Hi Mac, We worked for a while building controls for one company in Oz doing small hydro, and I can share some observations, and things I learned coming from a solar background:
> My first question is can you run a power system from hydro direct in the 10 > -100 kW range? Yes, I believe this is common in that power range to avoid battery and BoS costs. A DC-coupled/battery-backed approach could be used where the water flow is seasonal or insufficient for loads, or where solar is added. > If so, how do you adjust for varying load? For smaller systems with "normal" (i.e., not "low-head") turbines, the water is pretty much either there or it isn't, so the turbine works with constant head. Typically, these are set up to run at full power, and a diversion load is used to regulate RPM (and frequency for AC systems). For AC systems, rotor/field current can be adjusted to regulate voltage, as you mentioned. For the DC systems we supported, we built our control algorithm to the turbine builder/installer's instructions, and rather than trying to MPPT the turbine as we would for solar, the controller was set to clamp the rectified turbine voltage to a fixed, user-adjustable value. At installation, after the nozzles and penstock were adjusted, the installer would manually adjust the turbine clamp voltage to maximize charging current, then leave the voltage there indefinitely, in effect doing MPPT once. Our controller used a diversion load to regulate the turbine voltage/RPM once the batteries were full. As you scale things up, the diversion load approach would seem to get a little silly, so adjusting the flow rate as Darryl suggested would seem to be the better, if more complex approach. Based on the info you gave for your customer's installation, it seems like the automatic transfer switch is a great idea, but it's probably not worth trying to DC-couple it if it's working well when not clogged. For some background and reference, here are some links to AC and DC hydro products from the company we worked with, and an excellent writeup of a personal small AC hydro installation that talks through the transmission and control issues in great detail: https://www.platypuspower.com.au/ https://ludens.cl/paradise/turbine/turbine.html https://ludens.cl/Electron/picelc/picelc.html https://ludens.cl/Electron/AVR/AVR.html Again, thank you Wrenches for all the knowledge you share. Alex MeVay Blue Sky Energy * http://www.blueskyenergyinc.com Genasun * http://www.genasun.com _______________________________________________ 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
