Thermal Power Unit Operation Flexibility Analysis And Control Strategies Optimizaion

With the continuous development of power system,large-capacity and high-parameters coal-fired thermal power unit(TPU)has become the main force of power supply and will continue to hold the role in power grid for a long time.The continuous increase in the proportion of power generated by new energy generators has made these large TPUs,which are based on energy saving and high efficiency,to undertake the tasks of in-depth frequency and peak-load regulation(FPR).In order to seek efficient control strategies and operating modes,the potential of FPR of these THUs are analyzed through theory and large amounts of field tests.And based on the analyzed results,the flexible operating modes of TPUs and control strategies for in-depth FPR are proposed.The proposed models and control strategies can be used to deeply research the dynamic characteristics of the TPUs to find an efficient way to meet the growing demand for absorption of new energy generators in power grid.The main contents and results are as follows:(1)Taking the several typical TPUs as the objects,the mathematical models are constructed by theoretical analysis and field tests,which can reflect the dynamic and static characteristics accurately and provide conditions for the analysis of safety and efficiency s of THU's FPR consequently.The mathematical model of the whole system covering each part,which based on the unit's equipment and thermodynamic law,is constructed.Improved gravitational algorithm(IGSA)is introduced to identify the model by large amounts of data of field tests accurately.Based on the mathematical model and combined with test research of boiler heat storage capacity(BHSC),the capacity of FPR of TPU is analysed and the safety boundary and efficiency change characteristics of the different TPUs are obtained,which are verified by comparing with the data of field tests of several TPUs.(2)To solve the problems that traditional control strategies are difficult to adapt to the regional grid operation mode,the flexible operation mode and control strategies are proposed,which can obtain the capacity of TPU's FPR combining with the characteristics of the unit,especially its steam turbine.With the variety of power grid structure and the change of TPU's role in the regional power grid,the traditional operation mode of TPUs and its test control strategies can easily lead to problems such as power oscillation and boiler explosion.In order to ensure the safety of TPU and power grid,new control strategies are put forward combining with the characteristics of THU such as capacity and its BHSC and considering the structure of the regional power grid and the load interval of FPR of TPU.The field test data show that the control strategies can improve the rate and amplitude of FPR of TPU and TPU's efficiency effectively.(3)By comparative analysis of BHSC and the capacity of FPR of different TPUs,the characteristics of these TPUs affecting the absorption of new energy generators are obtained and control strategies based on characteristics of boilers are put forward,which are effective analysis means for the comprehensive power dispatching and the rational distribution of the power supply points.Combined with the statistical data of boiler explosion and its detonator parts,load variation characteristics of several typical units are analyzed by simulation and field tests and the influence mechanisms of boiler type,combustion mode and structure of steam water system on the FPR performance of TPU's are presented.Based on these conclusions,control strategies are provided for improve the capacity of FPR on the basis of TPUs safety,whose effectiveness are verified by practical application.(4)The influence of the increasing power transmission cross regions on the FPR of power grid is analyzed,and operation control strategies of TPU in the regional and the isolated power grid are proposed.Based on the typical regional and multiple isolated power grids,the load disturbance of the user side and action influence of other power supply points on TPU in power grid are studied by dynamic simulation.Combining with the typical fault data of TPUs,operation characteristics of TPU and the coupling law of TPU and power grid are obtained.Based on the dynamic mathematical model verified by field tests and its dynamic characteristics,cotrol strategies and operation mode of TPU in the regional and isolated power grid are put forward,which provide the technology support for TPU in regional and isolated power grid.