Fast Valving with Reheat and Straight Condensing Steam Turbines

Fast valving of steam turbine-generators is a method of rapidly reducing the mechanical power output to assist in preventing instability (loss of synchronism) of the steam turbine-generator with the rest of the power system. Although rarely used, fast valving can be a very effective stability aid [l]. Many operating turbines made by the authors' company have fast valving capabilities. This paper describes the current fast valving capabilities of these turbines, both reheat types and straight condensing types, and illustrates some of the benefits for system stability that can be obtained with these capabilities. Planning considerations for fast valving are also discussed, including some advanced fast valving concepts.