Induction Generator Info needed

[dithomas]

I am in need of information concerning the starter and power controler for a 300kW 480 VAC indcution generator system.

The generator will be driven by a hydro turbine and directly connected to the power grid once at synchro speed. The power control must would output s 4-20ma signal to turbine valve.


Dan

 

[byrdj]

google search for "hydro governor induction generator" found this. It may be helpfull

http://home.carolina.rr.com/microhydro/induction.html

 

[dithomas]

Thanks byrdj,

I had done the usual google search prior to my Eng-Tips inquiry and found the same site.

I am searching for a more technical presentations on the topic.

Dan

 

[3winding]

What do you mean by starter? I assume you are starting the generator with the turbine and running it to sync speed?

You just need a speed switch to give a close command to a breaker and then a governor to control it. I have used Woodward 2301D on many induction generators and they give great control. A small PLC integrated with it to do some general housekeeping and you have your system. Induction generators are very forgiving when it comes to synchronizing. A few rpm here or there doesn't matter.

 

[dithomas]

Thanks 3winding,

I say starter because I assume that one would use an across the line starter contactor (what you are calling the breaker) that would close to connect the generator to the grid once the turbine brings it to synchronous speed.

You answered one of my question with your reference to the Woodward 2301D.

The proposed machine is to be approx 300kW and 480 volts.

I have requested specific turbine and water valve information and have not yet received it.

 

[Skogsgurra]

A very simple system using a Siemens LOGO! PLC is now being tested in a small hydro-electric plant. It uses a proximity switch to pick up pulses from a coarse toothed wheel and the built-in comparator to connect to grid when speed is just above sync. It disconnects when speed is close to sync (to prevent motoring) and it also has outputs to increase/decrease water flow. The comparator output also closes water when speed gets too high to avoid overspeed when generator loses grid.

A cheap and flexible solution with lots of potential in it. There is also a lot of spare capacity in this EUR 150 (USD 180) PLC.

 

[3winding]

Also, you will need a protection relay. A Basler BE3-GPR or GPS-100 are economical choices for smaller units. There is a company called Thomson Technology that provides turnkey controllers, not sure if the do turbines though.

You may also want to add power factor correction capacitors, which need to have delay switching upon synchronzing to avoid counter torqures on your turbine.

 

[mc5w]

A cheap speed monitoring device would be a blower motor from an electric clothers dryer. This has a centrifugal switch contact that closes once the motor is up to speed to keep the heating elements from operating without airflow. You could belt about 2 or 3 of these. These are NOT precise instruments and you may have to build a test rig using a variable frequency drive and 3-phase motor to get the right belt ratios.

Gas clothes dryers theoretically use the same motor and contact to control the gas burner.

This may sound really primitive but it is cheap.

An alternate method is that Telemecanique makes some inductive proximity switches that sense the speed of a toothed wheel or a simple bolt that passes through a shaft or a fan blade. You can adjust these to change the contact threshold at a certain speed. You would need at least 2 of these, 1 to control the contactor and the other to close the water valve in the event of overspeed.

More expensive but more precise.

Mike Cole mc5w at earthlink dot net