Re: Fwd: RE: [a-w-h] MPPT -- how large is the benefit?
MPPT is good for Solar, Wind and Hydro Small systems. 20 to 30 % improvement
in harvested energy.
MPPT is ideal for Wind Mills since it allows to harvest the peak power
available at any moment BUT for this one needs that the generator is not
clamped with a battery but allowed to rotate to its peak RPM ( within the
RPM limitations of the mill) --
One thing is that one can attain about up to 90 % efficiency if the
generator is properly matched and for that you need MPPT controller.
With a clamped wind mill ( battery direct charging) the maximum looks like
is around 49-53 %
For low power systems : The laws are simple : measure Generator voltage and
start loading it, measure generator, increase load, measure generator,
define energy slope for increasing or decreasing loading -- this goes
up/down and the circuit being analog or digital follows a curve always going
to the apex of the energy available at any moment, time is a factor as well.
I have included an attachment of a small MPPT charge controller for your
----- Original Message -----
From: "meed7" <meed7@...>
Sent: Wednesday, November 30, 2005 4:04 PM
Subject: Re: Fwd: RE: [a-w-h] MPPT -- how large is the benefit?
> In my experience, photovoltaic MPPTs can boost overall energy output
> of a PV system by 10-25%, based on exploiting the difference between
> the load voltage and a PV cell's actual operating voltage --
> especially in cool conditions.
> What sort of corresponding energy boost are wind turbine MPPTs able
> to provide -- assuming, since this is the Small Wind group, a fixed
> pitch rotor and a permanent magnet alternator?
> I assume that a wind MPPT has the goal of operating the blades as
> close to their optimum L/D as possible in a range of wind speeds.
> What sort of control laws are used to achieve this goal?
> --- In email@example.com, Darryl Thayer
> <daryl_solar@y...> wrote:
>> MPPT in a wind machine controller is a method of
>> optimazation, where the controller loads the wind
>> machine to extract the maximum power at the given wind
>> speed. The usual method for a PMG wind machine is to
>> sense the output and adjust the impedence of the load
>> to maximize this condition. As the wind changes load
>> impedence is continously adjusted. On the New Jacobs
>> the field current is adjusted passivly to make a cube
>> law (on RPM) load adjustment. For PWM machines I am
>> not allowed to comment, however contact the
>> manufactures as some models have this feature. The
>> first controller, I know of, to do this was the
>> windyboy from SMA. This controller MUST be matched to
>> the wind machine and is grid tied.
>> --- martin fleming <martinf@f...> wrote:
>> > To: "'Darryl Thayer'" <daryl_solar@y...>,
>> > <firstname.lastname@example.org>
>> > From: "martin fleming" <martinf@f...>
>> > Date: Mon, 28 Nov 2005 07:59:48 -0800
>> > Subject: RE: [a-w-h] MPPT
>> > Hi All,
>> > Could somebody please explain what MPPT is--both
>> > theoretical and
>> > practical examples would be great.
>> > Thanks,
>> > ~martin fleming
>> > BTW, Last night was a great wind production night.
>> > 20 kw steady output
>> > for about 12 hours straight. I used to curse those
>> > winds.
>> > Darryl said:
>> > Your configuration depends upon what wind machine
>> > you
>> > choose. Some wind machines have MPPT (Maximum Power
>> > Point Tracking) and direct grid tie, other do not.
>> > (I
>> > am not allowed to tell you which I think are best on
>> > List) If you choose a machine that is direct grid
>> > tied with MPPT this will give you the maximum
>> > electrical generation.
>> > If you build your own wind machine, it will probably
>> > be DC and not MPPT. In this case you will need at
>> > least a small battery set and a DC to AC Grid tied
>> > inverter. ( Again I can not give you a
>> > recommendation
>> > on list)
>> > Darryl
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>> Access over 1 million songs. Try it free.
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