Analysis of the Sliding Pressure Operation for Throttle Controlled Steam Turbine Generation Unit

Sliding pressure operation for the throttle controlled power generation units was rarely studied in the past, because there is no valve points to set like the nozzle controlled generation units. In this paper, the calculation of the sliding pressure operation for throttle controlled generation units was described, and GateCycle™ physically based computer model for steam turbines and feedwater pumps set was provided. A sliding pressure operation calculation example for an existing 600MW unit was given in detail. It is concluded that controlling of the steam turbine main control valve pressure difference is the key for throttle controlled generation units. It´s the best practice for power plant owners that maintaining a minimum pressure difference for the main control valve while satisfying the AGC control response requirements.