More like “could work let us know how it goes!” Brian
> On Nov 3, 2019, at 10:01 AM, Mark Frye <ma...@berkeleysolar.com> wrote: > > OK Brian, > > So I think you are confirming that monitoring AC side voltage is an > acceptable way of deciding when to disconnect the GT inverters. > > With my parts list, I have a delay time that would hold the GT inverters > off-line for some period of time (I would probably set to 1 hour) before > coming back on line after tipping off. > > > Mark > >> On 11/3/2019 9:53 AM, Brian Mehalic wrote: >> With frequency-on/off, frequency power control, or other “inverter >> integrated” control based on battery voltage/state of charge there is also >> control in regards to when the ac coupled inverters come back on. And yes, >> this is definitely needed to prevent overcharge (or get three-stage charging >> from the AC coupled system). Of course if it doesn’t work, yes the bus >> voltage will rise and trip the BB offline. >> >> AC bus voltage will go down as soon as the ac couple inverters are kicked >> off, so if that’s your measured value unless your control system has a delay >> or other component to control reconnection and charging i think it could >> essentially chatter off and on and off and... >> >> Brian >> >>>> On Nov 3, 2019, at 9:38 AM, Mark Frye <ma...@berkeleysolar.com> wrote: >>> >>> Hi William, >>> >>> Thanks, you bring up issues that are important to me here. >>> >>> In particular, my situation is that the GT inverter is inter-tied a couple >>> sub panels upstream of where I want to put the BB inverter. The distance is >>> long, so I am looking for a solution where I don't have to run a cable >>> between the two. >>> >>> In general, I do wonder about using AC line voltage rise to take the Gt >>> inverters off line. The main goal is to prevent excess voltage at the >>> battery, so monitoring battery voltage is most direct, and there are simple >>> solutions for that. >>> >>> Is AC line voltage a suitable metric for achieving the same goal? >>> >>> Here is where I could use Wrench knowledge to confirm my thinking, that >>> being: >>> >>> - With excess energy in the system, the charger moves it into the battery, >>> raising it's voltage until it reaches it high charging voltage set point >>> >>> - Once the battery reaches it's high voltage set point, the charger stops >>> putting energy into the battery >>> >>> - With no other place to put the excess energy, the AC voltage rises >>> >>> Am I getting this right, the reason to disconnect AC coupled inverters when >>> the battery if full is not to prevent the batteries from being overcharged, >>> but rather to prevent the AC line from becoming unstable? >>> >>> I am hoping this is correct and that with $200 of industrial grade devices >>> from Digikey I can implement a robust control that will disconnect the GT >>> inverters before the AC line goes so high that the BB inverter faults. >>> >>> Mark >>> >>> >>> >>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> List Address: RE-wrenches@lists.re-wrenches.org >>> >>> Change listserver email address & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> List-Archive: >>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html >>> >>> List rules & etiquette: >>> www.re-wrenches.org/etiquette.htm >>> >>> Check out or update participant bios: >>> www.members.re-wrenches.org >>> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> www.members.re-wrenches.org >> > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
