spaco wrote:

My son and I are planning to build and operate woodgas cogeneration
plants at our homes. We will be delivering as much power as we can
(20KWH to 45KWH)

(...)
Sounds like you need a grid tied inverter (synchronous inverter)
Homepower.org http://www.homepower.com/article/?fi..._pg120_QandA_1 recommends the sma-america brand

The ST36 will pump up to 45kw back into the mains
http://download.sma.de/smaprosa/date...yer-042007.pdf

They have a range of smaller units available too.

Also check out the alt.energy.homepower newsgroup.


--Winston

Dont you just love people who abuse Usenet date stamping of messages to
leave spam up for weeks.

On Mon, 30 Jun 2008 08:16:12 -0500, spaco wrote:

My son and I are planning to build and operate woodgas cogeneration
plants at our homes. We will be delivering as much power as we can
(20KWH to 45KWH) to the grid in 8 to 10 hours batch mode runs, one day a
week. We know that several companies produce sync/life safety systems
for solar and for wind, but we can't find any providers the do it in our
size range for internal combustion engines. At worst we'd have to
produce DC and then go with the solar or wind type system, but that's
expensive, messy and inefficient.
It is frustrating. When I do find somebody who sounds as if they
might be "the one" they have only huge systems. The two electric
utilities that we have to deal with don't even know.
Does anybody on this ng have any leads?

Pete Stanaitis
-----------------------

Doing this with a synchronous machine would be damn near impossible,
because you can't easily control the engine speed that tightly. At best
you'd be presenting a really odd load to the line.

Have you considered using an induction machine? These used to be used
for wind power because all you have to do to get them to deliver power to
the line is drive them above synchronous speed.

Dunno if the power companies would like it, though.

Failing the above (whacky) idea, it's go to DC and back to AC.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

"Tim Wescott" wrote in message
...
On Mon, 30 Jun 2008 08:16:12 -0500, spaco wrote:

My son and I are planning to build and operate woodgas cogeneration
plants at our homes. We will be delivering as much power as we can
(20KWH to 45KWH) to the grid in 8 to 10 hours batch mode runs, one day a
week. We know that several companies produce sync/life safety systems
for solar and for wind, but we can't find any providers the do it in our
size range for internal combustion engines. At worst we'd have to
produce DC and then go with the solar or wind type system, but that's
expensive, messy and inefficient.
It is frustrating. When I do find somebody who sounds as if they
might be "the one" they have only huge systems. The two electric
utilities that we have to deal with don't even know.
Does anybody on this ng have any leads?

Pete Stanaitis
-----------------------

Doing this with a synchronous machine would be damn near impossible,
because you can't easily control the engine speed that tightly. At best
you'd be presenting a really odd load to the line.

Have you considered using an induction machine? These used to be used
for wind power because all you have to do to get them to deliver power to
the line is drive them above synchronous speed.

Dunno if the power companies would like it, though.

Failing the above (whacky) idea, it's go to DC and back to AC.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
The only speed control required is to get the machine initially
synchronized. Once a synchronous machine is connected to a much stiffer
source/load such as a power grid the speed is locked to the grid. The only
requirement from the prime mover is to maintain a positive torque output at
that speed. The power output will be proportional to the torque and can
become zero or negative if the prime mover torque is reduced but speed will
never vary. The alternator will become a motor if necessary to maintain the
speed. The governor becomes non-functional if it is only speed sensitive as
varying the fuel only controls the load. You can just adjust the fuel for
the desired load and leave it there.

Don Young

My son and I are planning to build and operate woodgas cogeneration
plants at our homes. We will be delivering as much power as we can
(20KWH to 45KWH) to the grid in 8 to 10 hours batch mode runs, one day a
week. We know that several companies produce sync/life safety systems
for solar and for wind, but we can't find any providers the do it in our
size range for internal combustion engines. At worst we'd have to
produce DC and then go with the solar or wind type system, but that's
expensive, messy and inefficient.
It is frustrating. When I do find somebody who sounds as if they
might be "the one" they have only huge systems. The two electric
utilities that we have to deal with don't even know.
Does anybody on this ng have any leads?

Pete Stanaitis
-----------------------