Using field control regulation in hydro system

 

Can someone explain the downside of using automatic field control
regulation on a hydro system? I'm using an older 12V Harris hydro
system and would like to be able to automatically regulate power output
of the alternator without having to provide a diversion load.

According to a Harris manual I found on the web, automatic field
regulation "cycles both alternator speed and temperature, which can
create a problem in high head systems or in moist sites where
condensation on electrical connections accelerates corrosion". I think
I understand the condensation issue related to temperature changes, but
don't understand how high head causes problems.

Any recommendations/pointers on circuit design for such a controller?
Thanks,

Even with diversion load or field control regulation, does the hydro
system output need to be fed through a charge controller? In my
particular case, especially this time of year, hydro is our main source
of power, PV secondary.

-Jerry

 

Jerry wrote:

I only know half of this one.

With diversion your generator runs at high power outputall the time
theres enough water flow, and that diversion load can be used for
something - perhaps water heating etc.
With regulation, the gen only outputs what's demanded at the time, so
the thing will run much cooler, with less current flow. What I know
about motors tells me that would last better, but yes it means temp
will change according to load, instead of being maxed out all the time.
Periods of lower temp surely would mean less corrosion I would think.

I'm sure someone with more experience of hydro can fill in the missing
points.


NT

 

When you back off the regulator to produce less power, the generator will
speed up if the water flow remains the same.  Not acceptable for AC, but I
guess it is OK for DC if you don't exceed the rotational speed capabilities
of your machine. Let me see now... my armchair physics.... if the machine
speeds up, then your output voltage will also increase, requiring even more
reduction in field current to keep things regulated.  At some point your
turbine or water wheel will lack efficiency to spin any faster and will
reach equilibrium with your load.

It appears easier and more responsive to divert load energy rather than
trying to regulate water flow.    I hope we can get confirmation of this
from someone who has BTDT.

 



Most of the Micro and Mini Hydro Generations Systems around here have
either DC Output with no overspeed control by let the rpm equalize
to the maximum of the turbine drive, or if AC have a Petcock Feedback
System that regulates waterflow into the turbine. It isn't really all
that hard to do with good Linear Actuator and a Zero Crossing Detector
feeding some simple feedback and drive components.

Bruce in alaska
--
add a <2> before @

 



That's my read too.

But if just using field control on a DC unit, you waste a lot of water.  Not
much a problem if just using 'run of river' situation, but with no way to
control the flow of water, and overspeed *might* be a problem, and you waste
all that water if you're using a storage dam.

Might combine field control with a slower responding water control system.
As the load drops and field control maintains voltage, let the higher RPM
feed into a slow-acting water valve to gradually reduce the water flow.

If water waste or overspeed are a concern.

daestrom