Application research and optimization of back pressure extraction steam turbine controlled by converter

Abstract

The application of the first converter controlled BEST （back pressure extraction steam turbine） in the ultra-supercritical secondary reheat unit is studied as the object. The control operation mode of the BEST is described， and the problems in the commissioning process of the BEST， such as the overload in converter control mode， the great fluctuation of feed water flow produced by the load dump of BEST， and the trip of BEST controlled from MEH （micro electro-hydraulic control system） mode to converter mode， are analyzed. By the adjustment of operation parameters and control modes， such as improving the back pressure of BEST， retarding the regulating valve movement range of BEST and increasing the acquisition time of speed signal and so on， finally the problems are effectively solved， making the BEST into energy-efficient regulating valve full control mode. Afterwards， in the process of turbine changing to load， feed water flow and extraction system and small generation power are properly matching， which can provide reference for similar new units.

Keywords

• back pressure extraction steam turbine
• converter
• small generator
• overload
• load dump