Research On The Optimal Strategy Of High Control Valves For 600MW Steam Turbine Under Deep Variable Conditions

With the increase in electricity consumption in my country,renewable energy sources such as wind power and solar power have developed vigorously.However,wind power and photovoltaic power generation have certain intermittent and instability.In order to absorb renewable energy power generation,thermal power plants are often under variable operating conditions or even deep variable operating conditions.Some new problems have also appeared in this kind of operation: some units have undergone long-term operation,and after the modification of the flow part,wear or DEH modification,the actual flow characteristics of the steam turbine regulating valve deviate from the design value,which causes the unit to control Problems such as reduced capacity and insufficient primary frequency regulation;while the steam quality at the regulating stage is high,and the opening sequence of different regulating valves under different steam distribution modes also has a certain influence on the efficiency of the unit;the sliding pressure curve specified by the original factory only considers the unit load when designing A series of problems such as the influence of a single factor and the relatively high energy consumption of power generation.This paper takes a 600 MW supercritical unit as the research object,and optimizes the unit through the following aspects:(1)A method for identifying steam turbine flow characteristics based on the LSSVM model is proposed,and a data mining model reflecting the mapping relationship between the unit load,main steam pressure,main steam temperature and other key operating parameters of the unit and the actual steam flow of the steam turbine is established.The results of the research found that the use of the LSSVM model to predict the main steam flow has the characteristics of high accuracy,strong generalization ability,and short running time.Through data mining,the flow characteristics of the steam turbine can be obtained,which can effectively improve the control ability and operational stability of the unit.(2)Through the establishment of the overall research model of the steam turbine control valve and the control stage,according to the Fryger formula,the key theory of the calculation of variable conditions is studied.Use C++ language programming through vc6.0 platform to realize this calculation process.Through program calculation,it is found that the error between the calculated temperature and the actual measured value after the adjustment stage is basically less than 2%,which meets the needs of the project.(3)Calculate the different steam distribution modes of the unit through the program,and obtain the flow characteristic curves under different steam distribution modes;compare the efficiency of the regulating stage under different steam distribution modes through the calculation results;and excite vibration under different steam distribution modes It is necessary to conduct theoretical research;comprehensively considering the economy and safety of the unit,it is recommended that the unit adopts a diagonal opening steam distribution method.(4)On this basis,the unit is modeled by EBSILON software,and then the optimal initial pressure of the unit under different circulating water inlet temperatures is determined by the software.