How can gas turbine generators detect load and adjust operating speed accordingly?
The GT generator fundamentally does not “detect” load. Its load is the power that is put into its drive shaft. It simply converts this to electrical power and exports it (minus some small internal loss) to the power grid. End of formal answer to your question! However the power demand on the grid varies all the time as consumers switch on and off. On their own the generators know nothing about this until (with increasing grid load) the grid frequency (50 or 60 Hz) and all the generators on the grid begin to slow down. Frequency or speed is the critical control parameter and not load. Some generating units (or rather their load control systems) will respond to drop in frequency by automatically increasing the power input to their turbines. But in general grid control notices the drop in frequency and more plant is brought on line and loaded up. Daily load patterns are well known and can be prepared for in advance. Some machines are kept at part load (called spinning reserve) and can be
