CN-122021101-A - Method and system for determining equivalent damping ratio of steam turbine base

CN122021101ACN 122021101 ACN122021101 ACN 122021101ACN-122021101-A

Abstract

The invention relates to the technical field of turbine pedestal dynamics calculation, and provides a method and a system for determining an equivalent damping ratio of a turbine pedestal, wherein the method comprises the steps of obtaining the structural size and the material property of the turbine pedestal and establishing a mechanical model of the turbine pedestal; the method comprises the steps of determining a mass matrix and a stiffness matrix of a structure based on a mechanical model to establish a free vibration differential equation composed of a plurality of materials and an equivalent free vibration differential equation of an overall structure, respectively obtaining strain energy of a system composed of a plurality of materials and an equivalent system in each order vibration mode based on the free vibration differential equation composed of a plurality of materials and the equivalent free vibration differential equation of the overall structure according to vibration mode orthogonality, solving to obtain an equivalent complex damping coefficient of each order vibration mode based on the strain energy of the system composed of a plurality of materials and the equivalent system in each order vibration mode, and converting the equivalent complex damping coefficient into an equivalent damping ratio. The equivalent damping ratio of the turbine base can be obtained rapidly and accurately, and powerful support is provided for engineering practice.

Inventors

YANG BIN
HAN YUZHOU
SUN XIAOHONG
XU JUNXIANG
Huang Xidao
LI XU
LI HONGCHAO
Zhu Shezhou
LI LI
WANG YANQIANG

Assignees

山东电力工程咨询院有限公司

Dates

Publication Date: 20260512
Application Date: 20251211

Claims (10)

1. The method for determining the equivalent damping ratio of the steam turbine base is characterized by comprising the following steps of: obtaining the structural size and material properties of a steam turbine base, and establishing a mechanical model of the steam turbine base; based on a mechanical model, determining a mass matrix and a stiffness matrix of the structure to establish a free vibration differential equation composed of a plurality of materials and an equivalent free vibration differential equation of the whole structure; Based on a free vibration differential equation composed of a plurality of materials and an equivalent free vibration differential equation of the whole structure, strain energy of a system composed of a plurality of materials and an equivalent system in each order of vibration mode is respectively obtained according to the orthogonality of vibration modes; based on the strain energy of a system formed by a plurality of materials and an equivalent system in each order of vibration mode, solving to obtain an equivalent complex damping coefficient of each order of vibration mode, and converting the equivalent complex damping coefficient into an equivalent damping ratio.
2. The method for determining the equivalent damping ratio of the steam turbine base according to claim 1, wherein the equivalent damping ratio of each order of vibration mode is obtained by converting the relationship between the viscous damping ratio and the complex damping coefficient based on the equivalent complex damping coefficient of each order of vibration mode.
3. The method of claim 1, wherein the material properties include modulus of elasticity, density, poisson's ratio, and material damping ratio of different materials.
4. The method for determining the equivalent damping ratio of a turbine base according to claim 1, wherein the free vibration differential equation composed of a plurality of materials is: wherein [ M ] is a mass matrix, M is the number of kinds of materials, { ÿ } is an acceleration vector of a structural node, The complex damping coefficient of the ith material is represented, i is an imaginary number unit, [ K ] i is a block stiffness matrix corresponding to the ith material, and { y } is a displacement vector of a structural node.
5. The method for determining the equivalent damping ratio of a turbine base according to claim 1, wherein the equivalent free vibration differential equation of the overall structure is: wherein [ M ] is a mass matrix, { ÿ } is an acceleration vector of a structural node, i is an imaginary unit, and [ K ] is a whole stiffness matrix of the equivalent system, Is an equivalent complex damping coefficient, { y } is a displacement vector of the structural node.
6. The method for determining the equivalent damping ratio of a turbine base according to claim 1, wherein the strain energy of a system composed of a plurality of materials at each stage vibration mode for 1 week: wherein T is the vibration period of the j-th order vibration mode, m is the number of kinds of materials, As a mode-state vector of the model, Is the generalized coordinate of the j-th order vibration mode, And i is an imaginary unit for the damping coefficient of the j-th order vibration mode corresponding to the first material, and [ K ] l is a block stiffness matrix corresponding to the first material.
7. The method for determining the equivalent damping ratio of a steam turbine base according to claim 1, wherein strain energy of an equivalent system at 1 week of each order of vibration mode is: wherein T is the vibration period of the j-th order vibration mode, m is the number of kinds of materials, As a mode-state vector of the model, I is an imaginary number unit, and [ K ] is an overall rigidity matrix of the equivalent system, Is the j-th order vibration mode complex damping coefficient of equivalent damping.
8. A turbine base equivalent damping ratio determination system, comprising: the model building module is configured to acquire the structural size and the material property of the steam turbine base and build a mechanical model of the steam turbine base; a differential equation establishing module configured to determine a mass matrix and a stiffness matrix of the structure based on the mechanical model to establish a free vibration differential equation composed of a plurality of materials and an equivalent free vibration differential equation of the overall structure; the strain energy calculation module is configured to respectively obtain strain energy of a system consisting of a plurality of materials and an equivalent system in each order of vibration mode according to the orthogonality of the vibration modes based on a free vibration differential equation consisting of the plurality of materials and an equivalent free vibration differential equation of the whole structure; The damping ratio determining module is configured to obtain an equivalent complex damping coefficient of each order vibration mode based on strain energy of a system composed of a plurality of materials and an equivalent system in each order vibration mode, and convert the equivalent complex damping coefficient into an equivalent damping ratio.
9. A computer readable storage medium having stored thereon a computer program, which when executed by a processor, implements the steps of a method for determining a turbine foundation equivalent damping ratio according to any one of claims 1-7.
10. A computer device comprising a computer readable storage medium, a processor and a computer program stored on the computer readable storage medium and executable on the processor, wherein the processor, when executing the program, performs the steps of a method for determining the equivalent damping ratio of a steam turbine foundation according to any one of claims 1-7.

Description

Method and system for determining equivalent damping ratio of steam turbine base Technical Field The invention belongs to the technical field of turbine base dynamics calculation, and particularly relates to a turbine base equivalent damping ratio determining method and system. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. The steam turbine base is used as an important structure for supporting the steam turbine unit, and the dynamic performance of the steam turbine base directly influences the safe and stable operation of the unit. The damping ratio is an important parameter for describing the energy dissipation capacity of the structure in the vibration process, and has important significance for accurately calculating the vibration response and the dynamic stability of the turbine base. However, the turbine base is usually a combined structure composed of steel, concrete, piles and soil, the damping performance of different materials is greatly different, and the damping ratio of the whole structure cannot be simply taken as that of a certain material. Thus, there is a need for an accurate and reliable method of determining the equivalent damping ratio of a turbine base. At present, although some researches on a method for calculating the damping ratio of a combined structure exist, most of the methods are aimed at specific structural forms or material combinations and lack of universality, and meanwhile, the existing methods also rarely consider the specific combined structure of steel, concrete, piles and soil of a turbine base. Disclosure of Invention In order to solve the technical problems in the background art, the invention provides a method and a system for determining the equivalent damping ratio of a steam turbine base, which are combined with a material damping ratio, a complex damping theory and a modal strain energy model, fully consider the characteristics of a combined structure of the steam turbine base, which is formed by steel, concrete, piles and soil, can more accurately reflect the actual damping performance of the structure, can quickly and accurately obtain the equivalent damping ratio of the steam turbine base, and provide powerful support for engineering practice. In order to achieve the above purpose, the present invention adopts the following technical scheme: a first aspect of the present invention provides a turbine base equivalent damping ratio determining method, comprising: obtaining the structural size and material properties of a steam turbine base, and establishing a mechanical model of the steam turbine base; based on a mechanical model, determining a mass matrix and a stiffness matrix of the structure to establish a free vibration differential equation composed of a plurality of materials and an equivalent free vibration differential equation of the whole structure; Based on a free vibration differential equation composed of a plurality of materials and an equivalent free vibration differential equation of the whole structure, strain energy of a system composed of a plurality of materials and an equivalent system in each order of vibration mode is respectively obtained according to the orthogonality of vibration modes; based on the strain energy of a system formed by a plurality of materials and an equivalent system in each order of vibration mode, solving to obtain an equivalent complex damping coefficient of each order of vibration mode, and converting the equivalent complex damping coefficient into an equivalent damping ratio. Further, based on the equivalent complex damping coefficient of each order of vibration mode, the equivalent damping ratio of each order of vibration mode is obtained through conversion by combining the relation between the viscous damping ratio and the complex damping coefficient. Further, the material properties include modulus of elasticity, density, poisson's ratio, and material damping ratio of the different materials. Further, the free vibration differential equation composed of a plurality of materials is: wherein [ M ] is a mass matrix, M is the number of kinds of materials, { ÿ } is an acceleration vector of a structural node, The complex damping coefficient of the ith material is represented, i is an imaginary number unit, [ K ] i is a block stiffness matrix corresponding to the ith material, and { y } is a displacement vector of a structural node. Further, the equivalent free vibration differential equation of the integral structure is: wherein [ M ] is a mass matrix, { ÿ } is an acceleration vector of a structural node, i is an imaginary unit, and [ K ] is a whole stiffness matrix of the equivalent system, Is an equivalent complex damping coefficient, { y } is a displacement vector of the structural node. Further, the strain energy of a system composed of a plurality of materials at each order of vibration mode vibratio