Dear sir.

we have 1.6 megawatt diesel generator which we connected with live bus bar 13.8kv. when we synchronize the unit and start the to loading, suddenly all the load transferred to the diesel generator more than the capacity.

please tell me what is the problem. and what is the cause we are using 2301A governor controller.

johnregal1107 [at] yahoo.com

 

Sort of by definition, a "black start" diesel generator is not connected to any grid or synchronized with other power generating units when it's started or running because it's supplying electrical power under emergency conditions to a load (building or site) that has been isolated/disconnected from a larger grid or other source of AC power.

And, because it's not connected to any grid and it is a "black start" generator, the governor of the prime mover (the diesel in your case) is usually configured to operate in Isochronous speed control mode in order to provide a constant frequency output as long as the load is less than the rated output of the prime mover.

So, it seems something has changed at your location. Is the "black start" unit now to be used to provide power to a larger grid? If so, it's governor should probably be switched to Droop speed control mode before syncyhronizing or at the instant of synchronization.

If you are not switching the governor to Droop speed control mode when you are synchronizing to a grid (which, again, is not the typical definition of a "black start" machine) then the Isochronous governor will try to "take" all the load it can, possibly overloading the prime mover.

When power generating units are synchronized (paralleled) with other generating units, they are usually only operated in Droop speed control mode. If the governor is in Isochronous speed control mode when you are synchronized to a grid with other generating units and you try to "increase" load, you are really trying to increase the frequency of the output, which would have the effect of "grabbing" load and probably overloading the prime mover.

I'm not familiar with the 2301A governor, but if it's a Woodward Governor Control unit the instructions are probably not too bad, but probably not that great, either. Read the fine manual and assess how the generator is to be configured for the two types of operation: independent (isolated) from any other electrical generating units or a grid, and in parallel with a grid or other electrical generating power units.

If you're just operating the "black start" unit for testing purposes by synchronizing to a grid to accept some load, it must still be switched to Droop speed control mode to control the load to be accepted by the unit, and then switched back to Isochronous speed control mode once separated from the grid and placed back in emergency "black start" readiness condition.

 

can i change From Droop To isochronous during Generator loaded or reversal position.

isochronous Mode can i put Preselected Load or not accepted this mode.

 

Well, you might be able to change from Droop to Isochronous during loaded operation in parallel with a grid, but you'll likely only do it once. The unit will most probably go unstable and then trip.

And, no; Isochronous mode does not allow load setpoints. The whole purpose of Isochronous mode is vary power to maintain frequency regardless of load changes. So, the unit needs to be able to respond to changes in load that would tend to change the frequency and setting a load setpoint to be controlled to would result in an unstable frequency, and likely a unit trip.

A lot has been written about frequency control and Droop and Isochronous modes on control.com. It's like riding a bicycle and trying to maintain a constant speed with a changing load (or changing terrain). Use the 'Search' feature (in the corner of the Menu bar at the top of every control.com page) to see some of the past threads.