Dynamic Characteristics Analysis And Optimization Of Turbine Generator Spring Foundation

Compared with abnormal rigid foundation,spring foundation has good damping effect,can do unit alignment and adjustment without stopping,and can also solve the problem of uneven settlement of foundation.Thus,it is used by more and more power stations,and it can become the trend of the future development of China's Turbine Generator Foundation.As an important part of power station,the turbine generator foundation carries the core equipment of the whole power station---Turbine generator set.The dynamic characteristics of turbine generator foundation directly affect the safe operation of the whole station.However,because the spring foundation has a huge volume?complex structure and expensive cost,when do the design of the spring foundation of large turbine generator needs to consider the double indexes of the dynamic characteristics and the quality.So the goal of improving the operation safety of turbine generator foundation and reducing the construction cost can be reached.In this thesis,the dynamic characteristics of the spring foundation of turbine generator are analyzed,and the structural size is also optimized.The optimized design of the maximum vibration line displacement,the maximum static stress and the total weight of the foundation,these performance and quality indexes were realized.Mainly completed the following work:Firstly,according to the analysis of the dynamic characteristics of spring foundation of the turbine generator,there are many problems,such as difficulty in modeling,large amount of calculation and long time consuming.In this paper,the calculation of the dynamic characteristics of spring foundation of the turbine generator is simplified from two aspects:the structure loads simplified and the change of the disturbing force.In the simplification of structure and loading boundary conditions,the top plate is simplified into a space bar structure composed of transverse beams,and the set weight is simplified using the lumped mass method and loaded into the corresponding position on the foundation.Then,the bottom of the foundation column is set to all constraints.On the change of disturbing force,when is in the analysis of foundation dynamic characteristics,the old disturbing force loading way that only one disturbing force is applied to the calculation of the dynamic characteristics is changed to all forces applied at the same time.At last,in order to verify the feasibility of the simplified method and the disturbing force change,we do some compared analysis as following: the simplified model were compared in constant method and variable force method,the solid model and the simplified model used the modal superposition method,the simplifiedmodel used two different disturbing force mode and the simplified model are analyzed in two kinds of dynamic characteristics analysis method of the modal superposition method and full method.The results show that: The result of the analysis of the dynamic characteristics of the foundation are not affected by applying a constant force or variable force;considering the safety and efficiency of the design results,the beam element model can be used to analyze the dynamic characteristics of the foundation,at the same time,the force can be applied in all the same time;the full method can be used to analyze the maximum vibration line displacement in the whole frequency range and the modal superposition method can be used to analyze the maximum vibration line displacement of the unit during start-up.Secondly,aiming at the problem that the optimal design of the spring foundation of turbine generator is complex,the design variables and the optimization target can not be expressed explicitly,Kriging surrogate model optimization algorithm is used into the optimal design of spring foundation for s turbine generator in order to realize the optimal design of the spring foundation.When designing the samples,in order to avoid repeated sampling points in the small area and make the sample points representative,LHS is used to extract the sample points in the design interval,so that the sample points in the design interval can be uniform distribution.Finally,in order to balance local and global search,in this paper,EI is added to the optimization process to find the global optimal solution.Finally,the optimal design of the spring foundation of the turbine generator is realized.The results show that: after the optimum design of the column and the cross section of the rod as the design variables and the maximum vibration line displacement as the optimization objective,the maximum dynamic displacement decreased by 17.16% and 35.33% respectively,the dynamic performance of foundation is improved.After the optimization design of the foundation weight as the optimization objective,the section size of the member is taken as the design variable;foundation weight is decreased by 12.8%,which is reduced significantly.Thirdly,aiming at the problem of multi-targets,multi-constraints and multi-variables in the optimal design of the spring foundation of turbine generator,Kriging surrogate model optimization algorithm is used in multi objectives optimization design for improving the dynamic performance and reducing the foundation weight.Hierarchical optimization method is used to solve the problem that the design variables are not uniform in the multi-objective optimization design.The multi objectives optimization design of the foundation is transformed into a single objective optimization design by weighting coefficients.The results show that: after optimization,the maximum vibration line displacement and foundation weight decreased by 38.7% and 4.8% respectively,the dynamic performance of the foundation and the economic benefits are obviously improved.Optimization results show that: the optimization method used in this paper can be applied to the optimal design of the spring foundation of turbine generator.After optimization,the dynamic performance of the foundation has been significantly improved,and the weight of the foundation has been significantly reduced.The result of the optimization design and the optimal method can provide reference for the structural design of the turbine generator foundation.