Prime mover speed governors

OPERATORS OF power generating equipment realize that it is desirable from a system control point of view to have all speed governors on their interconnected systems with reasonably similar steady-state characteristics. Normal load changes then would be shared by all units in proportion to their ratings and the action of supplementary controllers would be uniform. This would result in smaller deviation of frequency and load distribution from the desired values. Most attempts to make all prime movers on a system respond to system changes in proportion to their ratings have been confined to setting all speed governors so that they have equal steady-state speed regulation. Tests show that the response of prime movers to changes in system frequency or to the action of supplementary controllers is of a random nature and has little relation to machine rating or steady-state speed regulation. This article outlines the factors that contribute to the random nature of prime mover response and indicate how testing programs for existing units, as well as future design changes of governing systems, can produce a major improvement.