CN111413865A - Disturbance compensation single-loop superheated steam temperature active disturbance rejection control method - Google Patents

Abstract

The invention provides a disturbance-compensated single-loop superheated steam temperature automatic disturbance rejection control method, which belongs to the technical field of automatic control. This method belongs to a weak model control strategy, and does not require the precise mathematical description of the thermal power unit superheated steam temperature object; the reduced-order first-order expansion state observer algorithm is used to compensate the value of the previous calculation step of the desuperheating water object, and the compensation of the current calculation step is obtained. Input the output value of the current step sequence of the superheated steam temperature system and the compensation value of the current step sequence into the expansion state observer for calculation, and obtain the tracking value of the output value of the superheated steam temperature system and the tracking value of the total disturbance, and then pass The input values of the last two calculation steps of the superheated steam temperature system are obtained by calculation, so that the system can adjust the opening of the desuperheating water valve in real time according to the calculation results. Compared with the traditional superheated steam temperature cascade control, the present invention simplifies the structure of the control system, and simultaneously can take into account the tracking and anti-disturbance capabilities of the closed-loop system, and has better control quality.

Description

A Disturbance Compensation Single-loop Superheated Steam Temperature Active Disturbance Rejection Control Method

technical field

The invention belongs to the technical field of automatic control, and in particular relates to a single-loop superheated steam temperature automatic disturbance rejection control method with disturbance compensation.

Background technique

At present, the control of large-scale industrial production processes such as chemical process and thermal process is still dominated by proportional-integral (PI) control and proportional-integral-derivative (PID) control. This is because PI and PID are simple and easy to implement, and there are many parameter tuning methods. However, with the increasing control requirements in industrial processes, it is difficult for traditional PI or PID controllers to obtain satisfactory control results. Active Disturbance Rejection Control (ADRC) technology was proposed by researcher Han Jingqing. Its core idea is to integrate modeling errors, external disturbances and high-order dynamics of objects into the extended state of the system, and use the Extended State Observer (Extended State Observer) State Observer, ESO) to estimate and compensate the expansion state. Today, ADRC has been applied on-site in furnace negative pressure, secondary air and other systems, laying the foundation for its wide application in industrial processes.

For the superheated steam temperature system in thermal power units, the cascade control strategy is often used to control the outlet temperature of the superheater. This is mainly because the superheated steam temperature is a typical object with large inertia and large delay, and traditional simple control is used. The single-loop control strategy of the controller cannot obtain a better control effect. In the superheated steam temperature cascade system, the PID/PI controller is commonly used in the outer loop, and the PI controller is commonly used in the inner loop. The output of the outer loop controller is used as the set value of the inner loop, which makes the system have a certain adaptive ability. The cascade control system is suitable for objects that can be segmented and the intermediate signal can be measured. However, the structure of the cascade control system is more complicated, the tuning is more complicated, and it is more difficult to realize in the decentralized control system than the single-loop control. In addition, the cascade control with the PI controller as the inner loop controller, which is widely used in the industry, is prone to large fluctuations when overcoming the secondary disturbance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the shortcomings of the current superheated steam temperature cascade control system with complex structure, difficult parameter setting and overcoming the large fluctuation caused by secondary disturbance, and propose a single-loop superheated steam temperature improvement reactive reactance based on disturbance compensation. The disturbance control method is designed to simplify the structure of the superheated steam temperature control system, and has a good reference tracking and anti-disturbance capability, which provides a good support for further promoting the field application of ADRC in the industrial process control with large inertia and large delay.

The technical scheme of the present invention is as follows:

A disturbance-compensated single-loop superheated steam temperature first-order active disturbance rejection control method, characterized in that it includes the following steps:

1) Define the transfer function relationship between the steam temperature at the inlet of the superheater and the opening of the desuperheating water valve as the secondary object, and the transfer function relationship between the steam temperature at the outlet of the superheater and the steam temperature at the inlet of the superheater as the main object; take the superheated steam temperature system The secondary object and the main object in are described by high-order inertial links respectively, and their mathematical expressions are as follows:

Among them, Y ₁ (s) is the inlet temperature of the superheater, Y ₂ (s) is the outlet temperature of the superheater, U(s) is the opening of the desuperheating water valve, s represents the differential operator, and K ₁ and K ₂ represent the auxiliary objects respectively. With the gain coefficient of the main object, T ₁ and T ₂ represent the time constants of the sub-object and the main object, respectively, and n ₁ and n ₂ represent the orders of the sub-object and the main object, respectively;

2) Use the reduced-order first-order expansion state observer algorithm to compensate the desuperheating water valve opening u(k-1) of the previous calculation step, and the input of the compensation algorithm is the desuperheating water valve opening u of the previous calculation step. (k-1) and the superheater inlet steam temperature y ₁ (k-1), the output is the compensation value u _f (k) of the current step;

The specific mathematical form is as follows:

Among them, k represents the calculation step sequence, h represents the sampling interval time, z ₃ (k-1) and z ₃ (k) respectively represent the intermediate variable values in the compensation algorithm of the previous calculation step sequence and the current calculation step sequence; β ₃ and b ₁ is the adjustable parameter of the compensation link, where β ₃ >0, b ₁ <0;

3) The current calculation step value y ₂ (k) of the superheated steam temperature and the compensation value u _f (k) of the current step obtained by the compensation algorithm are used for real-time estimation and compensation calculation through the expansion state observation algorithm, and the superheated steam temperature is obtained. The tracking value z ₁ (k+1) of one calculation step value y ₂ (k+1) and the observed value z ₂ (k+1) of the next calculation step with the total disturbance:

In the calculation expression, β ₁ , β ₂ and b ₀ are adjustable parameters of the controller, where β ₁ >0, β ₂ >0, and b ₀ <0;

4) Use the following formula to obtain the valve opening value u(k+2) of the next two calculation steps:

Among them, k _p is the adjustable parameter of the controller, and r(k+1) is the output set value of the next calculation step;

5) Update the input value of the last two calculation steps of the superheated steam temperature system to u(k+2), and adjust the opening of the desuperheating water valve to the value of u(k+2), so that the output value of the superheated steam temperature system is track its setpoint.

A disturbance-compensated single-loop superheated steam temperature second-order active disturbance rejection control method provided by the present invention is characterized by comprising the following steps:

1) Define the transfer function relationship between the steam temperature at the inlet of the superheater and the opening of the desuperheating water valve as the secondary object, and the transfer function relationship between the steam temperature at the outlet of the superheater and the steam temperature at the inlet of the superheater as the main object; take the superheated steam temperature system The secondary object and the main object in are described by high-order inertial links respectively, and the mathematical expression is as follows:

Among them, Y ₁ (s) is the inlet temperature of the superheater, Y ₂ (s) is the outlet temperature of the superheater, U(s) is the opening of the desuperheating water valve, s is the differential operator, and K ₁ and K ₂ are the sub-object and The gain coefficient of the main object, T ₁ and T ₂ represent the time constants of the sub-object and the main object, respectively, and n ₁ and n ₂ respectively represent the orders of the sub-object and the main object;

2) Use the reduced-order first-order expansion state observer algorithm to compensate the desuperheating water valve opening u(k-1) of the previous calculation step, and the input of the compensation algorithm is the desuperheating water valve opening u of the previous calculation step. (k-1) and the superheater inlet steam temperature y ₁ (k-1), the output is the compensation value u _f (k) of the current step;

The specific mathematical form is as follows:

Among them, z ₄ (k-1) and z ₄ (k) represent the intermediate variable values in the compensation algorithm of the previous calculation step and the current calculation step, respectively; β ₄ and b ₁ are the adjustable parameters of the compensation link, where β ₄ >0, b ₁ <0;

3) The current calculation step value y ₂ (k) of the superheated steam temperature and the compensation value u _f (k) of the current calculation step obtained by the compensation algorithm are used for real-time estimation and compensation calculation through the expansion state observation algorithm, and the superheated steam temperature is obtained. The tracking value z ₁ (k+1) of the next calculation step value y ₂ (k+1), the tracking value z ₂ (k+1) of its first derivative, and the tracking value of the next calculation step of the total disturbance received Value z ₃ (k+1):

In the calculation expression, β ₁ , β ₂ , β ₃ and b ₀ are adjustable parameters of the controller, where β ₁ >0, β ₂ >0, β ₃ >0, and b ₀ <0;

4) Use the following formula to obtain the valve opening value u(k+2) of the next two calculation steps:

Among them, k _p and k _d are the adjustable parameters of the controller, and r(k+1) is the output set value of the next calculation step;

5) Update the input value of the last two calculation steps of the superheated steam temperature system to u(k+2), and adjust the opening of the desuperheating water valve to the value of u(k+2), so that the output value of the superheated steam temperature system is track its setpoint.

Compared with the prior art, the present invention has the following advantages and outstanding effects: the present invention is directed to the superheated steam temperature system of the thermal power unit, which inherits the simple structure of ADRC in structure, retains the advantages of simple parameter setting, and A better control effect can still be obtained when the mathematical model of the controlled object cannot be accurately described. Compared with the traditional cascade control, the improved single-loop active disturbance rejection control method can simplify the superheated steam temperature control structure. Due to the addition of the compensation link, it can smoothly overcome the system deviation caused by the secondary disturbance. There is a noticeable improvement.

Description of drawings

Figure 1 is a block diagram of a conventional cascade control system.

Figure 2 is a block diagram of a standard first-order ADRC control flow for a class of single-loop objects.

Figure 3 is a block diagram of a standard second-order ADRC control flow for a class of single-loop objects.

FIG. 4 is a block diagram of a disturbance compensation single-loop first-order active disturbance rejection control designed for a superheated steam temperature system according to the present invention.

FIG. 5 is a block diagram of the disturbance compensation single-loop second-order improved active disturbance rejection control designed for the superheated steam temperature system according to the present invention.

6 is a comparison diagram of the single-loop first-order active disturbance rejection control method for disturbance compensation in the simulation calculation of the superheated steam temperature system of the present invention, the traditional PI-PI cascade system, and the standard first-order ADRC-PI cascade system.

7 is a comparison diagram of the reference tracking response of the disturbance compensation single-loop first-order active disturbance rejection control method of the present invention, the traditional PI-PI cascade system and the standard first-order ADRC-PI cascade system in the superheated steam temperature system of the thermal power unit simulator .

FIG. 8 is a comparison diagram of the anti-interference response of the disturbance compensation single-loop first-order active disturbance rejection control method of the present invention, the traditional PI-PI cascade system and the standard first-order ADRC-PI cascade system in the superheated steam temperature system of the thermal power unit simulator .

Detailed ways

A disturbance compensation single-loop superheated steam temperature automatic disturbance rejection control method proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

A disturbance-compensated single-loop ADRR control method for a superheated steam temperature system proposed by the present invention includes first-order and second-order ADRR control methods, which are described as follows.

Fig. 4 is the flow chart of the disturbance compensation single-loop first-order active disturbance rejection control designed for the superheated steam temperature system of the present invention, and its concrete steps are as follows:

1) Define the transfer function relationship between the steam temperature at the inlet of the superheater and the opening of the desuperheating water valve as the secondary object, and the transfer function relationship between the steam temperature at the outlet of the superheater and the steam temperature at the inlet of the superheater as the main object; take the superheated steam temperature system The secondary object and the main object in are described by high-order inertial links respectively, and the mathematical expression is as follows:

Among them, Y ₁ (s) is the inlet temperature of the superheater, Y ₂ (s) is the outlet temperature of the superheater, the opening of the desuperheating water valve is U(s), s represents the differential operator, and K ₁ and K ₂ represent the sub-object and The gain coefficient of the main object, T ₁ and T ₂ respectively represent the time constants of the auxiliary object and the main object, and n ₁ and n ₂ respectively represent the order of the auxiliary object and the main object; the gain coefficient and time constant in the formula can be adjusted according to different The capacity of the unit is determined. In a typical thermal power unit superheated steam temperature system, the gain of the auxiliary object is generally in the range of 0.8 to 6.0, and the time constant is generally in the range of 9 to 30; the gain of the main object is generally in the range of 0.8 to 1.5. , the time constant is generally in the range of 20 to 30;

2) Use the reduced-order first-order expansion state observer algorithm to compensate the desuperheating water valve opening u(k-1) of the previous calculation step, and the input of the compensation algorithm is the desuperheating water valve opening u of the previous calculation step. (k-1) and superheater inlet steam temperature y ₁ (k-1), the output is the compensation value u _f (k) of the current step sequence; where k represents the calculation step sequence, and the Euler method is used in practical applications to calculate the value The calculation of the differential can realize the discrete active disturbance rejection control method. The Euler numerical differential algorithm is as follows:

Where h represents the sampling interval time, and x represents the first derivative of the variable x with respect to time; the specific mathematical form of the compensation algorithm is as follows:

Among them, z ₃ (k-1) and z ₃ (k) represent the intermediate variable values in the compensation algorithm of the previous calculation step and the current calculation step, respectively; β ₃ and b ₁ are the adjustable parameters of the compensation link, where β ₃ >0, b ₁ <0;

3) The current calculation step value y ₂ (k) of the superheated steam temperature and the compensation value u _f (k) of the current step obtained by the compensation algorithm are estimated and compensated in real time through the expansion state observation algorithm, and the superheated steam temperature is obtained. 1. The tracking value z ₁ (k+1) of the calculation step value y ₂ (k+1) and the observed value z ₂ (k+1) of the next calculation step under the total disturbance;

The calculation expressions of z ₁ (k+1) and z ₂ (k+1) are as follows:

In the calculation expression, β ₁ , β ₂ and b ₀ are adjustable parameters of the controller. Wherein, β ₁ >0, β ₂ >0, b ₀ <0;

4) The difference between the superheated steam temperature set value r(k+1) of the next calculation step and the tracking value z ₁ (k+1) of the superheated steam temperature of the next calculation step value y ₂ (k+1) After the value is amplified by k _p times, the observed value z ₂ (k+1) of the total disturbance of the superheated steam temperature system is subtracted, and the obtained result is amplified by 1/b ₀ times and used as the opening value of the desuperheating water valve in the next two calculation steps. u(k+2);

The mathematical formula for the opening value u(k+2) of the desuperheating water valve in the last two calculation steps is as follows:

Among them, k _p is an adjustable parameter of the controller, and the parameter k _p selects an appropriate value according to the control requirements.

5) Update the value of the last two calculation steps for the opening of the desuperheating water valve to u(k+2), and adjust the opening of the desuperheating water valve to the value of u(k+2).

After the opening value of the desuperheating water valve is updated to u(k+2), it is used as the input of the compensation algorithm for the calculation of the next cycle. After u(k+2) is sent to the superheated steam temperature system, the output of the superheated steam temperature system is realized. value adjustment.

According to the above steps, the implementation of the single-loop superheated steam temperature first-order active disturbance rejection control method with disturbance compensation can be carried out.

5 is a block diagram of the disturbance compensation single-loop second-order active disturbance rejection control designed for the superheated steam temperature system of the present invention, which includes the following steps:

1) Define the transfer function relationship between the steam temperature at the inlet of the superheater and the opening of the desuperheating water valve as the secondary object, and the transfer function relationship between the steam temperature at the outlet of the superheater and the steam temperature at the inlet of the superheater as the main object; take the superheated steam temperature system The secondary object and the main object in are described by high-order inertial links respectively, and the mathematical expression is as follows:

Among them, Y ₁ (s) is the inlet temperature of the superheater, Y ₂ (s) is the outlet temperature of the superheater, the opening of the desuperheating water valve is U(s), s represents the differential operator, and K ₁ and K ₂ represent the sub-object and The gain coefficient of the main object, T ₁ and T ₂ respectively represent the time constants of the auxiliary object and the main object, and n ₁ and n ₂ respectively represent the order of the auxiliary object and the main object; the gain coefficient and time constant in the formula can be adjusted according to different The capacity of the unit is determined. In a typical thermal power unit superheated steam temperature system, the gain of the auxiliary object is generally in the range of 0.8 to 6.0, and the time constant is generally in the range of 9 to 30; the gain of the main object is generally in the range of 0.8 to 1.5. , the time constant is generally in the range of 20 to 30.

2) Use the reduced-order first-order expansion state observer algorithm to compensate the desuperheating water valve opening u(k-1) of the previous calculation step, and the input of the compensation algorithm is the desuperheating water valve opening u of the previous calculation step. (k-1) and superheater inlet steam temperature y ₁ (k-1), the output is the compensation value u _f (k) of the current step sequence; where k represents the calculation step sequence, and the Euler method is used in practical applications to calculate the value The calculation of the differential can realize the discrete active disturbance rejection control method. The Euler numerical differential algorithm is as follows:

Where h represents the sampling interval time, and x represents the first derivative of the variable x with respect to time; the specific mathematical form of the compensation algorithm is as follows:

Among them, z ₄ (k-1) and z ₄ (k) represent the intermediate variable values in the compensation algorithm of the previous calculation step and the current calculation step, respectively; β ₄ and b ₁ are the adjustable parameters of the compensation link, where β ₄ >0, b ₁ <0;

3) The current calculation step value y ₂ (k) of the superheated steam temperature and the compensation value u _f (k) of the current calculation step obtained by the compensation algorithm are estimated and compensated in real time by the expansion state observation algorithm, and the superheated steam temperature is obtained. 1. The tracking value z ₁ (k+1) of the calculation step sequence value y ₂ (k+1), the tracking value z ₂ (k+1) of its first derivative, and the tracking value z of the current calculation step sequence subjected to the total disturbance ₃ (k+1);

The calculation expressions of z ₁ (k+1), z ₂ (k+1) and z ₃ (k+1) are as follows:

In the calculation expression, β ₁ , β ₂ , β ₃ and b ₀ are adjustable parameters of the controller. Wherein, β ₁ >0, β ₂ >0, β ₃ >0, b ₀ <0;

4) The difference between the superheated steam temperature set value r(k+1) of the next calculation step and the tracking value z ₁ (k+1) of the current calculation step value y ₂ (k+1) of the superheated steam temperature After zooming in by k _p times, subtract the k _d times of the observed value z ₂ (k+1) of its first derivative and the observation value z ₃ (k+1) of the total disturbance of the superheated steam temperature object, and the result obtained is then enlarged by 1/b After ₀ times, it is used as the opening value u(k+2) of the desuperheating water valve for the next two calculation steps;

The mathematical formula for the opening value u(k+2) of the desuperheating water valve in the last two calculation steps is as follows:

Among them, k _p and k _d are the adjustable parameters of the controller, and the parameters k _p and k _d can be adjusted according to the control requirements;

5) Update the value of the last two calculation steps of the opening of the desuperheating water valve to u(k+2), and adjust the opening of the desuperheating water valve to the value of u(k+2);

After the opening value of the desuperheating water valve is updated to u(k+2), it is used as the input of the compensation algorithm for the calculation of the next cycle. After u(k+2) enters the superheated steam temperature system, the output value of the superheated steam temperature system is realized. Adjustment.

The implementation of the single-loop superheated steam temperature second-order active disturbance rejection control method that can perform disturbance compensation according to the above steps, compared with the traditional cascade control system shown in FIG. 1, the present invention makes the input of the ESO change by adding a compensation algorithm. , the compensation for the secondary disturbance is implemented, the single-loop control of the superheated steam temperature is realized, and the structure of the superheated steam temperature control system is simplified; combined with Figure 2 and Figure 3, the present invention inherits the simple control structure of the standard ADRC, and adds a compensation algorithm by adding a compensation algorithm. , so that the secondary disturbance can be smoothly overcome.

Next, the technical superiority of the present invention will be described through an embodiment, which will be described by taking the superheated steam temperature control of a 150MW thermal power unit as an example:

1) Define the transfer function relationship between the steam temperature at the inlet of the superheater and the opening of the desuperheating water valve as the secondary object, and the transfer function relationship between the steam temperature at the outlet of the superheater and the steam temperature at the inlet of the superheater as the main object; take the superheated steam temperature system The secondary object and the main object in are described by high-order inertial links respectively, and the mathematical expression is as follows:

Among them, Y ₁ (s) is the inlet temperature of the superheater, Y ₂ (s) is the outlet temperature of the superheater, the opening of the desuperheating water valve is U(s), s represents the differential operator, and K ₁ and K ₂ represent the sub-object and The gain coefficient of the main object, T ₁ and T ₂ respectively represent the time constants of the auxiliary object and the main object, and n ₁ and n ₂ respectively represent the orders of the auxiliary object and the main object; K ₁ =1.1428, K ₂ = 0.8697, T ₁ =9.2912, T ₂ =24.5686, n ₁ =2, and n ₂ =4.

2) Use the reduced-order first-order expansion state observer algorithm to compensate the desuperheating water valve opening u(k-1) of the previous calculation step, and the input of the compensation algorithm is the desuperheating water valve opening u of the previous calculation step. (k-1) and superheater inlet steam temperature y ₁ (k-1), the output is the compensation value u _f (k) of the current step sequence; the specific mathematical form of the compensation algorithm is as follows:

Among them, h represents the sampling interval time, z ₃ (k-1) and z ₃ (k) represent the intermediate variable values in the compensation algorithm of the previous calculation step and the current calculation step, respectively; β ₃ and b ₁ are the parameters of the compensation link. Tuning parameters, where β ₃ is 4, b ₁ is -0.028;

3) The current calculation step value y ₂ (k) of the superheated steam temperature and the compensation value u _f (k) of the current step obtained by the compensation algorithm are estimated and compensated in real time by the expansion state observation algorithm, and the superheated steam temperature next Calculate the tracking value z ₁ (k+1) of the step sequence value y ₂ (k+1) and the observed value z ₂ (k+1) of the current calculation step sequence due to the total disturbance;

The calculation expressions of z ₁ (k+1) and z ₂ (k+1) are as follows:

In the calculation expression, β ₁ , β ₂ and b ₀ are adjustable parameters of the controller, k represents the calculation step sequence, and h represents the sampling interval time. Among them, the value of β ₁ is 0.4, the value of β ₂ is 0.04, and the value of b ₀ is -0.12;

4) The difference between the superheated steam temperature set value r(k+1) of the next calculation step and the tracking value z ₁ (k+1) of the superheated steam temperature of the next calculation step value y ₂ (k+1) After the value is amplified by k _p times, the observed value z ₂ (k+1) of the total disturbance of the superheated steam temperature system is subtracted, and the obtained result is amplified by 1/b ₀ times and used as the opening value of the desuperheating water valve in the next two calculation steps. u(k+2);

The mathematical formula for the opening value u(k+2) of the desuperheating water valve in the last two calculation steps is as follows:

Among them, k _p is an adjustable parameter of the controller, and the value of k _p is 0.05.

5) Update the value of the last two calculation steps for the opening of the desuperheating water valve to u(k+2), and adjust the opening of the desuperheating water valve to the value of u(k+2).

After the opening value of the desuperheating water valve is updated to u(k+2), it is used as the input of the compensation algorithm for the calculation of the next cycle. After u(k+2) enters the superheated steam temperature system, the output value of the superheated steam temperature system can be adjusted.

Fig. 6 shows the comparison results of different control strategies and policies according to the embodiment, in which the solid line is the simulation result of the single-loop superheated steam temperature automatic disturbance rejection control method based on disturbance compensation proposed by the present invention, and the dashed line and the dashed-dotted line are the PI-PI strings respectively. The simulation results of the first-order ADRC-PI cascade control and the standard first-order ADRC-PI cascade control, the dotted line is the set value. The specific simulation process is as follows: at the start of the simulation, the system is in a stable state, the set value is changed from 0 to 1 at 100 seconds, the sub-object disturbance with an amplitude of 1 is added at 1100 seconds, and the amplitude of 1 is added at 2000 seconds. Main object perturbation. It can be seen from the simulation results that the single-loop superheated steam temperature active disturbance rejection control method based on disturbance compensation can take into account the reference tracking and disturbance rejection capability of the system, has a faster tracking speed and disturbance rejection recovery speed, and can improve the control performance of the system.

Fig. 7 and Fig. 8 respectively compare the simulation machine test of the superheated steam temperature control of thermal power units based on the single-loop superheated steam temperature automatic disturbance rejection control method based on disturbance compensation, the PI-PI cascade control method and the standard first-order ADRC-PI cascade control method picture. By configuring the distributed control system platform in the simulator according to the single-loop ADR control block diagram based on disturbance compensation shown in Figure 4, the proposed single-loop improved ADR algorithm based on disturbance compensation is realized. In Fig. 7 and Fig. 8, the solid line is the test result of the single-loop superheated steam temperature improvement active disturbance rejection control method based on disturbance compensation proposed by the present invention, and the dotted line and the dot-dash line are the PI-PI cascade control and the standard first-order control method respectively The test results of ADRC-PI cascade control, the dotted line is the set value. In Figure 7, the superheated steam temperature setpoint changes from 535°C to 533°C at 500 seconds. In Figure 8, a desuperheating water opening disturbance with an amplitude of 2 was added at 500 seconds. As can be seen from FIG. 7 , the control strategy in the present invention has a faster tracking setpoint speed; as can be seen from FIG. 8 , the control strategy in the present invention can more smoothly overcome the influence of valve disturbance on the temperature of superheated steam. To sum up, the single-loop active disturbance rejection control method based on disturbance compensation of the present invention can simplify the structure of the superheated steam temperature control system and obtain better control quality.

Claims (2)

1. A disturbance compensation single-loop superheated steam temperature first-order active disturbance rejection control method is characterized by comprising the following steps:

1) defining a transfer function relationship between the superheater inlet steam temperature and the opening of the temperature reduction water valve as an auxiliary object, and defining a transfer function relationship between the superheater outlet steam temperature and the superheater inlet steam temperature as a main object; the auxiliary object and the main object in the superheated steam temperature system are respectively described by a high-order inertia link, and the mathematical expression of the auxiliary object and the main object is as follows:

wherein Y is₁(s) superheater inlet temperature, Y₂(s) is the superheater outlet temperature, U(s) is the desuperheating water valve opening degree, s represents a differential operator, K₁、K₂Respectively representing the gain coefficients, T, of the secondary and primary objects₁、T₂Respectively representing the time constants of the sub-object and the main object, n₁、n₂Respectively representing the order of the sub-object and the main object;

2) compensating the opening u (k-1) of the desuperheating water valve of the last calculation step by utilizing a reduced-order first-order extended state observer algorithm, wherein the input of the compensation algorithm is the opening u (k-1) of the desuperheating water valve of the last calculation step and the steam temperature y at the inlet of the superheater₁(k-1) outputting the compensation value u of the current step sequence_f(k)；

The specific mathematical form is as follows:

where k denotes the calculation step, h denotes the sampling interval time, z₃(k-1) and z₃(k) Representing the values of intermediate variables in the compensation algorithm for the last calculation step and the current calculation step, respectively β₃And b₁To compensate for adjustable parameters of the link, β₃>0，b₁<0；

3) Calculating the current step sequence value y of the superheated steam temperature₂(k) And a compensation value u of the current step sequence obtained by a compensation algorithm_f(k) Real-time estimation and compensation calculation are carried out through an expansion state observation algorithm to obtain a calculation step sequence value y at the superheated steam temperature₂Tracking value z of (k +1)₁(k +1) and the observed value z of the next calculation step sequence under the total disturbance₂(k+1)：

In the computational expression, β₁、β₂And b₀Adjustable parameters for the controller, among others, β₁>0，β₂>0，b₀<0；

4) The following two calculation steps of valve opening value u (k +2) were obtained using the following formula:

wherein k is_pR (k +1) is an output set value of the next calculation step sequence;

5) and updating the input values of the last two calculation steps of the superheated steam temperature system to u (k +2), and adjusting the opening of the desuperheating water valve to the value of u (k +2) so that the output value of the superheated steam temperature system tracks the set value.

2. A disturbance compensation single-loop superheated steam temperature second-order active disturbance rejection control method is characterized by comprising the following steps:

1) defining a transfer function relationship between the superheater inlet steam temperature and the opening of the temperature reduction water valve as an auxiliary object, and defining a transfer function relationship between the superheater outlet steam temperature and the superheater inlet steam temperature as a main object; the auxiliary object and the main object in the superheated steam temperature system are respectively described by a high-order inertia link, and the mathematical expression is as follows:

wherein Y is₁(s) superheater inlet temperature, Y₂(s) superheater outlet temperature, U(s) desuperheater valve opening, s differential operator, K₁、K₂Respectively representing the gain coefficients, T, of the secondary and primary objects₁、T₂Respectively representing the time constants of the sub-object and the main object, n₁、n₂Respectively representing the order of the sub-object and the main object;

2) calculating the last one by using a reduced order first order extended state observer algorithmCompensating the opening u (k-1) of the desuperheating water valve of the step sequence, wherein the input of the compensation algorithm is the opening u (k-1) of the desuperheating water valve of the last calculation step sequence and the steam temperature y at the inlet of the superheater₁(k-1) outputting the compensation value u of the current step sequence_f(k)；

The specific mathematical form is as follows:

where k denotes the calculation step, h denotes the sampling interval time, z₄(k-1) and z₄(k) Representing the values of intermediate variables in the compensation algorithm for the last calculation step and the current calculation step, respectively β₄And b₁To compensate for adjustable parameters of the link, β₄>0，b₁<0；

3) Calculating the current step sequence value y of the superheated steam temperature₂(k) And a compensation value u of the current calculation step sequence obtained by a compensation algorithm_f(k) Real-time estimation and compensation calculation are carried out through an expansion state observation algorithm to obtain a calculation step sequence value y at the superheated steam temperature₂Tracking value z of (k +1)₁(k +1), tracking value z of its first derivative₂(k +1) and the tracking value z of the next calculation step sequence under the total disturbance₃(k+1)：

In the computational expression, β₁、β₂、β₃And b₀Adjustable parameters for the controller, among others, β₁>0，β₂>0，β₃>0，b₀<0；

4) The following two calculation steps of valve opening value u (k +2) were obtained using the following formula:

wherein k is_p、k_dFor the controller adjustable parameters, r (k +1)Outputting a set value for the next calculation step;

5) and updating the input values of the last two calculation steps of the superheated steam temperature system to u (k +2), and adjusting the opening of the desuperheating water valve to the value of u (k +2) so that the output value of the superheated steam temperature system tracks the set value.

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