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Thread: Solar PV panels
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face picon face BY : RussellMc email (remove spam text)


                  BCC Ken - comments?

On 23 June 2016 at 11:32, David C Brown <RemoveMEdcb.homeKILLspamspamgmail.com> wrote:

{Quote hidden}

​_________________

The installation company is ~= correct as long as the inverter is designed
correctly.
The inverter will produce maximum power from the DC input (if set to do so).
The inverter can configure its voltage and phase angle such that it will
transfer excess power to the grid if excess power is available and allow
power drawer from the grid i Pinverter < Pload. . ​
​By ...

​________

E&OE.
No guarantee that this is fully correct.
As it in part MAY disagree in some degree with Brent it's probably ​in some
degree wrong (probably for both  correlated and non correlated versions of
some)
* I changed disagrees' to 'may disagree'  as I'm talking about V and he may
have been talking about I.
We appear to still not be in full agreement.  eg I say max power at V +/-
90 lead/lag of Vgrid. .

A simplistic but useful look at power transfer is given by:

V1 = invertervoltage
V2 = grid voltage
X12 or just X is coupling impedance between inverter and grid. This usually
includes a physical inductor or sustem inductance.
Delta = d is phase angle between inverter and grid.
sind = sin(d) , cod = cos(d)

Real power transfer = V^2/X = (V1 x V2)/X x sind
So may transfer occurs at d = 90 degrees.
V1 leading V2 gives max real powerexport.
V1 lagging V2 gives max real power import.
Power is also controllable by varying V1.
[Murphy suggests that getting V1 leading V2 may require V1 > V2 but that's
a technicality].

Imaginary power transfer = V1^2/X - (V1 x V2)/X x cosd

As cosd = max = 1 when sind = 0 and d=0, pur  reactive power max occurs
when V1 and V2 are in phase BUT if V1 = V2 you then get zero reactive
power. By then altering V1 relative to V2 you generate negative or positive
reactive current in X and thus overall reactive power.

______________

I dislike "slideshare" pages but this slide set gives the simplest
treatment I found.
Slide 5 says much as above but other slides are variably useful

         http://www.slideshare.net/niteshjha3705/grid-tie-inverter

Pages 52-55 here say similar
MODELING AND ANALYSIS OF A PV GRID-TIED SMART INVERTER’S SUPPORT FUNCTIONS
Thesis 2013m 112 pages

 http://www.slideshare.net/niteshjha3705/grid-tie-inverter

Nicish TI grid tied microinverter reference design with software available
as a module in the free development suitye
Grid-tied Solar Micro Inverter with MPPT
          http://www.ti.com/tool/TIDM-SOLARUINV

ST 3 kW equivalent - 65 pages but maybe no software

             <
http://www.st.com/content/ccc/resource/technical/document/application_note/0b/16/e1/a7/0e/db/49/09/CD00253868.pdf/files/CD00253868.pdf/jcr:content/translations/en.CD00253868.pdf
>




*Relevant*


Mainly for schematic.
One topology of many

        http://solar.smps.us/grid-tie-inverter-schematic.html


IEEE 2012
6 pages
Reactive Power Control of Single Phase Grid Tied Voltage Sourced Inverters
for Residential PV Application


http://www.ele.utoronto.ca/wp/wp-content/uploads/2014/11/C/X_Zong-C39.pdf


Google: Simplified Reactive Power Control for Grid-connected Photovoltaic
Inverters

*Less relevant:*


https://yhipower.co.nz/downloadhandler.axd?type=2&id=100246&ins=1

http://www.cleanenergyministerial.org/Portals/2/pdfs/A_Guidebook_for_Minigrids-SERC_LBNL_March_2013.pdf


Am I starting to sound like Brent?
:-)


       Russell
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