omron

[Shaun Burgess]

hi all .. its blowing a storm here and i notice the omron controller hitting the max voltage an odd time . but the relay seems to click closed for a second then open and then close and stay closed for around ten seconds .. i notice the hysteresis was set at around 40%.. in robs drawing its 20%.. i turned the omron to 20% and the operating time was set to min value but of course the wind died down a bit so am not sure if it stopped the on of on .. the controller worked find in testing ..

[John Szegda]

Hello Shaun,

My OV Controller went on line Saturday and worked great, except the chatter. Rob instructed me to set the Hysteresis in small increments until I was satisfied with performance. So I'm starting at 30%, but like you, the wind died. For the past two weeks it's been blowing 20-35 MPH.

John

[Andy Rhody]

We all have different wind generators. Mine is a 2000 Watt Chinese rated @ 72 volts and was designed to charge batteries. Rob figured out how to make it work for grid-tie.

My Omron settings are:

SV. about 24%. It dumps @ 180 volts.

HYS. 20%

T. 0

When it goes into dump mode, it usually stays there for about 11 seconds.

[Rob Beckers]

John, to get a better idea of what's happening you would have to measure the phase-to-phase voltage of the turbine (very carefully, these are dangerously high voltages!). It would show you what the voltage is when the dump load clicks on, and what's happening to make it click off again.

It could be a dump load size issue as well; if your dump load resistance is very small in relation to the size of the turbine and the voltage that it switches at, it could be putting the brakes on the turbine in a big way when it engages. Slow down the turbine and the voltage drops. Once under the set point of the Omron, minus the hysteresis, and it will switch back to inverter. For example, if set at 200V with 30% hysteresis: The Omron will switch to dump load at 200V phase-to-phase (AC), and switch back to the inverter at 0.7 * 200 = 140V phase-to-phase.

Keep in mind that for a turbine that's working well, you want the dump load only to come on occasionally (unless you have a grid failure), to take care of those voltage spikes when the wind suddenly gusts hard and the turbine doesn't have time to furl. Your turbine isn't making you any money when it's on the dump load! So, ideally it shouldn't be running very long on dump load at all when it comes on. Either the wind dies down, or the turbine furls itself out of the wind enough to drop the voltage and switch back to the inverter. Normally the inverter should keep enough of a load on the turbine to keep it from going too high in voltage, most of the time.

Of course, this only works if everything is sized just right: The inverter needs to have a proper MPPT table for the turbine, the dump load needs to be the right resistance, the set point for the Omron relay (where it switches) needs to be right.

Your mention that the relay switches for a second, switches back, and then goes to dump load for a longer period has me thinking there may be something wrong (wiring?). Unless the wind just happened to be that way, and you had two quick gusts...

-RoB-

[Shaun Burgess]

hi . the wind was up agin today . i turned the hys to around 30% and is working well now . i turned the dump up a bit to . the turbine only starting hitting the max voltage since i repaired the ground fault it one of the phases which happened to be the one of the two phases controling the omron . well i think i was losing some volts there leaving the omron coming in later then now.. now i could be totaly wrong.. all i can say since the ground fault repair the turbine is running a lot better. it was like the inverter was holding it back .. and inverter now powers off when theres no wind .. happy days