阅读说明：本技术 一种天然气智能加臭控制装置及控制方法 (Intelligent natural gas odorization control device and control method ) 是由 葛亮 罗明 母小琳 阳彩霞 韦国晖 胡泽 肖国清 于 2020-05-12 设计创作，主要内容包括：本发明公开了一种天然气智能加臭控制装置及控制方法,该装置包含：加臭机、加臭剂在线检测仪、预测自抗扰控制器、补偿执行机构和天然气流量检测仪；预测自抗扰控制器根据天然气管道的天然气流量值确定加臭剂浓度的设定值,将设定值信号发送给加臭机以控制加臭剂浓度,并根据加臭剂在线检测仪测得的加臭剂浓度值,由预测自抗扰控制器根据自抗扰技术与Smith补偿器结合的控制方法对加臭剂浓度进行补偿,并将补偿信号发送给补偿执行机构,控制加臭机输出加臭剂的补偿量。本发明的控制方法能够考虑浓度的衰减及系统内部的不确定性和外部的温度干扰,保证实时精确控制天然气管网末端实际的加臭剂浓度。(The invention discloses a natural gas intelligent odorization control device and a control method, wherein the device comprises: the system comprises an odorizing machine, an odorizing agent on-line detector, a prediction active disturbance rejection controller, a compensation actuating mechanism and a natural gas flow detector; the prediction active disturbance rejection controller determines a set value of the odorizing agent concentration according to a natural gas flow value of a natural gas pipeline, sends a set value signal to the odorizing machine to control the odorizing agent concentration, compensates the odorizing agent concentration according to a control method of combining an active disturbance rejection technology and a Smith compensator according to the odorizing agent concentration value measured by the online odorizing agent detector, sends a compensation signal to a compensation execution mechanism, and controls the odorizing machine to output the compensation amount of the odorizing agent. The control method can consider the attenuation of the concentration, the uncertainty inside the system and the external temperature interference, and ensure the real-time accurate control of the actual odorizing agent concentration at the tail end of the natural gas pipe network.)

1. An intelligent natural gas odorization control device, characterized in that the device contains: the system comprises an odorizing machine (10), an odorizing agent online detector (30), a prediction active disturbance rejection controller (40), a compensation execution mechanism (50) and a natural gas flow detector (60);

the output port of the odorizing machine (10) is connected with a natural gas pipeline (20), and the tail end of the natural gas pipeline (20) is provided with an odorizing agent online detector (30) for detecting the actual output value of the concentration of the odorizing agent at the tail end of the natural gas pipeline; the natural gas flow detector (60) is used for detecting the flow of natural gas in the natural gas pipeline (20);

the output ports of the odorizing agent online detector (30) and the natural gas flow detector (60) are connected with the input port of the prediction active disturbance rejection controller (40), the output port of the prediction active disturbance rejection controller (40) is connected with the input ports of the odorizing machine (10) and the compensation executing mechanism (50), and the output port of the compensation executing mechanism (50) is connected with the input port of the odorizing machine (10);

the predicted active disturbance rejection controller (40) determines a set value of odorizing agent concentration of the odorizing machine (10) according to a natural gas flow value output to a natural gas pipeline (20) by a natural gas gasifier, sends a set value signal of the odorizing agent concentration to the odorizing machine (10) to control the odorizing agent concentration output by the odorizing machine (10), compensates the odorizing agent concentration according to a control method of combining an active disturbance rejection technology and a Smith compensator by the predicted active disturbance rejection controller (40) according to an odorizing agent concentration value actually measured by an odorizing agent on-line detector (30) at the tail end of the natural gas pipeline (20), and sends a compensation signal to the compensation execution mechanism (50), wherein the compensation execution mechanism (50) controls the odorizing machine (10) to output a compensation amount of the odorizing agent according to the compensation signal of the predicted active disturbance rejection controller (40);

wherein the predictive auto-disturbance-rejection controller (40) controls the amount of odorant compensation by auto-disturbance-rejection technique in combination with the Smith compensator, which constructs a model G of the Smith compensator_m(S) is:

wherein, K_m、T_m1、T_m2、τ_mModel parameters of the Smith compensator, respectively, and controlled object model parameters K, T, respectively₁、T₂τ; k is the system gain; t is₁And T₂Is a time constant; s is a complex variable of Laplace transformation; tau is the pure lag time caused by the length of the pipe network;

considering the uncertainty of the inside of the system formed by the device and the natural gas pipeline and the interference of the outside temperature, a nonlinear Extended State Observer (ESO) is constructed, and the control algorithm of the ESO is as follows:

wherein, β₀₁、β₀₂、β₀₃Three adjustable parameters, b₀Is a compensation factor; y' is the output of the Smith compensator; y is the actual output value of the concentration of the odorizing agent in the natural gas pipeline; z is a radical of₁、z₂An estimate of y; z is a radical of₃Real-time estimation values of total disturbance including disturbance inside the system and external temperature disturbance are obtained; u is a control quantity which represents the compensation quantity of the odorizing agent corrected by the active disturbance rejection technology and the Smith compensator; fal (·) is a nonlinear function defined as:

wherein, the value is the size of the system error; alpha is an index; to distinguish the margin of error magnitude;

the tracking differentiator TD preprocesses the set value input signal v of the odorizing agent concentration by quickly tracking the input signal to obtain a derivative differentiated signal thereof at a control rate of:

wherein v is an odorizing agent concentration set value input signal; v. of₁A tracking signal v output in accordance with an odorant concentration set value input signal v₂Is v is₁The differential signal of (a); r is a transition process speed factor, and the larger r is, the shorter the transition time is; h is₀Is a filter factor; fst (-) is a non-linear function;

the algorithm of the nonlinear error feedback control rate NLSEF of the predictive active disturbance rejection controller (40) is as follows:

wherein e is₁、e₂For tracking the tracking signal v output by the differentiator TD₁Extracted differential signal v₂And the estimated state variable z of the nonlinear extended state observer, ESO₁、z₂The difference values formed respectively;₀、β₁、β₂is an adjustable parameter.

2. An intelligent natural gas odorization control device according to claim 1, characterized in that the algorithm of the nonlinear function fst (-) is:

wherein d, d₀、y₀、a₀And a is an intermediate variable.

3. The intelligent natural gas odorizing control device according to claim 1 or 2, characterized in that the odorizing machine (10) is connected to an output port of an odorizing agent tank (1), and the odorizing agent tank (1) is used for adding odorizing agent to the odorizing machine (10).

4. The intelligent natural gas odorizing control device according to claim 1 or 2, wherein the natural gas flow detector (60) adopts a differential pressure type flow meter.

5. The intelligent natural gas odorizing control device according to claim 1 or 2, wherein the odorizing agent online detector (30) is a THT online detector.

6. A method for intelligently controlling the concentration of natural gas odorizing agent is characterized in that the method constructs a prediction active disturbance rejection controller combining an active disturbance rejection technology and a Smith compensator, estimates and compensates the uncertainty of a system formed by a natural gas intelligent odorizing control device and a natural gas pipeline and the external temperature disturbance, and determines the compensation amount of the odorizing agent;

model G of the constructed Smith compensator_m(S) is:

wherein, K_m、T_m1、T_m2、τ_mModel parameters of the Smith compensator, respectively, and controlled object model parameters K, T, respectively₁、T₂τ; k is the system gain; t is₁And T₂Is a time constant; s is a complex variable of Laplace transformation; tau is the pure lag time caused by the length of the pipe network;

considering the uncertainty of the inside of the system formed by the device and the natural gas pipeline and the interference of the outside temperature, a nonlinear Extended State Observer (ESO) is constructed, and the control algorithm of the ESO is as follows:

wherein, β₀₁、β₀₂、β₀₃Three adjustable parameters, b₀Is a compensation factor; y' is the output of the Smith compensator; y is the actual output value of the odorizing agent concentration in the gas pipeline; z is a radical of₁、z₂An estimate of y; z is a radical of₃Real-time estimation values of total disturbance including disturbance inside the system and external temperature disturbance are obtained; u is a control quantity which represents the compensation quantity of the odorizing agent corrected by the active disturbance rejection technology and the Smith compensator; fal (·) is a nonlinear function defined as:

wherein, the system error is the size; alpha is an index; to distinguish the margin of error magnitude;

the tracking differentiator TD preprocesses the set value input signal v of the odorizing agent concentration by quickly tracking the input signal to obtain a derivative differentiated signal thereof at a control rate of:

wherein v is an odorizing agent concentration set value input signal; v. of₁A tracking signal v output in accordance with an odorant concentration set value input signal v₂Is v is₁The differential signal of (a); r is a transition process speed factor, and the larger r is, the shorter the transition time is; h is₀Is a filter factor; fst (-) is a non-linear function;

the algorithm of the nonlinear error feedback control rate NLSEF of the predictive active disturbance rejection controller is as follows:

wherein e is₁、e₂For tracking the tracking signal v output by the differentiator TD₁Extracted differential signal v₂And the estimated state variable z of the nonlinear extended state observer, ESO₁、z₂The difference values formed respectively;₀、β₁、β₂is an adjustable parameter.

7. The method for intelligently controlling the concentration of natural gas odorizing agent according to claim 6, wherein the algorithm of the nonlinear function fst (-) is:

wherein d, d₀、y₀、a₀And a is an intermediate variable.

8. The method for intelligently controlling the concentration of natural gas odorizing agent according to claim 6, characterized in that a time lag mathematical model of the odorizing agent concentration occurring with the length of the pipeline is established through a mathematical model of the odorizing agent concentration attenuation, and a Smith compensator is constructed based on the mathematical model to compensate for the time lag;

the attenuation mathematical model is as follows:

where K is the system gain, T₁And T₂Is a time constant, S is a complex variable of the Laplace transform;

the time-lag mathematical model is as follows:

wherein tau is the pure lag time caused by the length of the pipe network, and S is the complex variable of Laplace transformation.

9. The method for intelligently controlling the concentration of natural gas odorizing agent according to any one of claims 6 to 9, wherein the equation of state of the controlled object odorizing agent concentration is:

wherein f (-) is total disturbance and comprises system nonlinearity, parameter change and an external temperature interference dynamic model; b is a control input matrix; ω (t) is the interference caused by the outside temperature; x and x₂Are all system state variables; u (t) is the system control input; x (t) is the system state; t is time.

Technical Field

The invention relates to a concentration control method for natural gas odorizing agent, in particular to an intelligent natural gas odorizing control device and a control method.

Background

In the natural gas industry, odorization is an essential part. The odorizing agent is an organic compound or a mixture with strong odor, and has the characteristics of sulfur, low toxicity, flammability, explosiveness, high price and the like. When added to gas at very low concentrations, the gas is given a particular unpleasant warning odor so that the leaking gas is perceived when it reaches its lower explosive limit of 5% or a harmful concentration acceptable to humans. However, if the odorizing amount is insufficient, the gas may leak without a safety warning effect, thereby causing a safety accident. In addition, if the odorizing amount is too large, economic loss is caused because the odorizing agent is expensive, and the excessive odorizing agent generates toxic gases such as carbon monoxide and sulfur-containing gas after incomplete combustion, thereby polluting the environment. Therefore, it is an urgent problem to achieve the concentration of odorizing agents in natural gas to reach the national standard.

Generally, the natural gas odorizing device adopts a closed-loop odorizing mode, and the controller realizes odorizing adjustment by comparing the set output quantity of the odorizing agent with the actual output quantity of the odorizing agent, so that the concentration of the odorizing agent in the natural gas is ensured to reach the national standard. For example, chinese utility model patent application No. CN201220450693.0 discloses an odorizing device output detection compensation system, which adopts the odorizing device of closed loop odorizing mode, can detect odorizing pump odorizing agent actual output quantity, and the controller sets output quantity and odorizing agent actual output quantity through comparing odorizing agent, outputs odorizing agent output compensation quantity signal to compensation actuating mechanism, and compensation actuating mechanism changes odorizing pump odorizing agent actual output quantity according to odorizing agent output compensation quantity. Although the invention takes into account the difference between the set amount of odorizing agent and the actual output amount, and adjusts the amount of odorizing agent by this difference in concentration.

For another example, chinese patent application No. cn201811455499.x discloses an LNG odorizing agent concentration control system and a method thereof, which detects odorizing agent concentration in natural gas by a detection device, detects natural gas flow by a flow meter, and thereby controls the operating frequency of an odorizing machine by the obtained concentration data and flow data.

However, in the two inventions, the attenuation of the odorizing agent concentration in the natural gas pipe network caused by the pipe network length and the pipe adsorption is not considered, and the pipe network length can also cause the time lag phenomenon of the system, so that the system can not respond to the dynamic change in time, and the adverse phenomena of large overshoot and large response time of the whole system can be caused.

Disclosure of Invention

The invention aims to provide an intelligent natural gas odorizing control device and a control method, which solve the problem that the concentration attenuation of odorizing agents is not considered in the existing method, can consider the attenuation of the concentration, the internal uncertainty of a system and the external temperature interference, and ensure that the actual odorizing agent concentration at the tail end of a natural gas pipe network is accurately controlled in real time.

In order to achieve the above object, the present invention provides an intelligent odorization control device for natural gas, comprising: the device comprises an odorizing machine, an odorizing agent on-line detector, a prediction active disturbance rejection controller, a compensation executing mechanism and a natural gas flow detector.

The system comprises a gas pipeline, an odorizing machine, an on-line odorizing agent detector, a gas pipeline control unit and a gas pipeline control unit, wherein an output port of the odorizing machine is connected with the gas pipeline, and the tail end of the gas pipeline is provided with the odorizing agent on-line detector for detecting the actual output value of the concentration of the odorizing agent at the tail end of the gas pipeline; the natural gas flow detector is used for detecting the flow of natural gas in a natural gas pipeline.

The output ports of the odorizing agent on-line detector and the natural gas flow detector are connected with the input port of the prediction active disturbance rejection controller, the output port of the prediction active disturbance rejection controller is connected with the input ports of the odorizing machine and the compensation executing mechanism, and the output port of the compensation executing mechanism is connected with the input port of the odorizing machine.

The prediction active disturbance rejection controller determines a set value of odorizing agent concentration of the odorizing machine according to a natural gas flow value output to a natural gas pipeline by a natural gas gasifier, sends a set value signal of the odorizing agent concentration to the odorizing machine to control the odorizing agent concentration output by the odorizing machine, compensates the odorizing agent concentration according to a control method of combining an active disturbance rejection technology and a Smith compensator according to an odorizing agent concentration value actually measured by an odorizing agent on-line detector at the tail end of the natural gas pipeline, and sends a compensation signal to the compensation execution mechanism, and the compensation execution mechanism controls the odorizing machine to output the compensation amount of the odorizing agent according to the compensation signal of the prediction active disturbance rejection controller.

Wherein the predictive auto-disturbance-rejection controller controls the compensation amount of the odorizing agent by combining the auto-disturbance-rejection technology with the Smith compensator, and the model G of the Smith compensator is constructed_m(S) is:

wherein, K_m、T_m1、T_m2、τ_mModel parameters of the Smith compensator, respectively, and controlled object model parameters K, T, respectively₁、T₂τ; k is the system gain; t is₁And T₂Is a time constant; s is a complex variable of Laplace transformation; tau is the net lag time caused by the length of the pipe network.

Considering the uncertainty of the inside of the system formed by the device and the natural gas pipeline and the interference of the outside temperature, a nonlinear Extended State Observer (ESO) is constructed, and the control algorithm of the ESO is as follows:

wherein, β₀₁、β₀₂、β₀₃Three adjustable parameters, b₀Is a compensation factor; y' is the output of the Smith compensator; y is the actual output value of the odorizing agent concentration in the gas pipeline; z is a radical of₁、z₂An estimate of y; z is a radical of₃Real-time estimation values of total disturbance including disturbance inside the system and external temperature disturbance are obtained; u is a control quantity which represents the compensation quantity of the odorizing agent corrected by the active disturbance rejection technology and the Smith compensator; fal (·) is a nonlinear function defined as:

wherein, the system error is the size; alpha is an index; to distinguish the margin of error magnitude.

The tracking differentiator TD preprocesses the set value input signal v of the odorizing agent concentration by quickly tracking the input signal to obtain a derivative differentiated signal thereof at a control rate of:

wherein v is an odorizing agent concentration set value input signal; v. of₁A tracking signal v output in accordance with an odorant concentration set value input signal v₂Is v is₁The differential signal of (a); r is a transition process speed factor, and the larger r is, the shorter the transition time is; h is₀Is a filter factor; fst (-) is a non-linear function.

The algorithm of the nonlinear error feedback control rate NLSEF of the predictive active disturbance rejection controller is as follows:

wherein e is₁、e₂For tracking the tracking signal v output by the differentiator TD₁Extracted differential signal v₂And the estimated state variable z of the nonlinear extended state observer, ESO₁、z₂The difference values formed respectively;₀、β₁、β₂is an adjustable parameter.

Preferably, the algorithm of the nonlinear function fst (-) is:

wherein d, d₀、y₀、a₀And a is an intermediate variable.

Preferably, the odorizing machine is connected to an outlet of an odorizing agent tank for adding odorizing agent to the odorizing machine.

Preferably, the natural gas flow detector adopts a differential pressure type flowmeter.

Preferably, the odorizing agent on-line detector adopts a THT on-line detector.

Another object of the present invention is to provide a method for intelligently controlling the concentration of natural gas odorizing agent, which constructs a predictive active disturbance rejection controller combining an active disturbance rejection technique with a Smith compensator, estimates and compensates for the uncertainty of a system formed by a natural gas intelligent odorizing control device and a natural gas pipeline and external temperature disturbance, and determines the compensation amount of odorizing agent.

Model G of the constructed Smith compensator_m(S) is:

wherein, K_m、T_m1、T_m2、τ_mModel parameters of the Smith compensator, respectively, and controlled object model parameters K, T, respectively₁、T₂τ; k is the system gain; t is₁And T₂Is a time constant;s is a complex variable of Laplace transformation; tau is the net lag time caused by the length of the pipe network.

Considering the uncertainty of the inside of the system formed by the device and the natural gas pipeline and the interference of the outside temperature, a nonlinear Extended State Observer (ESO) is constructed, and the control algorithm of the ESO is as follows:

wherein, β₀₁、β₀₂、β₀₃Three adjustable parameters, b₀Is a compensation factor; y' is the output of the Smith compensator; y is the actual output value of the odorizing agent concentration in the gas pipeline; z is a radical of₁、z₂An estimate of y; z is a radical of₃Real-time estimation values of total disturbance including disturbance inside the system and external temperature disturbance are obtained; u is a control quantity which represents the compensation quantity of the odorizing agent corrected by the active disturbance rejection technology and the Smith compensator; fal (·) is a nonlinear function defined as:

wherein, the system error is the size; alpha is an index; to distinguish the margin of error magnitude.

The tracking differentiator TD preprocesses the set value input signal v of the odorizing agent concentration by quickly tracking the input signal to obtain a derivative differentiated signal thereof at a control rate of:

wherein v is an odorizing agent concentration set value input signal; v. of₁A tracking signal v output in accordance with an odorant concentration set value input signal v₂Is v is₁The differential signal of (a); r is a transition process speed factor, and the larger r is, the shorter the transition time is; h is₀Is a filter factor; fst (-) is a non-linear function.

The algorithm of the nonlinear error feedback control rate NLSEF of the predictive active disturbance rejection controller is as follows:

wherein e is₁、e₂For tracking the tracking signal v output by the differentiator TD₁Extracted differential signal v₂And the estimated state variable z of the nonlinear extended state observer, ESO₁、z₂The difference values formed respectively;₀、β₁、β₂is an adjustable parameter.

Preferably, the algorithm of the nonlinear function fst (-) is:

wherein d, d₀、y₀、a₀And a is an intermediate variable.

Preferably, a time lag mathematical model of odorizing agent concentration along with the length of the pipeline is established through a mathematical model of odorizing agent concentration attenuation, and a Smith compensator is constructed on the basis of the mathematical model to compensate the time lag;

the attenuation mathematical model is as follows:

where K is the system gain, T₁And T₂S is a complex variable of the lagrange transform, which is a time constant.

The time-lag mathematical model is as follows:

wherein tau is the pure lag time caused by the length of the pipe network, and S is the complex variable of Laplace transformation.

Preferably, the equation of state of the controlled object odorizing agent concentration is:

wherein f (-) is total disturbance and comprises system nonlinearity, parameter change and an external temperature interference dynamic model; b is a control input matrix; ω (t) is the interference caused by the outside temperature; x and x₂Are all system state variables; u (t) is the system control input; x (t) is the system state; t is time.

The intelligent natural gas odorizing control device and the control method solve the problem that the concentration attenuation of the odorizing agent is not considered in the existing method, and have the following advantages that:

(1) the device and the control method of the invention establish a mathematical model of odorizing agent concentration attenuation along with the length of the pipeline and due to the adsorption of the pipeline, and establish a complete mathematical model of a controlled object by combining time lag caused by the length of the pipeline, and consider the uncertainty inside the system and the external temperature interference;

(2) the device and the control method of the invention combine Smith pre-estimation control and active disturbance rejection control, thereby pre-estimating and compensating the total disturbance and time lag of the system, and improving the dynamic performance and the anti-jamming capability of the system;

(3) according to the device, the THT online detector and the differential pressure type flowmeter are adopted, the continuous online monitoring of the odorizing agent concentration at the tail end of the natural gas pipe network can be realized in real time through the THT online detector, the high-precision measurement of the natural gas flow can be realized through the differential pressure type flowmeter, and therefore the odorizing machine is controlled through the acquired odorizing agent concentration data and the natural gas flow data, and the fact that the actual odorizing agent concentration at the tail end of the natural gas pipe network is accurately controlled in real time to reach the national standard is guaranteed.

Drawings

Fig. 1 is a schematic structural diagram of an intelligent natural gas odorization control device.

Fig. 2 is a schematic structural diagram of an intelligent natural gas odorization control device according to embodiment 1 of the present invention.

Fig. 3 is a schematic diagram of the method for intelligently controlling the concentration of natural gas odorizing agent according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.