I am studying ALFC and I have a few questions about it. Consider the flyball governor in this system. It senses the changes in speed of the turbine. If load is increased, the balls will slow down and will move inwards, moving point B upwards. Now, this will open some additional valves to allow more fuel. What is the role of speed changer in this? Basically, what is a speed changer? How is reference power set in the speed changer? Please explain. Also, is it correct that the primary ALFC loop (containing governor) is used to prevent sudden changes in frequency and there remains some steady state error in frequency even after opening or closing the additional valves? Thanks in advanve!