CN103149837A - Sliding mode control method for methanol auto-thermal reforming hydrogen generation process - Google Patents

Abstract

The invention discloses a sliding mode control method for a methanol auto-thermal reforming hydrogen generation process, aims to solve the problem of uncertainty of model parameters of the methanol auto-thermal reforming hydrogen generation process. The sliding mode control method is independent of an accurate mathematical model of a controlled object, and a good control effect can be achieved in case of model mismatch. A sliding mode controller is used for controlling the flow of an aqueous solution of methanol, which serves as a reaction raw material, according to expected hydrogen yield, actual hydrogen yield and a change rate of the actual hydrogen yield, and in addition, a variable ratio controller capable of restricting reforming temperature is used for controlling the flow of air which serves as another reaction raw material. The method can be adapted to coupling between the uncertainty of the model parameters of the methanol auto-thermal reforming hydrogen generation process and input, and advanced control over the methanol auto-thermal reforming hydrogen generation process can be realized.

Description

The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process

Technical field

The present invention relates to the control method of methanol self-heating reforming hydrogen manufacturing process, particularly the sliding-mode control of methanol self-heating reforming hydrogen manufacturing process.

Background technology

Along with the aggravation of energy crisis, seek can substitute fossil fuels new forms of energy become a study hotspot.There is significant impact in energy problem to national economy and national development, so China also will tap a new source of energy as a strategy.

Hydrogen is considered to a kind of efficient clean energy resource.The fast development of fuel cell technology is also promoting the exploitation of Hydrogen Energy.Fuel cell is a kind of energy conversion apparatus that chemical energy is converted into electric energy.Fuel cell receives publicity because it has very high energy conversion efficiency.A most suitable fuel of fuel cell is exactly hydrogen.But due to character such as hydrogen molecule are little, inflammable and explosive, cause the storage of hydrogen and transportation to have difficulties.Methanol self-heating reforming hydrogen manufacturing technique is to be directly one of preferred version of the on-the-spot hydrogen supply of fuel cell.

The methanol self-heating reforming hydrogen manufacturing process is a complex process that relates to a plurality of chemical reactions, is a multi-input multi-output system, and model parameter has uncertainty, also exists coupling between input.In addition, fuel cell has strict requirement to the pressure of input gas, and fluctuation can cause the life-span of fuel cell and shortening fuel cell frequently.These have all brought difficulty to control, and therefore classical control algolithm is difficult to obtain good control effect.Sliding formwork is controlled because of its insensitivity to model parameter uncertainty and interference, becomes a kind of effective tool that can tackle model parameter uncertainty.

Summary of the invention

For solving the control problem of methanol self-heating reforming hydrogen manufacturing process, the invention provides a kind of sliding-mode control of methanol self-heating reforming hydrogen manufacturing process.

The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process is characterized in that adopting sliding mode controller according to expectation hydrogen output y _d, actual hydrogen output y and actual hydrogen Yield change rate x ₂Come the flow u of control response material benzenemethanol aqueous solution ₁, adopt simultaneously the no-load voltage ratio value controller with reforming temperature T constraint to handle the flow u of another reaction raw materials air ₂, concrete steps comprise:

Described sliding mode controller is by the flow u of following actual hydrogen output y and methanol aqueous solution ₁Between model handle the flow u of methanol aqueous solution ₁:

$\left\{\begin{array}{c}{\stackrel{\·}{x}}_1=x_2\\ {\stackrel{\·}{x}}_2=-a_1{x}_1-a_2{x}_2+b_1{u}_1+b_2{\stackrel{\·}{u}}_1+d\\ y=x_1\end{array}\right.---\left(1\right)$

In formula, x ₁For characterizing the state variable of actual hydrogen output,

Be x ₁Derivative;

Be x ₂Derivative;

Be u ₁Derivative; D is for disturbing, and its absolute value is less than or equal to the higher limit d that disturbs _M Be x ₁, x ₂, u ₁,

With the linear function of d, a ₁, a ₂, b ₁, b ₂Positive coefficient for described linear function.

In described sliding mode controller, the definition error e ₁And error e ₂For

$\left\{\begin{array}{c}{e}_1=x_1-y_d\\ e_2=x_2-{\stackrel{\·}{y}}_d\end{array}\right.---\left(2\right)$

In formula,

Be y _dDerivative.

In described sliding mode controller, select switching function s to be

s=ce ₁+e ₂ (3)

In formula, c is the coefficient greater than 0.

In described sliding mode controller, the flow u of methanol aqueous solution ₁Derivative

For

${\stackrel{\·}{u}}_1=\mathrm{\α}{e}_1+{\mathrm{\βe}}_2+{\widehat{\mathrm{\θ}}}^{T}Z-\mathrm{\δsgn}\left(s\right)---\left(4\right)$

In formula,

For $\mathrm{\θ}=\frac{1}{b_2}{\left[\begin{array}{cccc}{a}_1& a_2& 1& {-b}_1\end{array}\right]}^T$ Estimated value; $Z={\left[\begin{array}{cccc}{y}_d& {\stackrel{\·}{y}}_d& {\stackrel{\begin{array}{cc}\·& \·\end{array}}{y}}_d& u_1\end{array}\right]}^T,$ Wherein

Be y _dSecond derivative;

B wherein _2mLess than or equal to b ₂Positive number; Sgn (s) is sign function; α and β satisfy following condition:

$\mathrm{\&alpha;}=\left\{\begin{array}{c}{\mathrm{\&alpha;}}_1<\min \left\{\frac{a_1}{b_2}\right\},e_{1}s>0\\ {\mathrm{\&alpha;}}_2>\max \left\{\frac{a_1}{b_2}\right\},e_{1}s<0\end{array}\right.---\left(5\right)$

$\mathrm{\&beta;}=\left\{\begin{array}{c}{\mathrm{\&beta;}}_1<\min \left\{\frac{a_2-c}{b_2}\right\},e_{2}s>0\\ {\mathrm{\&beta;}}_2>\max \left\{\frac{a_2-c}{b_2}\right\},e_{2}s<0\end{array}\right.---\left(6\right)$

Update rule be

$\stackrel{\&CenterDot;}{\widehat{\mathrm{\&theta;}}}=-\mathrm{sRZ}$

$R=\left[\begin{array}{cccc}{r}_1& 0& 0& 0\\ 0& r_2& 0& 0\\ 0& 0& r_3& 0\\ 0& 0& 0& r_4\end{array}\right]---\left(7\right)$

In formula, For

Derivative; r ₁, r ₂, r ₃, r ₄For greater than 0 coefficient.

In described no-load voltage ratio value controller, the flow u of air ₂Flow u with methanol aqueous solution ₁Ratio be K, namely

u ₂=K(n)u ₁ (8)

In formula, K (n) is the flow u of n sampling period air ₂Flow u with methanol aqueous solution ₁Ratio; The value of K (n) is upgraded according to reforming temperature T, and K when reforming temperature T is higher (n) reduces, and K when reforming temperature T is on the low side (n) increases.

The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process is characterized in that with High-gain observer actual hydrogen Yield change rate x ₂Estimate, obtain actual hydrogen Yield change rate x ₂Estimated value Described High-gain observer is

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{\hat{x}}}_1={\hat{x}}_2+p_{1}k(y-\hat{y})\\ {\stackrel{\&CenterDot;}{\hat{x}}}_2=p_2{k}^2(y-\hat{y})\\ \hat{y}={\hat{x}}_1\end{array}\right.---\left(9\right)$

In formula,

Be actual hydrogen output x ₁Estimated value,

For

Derivative; For

Derivative;

Estimated value for y; K is observer gain; p ₁, p ₂Be coefficient, value must satisfy following equation

z ²+p ₁z+p ₂=0 (10)

Have different, wherein z is the unknown number of described equation.

The invention has the beneficial effects as follows, a kind of sliding-mode control of methanol self-heating reforming hydrogen manufacturing process is provided.For the model parameter uncertainty of methanol self-heating reforming hydrogen manufacturing process, the sliding formwork of utilization of the present invention is controlled the mathematical models that does not rely on controlled device, and this makes control method when model mismatch, still can obtain good control effect.The present invention adopts described sliding mode controller according to expectation hydrogen output y _d, actual hydrogen output y and actual hydrogen Yield change rate x ₂Come the flow u of control response material benzenemethanol aqueous solution ₁, adopt simultaneously described no-load voltage ratio value controller with reforming temperature T constraint to handle the flow u of another reaction raw materials air ₂The present invention can adapt to the model parameter uncertainty of methanol self-heating reforming hydrogen manufacturing process and the coupling between input, realizes the advanced person of methanol self-heating reforming hydrogen manufacturing process is controlled.

Description of drawings

Fig. 1 is the control block diagram of methanol self-heating reforming hydrogen manufacturing process corresponding to the present invention.

Embodiment

The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process is with the flow u of reaction raw materials methanol aqueous solution ₁Flow u with another reaction raw materials air ₂Be manipulated variable, take hydrogen output y and reforming temperature T as controlled variable.

The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process is characterized in that adopting sliding mode controller according to expectation hydrogen output y _d, actual hydrogen output y and actual hydrogen Yield change rate x ₂Come the flow u of control response material benzenemethanol aqueous solution ₁, adopt simultaneously the no-load voltage ratio value controller with reforming temperature T constraint to handle the flow u of another reaction raw materials air ₂, concrete steps comprise:

In described methanol aqueous solution, the mol ratio of water and methyl alcohol is generally (1.0 ~ 1.5): 1, and the present embodiment adopts 1.2:1.

The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process is characterized in that adopting sliding mode controller according to expectation hydrogen output y _d, actual hydrogen output y and actual hydrogen Yield change rate x ₂Come the flow u of control response material benzenemethanol aqueous solution ₁, adopt simultaneously the no-load voltage ratio value controller with reforming temperature T constraint to handle the flow u of another reaction raw materials air ₂, concrete steps comprise:

Described sliding mode controller is by the flow u of following actual hydrogen output y and methanol aqueous solution ₁Between model handle the flow u of methanol aqueous solution ₁:

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{x}}_1=x_2\\ {\stackrel{\&CenterDot;}{x}}_2=-a_1{x}_1-a_2{x}_2+b_1{u}_1+b_2{\stackrel{\&CenterDot;}{u}}_1+d\\ y=x_1\end{array}\right.---\left(1\right)$

In formula, x ₁For characterizing the state variable of actual hydrogen output,

Be x ₁Derivative;

Be x ₂Derivative;

Be u ₁Derivative; D is for disturbing, and its absolute value is less than or equal to the higher limit d that disturbs _M Be x ₁, x ₂, u ₁,

With the linear function of d, a ₁, a ₂, b ₁, b ₂Be the positive coefficient of described linear function, positive coefficient a ₁, a ₂, b ₁, b ₂Value test acquisition by System Discrimination.

In described sliding mode controller, the definition error e ₁And error e ₂For

$\left\{\begin{array}{c}{e}_1=x_1-y_d\\ e_2=x_2-{\stackrel{\&CenterDot;}{y}}_d\end{array}\right.---\left(2\right)$

In formula,

Be y _dDerivative.

In described sliding mode controller, select switching function s to be

s=ce ₁+e ₂ (3)

In formula, c is the coefficient greater than 0.

In described sliding mode controller, the flow u of methanol aqueous solution ₁Derivative

For

${\stackrel{\&CenterDot;}{u}}_1=\mathrm{\&alpha;}{e}_1+\mathrm{\&beta;}{e}_2+{\widehat{\mathrm{\&theta;}}}^{T}Z-\mathrm{\&delta;sgn}\left(s\right)---\left(4\right)$

In formula,

For $\mathrm{\&theta;}=\frac{1}{b_2}{\left[\begin{array}{cccc}{a}_1& a_2& 1& {-b}_1\end{array}\right]}^T$ Estimated value; $Z={\left[\begin{array}{cccc}{y}_d& {\stackrel{\&CenterDot;}{y}}_d& {\stackrel{\begin{array}{cc}\&CenterDot;& \&CenterDot;\end{array}}{y}}_d& u_1\end{array}\right]}^T,$ Wherein

Be y _dSecond derivative;

B wherein _2mLess than or equal to b ₂Positive number; Sgn (s) is sign function; α and β satisfy following condition:

$\mathrm{\&alpha;}=\left\{\begin{array}{c}{\mathrm{\&alpha;}}_1<\min \left\{\frac{a_1}{b_2}\right\},e_{1}s>0\\ {\mathrm{\&alpha;}}_2>\max \left\{\frac{a_1}{b_2}\right\},e_{1}s<0\end{array}\right.---\left(5\right)$

$\mathrm{\&beta;}=\left\{\begin{array}{c}{\mathrm{\&beta;}}_1<\min \left\{\frac{a_2-c}{b_2}\right\},e_{2}s>0\\ {\mathrm{\&beta;}}_2>\max \left\{\frac{a_2-c}{b_2}\right\},e_{2}s<0\end{array}\right.---\left(6\right)$

Update rule be

$\stackrel{\&CenterDot;}{\widehat{\mathrm{\&theta;}}}=-\mathrm{sRZ}$

$R=\left[\begin{array}{cccc}{r}_1& 0& 0& 0\\ 0& r_2& 0& 0\\ 0& 0& r_3& 0\\ 0& 0& 0& r_4\end{array}\right]---\left(7\right)$

In formula,

For

Derivative; r ₁, r ₂, r ₃, r ₄For greater than 0 coefficient.

Described sliding formwork is controlled in controller coefficient c, α, and β and R, there is impact in they to performance.

C major effect dynamic property.The value of c is larger, and dynamic responding speed is faster, but the variation of manipulated variable also Shaoxing opera is strong, also higher to the requirement of actuator.Therefore, the value of c need to consider the requirement of dynamic property and the ability of actuator are set.

α and β major effect dynamic property.The absolute value of α and β is larger, and dynamic responding speed is faster, but the amplitude that manipulated variable changes also greatly, even exceeds the scope of actuator.Therefore, the value of α and β also needs to consider the requirement of dynamic property and the ability of actuator is set.

R is arranged in R ₁, r ₂, r ₃, r ₄, be respectively

The correction coefficient of each component.Correction coefficient is larger, and correction rate is faster, proofreaies and correct the too fast over-control that has.Therefore, r ₁, r ₂, r ₃, r ₄Value also need to set according to actual conditions.In addition, also need to set

Initial value, suitable initial value can allow Convergence and converge on its true value promptly.

In described no-load voltage ratio value controller, the flow u of air ₂Liter/min clock) and the flow u of methanol aqueous solution (unit: ₁(unit: ratio ml/min) is K, namely

u ₂=K(n)u ₁ (8)

In formula, K (n) is the flow u of n sampling period air ₂Flow u with methanol aqueous solution ₁Ratio; The value of K (n) is according to reforming temperature T(unit: degree centigrade) upgrade, K when reforming temperature T is higher (n) reduces, and K when reforming temperature T is on the low side (n) increases.The update rule that the present embodiment adopts is

K(n)=K(n-1)+ΔK

$\mathrm{\&Delta;K}=\left\{\begin{array}{c}-0.015,T>550\\ 0.015,T<510\\ \mathrm{0,510}\&le;T\&le;550\end{array}\right.$

The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process is characterized in that with High-gain observer actual hydrogen Yield change rate x ₂Estimate, obtain actual hydrogen Yield change rate x ₂Estimated value

Described High-gain observer is

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{\hat{x}}}_1={\hat{x}}_2+p_{1}k(y-\hat{y})\\ {\stackrel{\&CenterDot;}{\hat{x}}}_2=p_2{k}^2(y-\hat{y})\\ \hat{y}={\hat{x}}_1\end{array}\right.---\left(9\right)$

In formula, Be actual hydrogen output x ₁Estimated value,

For

Derivative;

For

Derivative;

Estimated value for y; K is observer gain; p ₁, p ₂Be coefficient, value must satisfy following equation

z ²+p ₁z+p ₂=0 (10)

Have different, wherein z is the unknown number of described equation.

The control block diagram of the methanol self-heating reforming hydrogen manufacturing process that the present invention is corresponding as shown in Figure 1.The sliding-mode control of methanol self-heating reforming hydrogen manufacturing process adopts sliding mode controller according to expectation hydrogen output y _d, actual hydrogen output y and actual hydrogen Yield change rate x ₂Estimated value

Come the flow u of control response material benzenemethanol aqueous solution ₁, adopt simultaneously the no-load voltage ratio value controller with reforming temperature T constraint to handle the flow u of another reaction raw materials air ₂

Above-mentioned embodiment is used for the present invention that explains; be only the preferred embodiments of the present invention; rather than limit the invention; in the protection domain of spirit of the present invention and claim; any modification that the present invention is made, be equal to replacement, improvement etc., all fall into protection scope of the present invention.

Claims (2)

1. the sliding-mode control of methanol self-heating reforming hydrogen manufacturing process, is characterized in that adopting sliding mode controller according to expectation hydrogen output y _d, actual hydrogen output y and actual hydrogen Yield change rate x ₂Come the flow u of control response material benzenemethanol aqueous solution ₁, adopt simultaneously the no-load voltage ratio value controller with reforming temperature T constraint to handle the flow u of another reaction raw materials air ₂, concrete steps comprise:

Described sliding mode controller is by the flow u of following actual hydrogen output y and methanol aqueous solution ₁Between model handle the flow u of methanol aqueous solution ₁:

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{x}}_1=x_2\\ {\stackrel{\&CenterDot;}{x}}_2=-a_1{x}_1-a_2{x}_2+b_1{u}_1+b_2{\stackrel{\&CenterDot;}{u}}_1+d\\ y=x_1\end{array}\right.---\left(1\right)$

In formula, x ₁For characterizing the state variable of actual hydrogen output,

Be x ₁Derivative;

Be x ₂Derivative;

Be u ₁Derivative; D is for disturbing, and its absolute value is less than or equal to the higher limit d that disturbs _M

Be x ₁, x ₂, u ₁,

With the linear function of d, a ₁, a ₂, b ₁, b ₂Positive coefficient for described linear function.

In described sliding mode controller, the definition error e ₁And error e ₂For

$\left\{\begin{array}{c}{e}_1=x_1-y_d\\ e_2=x_2-{\stackrel{\&CenterDot;}{y}}_d\end{array}\right.---\left(2\right)$

In formula, Be y _dDerivative.

In described sliding mode controller, select switching function s to be

s=ce ₁+e ₂ (3)

In formula, c is the coefficient greater than 0.

In described sliding mode controller, the flow u of methanol aqueous solution ₁Derivative

For

${\stackrel{\&CenterDot;}{u}}_1=\mathrm{\&alpha;}{e}_1+\mathrm{\&beta;}{e}_2+{\widehat{\mathrm{\&theta;}}}^{T}Z-\mathrm{\&delta;sgn}\left(s\right)---\left(4\right)$

In formula,

For $\mathrm{\&theta;}=\frac{1}{b_2}{\left[\begin{array}{cccc}{a}_1& a_2& 1& {-b}_1\end{array}\right]}^T$ Estimated value; $Z={\left[\begin{array}{cccc}{y}_d& {\stackrel{\&CenterDot;}{y}}_d& {\stackrel{\begin{array}{cc}\&CenterDot;& \&CenterDot;\end{array}}{y}}_d& u_1\end{array}\right]}^T,$ Wherein Be y _dSecond derivative;

B wherein _2mLess than or equal to b ₂Positive number; Sgn (s) is sign function; α and β satisfy following condition:

$\mathrm{\&alpha;}=\left\{\begin{array}{c}{\mathrm{\&alpha;}}_1<\min \left\{\frac{a_1}{b_2}\right\},e_{1}s>0\\ {\mathrm{\&alpha;}}_2>\max \left\{\frac{a_1}{b_2}\right\},e_{1}s<0\end{array}\right.---\left(5\right)$

$\mathrm{\&beta;}=\left\{\begin{array}{c}{\mathrm{\&beta;}}_1<\min \left\{\frac{a_2-c}{b_2}\right\},e_{2}s>0\\ {\mathrm{\&beta;}}_2>\max \left\{\frac{a_2-c}{b_2}\right\},e_{2}s<0\end{array}\right.---\left(6\right)$

Update rule be

$\stackrel{\&CenterDot;}{\widehat{\mathrm{\&theta;}}}=-\mathrm{sRZ}$

$R=\left[\begin{array}{cccc}{r}_1& 0& 0& 0\\ 0& r_2& 0& 0\\ 0& 0& r_3& 0\\ 0& 0& 0& r_4\end{array}\right]---\left(7\right)$

In formula,

For Derivative; r ₁, r ₂, r ₃, r ₄For greater than 0 coefficient.

In described no-load voltage ratio value controller, the flow u of air ₂Flow u with methanol aqueous solution ₁Ratio be K, namely

u ₂=K(n)u ₁ (8)

In formula, K (n) is the flow u of n sampling period air ₂Flow u with methanol aqueous solution ₁Ratio; The value of K (n) is upgraded according to reforming temperature T, and K when reforming temperature T is higher (n) reduces, and K when reforming temperature T is on the low side (n) increases.

2. the sliding-mode control of methanol self-heating reforming hydrogen manufacturing process as claimed in claim 1, is characterized in that described actual hydrogen Yield change rate x ₂Adopt High-gain observer to estimate, obtain described actual hydrogen Yield change rate x ₂Estimated value

Described High-gain observer is

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{\hat{x}}}_1={\hat{x}}_2+p_{1}k(y-\hat{y})\\ {\stackrel{\&CenterDot;}{\hat{x}}}_2=p_2{k}^2(y-\hat{y})\\ \hat{y}={\hat{x}}_1\end{array}\right.---\left(9\right)$

In formula,

Be actual hydrogen output x ₁Estimated value,

For

Derivative;

For

Derivative;

Estimated value for y; K is observer gain; p ₁, p ₂Be coefficient, value must satisfy following equation

z ²+p ₁z+p ₂=0 (10)

Have different, wherein z is the unknown number of described equation.

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