Method for optimizing design on number of regulating stage nozzles of steam turbine based on improved genetic algorithm

A technology for improving the genetic algorithm and optimization method, which is applied in the design and optimization field of the number of nozzles in the regulating stage of steam turbines, and can solve the problems that the fully open or fully closed state cannot be guaranteed, does not conform to the theme of the times, and the valve opening in the working load area is small.

Active Publication Date: 2012-09-19
NANJING POWER HORIZON INFORMATION TECH CO LTD
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Problems solved by technology

[0004] At present, the number of nozzles corresponding to each steam chamber in the steam turbine nozzle device produced in China is usually the same, and most of them follow the previous experience data, which cannot match the basic load point of the steam turbine well, resulting in the relative valve opening in the working load area. smaller
In the case of a small opening, the valve is likely to cause a large throttling loss, which significantly reduces its relative internal efficiency. Therefore, in the structural design of the nozzle device, try to ensure that the regulating valve at the working load point remains fully open or fully closed.
Generally, the working load point of the steam turbine unit will change with the demand of the power grid. When multiple loads are actually given, in order to make the steam turbine reach the required working point, the control level valves on the nozzle devices with the same number of nozzles in each group generally cannot guarantee full control. Open or fully closed state, resulting in a certain degree of throttling loss
At present, the commonly used load point of domestic units is 70% to 80% of the rated power, and its relative internal efficiency is only about 45%, which does not meet the current theme of energy conservation and environmental protection, and seriously restricts the improvement of economic benefits of steam turbine generator units in my country.

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  • Method for optimizing design on number of regulating stage nozzles of steam turbine based on improved genetic algorithm
  • Method for optimizing design on number of regulating stage nozzles of steam turbine based on improved genetic algorithm
  • Method for optimizing design on number of regulating stage nozzles of steam turbine based on improved genetic algorithm

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specific Embodiment approach 1

[0043] Specific implementation mode one: combine figure 1 Describe this embodiment, the optimization method of this embodiment is to realize based on following model:

[0044] Y=(xgz 1 -Ge 1 ) 2 +(xgz 2 -Ge 2 ) 2 +......+(xgz l -Ge l ) 2 ,

[0045] l is the number of load points, and based on the improved genetic algorithm, the combination of the optimal number of nozzles at a given load point is obtained: the specific process is as follows,

[0046] Step 1. Initial population setting: set constraints:

[0047] First constraint: X 1 +X 2 +......+X n =X z , X z =const 2-2

[0048] The second constraint: X min ≤X i ≤X max , i=1, 2, ..., n; X min = const, X max = const 2-3

[0049] Xi represents the number of nozzles corresponding to the i-th valve, const represents a constant, and is coded by a floating point number, and the coding interval is [X min , X max ]

[0050] The initial population can be represented by a (n-1)×m matrix:

[0051] ...

specific Embodiment approach 2

[0082] Specific implementation mode two: the calculation method of the adjustment step change working condition described in step two of this embodiment mode is:

[0083] Step 21. Calculate the theoretical flow rate of each valve in the regulating stage: G i =G e · ξ k , where G k is the theoretical flow at the load point, G e is the rated flow of the steam turbine, ξ k is the percentage of steam turbine operating power to rated power at the load point, k=1, 2,...l, k is the number of work load points;

[0084] Step 22. Calculate the actual flow rate G from the number of nozzles of each valve and the corresponding valve opening kj :

[0085] G kj = 0.648 A nk p 0 k ρ 0 ...

specific Embodiment approach 3

[0091] 1. The user specifies the common working load point of the steam turbine unit, the sliding pressure operation curve, the total number of valve nozzles of the regulating stage, the value range of the number of nozzles in a single nozzle group, and the characteristic curve of the regulating stage calculated by the variable operating conditions of the regulating stage.

[0092] 2. Optimizing the number of nozzles: If for all the load points given by the user, the corresponding control valve opening (full opening) combination can be found under the condition of the optimally designed nozzle group, then the optimization goal has been achieved. In the analysis and calculation, the degree of deviation between the calculated flow rate when the valve is fully open or fully closed and the theoretical flow rate of a given load is used as the measurement basis. During the process, the operating time of different commonly used load points is fully considered, and the operating frequen...

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Abstract

The invention specifically relates to a method for optimizing the design on the number of regulating stage nozzles of a steam turbine based on an improved genetic algorithm. The method disclosed by the invention aims at optimizing the number of the regulating stage nozzles of the steam turbine under multiple load points, so that a unit can stably run under different loads, and the nozzles can constitute more valve points as far as possible, thereby allowing the damper loss to be minimum and the intra-regulating-stage efficiency to be maximum. The method mainly comprises the following steps of: based on the improved genetic algorithm, determining the optimal nozzle number combination, the regulating-stage rear flow, the downstream pressure of each valve and the air flow force which can be achieved through outputting a load point in a situation that the deviation value Y between actual flow and theoretical flow is minimum: and through improved genetic codes and a fitness function, carrying out a genetic algorithm operation, and then outputting the optimal nozzle number combination achieved in the situation that the deviation value Y between the actual flow and the theoretical flow is minimum. The method disclosed by the invention can improve the speed of an optimization process and the accuracy of optimization results.

Description

technical field [0001] The invention relates to a design optimization method for the number of nozzles of a steam turbine regulating stage. Background technique [0002] A steam turbine is a rotating machine powered by steam and converts the energy of steam into mechanical work. It is widely used in modern large-scale power generation systems. As a typical process energy, the non-storage of electric energy makes the motor power largely depend on the user's electricity consumption. Therefore, the steam turbine must constantly adjust its power to keep the motor power in balance with the changing load of the outside world. The most direct and effective way to change the power of a steam turbine is to control its air intake, that is, to distribute steam to the steam turbine. At present, the existing steam distribution methods include nozzle steam distribution, throttling steam distribution, sliding pressure steam distribution, full electric regulation "valve management" steam ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06N3/12
Inventor 刘金福李飞万杰张怀鹏张可浩游尔胜付云峰蔡鼎王一丰
Owner NANJING POWER HORIZON INFORMATION TECH CO LTD
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