JPH02221604A - Method and device for controlling power plant and power plant - Google Patents

Abstract

PURPOSE:To effectively prevent a steam turbine in any case from being excessively accelerated by suddenly closing a control valve for the speed of the turbine when the speed detection value of the steam turbine rises to above a speed definition value preset as a load function. CONSTITUTION:In order to control a power plant, it is detected 30 first whether or not the load during operation of the power plant is more than the x% of all the loads. Next, it is defecated 31 whether or not the detection value of the turbine speed is more than a definition value preset as a load function. When all the results of diagnosis are affirmative, then a control valve sudden closing command 19 is outputted to a sudden closing solenoid valve 17 so as to cut off steam supply to the turbine. The turbine speed is thus set as a direct condition for suddenly closing the control valve, so that the excessive acceleration of the steam turbine is prevented effectively and in any case regardless of operational conditions of the steam turbine.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power generation plant, and in particular to a power generation plant control method and device suitable for preventing overspeed of a steam turbine that occurs during load shedding, and this device. The present invention relates to a power generation plant comprising:

[Conventional technology]

FIG. 8 is a configuration diagram of a cross compound power generation plant. This power generation plant includes a boiler (not shown) in which a high-pressure turbine 1 and an intermediate-pressure turbine 2 rotate a shaft 3 to drive a generator 4, and low-pressure turbines 5 and 6 rotate a shaft 7 to drive a generator 8. The steam supplied through the main steam stop valve 9 from the steam control valve (high pressure turbine control valve) 10
The flow rate is controlled and enters the high pressure turbine 1 to do work.

Steam flowing out of the high-pressure turbine 1 is reheated by a reheater 11, enters the intermediate-pressure turbine 2 via a reheat steam stop valve 12, an intercept valve (control valve for intermediate-pressure turbine) 13, and performs work. Steam and gas flowing out from the intermediate pressure turbine 2 pass through the crossover pipe 14 and enter the low pressure turbines 5 and 6.
After doing its work, it enters a condenser (not shown) and is condensed.

The control device 15 detects the rotational speed of the shaft 3 or shaft 7 (both shafts are synchronized) with a speed detector (not shown), and adjusts each control valve 10.13 according to this detected value.
It functions to control the opening of the turbine and the speed of the turbine.

FIG. 7 is a control function diagram of the control valves 11, 13 (hereinafter simply referred to as control valves) described above. The control valve includes a servo valve 16 that can finely adjust its opening degree, and a quick-closing solenoid valve 17 that controls the opening degree on and off. Control device 1
5 (Fig. 8), when the control valve opening command 18 is output to the servo valve 16, the servo valve 16 is controlled according to the command, the steam flow supplied to the turbine is adjusted, and the turbine speed is controlled. be done. When the load is cut off and the turbine speed increases to an overspeed state, the control device 15 outputs a control valve quick-closing command 19 to the quick-closing solenoid valve 17, and the action of the solenoid valve 17 causes the hydraulic cylinder of the control valve to quickly shut off. The control oil is discharged and the control valve closes suddenly, cutting off the steam supply to the turbine.

FIG. 10 is a block diagram showing a conventional control valve quick closing procedure executed by the control device 15.

A speed regulation signal corresponding to the rated speed of the turbine is output from the signal generator 20, and a speed detection signal corresponding to the actual speed of the turbine is output from the speed detector 21. The adjustment rate calculator 22 creates a load signal according to the deviation between the two speed signals, and this load signal is sent to the load setting controller 23 or the governor setting device 23.
The control valve opening command is created by the valve opening setting device 24. The valve opening degree detector 25 detects the actual valve opening degree, the deviation between this valve opening degree detection value and the valve opening degree command is taken, and the comparator 26 compares this deviation with a specified value, If the deviation is greater than or equal to the specified value, a control valve quick-closing command 19 is output to the quick-closing solenoid valve 17.

In addition, as related to the prior art,
There is number 927.

[Problem to be solved by the invention]

The above conventional technology is effective in a constant pressure steam turbine power plant (hereinafter referred to as a low pressure plant). but,
When applied to a variable pressure steam turbine power plant (hereinafter referred to as a variable pressure plant), the problem is that the valve opening becomes large when a load cutoff occurs at one partial load, and the turbine speed becomes overspeed. There is. This problem will be explained with reference to FIG.

FIG. 9(a) is a graph showing the relationship between turbine speed and load setting in a constant pressure plant. In a constant pressure plant, the main steam pressure is always constant regardless of the load, so there is a proportional relationship between the control valve opening setting (load setting) and the load.

Therefore, the position of the load setting at partial load is low as shown in this figure, and even if the turbine speed increases during load cutoff, the valve opening setting of the intercept valve decreases at low speed (point a in this figure). A quick valve opening according to the prior art is performed.

FIG. 9(b) is a graph showing the relationship between turbine speed and load setting in a transformer plant. In variable pressure plants, the main steam pressure is low at partial load.

For this reason, the control valve opening control valve becomes larger compared to a constant pressure plant. Therefore, the opening degree setting of the intercept valve cannot be lowered unless the speed reaches a high speed (point b in the figure), which inevitably causes a large increase in the turbine speed during load cutoff or the like.

A first object of the present invention is to provide a power plant control method for overspeed prevention that can also be applied to a voltage transformer plant.

A second object of the present invention is to provide a power plant control device for overspeed prevention that can also be applied to a voltage transformer plant.

A third object of the present invention is to provide a power generation plant that prevents overspeeding.

[Means to solve the problem]

Above 1. The second purpose is to set the overspeed specified value according to the load, and then quickly close the control valve when the actual detected speed value exceeds the speed set value corresponding to the load at that time. achieved.

The third objective is achieved by providing the power plant with a power plant control device that achieves the second objective.

[For production]

The speed regulation value that determines whether or not to close the control valve quickly is set according to the load, so when the load is small, such as during partial load, the control valve is quickly closed at a lower speed, which reduces the turbine speed. Overspeeding under partial load, etc. is prevented.

In addition, when the control valve is to be suddenly closed, the sudden closing signal may be sent directly to the control valve, or the deviation specified value used to determine whether or not to close suddenly may be changed, or the deviation specified value may be changed. It may be possible to close quickly by increasing the deviation to be compared.

Furthermore, by equipping a plant with the control device of the present invention,
Turbine overspeed can be prevented in all power plants, regardless of the type of power plant, constant pressure plant or variable pressure plant, -shaft type or cross compound type.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to No. 1 to No. 6. Note that parts that overlap with those described in FIG. 10 are designated by the same reference numerals, and the description thereof will be omitted. Further, although this embodiment will be described as an example applied to the power generation plant shown in FIG. 8, it goes without saying that the present invention can be applied to other types of power generation plants as described above.

FIG. 1 is a block diagram showing a control procedure for implementing a control method according to a first embodiment of the present invention.

In this embodiment, first, it is determined whether the load during operation is X% or more of the full load (30). This value is stored in advance in a storage means (not shown) of the control device, such that it can be determined that even if the control valve quick-closing control is performed, the increase in turbine speed is small and that performing this control would result in useless control.

Next, the detected value of the turbine speed detected by the speed detector,
It is compared with a speed regulation value previously stored in a storage means (not shown) of the control device, and it is determined whether the detected speed value is equal to or greater than the speed regulation value (31).

As an example of the function setting of the specified speed value, at low loads, the specified speed is set slightly higher considering fluctuations in the normal state of the system, and at high loads, the specified speed is increased by combining with another control valve quick-closing mechanism. Possible methods include: For example, in this embodiment, as shown in Fig. 1, the specified speed value takes a constant value until the load reaches a certain value, and when the load exceeds that value, it takes a value that increases as the load increases. This is set in advance. The load dependence of the specified speed value differs depending on the power plant to which the present invention is applied.

Set the speed regulation value according to the type and load of the power generation plant.

According to the above two judgments 30.31, when the load is X% or more and the detected speed value is more than the specified speed value according to the load at that time, the control valve quick-closing command 19 is sent to the quick-closing solenoid valve 17. and cut off the steam supply to the turbine. As a result, even if load shedding is performed during partial load, etc.,
Since the steam supply to the turbine is cut off, overspeeding of the turbine speed is prevented. Further, when the load is extremely low (1% or less), this quick closing control is not performed, so unnecessary control is avoided.

In the embodiment described above, the speed regulation value is set according to the load. However, as a special example of setting the specified speed value according to the load, the specified speed value may be set to a constant value.A second embodiment of the present invention using this special example is shown in FIG. explain. In this embodiment, in determination 31', it is determined whether the detected speed value is equal to or greater than y% of the turbine rated speed. Then, when the load at 1 judgment 30 becomes X% or more of the total load, and when the speed detection value becomes y% or more of the rated speed at 1 judgment 31', the control valve quick-closing command 19 is activated by the quick-closing solenoid. It is sent to valve 17. In this way, even if the specified speed value to be compared with the detected speed value is a constant value, the first
There are effects similar to those of the embodiment.

In the first and second embodiments described above, the control valve quick-closing command 19 is directly sent to the quick-closing solenoid valve 17, but for example, in a power plant equipped with the control valve mechanism explained in FIG. It is possible to close the door quickly by another method without sending a quick closing command to the door.

An example of this will be explained below.

FIG. 3 is a block diagram showing the control procedure of the third embodiment of the present invention, which is a combination of the block diagram of the first embodiment and the block diagram of FIG. , when the load is more than X% of the total load and the detected speed value is more than the specified speed value according to the load, the load setting, that is, the setting value of the control valve or governor, is lowered instantaneously or in a very short period of time (this operation is In this way, the deviation between the control valve (governor) set value and the actual control valve opening value (governor value), which is compared with the deviation specified value by the comparator 26. becomes large and exceeds the standard deviation value. Therefore, the control valve quick-closing command 19 is sent to the quick-closing solenoid valve 17.

FIG. 4 is a block diagram showing a control procedure according to a fourth embodiment of the present invention, and is a combination of the block diagram according to the second embodiment in FIG. 2 and the block diagram in FIG. be. This case is also similar to the third embodiment.

In the third and fourth embodiments, the load setting was run back, but of course, rather than running back the load setting, the deviation specified value compared with the comparator was made smaller, and the deviation was It goes without saying that the same effect can be achieved even if the side thread is made smaller than the specified value.

FIG. 5 is a block diagram showing the control procedure according to the fifth embodiment of the present invention. In this embodiment, in addition to the control procedure of the third embodiment (FIG. 3), the control valve (governor) is opened. If the degree deviation is equal to or greater than a specified value, the load setting runback is performed even if the load is equal to or greater than X%. ), the speed condition (judgment 30
Under operating conditions in which the control valve opening deviation condition (control valve opening deviation > deviation specified value) is established earlier than when the detected speed value is determined to be equal to or higher than the specified speed value, the During the turbine speed stabilization process, the turbine speed is quickly reduced to near the rated speed, making plant operation easier. In other words, in this example.

Runback of load settings based on speed conditions controls both control valve quick closing control and speed stabilization control after load cutoff, and further speed stabilization is achieved by runback of load settings based on control valve opening conditions. That's what I do.

FIG. 6 is a block diagram showing a control procedure according to a sixth embodiment of the present invention. In this embodiment, in addition to the control procedure of the fourth embodiment (Fig. 4), the load setting is performed even when the control valve (governor) opening degree deviation is above the specified value and when the load is above X%. I am trying to perform a runback. This runback of load settings is performed in the same manner as in the fifth embodiment.

〔Effect of the invention〕

According to the control method and apparatus of the present invention, since the turbine speed is used as a direct control valve rapid closing condition, overspeeding of the steam turbine can be effectively prevented in any case regardless of the operating conditions of the power plant. . Therefore, in a power plant equipped with the control device of the present invention, an overspeed state can be avoided in any operating state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control procedure according to a first embodiment of the present invention, FIG. 2 is a block diagram showing a control procedure according to a second embodiment of the present invention, and FIG. 3 is a block diagram showing a control procedure according to a second embodiment of the present invention. FIG. 4 is a block diagram showing the control procedure according to the third embodiment, and FIG.
FIG. 5 is a block diagram showing the control procedure of the embodiment. FIG. 5 is a block diagram showing the control procedure according to the fifth embodiment of the present invention.
The figure is a block diagram showing a control procedure according to the sixth embodiment of the present invention, FIG. 7 is a functional configuration diagram of a control valve, FIG. 8 is a configuration diagram of a cross compound steam turbine, and FIG. 9(a),
(b) is a characteristic graph explaining the problems of the prior art, the first
FIG. 0 is a block diagram showing a control procedure in the prior art. 1...High pressure turbine, 2...Intermediate pressure turbine, 3,7
... Shaft, 4, 8 ... Generator, 5, 6 ... Low pressure turbine, 9 ... Main steam stop valve, 10 ... Steam control valve (control valve for high pressure turbine), 11.・・Reheater, 12・・
・Reheat steam stop valve, 13... Intercept valve (control valve for intermediate pressure turbine), 15... Control device, 17...
Quick closing solenoid valve, 19...Control valve quick closing command, 23...Load setting, 25...Control valve set opening degree, 26...Comparing the deviation of the control valve opening degree with the specified deviation value Comparator, 30...
・Load judgment, :H, 31'...Speed judgment, 23...
Load setting runback.

Claims (1)

[Claims] 1. In a power generation plant control method in which the steam flow supplied to a steam turbine is controlled by a control valve to control the turbine speed, the actual turbine speed is determined from a preset speed value as a function of load. 1. A power generation plant control method, characterized in that the control valve is suddenly closed when the temperature rises. 2. A method in which the steam flow supplied to the steam turbine is controlled by a control valve to control the turbine speed, and the deviation between the actual opening value and the set opening value of the control valve exceeds a specified value. In the power generation plant control method for rapidly closing the control valve when the actual turbine speed increases from a speed regulation value preset as a function of load, the deviation regulation value is reduced. power plant control method. 3. A power generation plant control method according to claim 2, characterized in that instead of reducing the prescribed value of the deviation, the deviation is made larger by running back the valve opening value of the load setting. 4. A method of controlling the turbine speed by controlling the steam flow supplied to the steam turbine using a control valve, in which the deviation between the actual opening value and the set opening value of the control valve exceeds a specified value. In a power generation plant control method in which the control valve is suddenly closed, when the actual turbine speed increases from a speed regulation value that is preset as a function of load, or when the actual opening value and the set opening of the control valve are A power generation plant control method characterized by running back a valve opening value for load setting when the deviation from the value exceeds a specified value. 5. A power generation plant control method according to any one of claims 1 to 4, characterized in that the speed regulation value set in advance as a function of load takes a constant value. 6. In a power generation plant control device that controls the steam flow supplied to the steam turbine using a control valve to control the turbine speed, a storage means that stores a specified speed value set as a function of load and a storage means that stores the actual turbine speed. A speed detection device detects the speed, reads out a speed regulation value corresponding to the current load value from the storage means, compares it with the detection value of the speed detection device, and if the detection value is larger than the speed regulation value, the control valve 1. A power generation plant control device comprising: control means for sending a sudden closing signal to a power plant. 7. A device for controlling the turbine speed by controlling the steam flow supplied to the steam turbine using a control valve, which calculates the deviation between the actual opening value and the set opening value of the control valve, and calculates the deviation and the deviation regulation. The control device is set as a function of load in a power generation plant control device that sends a sudden closing signal to the control valve to quickly close the control valve when the deviation exceeds the specified deviation value. a storage means storing a speed regulation value; a speed detection device for detecting the actual turbine speed; and a speed regulation value corresponding to the load value at that time is read from the storage means and compared with the detection value of the speed detection device. A power generation plant control device comprising: control means for reducing the specified deviation value when the detected value is larger than the specified speed value. 8. The power plant control device according to claim 7, wherein the control means increases the deviation by running back the valve opening value of the load setting instead of reducing the specified deviation value. 9. A device that controls the steam flow supplied to a steam turbine using a control valve to control the turbine speed, which calculates the deviation between the actual opening value of the control valve and the set opening value, and calculates the deviation and the specified deviation value. In a power generation plant control device that compares the deviation with a first comparison means and sends an abrupt closing signal to the control valve to suddenly close the control valve when the deviation becomes equal to or greater than the specified deviation value, as a function of the load. a storage means that stores a set speed regulation value; a speed detection device that detects the actual turbine speed;
a second comparing means reads out a specified speed value corresponding to the value of the load at that time from the storage means and compares it with the speed detected value of the speed detecting device; and control means for running back the valve opening value of the load setting when the deviation becomes larger than a specified value or when the deviation becomes equal to or greater than the deviation specified value according to the first comparison means. Power generation plant control equipment. 10. The power generation plant control device according to any one of claims 6 to 9, wherein the specified speed value set according to the load takes a constant value. 11. A steam turbine, a generator driven by the steam turbine, a control valve that controls the steam flow supplied to the steam turbine and controls the turbine speed, and a control signal is sent to the control valve. A power generation plant comprising the power generation plant control device according to claim 10.