阅读说明：本技术 低压汽轮机的自动控制方法及系统、发电系统 (Automatic control method and system of low-pressure steam turbine and power generation system ) 是由 王丙峰 肖官和 张晓峰 郭丽慧 于 2021-10-29 设计创作，主要内容包括：本申请属于自动控制技术领域,具体涉及一种拖动异步发电机的低压汽轮机的自动控制方法,低压汽轮机设置有与低压汽轮机的进汽口连通的并联的第一进汽支路和第二进汽支路,第一进汽支路和第二进汽支路均设置有主汽速关阀和进汽调节阀,该方法包括：S10、获取异步发电机实时的电功率测量值、预设的电功率设定值和电功率限定值；S20、计算电功率测量值和电功率限定值的偏差值,根据偏差值选择通过PID运算得到开度调节值、反馈控制进汽调节阀的开度或者通过比例调节器输出增益值控制进汽调节阀关闭。通过本申请的方法调节汽轮机的进汽量可以有效控制汽轮异步发电机的输出电功率,防止汽轮机因超额定出力而损坏,满足低压汽轮机的控制需求。(The application belongs to the technical field of automatic control, concretely relates to automatic control method for a low-pressure steam turbine dragging an asynchronous generator, wherein the low-pressure steam turbine is provided with a first steam inlet branch and a second steam inlet branch which are connected in parallel and communicated with a steam inlet of the low-pressure steam turbine, the first steam inlet branch and the second steam inlet branch are both provided with a main steam speed closing valve and a steam inlet regulating valve, and the method comprises the following steps: s10, acquiring a real-time electric power measured value, a preset electric power set value and an electric power limit value of the asynchronous generator; and S20, calculating a deviation value of the electric power measured value and the electric power limit value, and selecting to obtain an opening degree regulating value through PID operation according to the deviation value, and controlling the opening degree of the steam inlet regulating valve in a feedback mode or controlling the steam inlet regulating valve to be closed through a gain value output by the proportional regulator. The method can effectively control the output electric power of the turbine asynchronous generator by adjusting the steam inlet quantity of the steam turbine, prevent the steam turbine from being damaged due to over-rated output and meet the control requirement of the low-pressure steam turbine.)

1. The automatic control method of the low-pressure turbine for dragging the asynchronous generator is characterized in that the low-pressure turbine is provided with a first steam inlet branch and a second steam inlet branch which are communicated with a steam inlet of the low-pressure turbine and connected in parallel, the first steam inlet branch and the second steam inlet branch are both provided with a main steam speed closing valve and a steam inlet regulating valve, and the method comprises the following steps:

s10, acquiring a real-time electric power measured value, a preset electric power set value and an electric power limit value of the asynchronous generator;

and S20, calculating a deviation value of the electric power measured value and the electric power limit value, and selecting to obtain an opening degree regulating value through PID operation according to the deviation value, and performing feedback control on the opening degree of the steam inlet regulating valve or outputting a gain value through a proportional regulator to control the closing of the steam inlet regulating valve.

2. The method for automatically controlling a low pressure turbine of a motoring asynchronous generator according to claim 1, characterized in that S20 comprises:

when the electric power measured value is greater than or equal to the electric power limit value, controlling the steam inlet regulating valve to be closed through a proportional regulator output gain value;

when the electric power measured value is smaller than the electric power limit value, an opening degree adjusting value is obtained through PID operation, and the opening degree of the steam inlet adjusting valve is subjected to feedback control.

3. The method for automatically controlling the low pressure turbine of a traction asynchronous generator according to claim 2, characterized in that said PID operations are:

wherein u (x) is an opening degree adjustment value, K_pIs a proportionality coefficient, T_iIs an integral time constant, T_dIs the differential time constant, e (t) is the offset value.

4. The method for automatically controlling a low pressure turbine of a traction asynchronous generator according to claim 2, characterized in that said proportioner operates by:

f(x)＝K_p2[e(t)]

wherein, K_p2Is the second scaling factor, and f (x) is the gain value.

5. The method for automatically controlling a low pressure turbine driving an asynchronous generator according to claim 2, wherein said controlling the closing of said admission control valve by means of a proportional regulator output gain value comprises:

and when the electric power measured value is larger than or equal to the electric power limit value, controlling the steam inlet regulating valve to reduce the steam inlet amount until the electric power measured value is reduced to a preset safety value.

6. The method for automatically controlling a low pressure turbine driving an asynchronous generator according to claim 5, characterized in that said preset safety value is equal to said electric power set point.

7. The utility model provides a drag asynchronous generator's low pressure turbine's automatic control system, its characterized in that, low pressure turbine is provided with the parallelly connected first admission branch road and the second admission branch road with the admission mouth intercommunication of low pressure turbine, first admission branch road and second admission branch road all are provided with main vapour speed and close valve and admission governing valve, and this system includes: the device comprises a power sensor, a comparator, a selector, a PID regulator and a proportion regulator; the power sensor is arranged at the output end of the asynchronous generator, the output end of the power sensor is respectively connected with the input ends of the comparator, the PID regulator and the proportional regulator, the output ends of the comparator, the PID regulator and the proportional regulator are respectively connected with the corresponding port of the input end of the selector, and the output end of the selector is connected with the control port of the steam inlet regulating valve.

8. The automatic control system of the low pressure turbine of a traction asynchronous generator according to claim 7, characterized in that,

the power sensor is used for measuring the electric power value output by the asynchronous generator in real time to obtain an electric power measured value;

the comparator is used for taking the electric power measured value as input, comparing the electric power measured value with a preset electric power limit value to obtain a first comparison result and outputting the first comparison result to the selector;

the PID regulator is used for taking the electric power measured value and a preset electric power set value as input, obtaining an opening degree regulating value through PID operation and outputting the opening degree regulating value to the selector;

the proportional regulator is used for taking the electric power measured value and the electric power set value as input, obtaining a gain value through proportional operation and outputting the gain value to the selector;

and the selector is used for selecting and outputting the opening degree regulating value or the gain value to a control port of the steam inlet regulating valve by taking the first comparison result as a judgment condition.

9. The automatic control system for the low pressure turbine of a motoring asynchronous generator according to claim 8, characterized in that said power sensor is one of a power meter, a current meter and a multifunction meter.

10. A power generation system comprising an asynchronous generator, a low pressure turbine which drives said asynchronous generator, and an automatic control system for the low pressure turbine which drives the asynchronous generator according to any one of claims 7 to 9.

Technical Field

The application belongs to the technical field of automatic control, and particularly relates to an automatic control method of a low-pressure turbine.

Background

In a control system of a low-pressure turbine for dragging an asynchronous generator, the conventional control mode is to measure the power (or current) of the generator through a power (or current) meter, compare the power (or current) with a target power (or current) value, and realize automatic adjustment through a PID (proportion integration differentiation) algorithm of a control system such as a regulator or a DCS (distributed control system) according to deviation, and also realize manual adjustment.

Because the low-pressure turbine is attached to a main system for realizing the main industrial production flow, the steam inlet parameter of the low-pressure turbine fluctuates, and the opening degree of the steam inlet adjusting door is a determined reasonable opening degree value alpha%, the low-pressure turbine is not generally put into automatic adjustment, so that in the practical application, the electric power output by the low-pressure turbine fluctuates along with the fluctuation of the steam inlet parameter. When the low-pressure turbine operates as an auxiliary engine system in an industrial production process, the condition that boundary conditions deviate from design values is easy to occur, so that the existing control mode easily causes the turbine to be damaged due to over-rated output, and the control requirement of the low-pressure turbine cannot be met.

Disclosure of Invention

Technical problem to be solved

In view of the above drawbacks and deficiencies of the prior art, the present application provides an automatic control method and system for a low pressure turbine of a dragging asynchronous generator, and a power generation system.

(II) technical scheme

In order to achieve the purpose, the technical scheme is as follows:

in a first aspect, an embodiment of the present application provides an automatic control method for a low pressure turbine that drives an asynchronous generator, where the low pressure turbine is provided with a first steam inlet branch and a second steam inlet branch that are connected in parallel and communicated with a steam inlet of the low pressure turbine, and the first steam inlet branch and the second steam inlet branch are both provided with a main steam speed closing valve and a steam inlet regulating valve, and the method includes:

s10, acquiring a real-time electric power measured value, a preset electric power set value and an electric power limit value of the asynchronous generator;

and S20, calculating a deviation value of the electric power measured value and the electric power limit value, and selecting to obtain an opening degree regulating value through PID operation according to the deviation value, and performing feedback control on the opening degree of the steam inlet regulating valve or outputting a gain value through a proportional regulator to control the closing of the steam inlet regulating valve.

Optionally, S20 includes:

when the electric power measured value is greater than or equal to the electric power limit value, controlling the steam inlet regulating valve to be closed through a proportional regulator output gain value;

when the electric power measured value is smaller than the electric power limit value, an opening degree adjusting value is obtained through PID operation, and the opening degree of the steam inlet adjusting valve is subjected to feedback control.

Optionally, the PID operation is:

wherein u (x) is an opening degree adjustment value, K_pIs a proportionality coefficient, T_iIs an integral time constant, T_dIs the differential time constant, e (t) is the offset value.

Optionally, the operation of the proportional regulator is:

f(x)＝K_p2[e(t)]

wherein, K_p2Is the second scaling factor, and f (x) is the gain value.

Optionally, controlling the steam inlet regulating valve to close by a proportional regulator output gain value comprises:

and when the electric power measured value is larger than or equal to the electric power limit value, controlling the steam inlet regulating valve to reduce the steam inlet amount until the electric power measured value is reduced to a preset safety value.

Optionally, the preset safe value is equal to the electric power set value.

In a second aspect, an embodiment of the present application provides an automatic control system for a low pressure turbine that drags an asynchronous generator, the low pressure turbine is provided with a first steam inlet branch and a second steam inlet branch that are connected in parallel and communicated with a steam inlet of the low pressure turbine, the first steam inlet branch and the second steam inlet branch are both provided with a main steam speed closing valve and a steam inlet regulating valve, and the system includes: the device comprises a power sensor, a comparator, a selector, a PID regulator and a proportion regulator; the power sensor is arranged at the output end of the asynchronous generator, the output end of the power sensor is respectively connected with the input ends of the comparator, the PID regulator and the proportional regulator, the output ends of the comparator, the PID regulator and the proportional regulator are respectively connected with the corresponding port of the input end of the selector, and the output end of the selector is connected with the control port of the steam inlet regulating valve.

Optionally, the power sensor is configured to measure an electric power value output by the asynchronous generator in real time to obtain an electric power measurement value;

the comparator is used for taking the electric power measured value as input, comparing the electric power measured value with a preset electric power limit value to obtain a first comparison result and outputting the first comparison result to the selector;

the PID regulator is used for taking the electric power measured value and a preset electric power set value as input, obtaining an opening degree regulating value through PID operation and outputting the opening degree regulating value to the selector;

the proportional regulator is used for taking the electric power measured value and the electric power set value as input, obtaining a gain value through proportional operation and outputting the gain value to the selector;

and the selector is used for selecting and outputting the opening degree regulating value or the gain value to a control port of the steam inlet regulating valve by taking the first comparison result as a judgment condition.

Optionally, the power sensor is one of a power meter, a current meter and a multifunction meter.

In a third aspect, embodiments of the present application provide a power generation system comprising an asynchronous generator, a low pressure turbine that powers the asynchronous generator, and an automatic control system for the low pressure turbine that powers the asynchronous generator as described in any of the second aspects above.

(III) advantageous effects

The beneficial effect of this application is: the application provides a drag asynchronous generator's automatic control method of low pressure steam turbine, and the low pressure steam turbine is provided with the parallelly connected first admission branch road and the second admission branch road that communicate with the admission mouth of low pressure steam turbine, and first admission branch road and second admission branch road all are provided with main vapour fast valve and admission governing valve, and the method includes: s10, acquiring a real-time electric power measured value, a preset electric power set value and an electric power limit value of the asynchronous generator; and S20, calculating a deviation value of the electric power measured value and the electric power limit value, selecting an opening degree regulating value through PID operation according to the deviation value, and controlling the opening degree of the steam inlet regulating valve in a feedback mode or controlling the steam inlet regulating valve to be closed through a gain value output by the proportional regulator. The automatic control method for the low-pressure turbine dragging the asynchronous generator adjusts the steam inlet quantity of the turbine, can effectively control the output electric power of the turbine asynchronous generator, prevents the turbine from being damaged due to over-rated output, and meets the control requirement of the low-pressure turbine.

Drawings

The application is described with the aid of the following figures:

FIG. 1 is a schematic flow chart illustrating a method for automatically controlling a low pressure turbine of a power plant of an asynchronous generator according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of an automatic control system for a low pressure turbine of a traction asynchronous generator according to another embodiment of the present application;

fig. 3 is a schematic structural diagram of a power generation system in another embodiment of the present application.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings. It is to be understood that the following specific examples are illustrative of the invention only and are not to be construed as limiting the invention. In addition, it should be noted that, in the case of no conflict, the embodiments and features in the embodiments in the present application may be combined with each other; for convenience of description, only portions related to the invention are shown in the drawings.

Example one

The embodiment of the application provides an automatic control method for a low-pressure steam turbine dragging an asynchronous generator, wherein the low-pressure steam turbine is provided with a first steam inlet branch and a second steam inlet branch which are communicated with a steam inlet of the low-pressure steam turbine and connected in parallel, and the first steam inlet branch and the second steam inlet branch are both provided with a main steam speed closing valve and a steam inlet regulating valve. Fig. 1 is a schematic flow chart of an automatic control method for a low pressure turbine dragging an asynchronous generator according to an embodiment of the present application, and as shown in fig. 1, the automatic control method for the low pressure turbine dragging an asynchronous generator according to the present embodiment includes:

s10, acquiring a real-time electric power measured value, a preset electric power set value and an electric power limit value of the asynchronous generator;

and S20, calculating a deviation value of the electric power measured value and the electric power limit value, selecting an opening degree regulating value through PID operation according to the deviation value, and controlling the opening degree of the steam inlet regulating valve in a feedback mode or controlling the steam inlet regulating valve to be closed through a gain value output by the proportional regulator.

The automatic control method for the low-pressure turbine dragging the asynchronous generator adjusts the steam inlet quantity of the turbine, can effectively control the output electric power of the turbine asynchronous generator, effectively prevents the turbine from being damaged due to over-rated output, and meets the control requirement of the low-pressure turbine.

In order to better understand the present invention, the steps in the present embodiment are explained below.

In this embodiment S10, the electric power setting value may be a fixed value preset by an operator according to work experience, or may be a power value calculated by a computer device according to a real-time work environment, which is not limited in this embodiment of the present application.

The electric power limit value may be a power value calculated from the maximum output electric power of the asynchronous generator.

Specifically, the electric power set value and the electric power limit value can be manually input by an operator according to actual conditions, or can be pre-stored in a server, and the system acquires the electric power set value and the electric power limit value from the server. The electrical power measurements may be obtained by a power sensor mounted at the generator outlet.

In this embodiment S20, due to the low pressure turbine, the related design boundary conditions include steam admission pressure, steam discharge pressure, steam admission amount, steam admission temperature, and steam discharge temperature; under the condition that the parameters are determined, the output power of the steam turbine is constant, the output power drags the generator through the steam turbine rotor to realize the determinable power generation capacity (power/current), and therefore, the electric power output to the outside can be continuously adjusted by adjusting the opening degree of the adjusting valve.

Specifically, S20 includes:

when the measured value of the electric power is larger than or equal to the limited value of the electric power, the steam inlet regulating valve is controlled to be closed through the output gain value of the proportional regulator;

when the electric power measured value is smaller than the electric power limit value, an opening degree regulating value is obtained through PID operation, and the opening degree of the steam inlet regulating valve is subjected to feedback control.

In this embodiment, PID refers to "proportional (proportional), integral (integral), derivative (derivative)"; the PID algorithm is a common control algorithm, and is applied to occasions where a certain physical quantity needs to be kept stable, such as maintaining balance, stabilizing electric power, stabilizing rotating speed and the like. In the present embodiment, the PID is used to control the adjustment of the actual value of the output electric power of the asynchronous generator to the set value of the electric power.

Specifically, the PID operation is:

wherein u (x) is an opening degree adjustment value, K_p1Is a first scale factor, T_iIs an integral time constant, T_dIs the differential time constant, e (t) is the offset value.

In this embodiment S20, the operation of the proportional regulator is:

f(x)＝K_p2[e(t)]

wherein, K_p2Is the second scaling factor, and f (x) is the gain value.

It should be noted that the second proportionality coefficient is largeAt a first scale factor, e.g. K can be preset_P2K is 2 to 3 times_P1。

The proportional regulator has larger proportional coefficient, and the regulation quality is reduced, but the proportional regulator can adapt to the change of the output power and can realize faster regulation than a PID regulator. The preset value of the target power of the proportional regulator can be synchronized with the set value of the PID regulator, or can be preset to a certain empirically safe output power set value, for example 50% Pe (rated power).

In this embodiment, the controlling of the closing of the steam inlet regulating valve by the output gain value of the proportional regulator in S20 may include:

and when the electric power measured value is greater than or equal to the electric power limit value, controlling the steam inlet regulating valve to reduce the steam inlet amount until the electric power measured value is reduced to a preset safety value.

Preferably, the preset safety value is equal to the electric power set value.

In summary, according to the automatic control method for the low pressure turbine driving the asynchronous generator provided by the present application, when the measured value of the electric power is smaller than the electric power limit value, the PID calculation is performed on the deviation between the measured value of the electric power and the set value of the electric power, so that the fast response can be achieved, the fast and stable control effect can be achieved, and when the measured value of the electric power is greater than or equal to the electric power limit value, the steam inlet regulating valve is controlled to close by the output gain value of the proportional regulator, thereby preventing the turbine from being damaged due to the over-rated output.

Example two

Fig. 2 is a schematic structural diagram of an automatic control system of a low pressure turbine for dragging an asynchronous generator according to another embodiment of the present application, in which the low pressure turbine 100 is provided with a first steam inlet branch and a second steam inlet branch connected in parallel and communicated with a steam inlet of the low pressure turbine, and the first steam inlet branch and the second steam inlet branch are both provided with a main steam speed closing valve and a steam inlet regulating valve, as shown in fig. 2, the system includes: a power sensor 310, a comparator 320, a selector 340, a PID regulator 332, a proportional regulator 331; the power sensor 310 is disposed at the output end of the asynchronous generator, and the output end of the power sensor 310 is respectively connected with the comparator 320, the PID regulator 332 and the ratioThe input end of the example regulator 331 is connected, the output ends of the comparator 320, the PID regulator 332 and the proportional regulator 331 are respectively connected with the corresponding ports of the input end of the selector 340, and the output end of the selector 340 is connected with the control port of the steam inlet regulating valve. Wherein, P₁Is an electric power limit value, P₀Is the electrical power set point.

The following describes the structure of the system in detail.

In this embodiment, the first steam inlet branch is provided with a first main steam quick-closing valve 411 and a first steam inlet regulating valve 412, and the second steam inlet branch is provided with a second main steam quick-closing valve 421 and a second steam inlet regulating valve 422.

In this embodiment, the power sensor 310 is configured to measure an electric power value output by the asynchronous generator 200 in real time to obtain an electric power measurement value;

a comparator 320 for comparing the measured value of the electric power with a predetermined electric power limit value to obtain a first comparison result and outputting the first comparison result to the selector 340;

the PID regulator 332 for obtaining an opening degree regulation value through PID calculation with the electric power measurement value and a preset electric power setting value as inputs and outputting to the selector 340;

a proportional regulator 331 for receiving the electric power measurement value and the electric power setting value as input, obtaining a gain value through proportional operation, and outputting the gain value to the selector 340;

and the selector 340 is configured to select to output the opening degree adjustment value or the gain value to the control port of the steam inlet adjustment valve by using the first comparison result as a determination condition.

Specifically, the power sensor 310 may be one of a power meter, a current meter, and a multifunction meter.

It should be noted that the power sensor 310 is only an exemplary illustration, and does not specifically limit the power sensor 310.

In the control system of the embodiment, the electric power set value and the deviation of the electric power measurement signal are compared as the input of the PID regulator 332, the output of the PID regulator 332 is connected to a selector 340, the output of the selector 340 is firstly connected to a manual setter (which can complete the setting and indicating functions), wherein the electric power measurement signal can be obtained by a power meter (or an ammeter and a multifunctional meter) arranged at the outlet of the generator; in order to accord with the characteristics of an auxiliary system, namely the output power changes along with the change of the steam inlet pressure of a unit, the working mode of the regulating system is indicated in a mode of realizing the output of a regulator according to the comparison deviation of an electric power set value and an electric power measurement signal, a PID (proportion integration differentiation) parameter of the regulator can be set to a reasonable value according to the system characteristics, the output of the regulator forms a valve opening (closing) instruction after a manual selection link is forcibly switched, and the valve is opened when a measured value is smaller than the set value; otherwise, the valve is closed. Meanwhile, when the measured value of the electric power is greater than or equal to the electric power limit value, the operation mode with the override control is executed. In this way, the steam inlet regulating valve is normally kept at a reasonable opening according to the expected output electric power level, the output electric power changes along with the fluctuation of the steam inlet parameter, when the output electric power (or the current of the generator) exceeds the limit, the override control of the steam inlet regulating valve is executed, the regulating valve is automatically closed when the limit is exceeded, the closing action is stopped until the electric power (or the current of the generator) returns to a safe and reasonable value, and the steam inlet regulating valve is kept at a new opening to continuously output the electric power continuously changing along with the fluctuation of the steam inlet parameter.

EXAMPLE III

Fig. 3 is a schematic structural diagram of a power generation system in another embodiment of the present application.

In a third aspect of the present application, there is provided a power generation system according to the third embodiment, the system including an asynchronous generator 200, a low pressure turbine 100 for driving the asynchronous generator, and an automatic control system 300 for the low pressure turbine for driving the asynchronous generator according to any one of the second embodiment.

The low pressure turbine 100 is provided with a first steam inlet branch and a second steam inlet branch which are connected in parallel and communicated with a steam inlet of the low pressure turbine 100, and the first steam inlet branch and the second steam inlet branch are both provided with a main steam quick closing valve and a steam inlet regulating valve. The automatic control system 300 controls the opening of the steam intake regulating valve based on the electric power measurement of the asynchronous generator.

It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. The use of the terms first, second, third and the like are for convenience only and do not denote any order. These words are to be understood as part of the name of the component.

Furthermore, it should be noted that in the description of the present specification, the description of the term "one embodiment", "some embodiments", "examples", "specific examples" or "some examples", etc., means that a specific feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, the claims should be construed to include preferred embodiments and all changes and modifications that fall within the scope of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include such modifications and variations.