Research And Analysis On Parameter Identification And Power System Stability Of Steam Turbine Governing System

With the continuous improvement of power system control and increased user requirements for power quality,power system stability and power supply quality become the research subject of power grid.Steam turbines are important power machinery equipment in thermal power plants,drive generators to produce electricity.The valve flow characteristics of steam turbine is an important factor affecting the stability of power systems,the operating characteristics of the steam turbine governing system have a significant impact on the dynamic stability and long-term stability of the power system.Therefore,valve flow characteristics,parameter identification and simulation check of steam turbine governing system research was carried out,it is of a great significance to maintain frequency stability and improve power grid stability.In this paper,the valve flow characteristics,the parameters identification and simulation check were aimed at steam turbine governing system.First,the valve management of steam turbine that is valve opening process were modeled and analyzed.Secondly,the field test,data processing,selection of identification algorithms,and introduction of identification software were in-depth analysis and researched before identification of the pure condensing condition on steam turbine generator unit,it also points out the problems that need attention in the parameter identification process.Based on the above analysis and research,for the valve flow characteristics of steam turbine,valve management model and machine-network coupling model for steam turbine were established in Matlab/Simulink.The different local flow characteristic coefficients of the steam turbine governing valve of the valve flow characteristics curve were analyzed in the nonlinear region,the change of power curve after the given amplitude disturbance were obtained in the steam turbine governing valve.For the parameter identification of steam turbine governing system,the parameter identification software was developed based on Visual C++ and the improved steam turbine power model was established in Matlab/Simulink.The improved steam turbine power model with the actual power curve fitting condition was compared,and using the improved universal power model of the steam turbine to simulate and verify the power response curves of different loads under valve control mode.The results show that when the valve is working in the nonlinear region,steam turbine generator unit power curve varies with local flow characteristics coefficient.When the local flow characteristics coefficient deviates from the ideal flow characteristics coefficient,the power fluctuation curve amplitude and the number of oscillations correspondingly increase.The larger or smaller local flow characteristics coefficient exerts a detrimental influence on the rapid stability of power response under the primary frequency control.To solve this problem,the governing stage pressure control loop was designed and put,which can overcome the nonlinear relationship between the governing valve opening degree of the steam turbine and the inlet flow,effectively suppress power fluctuation and improve power grid stability.The parameter results from the identification software was input into the improved universal power model of the steam turbine,compared with the typical steam turbine power model,the model considers the influence of the load fluctuation region and main steam pressure on the overall verification of the steam turbine model during the power curve response process,the model simulation curve fits the actual power response curve better.Finally,the test simulation and actual test verification under the valve control mode of the actual unit are within the range of the error index,it further illustrates that the improved steam turbine power model is universal and better reflect the load adaptability of actual unit,a reference for power grid stability analysis and calculation was provided.