Changing Dial Type Governor UG-40 from 4% Drop to Zero Droop


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What will be the response of the governor if the initial setting of the droop is 4 %. After the unit will synchronize and pick load by increase engine raise power up to its 85% capacity (e.q 9 MW). If I will change the droop setting put into Zero. What will the happened to the carried load?

Droop speed control defines how much load the unit will change for a given change in the error between the prime mover speed reference and it's actual speed. A machine with 4% Droop will change it's load by approximately 25% of prime mover rating for each 1% change in speed error. If the unit is synchronized to a grid with other machines and the grid frequency is stable, then as the operator changes the prime mover speed reference by 1% the unit load will change by approximately 25% of prime mover rating.

The presumption is that grid frequency is stable, as it should be on a well-regulated grid. If the grid frequency changes when the unit is operating at a steady-state output, then the speed error will change and that will cause a change in unit output. For example, of the prime mover speed reference is 103.0% and the grid frequency is 100.0%, the unit output will be approximately 75% of the prime mover's rating (it the prime mover were rated for 4.0 MW, the output would be approximately 3.0 MW). If the grid frequency increased by 0.5% while the prime mover speed reference remained at 103.0%, the speed error would decrease to 2.5%, and the unit load would decrease to 62.5% of prime mover rating (2.5 MW in this example). (It should be noted that some governors use positive droop, and others use negative droop. And, that's all manufacturer-specific--even the positive and negative terminology. So, it depends on your machine's governor.)

Now, as for what will happen if you change the "Dial Governor" (I'm not familiar with a Dial Governor, and presume it's just a dial used to set the Droop regulation/percentage)--that is difficult to say. In my estimation, changing the Droop from 4% to 0% is equivalent to telling the governor to be in Isoch speed control, and if the unit is synchronized to a grid with other machines then the unit output would likely be very unstable. Droop speed control mode is the governor mode that allows multiple units to be synchronized together (operate in parallel with each other) without fighting each other to maintain frequency of the grid. Changing the Droop regulation to something approaching 0% while operating is going to drastically affect the stability of the machine--in my estimation, not knowing anything about "Dial Governors".

Wish I could be more specific, but hope this helps!