JPS58136903A - Optimum control system of heat power plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a thermal power plant control system.

Especially the plants! The present invention relates to a thermal power plant control system suitable for use in cases where the temperature varies greatly over time.

The conventional optimal control system for thermal power plants is 1. As shown in Fig. ig1, it consists of a model-embedded optimal control system 100, a master controller 200 of a thermal power plant control system, and a subloop controller 300, and receives load commands Lc from a central power dispatch center (hereinafter referred to as "intermediate dispatch").
(=Thermal power generation plan following ELD Junin F'C) 4
00t-control.

That is, the mask controller 200#i of the thermal power plant control system, load command Lc (=EL
D+AFC)'f: Load demand L subjected to change rate restriction processing
o Based on the water supply light demand Fvwos fuel flow demand FPD, air flow demand FAD, spray flow demand FIPD and recirculation gas flow demand Fa
vor is determined in advance (feed-forward system #), and the demand for each of the above-mentioned manipulated variables is corrected by feedback control of main steam pressure Pwms, main steam temperature ['rrs, gas Ot, and writing steam temperature TIH, Corrected demand F'FWD%F'to, P"an, ?'PD and P'a凰Dt- are created. Note that the turbine steam flow rate demand F舅10 is determined by feedback control of 1 generator output MW. do.

Mata, mask controller 200Fi, rate of change of load demand Lo Lax and furnace ice wall outlet steam temperature Tww
The optimal control system 100 with a built-in model consists of the mask controller 200° subloop controller 300 of the thermal power generation plan) control system, and the thermal power generation plan) 40 (1
The combined system is to be controlled, and the load 7' cloak change force Ltsmt disturbance from the mask controller 200 is used, as well as the main steam temperature deviation TM, the furnace water wall output O steam temperature change TWWI, and the reheat steam temperature deviation Tmmm. As a control variable, the disturbance generation process is regarded as a white noise generation process, and the characteristics of the control object are identified using an autoregressive moving average (ARM model) model, and optimal control is performed using a quadratic evaluation function. The output variable of the model is the load demand change rate L! from the mask controller 200. 1m s
Main steam temperature deviation T w s m s Furnace water wall outlet steam temperature change wheel Twv* and reheat steam temperature deviation Tmam. In addition, the input variable is the fuel flow rate demand correction signal ΔF
FD, spray flow rate demand correction signal ΔFIFD, and recirculation gas flow rate demand correction signal ΔPa.

Thermal power plant control system's pull loop Φ controller 300H, 11) Corrected demand F% for each manipulated variable shown in 2
sne ]”rye * F~D, F'AD, F
"lPD and water flow rate F rw , fuel flow rate FF, air flow rate Fm, spray flow rate Pa P and recirculation gas flow rate Fo
control u.

F“omn=F”amp+ΔFaun
) Here, f(ΔFFD) is the air flow rate demand correction signal corresponding to the fuel flow rate demand correction signal.By the way, as described above, in the conventional thermal power plant optimum control system, the master controller 200. ? A nine-system combination of the proof controller 300 and the thermal power plant 400 was controlled, and the characteristic tARMA of the controlled object was identified. The output variables of the model are mask controller 200
- Rih et al. (D Load demand change rate Lols Main steam temperature deviation Twmxs Furnace ice wall outlet steam temperature change rate Tww+a and precious heat steam temperature difference T 11111, and the input variables are fuel flow rate correction signal jFyo, The spray flow rate demand correction signal ΔF IPD and the recirculating gas flow rate demand correction signal ΔFans.Thermal power plants burn fuel to change the gas temperature, and the energy of the combustion gas is transferred to steam through the metal of the evaporator tube. 9. A: The response delay for steam temperature changes due to changes in fuel flow rate is large.
Conventional thermal power plant optimal control systems that use fuel flow rate and steam temperature as input and output variables of the 'f'LMA model cannot adapt to changes in physical properties due to fluctuations (disturbances) in fuel properties, air properties, etc. There was a problem that control characteristics deteriorated.

An object of the present invention is to provide an optimal control system for a thermal power plant that can quickly adapt to changes in the characteristics of a thermal power plant due to changes (disturbances) in the properties of fuel, air, etc., and perform good load follow-up control. .

In thermal power plants, fuel is combusted to change the gas temperature, and the energy of the combustion gas is transferred to steam through the metal of the evaporator tube. This process can be expressed by a linear equation.

(a) Gas system process where, rl: Specific weight of combustion gas v9: Gas side volume FF: Fuel flow rate Fm: Air flow rate F5゜: Combustion gas flow rate H,: Combustion gas enthalpy Hr: Calorific value Hm: Air enthalpy Qo: amount of heat transferred from combustion gas to evaporator tube metal C1,! Heat transfer coefficient from combustion gas to evaporator tube metal A1: Contact area between combustion gas and evaporator tube metal T1: Combustion gas temperature T, : Evaporator tube metal temperature C, : Combustion gas specific heat (b) Evaporator tube process where * Qss! Amount of heat transfer from evaporation metal to steam C1: Evaporation tube metal specific heat Mat Evaporation tube metal weight (C) Steam system process where, r: Steam specific weight ■: Steam side volume F, 1: Inlet steam flow rate Fl , : Outlet steam flow rate H, : Steam enthalpy Hl : Inlet steam enthalpy T, : Steam temperature C1, : Heat transfer coefficient from evaporator tube metal to steam A □ : Contact area between evaporator tube metal and steam +21. (31, (From Equation 41, it can be seen that the response delay in steam temperature changes due to changes in fuel flow rate becomes large. Therefore, the properties of fuel and air, that is, the calorific value.

There is also a large response delay when the air temperature (enthalpy) fluctuates and the steam temperature changes. For this reason, conventional optimal control systems for thermal power plants that use fuel flow rate and steam temperature FIK as model input/output variables cannot adapt to changes in characteristics due to fluctuations (disturbances) in fuel properties, air properties, etc.

However, +2), (As seen from Equation 31, the response delay for combustion gas temperature and metal temperature changes due to fuel flow rate changes is smaller than that for steam temperature changes.

For this reason, the properties of fuel, properties of air, i.e. calorific value,!
2 The temperature (enthalpy) fluctuates, and the response delay for changes in combustion gas temperature and metal temperature also becomes smaller compared to changes in steam temperature.

In the present invention, changes in plant characteristics due to fluctuations (disturbances) in fuel properties, air properties, i.e., calorific value, and air temperature f (enthalpy) are observed by observing the combustion gas temperature and evaporator tube metal temperature rather than the steam temperature. With this in mind, we added combustion gas temperature and evaporator tube metal temperature as output variables of the model.

An embodiment of the present invention is shown in FIGS. 3 and 4. The present invention provides a model-embedded optimal control system 500, a mask controller 600 for a thermal power plant control system, and a subloop.
The mask controller 600 and the subloop controller 300 of the fire cuffant control system control the thermal power generation plan) 400'i by following the load command Lc from the intermediate supply, and the model built-in optimal control system 500 Master controller 600 of thermal power plant control system. The subloop controller 300 and the thermal power generation plan) 400t' combined system is set as the control target, and the characteristic iARMA model that combines this control target and the load command from the intermediate supply is sequentially identified.
Optimal control is performed using the evaluation function of the following form. This will be explained in detail in the 0th order, which uses combustion gas temperature and evaporator tube metal temperature in addition to steam temperature as model output variables.

Master controller 60 of thermal power plant control system
0Fi, load command Lc (=ELD+A]'C from intermediate supply
) based on the nine load demands LnK and the change force limit processing,
Water supply flow rate demand F ywn, fuel flow rate demand FFD
, air flow rate demand PAD, spray flow rate demand FI
PD and recirculation gas flow rate demand Fagot are determined in advance (feed forward control), and main steam pressure PMms main steam temperature T + gss gas 0. ．． 0. Then, the demand for each of the above manipulated variables is corrected by feed pack control of the reheat steam temperature TRI, and the corrected demand F~v!
I, FGE1eP'AD, F'ste and? -Create turtle Dt. In addition, the turbine steam flow rate demand FII
IIB is determined by feedback control of one generator output MW. Mari, mask controller 5ooFis
Negative W demand L! IO change wheel Let, change in furnace water wall outlet steam temperature Tww * Secondary superheater combustion gas temperature T @! III Rate of change To1111m and 2
Next superheater meta km KT - 0ffi conversion 甐 T 菖 snow 謨 膨 鳳 ・Built-in model optimal control system empty OO fire Kaplant control system O″V ・ Controller 600
The control target is a system that combines the subloop controller 300 and the thermal power generation plan) 400, and the load demand change rate La from the mask controller 600 is
e disturbance and main steam temperature deviation Tm5m*rate of change in steam temperature at furnace water wall outlet Tww+a.

By using the reheat steam temperature deviation Tmmm, the secondary superheater combustion gas temperature change wheel TOIII, the secondary superheater metal temperature change rate T, and the Bmx iris as the control variables, the characteristic t-(which is a combination of the above disturbance and the controlled object) is expressed in equation 51. The person is sequentially identified using the RMA model shown in FIG.

X(k)=A11)X(k-1)-1-Aj21X(
k-2)+-...-+AMX(k-M)+B(flu
(k-1)+B(21u(k-2)-)-・-・・-
+BIMu (k-M)+ξ(k)
(51L!1飄(k-i)=(k-1>
The load demand change rate at the time T 111 (k-2) t (k- is the main steam temperature deviation at the time Tvvm (k l>! (k L) t) Reheat steam temperature deviation T@!-Ten (k-1> at the time of wealth (k-1> s) Secondary superheater combustion gas temperature change rate T@un (k-j )s Secondary superheater metal temperature change rate at time (k-t) jFrD(k-t)! Fuel flow rate demand correction signal at time (k-1) jFsp*(spray flow rate at time 41(k-1) Demand correction signal 4P@ve (k-1's Recirculation gas flow rate demand correction signal at (k -1) point a, order"s*(4-..."as (6ass c
a, 1 (5) can be separated into two equations as follows.

x℃)=”tt(1)Xs(k 1)+a, 1(21x
1(k-2)+----・+a1,9x, (k M)
+ζ*OL) (6)!
'(k)=3:A'(IIK'(k-υ+A'12)K
'(k-2)+-----+AM)Xτ-M)+B
'1l)L/(k-1)+B'121L/(k-2)+
・・・・・・+B'MI(k)+ξ'(k)
(7) (163 Equation (6) has the parameter “tt(6(t=1,2111
1+, M) can be transformed as follows.

xt(k)=C1(k)Am(k)+ξt(')
(8) Here, CI(k)(XI
(k-1)XI(k-2)--XI(k-M))A
1 gradient = [”tt(isk) att(z*k)”’ B
+ Its(Me k)"1all(t, k) The transition equation of "5t (4 parameters AI(g)) at gk is assumed to be linear.

a, (k+i) = At(k)
(9) When a Kalman filter is constructed for equations (8) and (9), the following K is obtained.

Here, the estimated value Pl(
covariance matrix W of the estimation error of (g)):AtoL), the variance of C1(g)), equation (7) t-1, c9 MeI AIc6 (t=
1.2. −, M) can be transformed as follows.

x'(k)=gC trace) AI(')+ξHayabusa)
αυb Hatake 3 (4k) s bI at time k
j(a) Harameter A, the transition equation of (k) is assumed to be linear.

λt(k+1>Tomi A, to) 0
When a Kalman filter is constructed for the zan and as expressions, it becomes as follows.

trace) = (p-! (k-1)+cS(k)w-!C
m(k))-""where, 4(k)-s
A! Covariance matrix Wlzξ'(kX) Covariance matrix Ql-03 Equation K YoD Calculation 7'? :, At(')-
A! (')? :(Substituting into 512 results in the following.

xat＞= fmx(k-1)+i2+x(k-2)
+-・-Jushin JX (k-M)+fRt+u (k-13
+821u(k-2)+...-+BMu tk-M)
+ξ(t)') (
14Here, mA(Z):A(Estimation of A1 Meeting(force!Estimated value of B(6)) To convert the α4 equation into a state transition expression, we write the a$ equation as follows. become.

The α0 expression can be expressed as a state transition expression as shown in the first order.

Z(k) = Φ−Z (k −1)+ P −u (k
−1))−V(k) αDx(k)=(r o
−−−−−−−・o ) Z (k)
Ql cocochi z'(k)=(ze(') Zt(
')...ZL('))V'(k) = [ξ exposure)
0-...0 ]Evaluation function JFi, the following 02-order form evaluation function is used.

J=E(Σ(di(k+1)QZ(k+i)+u'(k
+1-1) Ru(k+-1-1))]s ξ Here, E: Symbol representing expected value Q: (M-4)X(M-4) Next half-ball constant value matrix (weight) R: 3X3 The following positive definite matrix (weight) αη, equation 61 is given by dynamic meeting programming (DP
) t - can be applied to obtain the optimal manipulated variable - f) using the following recurrence formula.

That is, the model built-in optimal control system 500 is as follows.

Load demand change car Log from mass controller 600, main steam temperature deviation Tw, furnace water wall outlet steam temperature change rate Twwm, reheating steam temperature deviation Tmwms, secondary superheater combustion gas temperature change rate Tolsmm, and secondary heating unit metal Using the temperature change vehicle TMIIF IIt, the fuel flow rate demand correction signal IFrn is generated by @formula.

Determine the optimal I[ of the spray flow rate demand correction signal I Fspo and the recirculation gas flow rate demand correction signal ΔFoam.

The subloop controller 30G of the thermal power plant control system uses the correction demand F~re for each manipulated variable shown in the @formula.
, P'FWII%! I, P'AD, F"IPD
and P'o**, the turbine steam flow rate FMS
, water supply flow rate Pyv, fuel flow rate F, air flow rate FhS, spray flow rate Fap, and recirculation gas flow rate rank.

Here, of(jFyn) is the air flow rate demand correction signal corresponding to the fuel flow rate demand correction signal.As can be seen from the above description, according to one embodiment of the present invention, the master controller of the thermal power plant control system, ? Proop controller and thermal power generation plan) 1
Using the combined system as a control object, the characteristics of this control object are sequentially identified using a model.

In the thermal power plant optimal control system that optimally controls the controlled object based on this identification result, in addition to the steam temperature, combustion gas temperature and evaporator pipe metal temperature are used as output variables of the model, so fuel properties and air properties are In other words, it is possible to quickly adapt to fluctuations in plant characteristics due to fluctuations (disturbances) in calorific value and air temperature (enthalpy), and perform good load follow-up control.

In the embodiment of the invention, the secondary superheater combustion gas temperature and the secondary superheater metal temperature Il were used as the combustion gas temperature and the evaporator tube metal temperature, respectively, but the thermal power plant uses one economizer, one furnace ice wall, Primary superheater, secondary superheater,
It may consist of heat exchangers such as a primary reheater and a secondary reheater, and the combustion gas temperature and metal temperature of these heat exchangers may be used.

Previously, in the embodiment, the same combustion gas temperature and metal temperature of the heat exchanger were used, such as the secondary superheater combustion gas temperature and the secondary superheater metal temperature, but the combustion gas temperature of a different heat exchanger Temperature and metal SW may be used in combination. For example, a combination of the economizer combustion gas temperature and the secondary superheater metal temperature is used. Or 1
The economizer combustion gas temperature and the primary superheater metal temperature may be used in combination.

In the embodiment of the invention, combustion gas temperature and metal temperature are used, but only combustion gas temperature or
It is also possible to use only the metal temperature.

According to the present invention, the master controller of the thermal power plant control system
In a thermal power plant optimal control system that uses a system that combines a controller, a subloop controller, and a thermal power plant as a control object, sequentially identifies the characteristics of this control object as a model, and optimally controls the control object based on the identification results.

In addition to the steam temperature, the combustion gas temperature and evaporator tube metal temperature are used as output variables of the model, so the plan is based on the properties of the fuel, the properties of the air, i.e. the calorific value, and the fluctuation (disturbance) K of the air temperature (enthalpy)! It is possible to perform good load following control by quickly adapting to fluctuations in performance.

[Brief explanation of the drawing]

Claims (1)

[Claims] 1. In the thermal power plant control system, at least one of the boiler gas temperature and boiler tube metal temperature and the amount of fuel tpIa are observed to determine the fuel property change t4, and the fuel flow rate is determined based on the estimated data. tv4 adjustment
- Features an optimal control system for thermal power plants.