Operation And Allocation Optimization Based On System Modeling Of Supercritical Thermal Power Unit

Greenhouse gas emissions of fossil fuels power generation have posed a great threat to the global environment. Wind power, photovoltaic and other renewable energy power generation technologies have become a trend to meet the requirement of sustainable development. The variability of wind power and photovoltaic adds, however, the uncertainties. Meanwhile, the increased nonlinear power load and the large difference between the peak load and off-peak load further exacerbate the fluctuation of the power system. To maintain grid stability, the large-scale thermal power units with wider range load and strong peaking capacity are imperative to participate in power peaking. The variable load operation becomes inevitably more frequent. On the one hand, given the grid load variations and the health of thermal power plant equipment, the considerable energy saving potentials are analyzed in detail and full variable load optimization methods are proposed in the present work. On the other hand, the prospective studies of steam turbine system configuration optimization problems, and the improved economic performances of the steam turbines in low load operation have significant theoretical and practical values.Building on the concepts and characteristics of the steam distribution modes and the operation modes, the differences of typical parameters, including the pressure loss of regulating valve and the efficiencies of the unit, feed water pumps and operation cycles, are analyzed in different operation modes. The optimization direction is, therefore, clarified in this work. The variable operating characteristics of the steam turbine system are investigated. Several theoretical models for the components, such as the control valves, the steam turbine flow through the body, the reheating system, the feed water pump along with feed water turbine and the condenser, are proposed based on the modularization. The mathematic functions of the thermal system are given using the matrix.By studying the 660MW Supercritical Turbine Units, this paper makes mathematical model of optimal operation on account of feasible interval for main steam pressure based on current thermal performance indicators of turbine unit. Through numerical simulation, the validity of model is verified and optimization strategy is presented. Firstly, the turbine unit operates along sliding pressure curve on three-value point at medium-to-high load and on two-value point at lower load. Secondly, it can adopt'loop adjustment'method based on load dispatch instruction or assign different loads to two turbine units reasonably in order to avoid running among high heat-rate area.Based on the theory of economical operation, this paper points out that strengthening cycle thermal efficiency and increasing relative internal efficiency for turbine are two cores. Taking cycle thermal efficiency as center, this paper suggests adding super-high pressure heater and the results show that this transformation can decrease turbine specific heat rate. When taking relative internal efficiency as lifting goal, this paper puts forward idea about LP cylinder with mixed sizes. The economic performance can be raised by switching cylinder in the light of different load.