synchronize genset with utility - load flow
synchronize genset with utility - load flow
(OP)
Hello,
I have a question regarding synchronizing a small generator with the utility. I have a 15kW genset that a client wants to sync to the utility feeding his building. The synchronization can be done using a contactor and a synchronizing controller (like easygen or woodward EGCP-2). My question is more based on theory of operation. Will the generator be able to feed the building loads (about 8kW), or will the utility be providing for all the required loads? I did a very quick load flow analysis on etap and it showed my generator feeding 0kW, 0kvar, while the utility covered the entire load. Is there any way to ensure my genset will be providing at least 50% of the building load, while the utility covers the other 50%?
Thanks.
I have a question regarding synchronizing a small generator with the utility. I have a 15kW genset that a client wants to sync to the utility feeding his building. The synchronization can be done using a contactor and a synchronizing controller (like easygen or woodward EGCP-2). My question is more based on theory of operation. Will the generator be able to feed the building loads (about 8kW), or will the utility be providing for all the required loads? I did a very quick load flow analysis on etap and it showed my generator feeding 0kW, 0kvar, while the utility covered the entire load. Is there any way to ensure my genset will be providing at least 50% of the building load, while the utility covers the other 50%?
Thanks.






RE: synchronize genset with utility - load flow
RE: synchronize genset with utility - load flow
Thank you.
RE: synchronize genset with utility - load flow
The issue is if you want a defined split in the load, or will a fixed generator output surfice. A defined split will require more equipment than a fixed generator output.
RE: synchronize genset with utility - load flow
RE: synchronize genset with utility - load flow
In parallel to grid the easyGen or the EGCP can either operate in Baseload or Remote Load control modes. If the site loads are stable or always above the capacity of the installed genset when you want the unit on line, Baseload will work fine for most situations. If you want to perform some type of load following, to minimize import and prevent any export, the controls get a bit more complex. VAR control can be done with either Woodward unit, provided the voltage regulator on your little generator will interface properly with them. You could run the voltage in droop, as long as the AVR will manage it properly, most small sets don't in my experience.
Hope that helps, Mike L.
RE: synchronize genset with utility - load flow
An alternative may be to look at a large UPS, 100 amps more or less, and put all or part of the building load on the UPS. Then use the genset to charge the batteries.
Just for fun, lower the system voltage a little in ETAP. Say about 10% to simulate heavy grid loading. Look at what happens to your reactive current and gen-set power factor. You may have to consider a more sophisticated (and more expensive) AVR to follow the grid voltage and lessen swings in power factor and reactive currents due to grid voltage variations.
Bill
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"Why not the best?"
Jimmy Carter
RE: synchronize genset with utility - load flow
In the bigger picture, you set the genset to output a certain power and it goes out into the power wires. The power leaving the genset doesn't know the difference between the customers building or another load 100's of miles away. The fact that you're confused about what will really happen because Etap isn't modelling it correctly points out that you might not be the correct person for this job. You should likely seek help, and this forum doesn't count.
To get back to the complete basics, control the throttle to vary the kW output and control the field voltage to control the kVAR output. So, as Waross already mentioned, you need a control system (AVR) that can accomplish both of these. I highly doubt that 15kW genset built for stand-alone duty has the necessary controls as is.
Also, are you leaving out some detail such as not being able to or not wanting to supply power back into the grid? I would expect you could set-up equipment to measure the building power and then use those readings as an input to a decent genset controller which would ensure the genset output tracks the building power demand.
RE: synchronize genset with utility - load flow
- Synchronization will be done by using an EGCP-2 controller, in conjunction with a simple contactor (yes interface may be interesting).
- All required relays (ANSI #'s 50/51, 50G/51G, 25, 27, 47, 59, 81, 32, 46) will be internal to the EGCP-2, and will send a signal to a shunt trip on a smaller MCCB to trip on any condition outside of normal operating parameters. Inputs will be CT's and PT's on the genset output bus and utility bus.
- Votlage +/- bias, analog signal, interface with whatever AVR
- Prime mover control, analog signal, interface with whatever governor is supplied
Of course the whole setup will have to be magically approved by the local authority and by the utility, but thats another battle.
Thanks everyone.
RE: synchronize genset with utility - load flow
Good luck! Mike L.