CN103134046B - Superheated steam temperature two-stage coordination, prediction and control method of thermal power generating unit - Google Patents

Abstract

The invention discloses a superheated steam temperature two-stage coordination, prediction and control method of a thermal power generating unit. The method designs a two-stage coordination and control algorithm and utilizes a GPC-P (generalized predictive control-proportion) cascade control strategy to respectively achieve the control of first-stage and second-stage desuperheating water spraying and enable the two-stage desuperheating water control to approximately decouple under the situation that a second-stage desuperheating water valve has adjusting allowance, accordingly the adjusting process of the first-stage desuperheating water spraying cannot cause the temperature fluctuation of the outlet of a last-stage superheater; and when the second-stage desuperheating water valve reaches an upper limit or a lower limit, makes full use of the adjusting allowance of the first-stage desuperheating water spraying to assist the second-stage desuperheating water spraying to control superheated steam temperature, and further reduces the deviation between a dynamic state and a steady state of the superheated steam temperature control, thereby improving the control performance of a system.

Description

A kind of fired power generating unit overheating steam temperature two-stage predictive coordinated control method

Technical field

The invention belongs to thermal technology's automation field, relate in particular to a kind of optimal control method of Super-heated Steam Temperature System, more specifically a kind of fired power generating unit overheating steam temperature two-stage predictive coordinated control method.

Background technology

Overheating steam temperature is directly connected to security and the economy of thermal power unit operation, is one of procedure parameter needing in unit running process key monitoring.

Because superheater pipeline is longer, there is larger inertia and delay in steam temperature controlled device, causes traditional control method to be often difficult to obtain satisfied control effect.In addition, the Super-heated Steam Temperature System of modern large electric power plant unit is generally all provided with two-stage or direct-contact desuperheater more than two-stage, and this has wherein just had the Harmonic Control between level and level naturally.Obviously primary superheater outlet temperature, as the inlet temperature of two-stage superheater, will finally have influence on overheating steam temperature.In actual super-heated steam temperature control, often there is following situation: main stripping temperature is closed lower than setting value and secondary desuperheat water spray valve sometimes, but one-level desuperheat water spray valve is also in opening; Sometimes main steam temperature has reached maximum higher than setting value and secondary desuperheat water spray valve, but one-level desuperheat water spray valve regulates the situations such as surplus in addition.In above situation, although secondary attemperation control device has lost regulating action, can regulate main stripping temperature to arrive setting value by adjusting primary superheater outlet temperature.Obviously for above-mentioned situation, need to, by the control of two-stage spray desuperheating, organize according to certain rule, co-ordination, brings into play the effect of two-stage spray desuperheating control to greatest extent, further improves the regulation quality of overheating steam temperature.

Current most fired power generating unit Superheated Steam Temperature Control System Applied still adopts conventional PID (proportional-integral-differential) Cascade Control Plan, be difficult to successfully manage that steam temperature object has delays greatly characteristic, also do not take into full account the coordination problem of two-stage water spray between controlling simultaneously.

Summary of the invention

Goal of the invention: the problem and shortage existing for above-mentioned prior art, the object of this invention is to provide a kind of fired power generating unit overheating steam temperature two-stage predictive coordinated control method, can further reduce dynamic deviation and static deviation that overheating steam temperature regulates, improve the regulation quality of overheating steam temperature.

Technical scheme: for achieving the above object, the technical solution used in the present invention is a kind of fired power generating unit overheating steam temperature two-stage predictive coordinated control method, comprises the steps:

(1), under steady state condition, firsts and seconds desuperheat spray water control system is switched to manual mode, and carries out respectively desuperheating water valve step response test;

(2) utilize two-point method to obtain respectively the transfer function of following object: the transfer function W of one-level leading steam temperature to one-level desuperheating water valve opening ₁₁(s) (DEG C/%); The transfer function W of First stage steam to one-level desuperheating water valve opening ₁(s) (DEG C/%); The transfer function W of overheating steam temperature to one-level desuperheating water valve opening ₃(s) (DEG C/%); The transfer function W of secondary leading steam temperature to secondary desuperheating water valve opening ₂₁(s) (DEG C/%); And the transfer function W of overheating steam temperature to secondary desuperheating water valve opening ₂(s) (DEG C/%);

(3) utilize Series Expansion Method to ask the transfer function W of overheating steam temperature to First stage steam _d(s) (DEG C/DEG C), the transfer function W of First stage steam to one-level leading steam temperature ₁₂(s) (DEG C/DEG C), and the transfer function W of overheating steam temperature to secondary leading steam temperature ₂₂(s) (DEG C/DEG C); Because W ₃(s)=W _d(s) W ₁, and W (s) ₁and W (s) ₃(s) be known, therefore utilize " Series Expansion Method " can try to achieve W _d(s); In like manner can try to achieve the transfer function W of First stage steam to one-level leading steam temperature ₁₂(s) (DEG C/DEG C), and the transfer function W of overheating steam temperature to secondary leading steam temperature ₂₂(s) (DEG C/DEG C);

(4), in each control cycle, the one-level of utilizing two-stage to coordinate control algolithm calculating current time is coordinated signal O ₁(k) and secondary coordinate signal O ₂(k);

(5) utilize one-level to coordinate signal O ₁(k), by formula (1), First stage steam is set value to T _sp1(k) revise, correction result is T ' _sp1(k):

T′ _sp1(k)＝T _sp1(k)+O ₁(k) (1)

And secondary is coordinated to signal O ₂(k) be incorporated into secondary GPC controller as feed-forward signal;

(6) utilize one-level to coordinate signal O ₁(k) and series connection one-level GPC controller and the controlled quentity controlled variable u of one-level proportional controller first order calculation desuperheating water valve ₁(k) also output, utilizes secondary to coordinate signal O ₂(k) and the secondary GPC controller of series connection and secondary proportional controller calculate the controlled quentity controlled variable u of secondary desuperheating water valve ₂(k) also output.

Further, in described step (4):

If Z ₂(k)=0 and T ₂(k) <T _sp2and Z (k) ₁(k) >0, or, Z ₂(k)=100 and T ₂(k) >T _sp2and Z (k) ₁(k) <100, O ₁(k)=α e ₂and O (k) ₂(k)=0, otherwise O ₁(k)=0 and O ₂(k)=Δ T ₁(k),

Wherein, Z ₁and Z (k) ₂(k) be respectively firsts and seconds desuperheating water valve position feedback signal; T ₂(k) be overheating steam temperature measuring-signal; T _sp2(k) be overheating steam temperature setting value; O ₁(k) coordinate the output signal of control algolithm to one-level attemperation control for two-stage, it is added on the duty setting signal of First stage steam; O ₂(k) coordinate the output signal of control algolithm to secondary attemperation control for two-stage, it is as an input signal of secondary GPC controller; e ₂(k)=T _sp2(k)-T ₂(k) be secondary super-heated steam temperature control deviation; α is two-stage cooperation index, conventionally gets α=0.8; Δ T ₁(k) be the variable quantity of First stage steam.

Further, described step (6) comprises the steps:

1. for W ₁₁and W (s) ₂₁(s), utilize the attenuation curve method firsts and seconds proportional controller parameter K of adjusting respectively ₁and K ₂, wherein K ₁and K ₂all be less than 0, and ask respectively the transfer function W of firsts and seconds GPC controller equivalence controlled device ₀₁and W (s) ₀₂(s), wherein, W ₀₁(s)=(K ₁w ₁₁(s) W ₁₂(s))/(1+K ₁w ₁₁(s)), W ₀₂(s)=(K ₂w ₂₁(s) W ₂₂(s))/(1+K ₂w ₂₁(s));

2. firsts and seconds GPC controller relevant parameter is set, comprises sampling time T _s, prediction step number N, controls step number N _u, output error weight matrix Q, and control matrix R;

3. for overheating steam temperature setting value T _sp2(k) calculate the output of secondary GPC controller;

4. calculate the controlled quentity controlled variable u of secondary desuperheating water valve ₂(k) also output;

5. for revised First stage steam setting value T ' _sp1(k) first order calculation GPC controller output;

6. the controlled quentity controlled variable u of first order calculation desuperheating water valve ₁(k) also output.

Beneficial effect: compared with prior art, the present invention has the following advantages: in the situation that secondary desuperheating water valve exists adjusting surplus, two-stage is coordinated control algolithm makes firsts and seconds desuperheat water spray control Approximate Decoupling, therefore the adjustment process of one-level desuperheat water spray, can not cause the fluctuation of finishing superheater outlet temperature; And at secondary desuperheating water valve in the situation that up/down is limit, this algorithm can make full use of the adjusting surplus of one-level water spray, assists secondary water spray to control overheating steam temperature.The method can effectively improve the control accuracy of overheating steam temperature, further reduces control deviation.

Brief description of the drawings

Fig. 1 is fired power generating unit overheating steam temperature two-stage predictive coordinated control system construction drawing of the present invention.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, further illustrate the present invention, should understand these embodiment is only not used in and limits the scope of the invention for the present invention is described, after having read the present invention, those skilled in the art all fall within the application's claims limited range to the amendment of the various equivalent form of values of the present invention.

Fired power generating unit overheating steam temperature two-stage predictive coordinated control method of the present invention, coordinate control algolithm by design two-stage, and adopt GPC-P (Generalized Prediction-ratio) cascade control strategy to realize respectively the control to firsts and seconds desuperheat water spray, make the co-ordination of two-stage water spray, that effectively processes steam temperature object delays greatly characteristic simultaneously, further improves the regulation quality of overheating steam temperature.Described two-stage predictive coordinated control method concrete steps are as follows:

(1), under steady state condition, firsts and seconds desuperheat spray water control system is switched to manual mode, and carries out respectively desuperheating water valve step response test.

(2) utilize two-point method to obtain respectively the transfer function of following object: the transfer function W of one-level leading steam temperature to one-level desuperheating water valve opening ₁₁(s) (DEG C/%); The transfer function W of First stage steam to one-level desuperheating water valve opening ₁(s) (DEG C/%); The transfer function W of overheating steam temperature to one-level desuperheating water valve opening ₃(s) (DEG C/%); The transfer function W of secondary leading steam temperature to secondary desuperheating water valve opening ₂₁(s) (DEG C/%); The transfer function W of overheating steam temperature to secondary desuperheating water valve opening ₂(s) (DEG C/%).

(3) ask the transfer function W of overheating steam temperature to First stage steam _d(s) (DEG C/DEG C).Because W ₃(s)=W _d(s) W ₁, and W (s) ₁and W (s) ₃(s) be known, therefore utilize " Series Expansion Method " can try to achieve W _d(s).In like manner can try to achieve the transfer function W of First stage steam to one-level leading steam temperature ₁₂(s) (DEG C/DEG C), and the transfer function W of overheating steam temperature to secondary leading steam temperature ₂₂(s) (DEG C/DEG C).

(4), in each control cycle, the two-stage of utilizing two-stage to coordinate control algolithm calculating current time is coordinated signal O ₁(k) (one-level coordination signal) and O ₂(k) (secondary coordination signal).In accompanying drawing 1, f ₁and f (x) ₂(x) be the function of load, for generating the duty setting signal of different load next stage steam temperature and overheating steam temperature.

The basic thought that two-stage is coordinated to control is: adopt different control strategies according to concrete conditions such as overheating steam temperature adjusting deviation, firsts and seconds desuperheating water valve locations, in the situation that there is adjusting surplus in secondary desuperheating water valve, the adjusting task of Ying Youqi complete independently to overheating steam temperature, change the impact on overheating steam temperature for eliminating First stage steam simultaneously, should, by design two-stage decoupling zero loop, make the control of two-stage desuperheating water realize Approximate Decoupling; Limit in up/down at secondary desuperheating water valve in addition, and main stripping temperature still can not meet the demands, one-level desuperheating water valve exists in the situation that regulates surplus simultaneously, should cancel two-stage decoupling zero loop, super-heated steam temperature control deviation is multiplied by after certain coefficient simultaneously, in the setting value of First stage steam of being added to, thereby make one-level desuperheat water spray participate in the adjusting to overheating steam temperature directly, utilize it to regulate surplus further to reduce super-heated steam temperature control deviation.

Can obtain following two-stage according to above-mentioned thought and coordinate control algolithm:

If Z ₂(k)=0 and T ₂(k) <T _sp2and Z (k) ₁(k) >0, or, Z ₂(k)=100 and T ₂(k) >T _sp2and Z (k) ₁(k) <100,

O so ₁(k)=α e ₂and O (k) ₂(k)=0,

Otherwise

O ₁(k)=0 and O ₂(k)=Δ T ₁(k)

Wherein, Z ₁and Z (k) ₂(k) be firsts and seconds desuperheating water valve position feedback signal; T ₂(k) be overheating steam temperature measuring-signal; T _sp2(k) be overheating steam temperature setting value; O ₁(k) coordinate the output signal (be one-level coordinate signal) of control algolithm to one-level attemperation control for two-stage, it is added on the duty setting signal of First stage steam; O ₂(k) coordinate the output signal (be secondary coordinate signal) of control algolithm to secondary attemperation control for two-stage, it is as an input signal of secondary attemperation control device; e ₂(k)=T _sp2(k)-T ₂(k) be secondary super-heated steam temperature control deviation; α is two-stage cooperation index, conventionally gets α=0.8; Δ T ₁(k) be the variable quantity of First stage steam.

(5) utilize two-stage to coordinate signal O ₁(k), by formula (1), First stage steam is set value to T _sp1(k) revise, and O ₂(k) be incorporated into secondary GPC controller as feed-forward signal.

T′ _sp1(k)＝T _sp1(k)+O ₁(k) (1)

(6) utilize two-stage to coordinate the control output u of signal and GPC-P tandem control algolithm difference first order calculation and secondary desuperheating water valve ₁and u (k) ₂(k).

Above-mentioned two-stage is coordinated control algolithm requirement, in the situation that secondary desuperheating water valve exists adjusting surplus, makes the control of two-stage desuperheating water realize Approximate Decoupling.How can both meet this requirement, that effectively processes again steam temperature object delays greatly characteristic simultaneously, is finally to realize two-stage to coordinate to control and need a key issue solving.The present invention adopts the GPC-P tandem control algolithm with feedforward compensation, by setting up the disturbance channel pattern of First stage steam to overheating steam temperature, naturally in secondary desuperheat PREDICTIVE CONTROL, introduce the feedforward compensation of First stage steam, thereby realize the Approximate Decoupling between two-stage water spray is controlled, that can process well again steam temperature object delays greatly characteristic simultaneously, has therefore solved preferably this problem.Because the control of firsts and seconds desuperheat water spray all adopts GPC-P cascade control strategy, both design processes are basic identical, and therefore emphasis describes as an example of secondary attemperation control example below.Concrete steps are:

1. for W ₂₁(s), utilize the attenuation curve method secondary proportional controller parameter K of adjusting of adjusting ₂(negative value), and ask the transfer function W of homophony control channel equivalence controlled device ₀₂(s)=(K ₂w ₂₁(s) W ₂₂(s))/(1+K ₂w ₂₁(s)).

2. GPC controller relevant parameter is set, comprises sampling time T _s, prediction step number N, controls step number N _u, output error weight matrix Q, control matrix R.Get T _s/ T ₉₅=1/15, wherein, T ₉₅for W ₀₂(s) transient process rises to for 95% adjusting time.N elects as and is approximately equal to W ₀₂(s) rise time of step response; N _uselect 1 or 2; Q=diag (q ₁..., q _n), wherein, q ₁..., q _nwith for corresponding weight coefficient.

3. calculate the output of secondary GPC controller.

By W ₀₂and W (s) _d(s) must be with the overheating steam temperature CARIMA model of disturbance term, shown in (2) after discretization.

$A\left(q^{-1}\right)T_2\left(k\right)=B\left(q^{-1}\right)u(k-1)+\frac{\mathrm{\&xi;}\left(k\right)}{\mathrm{\&Delta;}}+D\left(q^{-1}\right)T_1\left(k\right)---\left(2\right)$

In formula: u (k-1) is the subloop setting value of k-1 moment secondary homophony GPC controller output; ξ (k) is random disturbances; q ^-1be backward shift operator, subscript-1 is moved one after representing, after-i represents, moves i position; Δ=1-q ^-1; $A\left(q^{-1}\right)=1+\underset{i=1}{\overset{n_a}{\mathrm{\&Sigma;}}}{a}_i{q}^{-i};B\left(q^{-1}\right)=\underset{i=0}{\overset{n_b}{\mathrm{\&Sigma;}}}{b}_i{q}^{-i};D\left(q^{-1}\right)=\underset{i=1}{\overset{n_d}{\mathrm{\&Sigma;}}}{d}_i{q}^i;$ Wherein, n _a, n _band n _dbe respectively multinomial A (q ^-1), B (q ^-1) and D (q ^-1) order, a _i, b _iand d _ibe respectively the coefficient of corresponding polynomial.Notice that formula has increased last in (2), i.e. the disturbance term of First stage steam compared with conventional GPC algorithm.

By formula (2) and introduce Diophantine equation 1=E _j(q ^-1) A (q ^-1) Δ+q ^-jf _j(q ^-1), must be with the overheating steam temperature forecast model of disturbance term, suc as formula (3):

T ₂(k+j|k)＝G _j(q ^-1)Δu(k+j-1|k)+H _j(q ^-1)ΔT ₁(k+j-1)+F _j(q ^-1)T ₂(k),j＝1,…,N

(3)

In formula, T ₂(k+j|k) be the predicted value of the Given information that utilizes the k moment overheating steam temperature to the following k+j moment; Δ u (k+j-1|k) is the estimated value of k+j-1 moment controlling increment; Δ T ₁(k+j-1) be the variable quantity of k+j-1 moment First stage steam; Multinomial $G_j\left(q^{-1}\right)=E_j\left(q^{-1}\right)B\left(q^{-1}\right)=\underset{i=0}{\overset{n_b+j-1}{\mathrm{\&Sigma;}}}{g}_{j,i}{q}^{-i};$

$H_j\left(q^{-1}\right)=E_j\left(q^{-1}\right)D\left(q^{-1}\right)=\underset{i=0}{\overset{n_d+j-1}{\mathrm{\&Sigma;}}}{h}_{j,i}{q}^{-i}{;E}_j\left(q^{-1}\right)=\underset{i=0}{\overset{j-1}{\mathrm{\&Sigma;}}}{e}_{j,i}{q}^{-i};F_j\left(q^{-1}\right)=\underset{i=0}{\overset{n_a}{\mathrm{\&Sigma;}}}{f}_{j,i}{q}^{-i},$ Wherein g _j,i, h _j,i, e _j,iand f _j,iit is respectively the coefficient of the i time item of corresponding polynomial while predicting forward j step.E _j(q ^-1) and F _j(q ^-1) can use formula (4) recursion to calculate:

$\left\{\begin{array}{c}{f}_{j+1}=\tilde{A}{f}_j,f_0={\left[\begin{array}{cccc}1& 0& ...& 0\end{array}\right]}^T\\ E_{j+1}=E_j+f_{j,0}{q}^{-j},E_0=0\end{array}\right.----\left(4\right)$

In formula, $f_j={\left[\begin{array}{ccc}{f}_{j,0}& ...& f_{j,n_a}\end{array}\right]}^T.$

If Δ u (k+j-1|k)=0, j > N _u, formula (3) can be expressed as by vector form:

${\tilde{T}}_P\left(k\right)=G\&CenterDot;\mathrm{\&Delta;U}\left(k\right)+z\left(k\right)+H\&CenterDot;\mathrm{\&Delta;}{\tilde{T}}_1\left(k\right)---\left(5\right)$

In formula, ${\tilde{T}}_P\left(k\right)={[T_2(k+1|k),...,T_2(k+N|k)]}^T;$

ΔU(k)＝[Δu(k|k) ,…, Δu(k+N _u-1|k)] ^T；

$\mathrm{\&Delta;}{\tilde{T}}_1\left(k\right)={\left[\begin{array}{ccc}\mathrm{\&Delta;}{T}_1\left(k\right)& ,...,& \mathrm{\&Delta;}{T}_1(k+N-1)\end{array}\right]}^T;$

z(k)＝[z ₁(k),z ₂(k) ,…, z _N(k)] ^T；

z _j(k)＝q ^j-1[G _j(q ^-1)-q ^-(j-1)g _j,j-1-,…,-g _j,0]·Δu(k|k)+F _j(q ^-1)·T ₂(k),j＝1,2,…,N。

Because the variable quantity of following moment First stage steam is unknown, therefore suppose Δ T ₁(k+j)=0, j>=1, thus formula (5) is reduced to formula (6):

${\tilde{T}}_P\left(k\right)=G\&CenterDot;\mathrm{\&Delta;U}\left(k\right)+z\left(k\right)+\stackrel{\&OverBar;}{H}\&CenterDot;\mathrm{\&Delta;}{T}_1\left(k\right)---\left(6\right)$

In formula, $\stackrel{\&OverBar;}{H}={\left[\begin{array}{cccc}{h}_{\mathrm{1,0}}& h_{\mathrm{2,1}}& ,...,& h_{N,N-1}\end{array}\right]}^T.$

Getting performance index function is:

$J\left(k\right)={(w_P\left(k\right)-{\tilde{T}}_P\left(k\right))}^{T}Q(w_P\left(k\right)-{\tilde{T}}_P\left(k\right))+\mathrm{\&Delta;U}{\left(k\right)}^T\mathrm{R\&Delta;U}\left(k\right)---\left(7\right)$

In formula, w _p(k)=[w (k+1) ... w (k+N)] ^tfor the reference target value vector of following overheating steam temperature;

Q＝diag(q ₁,…,q _N), $R=\mathrm{diag}(r_1,...,r_{N_u}).$

In forecast model formula (6) substitution formula (7), and ask extreme value to obtain secondary GPC controller increment Delta u (k):

$\mathrm{\&Delta;u}\left(k\right)=\mathrm{\&Delta;u}\left(k\right|k)=d^T(w_p\left(k\right)-z\left(k\right)-\stackrel{\&OverBar;}{H}\mathrm{\&Delta;}{T}_1\left(k\right))---\left(8\right)$

In formula, $d^T={\left[\begin{array}{cccc}1& 0& ...& 0\end{array}\right]}_{1\&times;N_u}{(G^T\mathrm{QG}+R)}^{-1}{G}^{T}Q.$

Coordinate control algolithm according to two-stage, use O ₂(k) the Δ T in replacement formula (8) ₁(k) signal, final that secondary GPC controller is exported u (k):

$u\left(k\right)=u(k-1)+\mathrm{\&Delta;u}\left(k\right)=u(k-1)+d^T(w_p\left(k\right)-z\left(k\right)-\stackrel{\&OverBar;}{H}{O}_2\left(k\right))---\left(9\right)$

4. utilize formula (10) to calculate secondary desuperheating water valve controlled quentity controlled variable u ₂(k) also output,

u ₂(k)＝K ₂(u(k)-T _2d(k)) (10)

In formula, T _2d(k) be the measured temperature of secondary attemperator outlet.

5. for revised First stage steam setting value T ' _sp1(k), first order calculation GPC controller output.After utilizing two-stage coordination signal to revise First stage steam setting value, after this computational process and secondary GPC controller all fours, unique difference is, due to the input that do not feedover, therefore only need make the output signal O of two-stage coordination control algolithm in formula (9) ₂(k)=0.

6. all fours formula (10) first order calculation desuperheating water valve controlled quentity controlled variable u ₁(k) also output.

Embodiment:

(1), before algorithm is implemented, obtain the transfer function model of I and II steam temperature related object by step response test.Because the design process of I and II is basic identical, therefore emphasis describes as an example of secondary example below.

If by step response test, and utilize two-point method to obtain the transfer function W of First stage steam to one-level desuperheating water valve opening ₁(s)=-1.12/ (1+20s) ⁵(DEG C/%); The transfer function W of overheating steam temperature to one-level desuperheating water valve opening ₃(s)=-1.43/ (1+20s) ¹⁰(DEG C/%); The transfer function W of secondary leading steam temperature to secondary desuperheating water valve opening ₂₁(s)=-0.21/ (1+15s) ²(DEG C/%); The transfer function W of overheating steam temperature to secondary desuperheating water valve opening ₂(s)=-0.27/ (1+21s) ⁵(DEG C/%).

(2) according to W ₃(s)=W _d(s) W ₁(s), utilize " Series Expansion Method " to try to achieve the transfer function W of overheating steam temperature to First stage steam _d(s)=1.28/ (1+20s) ⁵(DEG C/DEG C); In like manner try to achieve the transfer function W of overheating steam temperature to secondary leading steam temperature ₂₂(s)=1.28/ (1+25s) ³(DEG C/DEG C).

(3), in each control cycle, the two-stage of utilizing two-stage to coordinate control algolithm calculating current time is coordinated signal O ₁and O (k) ₂(k).

(4) utilize formula (1) to First stage steam setting value T _sp1(k) revise, and O ₂(k) be incorporated into secondary GPC controller as feed-forward signal.

(5) utilize two-stage to coordinate the control output u of signal and Generalized Prediction-ratio (GPC-P) tandem control algolithm difference first order calculation and secondary desuperheating water valve ₁and u (k) ₂(k).Taking secondary as example:

1. for W ₂₁(s), utilize the attenuation curve method secondary proportional controller parameter K of adjusting of adjusting ₂=-10, and ask the transfer function W of homophony control channel equivalence controlled device ₀₂(s)=(K ₂w ₂₁(s) W ₂₂(s))/(1+K ₂w ₂₁(s))=2.7/ ((1+25s) ³(225s ²+ 30s+3.1)).

2. GPC controller relevant parameter is set, makes sampling time T _s=10 seconds, prediction step number N=25, controlled step number N _u=2, output error weight matrix Q=I ₆₀, control matrix R=I ₂.

3. by W ₀and W (s) _d(s) after discretization, obtain shape suc as formula (2), with the overheating steam temperature CARIMA model of disturbance term, wherein:

A(q ^-1)＝1-5.627q ^-1+14.33q ^-2-21.84q ^-3+22.15q ^-4-15.7q ^-5+7.903q ^-6-

；

2.801q ^-7+0.6694q ^-8-0.09732q ^-9+0.006517q ^-10

B(q ^-1)＝0.0004124+0.005531q ^-1-0.007992q ^-2-0.006617q ^-3+0.01714q ^-4-

；

0.009722q ^-5+0.0007602q ^-6+0.0008774q ^-7-0.0001857q ^-8-6.236×10 ^-6q ^-9

D(q ^-1)＝0.0002203q ^-1+0.003225q ^-2-0.002872q ^-3-0.004647q ^-4+0.007465q ^-5-

0.003814q ^-6+0.0005264q ^-7+0.0003033q ^-8-0.0001088q ^-9-3.303×10 ^-6q ^-10

4. use formula (4) recursion to calculate E _j(q ^-1) and F _j(q ^-1);

5. utilize formula (9) to calculate the output of secondary GPC controller, wherein,

$\stackrel{\&OverBar;}{H}={[\mathrm{0,0.0002,0.0047,0.0238,0.0674},...,\mathrm{1.2607,1.2662,1.2703}]}_{1\&times;25}^T;$

$\begin{array}{c}{d}^T{\left[\begin{array}{cccc}1& 0& ...& 0\end{array}\right]}_{1\&times;N_u}{(G^T\mathrm{QG}+R)}^{-1}{G}^{T}Q=\\ {[\mathrm{0,0.0002,0.0039,0.0153,0.031,0.0449},...,\mathrm{0.028,0.0276,0.0273,0.0271}]}_{1\&times;25}\end{array}.$

6. utilize formula (10) to calculate secondary desuperheating water valve controlled quentity controlled variable u ₂(k) also output;

7. similar secondary, for revised First stage steam setting value T ' _sp1(k), first first order calculation GPC controller output, and then first order calculation desuperheating water valve controlled quentity controlled variable u ₁(k) also output.

Claims (3)

1. a fired power generating unit overheating steam temperature two-stage predictive coordinated control method, is characterized in that, comprises the steps:

(1), under steady state condition, firsts and seconds desuperheat spray water control system is switched to manual mode, and carries out respectively desuperheating water valve step response test;

(2) utilize two-point method to obtain respectively the transfer function of following object: the transfer function W of one-level leading steam temperature to one-level desuperheating water valve opening ₁₁(s) (DEG C/%); The transfer function W of First stage steam to one-level desuperheating water valve opening ₁(s) (DEG C/%); The transfer function W of overheating steam temperature to one-level desuperheating water valve opening ₃(s) (DEG C/%); The transfer function W of secondary leading steam temperature to secondary desuperheating water valve opening ₂₁(s) (DEG C/%); And the transfer function W of overheating steam temperature to secondary desuperheating water valve opening ₂(s) (DEG C/%);

(3) utilize Series Expansion Method to ask the transfer function W of overheating steam temperature to First stage steam _d(s) (DEG C/DEG C), the transfer function W of First stage steam to one-level leading steam temperature ₁₂(s) (DEG C/DEG C), and the transfer function W of overheating steam temperature to secondary leading steam temperature ₂₂(s) (DEG C/DEG C);

(4), in each control cycle, the one-level of utilizing two-stage to coordinate control algolithm calculating current time is coordinated signal O ₁(k) and secondary coordinate signal O ₂(k);

(5) utilize one-level to coordinate signal O ₁(k), by formula (1), First stage steam is set value to T _sp1(k) revise, correction result is T ' _sp1(k):

T′ _sp1(k)＝T _sp1(k)+O ₁(k) (1)

And secondary is coordinated to signal O ₂(k) be incorporated into secondary GPC controller as feed-forward signal;

(6) utilize one-level to coordinate signal O ₁(k) and series connection one-level GPC controller and the controlled quentity controlled variable u of one-level proportional controller first order calculation desuperheating water valve ₁(k) also output, utilizes secondary to coordinate signal O ₂(k) and the secondary GPC controller of series connection and secondary proportional controller calculate the controlled quentity controlled variable u of secondary desuperheating water valve ₂(k) also output.

2. a kind of fired power generating unit overheating steam temperature two-stage predictive coordinated control method according to claim 1, is characterized in that: in described step (4):

If Z ₂(k)=0 and T ₂(k) <T _sp2and Z (k) ₁(k) >0, or, Z ₂(k)=100 and T ₂(k) >T _sp2and Z (k) ₁(k) <100, O ₁(k)=α e ₂and O (k) ₂(k)=0, otherwise O ₁(k)=0 and O ₂(k)=Δ T ₁(k),

Wherein, Z ₁and Z (k) ₂(k) be respectively firsts and seconds desuperheating water valve position feedback signal; T ₂(k) be overheating steam temperature measuring-signal; T _sp2(k) be overheating steam temperature setting value; O ₁(k) coordinate the output signal of control algolithm to one-level attemperation control for two-stage, it is added on the duty setting signal of First stage steam; O ₂(k) coordinate the output signal of control algolithm to secondary attemperation control for two-stage, it is as an input signal of secondary GPC controller; e ₂(k)=T _sp2(k)-T ₂(k) be secondary super-heated steam temperature control deviation; α is two-stage cooperation index, conventionally gets α=0.8; Δ T ₁(k) be the variable quantity of First stage steam.

3. a kind of fired power generating unit overheating steam temperature two-stage predictive coordinated control method according to claim 1, is characterized in that: described step (6) comprises the steps:

1. for W ₁₁and W (s) ₂₁(s), utilize the attenuation curve method firsts and seconds proportional controller parameter K of adjusting respectively ₁and K ₂, wherein K ₁and K ₂all be less than 0, and ask respectively the transfer function W of firsts and seconds GPC controller equivalence controlled device ₀₁and W (s) ₀₂(s), wherein, W ₀₁(s)=(K ₁w ₁₁(s) W ₁₂(s))/(1+K ₁w ₁₁(s)), W ₀₂(s)=(K ₂w ₂₁(s) W ₂₂(s))/(1+K ₂w ₂₁(s));

2. firsts and seconds GPC controller relevant parameter is set, comprises sampling time T _s, prediction step number N, controls step number N _u, output error weight matrix Q, and control matrix R;

3. for overheating steam temperature setting value T _sp2(k) calculate the output of secondary GPC controller;

4. calculate the controlled quentity controlled variable u of secondary desuperheating water valve ₂(k) also output;

5. for revised First stage steam setting value T ' _sp1(k) first order calculation GPC controller output;

6. the controlled quentity controlled variable u of first order calculation desuperheating water valve ₁(k) also output.