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I was just wondering about this same issue: of inverters being used
to support the grid. Just as charge controllers reduce their output
current as the voltage reaches absorption voltage, I was thinking
that GT inverters could do the same thing, instead of just shutting
off, and not reconnecting for at least 5 minutes.<br>
In Hawaii, with PV penetration on the grid as high as 15%, the
utility asks us to widen the voltage operating window beyond IEEE
specs, as they've found that when they have a low voltage line
condition, the PV systems actually help, and they don't want them to
shut off too soon and add to the problem.<br>
I could see a new generation of inverter specs beyond UL1741, that
was part of a smart grid controlled by the utility. They could
extend the operating window when needed to keep the grid more
stable. As subsidies dry up, this could be a future selling point,
especially if it offered the customer a more stable conditioned
power supply. Also be nice for the customer to get paid extra for
this emergency peaking capabilities, just like the big generating
facilities. It might even make GT w/ battery backup more cost
effective, if you could sell some battery amp-hrs at $1/ kwh every
once in a while.<br>
<br>
Ray Walters<br>
<br>
On 2/4/2012 7:05 PM, <a class="moz-txt-link-abbreviated" href="mailto:boB@midnitesolar.com">boB@midnitesolar.com</a> wrote:
<blockquote cite="mid:4F2DE3ED.6000009@midnitesolar.com" type="cite">
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<br>
Sounds like a voltage source (and sinking) inverter to me.<br>
<br>
These types can cause current distortion which the UL1741 / IEEE
1547 specs try to prevent.<br>
<br>
Apparent must be able to turn that mode on and off I would
imagine. It's not too difficult to do. No wonder<br>
they talk about micro-grids.<br>
<br>
The old Trace SW series was a voltage source inverter, even when
grid tied and is basically why they had<br>
to add that extra inductor box between SW and the grid when
selling. It could actually help the grid wave-<br>
form voltage if it was distorted because of non-linear loads.<br>
<br>
boB<br>
<br>
<br>
<br>
<br>
<br>
On 2/4/2012 5:26 PM, Comet Systems wrote:
<blockquote
cite="mid:CAG6C1qn=XcPjF8=BP1j=U6FbkBx49yT4PBJzr2pscjs9M7uedw@mail.gmail.com"
type="cite">
<div>As I understand the issue they claim to be able to address,
the utilities often need a source of reactive power close at
the system delivery points, the customer sites, because
reactive power does not transmit well through the lines and
transformers and uses up transmission resources better used
for real power. The reactive power is used as a method of
voltage control. </div>
<div>Therefore, it is reasonable that the utilities would pay a
premium for a reactive power source which would be close to
the customers and under their control. The idea has some merit
and could be a significant direction for solar pv, but whether
an electronic inverter can adequately generate reactive power
at will, to act as a compensation device and whether that is
the highest and best use for that power source is to be
demonstrated. Interesting idea, though.</div>
-- <br>
Chris Mason
<div>President, Comet Systems Ltd</div>
<div><br>
</div>
<br>
<br>
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