Acceleration Method for Steam Temperature Control Signal and Secondary Superheated Steam Temperature Control System

Abstract

The present application discloses a method for accelerating a steam temperature control signal and a secondary superheated steam temperature control system. By using an input differentiator, the steam temperature control signal is signal-converted to obtain a first differential output signal; by using a positive feedback accelerator, the first differential output signal is accelerated to obtain a steam temperature acceleration control signal; by using a negative differentiator, the accelerated signal is signal-converted to obtain a second differential output signal; by using a negative output controller, the negative acceleration signal in the second differential output signal is extracted; by using an addition link, the first differential output signal and the negative acceleration signal are added to obtain a steam temperature acceleration control signal of the differential signal. The present application negatively accelerates the process signal through a negative differential accelerator, so that the negative signal with a downward trend in the process signal is output in advance, thereby performing negative over-temperature control in advance, reducing control lag, and further solving the negative over-temperature problem existing in the secondary superheated steam temperature control system and enhancing the control effect.

Description

Technical Field

[0001] The present application relates to the technical field of process control of thermal power units, and particularly to a method for accelerating a steam temperature control signal and a secondary superheated steam temperature control system. Background Art

[0002] In the practice of process control of thermal power units, in the secondary superheated steam temperature control system of thermal power units, the problem of relatively large deviation of the secondary superheated steam temperature often occurs, that is, the deviation of the secondary superheated steam temperature value from the given value of the secondary superheated steam temperature is relatively large, and the negative over-temperature (that is, the secondary superheated steam temperature value is lower than the given steam temperature value) of the secondary superheated steam temperature control system is relatively serious.

[0003] Currently, for the problem of negative over-temperature of the secondary superheated steam temperature, the prior art adopts a one-position control method, that is, when the negative deviation of the secondary superheated steam temperature exceeds a certain amplitude, a fixed opening is added to the desuperheating water valve to control the water volume of the desuperheating water valve, so as to achieve the purpose of controlling the secondary superheated steam temperature. However, this method has a control lag problem, resulting in limited control effect. Summary of the Invention

[0004] The present application provides a method for accelerating a steam temperature control signal and a secondary superheated steam temperature control system to solve the technical problem of control lag existing in the current secondary superheat control system.

[0005] To solve the above technical problem, in a first aspect, the present application provides a method for accelerating a steam temperature control signal, which is applied to a negative differential accelerator. The negative differential accelerator includes an input differentiator, a positive feedback accelerator, a negative differentiator, a negative output controller, and an addition link;

[0006] Using the input differentiator, the steam temperature control signal is signal-converted to obtain a first differential output signal;

[0007] Using the positive feedback accelerator, the first differential output signal is accelerated to obtain an acceleration signal;

[0008] Using the negative differentiator, the acceleration signal is signal-converted to obtain a second differential output signal;

[0009] Using the negative output controller, the negative acceleration signal in the second differential output signal is extracted;

[0010] Using the addition link, an addition operation is performed on the first differential output signal and the negative acceleration signal to obtain a steam temperature acceleration control signal.

[0011] Preferably, the steam temperature control signal is a deviation signal between the superheated steam temperature signal and the given superheated steam temperature signal of the secondary superheated steam temperature control system.

[0012] Preferably, using the input differentiator to perform signal conversion on the steam temperature control signal to obtain a first differential output signal, including:

[0013] Using the input differentiator to convert the downward trend in the steam temperature control signal into a negative signal, and using the negative signal as the first differential output signal input to the positive feedback accelerator. The input differentiator is:

[0014]

[0015] where IND(s) is the transfer function of the input differentiator, T IND is the differential time constant of the input differentiator, and s is the Laplace operator.

[0016] Preferably, the positive feedback accelerator includes a positive feedback link, an accelerator, and a limiter. Using the positive feedback accelerator to accelerate the first differential output signal to obtain an acceleration signal, including:

[0017] Using the positive feedback link to control the accelerator to accelerate;

[0018] Using the accelerator to accelerate the negative signal in the first differential output signal to obtain a negative acceleration signal;

[0019] Using the limiter to limit the negative acceleration signal output by the accelerator to obtain the acceleration signal.

[0020] Preferably, the accelerator is:

[0021]

[0022] The limiter is:

[0023]

[0024] where I(s) is the transfer function of the accelerator, s is the Laplace operator, T I is the integral time constant of the accelerator, I(t) is the output signal of the accelerator, and IND(t) is the output signal of the input differentiator.

[0025] Preferably, the negative differentiator is:

[0026]

[0027] where D(s) is the transfer function of the negative differentiator, s is the Laplace operator, T D is the differential time constant of the negative differentiator.

[0028] Preferably, the negative output controller is:

[0029]

[0030] where NOC(t) is the output signal of the negative output controller, and D(t) is the output signal of the negative differentiator.

[0031] In a second aspect, the present application also provides a secondary superheated steam temperature control system, including a controller, where the controller includes a cascade proportional controller, an engineering fastest integrator, and a negative differential accelerator as described in the first aspect;

[0032] The cascade proportional controller is respectively connected to the engineering fastest integrator and the negative differential accelerator. The steam temperature control signal of the cascade proportional controller is a process signal, and the process signal is the deviation signal between the superheated steam temperature signal and the superheated steam temperature set signal of the secondary superheated steam temperature control system;

[0033] The controller is:

[0034] C(s) = K cpc [EFI(s) + NDSA(s)];

[0035] where C(s) is the transfer function of the controller, EFI(s) is the transfer function of the engineering fastest integrator, NDSA(s) is the transfer function of the negative differential accelerator, and K cpc is the gain of the cascade proportional controller.

[0036] Preferably, the transfer function of the engineering fastest integrator is:

[0037]

[0038] where EFPI(s) is the transfer function of the engineering fastest integrator, s is the Laplace operator, n is the order of the engineering fastest integrator, and T EFI is the time constant of the engineering fastest integrator.

[0039] Preferably, the transfer function of the negative differential accelerator is:

[0040]

[0041] where T INd is the differential time constant of the input differentiator, s is the Laplace operator, I(t) is the output signal of the accelerator, T I is the integral time constant of the accelerator, T D is the differential time constant of the negative differentiator, and PV IN (t) is the steam temperature control signal of the negative differential accelerator.

[0042] Compared with the prior art, the present application has at least the following beneficial effects:

[0043] By using the input differentiator, the steam temperature control signal is signal-converted to obtain a first differential output signal; by using the positive feedback accelerator, the first differential output signal is accelerated to obtain a steam temperature acceleration control signal; by using the negative differentiator, the acceleration signal is signal-converted to obtain a second differential output signal; by using the negative output controller, the negative acceleration signal in the second differential output signal is extracted; by using the addition link, the first differential output signal and the negative acceleration signal are added to obtain a steam temperature acceleration control signal. The present application performs negative acceleration on the process signal through the negative differential accelerator, so that the negative signal with a downward trend in the process signal is output in advance, thereby performing negative over-temperature control in advance, reducing control lag, and further being able to solve the negative over-temperature problem existing in the secondary superheated steam temperature control system, and enhancing the control effect.

[0044] In addition, the present application performs conditional limiting on the output of the accelerator through a limiter, and cooperates with the negative input controller and the differentiator to solve the current control lag problem and output signal control in advance, so as to improve the control effect of the secondary superheated steam temperature of the secondary superheated steam temperature control system of the thermal power unit and suppress negative over-temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic flow chart of the acceleration method of the steam temperature control signal shown in the embodiment of the present application;

[0046] Figure 2 It is a schematic structural diagram of the negative differential accelerator shown in an embodiment of the present application;

[0047] Figure 3 It is a schematic structural diagram of the negative differential accelerator shown in another embodiment of the present application;

[0048] Figure 4 It is a schematic extraction result diagram of the negative differential accelerator shown in the embodiment of the present application;

[0049] Figure 5 It is a schematic structural diagram of the secondary superheated steam temperature control system shown in the embodiment of the present application;

[0050] Figure 6 It is a schematic control result diagram of the secondary superheated steam temperature control system shown in the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts belong to the scope of protection of the present application.

[0052] It should be understood that the step numbers used in the text are only for convenient description and do not limit the order of execution of the steps.

[0053] It should be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of the present application and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0054] The terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0055] The term "and / or" refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0056] Any process or method description described in the present application can be understood to represent a module, segment or part of code including one or more executable instructions for implementing a specific logical function or process. The scope of the preferred embodiments of the present application includes additional implementations, where the functions can be executed in a manner that is not shown or discussed, including in a substantially simultaneous manner or in a reverse order according to the functions involved, which should be understood by those skilled in the technical field to which the embodiments of the present application belong.

[0057] The logic and / or steps described in the present application, for example, can be considered as a predefined list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus or device), or in combination with these instruction execution systems, apparatus or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate or transport a program for use by or in combination with an instruction execution system, apparatus or device.

[0058] Please refer to Figure 1 ,Figure 1 The flowchart of an acceleration method for steam temperature control signals provided by an embodiment of the present application. The acceleration method for steam temperature control signals in the embodiment of the present application can be applied to a negative differential accelerator, and the negative differential accelerator can be integrated into a computer device, which includes but is not limited to devices such as smartphones, laptops, tablets, desktop computers, physical servers, and cloud servers.

[0059] Optionally, as Figure 2 shown in the structural schematic diagram of the negative differential accelerator, the negative differential accelerator (Negative differential signal accelerator, NDSA) includes an input differentiator 21, a positive feedback accelerator 22, a negative differentiator 23, a negative output controller 24, and an addition link 25.

[0060] As Figure 1 shown, the method of this embodiment includes steps S101 to S105, which are described in detail as follows:

[0061] Step S101: Use the input differentiator to perform signal conversion on the steam temperature control signal to obtain a first differential output signal.

[0062] In this step, as Figure 2 shown, the input differentiator 21, the positive feedback accelerator 22, the negative differentiator 23, the negative output controller 24, and the addition link 25 are connected in sequence. The steam temperature control signal is input into the input differentiator so that the input differentiator extracts the negative signal in the steam temperature control signal, thereby facilitating the subsequent extraction of the negative signal affecting the negative over-temperature in advance, and further enabling the control system to observe the steam temperature control signal in advance and perform signal control to reduce the control lag problem.

[0063] Optionally, the steam temperature control signal is a process signal, and the process signal is the deviation signal between the superheated steam temperature signal of the secondary superheated steam temperature control system and the superheated steam temperature set signal to suppress the negative over-temperature of the secondary superheated steam temperature control system.

[0064] In some embodiments, step S101 includes:

[0065] Use the input differentiator to convert the downward trend in the steam temperature control signal into a negative signal, and the negative signal serves as the first differential output signal input to the positive feedback accelerator. The input differentiator is:

[0066]

[0067] where IND(s) is the transfer function of the input differentiator, T INDis the differential time constant of the input differentiator, and s is the Laplace operator.

[0068] In this embodiment, the steam temperature control signal itself has a differential signal. The function of the input differentiator is to extract the negative signal with a downward trend in the steam temperature control signal to effectively control negative overheating.

[0069] Step S102: Use the positive feedback accelerator to accelerate the first differential output signal to obtain an acceleration signal.

[0070] In this step, the positive feedback accelerator accelerates the negative signal so that the negative signal is output in advance, thereby achieving advance control and reducing the control lag of the secondary superheated steam temperature system caused by negative overheating problems.

[0071] In some embodiments, as Figure 3 shown, the positive feedback accelerator 22 includes a positive feedback link 221, an accelerator 222, and a limiter 223. Using the positive feedback accelerator 22 to accelerate the first differential output signal to obtain a steam temperature acceleration control signal, including:

[0072] Use the positive feedback link 221 to control the accelerator 222 to accelerate;

[0073] Use the accelerator 222 to accelerate the negative signal in the first differential output signal to obtain a negative acceleration signal;

[0074] Use the limiter 223 to limit the negative acceleration signal output by the accelerator 222 to obtain the steam temperature acceleration control signal.

[0075] In this embodiment, the output end of the positive feedback link 221 is connected to the input end of the negative differentiator 23 and the input end of the accelerator 222 to input the process signal into the accelerator 222 for acceleration. The accelerator 222 outputs the accelerated signal to the positive feedback link 221. When the positive feedback link 221 confirms that the process signal acceleration is completed, the signal accelerated by the accelerator 222 is output to the negative differentiator 23.

[0076] Among them, the accelerator 222 is connected to the limiter 223 to conditionally limit the signal output by the accelerator 222 when the accelerator 222 accelerates the process signal, and directly limit the negative signal with a low limit value in the first differential signal output by the input differentiator.

[0077] As Figure 3As shown, the first differential output signal output by the input differentiator is input into the positive feedback loop, and the positive feedback loop controls the accelerator to accelerate. Among them, the negative signal in the first differential output signal is limited by a limiter so that the accelerator accelerates the negative signal. The negative acceleration signal output by the accelerator is conditionally limited by the limiter and fed back to the positive feedback loop. When the positive feedback loop confirms that the acceleration process of the accelerator is over, the acceleration signal is input into the negative differentiator to extract the differential signal in the acceleration signal by using the negative differentiator, and the second differential output signal is obtained; finally, the second differential output signal is input into the negative output controller to extract the negative acceleration signal in the second differential output signal, realizing negative acceleration.

[0078] Optionally, the accelerator is:

[0079]

[0080] The limiter is:

[0081]

[0082] Where I(s) is the transfer function of the accelerator, s is the Laplace operator, and T I is the integral time constant of the accelerator, I(t) is the output signal of the accelerator, and IND(t) is the output signal of the input differentiator.

[0083] Step S103: Use the negative differentiator to perform signal conversion on the acceleration signal to obtain the second differential output signal.

[0084] In this step, the negative differentiator extracts the differential signal of the acceleration signal so that the negative output controller performs negative output.

[0085] Optionally, the negative differentiator is:

[0086]

[0087] Where D(s) is the transfer function of the negative differentiator, s is the Laplace operator, and T D is the differential time constant of the negative differentiator.

[0088] Step S104: Use the negative output controller to extract the negative acceleration signal in the second differential output signal.

[0089] In this step, the negative output controller is:

[0090]

[0091] Wherein, NOC(t) is the output signal of the negative output controller, and D(t) is the output signal of the negative differentiator.

[0092] Step S105: Use the addition unit to perform an addition operation on the first differential output signal and the negative acceleration signal to obtain a steam temperature acceleration control signal.

[0093] In this step, the negative acceleration signal corresponding to the downward trend in the steam temperature control signal and the first differential output signal are synthesized through the addition unit to generate a complete steam temperature acceleration control signal, realizing the extraction of the process signal in advance, so that the control system can observe the process signal in advance to enable signal control in advance.

[0094] Optionally, the addition unit is:

[0095] A(t) = IND(t) + NOC(t);

[0096] Wherein, A(t) is the output signal of the addition unit, P(t) is the first differential output signal, and DOC(t) is the output signal of the negative output controller.

[0097] As an example rather than a limitation, the acceleration observation of the steam temperature control signal for the process output signal of a fourth-order inertia process (FOIP) under a unit step input is performed.

[0098] The fourth-order inertia process FOIP is:

[0099]

[0100] In the formula, FOIP(s) is the transfer function of the fourth-order inertia process FOIP, FOIP(s) is the transfer function of FOIP, and T FOIP is the FOIP time constant, with the unit of s.

[0101] At T I = 100 s, T IND = T D = 100 s, T FOIP = 100 s, the FOIP input is a negative unit step signal, and the result of the acceleration observation NDSA output signal of the steam temperature control signal of the FOIP process output signal is obtained, as Figure 4 shown.

[0102] PV FOIP (t) is the process output signal of the fourth-order inertia process FOIP under a negative unit step input, PV IND (t) is the output signal of the input differentiator, PV NDSA(t) is the output signal of the NDSA for accelerating the observation of the steam temperature control signal. It can be seen that the negative output signal of the NDSA significantly leads the negative output signal of the input differentiator IND, achieving the effect of accelerating the observation of the steam temperature control signal.

[0103] Please refer to Figure 5 , this application also provides a structural schematic diagram of a secondary superheated steam temperature control system. As Figure 5 shown, the system includes a controller (Controller, C) and a control process (Controller Process, CP). The controller includes a cascade proportional controller CPC, an engineering fastest integrator EFI, and a Figure 2 or Figure 3 shown negative differential accelerator NDSA;

[0104] The cascade proportional controller is respectively connected to the engineering fastest integrator and the negative differential accelerator. The steam temperature control signal of the cascade proportional controller is a process signal, and the process signal is the deviation signal between the superheated steam temperature signal and the superheated steam temperature setpoint signal of the secondary superheated steam temperature control system;

[0105] The controller is:

[0106] C(s) = K cpc [EFI(s) + NDSA(s)];

[0107] where C(s) is the transfer function of the controller, EFI(s) is the transfer function of the engineering fastest integrator, NDSA(s) is the transfer function of the negative differential accelerator, and K cpc is the gain of the cascade proportional controller.

[0108] Optionally, the transfer function of the engineering fastest integrator is:

[0109]

[0110] where EFPI(s) is the transfer function of the engineering fastest integrator, s is the Laplace operator, n is the order of the engineering fastest integrator, and T EFI is the time constant of the engineering fastest integrator.

[0111] Optionally, the transfer function of the negative differential accelerator is:

[0112]

[0113] where T INd is the differential time constant of the input differentiator, s is the Laplace operator, I(t) is the output signal of the accelerator, and T I is the integral time constant of the accelerator, and T Dis the differential time constant of the negative differentiator, PV IN (t) is the steam temperature control signal of the negative differential accelerator.

[0114] By way of example and not limitation, applying the controller C to the secondary superheated steam temperature control system of a 1000MW ultra-supercritical thermal power unit in a certain power plant, the control results obtained are as Figure 6 shown. Figure 6 As shown, the process steam temperature control signal acceleration observer NDSA is added after 11:00. Before adding NDSA, the maximum negative deviation of the secondary superheated steam temperature relative to the given value of the secondary superheated steam temperature is 11.6°C; after adding PFAD, the maximum negative deviation of the secondary superheated steam temperature is 4.1°C. It can be seen that NDSA has a good effect on suppressing the negative deviation of the secondary superheated steam temperature.

[0115] In several embodiments provided in the present application, it can be understood that each block in the flowchart or block diagram may represent a module, a program segment, or a part of code, and the module, the program segment, or the part of code includes one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved.

[0116] If the above functions are implemented in the form of software function modules and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a terminal device to execute all or part of the steps of the methods described in various embodiments of the present application. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, etc., which can store program codes.

[0117] The specific embodiments described above have further elaborated on the purpose, technical solution, and beneficial effects of the present application. It should be understood that the above description is only specific embodiments of the present application and is not used to limit the protection scope of the present application. In particular, it is pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for accelerating a steam temperature control signal, characterized in that, Applied to a negative differential accelerator, the negative differential accelerator includes an input differentiator, a positive feedback accelerator, a negative differentiator, a negative output controller, and an addition unit; Using the input differentiator, perform signal conversion on the steam temperature control signal to obtain a first differential output signal; Using the positive feedback accelerator, accelerate the first differential output signal to obtain an acceleration signal; Using the negative differentiator, perform signal conversion on the acceleration signal to obtain a second differential output signal; Using the negative output controller, extract the negative acceleration signal from the second differential output signal; Using the addition unit, perform an addition operation on the first differential output signal and the negative acceleration signal to obtain a steam temperature acceleration control signal.

2. The acceleration method of the steam temperature control signal according to claim 1, characterized in that, The steam temperature control signal is the deviation signal between the superheated steam temperature signal of the secondary superheated steam temperature control system and the superheated steam temperature setpoint signal.

3. The acceleration method of the steam temperature control signal according to claim 1, characterized in that, The using the input differentiator to perform signal conversion on the steam temperature control signal to obtain a first differential output signal includes: Using the input differentiator, convert the downward trend in the steam temperature control signal into a negative signal, and the negative signal serves as the first differential output signal input to the positive feedback accelerator. The input differentiator is: where IND(s) is the transfer function of the input differentiator, T IND is the differentiation time constant of the input differentiator, and s is the Laplace operator.

4. The acceleration method of the steam temperature control signal according to claim 1, characterized in that The positive feedback accelerator includes a positive feedback unit, an accelerator, and a limiter. Using the positive feedback accelerator to accelerate the first differential output signal to obtain an acceleration signal includes: Using the positive feedback unit to control the accelerator to accelerate; Using the accelerator to accelerate the negative signal in the first differential output signal to obtain a negative acceleration signal; Using the limiter to limit the negative acceleration signal output by the accelerator to obtain the acceleration signal.

5. The acceleration method of the steam temperature control signal according to claim 4, characterized in that The accelerator is: The limiter is: where I(s) is the transfer function of the accelerator, s is the Laplace operator, T I is the integration time constant of the accelerator, I(t) is the output signal of the accelerator, and IND(t) is the output signal of the input differentiator.

6. The acceleration method of the steam temperature control signal according to claim 1, characterized in that, The negative differentiator is: where D(s) is the transfer function of the negative differentiator, s is the Laplace operator, and T D is the differentiation time constant of the negative differentiator.

7. The acceleration method of the steam temperature control signal according to claim 1, characterized in that, The negative output controller is: Wherein, NOC(t) is the output signal of the negative output controller, and D(t) is the output signal of the negative differentiator.

8. A secondary superheated steam temperature control system, characterized in that, Including a controller, the controller includes a cascade proportional controller, an engineering fastest integrator, and a negative differential accelerator as described in any one of claims 1 to 7; The cascade proportional controller is respectively connected to the engineering fastest integrator and the negative differential accelerator. The steam temperature control signal of the cascade proportional controller is a process signal, and the process signal is the deviation signal between the superheated steam temperature signal of the secondary superheated steam temperature control system and the superheated steam temperature setpoint signal; The controller is: C(s) = K cpc [EFI(s) + NDSA(s)]; Among them, C(s) is the transfer function of the controller, EFI(s) is the transfer function of the engineering fastest integrator, NDSA(s) is the transfer function of the negative differential accelerator, and K cpc is the gain of the cascade proportional controller, and s is the Laplace operator.

9. The secondary superheated steam temperature control system according to claim 8, characterized in that The transfer function of the engineering fastest integrator is: Among them, EFPI(s) is the transfer function of the engineering fastest integrator, s is the Laplace operator, n is the order of the engineering fastest integrator, and T EFI is the time constant of the working fastest integrator.

10. The secondary superheated steam temperature control system according to claim 8, characterized in that, The transfer function of the negative differential accelerator is: Among them, T IND is the differential time constant of the input differentiator, s is the Laplace operator, I(t) is the output signal of the accelerator, T I is the integral time constant of the accelerator, T D is the differential time constant of the negative differentiator, PV IN (t) is the steam temperature control signal of the negative differential accelerator.

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