Improved active-disturbance-rejection control method and device for thermal power generating unit under large-range variable load

Abstract

The invention provides an improved active-disturbance-rejection control method and device for a thermal power generating unit under a large-range variable load, and relates to the technical field of power grid control. The control method provided by the invention is used for a direct energy balance coordination control system of a thermal power generating unit, a main steam pressure loop adopts improved active disturbance rejection control (MADRC), a load loop adopts conventional active disturbance rejection control (ADRC), and in addition, the feed-forward design of the main steam pressure loop adopts variable proportion gain and definite differential gain to carry out dynamic change. A parameter setting process which is easy to implement and high in engineering performance is provided for improved active disturbance rejection control (MADRC). According to the control method, the tracking performance of the main steam pressure loop can be improved, in addition, under different loads, the control method can remarkably improve the anti-interference capacity of the coordination control system, and the control method has very high engineering application value.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid control, and in particular to an improved self-disturbance rejection control method and device for a thermal power unit under a wide range of variable loads. Background Art

[0002] Renewable energy sources such as wind power and photovoltaic power are integrated into the power grid on a large scale. Due to their randomness, uncertainty and transient nature, renewable energy is less able to meet the electricity needs of users. In order to ensure the quality of power supply and the stability of the power grid, thermal power units have taken on the task of peak load regulation, and realize the consumption of new energy by quickly raising and lowering the load while ensuring the quality of power supply. However, the large-scale variable load of thermal power units causes significant changes in the characteristics of the units, which brings great challenges to the design of control strategies.

[0003] Considering the difficulty of actual engineering application, the control strategy of the coordinated control system of thermal power units should have strong robustness to adapt to a wide range of variable load conditions, strong anti-interference ability, easy-to-set parameters and easy on-site engineering implementation. However, the conventional coordinated control system of thermal power units has weakened anti-interference ability under a wide range of variable load conditions, and the set parameters are difficult to meet the control requirements of a wide range of variable loads. Advanced control methods, such as sliding mode control, model predictive control and fuzzy control, have certain difficulties in actual application and often fail to achieve good control effects. Summary of the invention

[0004] Purpose of the invention: In view of the problem that large-scale load variation of thermal power units causes significant changes in the characteristics of the units and the anti-interference ability of conventional coordinated control deteriorates, an improved self-anti-interference control method and device for thermal power units under large-scale load variation are proposed, aiming to improve the tracking performance of the main steam pressure loop.

[0005] In a first aspect of the present invention, an improved active disturbance rejection control method for a thermal power unit under a wide range of load variations is provided, and the steps are as follows:

[0006] Based on the main steam pressure loop and / or load loop of the target thermal power unit, a first-order process model is constructed;

[0007] Based on the first-order process model, combined with the feedforward based on dynamic gain, an active disturbance rejection control model with adaptive input compensation structure is obtained;

[0008] Setting predetermined parameters in the active disturbance rejection control model;

[0009] The active disturbance rejection control model with adjusted parameters is used to control the target thermal power unit under a wide range of variable loads.

[0010] In a further embodiment, a first-order process model is constructed based on the main steam pressure loop and / or load loop of the target thermal power unit. The expression of the first-order process model is as follows:

[0011]

[0012] In the formula, b is the process gain coefficient; b0 is the initial value of the process gain coefficient; u represents the control input; is the first-order derivative of the process output; g(·) is a function that includes the time-varying, higher-order, perturbative and nonlinear characteristics of the process; f(·) represents the total disturbance of the first-order process.

[0013] In a further embodiment, the total disturbance f(·) of the first-order process is calculated by ESO, and the ESO calculation expression is as follows:

[0014]

[0015] Where z1 and z2 are the estimated values ​​of y and f respectively; β1 and β2 are ESO gains;

[0016]

[0017] Where ξ is an adjustable parameter, ξ∈[0.1,10].

[0018] In a further embodiment, the control input u is adjusted to eliminate the total disturbance f(·); the adjusted control input u is expressed as follows:

[0019]

[0020] In the formula, k p is the control law gain, r is the controlled variable setting value, k p are the parameters that need to be adjusted.

[0021] In a further embodiment, based on the first-order process model, combined with a dynamic gain-based feedforward, an auto-disturbance rejection control model with an adaptive input compensation structure is obtained;

[0022] The feedforward expression based on dynamic gain is as follows:

[0023]

[0024] in and is the parameter to be adjusted, r Ne and are the power setting value and the first-order derivative of the setting value respectively;

[0025] The expression of the active disturbance rejection control model of the adaptive input compensation structure is as follows:

[0026]

[0027] In the formula, s is the pull operator, T p is the compensation coefficient that changes with load, T p =q(Ne), q(Ne) is T as Ne changes p Variation function.

[0028] In a further embodiment, the predetermined parameters in the active disturbance rejection control model are adjusted, specifically including:

[0029] S1. Determine T p The values ​​under the first percentage, second percentage and third percentage load conditions are obtained by linear interpolation function to realize T under different loads. p Value switch;

[0030] S2, determine the b0 value, b0 is as close as possible to the process gain coefficient b;

[0031] S3, select k less than the preset value p and let ξ=1,ω o Increase gradually from small to large until the control effect changes within the predetermined range;

[0032] S4, gradually increase k p value until the expected control effect is achieved, and further adjust ξ to improve the anti-interference ability of the closed-loop system;

[0033] S5. If the system output oscillates, increase b0 step by step and repeat steps S2 to S4.

[0034] According to a second aspect of the present invention, an improved anti-disturbance control device for a thermal power unit is provided. The device comprises a first construction unit, a second construction unit, a parameter adjustment unit, and a control unit.

[0035] The first construction unit is used to construct a first-order process model based on a main steam pressure loop and / or a load loop of a target thermal power unit.

[0036] The second construction unit is used to obtain an active disturbance rejection control model with an adaptive input compensation structure based on the first-order process model and in combination with a dynamic gain-based feedforward.

[0037] The parameter adjustment unit is used to adjust the predetermined parameters in the active disturbance rejection control model.

[0038] The control unit uses the ADRC model with adjusted parameters to control the target thermal power unit under a wide range of variable loads.

[0039] According to a third aspect of the present invention, an electronic device is proposed, comprising a processor and a memory storing computer program instructions; when the processor executes the computer program instructions, the improved self-anti-disturbance control method for thermal power units under a wide range of variable loads as described in the first aspect and its further embodiments is implemented.

[0040] According to a fourth aspect of the present invention, a computer-readable storage medium is provided, in which at least one executable instruction is stored. When the executable instruction is executed on an electronic device, the electronic device executes the improved self-disturbance rejection control method for thermal power units under a wide range of variable loads as described in the first aspect and its further embodiments.

[0041] Beneficial effects: The present invention proposes an improved self-disturbance rejection control method for thermal power units under a wide range of variable loads. The method is used for the direct energy balance control structure of thermal power units, wherein the main steam pressure loop and the load loop adopt improved self-disturbance rejection control and conventional self-disturbance rejection control, respectively. Further, the present invention provides a parameter setting method for the improved self-disturbance rejection control. The control method of the present invention can improve the tracking performance of the main steam pressure loop. In addition, under different loads, the control method can significantly improve the anti-disturbance capability of the coordinated control system, and has a strong engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the DEB control structure of the thermal power unit based on MADRC in the embodiment.

[0043] Figure 2 The active disturbance rejection MADRC control structure in the embodiment is improved. DETAILED DESCRIPTION

[0044] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described.

[0045] like Figure 1 As shown, an embodiment of the present invention provides an improved self-disturbance rejection control method for a thermal power unit under a wide range of variable loads.

[0046] The overall control structure is shown in the figure Figure 1 As shown, where r pt is the pressure setting value, r Q′m is the boiler energy demand value, v t is the turbine valve command, M is the fuel quantity command, Ne is the actual power, p b is the separator pressure, C b1is the heat storage coefficient, p1 is the pressure after the regulating stage, p t is the main steam pressure, Q′ m is the calculated energy signal.

[0047] This control method is used for the direct energy balance coordinated control system of thermal power units, in which the main steam pressure loop adopts improved active disturbance rejection control (MADRC) combined with dynamic gain-based feedforward; a parameter setting process that is easy to implement and has strong engineering properties is proposed for the improved active disturbance rejection control (MADRC); the load loop adopts conventional active disturbance rejection control (ADRC).

[0048] like Figure 2 As shown in the figure, the structure of the improved active disturbance rejection control (MADRC) is described as follows:

[0049] For the main steam pressure loop or load loop of the unit, its model can be organized into a first-order process:

[0050]

[0051] Among them, t, b, and ω are the time-varying time, process gain coefficient, second-order derivative of process output and external disturbance respectively, u represents the control input, y is the process output, is the first-order derivative of the process output. g(·) is a function that includes time-varying, high-order, perturbation and nonlinearity of the process. Considering that the exact value of the process gain coefficient cannot be accurately known, it may even change with load changes. Define b0 as the estimated value of b, formula (1) can be equivalent to:

[0052]

[0053] Among them, f(·)=g(·)+(b-b0)u is called the "total disturbance" of the process, which is also an expansion state of the process. f(·) can be estimated by ESO, and the ESO calculation expression is as follows:

[0054]

[0055] Where β1 and β2 are ESO gains. When β1 and β2 are properly adjusted, z1 and z2 are the estimated values ​​of y and f, respectively, which can track y and f relatively well.

[0056] In order to better adjust the parameters, β1 and β2 can be adjusted by the ESO bandwidth ω o Simplify.

[0057] In order to increase the flexibility of parameter setting, formula (4) adds adjustable parameters:

[0058]

[0059] ξ is an adjustable parameter, and ξ∈[0.1,10] is generally recommended.

[0060] The estimated total disturbance f(·) is eliminated by the control law:

[0061]

[0062] where k p is the control law gain, r is the controlled variable setting value, k p The above is the control structure of ADRC. At this time, the ADRC parameters that need to be adjusted include b0, ω o , ξ and k p .

[0063] Since the main steam pressure loop is a typical large inertia process, the asynchrony of the ESO input y and u will cause the ESO bandwidth ω o The estimation accuracy is low due to the limited y and u. In order to improve the synchronization of y and u, a modified active disturbance rejection control (MADRC) with adaptive input compensation structure is proposed.

[0064] definition:

[0065] is the compensation structure of MADRC. s is the pull operator, T p is the compensation factor that changes with load:

[0066] T p =q(Ne) (8)

[0067] Where q(Ne) is T as Ne changes p Variation function.

[0068] The ESO of MADRC is converted into:

[0069]

[0070] where u cp The compensation structure G cp (s,T p ) output. The control law of MADRC is consistent with formula (6).

[0071] The gain-based feedforward calculation expression is:

[0072]

[0073] in It is the setting parameter related to the actual power; For fixed parameters that need to be adjusted, set it to 50; r Ne and are the power setting value and the first-order derivative of the setting value respectively. The relationship with the actual transmission power is shown in Table 1:

[0074] Table 1: Relationship with actual power

[0075]

[0076] Step 1 First determine T under different loads p Value. p The values ​​of T under 37.95%, 77.97% and 94.18% load conditions are 145, 120 and 100 respectively, and the linear interpolation function is used to realize T under different loads. p Value switch;

[0077] Step 2: Determine the value of b0, which should be as close to the process gain factor b as possible;

[0078] Step 3 Select a smaller k p and let ξ=1,ω o Increase gradually from small to large until the control quality of the control effect does not change significantly;

[0079] Step 4: Gradually increase k p value until satisfactory control quality is achieved, and further adjustment can be made to improve the anti-interference ability of the closed-loop system;

[0080] Step 5: If the system output oscillates, increase b0 appropriately and repeat Step 2-Step 4.

[0081] Through Step 1-Step 5, the MADRC parameters of the main steam pressure loop of the thermal power unit are obtained as b0=0.5, ω o =1.89, ξ = 1 and k p =4.7.

[0082] Similarly, the conventional ADRC parameters of the load loop are b0 = 1.2, ω o =2.2, ξ = 1 and k p =6.

[0083] In addition, an embodiment of the present invention also discloses an improved anti-disturbance control device for a thermal power unit, which includes a first construction unit, a second construction unit, a parameter adjustment unit, and a control unit. The first construction unit is used to construct a first-order process model based on the main steam pressure loop and / or load loop of the target thermal power unit. The second construction unit is used to obtain an anti-disturbance control model with an adaptive input compensation structure based on the first-order process model and combined with a dynamic gain-based feedforward. The parameter adjustment unit is used to adjust predetermined parameters in the anti-disturbance control model. The control unit uses the anti-disturbance control model after parameter adjustment to complete the control of the target thermal power unit under a wide range of variable loads.

[0084] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0085] It should be noted that the improved self-disturbance rejection control method for thermal power units disclosed in the above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination in the actual application process. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0086] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. An improved active disturbance rejection control method for a thermal power unit under a wide range of variable loads, characterized in that: The steps include: Based on the main steam pressure loop and / or load loop of the target thermal power unit, a first-order process model is constructed; Based on the first-order process model, combined with the feedforward based on dynamic gain, an active disturbance rejection control model with adaptive input compensation structure is obtained; Setting predetermined parameters in the active disturbance rejection control model; The active disturbance rejection control model with adjusted parameters is used to control the target thermal power unit under a wide range of variable loads.

2. The improved anti-disturbance control method for thermal power units under large-scale variable load according to claim 1 is characterized in that: Based on the main steam pressure loop and / or load loop of the target thermal power unit, a first-order process model is constructed. The expression of the first-order process model is as follows: In the formula, b is the process gain coefficient; b0 is the initial value of the process gain coefficient; u represents the control input; is the first-order derivative of the process output; g(·) is a function that includes the time-varying, higher-order, perturbative and nonlinear characteristics of the process; f(·) represents the total disturbance of the first-order process.

3. The improved auto-disturbance rejection control method for thermal power units under large-scale variable load according to claim 2 is characterized in that: The total disturbance f(·) of the first-order process is calculated by ESO, and the ESO calculation expression is as follows: Where z1 and z2 are the estimated values ​​of y and f respectively; β11 and β2 are ESO gains; Where ξ is an adjustable parameter, ξ∈[0.1,10].

4. The improved auto-disturbance rejection control method for thermal power units under large-scale variable load according to claim 2 is characterized in that: The method further includes: adjusting the control input u to eliminate the total disturbance f(·); the expression of the adjusted control input u is as follows: In the formula, k p is the control law gain, r is the controlled variable setting value, k p are the parameters that need to be adjusted.

5. The improved active disturbance rejection control method for thermal power units under large-scale variable load according to claim 3 is characterized in that: Based on the first-order process model, combined with the feedforward based on dynamic gain, an active disturbance rejection control model with adaptive input compensation structure is obtained; The feedforward expression based on dynamic gain is as follows: in and is the parameter to be adjusted, r Ne and are the power setting value and the first-order derivative of the setting value respectively; The expression of the active disturbance rejection control model of the adaptive input compensation structure is as follows: In the formula, s is the pull operator, T p is the compensation coefficient that changes with load, T p =q(Ne), q(Ne) is T as Ne changes p Change function.

6. The improved auto-disturbance rejection control method for thermal power units under large-scale variable load according to claim 5 is characterized in that: The predetermined parameters in the active disturbance rejection control model are adjusted, specifically including: S1. Determine T p The values ​​under the first percentage, second percentage and third percentage load conditions are obtained by linear interpolation function to realize T under different loads. p Value switch; S2, determining the value of b0 so that the difference between b0 and the process gain coefficient b is within a predetermined range; S3, select k less than the preset value p and let ξ=1,ω o Increase gradually from small to large until the control effect changes within the predetermined range; S4, gradually increase k p value until the expected control effect is achieved, and further adjust ξ to improve the anti-interference ability of the closed-loop system; S5. If the system output oscillates, increase b0 step by step and repeat steps S2 to S4.

7. An improved anti-disturbance control device for a thermal power unit, characterized in that: include: A first construction unit is used to construct a first-order process model based on a main steam pressure loop and / or a load loop of a target thermal power unit; A second construction unit is used to obtain an active disturbance rejection control model of an adaptive input compensation structure based on the first-order process model and in combination with a dynamic gain-based feedforward; A parameter adjustment unit, used for adjusting predetermined parameters in the active disturbance rejection control model; The control unit uses the active disturbance rejection control model after parameter adjustment to complete the control of the target thermal power unit under a wide range of variable loads.

8. An electronic device, characterized in that: The device comprises: a processor and a memory storing computer program instructions; when the processor executes the computer program instructions, the improved self-disturbance rejection control method for thermal power units under a wide range of variable loads as described in any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that: The storage medium stores at least one executable instruction, and when the executable instruction is executed on the electronic device, the electronic device executes the improved self-disturbance rejection control method for thermal power units under a wide range of variable loads as described in any one of claims 1 to 6.

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