Re: [microhydro] Grid Synchronization
- View SourceSagar:
I do not have any paper or electronic files I could send to you, though I
have done a lot of synchronization of Micro Hydros to another higher power source or
Depending on the generator, the problem can be quite simple.
If the Generator is an induction Motor as a generator, the procedure :let
the Turbine rotate the Motor,( NO capacitors connected yet ) close the needed RPM , then apply the
GRID power ( single or 3 phase) to the motor, if the RPM is low, the motor
may start as a motor, if the RPM is high as a generator, --
The Turbine will increase its RPM to the RPM+SLIP to set the Induction Motor into a generator
You may use AC motor running capacitors to adjust the PF, as well, if the
head and the turbine diameter were not accurately analyzed, the need to adjust the jets to set the RPM
for best PF .
If the generator is an actual generator( synchronous motor with AVR ) then
you may need an additional arrangement, You need Frequency phase synchronization
and the possibility of adjusting the AVR voltage to equate the generator
voltage to the GRID voltage that will vary depending on the loads.
The phase synchronization is done with a simple circuit detecting the
Generator and the GRID ZERO crossing and Polarity that when both are close
to each other ( around 5 degrees) the auto connection is done automatically.
If You have access to the AVR, a simpler way is to "DISCONNECT" the AVR for the generator to drop its voltage, then you do the starting procedure as for the induction motor as a generator -- and when connecting the GRID the AVR is as well connected, it may take 3 or 4 Hertz to be fully operational without any heavy currents.
This way you can connect two sources with one, as the master and the other,
as the slave, also if you are adding two small micro hydros for greater
power, may the need to add two current transformers to share either equally
or a % of one greater than the other, in this case the need to have the AVR
adjustable of one or both to accomplish the procedure.
As I understand it , the Nepal GRID voltages are quite wild and not well regulated, in the past I have sent designs of automatic adjustable transformers circuits to implement voltage regulators -- also the neutral wire, OFTEN, it is not Neutral but QUASI-HOT - in some cases reports as high as 70 to 100 volts .
How is this problem in your area and where are you located ?.
----- Original Message -----
From: Sagar Mani Gnawali
Sent: Tuesday, May 31, 2011 1:29 AM
Subject: [microhydro] Grid Synchronization
We are working for Grid Synchronization of Micro Hydro to the
national grid. This project is very much important for sustainability
of the existing micro hydro.
Is any body has worked for Electronic Governing System ( Similar
function of Mechanical Governing System) of water flow to the Penstok
by sensing the load status of Generator?
I am eager to learn and implement soon this project in Nepal through
my organization Alternative Energy Promotion Center. Would you please
support me by providing your knowledge, documents and other way of
Sagar Mani Gnawali
Alternative Energy Promotion Center
Mobile No. 0977-9841803113
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