In order to obtain the sliding pressures of steam turbine with extraction for heating

the matrix equation for steam and water in regenerative system was employed to analyze the characteristics of thermal power system under conditions with varying extraction flow

electrical loads and backpressures. On the basis of the unit's performance test data under pure condensing conditions

steam turbine valve discharge characteristics and output correction curves of backpressure

the optimization calculation method for the sliding pressure during heat supply period was put forward. Moreover

by taking a 350 MW unit as the example

this calculation method was applied to carry out varying load calculation on the basis of the rated-sliding pressure curves and test data

and the sliding pressures of this unit under conditions with different electricity loads

backpressures and extraction flows were obtained. The results show that

the proposed method is simple and effective

which has better practical engineering application and promotion value.