I have a question about designing a solar-hydro energy system, as we ran into a problem in the implementation phase. We have 1 kW pv plant connected directly to a charge controller, and the 1 kW hydro turbine connects to it after a rectifier. The problem is that the charge controller draws as much power as it can from the turbine, making it stall.

The hydro turbine typically produces about 400 W, and when connected to the charge controller, it tries to produce the rated 1 kW, its frequency plummets and it stalls.

What options do we have to limit the power output of the turbine? Finding a cheap, off-the-shelf solution would be preferable but I wouldn't rule out building something ourselves.

Thank you for the help!

  • \$\begingroup\$ Why do you think limiting the power solves the problem? "the charge controller draws as much power as it can from the turbine, making it stall." is not true: if it stalls power output is 0. You want to maximize power output (i.e. find the operating point that yields most power), don't you? \$\endgroup\$ – Curd Oct 17 '19 at 8:07

MPT regulation occurs when the load impedance matches the output impedance of the PV array.

The PV is a quasi linear current source so the incremental impedance is the same as the load line PV , V/I= Zout or delta V/delta I = Z a negative impedance by definition.

MPT theorem states max power is transferred when Z is matched.

therefore your goal is to detect Z with a PD sensor to predict V/I and regulate Generator load to bridge cap Z load.

PWM with LC filter is probably the best way with current sensing to track the PD sensor current as the current limit. After startup, current limit with load regulated.

SCR control with slew rate phase control is another option. Motor soft start NTC devices , a last option while semiconductor NTC’s might be marginal rated on mF load. There’s always a soft charge relay bypass method that is viable too using heater wire.

So there are 5 solutions and the theory for a spec.


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