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

[ICanHas]

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/

[NiHaoMike]

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?

[ICanHas]

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.

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.

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?

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.

[NiHaoMike]

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.

[jeff5may]

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.

[ICanHas]

Originally Posted by jeff5may

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.

[Mikesolar]

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).

[ICanHas]

Originally Posted by Mikesolar

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)

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.

[ICanHas]

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.

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?

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

[NiHaoMike]

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.