JPH04140402A - Steam turbine controller - Google Patents

Abstract

PURPOSE:To prevent variation of the turbine inlet steam pressure and prevent the unnecessary scramming trouble due to the pressure increase in a nuclear reactor by controlling the TBV opening degree in the opening direction at the speed nearly equal to the opening direction operation speed of the actual CV opening degree when the CV opening degree instruction value sharply varies in the opening direction. CONSTITUTION:The steam generated in a nuclear reactor 1 flows into a turbine 4, passing through a main steam stop valve 2 and a steam control valve CV3, and is condensed in a condenser 5. Further, a portion of the steam bypasses the turbine 4, passing through a turbine bypass valve TBV 6 from the front part of the main steam stop valve 2, and is introduced into the condenser 5. In this case, the limit value corresponding to the actual CV opening speed is set in a variation rate limiter 23, and the signal v15 which is obtained by adding the variation rate limit value corresponding to the CV actual opening speed to the variation of the opening direction of the inputted CV opening degree instruction value v8. Further, an adder 24 subtracts the output signal v15 of the variation rate limiter 23 from the CV opening degree instruction value v8, and outputs a deviation signal v15. This deviation signal v15 corresponds to the difference between the CV opening degree instruction value v8 and the actual CV opening degree, and is added into an adder 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a steam turbine control device in a power plant.

(Prior Art) FIG. 4 shows an example of a turbine system in an atomic coupler.

In FIG. 4, steam generated in a nuclear reactor 1 passes through a main steam stop valve 2 and a steam control valve (hereinafter referred to as Cv) 3, flows into a turbine 4, drives the turbine, and is condensed in a condenser 5. be done. Further, some of the steam passes from before the main steam stop valve 2 through a turbine bypass valve (hereinafter referred to as TBV) 6, bypasses the turbine 4, and flows into the condenser 5. The main steam stop valve 2 is normally kept fully open, and the valve openings of the CV3 and TBV6 are adjusted to control the turbine inlet steam pressure and turbine speed.

In this case, the actual pressure and actual speed are detected by a pressure detector 7 provided before the main steam stop valve 2 and a speed detector 8 attached to the turbine shaft, respectively.

A functional block diagram of a conventional steam turbine control device is shown in FIG.

In FIG. 5, the set speed set by the speed setting device 9 and the actual speed detected by the speed ratio device 8? /2 is subtracted by the adder 10, and the velocity deviation V, (=V.

z'z) is output as the speed control command value. On the other hand, the set pressure V4 set by the pressure setting device 11 and the pressure detector 7
The actual pressure v5 detected in is subtracted by the adder 12, and the pressure deviation Vb (=fs #4) is taken out via the phase corrector 13 as the pressure control command value V7.

The speed control command value V3 and the pressure control command value y7 are input to the low value selector 14, and the lower command value is selected and the Cv
Opening command value? , and is compared with the actual opening signal V9 of CV3 detected by the valve position converter 5 by the adder 16, and the deviation ? 1o (=?e #s)
is the valve opening command value V of CV3 via the valve driver 17.
On the other hand, the pressure control command value V,
and the Cv opening command value V8 are subtracted by the adder 18, and the difference (=V7'tr s ) is output as the TBV opening command value V□1, and the TBV6 detected by the valve position converter I9 is
The adder 20 compares the actual opening degree signal V□2 of
The valve opening of BV6 is controlled in accordance with the opening command value V□.

Using the above control device, the following pressure control operation is normally performed. In pressure control operation, the above speed control command value V
The set speed V□ is set high so that 3 is slightly higher than the pressure control command value V7, and the pressure control command value V7 is selected as a low value to become the CV opening command value V.

I am trying to make it so that

Therefore, the pressure control command value v becomes the CV opening command value V9, and the TBV opening command value V0. becomes zero, TBV6 becomes fully closed, and pressure control is performed only by CV3.

When the actual speed 1r2 increases during pressure control operation, the speed control command value decreases and the pressure control command value ji becomes lower, so the Cv opening command value 98 becomes the speed control command value V,
The Cv opening degree is controlled in the closing direction.

At this time, pressure control command value 1□>CV opening command value V, so TBV opening command value Vx1>O, and TBV6
is controlled in the opening direction. In other words, by closing Cv3, the amount of steam flowing into the turbine 4 decreases, and the excess steam is transferred to the TBV.
6, the steam flow rate as seen from the reactor 1 is constant, and the steam pressure at the inlet of the turbine 4 is also constant.

(Problem to be Solved by the Invention) As mentioned above, during normal pressure control operation, even if the actual speed or actual pressure changes, the opening degrees of CV3 and TBV6 follow their designated values without delay, so this is a problem. However, when a sudden disturbance occurs due to a system accident, the following problems occur.

That is, as shown in the time chart of FIG. 6, if the actual speed 1r suddenly increases from the reference speed at time t1 during pressure control operation, the speed control command value V.

From time t2 when the speed control command value irz<pressure control command value V7 decreases, the Cv opening command value V decreases to CV3.
The actual opening signal V, is also decreased, and at the same time TBV6(7)T
BVR degree command value 1. increases, and the actual opening signal Z'12 of TBV6 also increases together with the TBV opening command value V□1.

In this case, the closing operation amount of CV3 and the opening operation amount of TBV6 are equal in magnitude, so the actual pressure of the turbine is V.

However, when the actual speed V2 suddenly returns to the reference speed at time t4, C■ Opening command value ㅅ,
changes in the opening direction, while the TBV opening command value V changes in the closing direction.

In this case, the change speed and opening/closing amount of both opening command values y,, #, are the same, but the actual opening speed of CV3 and closing speed of TBV6 are different, and TBv6 closes faster. , steam from the reactor 1 is restricted and the inlet steam pressure of the turbine 4 increases.

Therefore, the pressure control command value V7 is in the opening direction, and TB
V6 starts to open at time t7 and becomes fully open at time t, but at this point the actual pressure V5 exceeds the control value, and there is a possibility that the reactor protection interlock will operate and lead to a reactor scram.

As a countermeasure to this, the opening speed of Cv3 is changed to a Cvv degree command value of 11.
There is a way to make Cv3 follow quickly, but since the time difference between opening time t and t5 is short, less than a few seconds, increasing the opening speed of Cv3 may cause thermal stress problems in the components on the turbine 4 side. On the other hand, there are also limitations on the response of the hydraulic system that operates Cv3, making it difficult to increase the opening speed.

Therefore, an object of the present invention is to provide a steam turbine control system that controls the TBV closing speed by following the Cvv opening degree when a Cv sudden opening command is input, and thereby suppresses fluctuations in the turbine inlet steam pressure. The goal is to provide equipment.

[Structure of the invention]

(1 [Means for Solving the Problems]) The present invention controls the opening degree of a steam control valve that adjusts the flow rate of steam flowing into a turbine and a turbine bypass valve that adjusts the flow rate of steam that bypasses the turbine. In a steam turbine control device that controls speed and turbine inlet steam pressure, calculate the deviation between the steam regulating valve opening command value and the steam regulating valve opening command value plus a rate of change limit corresponding to the steam regulating valve actual opening speed. The present invention is characterized in that means is provided for adding the deviation to the BPV opening command value.

(Function) By providing the above means, even when the Cvv open command is input, the BPV opening command is added with the deviation between the Cvv degree command value and the Cvv opening degree, so it follows the CV actual opening speed and closes. Therefore, it is possible to prevent fluctuations in the turbine inlet steam pressure due to a mismatch between the Cv opening degree and the BPV opening degree.

(Example) An embodiment of the present invention is shown in FIG.

In the configuration of FIG. 1, the same parts as those shown in FIG. 5 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 1, a limit value corresponding to the CV actual opening speed is set in the change rate limiter 23, and a limit value corresponding to the CV actual opening speed is set for the change in the opening direction of the input CV opening command value y. Outputs the signal V, which is the addition of the rate of change limit value 6. In addition @24, the rate of change limiter 2 is output from the CV opening command value V.
3 and outputs a deviation signal y+,s. This deviation signal yxs is the Cv opening command value V, and C
Corresponds to the deviation of VV opening.

The deviation signal V□ is applied to an adder 18.

The effects of the two above-mentioned configurations will be explained below with reference to FIG.

During pressure control operation, when the actual speed V2 starts to rise at time t□, the pressure control command value v7 becomes greater than the speed deviation V at one time t2, and the CV opening command value V changes in the closing direction, causing the actual speed of Cv3 to change. The opening signal V9 also changes in the closing direction following the Cvv degree command value of 1°. At this time, pressure control command value F t > CV
Since the R degree command value changes, the TBV opening command value V □ moves in the opening direction, and the TBV 6 moves in the opening direction.

Next, when the actual speed 91 begins to return to the reference value at time 9, t,
Although the Cv opening command value V changes in the opening direction, the opening operation of Cv3 does not follow the change in the CV opening command value V.
The actual opening signal V of Cv3 changes in the opening direction with a delay from the C■ opening command value vIl.

At this time, the output signal TL5 of the change rate limiter 23 is a signal obtained by adding a change rate limit corresponding to the CV actual opening speed to the C■ opening command value U, so the change is similar to the actual opening signal 119. and the deviation between the Cv opening command value V# and the output signal V15 of the rate of change limiter 23? /1. occurs as shown in Figure 3.

This deviation signal v16 is sent to the adder 18 as the BPV opening command value V.
, 7, so the BPV opening command value -V□7
follows the actual opening degree signal V of Cv3 and changes gently in the closing direction.

Thus, as the actual speed V2 of the turbine 4 decreases, Cvv
Even if the degree command value S suddenly changes to the opening direction, Cv3
It becomes possible to follow the actual opening degree change and control the TBV 6 in the closing direction.

Further, another embodiment of the present invention will be described with reference to FIG.

In FIG. 2, the deviation signal V□ in FIG. 1 is converted into a rate-of-change limit permission signal 1. A contact point 25 is provided so that the addition is made to the adder 18 only when .

As the rate of change limit permission signal J, 8, when pressure control medium outside is given and pressure control medium outside is selected, the input of the deviation signal yxt to the adder 18 is cut off.

During pressure control, control is possible without impairing the controllability of TBV6.

〔Effect of the invention〕

As explained above, according to the present invention, even if the Cv opening command value changes rapidly in the opening direction, the TBV opening is controlled in the closing direction at a speed comparable to the operating speed in the opening direction of the CV actual opening. The total flow rate of steam flowing to Cv and TBV does not change, and the turbine inlet steam pressure does not change.

Therefore, according to the present invention, an excellent effect is achieved in that unnecessary scram accidents due to a rise in reactor pressure are prevented.

[Brief explanation of the drawing]

FIG. 1 is a functional diagram showing one embodiment of the present invention;
The figure is a functional block diagram showing another embodiment of the present invention, FIG. 1 is a time chart showing the operation of FIG. 1, FIG. 4 is a configuration diagram showing a conventional turbine system, and FIG. A functional block diagram showing an example of a steam turbine control device, FIG.
5 is a time chart showing the operation shown in the figure. 3... Steam control valve 6... Turbine bypass valve 10, 12.18.24... Adder 14... Low value selector 23... Rate of change limiter 2
5...Contact Agent Patent Attorney Rules Noriyuki Chika Diagram Diagram Diagram Diagram Diagram

Claims (2)

[Claims] (1) Means for comparing the input pressure control signal and speed control signal, selecting the lower value and controlling the steam adjustment valve opening as a steam adjustment valve opening command signal, and In a steam turbine control device having means for subtracting a steam regulating valve opening command signal and controlling the turbine bypass valve opening as a turbine bypass valve opening command signal, an opening direction change rate of the steam regulating valve opening command signal is provided. a rate of change limiter that limits the rate of change so that the rate of change does not exceed the actual opening speed of the steam regulator, and a deviation calculator that calculates a deviation between the output signal from the rate of change limiter and the steam regulator opening command signal. . A steam turbine control device, further comprising means for adding an output signal of the deviation calculator to the turbine bypass valve opening command signal. (2) The steam turbine control according to claim 1, further comprising a circuit that excludes addition of the output signal of the deviation calculator to the turbine bypass valve opening command signal while the turbine bypass valve is under pressure control. Device.