CN103134046A - 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 that needs in unit running process key monitoring.

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

Present 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 the 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: for the problem and shortage of above-mentioned prior art existence, the purpose 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 is regulated, 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 state, and carry 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) (℃/%); The transfer function W of First stage steam to one-level desuperheating water valve opening ₁(s) (℃/%); The transfer function W of overheating steam temperature to one-level desuperheating water valve opening ₃(s) (℃/%); The transfer function W of secondary leading steam temperature to secondary desuperheating water valve opening ₂₁(s) (℃/%); And overheating steam temperature is to the transfer function W of secondary desuperheating water valve opening ₂(s) (℃/%);

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

(4) in each control cycle, utilize two-stage to coordinate the one-level coordination signal O that control algolithm is calculated current time 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 T _sp1(K) revise, correction result is T _s' _p1 (k):

T _s' _p1(k)=T _sp1(k)+O ₁(K) _ 1) and secondary coordinate 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 the 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 _sp2(k) and Z ₁(k)〉0) or (Z ₂(k)=100 and T ₂(k)〉T _sp2(k) and Z ₁(k)＜100), (O ₁(k)=α .e ₂(k) and O ₂(k)=0), otherwise (O ₁(k)=0 and O ₂(k)=Δ T ₁(k)),

Wherein, Z ₁(k) and Z ₂(k) be respectively firsts and seconds desuperheating water valve position feedback signal; T ₂(k) be the overheating steam temperature measuring-signal; T _sp2(k) be the overheating steam temperature setting value; O ₁(k) be that two-stage coordinates control algolithm to the output signal of one-level attemperation control, it is added on the duty setting signal of First stage steam (seeing accompanying drawing 1); O ₂(k) coordinate control algolithm to the output signal of secondary attemperation control for two-stage, it is as an input signal (seeing accompanying drawing 1) of secondary GPC controller; e ₂(k)=T _sp2(k)-T ₂(k) be secondary super-heated steam temperature control deviation; α is the two-stage cooperation index, usually 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 ₁₁(s) and W ₂₁(s), utilize the attenuation curve method firsts and seconds proportional controller parameter K of adjusting respectively ₁And K ₂, K wherein ₁And K ₂All less than 0, and ask respectively the transfer function W of firsts and seconds GPC controller equivalence controlled device ₀₁(s) and W ₀₂(s), wherein, W ₀₁(s)=(K ₁.W ₁₁(s) .W ₁₂(s))/(1+K ₁.W ₁₁(s)), W ₀₂(s)=(K ₂.W ₂₁(s) .W ₂₂(s))/(1+K ₂.W ₁₁(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 _s' _p1(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: regulate surplus in the situation that secondary desuperheating water valve exists, 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 in the situation that secondary desuperheating water valve is in the up/down limit, this algorithm can take full advantage of the adjusting surplus of one-level water spray, assists the secondary water spray to control overheating steam temperature.The method can effectively improve the control accuracy of overheating steam temperature, further reduces control deviation.

Description of drawings

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

The specific embodiment

Below in conjunction with the drawings and specific embodiments, further illustrate the present invention, should understand these embodiment only is used for explanation the present invention and is not used in and limits the scope of the invention, after having read the present invention, those skilled in the art all fall within the application's claims limited range to the modification 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 the design two-stage, and adopt GPC-P (Generalized Prediction-ratio) cascade control strategy to realize respectively the control that the firsts and seconds desuperheat is sprayed water, make the co-ordination of two-stage water spray, that effectively processes simultaneously the steam temperature object delays greatly characteristic, 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 state, and carry 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) (℃/%); The transfer function W of First stage steam to one-level desuperheating water valve opening ₁(s) (℃/%); The transfer function W of overheating steam temperature to one-level desuperheating water valve opening ₃(s) (℃/%); The transfer function W of secondary leading steam temperature to secondary desuperheating water valve opening ₂₁(s) (℃/%); The transfer function W of overheating steam temperature to secondary desuperheating water valve opening ₂(s) (℃/%).

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

(4) in each control cycle, utilize two-stage to coordinate the two-stage coordination signal O that control algolithm is calculated current time ₁(k) (one-level coordination signal) and O ₂(k) (secondary coordination signal), see accompanying drawing 1.In figure, f ₁(x) and f ₂(x) be the function of load, be used 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, namely in the situation that existing, secondary desuperheating water valve regulates surplus, the adjusting task of Ying Youqi complete independently to overheating steam temperature, simultaneously for eliminating the First stage steam variation to the impact of overheating steam temperature, should by design two-stage decoupling zero loop, make the two-stage desuperheating water control and realize Approximate Decoupling; Be in the up/down limit 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 of regulating surplus simultaneously, should cancel two-stage decoupling zero loop, after simultaneously the super-heated steam temperature control deviation being multiply by certain coefficient, on the setting value of First stage steam of being added to, thereby make one-level desuperheat water spray participate in adjusting to overheating steam temperature directly, utilize it to regulate surplus and further reduce the 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 _sp2(k) and Z ₁(K)〉0) or (Z ₂(k)=100 and T ₂(k)〉T _sp2(k) and Z ₁(k)＜100),

(O so ₁(k)=α .e ₂(k) and O ₂(k)=0),

Otherwise

(O ₁(k)=0 and O ₂(k)=Δ T ₁(k))

Wherein, Z ₁(k) and Z ₂(k) be firsts and seconds desuperheating water valve position feedback signal; T ₂(k) be the overheating steam temperature measuring-signal; T _sp2(k) be the overheating steam temperature setting value; O ₁(k) be that two-stage coordinates control algolithm to the output signal (being that one-level is coordinated signal) of one-level attemperation control, it is added on the duty setting signal of First stage steam (seeing accompanying drawing 1); O ₂(k) coordinate control algolithm to the output signal (being that secondary is coordinated signal) of secondary attemperation control for two-stage, it is as an input signal (seeing accompanying drawing 1) of secondary attemperation control device; e ₂(k)=T _sp2(k)-T ₂(k) be secondary super-heated steam temperature control deviation; α is the two-stage cooperation index, usually 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 T _sp1(k) revise, and O ₂(k) be incorporated into secondary GPC controller (seeing accompanying drawing 1) as feed-forward signal.

T _s' _p1(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 ₁(k) and u ₂(k).

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

1. for W ₂₁(s), utilize the attenuation curve method secondary proportional controller parameter K of transferring of adjusting ₂(negative value), and ask the transfer function W of homophony control channel equivalence controlled device ₀₂(s)=(K ₂.W ₂₁(s) .w ₂₂(s))/(1+K ₂.W 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 ₉₅Be 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 _NAnd r ₁...,

Be corresponding weight coefficient.

3. calculate the output of secondary GPC controller.

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

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

In formula: u (k-1) is the subloop setting value of k-1 secondary homophony GPC controller output constantly; ξ (k) is random disturbances; q ^-1Be backward shift operator, move one after subscript-1 expression, move the i position after-i represents; Δ=1-q ^-1

$A\left(q^{-1}\right)=1+\underset{i=1}{\overset{n_a}{\mathrm{\Σ}}}{a}_i{q}^{-i};$ $B\left(q^{-1}\right)=\underset{i=0}{\overset{n_b}{\mathrm{\Σ}}}{b}_i{q}^{-i};$ $D\left(q^{-1}\right)=\underset{i=1}{\overset{n_d}{\mathrm{\Σ}}}{d}_i{q}^{-i};$ 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.Attention is compared with conventional GPC algorithm, and formula has increased last in (2), i.e. the disturbance term of First stage steam.

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

$H_j\left(q^{-1}\right)=E_j\left(q^{-1}\right)D\left(q^{-1}\right)=\underset{i=0}{\overset{n_d+j-1}{\mathrm{\Σ}}}{h}_{j,i}{q}^{-i};$ $E_j\left(q^{-1}\right)=\underset{i=0}{\overset{j-1}{\mathrm{\Σ}}}{e}_{j,i}{q}^{-i};$ $F_j\left(q^{-1}\right)=\underset{i=0}{\overset{n_a}{\mathrm{\Σ}}}{f}_{j,i}{q}^{-i},$ G wherein _{J, i}, h _{J, i}, e _{J, i}And f _j,iIt is respectively the coefficient of predicting forward j the i time item of corresponding polynomial during the 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 with vector form:

${\tilde{T}}_P\left(k\right)=G.\mathrm{\ΔU}\left(k\right)+z\left(k\right)+H.{\mathrm{\Δ}\tilde{T}}_1\left(k\right)---\left(5\right)$

In formula, ${\tilde{T}}_P\left(k\right)={\left[\begin{array}{ccc}{T}_2(k+1|k)& ,...,& T_2(k+N|k)\end{array}\right]}^T;$

ΔU(k)＝[Δu(k|k),…,Δu(k+N _u-1|k)] ^T；

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

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,j1-,…,-g _j,0].Δu(k|k)+F _j(q ^-1).T ₂(k),j＝1,2,…,N。

The variable quantity of First stage steam will be unknown due to the moment in future, therefore suppose Δ T ₁(k+j)=0, j 〉=1, thus formula (5) is reduced to formula (6):

${\tilde{T}}_P\left(k\right)=G.\mathrm{\ΔU}\left(k\right)+z\left(k\right)+\stackrel{\_}{H}.{\mathrm{\ΔT}}_1\left(k\right)---\left(6\right)$

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

Getting performance index function is:

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

In formula, w _P(k)=[w (k+1) ... w (k+N)] ^TReference target value vector for 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 get secondary GPC controller increment Delta u (k):

$\mathrm{\Δu}\left(k\right)=\mathrm{\Δu}\left(k\right|k)=d^T(w_P\left(k\right)-z\left(k\right)-\stackrel{\_}{H}\mathrm{\Δ}{T}_1\left(k\right))---\left(8\right)$

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

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):

$u\left(k\right)=u(k-1)+\mathrm{\Δu}\left(k\right)=u(k-1)+d^T(w_P\left(k\right)-z\left(k\right)-\stackrel{\_}{H}{O}_2\left(k\right))---\left(9\right)$

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)) in (10) formula, T _2d(k) be the measured temperature of secondary attemperator outlet.

5. for revised First stage steam setting value T _s' _p1(k), first order calculation GPC controller output.After utilizing two-stage coordination signal that the First stage steam setting value is revised, after this computational process and secondary GPC controller all fours, unique difference is due to not feedforward input, therefore only need make the middle two-stage of formula (9) coordinate the output signal O of control algolithm ₂(k)=0 gets final product.

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 following emphasis describes as an example of secondary example.

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

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

(3) in each control cycle, utilize two-stage to coordinate the two-stage coordination signal O that control algolithm is calculated current time ₁(k) and O 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 ₁(k) and u ₂(k).Take secondary as example:

1. for W ₂₁(s), utilize the attenuation curve method secondary proportional controller parameter K of transferring of adjusting ₂=-10, and ask the transfer function W of homophony control channel equivalence controlled device ₀₂(s)=(K ₂.W ₂₁(s) .W ₂₂(s))/(1+K ₂.W 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 ₀(s) and W _d(s) get shape suc as formula (2), with the overheating steam temperature CARIMA model of disturbance term, wherein after discretization:

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,

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

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

7. similar secondary, set value T for revised First stage steam _s' _p1(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 state, and carry 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) (℃/%); The transfer function W of First stage steam to one-level desuperheating water valve opening ₁(s) (℃/%); The transfer function W of overheating steam temperature to one-level desuperheating water valve opening ₃(s) (℃/%); The transfer function W of secondary leading steam temperature to secondary desuperheating water valve opening ₂₁(s) (℃/%); And overheating steam temperature is to the transfer function W of secondary desuperheating water valve opening ₂(s) (℃/%);

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

(4) in each control cycle, utilize two-stage to coordinate the one-level coordination signal O that control algolithm is calculated current time 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 T _sp1(k) revise, correction result is T _s' _p1(k):

T _s' _p1(k)=T _sp1(k)+O ₁(k) (1) and secondary is coordinated 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 the 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 _sp2(k) and Z ₁(k)〉0) or (Z ₂(k)=100 and T ₂(k)〉T _sp2(k) and Z ₁(k)＜100), (O ₁(k)=α .e ₂(k) and O ₂(k)=0), otherwise (O ₁(k)=0 and O ₂(k)=Δ T ₁(k)),

Wherein, Z ₁(k) and Z ₂(k) be respectively firsts and seconds desuperheating water valve position feedback signal; T ₂(k) be the overheating steam temperature measuring-signal; T _sp2(k) be the overheating steam temperature setting value; O ₁(k) be that two-stage coordinates control algolithm to the output signal of one-level attemperation control, it is added on the duty setting signal of First stage steam (seeing accompanying drawing 1); O ₂(k) coordinate control algolithm to the output signal of secondary attemperation control for two-stage, it is as an input signal (seeing accompanying drawing 1) of secondary GPC controller; e ₂(k)=T _sp2(k)-T ₂(k) be secondary super-heated steam temperature control deviation; α is the two-stage cooperation index, usually 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, it is characterized in that: described step (6) comprises the steps:

1. for W ₁₁(s) and W ₂₁(s), utilize the attenuation curve method firsts and seconds proportional controller parameter K of adjusting respectively ₁And K ₂, K wherein ₁And K ₂All less than 0, and ask respectively the transfer function W of firsts and seconds GPC controller equivalence controlled device ₀₁(s) and W ₀₂(s), wherein, W ₀₁(s)=(K ₁.W ₁₁(s) .W ₁₂(s))/(1+K ₁.W ₁₁(s)), W ₀₂(s)=(K ₂.W ₂₁(s) .W ₂₂(s))/(1+K ₂.W 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 _s' _p1(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.

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