[RE-wrenches] Generator Controlled Mini Grid

jay peltz jay at asis.com
Tue Feb 12 19:21:12 PST 2013


Hi guys,

You might look into AC direct hydro controls.  Thompson and Howe make them 
they are designed to keep both frequency and voltage within tolerance with dump loads.

jay

peltz power
On Feb 12, 2013, at 5:13 PM, Glenn Burt wrote:

> Sounds like a job for a directional relay - utilities use them.
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
> Sent: Tuesday, February 12, 2013 7:29 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Generator Controlled Mini Grid
> 
> Hi Kevin,
> 
> Right now we are in the stages of investigating what is possible.  The
> design is for 10kW of PV - inverter capacity.  The inverters will be Sunny
> Boys, so if may be possible to regulate them.
> 
> We haven't decided on a generator yet.  A dump load sounds like a good way
> to absorb excess power.
> 
> Have you heard of electronic controls to facilitate this process?
> 
> Thanks,
> 
> Drake
> 
> 
> At 03:43 PM 2/12/2013, you wrote:
>> Hi Drake,
>> 
>> Further, can you give us an idea what scale you are talking here - ie 
>> PV and Generator capacity? With your mention of inverter/generator if 
>> your talking ie the small Honda EU6500 or such?
>> 
>> I did think of another project that I am involved with - it's a remote 
>> community with conventional diesel power plant (100 kW day,
>> 30 kW night). There is 27 kW of distributed PV over 5-6 different 
>> homes, using the older Xantrex GT inverters. It's not the most 
>> elegantly designed solution - as it's possible for PV output to be 
>> greater than the load which causes shutdowns. In that case, a dump load 
>> is kicked in briefly and that bumps the frequency enough to kick the GT 
>> inverters offline, and then the cycle repeats.
>> 
>> Not my design, but it does work and has been this way for several years
> now.
>> 
>> Kevin
>> 
>> -----Original Message-----
>> From: re-wrenches-bounces at lists.re-wrenches.org
>> [mailto:re-wrenches-bounces at lists.re-wrenches.org]On Behalf Of Drake
>> Sent: February 10, 2013 10:46 AM
>> To: RE-wrenches
>> Subject: Re: [RE-wrenches] Generator Controlled Mini Grid
>> 
>> 
>> Hi Kevin,
>> 
>> Thanks for the Eigg video.  What a great place.
>> 
>> I didn't see evidence of any AC coupling of inverter produced AC to a 
>> generator produced mini grid.  I understand this is being done in a 
>> homebrew manner by some.
>> 
>> The current wisdom on the issue is that the less the PV contribution to 
>> the generator supplied grid is, the easier.  It would seem that if a 
>> grid tie inverter output could be regulated, using Sunny Island type 
>> controls, it should be possible to have a small inverter generator 
>> create a mini grid that could be fed by PV.
>> 
>> A system featuring this type of technology was linked in a posting on 
>> this list some years ago, The link seems dead now.  In that case a 
>> large generator was feeding a number of houses, and PV was fed into the 
>> system.
>> 
>> The reason for this interest is that battery backup systems are much 
>> more expensive than generators.  We need to find a way to utilize PV 
>> arrays during outages without the expense of battery backup systems.
>> 
>> Drake
>> 
> 

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