[RE-wrenches] Apparent Power's reasonably smart inverter

[Hilton Dier III]

Chris,

I just read a white paper on the Apparent Power site, and it appears 
that they have an inverter that is one step smarter than your average 
bear. The key quote:

"The inverter changes the DC input from the solar panels to AC, senses 
the phase angle lag or lead on
the output line, and compensates by changing the phase angle of its 
output current with respect to the
grid voltage, until the current and voltage are in-phase."

So it can sense how far off the voltage and current curves are and push 
in a wave form combo that attempts to get the grid waveform back to 
unity power factor. How successful it would be depends on the size of 
the solar/inverter array compared to the other loads and generators on 
the grid, but it is pushing in the right direction.

I used to work for Northern Power Systems in Waitsfield, VT. While I was 
there they came up with a really smart inverter that did the same thing 
only more so. I think the working name was the Power Router. It read the 
grid waveform about 1000 times per second and modified its output at the 
same rate to attempt to create a perfect unity factor sine wave on the 
line. With enough Power Routers on an isolated grid you could see 
garbage wave turned into lab grade sine wave. Sadly, it never became a 
product.

This technology is more simplistic, but I'd say you have a good case to 
bring to your utility. Send their engineers to the Apparent Power 
website and let them geek out with the white paper:

http://www.apparent.com/downloads/TheMathematicsOfDynamicPowerManagementOnTheGrid.pdf

Remember that with utilities it's always a fight until they realize the 
benefits.

Best,

Hilton Dier
>> Ray,
>> The idea that the utility in an island is seeing an advantage to
>> having PV on the grid is a huge concept for me.  As  I am based in a
>> small island with a utility that is scared of solar pv installations,
>> this concept is tremendous ammunition for me. I am also fascinated by
>> the idea of PV installations as a corrective power source, the
>> possibilities for this are tremendous.
>> If there is any more information anyone can offer on the impact of PV
>> on an island grid, I would be very interested to hear.  I am going to
>> write an article on my blog and in print on how other islands are
>> benefiting from solar, so anything you can tell me will help to build
>> this story.
>>
>> Chris Mason
>>
>>

-- 
Hilton Dier III
Renewable Energy Design
Partner, Solar Gain LLC