Mathematical model of flow characteristics of steam turbine plant

Abstract

A large number of generating equipment installed at thermal power plants (TPPs) operate at the limit of their fleet life resource or beyond it. Malfunctions and defects occur during the entire period of operation of steam turbine plant (STP) of TPPs. It causes performance degradation of efficiency, reliability, and maneuverability of STP. Thus, the methods to provide monitoring over the technical position of the elements and/or functional units of steam turbine plant are to be applied. Hence, special attention is to be paid to the development of methods to monitor the technical position and diagnostics of generating equipment of TPPs. The methods are based on a mathematical model of flow characteristics of steam turbine plants. It allows us to consider the effect of changes in the open flow area of the individual compartments of a steam turbine on the pressure distribution over the flow path. To develop the model, the authors have applied mathematical modeling methods and the balance relations of mass and energy methods. The solution of the equations of the obtained linear and nonlinear systems is carried out by methods of computational mathematics. Calculation of thermodynamic parameters of the coolant is carried out based on tables of properties of water and water vapor and software for their description. A mathematical model of a steam turbine plant has been developed. It represents a set of linear and nonlinear algebraic equations that consider the flow discharge characteristics of the steam turbine compartments. Also, it makes possible to assess the technical position and it considers the effect of defects on the pressure distribution over the flow path of the steam turbine. The results of the statistical analysis prove that the model has been recognized adequate under the variation range in the electrical load. The results of the development of mathematical steam turbine plant model can be used to develop intelligent systems to monitor and diagnose power generating equipment of TPPs. Application of these systems allow the management of the TPP to change over from the system of preventive maintenance of equipment to the system of the repair of equipment according to technical position.