What is the normal governor droop percentage?

The normal governor droop percentage, which is widely utilized in power systems, is typically around 5%. This droop percentage represents the relationship between a change in rotor speed and the change in active power output of a generating unit. Specifically, a governor droop of 5% means that for every 5% decrease in system frequency, the generator will increase its output by 100% of its full load. This characteristic is crucial for maintaining frequency stability and ensuring an appropriate response from generators to changes in load.

Governors with 5% droop are common because they strike a balance between responsiveness and stability, allowing generators to adjust their output without causing significant fluctuations in system frequency. In contrast, other values like 2%, 7%, or 10% can lead to either overly sensitive responses or inadequate power adjustment, leading to potential frequency instability in the grid. Thus, the choice of 5% as the normal droop percentage is a standard practice in power system operations, aligning with reliability and efficiency goals.