part 4: Testing and Measurement Techniques”.

No, he did it well before I found the video.
R134a heat pump in heating mode (short) - YouTube
He's actually very knowledgeable about HVAC and power electronics.
subcooledheatpump - YouTube

But you didn't answer my question regarding THDi values on that system. This thread is about power system pollution. You literally posted YouTube videos from those people all over the place. I'd rather you didn't use my threads for ad space for that stuff especially since that don't address anything that is being discussed about here.

Here's food for thought.
Some people think HVAC systems should use dangerous refrigerant and drive technology that is devoid of power pollution prevention technology or use photoelectric conversion energy source laden with serious amounts of toxic cadmium with power electronics parts manufactured with all sorts of dangerous chemicals that presents the same type of issues as lead paint and asbestos at the end of life, then hate on people who drive Hummers and Excursion, because that's the trendy thing to do among millennial.

It's hard to tell if that's any better or worse than using thermostat with lots of mercury, mercury flame sensor, PCB capacitor PSC motor, R22 refrigerant and drive a 1965 V8 muscle car with chlorofluorocarbon 12 filled AC.

Cadmium telluride photovoltaics - Wikipedia, the free encyclopedia
If that still bothers you, stick to the silicon based panels.

Also note that a lot of cordless power tools are still using NiCd batteries. Lithium works better and is less bad for the environment, but is flammable, requiring proper mitigation of the hazard. Really no different than advocating the use of hydrocarbon refrigerants to replace fluorocarbons. (And that unit in the video does not use hydrocarbons, just R134a.)

I strongly advocate repairing electronic stuff that is worth repairing and selling/donating the rest (uneconomical to repair or otherwise no longer useful to you) to the educational/DIY market. In particular, students can learn a lot repurposing old electronic stuff.

Ok., so when do you think the general public will catch the wave and start building their own homebrew air conditioning system s with dirty vfd driven power supplies? And when will they go back to good old core and coil setups? My guess on both counts is never.

You said yourself that the majority of manufactured devices have built in power factor correction.

So what does this really have to do with anything not completely wingnut in nature? Sounds like a lengthy armchair discussion to me.

What I want to hear more about is a harmonic eating power cleaning device. Something that I can rig up to keep all that dirt the power utilities don't want back anyway.

As I said, even one unit can have adverse effect depending on distribution transformer size.
It is about "eco friendly" so if the energy consumption that is inclusive of transformer loss and reduced reduction in your neighbors' AC motor efficiency overwhelms your point of use energy savings, you failed at reducing energy use.

When PoCo starts assessing penalty for harmonics which becomes easier than its ever been as smart meter enjoys greater penetration.

We're already getting our feet wet with this upcoming problems which is why the future is in mandatory integration of such cleaning parts into every harmonic producing equipment much the same way as catalytic converter mandate on cars.

I already linked you to it. The ABB link. Some inverter mini-split A/C units already have a very effective harmonic mitigation built into it. The ABB version and the one built into some modern electronics is the active PFC type.

Here's a passive type:
http://www.artechepq.com/assets/files/SinglePhase.pdf

That type of passive filter was very common for somewhat older IEC spec computer power supplies as well as US spec electronic ballasts. That sort of external mitigation is not needed if it is already taken care of within the device.

ANSI requires THD of <32% for lighting ballasts. This was a requirement created in response to earlier unfiltered ballasts causing problems from excess harmonics. The old design was well before electronic ballast load became a big proportion of commercial building load.

The increased use of non-linear load is headed the same way as they gain share in percentage of load supplied to homes.

And then someone finds a practical solution to the arcing issue with HVDC (380V or so), making PoL PFC obsolete. HVDC just makes a lot more sense when most (residential scale) alternative energy sources are DC, as are most electronic devices. Large motors are served by PoL inverters, giving them the benefit of variable speed and efficiency optimization at the same time.

Oh hi, welcome to 1920s.
http://cityroom.blogs.nytimes.com/20...thomas-edison/

The point was DC power distribution in a building or at most a small cluster of buildings, not long distance. 380V DC is becoming increasingly common in data centers and many off grid houses have DC power distribution, typically 12V, 24V, or 48V depending on the types of loads and length of wiring. Telecom has been using 48V power distribution for decades.

When your main power source is DC, as in solar panels and batteries, what's the point converting it to AC just to run electronics that really run on DC?

HVDC? You're off 3 decimal places. We do have HVDC, the pacific intertie at 1MV (aka 1,000kV )

Only SOME ' alternative ' sources are DC.
Look at Voith WinDrive based wind generation, an innovative German design that does not use the reliability reducing power electronics converter.

All that has nothing to do with this topic. This thread is about the impact of proliferation of harmful loads that are being added to the public power system, not about your proposed private distribution system within your premises.

Look up "HVDC data center". In that context, 380V is a common system voltage. It's very unlike the hundreds of kV HVDC transmission lines.

If the AC to DC conversion is done in one place, that would be where to put any required PFC stuff. There are also "wild frequency" AC sources like windmills, which are usually converted to DC for use.

Again, we as individuals cannot control what kind of equipment the power company supplies us power with. We just pay for it and let someone like you deal with how to supply it. If the power company has a problem with my homebrew experiment and the cheap chinese cfl lamps they gave me for free, I'm sure I'll get aletter in the mail or sumthin.

You're right we don't have a choice as an individual in power transmission equipment.

We have the choice to use or not use polluting technology. Awareness helps you realize something you maybe overlooking.

It isn't ILLEGAL for someone to drive a pre-cat 7mpg V8 400 cid Impala every day in Los Angeles or use an AC unit that creates 175% harmonics with a 3kW draw assuming that the said retrofit/modification was done with the necessary permit and passed permit.

Things like cat delete or PFC bypass can make certain numbers look favorable, but goes against the original intent or have other harmful effect. If the intent is to reduce contributory harm, but you're actually increasing it, it's just so sad, isn't it?

We can't choose what they use at the sewage treatment plant, but we have the choice to opt for products with lower contributory harm. Same with appliances.

As far as supply sided control light bulb efficiency, catalytic converter requirements and permissible refrigerants are some examples of legislative measures.

Many incentives offered by utility sponsored programs require standards above and beyond the legal mandate. These definitely affect purchase decision. So, it wouldn't be illegal for utilities to add harmonic content or standby power into qualification criteria so that devices with higher levels of harmonics don't qualify for incentives, or heck strip subsidies for "photovoltaic" and reallocate the funds in efficiency improvement project such as subsidizing rewards for homes with low harmonic content. Look at those moaning and groaning about it as public monies incentive are thinned down on photovoltaic installs or discontinuation of lucrative net metering buyback rates.

Ummmm, excuse me but the inverters needed for solar PV have total THD of less than 4% so it don't think they are a major contributor here. They actually help to clean up the grid.

Stop blaming solar. It is the way of the future and all we need is to have better grid integration methods. They are coming but be prepared for a major utility backlash (which is mostly BS).

I wasn't blaming them for that. They're not "load". I am referring to electronic loads, like variable speed motor drives which is often called "inverter drive". You're thinking of the wrong inverter, the one that ups power into the grid.

But we're not talking about it in specific end-user industry. Data centre would be so called medium voltage customer with customer owned distribution equipment.

Purpose specific centralized DC electrification is nothing new or novel. It's been around and been done since the second industrial revolution for electrolytic processes and railway traction power.

Edison system was in use and remained in use until fairly recently in Manhattan, but Westinghouse system dominated. Now, looking to take a step back, we must make the decision. While they pulled the plug on DC, they're still in use and newly deployed all the time for light rail systems all over the world.

But the real question is... how do we make direct current electrification power from 3phase alternating current electrification?
this?
http://i.imgur.com/m6hbXHC.jpg
or the modern motor-generator back to back power conversion technology known as the MG set?

There's also a commutatable static rectification and inversion technology known as the mercury arc valve

http://i.imgur.com/LjEQIc5.jpg

AC to DC is the easy part - just a bunch of diodes and capacitors can do the trick. The reverse is quite a bit more complex.

In the case of a data center or other large, mostly DC loads, PFC rectification (for the entire site) can be done with a bunch of 3 phase transformers and rectifiers wired in such a way that few harmonics are generated in the first place. Especially with the trend towards eliminating A/C in data centers, that only leaves a bunch of big fans as major AC loads, which are likely to be VFD driven anyways. Alternative energy such as solar panels can feed directly to the HVDC bus through a MPPT controller. The backup batteries can be more or less directly tied into the bus with some isolation circuits to allow them to be automatically tested.

Presumably, they could use the same bunch of 3 phase transformers and rectifiers to serve entire neighborhoods, particularly those that are predominantly DC loads.