I have an example about droop and it asks to calculate final frequency in a grid after one generator power generation is lost. The answer is given as 59.889 Hz; however, I am calculating as 59.99 Hz. What am I missing?
The question is
Assume a grid has lost one generator (42MW) and the remaining
generation is 1132 MW. All generators have governors set to 5% droop.
What is the final frequency?
This is the given formula
$$ \Delta(f) = \frac{R.\Delta P_{gen,MW}}{\sum S_{online, MVA}}. $$
$$ \Delta(f) = \frac{0.05 x 42}{1132}=0.0019. $$$$ \Delta(f) = \frac{0.05 \times 42}{1132}=0.0019. $$ Final frequency is 60-0.0019=59.9981