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First of all, I need a clarification about droop characteristic. To my knowledge, droop can be seen as a speed error or mismatch of turbine speed in case of load change. In other words, it is said that droop of governing system is let's say 5% if change of 100% of load is causing 5% of change of turbine speed. Droop can be understood by characteristic frequency-output power and is approximately linear.

Now, I have found one example. It says basically this: "When frequency changes in the grid, every turbo-generator unit reacts and adjust its generated power. For instance, when frequency falls by about 0.1%, generation of a unit should be increased by 20% with droop of 5%."

Now I cannot understand this example. How 20% of more generation with 5 % droop can correct 0.1% in frequency drop? I guess this example assumes that there is only one unit in the grid which is allowed to correct frequency error.

What if there are more units on the grid? Due to primary regulation every turbine controller system (governing system) will try to correct this.

Thanks