JPS6047802A - Turbine monitor control system for estimating rotor stress - Google Patents

Abstract

PURPOSE:To operate a turbine according to a program, by obtaining and displaying a successive retaining time from a stress estimation obtained by means for preditcing a stress occuring in a turbine rotor, when the operating state of turbine is retained. CONSTITUTION:A turbine monitor control system 100 for thermal stress is utilized to monitor a thermal stress occuring on the surface of rotor and a bore 3 in the vicinity of labyrinth packing portions 1, 2 provided rearwardly of first stages in high and medium pressure turbines 200, 300 receiving the greatest amount of heat. The system 100 is further utilized to preset a governor 10 at an optimum speed raising ratio 4 and an automatic load regulator 7 at an optimum load varying ratio, so that a thermal stress may be made lower than a limit value. When a thermal stress including predicted value exceeds an allowable limit to shift into a speed or load controlling mode, a time needed to bring the thermal stress lower than the allowable limit, that is, a successive retaining time is obtained and outputted to a time displaying means 14.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a control system for a steam tanibin, and in particular, suppresses stress in the rotor that occurs due to speed increase and load change to below a permissible value, and enables safe and rapid startup. and a control system that enables rapid load changes.

[Background of the invention]

When starting a steam turbine and changing load, it is necessary to suppress fatigue, that is, life consumption, due to thermal stress generated in the thick portion of the turbine to within an allowable value.

For this reason, especially during speed increase and load change, operation is performed using a speed increase rate and a load change rate based on rotor stress or predicted stress. If the rotor stress generated at this time or the predicted stress is completely reduced to the allowable value, the speed increase rate and load change rate are set to zero to maintain the speed and load.

However, when the speed and load are held, it is difficult to make an operation plan because it is difficult to know how long the speed and load will continue to be held.

[Purpose of the invention]

An object of the present invention is to provide a method for specifying the time when stress or predicted stress becomes less than a permissible value when shifting to holding operation to carry out planned operation.

[Summary of the invention]

In order to achieve the above object, the present invention calculates the predicted value of stress until it becomes below the allowable value, and if the current value of stress exceeds the allowable value, the predicted stress becomes below the allowable value from this point onwards. If the predicted stress value exceeds the allowable value and is maintained even if the current value is below the allowable value, calculate the time during which the predicted stress value exceeds the allowable value, and then operate for 7 hours. It is characterized by informing employees.

[Embodiments of the invention]

FIG. 1 shows the relationship of input and output signals between a thermal stress prediction turbine monitoring and control system 100 and related control systems and plants when a digital computer is used as a disaster example of the present invention. This figure shows the first post-stage labyrinth hacking part 1 of the high-pressure turbine 200 and the first post-stage labyrinth hacking part 2 of the intermediate-pressure turbine 300. This is the one place where the heat exchange between the steam and the metal is most intense because high-temperature, high-pressure steam leaks at high speed through both turbines. Due to this heat exchange, a temperature distribution occurs in the radial direction of the rotor in this vicinity, and a large thermal stress is generated in the rotor surface and bore (center hole) 3. The basic function of the control system 100 of the present invention is to ensure that the thermal stress generated at startup or load change is below a limit value, and the optimum acceleration rate 4 allowed under that condition.
to the governor 10, or the optimum load change rate 6 to A L
R(Automatic: 1 oad l(egula
tor) 7 as a setting value. AL
For example, the first stage post-pressure signal PH1 is fed back to R as a signal representative of the output. An instantaneous target load 9 is applied to the governor 10 from the ALR 7. A speed signal N is fed back to the governor 10. This governor ultimately gives a valve position command 13 to the actuator 12 for controlling the position of the regulating valve 41.

The control monitoring system 100 of the present invention calculates the time (predicted value) 15 required for the thermal stress to fall below the allowable value when the thermal stress (including the predicted value) exceeds the allowable value and shifts to speed or load holding control. It is given to the explicit function 14.

FIG. 2 shows a processing procedure in the thermal stress prediction turbine monitoring and control system 100 of the present invention.

First, the initial temperature distribution determination function (hereinafter referred to as
For simplicity, the display of functions is omitted. The same applies to other calculation prediction and decision functions. ) 101, the initial temperature distribution of the rotor is estimated. Here, the temperature distribution is estimated from the actual measured values of the metal temperature of the inner and outer walls of the first post-death casing in a high-pressure turbine and the steam chamber in an intermediate-pressure turbine, where the rotor and metal wall thickness are similar and the temperature distribution tends to be similar. do.

In the next stress limit value determination step 102, a stress limit value determined from the overnight allowable life consumption corresponding to the startup mode (startup in states such as very hot, hot, warm, and cold) is determined.

In prediction time determination 103, it is determined how far in advance stress should be predicted and controlled. This predicted time is determined to be an appropriate value depending on the steam conditions generated by the boiler and the turbine startup sequence.

Steam condition change rate learning 104 is a function for grasping the state of the current boiler dynamic characteristics relative to the operating state of the turbine. Specifically, the turbine inlet steam conditions (
The objective is to understand from all actual measured values the rate at which the main steam temperature, pressure, and reheat steam, temperature) change with respect to changes in turbine speed or direct load. This learning result is used in steam condition prediction 106, which will be described later.

In operation mode determination 105, 0N10FF of circuit breaker 16
It is determined from the state whether the mode is speed control mode or load control mode, and if the former, the processing flow is switched to the speed control system 160, and if the latter, the processing flow is switched to the negative control system 140.

In the speed control system 160, the current stress estimation 161 estimates the current value of the rotor stress. This function has the following functions: first steam condition calculation 1o7, rotor surface heat transfer coefficient calculation 108, rotor temperature distribution calculation 1o9, rotor thermal stress calculation 110, and rotor stress calculation 111 considering centrifugal stress.

In the current stress level check 162, it is fully determined whether the estimated current stress is below a limit value. At this time, the stress is 1
As a general rule, the speed will be maintained even at @ places if the limit value is exceeded.

In the next calculation mode judgment 163, it is judged whether the current calculation is the time to search for the maximum acceleration rate based on the predicted calculation, and if it is the time, the process is passed to the maximum acceleration rate search 170; The tobacco processing function is bypassed and the next processing is passed to the critical speed judgment 164. In this case, the current stress estimate 16
The processing cycle of 1 is τ1, and the processing cycle of maximum acceleration rate search 170 is τ! Dechiri, τ2==n7τ1 (nT':
integer) relationship.

Maximum acceleration rate search 170 uses acceleration rate assumption 171 and stress prediction 1
72, pre-Th1l response check 173, and predicted time arrival judgment 174. Furthermore, the stress prediction 172 is composed of processing functions such as a steam condition prediction 106, a first post-death steam condition calculation 107, a rotor surface heat transfer coefficient calculation 108, a rotor temperature distribution calculation 109, a rotor thermal stress calculation 110, and a rotor stress calculation 111. There is. This maximum acceleration rate search 170 is performed using a previously prepared acceleration rate [Nl, Nt
.

・・・・・・Nx・・・・・・Np (rpm/min)]
Among them, the acceleration rate assumption 171 is assumed in descending order, and the future value of the stress that will occur in this case is predicted. First, the stress after Tl including the first post-death steam condition is pre-ff111. If this predicted stress is less than the limit value, further prediction is performed after τ1.

By repeating this process, if all the stresses do not exceed the limit values until the predicted time that has already been determined, the assumed acceleration rate is set to the maximum acceleration rate that can be achieved over the total stress. However, τ
If the predicted value exceeds the limit of 1 shift before reaching the predicted time in the process of decreasing the stress in steps of 1, the entire acceleration rate is assumed to be one rank lower, and the prediction calculation is performed again in steps of Tl from the present time. As a result of Q, if the predicted stress does not exceed the limit value, this acceleration rate is adopted.

The critical blowing speed check @164 is a function that determines whether the current speed is in the critical speed range.

The optimal speed increase rate determination 165 has a function of setting the maximum speed increase rate searched by the maximum speed increase rate search 170 in the governor 10, but if the current speed of the turbine is in the critical speed region, the speed increase rate is not changed and the previous speed increase rate is set. It has the function of continuing speed increase at a speed increase rate of . Furthermore, if the current stress estimate exceeds the limit value, this function will maintain the speed regardless of the search result for the maximum acceleration rate, but if the current speed is in the critical speed area, it will increase the speed at the same acceleration rate as before. Continue to speed up.

The speed holding time calculation 180 has a function of calculating the time until the speed increases again when the speed is maintained, and setting the calculation time in the time specification function 14.

When the speed increase is completed, the circuit breaker 16 is closed, and a load is added, the operation mode is transferred from the speed control system 160 to the load control system 140.

In the load control system 140, the current stress estimation 141 is a function of estimating the current value of rotor stress. This function includes first post-destruction steam condition calculation 107 and rotor surface heat transfer coefficient calculation 108.
, rotor temperature distribution calculation 109, rotor thermal stress calculation 11o
It is composed of the various functions of the 10-ta stress calculation 111, and these are all functions that are shared with the speed control system 160.

In the current stress level check 142, it is determined whether the estimated current stress is less than or equal to the limit value. At this time, the stress is 1
If the limit value is exceeded at any point, the load is maintained.

In the calculation mode judgment 143, it is judged whether the current calculation is the time to search for the maximum load change rate based on the predicted calculation, and if it is the time, the process is passed to the maximum negative Rj change rate search 150; If so, this processing function is bypassed and the process is passed to the next optimum load change rate determination 144. In this case, the processing cycle of the current stress estimation 141 is τ1, the processing cycle of the maximum load change rate search 150 is τ2, and τ2−==n
There is a relationship of Tτ1 (nT: integer).

The maximum load change rate search 150 is composed of the following processing functions: load change rate assumption 151, stress prediction 152, predicted stress level check 153, and predicted time arrival determination 154. Furthermore, the stress prediction 152 is composed of the following processing functions: steam condition prediction 106, first post-death steam condition calculation 107, rotor surface heat transfer coefficient calculation 108, rotor temperature distribution calculation 109, rotor thermal stress calculation 110, and rotor stress calculation 111. These are all functions shared with the speed control system. This maximum load change rate search 150 is performed using the load change rate [±Ll] prepared in advance.
, ±L2+...±Lx...±LP (%/min)]
Among these, the load change rate assumption 151 is assumed in descending order, and the future value of the stress that will occur in this case is predicted. This maximum load change rate search procedure is similar to the maximum speed increase rate procedure described above.

Optimum load change rate determination 144 is maximum load change rate search 150
It has a function to set the maximum load change rate found by ALR7 to ALR7, but if the main steam temperature or reheat steam temperature is below the specified value, the signal for load maintenance, that is, the load change rate is set to zero kALR7. do. This function also has the function of holding the load regardless of the maximum load change rate search result if the current stress estimate value exceeds the limit value.

The load holding time calculation 190 has a function of calculating the time until the load starts changing again when the load is held, and setting the calculation time in the time specification function 14.

The search signal generation 145 is a function for quickly increasing the load by giving flexibility to the learning function in the steam condition change rate learning 104 in the load increase control at the time of turbine startup.

As explained above, stress limit value determination 102, prediction time determination 103, speed control system 160 or load control system 140
If each function is operated at a period τl, control of turbine startup and normal load operation is executed. This repetitive operation continues until the system shutdown determination 112 indicates a request for system shutdown.

Next, the details of each of the above functions will be explained in order.

Fig. 3 for determining the initial temperature distribution of the mass rotor 101;
This will be explained with reference to FIG. The third section is a cross-sectional view of the rotor 40 and casing 41 of the dibiline packing section 1 viewed from the axial direction. However, regarding the intermediate pressure turbine, attention will be paid to the steam chamber wall instead of the casing 41, but since the concept is the same, only the high pressure turbine will be described here.

THCO, T)ICI, T, shown in Figure 3 now.
Tb.

Tj (j=1 to m) is the casing outer wall metal temperature, the casing inner wall metal temperature, the rotor surface temperature, the rotor bore temperature, and 1 degree for each cylinder when the rotor is divided into fm virtual coaxial cylinders.

Although it is difficult to actually measure the temperature distribution of the rotor, it is particularly important to accurately set the initial value for this system, which aims at rapid startup and rapid load changes.

FIG. 4 shows the specific processing contents of this initial temperature distribution determination 101.

When this system starts operating, it estimates the temperature distribution in the radial direction inside the rotor from the actually measured casing inner and outer wall temperatures THcx and Ty+co. In this case, TS, Tb
is, T,=T■cI・・・・・・・・・(1)Tb=THc
++kT (Tico Ticx) --- (2) is assumed. kT in the above equation (2) is a constant determined by the shape of the turbine. The internal temperature distribution is regarded as a value obtained by interpolating Ts and Tbk-order, and is expressed by the following equation.

Further, B in the figure is a variable indicating the magnitude of the temperature gradient in the radial direction inside the rotor. If the gradient is large, the error in estimating the temperature distribution will also be large. When the temperature difference between the inner and outer walls of the casing is larger than the specified value ΔT, B-1, and when it is smaller, B = O.
shall be. Furthermore, if the current speed Nα is larger than the specified value N9, the estimation error may become large even if the temperature difference is small, so B=1. This value of B is for reference in the next processing function, stress limit value determination 102.

Next, when the circuit breaker 16 is in the OFF state, that is, each process and function of the speed control system 160 will be specifically explained.

First, the current stress estimation 161 will be explained. As mentioned above, this processing function is also used in the load control system, including the first post-death steam condition calculation 107, rotor surface heat transfer coefficient calculation 108, rotor temperature distribution calculation 109, rotor thermal stress calculation 110, and rotor stress calculation 111. It consists of functions.

A step-by-step explanation will be given below.

The first post-death steam condition calculation 107 is a function that calculates the first post-death steam temperature and pressure of the high-pressure and intermediate-pressure turbines from arbitrary main steam conditions, turbine speed, speed increase rate, load, and reheat steam temperature. In operating conditions where the steam flow rate is small, such as during speed increase and low load, it is difficult to measure the first post-death steam temperature and pressure of the high-pressure and intermediate-pressure turbines with high accuracy.

Also, relying on actual measurements makes it difficult to make highly accurate predictions.

FIG. 5 shows a calculation procedure for uniquely estimating from the steam conditions generated by the boiler and the operating state of the turbine in order to solve this problem. This estimation method is based on main steam temperature TMS, pressure P
By using Ms, reheat steam temperature Tua, speed N1, acceleration rate K, and load as input variables, p can be used consistently from startup to normal load operation.

However, for safety reasons, the steam temperature after the first stage of the intermediate pressure turbine is assumed to be the actual value of the reheat steam temperature assuming that there is no temperature drop due to the first stage. The meanings of the symbols used in FIG. 10 are as follows.

N: Speed (“door”) No: Rated speed (Union) Meat - Speed increase rate (Hayabusa/min) L: Load (%) L’: Equivalent load under rated steam conditions (%) Ll:
Boundary load between full-circle injection and mixed injection (%) L2: Boundary load between partial injection and mixed injection (%) TM11: Main steam temperature (c) TRH: Reheat steam temperature (U) TMSR: Rated main steam temperature (c ) Tt': High-pressure turbine first post-death steam temperature relative to L'
(c) ΔTo: Temperature drop between the main steam temperature and the steam temperature in the high-pressure turbine bowl (r) ΔTRO: ΔTo (tZ') Tul under rated steam conditions
: High-pressure turbine first post-death steam temperature (c) T! ,: Intermediate pressure turbine first post-death steam temperature (tjPMs,: Main steam pressure (ata) PXo: High-pressure turbine first post-death steam pressure equivalent to no-load operation (ata) P former R: High-pressure turbine first post-death steam at rated load pressure (
ata) PtlB: Steam pressure after the first sinking of the intermediate pressure turbine at rated load
(at'a) Pal: Steam pressure after the first stage of the high pressure turbine (ATA) PH: Steam pressure after the first stage of the intermediate pressure turbine (ATA) Kl: Adjustment valve throttling rate (always set to 1 = 0 during partial injection) (ata) K2: Temperature reduction coefficient KNL due to the first stage of high-pressure turbine:
High-pressure turbine first post-death steam pressure equivalent to no-load loss at rated speed (ata) KAc: High-pressure turbine first post-depletion steam pressure equivalent to acceleration (
ata/(Unit)2/min) k: No-load loss index The processing contents of the rotor sloppy heat transfer calculation 108 are as shown in FIG. Focus on. However, although FIG. 6 shows a high-pressure turbine, the heat transfer coefficient is also calculated using the four-ball procedure for an intermediate-pressure turbine. The meanings of the symbols used in this diagram are as follows.

N: Speed (vomit) TFI! : High-pressure turbine first post-death steam temperature (c) Pa
l: Steam pressure after high pressure turbine first death (ATA) λIIIT: Steam thermal conductivity after high pressure turbine first death (1
01/yi -C-(8)) ν1[IT: High-pressure turbine first crotch rear steam kinematic viscosity coefficient (
rr? /Sem1) γIIIT: High-pressure turbine 1st post-death steam specific weight (edge/
m゛) FSL': Labyrinth packing leakage flow rate (Ky/ge
o) FsLv: Labyrinth packing volume leakage flow rate (de/(
8)) UAX: Labyrinth packing axial leakage flow velocity (m/(
8)) URD: Labyrinth packing rotor surface speed Cm1) U: Labyrinth packing combined leakage flow speed Cm/Sec
) R: Winolds number N1: Nutsselt number K Nirotor surface heat transfer coefficient (kcal/m7・C-(
8)) Ko: Constant determined by the turbine shape δ: Gap of labyrinth packing (m) d - Rotor surface diameter (rn) Z: Number of fins of labyrinth packing A: Gap surface of labyrinth packing tt (m') rs
: Rotor surface radius (m) PH2: Pressure after the second stage of the high pressure turbine (ata) However, in Fig. 11, the pressure ratio after the first stage and after the second stage (P2
/Pi) is the operating state of the turbine, i.e. speed, speed increase rate,
Even if the load is expressed as a formula, it can be considered to be approximately constant, so it is actually calculated as a constant.

Next, the rotor temperature distribution calculation 109 will be explained using FIG. 7. The heat movement inside the rotor is considered to be a one-dimensional flow consisting only of the radial direction, so the rotor is divided into 6m virtual cylinders as shown in Figure 7, and the temperature distribution is calculated by focusing on the heat balance between each cylinder. Melt. The time step size for heat balance calculation is τl
Then, Qt, s is the amount of heat transferred from the steam to the rotor surface during T1, QGI+ is the amount of heat transferred from the rotor surface to the center of the outermost cylinder, and Qj+ 1+1 is the amount of heat transferred from the jth cylinder to the j+14th cylinder. It is the amount of heat conducted. However, since the bore is in an insulated state, Q is always present. ,. . 1
=0. Now, if the current time is t, the time is 1τl
The amount of heat transfer that occurs between each cylinder during the period from t to 71 is
Each is expressed as follows.

Qt , r (t)−2πrt K(t) (T)It
(t)-T3 (t-T1))τl・・・・・・・・・
(4) ・・・・・・・・・(tongue) ・・・・・・・・・(su・・・・・・・・・ (+?) Q□+-=+t(j)=O (9) Here, λM is the thermal conductivity of the rotor material.

From the relationship Qf,5(t)-Qy,t(t), Ts(t
-T) is expressed by the following formula.

, , , , , , ('0 where r' = 4 r2 + 3Δr W(t) = ΔrK(t)/λM) The amount of heat ΔQ s (t) accumulated in the 'th cylinder is ΔQ
j(t)=Qj−t, +(t), Q+, +
+t (t) ・・・・・・・・・(Since it is expressed as 1, the temperature TI of the j-th cylinder is expressed by the following formula.T+(t)−T+(t−It)+ΔQ”(t )/v+ρ
UCM・・・・・・・・・(11) Here, vj: Volume per unit length of the j-th cylinder ρ■−
Rotor material density CM−rotor material specific heat Also, the rotor bore temperature Tb(t) is expressed by the following equation by approximating the temperature distribution by a quadratic equation.

FIG. 8 shows details of the non-processing function described above.

Next, rotor thermal stress calculation 110 will be explained.

The rotor thermal stress, that is, the rotor optical surface thermal stress σ8 and the rotor bore thermal stress σBT, are expressed by the following equations based on the temperature distribution obtained by the rotor temperature distribution calculation 109 described in 11.

Here E: Young's modulus of rotor material α: Linear expansion coefficient of rotor material ν: Boannon ratio of rotor material T6: Rotor surface temperature Tb: rotor bore temperature TM: Rotor volume average temperature Note that the rotor volume average temperature TM is expressed by the following equation.

TM=ΣT+(rl"-rl"+1)/("js"-r
)) +...(l!;)1- Next, rotor stress calculation 111 that also takes centrifugal stress into consideration will be explained. Since the centrifugal stress is proportional to the square of the turbine speed N, the centrifugal stress σBc acting on the bore at the speed N is expressed by the following equation, where σBCR is the rated speed 'kNo' and the rated speed core stress is σBCR.

Therefore, the bore stress σB is σB−σBT+σBC (17). 7t Also, on the rotor surface, stress is concentrated due to the surface shape υ, and the direction of action of thermal stress is the axial direction. Considering that the centrifugal stress is in the circumferential direction, both act in directions perpendicular to each other. Therefore, regarding the rotor surface stress, it is sufficient to consider only the thermal stress for which life consumption is a problem, and the rotor surface stress σB becomes σ B = σ8T . . . Cls.

This completes the explanation regarding the current stress estimation 161.

The next current stress level check 162 is performed using the above σS, σ
This is a function to determine whether or not B exceeds the stress limit value set in the stress limit value determination 102 described above.

The next calculation mode judgment IIfr 163 is a function of determining whether or not the current calculation is the time to perform a search for the maximum acceleration rate based on the predicted calculation. In other words, if it is specified that the prediction calculation is to be performed once every 0 times, the processing function 19 has the ability to bypass the maximum acceleration rate search 170 n -1 times out of n diagrams. - Next, the maximum acceleration rate search 170 will be explained.

This processing function uses the current time as a reference and predicts the predicted time pointer 1.
The stress occurring on the rotor surface and rotor bore until after the predicted time tP determined in step 03 is predicted in time step width (τ1), and each time it is compared with the stress limit value, and the stress during this period exceeds the limit value. This is a function that searches for the maximum acceleration rate. The acceleration rate here is based on the acceleration rate assumption 171,
This is selected from a plurality of acceleration rates prepared in advance. The plurality of acceleration rates are passed to the acceleration rate assumption 171 and to the stress prediction 172 in order from the highest to the highest. With the processing function of this stress prediction 172, it is possible to change the current time to υτ.
The stress on the rotor surface and bore after 1 is predicted and compared with the stress limit value in a predicted stress level check 173. As a result of this comparison, if the stress of both is less than the limit value, the stress prediction is returned to 1.72, and then the entire stress after rl is predicted. In this way, the stress is predicted at 71 intervals until after 1P for a given acceleration rate assumption value Nx, and compared with the jjijl limit value, but if either the rotor surface stress or the bore stress exceeds the limit value. In this case, the process is performed based on the acceleration rate assumption 171
Return to normal, change the assumed acceleration rate, and predict the stress in the same way. In this case, the assumption of the acceleration rate is made in ascending order, and in the predicted time arrival judgment 174, if the stress prediction value for the assumed acceleration rate value does not exceed the limit value over the period 1P, the assumed acceleration rate at this time is set to the maximum value. Decide as the acceleration rate and complete the search. If the stress exceeds the limit value for all the assumed values of the acceleration rate, the acceleration rate is set to zero as the maximum acceleration rate search result. Note that the processing content of the stress prediction 172 is the above-mentioned current stress estimation 1.
It is similar to that of 61. The difference is that the predicted fI is used instead of the current cage as the turbine inlet steam condition;
The point is that the speed is not the current value but a predicted value corresponding to the assumed value of the acceleration rate.

In order to predict the turbine inlet steam conditions, we learned the ratio of the amount of change in steam conditions to the amount of load change. Use the results. That is, the time rate of change in main steam temperature with respect to the assumed value Nx of the speed increase rate is expressed by the following equation.

. . . GuIQ) Next, the speed holding time calculation 180 will be explained with reference to FIG. First, in speed retention determination 181, it is determined whether or not speed retention is necessary, and if speed retention is not required, the processing of speed retention calculation 180 ends. If the speed is maintained, a predicted stress value is calculated in predicted stress calculation 182. This calculation is similar to the stress prediction 172 in FIG. Consists of processing functions. In the predicted stress determination 183, it is determined whether the predicted stress is below the allowable value, and the predicted stress needle 418 is turned until the predicted stress becomes below the allowable value.
2 (disturb).

In the speed holding time calculation 184, as shown in Fig. 10, if the sampling period for the predicted stress calculation is τ, the stress exceeds the allowable value at the time of 0th block and falls below the allowable value at the time of the predicted stress value (n+3)τ. In this case, the estimated holding time is 3 guns.

In addition, when the predicted stress value exceeds the allowable value and is held, the time during which the predicted stress value predicted at the minimum acceleration rate exceeds the allowable value can be considered as the holding time, as shown in FIG. The retention time output function 185 outputs the retention time to the time specification function 14.

The time display function indicates the time using various methods such as a digital display using a light emitting diode or plasma display, printing by a typewriter, or display using a CRT display.

Since the steam conditions from the boiler usually deviate from the planned values, it is necessary to calculate the holding time repeatedly during the holding operation so that it can correspond to the operating conditions.

As explained above, when the stress exceeds the allowable one shift and the shift is made to the holding operation, the estimated value of the holding time can be revealed moment by moment and notified to the operator. In particular, since the time required for stress to be below the allowable value changes depending on the steam temperature and pressure on the boiler side, the required holding time can be calculated and calculated from the current time at any time, making it possible to carry out operations in a planned manner. .

Next, each processing function of the load control system 140 when the circuit breaker 16 is in the ON state will be specifically explained.

In the load control system 140, current stress estimation 141, current 1
The processing methods of 5-level level check 142, calculation mode judgment 143, and maximum load change rate search 150 are basically the processing functions 161, 162, and 1 of the speed control system 160, respectively.
63,170. However, the only difference is that in the speed control system 140, the speed increase rate is the target of the maximum value search, whereas in the load control system 160, the load change rate is the target of the maximum value search.

Load change rate assumption 15 in maximum load change rate search 150
1 assumes that if the load request LR is a load increase request for the current load, it is assumed in order from the largest load change rate among multiple load change rates prepared in advance; Assumptions are made in descending order of the ratio.

The load holding time calculation 190 has the same function as the speed holding time calculation.

Next, the optimum load change rate determination 144 will be explained. τ at maximum load change rate search 150! Set the load change rate kALR7, which is searched at the cycle of , and modify it.
If the current stress exceeds the stress limit value during the first period, this function immediately holds the load.

〔Effect of the invention〕

According to the present invention, starting from the turbine inlet conditions, the speed increase rate and load change rate of the turbine are successively optimized based on the prediction of the rotor stress, and at the same time, when transitioning to holding operation, the stress prediction value is The holding duration from the current time can be obtained in real time, and the future operation schedule can be effectively shown to the operator, so that planned operation can be carried out.

[Brief explanation of drawings]

FIG. 1 shows the relationship of input/output signals between the thermal stress predictive turbine/visual control system of the present invention, the related control system, and the plant. FIG. 2 shows a processing procedure in the supervisory control system of the present invention. Figure 3 shows the rotor after the first stage of the turbine, -,? and the cross section of the casing and its temperature state. Figure 4 shows the initial stage of the rotor! , a method for determining the S degree distribution is shown. FIG. 5 shows a method for estimating the first post-decay steam condition. FIG. 6 shows a method for calculating the heat transfer coefficient of the labyrinth packing. FIG. 7 shows the concept of heat balance between the virtual divided circular nodes of the rotor. FIG. 8 shows a specific calculation procedure for rotor temperature distribution. FIG. 9 shows the processing procedure for calculating retention time. 10th
The figure shows the holding time when the current stress exceeds the allowable value, the first
Figure 1 shows the retention time when the predicted value was exceeded. 100...Thermal stress prediction turbine control system, 2o. ...High pressure turbine, 300...Intermediate pressure turbine, 4o
. ...Low pressure turbine, 500... Generator, 1... High pressure first post-subdued labyrinth packing part, 2... Medium pressure first post-subdued labyrinth packing part, 3... Bore (center hole), 4
...optimum speed increase rate, 6...optimum load change rate, 7...
A.L.R. 8... Instantaneous target speed, 9... Instantaneous target load, io・
... Governor, 11... Adjustment valve, 12... Actuator, 13... Valve position command, 14... Time display function, 15... Holding time, 16... Circuit breaker', 17...・
- Breaker 0N10 F F status, 18...Load request value, 19...Speed, 20...Main steam, 21...Reheat steam, 22...Adjustment valve position, 23...Main steam pressure,
24...Main steam temperature, 25...Reheat steam temperature, 26
...Temperature of the outer wall of the casing after the first stage of the high-pressure box, 2.7...
Temperature of casing inner wall after high pressure 1st stage, 28...High pressure 1st
Post-stage steam pressure, 29... Medium pressure steam chamber outer wall temperature, 30.
... Medium pressure steam indoor wall temperature, 40 ... Casing, 41
...Rotor, 140...Load control system, 160...
Speed control system, 150...Maximum load change rate search, 170
...Maximum acceleration rate search, 180...Speed holding time, 1
90... Load holding time calculation, 101... Initial temperature distribution determination, 102... Stress limit value determination, 103... Prediction time determination, 104... Steam condition change rate learning, 105
...Operation mode judgment, 106...Steam condition prediction, 1
07... First steam condition calculation, 108... Rotor surface heat transfer coefficient calculation, 109... Rotor temperature distribution calculation,
110... Rotor thermal stress calculation, 111... Rotor stress calculation, 112... System stop+h judgment, 141...
- Current stress estimation, 142...Current stress level check, 143...Calculation mode judgment, 144...Optimum load change rate determination, 151...Load change rate assumption, 152...
・Stress prediction, 153...Predicted stress level check, 1
54... Judgment of arrival of predicted time, 161... Current stress estimation, 162... Current stress level check, 163...
・Calculation mode judgment, 164... Critical speed judgment, 165
...Optimum acceleration rate determination, 171...Acceleration rate assumption, 17
2... Stress prediction, 173 river predicted stress level check,
174... Predicted time arrival judgment, 181... Speed retention judgment, 182... Predicted stress calculation, 183... Predicted stress judgment, 184... Speed retention time calculation, 185...
3rd figure, 4th figure, 7th figure, 10th country protection power

Claims (1)

[Claims] 1. Applicable to power generation equipment consisting of a working fluid generation source for driving a turbine, a valve that controls the flow rate of the working fluid generated from this source, a turbine operated by the fluid, and a generator mechanically connected to this. In the fl control system of power generation equipment, which calculates the stress generated in the turbine due to a change in the state of the working fluid and operates according to the calculated stress, it has a means for predicting the stress generated in the turbine rotor, and the turbine 1. A rotor stress prediction turbine monitoring and control system comprising means for determining a holding duration time from the stress predicted value when the operating state is maintained.