Method for building and simulating large marine steam turbine

Abstract

The invention discloses a large marine steam turbine building simulation method, which comprises the following steps of: 1, decomposing a steam turbine set model into a plurality of basic models according to a topological structure and physical characteristics of a steam turbine; 2, aiming at the physical models corresponding to the basic models, adopting a statement modeling method, and converting the physical models into mathematical models in an equation expression form; and step 3, orderly combining and connecting the mathematical models obtained in the step 2 to form a turboset model. According to the method, the corresponding general basic model architecture is constructed in an object-oriented manner by utilizing the Modelica language, then the general basic models are sequentially combined and connected based on the connect statement of the Modelica language to form different turboset models, and the simulation precision can be gradually improved and the simulation verification requirements of different design stages can be met by continuously refining the basic models.

Description

Technical Field

[0001] The invention relates to the field of steam turbine unit design, and in particular to a modeling and simulation method for a large marine steam turbine unit based on the Modelica language. Background Art

[0002] The ship power system involves multiple large steam turbine units, which play a key role in the power system. Through synergy, they effectively convert thermal energy into mechanical power to drive the ship forward. Steam turbine units are usually composed of multiple closely matched components and are relatively complex, involving multiple components such as steam turbines, reducers, and regulating valves. And according to the different stages of steam turbine units, there are multiple stages such as single-stage and double-stage.

[0003] The existing modeling and simulation of steam turbine units are mostly based on simulation platforms such as ANSYS, using process-oriented modeling methods to achieve simulation of flow field, structural strength, thermal field, etc. of steam turbine units. However, only single simulation can be achieved for flow field, structural strength, thermal field, etc., and multi-physical quantity fusion cannot be achieved. Repeated modeling is required for different simulation targets. Moreover, when the simulation results of the steam turbine unit do not meet the design requirements, the entire steam turbine unit needs to be re-modeled, which is time-consuming.

[0004] In view of the above pain points, the field of ship power system design urgently needs an efficient steam turbine unit modeling and simulation method. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a large-scale marine steam turbine unit modeling and simulation method based on the Modelica language. The Modelica language is used to construct a corresponding general basic model architecture in an object-oriented manner, and then the general basic models are orderly combined and connected based on the connect statement of the Modelica language to form different steam turbine unit models.

[0006] The object of the present invention is achieved through the following technical scheme, a large-scale marine steam turbine modeling simulation method, comprising the following steps:

[0007] Step 1: Decompose the steam turbine unit model into several basic models according to the topological structure and physical characteristics of the steam turbine;

[0008] Step 2: For the physical model corresponding to each basic model, a declarative modeling method is used to convert it into a mathematical model in the form of equation expression;

[0009] Step 3: orderly combine and connect the mathematical models obtained in step 2 to form a steam turbine unit model.

[0010] Preferably, in step 1, the basic model is a universal minimum construction unit in the steam turbine unit model.

[0011] Preferably, in step 1, the basic model at least includes a steam regulating valve model, a steam turbine model, a steam-water separator model, a reducer model and a shaft model.

[0012] Preferably, in step 2, the physical models corresponding to each basic model are declaratively modeled based on the Modelica language.

[0013] Preferably, in step 2, the basic model equation constructed should be consistent with the form in the textbooks and literature.

[0014] Preferably, in step 3, the basic models are connected based on the Modelica connector model to form a steam turbine unit model.

[0015] Preferably, in step 3, the connector model includes at least a fluid connector and a mechanical connector.

[0016] Preferably, after the steam turbine unit model is constructed, the basic model particles are continuously refined to continuously improve the simulation accuracy.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The present invention provides a modeling and simulation method for a large-scale marine steam turbine unit based on the Modelica language. The Modelica language is used, according to the actual physical process of the model, an object-oriented declarative modeling method is adopted, and a basic model of a steam turbine, a reducer, etc. of the steam turbine unit is described in the form of equations to construct the basic model. According to the actual physical structure of the steam turbine unit, based on the connect statement of the Modelica language, the universal basic model is orderly combined and connected to form a multi-scheme steam turbine unit model. The model has good reusability, reconfigurability, and scalability, and can realize the rapid construction of steam turbine unit schemes of different stages according to needs, support multi-scheme demonstration, and improve design efficiency. By continuously refining the basic model, the simulation accuracy can be gradually improved to meet the simulation verification requirements of different design stages. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of a modeling and simulation method for a large marine steam turbine unit in an embodiment of the present invention;

[0020] Figure 2 It is a structural diagram of the main steam turbine gear unit system in an embodiment of the present invention;

[0021] Figure 3 This is a structural diagram of the main steam turbine gear unit model based on the Modelica language in an embodiment of the present invention;

[0022] Figure 4 This is a flow chart of continuous simulation verification in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0024] like Figure 1 As shown, the technical solution of the present invention provides a large-scale marine steam turbine modeling and simulation method, comprising the following steps:

[0025] Step 1: Decompose the steam turbine unit model into several basic models according to the topological structure and physical characteristics of the steam turbine;

[0026] Step 2: For the physical model corresponding to each basic model, a declarative modeling method is used to convert it into a mathematical model in the form of equation expression;

[0027] Step 3: orderly combine and connect the mathematical models obtained in step 2 to form a steam turbine unit model.

[0028] In one embodiment of the present invention, a method for decomposing a basic model of a steam turbine unit model for step 1 is provided. The Modelica language is used to construct a corresponding general basic model framework in an object-oriented manner, including a regulating valve model, a steam turbine model, a reducer model, etc. The steam turbine unit model is decomposed into several basic models according to the physical structure and operation mechanism, including a steam regulating valve model, a steam turbine model, a steam-water separator model, a reducer model, and a shaft model, which are the universal minimum structural units in the steam turbine unit model. The specific steps are as follows:

[0029] Step 1.1, determine the model goal: According to the task of the steam turbine unit, determine the model's goal and extended use, and clarify the information that must be obtained through the model and the information that the model does not need to consider. For example, the goal can be to complete the control of the steam flow of the steam turbine according to the control signal received by the steam inlet regulating valve, and further control the output shaft power of the steam turbine.

[0030] Step 1.2: Build a conceptual model. The conceptual model is a block diagram of the steam turbine system, such as Figure 2 As shown, it is to assist in analyzing the principles and mechanisms of the main phenomena of the system, help to fully understand the physical system, and reflect the modeling ideas.

[0031] In one embodiment of the present invention, in step 2, based on the connect statement of the Modelica language, the universal basic models are orderly combined and connected, and different combination schemes can form different steam turbine unit models, which specifically includes the following steps:

[0032] Based on the Modelica language, the physical models corresponding to each basic model are transformed into mathematical models in the form of equations using a declarative modeling method and object-oriented expression. Each mathematical equation of the model is independently written in the most natural form, without the need to specify the input and output variables and the order of solving the equations, and has non-causal characteristics. The equations are kept consistent with the form in textbooks and literature as much as possible to ensure readability and knowledge accumulation.

[0033] This embodiment takes the stage module of a steam turbine as an example to elaborate on the above process. The stage module of a steam turbine is a general module that can establish the entire working stage of a multi-stage steam turbine or the intermediate stage of a steam turbine. The steam turbine model obtains the stage outlet pressure and specific enthalpy based on the Flugel formula, calculates the stage group power based on the steam turbine ellipse formula, and calculates the turbine shaft work based on the energy conservation law.

[0034]

[0035] P=k·W 01 ·(H1-H)(2)

[0036]

[0037] Among them, W 01 is the flow rate under the current working condition of this stage, W0 is the flow rate under the design working condition of this stage, P 01 is the pressure under the current working condition of this stage, P0 is the pressure under the design working condition of this stage, P g1 is the back pressure under the current working condition of this stage, P1 is the back pressure under the design working condition of this stage, P is the unit power of this stage, k is the power coefficient of this stage, H is the steam outlet specific enthalpy, H1 is the steam inlet specific enthalpy, H 10 is the rated steam inlet specific enthalpy, N is the turbine speed, and η is the turbine efficiency.

[0038] The transformation of other basic models of the steam turbine unit is similar to the above example and will not be elaborated here.

[0039] In one embodiment of the present invention, in step 3, the basic model reorganization includes the following steps:

[0040] Based on the Modelica connector, the basic model is connected to form a steam turbine unit model. The various components contained in the basic model communicate with other components or the outside world through connectors. Through this connection relationship, the equilibrium equation is automatically established in the system. The connector contains various physical quantities that need to be described, such as pressure and flow in fluid elements. The connector model is divided into fluid connectors and mechanical connectors. Fluid connectors are used between the pressure stage blades and steam, and mechanical connectors are used to connect the turbine main shaft with other equipment. Based on the general basic model and the connector, Modelica is used to build a steam turbine unit model such as Figure 3 shown.

[0041] As a further optimization of the above embodiment, Figure 4 As shown in the figure, the granularity of the basic model is different at different design stages. As the equipment design progresses, the basic model particles can be continuously refined, which can provide support for the continuous verification of the simulation model. As the basic model particles continue to be refined, the simulation accuracy continues to improve, which can meet the simulation verification needs of different design stages.

[0042] The present invention has the following advantages:

[0043] 1. Decompose the steam turbine model according to physical characteristics, and use the Modelica language to build the corresponding general basic model architecture in an object-oriented manner, including the control valve model, steam turbine model, reducer model, etc., and may involve multiple physical quantities such as mechanics, thermal force, and flow field. Based on the connect statement of the Modelica language, the steam turbine model can be formed by orderly combining and connecting the general basic models. And through different combinations of basic models, multiple schemes of the steam turbine can be realized, which is convenient for multi-scheme demonstration. Compared with the process-oriented modeling method, it avoids repeated modeling processes.

[0044] 2. Based on the Modelica language, the physical models corresponding to each basic model are converted into mathematical models in the form of equations using declarative modeling methods. Each mathematical equation of the model is independently written in the most natural form, without the need to specify the input and output variables and the order of solving the equations. It has non-logical characteristics, reduces the difficulty of modeling, and improves modeling efficiency.

[0045] 3. As the equipment design deepens, the basic model particles can be continuously refined, which can provide support for the continuous verification of the simulation model. As the basic model particles continue to be refined, the simulation accuracy continues to improve, which can meet the simulation verification needs of different design stages.

[0046] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A modeling and simulation method for a large marine steam turbine unit, characterized in that: The method comprises the following steps: Step 1: Decompose the steam turbine unit model into several basic models according to the topological structure and physical characteristics of the steam turbine; Step 2: For the physical model corresponding to each basic model, a declarative modeling method is used to convert it into a mathematical model in the form of equation expression; Step 3: orderly combine and connect the mathematical models obtained in step 2 to form a steam turbine unit model.

2. A large-scale marine steam turbine modeling and simulation method as claimed in claim 1, characterized in that: In the step 1, the basic model is the universal minimum construction unit in the steam turbine unit model.

3. A large-scale marine steam turbine modeling and simulation method as claimed in claim 2, characterized in that: In the step 1, the basic model at least includes a steam regulating valve model, a steam turbine model, a steam-water separator model, a reducer model and a shaft model.

4. A large-scale marine steam turbine modeling and simulation method as claimed in claim 1, characterized in that: In the step 2, the physical models corresponding to each basic model are declaratively modeled based on the Modelica language.

5. A large-scale marine steam turbine modeling and simulation method as claimed in claim 4, characterized in that: In step 2, the basic model equation constructed must be consistent with the form in the textbooks and literature.

6. A large-scale marine steam turbine modeling and simulation method as claimed in claim 1, characterized in that: In the step 3, the basic model is connected based on the Modelica connector model to form a steam turbine unit model.

7. A large-scale marine steam turbine modeling and simulation method as claimed in claim 6, characterized in that: In step 3, the connector model includes at least a fluid connector and a mechanical connector.

8. A large-scale marine steam turbine modeling and simulation method as claimed in claim 1, characterized in that: After the steam turbine unit model is constructed, the basic model particles are continuously refined to continuously improve the simulation accuracy.

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