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Change in Excitation at Base Load
What will happen if I change the base load of our GE frame 5 machines with Mark V control. They are not connected to the grid.
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we have GE frame 5 machines with Mark V control.

while running in parallel operation (not with grid), if I put one machine at base load & change it's (base load machine) power factor towards unity will MW output increase for base load machine?

sarfareumesh@gmail.com

1 out of 1 members thought this post was helpful...

sarfareumesh,

>while running in parallel operation (not with grid), if I
>put one machine at base load & change it's (base load
>machine) power factor towards unity will MW output increase
>for base load machine?

We don't know anything about the nature of the load (lights, motors, transformers, etc.) the gas turbine/generators are driving. I also strongly suspect there is some kind of "power management system" or frequency control system that is sending signals to one or both of the Mark Vs to control FREQUENCY--not load, frequency.

I don't really understand the question, though. Are you asking if there is something that can be done to increase the MW being produced by a gas turbine/generator that is already at Base Load? The definition of Base Load is when the IGVs are at maximum operating angle AND the fuel is being controlled/limited by CPD- or CPR-biased exhaust temperature control. This mode of fuel control is putting the maximum amount of fuel into the turbine to keep the actual exhaust temperature equal to the exhaust temperature reference. If any more fuel is admitted to the turbine it will be "over firing" which means the internal components are being exposed to temperatures higher than can be tolerated while still providing optimal parts life for long-term operation.

And fuel equals real power: generator stator current, watts, MW, load--more fuel equals more load; less fuel equals less load.

Excitation equals reactive power: reactive current, VArs, power factor. Excitation also equals generator terminal voltage.

An islanded, or captive, power plant can only supply the power required by the load--which is the aggregate total of all the lights and motors and televisions and tea kettles and transformers and computers and computer monitors and arc furnaces or whatever is at your facility) at the power factor which is the aggregate power factor of all the lights and motors and televisions and tea kettles and transformers and computers and computer monitors and arc furnaces or whatever is at your facility.

If you, or the power management control system, try to make more power (MW) than the load of the facility requires the result will be that the frequency of the facility will increase. If you or the power management control system tries to make less power (MW) than the load of the facility requires the result will be that the frequency of the facility will decrease.

If you try to make more or less VArs than the facility requires the result will be that the voltage of the facility will be higher or lower than the desired facility voltage.

If you're not familiar with the concept of the "power triangle" you should use your preferred World Wide Web search engine to study the concept. Changing excitation can have some effect on real power (MW), but not too much at higher loads, including Base Load.

I suspect if you manually change excitation on either unit the excitation of the other unit will "respond" in some fashion to try to maintain voltage or VArs or power factor--if not the AVR (the exciter regulator) then by the power management system (because it's also probably controlling--to some extent--facility voltage as well as frequency).

The real power (MW) produced by a gas turbine/generator is a function of fuel flow. The VArs/power factor (reactive power). There is a small relationship between real power and reactive power, but is usually of no use in a power plant (there are exceptions, and they are extremely unusual and complicated--and probably do not apply to your facility).

For all intents and purposes, one cannot change real power (MW) by changing excitation--one changes real power by changing the fuel flow to the gas turbine of a gas turbine/generator. And if the unit is operating at Base Load when fuel flow is already at the maximum limit there is no more real power available from the gas turbine. And the generator is just a device for converting torque from its prime mover into stator amperes at a relatively constant terminal voltage. Real power is generator terminal voltage (which is pretty constant, or should be for most sites) multiplied by generator stator current multiplied by the power factor of the load, which shouldn't vary too much.

I hope I have answered your question. Without knowing a LOT MORE about your facility and its configuration and its load it is extremely difficult to say any more. But, if you are asking if by changing excitation if it's possible to increase the power being produced by a gas turbine/generator that is already operating at Base Load (which is the maximum power output possible for the present ambient and machine conditions), the answer is, for all intents and purposes: no.

There may be some unique aspect of your facility we are not aware of, but I suspect not.

Load is controlled by controlling fuel flow, and VArs/power factor is controlled by changing excitation. There is a small relationship, which is even smaller at Base Load), so there is little appreciable change to the gained by changing the excitation at Base Load--for the majority of gas turbine/generators and power plants, islanded/captive or synchronized to a grid.