JP2965658B2 - Turbine control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a turbine control method for a power plant having a steam turbine.

(Prior Art) Generally, a control method of a steam turbine is performed by adjusting an opening degree of a steam control valve (hereinafter abbreviated as CV) of a steam amount flowing into the steam turbine.

FIG. 7 is a configuration diagram of a conventional turbine control device. During normal operation, setting devices set by the operator for turbine control include a load limit setting device 1 and a governor setting device 2.

An output reference value of the turbine is set in the governor setting device 2, and an operation is performed such that the rotation speed of the turbine becomes constant. In other words, to obtain a speed deviation signal S ₃ by adding the actual turbine speed S ₂ with the reference speed setting values S ₁ set by the reference speed setter 9 by an adder 10. This speed deviation signal S ₃ is inputted to the speed control coefficient unit 11, to set the opening / closing ratio of CV opening for the speed deviation and outputs a speed control signal S _4. Then, obtain the acceleration control signal P ₃ are added by the governor setting value P ₂ and the speed control signal S ₄ and the tone adder 3 set the governor setter 2.

And the governor control signal P ₃ and the load limit setting value P ₁ set in the load limit setting device 1 is inputted to the low value selector 4, lower signal ones of both are selected. This selection signal P ₈
It becomes a CV opening command signal for adjusting the CV opening.

Thus, load operation by the set output reference value to the governor setting unit 2 (the load reference value) is carried out by setting a load limit setting value P ₁ to a value higher than the speed governor control signal P _3. On the other hand, the set load limiting operation to a load limit setting device 1, takes place the governor control signal P ₃ set the governor setting value P ₂ to be higher than the load limit setting value P _1.

As described above, in the load operation by the governor setter ₂ , control is performed to keep the turbine output constant at the governor set value P2 and also to keep the turbine speed constant. In the limited operation, constant operation of the turbine output is performed without performing constant control of the turbine speed. Therefore, constant control of the steam flow rate is achieved.

In turbine output constant operation, but sets the governor setting value P ₂ to be higher than the load limit setting value P _1, if you set too high value, the generator power system as load shedding When the turbine speed greatly increases due to a large load loss such as disconnection, the CV closing control is delayed and the overspeed amount increases. Therefore, generally so that in such a manner that a governor setting value P ₂ to a value slightly higher than the load limit setting value P _1, automatically follow the change in the load limit setting value P _1.

The automatic follow-up, the load limit setting value P ₁ and the governor setting value P ₂
Enter the door to the adder 5 outputs the real tracking width signal P _4.

The signal limiter 8 taking deviation and tracking width setting value P ₅ set in track width setting unit 6 and the actual track width value P ₄ by the adder 7
Input to, and inputs the output P ₇ governor setter 2 having integration function. The signal limiter 8 limits the rate of change of the integration speed of the governor setting device 2.

FIG. 8 shows this automatic tracking operation. Time from time t ₀
until t ₄ are in accordance with the change in the load limit setting value P ₁ governor setting value
P ₂ has indicates that the automatic follow-up with the width of the track width setting value P _5, since at this time the turbine speed S ₂ is the reference value constant, the governor control signal P ₃ is governor setting value It is equal to P _2. Also, CV opening degree command signal P ₈ is the load limit setting value
Because of low value selection of P ₁ Doo governor control signal P _3, During the time t ₄ from time t _0, the value of the load limit setting value P ₁ is outputted. When the turbine speed S ₂ soared now time t _5, the speed control signal S ₄ is rapidly decreased, CV opening governor control signal P ₃ becomes smaller than the load limit setting value P ₁ command signal P ₈ is sharply, narrowing of CV opening is performed. Further, when a change in load limit setting value P ₁ between time t ₇ from the time t ₆ in this state, since the governor setting value P ₂ varies automatically following, the governor control signal P ₃ and CV opening command signal P ₈ changes as well.
When the turbine speed S ₂ is rapidly returns to the reference value at time t _8, the governor control signal P ₃ to a value of the governor setting value P ₂ at that time, rapidly increases.

Thus, CV opening degree command signal P ₈ is the movement to rapid opening CV is a rapid increase to a value of the load limit setting value P ₁ at that time.

(Problems to be Solved by the Invention) As described above, since the automatic following of the load limit setting device in the governor operation is automatically performed by a signal including the speed control signal, the following change of the load limit setting in the CV closing direction is performed. If the rate is increased, the load limit setting unit closes following the CV closing due to the frequency increase, and the rate of change in the CV opening direction at the time of frequency recovery can be limited.

However, in the automatic follow-up of the governor setter in the load limiting operation, since the automatic follow-up is performed using a signal that does not include the speed control signal, the CV opening cannot be limited when the speed control signal changes, as described above. When the turbine speed suddenly changes
Since the CV opening changes suddenly, the amount of steam to the CV changes suddenly. Particularly, in the direction in which the valve rapidly opens, thermal fatigue occurs in the valve and the turbine main body, and the life is consumed, which is not preferable for the valve and the turbine main body.

Further, since the supply of steam suddenly fluctuates also on the steam generation source side, there is a problem that the control on the steam generation source side becomes unstable.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a sudden opening of a steam control valve when the turbine speed is rapidly reduced and the steam control valve is rapidly opened, and to control the opening of the steam control valve according to an allowable change width and change rate, thereby controlling the turbine and the steam control valve. An object of the present invention is to prevent thermal fatigue of a valve and prevent control instability on the steam generator side.

[Structure of the Invention] (Means for Solving the Problems) A turbine control apparatus according to the present invention is a turbine control apparatus which adds a steam turbine speed control signal to a governor setting signal from a governor setting device for setting a steam turbine output reference value. Turbine control in which a speed control signal and a load limit setting signal from a load limiter for setting an output upper limit value of a steam turbine are applied to a low value selector, and a lower signal is selected to be a signal for operating a steam control valve. In the apparatus, an adder for adding a follow-up width setting signal for setting a difference between a governor setting signal from a governor setting device and a load limit setting signal from a load limiter to the speed control signal, and A change rate limiter for limiting the change rate of the addition signal is provided, and the change rate limit signal from the change rate limiter is added to the low value selector, whereby the load limit set value, the speed control signal, It is characterized in that the operation signal of the steam control valve to select the lowest signal of the three signals of rate limiting signal.

In this case, an adder may be provided after the rate-of-change limiter, and the tracking width setting signal may be added to the output of the rate-of-change limiter and added to the low value selector.

Further, the turbine control device of the present invention includes a governing control signal obtained by adding a speed control signal of the steam turbine to a governor setting signal from a governor setting device for setting an output reference value of the steam turbine, and a steam turbine output upper limit value. A load limit setting signal from the load limiter to be set is added to the low value selector, and the governor setting signal from the governor setting device is selected in the turbine control device that selects the lower signal and operates the steam control valve. An adder for adding a follow-up width setting signal for setting a difference from the load limit setting signal from the load limiter to the output signal of the low value selector; and limiting a rate of change of the added signal from the adder. A rate-of-change limiter, and a second low-value selector that receives the output signal of the rate-of-change limiter and the output signal of the low-value selector and selects and outputs a low signal of the two. This second low Configuration the output signal of the selector and an operation signal of the steam control valve also may take.

Also in this case, an adder may be provided after the rate-of-change limiter, and the tracking width setting signal may be added to the output of the low value selector and added to the second low value selector.

(Operation) When the operation signal selected as the smaller of the output value of the governor setting device and the output value of the load limiter is the opening direction operation signal of the steam control valve, the operation signal changes. Is limited, and the limited operation signal is applied as a drive control signal for the steam control valve. As a result, the steam control valve does not operate at a change rate larger than the change rate limit value, so that the steam control valve opening does not increase rapidly.

(Embodiment) FIG. 1 shows an embodiment according to the present invention. The same components as those shown in FIG. 7 are denoted by the same signals, and description thereof will be omitted.

 The area within the dashed-dotted line in the figure is according to the present invention.

A follow-up width setting value P ₅ DOO governor control signal P ₃ are added by the adder 12 becomes a signal P _9. This signal P ₉ is input to the signal change rate limiter 13.

The signal rate-of-change limiter 13 is used to increase the signal,
It limits only the rate of change of the CV opening direction, and the setting is CV
The opening rate is set to a change rate (opening speed) of the valve opening required from the main body or a change rate of the steam flow rate required from the control of the steam generator. Then, only a signal faster than the set change rate is limited, and when the input signal has a change rate lower than the set change rate, the input signal is passed as it is. Further, in the signal decreasing direction, the operation is performed so that the input signal is passed as it is without limiting the change rate.

The output signal P _{10 of the} signal change rate limiter 13 and the load limit set value P
₁ and the speed control signal P ₃ are input to the low value selector 14,
The lowest signal among these three signals is selected and output. The output signal P ₈ is used to signal to adjust the CV opening as CV opening command signal.

FIG. 2 shows a signal change of each part in the embodiment shown in FIG. During time t ₄ from time t ₀ indicates a state turbine speed S ₂ is the reference value constant. During this time, the governor setting value P ₂ Doo governor control signal P ₃ following the change in the load limit setting value P ₁
Bets is following in the setting range of the follow-up width setting value P ₅ as a bias value.

Further, the follow minute by a high value output signal P ₁₀ is obtained by adding the tracking width setting value P ₅ to the governor control signal P ₃ of the signal change rate limiter 13. And since the CV opening command signal P ₈ load limit setting value P ₁ has the lowest value, this signal is output.

Next, when the turbine speed S ₂ increases rapidly at time t _5, the speed control signal S ₄ decreases rapidly. Thus the governor control signal P ₃ is rapidly decreased, CV opening degree command signal P ₈ as, governor control signal is output CV is controlled in the closing direction.

Also, at this time, the output signal P ₁₀ of the signal change rate limiter 13
Is the tracking width set value P ₅ (bias value) rather than the speed control signal P ₃
We are following at a higher value.

When the turbine speed S ₂ is the returned rapidly to the reference value at time t _8, the governor control signal P ₃ is quickly opened to the value of the governor setting value P _2.

However, the output signal P ₁₀ of the signal change rate limiter 13 changes the increasing direction in a limited rate of change. As a result, although the surge by the value of the follow-up width setting value P ₅ when the CV opening command signal P ₈ at time t _8, then changes at a constant change rate.

Then, next time t _9, the later, the output signal P ₁₀ of the signal change rate limiter 13 is higher than the load limit setting value P _1, CV opening degree command signal P ₈ is a constant load limit setting Become. And a constant output signal P ₁₀ only follow width setting value P ₅ minutes than the governor control signal P ₃ high values of the signal change rate limiter 13 at time t ₁₀ and subsequent.

As described above, even if the speed control signal suddenly increases, the CV opening command signal rapidly opens only for the bias value corresponding to the follow-up width setting value, but thereafter changes at a constant rate of change, and the CV increases. Can be fed quickly. Also, when the load limit set value changes while the turbine speed is increasing, the governor set value also changes, so that the CV opening command signal can be changed, and the added signal change rate limiter 13 It does not hinder the setting change of the load limit setting value.

Next, FIG. 3 shows another embodiment. FIG. 4 is an explanatory diagram of the operation of the embodiment. Also in the case of this embodiment, the area within the one-dot chain line in the drawing is according to the present invention.

That is, the adder 15 and the tracking width setting value P ₅ and CV opening command signal P _8, and enter the output P ₁₁ to the signal change rate limiter 13, limit the rate of change of the direction of increasing the signal Output signal
Get the P _12. Then, the CV opening command signal P is sent to the low value selector 16.
Enter the ₈ and the signal change rate limit signal P _12, the output signal P ₁₃ which selects the two lower signal ones of is output as CV opening command signal.

The difference from the embodiment shown in FIG.
Whereas had to follow a higher value only follow width setting value P ₅ minutes than the signal change rate limiter 13 output signal is governor control signal P ₃ in the case of FIG., The embodiment of the Figure 3 If an output signal is governor control signal P ₃ of the signal change rate limiter 13 load limit setting
Than lower signal ones of P ₁ is a point that follows the high value only follow width setting value P ₅ minutes.

As described above, there is a difference in following the signal change rate limit in the steady state, but this does not affect the CV opening control,
Further, there is no difference in the control for preventing the sudden opening of the CV opening command signal when the turbine speed suddenly changes, and it has completely the same function.

Next, FIGS. 5 and 6 show still another embodiment, and the embodiment of FIG. 5 corresponds to the embodiment of FIG. 1. In the embodiment of FIG. It is those in which a sum of the follow-up width setting value P ₅ on the output side of the signal change rate limiter 13, is quite have the same function in the rapid opening prevention of CV opening command signal.

The embodiment of FIG. 6 is intended for example of FIG. 3, are those provided with a sum of the follow-up width setting value P ₅ on the output side of the signal change rate limiter, rapid opening of the CV opening command signal It has exactly the same function for prevention.

Here, in any of the embodiments described above, the tracking width setting signal, which is a bias value to be added on the input side or the output side of the signal change rate limiter 13, is set to the automatic tracking setting signal of the governor setting unit 2. Although expressed by sharing, this setting has the same function even if it is not shared but individual setting.

Also, in any of the embodiments, the governor setting device has been described for automatic follow-up.However, the change rate of the CV opening in the governor setting operation state in which the governor setting value is set lower than the load limit setting value and the turbine operation is performed. It has the same function as the restriction.

[Effects of the Invention] As described above, according to the present invention, when a situation where the CV opening rapidly opens occurs, the change rate permitted from the turbine body side or the control based on the control of the steam generation source is permitted. Since the rate of change of the CV opening can be limited within a range that does not exceed the rate of change, the thermal fatigue of the turbine and the valve can be prevented and the control of the steam generation source can be stably maintained.

Needless to say, the rate of change of the CV opening is effective in both the governor setting operation and the load limit setting operation.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing an embodiment of the present invention.
FIG. 3 is an operation explanatory view showing the operation, FIG. 3 is a control block diagram showing another embodiment of the present invention, FIG. 4 is an operation explanatory view showing the operation, FIG. 5 and FIG. FIG. 7 is a control block diagram showing another embodiment, FIG. 7 is a control block diagram of a conventional example, and FIG. 8 is an operation explanatory diagram thereof. 1 ... Load limit setting device, 2 ... Governor setting device, 3,5,7,1
0,12,15 ... Adder, 4,14,16 ... Low value selector, 6 ... Following width setting device, 8 ... Signal limiter, 9 ... Reference speed setting device, 11 ... Speed control Coefficient unit, 13 ... Signal change rate limiter.

Claims (4)

(57) [Claims] 1. A speed control signal obtained by adding a speed control signal of a steam turbine to a governor setting signal from a governor setting device for setting a steam turbine output reference value, and a load limiter for setting a steam turbine output upper limit value. The load control signal from the load limiter is applied to the low value selector, and the lower signal is selected and used as the operation signal for the steam control valve. An adder for adding a follow-up width setting signal for setting a difference with the load limit setting signal to the speed control signal, and a change rate limiter for limiting a change rate of an addition signal from the adder are provided. By adding the rate-of-change limiting signal from the rate-of-change limiting device to the low value selector, the lowest signal among the three signals of the load limit set value, the speed control signal, and the rate-of-change limiting signal is selected. The steam A turbine control device, wherein the control signal is an operation signal of a depressurizing valve. 2. A speed control signal obtained by adding a speed control signal of a steam turbine to a governor setting signal from a governor setting device for setting a steam turbine output reference value, and a load limiter for setting a steam turbine output upper limit value. A load limit setting signal from the controller to a low value selector, and select a lower signal as an operation signal of a steam control valve, wherein a rate of change limiting the rate of change of the governing control signal. Vessels,
An adder for adding a tracking width setting signal for setting a difference between a governor setting signal from the governor setting device and a load limiting setting signal from the load limiting device to an output signal from the change rate limiting device; By adding the addition signal from the adder to the low value selector, the lowest signal among the three signals of the load limit set value, the speed control signal, and the addition signal is selected, and the operation signal of the steam control valve is selected. A turbine control device characterized by the following. 3. A speed control signal obtained by adding a speed control signal of a steam turbine to a governor setting signal from a governor setting device for setting a steam turbine output reference value, and a load limiter for setting a steam turbine output upper limit value. The load control signal from the load limiter is applied to the low value selector, and the lower signal is selected and used as the operation signal for the steam control valve. An adder for adding a follow-up width setting signal for setting a difference with the load limit setting signal to an output signal of the low value selector;
A rate-of-change limiter for limiting the rate of change of the addition signal from the adder; and an output signal of the rate-of-change limiter and an output signal of the low value selector, and a low signal is selected from both. And a second low value selector for outputting the output of the steam control valve, wherein an output signal of the second low value selector is used as an operation signal of the steam control valve. 4. A speed control signal obtained by adding a speed control signal of a steam turbine to a governor setting signal from a governor setting device for setting a steam turbine output reference value, and a load limiter for setting a steam turbine output upper limit value. A load limit setting signal from the controller to a low value selector, and selecting a lower signal to be an operation signal of a steam control valve, wherein a rate of change of an output signal of the low value selector is limited. A change rate limiter, and an addition for adding a follow-up width setting signal for setting a difference between a governor setting signal from the governor setter and a load limit setting signal from the load limiter to an output from the change rate limiter. And a second low value selector that inputs the addition signal from the adder and the output signal from the low value selector, selects and outputs the lower signal of the two, The output of this second low value selector A turbine control device, wherein a signal is an operation signal of the steam control valve.