EcoRenovator  

Go Back   EcoRenovator > Improvements > Geothermal & Heat Pumps
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 08-30-14, 11:39 PM   #41
ICanHas
Banned
 
Join Date: Aug 2014
Location: US
Posts: 150
Thanks: 7
Thanked 5 Times in 5 Posts
Default

Proprietary distribution is unpractical without a large consumer of this service.

Nuthin' innovative about private DC network. 600-750V LVDC is used all over the place for internal consumption for traction power at railway substation using a private grid.

Data centres are not an ordinary user. They've a very high demand density and have a fairly sustained demand, so the capacity of power conversion infrastructure is utilized effectively.

Developers are free to use their own and investor funds to develop such thing within their campus and purchase medium voltage service through the PoCo and build their own valve hall on their property to house mercury arc valves .


Last edited by ICanHas; 08-30-14 at 11:41 PM..
ICanHas is offline   Reply With Quote
Old 08-31-14, 07:05 AM   #42
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,428
Thanks: 431
Thanked 619 Times in 517 Posts
Send a message via Yahoo to jeff5may
Default

Mercury arc valve rectifiers? Really? Those devices are so 1922.

Arc discharge tubes are an eco-nightmare. They contain large amounts of mercury by design, and they all leak. They are very finicky and fragile. While in operation, they emit a wide band of radiation, from rf all the way to ultraviolet. One cannot be near them in operation without protective gear for fear of being cooked or sunburned, much like being near a welding arc. To try to mitigate these risks, the high power designs use a steel tank enclosure. This also prevented them from melting down under maximum load. Not a popular device, too many risks, even then.

However, they do work with whatever "dirty" AC power source you throw at them. Mercury doesn't care how hard it's being fried, it vaporizes the same either way.

Fast forward to today. The electric and electronic sectors are doing their best to eliminate toxic heavy metals from their end products and processes. Mercury and lead are at the top of the list to be eliminated from everything at all cost. Metal halide and fluorescent tubes are being replaced by high power LED arrays everywhere. Much like the R410a situation, cold cathode and cfl bulbs replaced the "evil" tungsten incandescent bulbs with another design containing "less" heavy metal as a short-term solution. Now, the high-density diode emitter has come of age, and is replacing the fluorescent bulbs and arc-discharge tubes for nearly every lighting application known to exist.

These ancient technologies you sell went away for good reasons. The arc discharge rectifiers themselves were not overly inefficient while operating, but they were designed for fairly constant loads. Too little or too much load, and they either die violently or cannot sustain operation, needing a jump start for the arc. The inductors attached to these tubes to smooth the waveforms generated were somewhat lossy to say the least. The equipment reminds me of a Frankenstein movie or anything Nikola Tesla in nature. Not an easy sell to the public or a pool of silent investors by any stretch of the imagination.

Last edited by jeff5may; 08-31-14 at 07:30 AM.. Reason: perspective
jeff5may is offline   Reply With Quote
Old 08-31-14, 08:36 AM   #43
ICanHas
Banned
 
Join Date: Aug 2014
Location: US
Posts: 150
Thanks: 7
Thanked 5 Times in 5 Posts
Default

Quote:
Presumably, they could use the same bunch of 3 phase transformers and rectifiers to serve entire neighborhoods, particularly those that are predominantly DC loads.
Neighborhoods frequently don't even have 3 phase power or transformers coming to them. Many of those transformers are SINGLE PHASE 7,200 V medium voltage to 120/240 LOW voltage.

Well, you and your investors can gather the funds, then negotiate property easements for power conversion equipment or purchase/lease the land yourself and operate your own micro utility.

Last edited by ICanHas; 08-31-14 at 08:38 AM..
ICanHas is offline   Reply With Quote
Old 08-31-14, 11:04 AM   #44
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,428
Thanks: 431
Thanked 619 Times in 517 Posts
Send a message via Yahoo to jeff5may
Default

Quote:
Originally Posted by ICanHas View Post
Neighborhoods frequently don't even have 3 phase power or transformers coming to them. Many of those transformers are SINGLE PHASE 7,200 V medium voltage to 120/240 LOW voltage.

Well, you and your investors can gather the funds, then negotiate property easements for power conversion equipment or purchase/lease the land yourself and operate your own micro utility.
OR NOT.

Now that you mention it, most (if not all) industrial power consumers do exactly this. They usually don't even deal directly with the local power company, except for delivery charges, after the substation design and install. They buy grid power on the commodity exchange from a broker who hunts for the cheapest source of the day. No rules to speak of besides who pays who for what and when. Not like residential service at all.

This is how I believe off-grid systems or grid-tied systems should be regulated (very little). If the local power companies could agree with each other in any sense of the matter, this might be possible. However, they all tend to take their own stand on special circumstances and situations (such as net metering and power cleanliness and time of use rates and...), so a joint agreement of any type will never happen. Everyone along the supply chain has to make money, and all this expense is handed down the line TO ME.

As small consumers, we are force fed a gob of media and hype to justify these strange charges on our bills. These charges change every six months or so, depending on both Congress' mood in twisting federal law, and the local power companies' desires to increase shareholder value. Both entities tout major upgrades and drastic efficiency boosts, with no cost reduction whatsoever on my end.

Last edited by jeff5may; 08-31-14 at 11:10 AM..
jeff5may is offline   Reply With Quote
Old 08-31-14, 05:49 PM   #45
ICanHas
Banned
 
Join Date: Aug 2014
Location: US
Posts: 150
Thanks: 7
Thanked 5 Times in 5 Posts
Default

Quote:
Originally Posted by jeff5may View Post
OR NOT.

Now that you mention it, most (if not all) industrial power consumers do exactly this. They usually don't even deal directly with the local power company, except for delivery charges, after the substation design and install. They buy grid power on the commodity exchange from a broker who hunts for the cheapest source of the day. No rules to speak of besides who pays who for what and when. Not like residential service at all.

This is how I believe off-grid systems or grid-tied systems should be regulated (very little). If the local power companies could agree with each other in any sense of the matter, this might be possible. However, they all tend to take their own stand on special circumstances and situations (such as net metering and power cleanliness and time of use rates and...), so a joint agreement of any type will never happen. Everyone along the supply chain has to make money, and all this expense is handed down the line TO ME.

As small consumers, we are force fed a gob of media and hype to justify these strange charges on our bills. These charges change every six months or so, depending on both Congress' mood in twisting federal law, and the local power companies' desires to increase shareholder value. Both entities tout major upgrades and drastic efficiency boosts, with no cost reduction whatsoever on my end.

It would be much more cheaper and preferable for energy providers(and other rate payers) to make these changes. Rural customers are especially a HUGE burden. They'd much rather make it be like a driveway shared by two houses. If it runs through other people's property, well, then you're on your own to figure out easement on your own. Right now, every rate payer subsidizes the cost of delivery on these very high cost vs revenue service. If they make changes so that everything within red outer box is the responsibility of the customer, you're subsidizing these high cost users less.

If a tree messes up the private medium voltage overhead line, the PoCo could locate a service provider or sell you the service, but oh well, the cost of repair is on YOU. Outage at 10PM on Sunday because of private medium voltage line problem? You can wait until Monday or the after hour service is on you.



"net metering" works like flying your private jet along the same route as a commercial flight, then offering the extra seats in your plane to their passengers who would not be able to fly otherwise, because their plane is full.

If they're paying you to carry their passengers to the capacity of YOUR aircraft even if there are space on their own plane, it makes no business sense.

If they're letting you fly on their empty seats on low-load flights, the difference in what they charged their full fare paying overbooked customer and what they paid you to fly them must exceed the lost revenue in what you would pay to fly in their off-peak seats.

The current Net Metering is HEAVILY regulated. The way it works makes it such that lost revenue from your off-peak flight that you would utilize no matter what exceeds the cost you save them. The regulation forces them to pay you the full retail fare to fly in your plane that flies along side them even if their seats aren't really full.

If it was up to the private industry, they'd want to run full flight every flight, not 25% full flight during the off time and 110% booked during busy times. Although, if they can overbook at full fare then utilize your excess seats, then split the profit, it is win-win.

On the other hand, if your 25 seat private jet only has 5 seats and the commercial's first class is deserted, the cost saving from having them go fly on their seat is great.. compared to the cost of flight.

You must look at it from business perspective. The idea of net metering works, but the allocation scheme is so lop sided that it is financially unsustainable.

Last edited by ICanHas; 08-31-14 at 06:33 PM..
ICanHas is offline   Reply With Quote
Old 08-31-14, 06:09 PM   #46
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,428
Thanks: 431
Thanked 619 Times in 517 Posts
Send a message via Yahoo to jeff5may
Default

I am now convinced you came here in a time machine from sometime before World War II.

Just join the doomsday preppers, the world cannot survive the way it is. Prepare for the zombie attacks to come and such.
jeff5may is offline   Reply With Quote
Old 08-31-14, 07:10 PM   #47
NiHaoMike
Supreme EcoRenovator
 
NiHaoMike's Avatar
 
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,154
Thanks: 14
Thanked 257 Times in 241 Posts
Default

Something unique about 120/240V "split phase" (really center tap) is that with only two diodes, it can be turned into 170V peak DC (with a normal PFC stage afterwards if needed) and end up with half the diode losses of bridge rectifying 120V. Unfortunately, most applications with enough power use to truly benefit from this need more than 170V in the first place and would do better just bridge rectifying 240V. It also won't work properly if connected to 120/208V.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...
NiHaoMike is offline   Reply With Quote
Old 08-31-14, 08:10 PM   #48
ICanHas
Banned
 
Join Date: Aug 2014
Location: US
Posts: 150
Thanks: 7
Thanked 5 Times in 5 Posts
Default

Quote:
Originally Posted by jeff5may View Post
I am now convinced you came here in a time machine from sometime before World War II.

Just join the doomsday preppers, the world cannot survive the way it is. Prepare for the zombie attacks to come and such.
What makes you think that in 2014, the cost of providing service per revenue dollar isn't higher in rural than high density commercial? If it was privatized, the monthly charge would be substantially more or they would not have bothered electrifying rural areas. So, with modernization and reduction in cost of instrumentation, you meter the power on 7200v that goes out into the middle of nowhere where it serves only a few customers. Let those few customers figure out among themselves how to split the cost of the line and 7200-120/240 transformer that only benefits them.

It's like rural postal delivery. The cost of service is forced upon everyone else by the power of law prohibiting rural delivery fee recovery and forcing everyone else to subsidize them. Less regulations... that's what you're wanting. If they want to build their own generation station and go off grid, it's saving everyone money.

Quote:
Something unique about 120/240V "split phase" (really center tap) is that with only two diodes, it can be turned into 170V peak DC (with a normal PFC stage afterwards if needed) and end up with half the diode losses of bridge rectifying 120V. Unfortunately, most applications with enough power use to truly benefit from this need more than 170V in the first place and would do better just bridge rectifying 240V. It also won't work properly if connected to 120/208V.
They've been doing just this in AC adapters for decades using internal split-phase transformer. Things that work for 10VA don't scale up to 100kVA.

You're going to need 3 wires leading up to the rectifier and since each half of the transformer takes the FULL load each half cycle, so the overall loss is increased. If you're talking about 9v 4.5W DC power source, its not really a big deal if its 50% or 65% efficient and you're paying at the primary side power use anyways.

You're just pushing over the loss to transformer by increasing the loss at the same delivered power, in addition to reducing deliverable kW per kVA of capacity. With the advent of smart meter, the future is integrating power quality analyzer into it to properly assess individual customers penalty that creates harmonics and otherwise do things that reduce utilization efficiency of power system capacity so that they're slammed with the entire cost rather than having it allocated to everyone else.

Good news is that with primary side billing and your own distribution transformer, anything you do to cause the transformer to become less efficient, standby losses, etc shows right up on YOUR bill. It's only about the harmonics, power factor, demand and energy use as seen on primary side at that point.

Last edited by ICanHas; 08-31-14 at 08:16 PM..
ICanHas is offline   Reply With Quote
Old 08-31-14, 09:49 PM   #49
NiHaoMike
Supreme EcoRenovator
 
NiHaoMike's Avatar
 
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,154
Thanks: 14
Thanked 257 Times in 241 Posts
Default

Those three wires are already brought into most homes. I do agree that the application potential is limited as it has to be a device that needs a 240V circuit but internally does better with about 170V DC. Some apartments use 120/208V (with two phases accessible to a unit) and that will cause compatibility issues. One possible application is a variable speed condensing unit with a relay to select between bridge rectifier and full wave mode, boosting efficiency at low speeds. If it detects that it's actually connected to 120/208, it will just stay in bridge rectifier mode.

The harmonics cancel out inside the transformer, assuming there's a PFC stage.

The idea of using "HVDC" for residential power distribution is really about new construction, not retrofitting. It is mostly of interest in off grid homes, not so much on grid.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...
NiHaoMike is offline   Reply With Quote
Old 08-31-14, 10:37 PM   #50
ICanHas
Banned
 
Join Date: Aug 2014
Location: US
Posts: 150
Thanks: 7
Thanked 5 Times in 5 Posts
Default

Quote:
Those three wires are already brought into most homes. I do agree that the application potential is limited as it has to be a device that needs a 240V circuit but internally does better with about 170V DC. Some apartments use 120/208V (with two phases accessible to a unit) and that will cause compatibility issues. One possible application is a variable speed condensing unit with a relay to select between bridge rectifier and full wave mode, boosting efficiency at low speeds. If it detects that it's actually connected to 120/208, it will just stay in bridge rectifier mode.

The harmonics cancel out inside the transformer, assuming there's a PFC stage.
Who's transformer are you talking about anyways?

If there's an effective load side harmonic mitigation like used in lighting ballasts, you don't have much reaching the transformer. Harmonics DO NOT cancel out in single phase transformer and they go right into the feeder as well as cause voltage distortion for customers on same transformer. For consumer products, I think the only effective way is the way they do it in Europe and regulate it on supply end, hold manufacturers responsible.


You're still not getting it. Assume resistive load and ideal diodes. You're still increasing the losses and wasting transformer capacity, because half the transformer carries the entire half cycle at full load.

Given a real world transformer and perfect diodes (zero drop voltage) with 240v primary to 240:120 split secondary and 1kW load, the power entering the primary side is higher at the primary side two diode split phase setup than a bridge diode, because the resistive losses is I^2R, which means doubling the RMS current quadruples the loss.

Make everything real life. If the diode loss offset by using two best available diodes compared to using the best available bridge is surpassed by increased losses in transformer and wiring, the result is increased overall loss. I don't have any solid data at this point, but if you're cutting 2W in diodes, but increasing loss by 5W between the primary side input and input of diode, you're doing more harm than good in terms of total conservation not to mention requiring non standard 3 wire branch circuit is required to the unit rather than than standard 2 wire for condensing units.


Quote:
The idea of using "HVDC" for residential power distribution is really about new construction, not retrofitting. It is mostly of interest in off grid homes, not so much on grid.
Please take this off topic matter to your own thread. The thread specifically says the effect on power systems. Not battery powered self-contained devices or "off grid" LVDC utilization applications.

When Con Edison removed the revenue loss leading DC service, it didn't change the customer equipment. It simply relocated the burden of power conversion equipment onto customer owned equipment on customer premises.

MVDC transmission for irrigation and rural use shown in second diagram does have the advantage that power can be supplied directly to customer owned rectifier at 3 phase 7.2/12kV and avoids unbalanced load on the feeder associated with L-N loads. This can be carried over 12kV MVDC line and let the customer deal with the cost of 12kV to utilization voltage DC-DC facility and "PoL" VFD for pumps and homes.

Obviously the huge advantage is that conversion losses in equipment located past the medium voltage feeder including the rectifier loss is billable charge and customers bear the cost and repair bills of fragile solid state static converters. Changing the point of metering doesn't change the energy efficiency. It minimizes the amount everyone else have to subsidize to power up those middle of nowhere rural users.

If there's a windstorm and tree branches hit the MVDC private line and the unreliable solid state static converter goes poof, they get to replace it on their own dime.


Last edited by ICanHas; 08-31-14 at 10:58 PM..
ICanHas is offline   Reply With Quote
Reply


Tags
embedded systems, harmonic distortion, power electronics, power quality, vfd

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 07:56 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design