CN104131872B - The control method of a kind of SCR temperature of reactor and device - Google Patents

Abstract

The invention provides a method and device for controlling the temperature of an SCR reactor. The control method includes: constructing an SCR dynamic temperature model according to the experimental test temperature before the SCR reactor and the two-point method with delay first-order inertia link fitting ; According to the characteristics of the SCR dynamic temperature model, the Smith predictor calculates the compensation value; the compensation value can eliminate the hysteresis link in the SCR dynamic temperature model; calculate the preset temperature of the SCR reactor minus the SCR dynamic The difference between the output of the temperature model and the sum of the compensation value; receive the feedback signal containing the difference, calculate the post-injection amount of the engine according to the difference, and send the post-injection amount with the engine The signal of the quantity is sent to the engine, and the engine is controlled to carry out post-injection according to the post-injection quantity, so as to control the temperature of the SCR reactor. The method improves the stability of the temperature control of the SCR reactor.

Description

A method and device for controlling the temperature of an SCR reactor

technical field

The invention relates to engine tail gas treatment technology, in particular to a method and device for controlling the temperature of an SCR reactor.

Background technique

In order to reduce the nitrogen oxides in engine exhaust emissions, the most effective way at present is to carry out selective catalytic reduction reaction (SCR reaction) on the exhaust gas of the engine, so that the nitrogen oxides in the exhaust gas react with urea to form ammonia and water, thereby reducing emissions to nitrogen oxides in the atmosphere.

During the SCR reaction, the catalytic efficiency of the catalyst in the SCR reactor has a great relationship with the temperature in the SCR reactor. If the temperature in the SCR reactor is too high or too low, the catalytic efficiency of the SCR reaction will be reduced. Therefore, in order to ensure the catalytic efficiency of the SCR reaction, the temperature in the SCR reactor should be controlled within a certain appropriate range.

At present, the method of controlling the temperature of the SCR reactor is to use the difference between the temperature setting value of the SCR reactor and the actual temperature measurement value before the SCR reactor as the feedback signal of the PID controller, and then the PID controller calculates the engine temperature based on the feedback signal. The control signal of the post-injection quantity, so that the engine performs post-injection according to the post-injection quantity signal, and uses the post-injection to increase the temperature of the exhaust gas of the engine, so as to achieve the purpose of controlling the temperature of the SCR reactor. However, the SCR reactor is generally installed after the particulate oxidation catalytic device DOC and the particulate filter DPF. The exhaust gas from the engine has a long pipeline to reach the SCR reactor, and the exhaust gas will lose heat during the transmission process of the pipeline. , and the heat of reaction in the DOC and in the DPF will also cause a change in the exhaust gas temperature. Therefore, the temperature control of the SCR reactor belongs to the link of large lag and large inertia. Therefore, the existing method of directly using the PID controller to control the temperature of the SCR reactor in a closed loop will lead to temperature instability in the SCR reactor and overshoot or response speed. too slow problem.

Contents of the invention

In order to solve the problems of temperature instability in the SCR reactor and overshoot or slow response, the first aspect of the present invention provides a method for controlling the temperature of the SCR reactor.

Based on the first aspect of the present invention, the present invention also provides a device for controlling the temperature of the SCR reactor.

In order to achieve the above-mentioned purpose of the invention, the present invention adopts following technical scheme:

A method for controlling the temperature of an SCR reactor, comprising:

According to the experimental test temperature before the SCR reactor and the two-point method with delayed first-order inertia link fitting, the SCR dynamic temperature model is constructed, and the SCR dynamic temperature model contains a hysteresis link;

According to the dynamic characteristics of the SCR dynamic temperature model, the Smith predictor calculates the compensation value; the compensation value can eliminate the hysteresis link in the SCR dynamic temperature model;

Calculating the preset temperature of the SCR reactor minus the difference between the output of the SCR dynamic temperature model and the sum of the compensation value;

Receive the feedback signal containing the difference, calculate the post-injection amount of the engine according to the difference, and send the signal with the post-injection amount of the engine to the engine, and control the engine according to the post-injection amount After spraying is performed to control the temperature of the SCR reactor.

Preferably, the SCR dynamic temperature model also includes a first-order inertia link.

Preferably, the transfer function of the SCR dynamic temperature model is:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain, T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform.

Preferably, the transfer function of the Smith predictor is as follows:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain, T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform.

Preferably, the PID controller receives the feedback signal containing the difference, calculates the post fuel injection quantity of the engine, and sends the signal with the post fuel injection quantity of the engine to the engine, and controls the engine to follow the post injection quantity. The amount of fuel injection is carried out after the step of spraying to control the temperature of the SCR reactor.

A control device for the temperature of an SCR reactor, comprising:

Constructing an SCR dynamic temperature model unit, which is used to construct an SCR dynamic temperature model according to the experimental test temperature before the SCR reactor and a two-point method with a delayed first-order inertia link fitting; the SCR dynamic temperature model contains a hysteresis link;

The first calculation unit is used to calculate the compensation value by the Smith predictor according to the dynamic characteristics of the SCR dynamic temperature model; the compensation value can eliminate the hysteresis link in the SCR dynamic temperature model;

The second calculation unit is used to calculate the preset temperature of the SCR reactor minus the difference between the output of the SCR dynamic temperature model and the sum of the compensation value;

The control unit is used to receive the feedback signal containing the difference, calculate the post-injection amount of the engine according to the difference, and send the signal with the post-injection amount of the engine to the engine, and control the engine to The post-injection is carried out according to the above-mentioned post-injection quantity to control the temperature of the SCR reactor.

Preferably, the transfer function of the SCR dynamic temperature model is:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain, T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform.

Preferably, the transfer function of the Smith predictor is as follows:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain, T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform.

Preferably, the control unit is a PID controller adding a Smith predictor, wherein the transfer function of the control unit can be expressed as:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; .</span>$

Compared with the prior art, the present invention has the following beneficial effects:

In the method for controlling the temperature of the SCR reactor provided by the present invention, the Smith predictor calculates the compensation value capable of compensating the hysteresis link in the SCR dynamic temperature model according to the dynamic characteristics of the constructed SCR dynamic model, and uses the preset value of the SCR reactor The difference between the temperature minus the output of the SCR dynamic temperature model and the sum of the compensation value is used as the feedback signal of the PID controller, so that the delayed controlled quantity is reacted on the PID controller in advance, thereby reducing or eliminating the SCR The hysteresis of the reactor temperature control reduces the overshoot of the PID controller controlling the temperature of the SCR reactor, improves the response speed of the SCR reactor, and further improves the stability of the temperature control of the SCR reactor.

Description of drawings

In order to clearly understand the technical solution of the present invention, the accompanying drawings that need to be used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only part of the embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is a schematic flow chart of a method for controlling the temperature of an SCR reactor provided by an embodiment of the present invention;

Fig. 2 is the overall control block diagram of the control method of SCR reactor temperature provided by the embodiment of the present invention;

Fig. 3 is a transfer function block diagram in the method for controlling the temperature of the SCR reactor provided by the embodiment of the present invention;

Fig. 4 is a schematic diagram of the temperature control device of the SCR reactor provided by the embodiment of the present invention.

detailed description

The specific implementation of the method for controlling the temperature of the SCR reactor provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 1 , FIG. 1 is a schematic flowchart of a method for controlling the temperature of an SCR reactor provided by an embodiment of the present invention. As shown in Figure 1, the control method includes the following steps:

S101. According to the experimental test temperature before the SCR reactor and the two-point method with delayed first-order inertia link fitting, construct the SCR dynamic temperature model, and the SCR dynamic temperature model contains a hysteresis link:

Usually, the post-injection of the engine is used in this technical field to control the exhaust temperature of the engine exhaust, but the SCR reactor is usually located after the oxidation catalytic device DOC and the particle trap DPF of the particulate matter, and the engine exhaust is transmitted to the SCR reactor. There is heat loss in the passing pipeline, and DOC and DPF will release heat during the reaction process, so these factors will affect the exhaust gas temperature reaching the SCR reactor, resulting in the SCR temperature control process belonging to a large lag and large inertia link.

It should be noted that the post-injection is one of the multiple injections of the engine, and it is an injection lagging behind the main injection, and is used to increase the exhaust temperature of the engine. Among them, the main jet is mainly used to do work.

On the premise of considering the heat loss of the pipeline mentioned above, the reaction heat release of DOC and DPF and other factors that affect the temperature of the exhaust gas, the actual temperature before the SCR reactor was measured through multiple experiments, and according to the delayed first-order inertia link The fitting two-point method constructs the SCR dynamic temperature model. Since the SCR temperature control belongs to the hysteresis link, the constructed SCR dynamic temperature model includes the hysteresis link. It should be noted that the SCR dynamic temperature model is related to factors such as the length, surface area, exhaust gas flow, and ambient temperature of the SCR processor.

According to the energy conversion, and considering the above-mentioned factors affecting the exhaust temperature such as the heat loss of the pipeline, the reaction heat release of DOC and DPF, the SCR dynamic temperature model can be simplified into a first-order inertial link and a hysteresis link. And, further, the transfer function of the SCR dynamic temperature model can be simplified to formula (1):

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain; T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform.

S102. According to the dynamic characteristics of the SCR dynamic temperature model, the Smith predictor calculates a compensation value; the compensation value can eliminate the hysteresis link in the SCR dynamic temperature model:

It should be noted that the dynamic characteristics of the SCR dynamic temperature model refer to the characteristics that the temperature in front of the SCR reactor will change in real time with time.

According to the dynamic characteristics of the SCR dynamic temperature model constructed above, the Smith predictor calculates the compensation value, which can eliminate the hysteresis link in the SCR dynamic temperature model.

It should be noted that the Smith estimator described in the embodiment of the present invention is calculated based on the above-mentioned SCR dynamic temperature model, and the Smith estimator aims to eliminate hysteresis in the SCR dynamic temperature model.

When the transfer function of the SCR dynamic temperature model is shown in formula (1), the transfer function of the Smith predictor can be shown in formula (2):

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain; T represents the time constant, and τ represents the delay time. s is the complex parameter in the Laplace transform.

S103. Calculate the difference obtained by subtracting the preset temperature of the SCR reactor from the sum of the output of the SCR dynamic temperature model and the compensation value.

S104: Receive the feedback signal containing the difference, calculate the post-injection amount of the engine according to the difference, and send the signal with the post-injection amount of the engine to the engine, and control the engine to follow the post-injection The amount of oil is post-sprayed to control the temperature of the SCR reactor:

Specifically, the method for controlling the temperature of the SCR reactor provided by the embodiment of the present invention can be realized through the closed-loop control of the PID controller. When it is controlled by a PID controller, the difference calculated in step S103 is fed back to the PID controller as an input signal of the PID controller, and the PID controller receives the feedback signal containing the difference, and calculates the engine The amount of post-injection fuel to make the exhaust temperature of the engine reach a certain temperature.

The PID controller sends a signal with the post-injection amount of the engine to the engine, and controls the engine to perform post-injection according to the post-injection amount, so as to increase the exhaust temperature of the engine, and then control the temperature of the SCR reactor.

The above is the specific implementation manner of the method for controlling the temperature of the SCR reactor provided by the embodiment of the present invention. In the method for controlling the temperature of the SCR reactor of the present invention, the preset temperature of the SCR reactor is subtracted from the output of the SCR dynamic temperature model and the sum of the compensation value obtained as the feedback signal of the PID controller, due to Smith The compensation value calculated by the estimator can eliminate the hysteresis link in the SCR dynamic temperature model. Therefore, using the above difference as the feedback signal of the PID controller will reflect the hysteresis link in the SCR dynamic temperature model to the PID controller in advance. Therefore, the exhaust gas temperature controlled by the post-injection amount obtained by the PID controller can reach the temperature required by the SCR reactor, so using this method to control the temperature of the SCR reactor can avoid large overshoots and can also Improve responsiveness.

Moreover, compared with the method in the prior art that directly uses the difference between the temperature before the SCR reactor and the preset temperature as the feedback signal of the PID controller, the control method provided by the embodiment of the present invention can make the temperature control of the SCR reactor more stable.

In order to understand the control method provided by the embodiment of the present invention more clearly, the embodiment of the present invention also provides an overall control block diagram of the method for controlling the temperature of the SCR reactor, as shown in FIG. 2 . Among them, the SCR dynamic temperature model and the Smith predictor in the dashed box are the core of the control method of the present invention. Among them, the difference obtained by adding the output result of the SCR dynamic temperature model to the output result of the Smith predictor and subtracting it from the set temperature of the SCR reactor is used as the feedback signal of the PID controller. Then, the PID controller calculates the fuel injection quantity after the engine according to the feedback signal, controls the exhaust gas temperature, and then controls the temperature of the SCR reactor.

Bring the transfer function G _T of the SCR dynamic temperature model, the transfer function G _S of the Smith estimator, and the transfer function G _PID of the PID controller into Figure 2, and the transfer function block diagram of the entire system can be obtained, as shown in Figure 3 .

Wherein, the control logic in the dashed box is a whole, and the transfer function Gp of the whole is the sum of the transfer function G _T of the SCR dynamic temperature model and the transfer function G _S of the Smith predictor. Expressed in mathematical formula as follows:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

It can be seen from the above formula (3) that the transfer function G _P does not contain the hysteresis link e ^-τs , therefore, the use of the Smith predictor effectively eliminates the hysteresis link in the SCR dynamic temperature model. Therefore, the original SCR temperature control with hysteresis is offset by the Smith predictor. Therefore, when the PID closed-loop controls the SCR temperature, there will not be a large overshoot.

Based on the above method for controlling the temperature of the SCR reactor, an embodiment of the present invention also provides a device for controlling the temperature of the SCR reactor.

As shown in Figure 4, the control device of the SCR reactor temperature provided by the present invention includes:

Construct the SCR dynamic temperature model unit 41, for constructing the SCR dynamic temperature model according to the experimental test temperature before the SCR reactor and the two-point method with delay first-order inertia link fitting; the SCR dynamic temperature model contains a hysteresis link;

The first calculation unit 42 is used to calculate the compensation value according to the dynamic characteristics of the SCR dynamic temperature model, and the Smith predictor; the compensation value can eliminate the hysteresis link in the SCR dynamic temperature model;

The second calculating unit 43 is used to calculate the preset temperature of the SCR reactor minus the difference between the output of the SCR dynamic temperature model and the sum of the compensation value;

The control unit 44 is used to receive the feedback signal containing the difference, calculate the post fuel injection quantity of the engine according to the difference, and send the signal with the post fuel injection quantity of the engine to the engine, and control the engine according to The post-injection oil quantity is post-injected to control the temperature of the SCR reactor.

Through the above-mentioned control device, because the compensation value calculated by the Smith predictor can eliminate the hysteresis link in the SCR dynamic temperature model, therefore, using the above-mentioned difference as the feedback signal of the control unit will reduce the hysteresis in the SCR dynamic temperature model The link is reflected on the control unit in advance, so the exhaust gas temperature controlled by the post-injection amount obtained by the control unit 44 can reach the temperature required by the SCR reactor, so using this method to control the temperature of the SCR reactor can avoid large Overshoot phenomenon, and can also improve the response speed.

Further, in the embodiment of the present invention, the SCR dynamic temperature model includes a first-order inertia link and a hysteresis link, wherein the transfer function of the SCR dynamic temperature model can be the above-mentioned formula (1), specifically as follows:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain; T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform.

Based on the transfer function of the SCR dynamic temperature model described above, the transfer function of the Smith predictor described in the embodiment of the present invention can be the above-mentioned formula (2), specifically as follows:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

Among them, K represents the transfer function gain; T represents the time constant, and τ represents the delay time. s is the complex parameter in the Laplace transform.

Further, the control unit described above is preferably a PID controller with a Smith estimator, wherein the transfer function of the control unit can be expressed as:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Ts</span>}}<span\; class="notranslate">\; .</span>$

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. a control method of SCR reactor temperature, is characterized in that, comprises: According to the experimental test temperature before the SCR reactor and the two-point method with delayed first-order inertia link fitting, the SCR dynamic temperature model is constructed, and the SCR dynamic temperature model contains a hysteresis link; According to the dynamic characteristics of the SCR dynamic temperature model, the Smith predictor calculates the compensation value; the compensation value can eliminate the hysteresis link in the SCR dynamic temperature model; Calculating the preset temperature of the SCR reactor minus the difference between the output of the SCR dynamic temperature model and the sum of the compensation value; Receive the feedback signal containing the difference, calculate the post-injection amount of the engine according to the difference, and send the signal with the post-injection amount of the engine to the engine, and control the engine according to the post-injection amount After spraying is performed to control the temperature of the SCR reactor. 2 . The method for controlling the temperature of the SCR reactor according to claim 1 , wherein the SCR dynamic temperature model further includes a delay first-order inertia link. 3 . 3. the control method of SCR reactor temperature according to claim 2, the transfer function of described SCR dynamic temperature model is: ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ;</span>$ Among them, K represents the transfer function gain, T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform. 4. the control method of SCR reactor temperature according to claim 3 is characterized in that, the transfer function of described Smith predictor is as follows: ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$ Among them, K represents the transfer function gain, T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform. 5. The control method of SCR reactor temperature according to claim 4, is characterized in that, carries out receiving the feedback signal that contains described difference by PID controller, calculates the post-injection quantity of engine, and with described The step of sending the signal of the post-injection quantity of the engine to the engine, and controlling the engine to perform post-injection according to the post-injection quantity, so as to control the temperature of the SCR reactor. 6. A control device for SCR reactor temperature, characterized in that, comprising: Constructing an SCR dynamic temperature model unit, which is used to construct an SCR dynamic temperature model according to the experimental test temperature before the SCR reactor and a two-point method with a delayed first-order inertia link fitting; the SCR dynamic temperature model contains a hysteresis link; The first calculation unit is used to calculate the compensation value by the Smith predictor according to the dynamic characteristics of the SCR dynamic temperature model; the compensation value can eliminate the hysteresis link in the SCR dynamic temperature model; The second calculation unit is used to calculate the preset temperature of the SCR reactor minus the difference between the output of the SCR dynamic temperature model and the sum of the compensation value; The control unit is used to receive the feedback signal containing the difference, calculate the post-injection amount of the engine according to the difference, and send the signal with the post-injection amount of the engine to the engine, and control the engine to The post-injection is carried out according to the above-mentioned post-injection quantity to control the temperature of the SCR reactor. 7. the control device of SCR reactor temperature according to claim 6, is characterized in that, the transfer function of described SCR dynamic temperature model is: ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ;</span>$ Among them, K represents the transfer function gain, T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform. 8. The control device according to claim 7, wherein the transfer function of the Smith predictor is as follows: ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$ Among them, K represents the transfer function gain; T represents the time constant, τ represents the delay time, and s is a complex parameter in the Laplace transform. 9. according to the control device of the described SCR reactor temperature of claim 7 or 8 any one, it is characterized in that, described control unit is the PID controller that adds Smith predictor, and wherein, the transfer function of described control unit Expressed as: ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; Ke</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; .</span>$