Turbine Governor Control

Governor control at each unit of generator can be function as speed / velocity controller.

The concept of speed control can describe picture as follow that pulling reaction between mechanic torque and electric torque created the balance.




While the sytem get change of load, that changes called change of output electric torque to generator. Diffrerential between mechanic torque and electric torque created speed change, the fraquency also change.
















































In the case of motor load likes pump or fan, electric power is very depending on frequency. So variable of frequency is depending on load accumulation with damping constant in % as change as load.
The damping constant has value between 1 to 2, for example if we have damping constant 2 it is mean frequency change 1% can created load change 2%.

Case:
The system consist 4 unit generator which capacity 500MVA total supplying 1200MW and frequency 50Hz. Inertia constant for each unit is 5s base on 500MVA. Variation load 1,4% for 1% frequency change or damping constant 1.4.
While the load suddenly decrease 50MW, how much change of frequency?

Find the solution on next post:
http://idpowerstation.blogspot.com/2011/05/load-change-on-free-governor.html