JP3063298B2 - Steam turbine valve controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve for controlling the flow, cutoff or flow rate of steam flowing into a turbine, for example, a valve such as a main steam stop valve, a steam control valve, a reheat steam stop valve, an intercept valve and the like. It relates to a control device.

[0002]

2. Description of the Related Art A steam turbine has a steam valve such as a steam stop valve for controlling the flow of steam flowing into the turbine and a shutoff valve for controlling a flow rate of steam . For example, in the reheat turbine shown in FIG. 9, a main steam stop valve 13 and a steam control valve 14 are provided at a location where the main steam from the boiler 10 flows into the high-pressure turbine 15 via the pipeline 1. The exhaust gas flows into the reheater 11 of the boiler 10 via the pipe 2 having the check valve 16, and reheats to a location where the reheated steam from the reheater 11 flows into the medium pressure turbine 19 via the pipe 3. A steam stop valve 17 and an intercept valve 18 are provided to control the flow, cutoff, and flow of main steam and reheat steam. A high-pressure bypass valve 1 is connected to a high-pressure bypass pipe 4 for bypassing the high-pressure turbine 15.
A low-pressure bypass stop valve 23 and a low-pressure bypass control valve 24 are provided in the line 5 that allows the reheat steam to flow from the line 3 into the condenser 22 by bypassing the medium-pressure turbine 19 and the low-pressure turbine 20. When the turbine is started or stopped or when the load suddenly drops, these valves are opened to increase the steam pressure to medium or high pressure.
The low-pressure turbine is bypassed and flows into the condenser 22. In addition, 21 is a generator.

[0003] The above-described steam stop valve, steam control valve, a steam valve, such as the bypass valve is activated the steam turbine, requires that the smooth control of the opening and closing valve opening degree of the valve is performed in response to stop and the output control is there. As a device having such a function, a valve control device having a control system such as a main steam control valve shown in the system diagram of FIG. 10 is conventionally known. These devices have been filed by the present applicant and are disclosed in Japanese Patent Application Laid-Open No. 63-223307.
It is publicly known from Japanese Patent Publication No. FIG. 11 is a sectional view of the main servo pressure distribution valve for the valve control device of FIG. 10 and 11, the main servo pressure distribution valve 37 has a spool 37b provided with a spring 37a.
The end protruding from 7 is pin-connected to a pin 70 of a lever 69 of the low value selection mechanism 36. The main servo pressure distribution valve 3
7 is supplied with pressure oil via a line 42, and this pressure oil is supplied to an output port 37c and an input port 3 of the hydraulic servo cylinder 38.
Hydraulic servo cylinder 38 via line 72 connected to 8c
Supplied to Land part (large diameter part) of spool 37b
Width as shown in FIG. 1 1 forms an output port 37c equal cylindrical shape. Therefore, the characteristic of the opening area of the port in the valve opening direction and the valve closing direction with respect to the displacement of the spool of the conventional main servo pressure distribution valve is linear.

[0004]

The most important functions required of the control device are responsiveness and stability, but the two are often in conflict. For example,
If the time constant of the valve control device is reduced, the responsiveness of the entire control device is improved, but the stability tends to deteriorate. Conversely, if the time constant is increased, the tendency of the entire control device is reversed. Because conventional valve controllers have a single time constant, either responsiveness or stability may be inadequate, or another device may be provided to compensate for the inadequate function .
There is a problem that must be added . Various countermeasures have been taken as a countermeasure for transient stability in order to enable stable synchronous operation even for system fluctuations. One of the technologies that can be expected to be effective as a thermal power plant is high-speed valve control. The direct cause of system instability is that during a so-called system failure, the imbalance between the mechanical output and the electrical output of the turbine causes acceleration and increases the internal phase difference angle, leading to step-out. A means for reducing the acceleration energy is high-speed valve control. For example, when trying to perform high-speed valve control that is considered to be useful for improving transient stability when a failure occurs in the power system,
It is preferable that the operation speed is high not only in the closing direction but also in the opening direction.However, when the operation speed is high, there is a possibility that the stability may be reduced, and in a conventional valve control device having a single time constant, In such a situation, it is difficult to obtain a response that satisfies the user sufficiently.

An object of the invention is, in the normal operation of the steam turbine has a stability, in such system fault or high speed valve control is to provide a valve control apparatus having a readiness.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems
According to the present invention , an electric valve is connected to a piston shaft of a hydraulic servo cylinder to control an opening degree of a steam valve for performing flow, cutoff or flow rate control of steam flowing into a turbine, or to close the steam valve. A hydraulic servo valve and a solenoid valve, or an auxiliary servo to which the output oil amount from each of a plurality of solenoid valves is respectively input, and the auxiliary servo operates by preferentially receiving the smaller displacement of the spool displacement, In a steam turbine control device provided with a low value selection mechanism for supplying pressure oil to a servo cylinder and operating a spool of a main servo pressure distribution valve , a spout for opening and closing an output port of the main servo pressure distribution valve is provided.
Over the width of the output port on both sides of the land part of the
An axially extending skirt is provided and this skirt has its ends
By forming a notch from the surface, the spool
The characteristic of the opening area of the output port corresponding to the displacement is
The gain is large when the spool displacement is small.
Non-linearity that is smaller than the gain in the range
(Claim 1).

[0007] The range of the main servo distribution valve is to reduce the gain corresponding to the displacement of the spool is small in the closing direction of the steam valve, by increasing in the opening direction, to correspond to a sudden load change The above is preferable (claim 2).

[0008] In addition, preferably on by setting the three levels to gain the displacement of the spool in the opening direction of the steam valve to control finely the valve opening degree corresponding to the load change with respect to the spool displacement of the main servo distribution valve (Claim 3) .

[0009]

A first auxiliary servo for guiding the amount of oil output from the electrohydraulic servo valve and a second auxiliary servo for guiding the amount of oil output from the solenoid valve are provided. The spool of the first auxiliary servo and the second auxiliary servo are provided. The servo spool preferentially receives a small displacement among the displacements caused by the respective oil amounts, and activates a low value selection mechanism which is a mechanical low value selection gate. That is, when the displacement of the spool of the second auxiliary servo is made larger than the displacement of the spool of the first auxiliary servo, the low value selection mechanism receives the displacement of the spool of the first auxiliary servo and gives priority to the main servo pressure distribution valve. The spool is moved to supply the output oil amount from the electro-hydraulic servo valve to the hydraulic servo cylinder from the pressure distribution valve to move the piston shaft, thereby opening and closing the steam valve connected to the piston shaft. The main servo distribution valve is the strange
The port opening area characteristic with respect to the position is non-linear, and the gain is small in a range where the displacement is small, such as in a balanced operation state, and is large in a range where the displacement is large, such as when the state changes suddenly. Due to such nonlinear characteristics,
While it is possible to respond to a state change at a high speed, it is possible to shorten the convergence time before returning to a stable state, and to obtain sufficient stability in an equilibrium state. The operation of the main servo pressure distribution valve through the low ground low value selection mechanism via the auxiliary servo using the plurality of solenoid valves and the output oil amount from the solenoid valves is based on the operation of closing the steam valve. In order to increase the reliability in order to increase the reliability, the displacement of the spool of the auxiliary servo connected to each solenoid valve due to the interruption of the amount of hydraulic oil due to the closing operation of the solenoid valve gives priority to operating the low value selection mechanism. Thereby, the spool of the main servo pressure distribution valve is moved to supply the hydraulic oil amount from the pressure distribution valve to the hydraulic servo cylinder, and the steam valve connected to the piston shaft is closed.

[0010]

The EXAMPLE 1 5 is a system diagram of a valve control device for a steam turbine used in the first embodiment of the present invention. In FIG. 5, the system configuration of the valve control device is the same as that of FIG. 10 except for the pressure distribution valve spool 37b, so that the description is omitted. FIG. 1 is a sectional view of a main servo pressure distribution valve used in a valve control device according to a first embodiment of the present invention. 1, the same parts as those in FIG. 11 are denoted by the same reference numerals. In Figure 1, the spool 37b of the main distribution valve
Are output ports 3 on both sides of the land (large diameter).
Provided a skirt 37d extending in the axial direction beyond the width of 7c, 37e notched from the end face on the skirt 37d
Was formed. As a result, the main servo pressure distribution valve 37 changes the opening area of the output port 37c with respect to the displacement of the spool 37b .
Increase small bloom in the range displacement of the spool 37b is small,
Displacement of the spool 37b is non-linear characteristic such that greatly resulting in a large range.

FIG. 2 shows a spool change of the main servo pressure distribution valve of FIG.
FIG. 5 is a diagram illustrating characteristics of a position-opening area of an output port. Figure
3 shows a small displacement δ of the spool of the main servo pressure distribution valve of FIG.
FIG. 4 is a sectional view showing the state, and FIG.
FIG. 4 is a cross-sectional view showing a state in which the displacement δ of the tool is large. In FIG.
In the part III, the spool 37b of the main pressure distribution valve is the same as in FIG.
And the displacement of the spool is δoutputport37c
Indicates that the opening area A of the main pressure regulating valve is small.
Is located at the position shown in FIG.
Is δoutputport37cIndicates that the opening area A is large.
are doing. XI is the spool 37 of the conventional main pressure distribution valve.
b, corresponding to the displacement δ of the spooloutputport3
7cShows the characteristics of the opening area A. Non-linear characteristics are main pressure regulating valve
Not on the spool but on the cylinder side
Is theoretically possible, but practical because machining is difficult
Not a target. Skirt 37d and notch 37eAxis direction
LengthIn the closing direction of the steam valveShortIn the opening direction
Inlongdid.This allowsGain of main pressure regulator 37
The range for reducingsteamIn the closing direction of the valvesmall
In the opening direction.

In the device used for power generation, the skirt 3
7d axial length (corresponding to displacement direction of spool 37b)
Is preferably relatively short in the direction in which the control valve acts in the closing direction and relatively long in the direction in which it is used in the opening direction. The reason is that in the case of power generation, when the load of the generator is interrupted, etc., the control valve must perform an operation to fully close quickly, whereas in the opening direction of the control valve, generally such a high speed operation is not possible. It is not required. As values usually selected, the ratio of the axial length of the skirt 37d to the spool diameter is about 0.01 to 0.025 in the direction in which the control valve acts in the closing direction, and 0.05 or more in the direction in which the regulating valve acts in the opening direction. Not particularly provided. However, when there is a possibility that high-speed valve control may be performed, a certain high-speed operation is required even in the opening direction of the control valve. Therefore, the upper limit of the ratio of the axial length of the skirt / spool diameter in the opening direction is set to 0.05.
It is better to be about 0.1.

FIG. 6 is a block diagram of the valve control device according to the first embodiment. In FIG. 5, a deviation between a valve opening target value according to the turbine output and a detected opening from the opening transmitter 33 is detected and amplified, and an electric signal based on the deviation is converted into an opening controller 3.
0 is input to the electro-hydraulic servo 31. This electric signal is converted into an output oil amount of the pressure oil by the electro-hydraulic servo valve 31, and is supplied from the guide valve 31 a to the auxiliary surf 32 via the pipe line 60 or 61. At this time, for example, the guide valve 31a
When the spool moves to the right, the pressure oil is supplied to the auxiliary servo 32 via the line 60, while the pressure oil is discharged via the line 61, and the spool 32a of the auxiliary servo 32 moves to the right. The spool 32a rotates the T-shaped lever 63 of the low value selection mechanism 36 around the pin 65 via the U-shaped lever receiver 32b and the lever 64 to tilt rightward. At this time, the displacement of the spool 32a is fed back to the opening adjuster 30 by the opening transmitter 33 and compared with the target opening value. When the deviation disappears, the spool of the guide valve 31a returns to the neutral position. Therefore, the spool 3 of the auxiliary servo 32
The position 2a stops at a position corresponding to the opening target value. The low value selection mechanism 36 is moved by the displacement of the spool 32a thus displaced, and the T-shaped lever 63, the lever 67,
The spool 37b of the main servo pressure distribution valve 37 is displaced via 69. The spool 37b of the main servo pressure distribution valve 37 is shown in FIG.
It operates non-linearly as shown in (1). The above spool 37b
Rightward displacement of the spool 3 via the low value selection mechanism 36
7b is moved to the left, the pressure oil in the main servo cylinder 38 is drained from the oil drain pipe 48 through the pipe line 72, and the piston shaft 38a of the hydraulic servo cylinder 38 is moved leftward by the force of the spring 38b. The steam valve, for example, the steam control valve is moved in the opening direction. The displacement of the piston shaft 38a is fed back to the spool 37b of the main servo pressure distribution valve 37 via the lever 69 of the low value selection mechanism 36 by the cam mechanism 39, and the spool 37b is in the neutral position.
8a is held at an opening corresponding to the valve opening target value.

[0014] Incidentally, the degree of opening of the steam valve has been described opening direction, the closing direction are obtained if the flow of displacement and the pressure oil in each spool in the opposite direction, opening of conventional steam valve in this manner Degree control is performed. A fully open signal is input to the solenoid valves 34 and 64 both during normal steam turbine operation, and pressure oil is supplied to the auxiliary servo 35 to push the spool 35b again to the left end against the spring 35a. When it is desired to cut off the flow rate of steam in an emergency of a steam turbine or the like, the supply of the pressure oil to the auxiliary servo 35 is cut off by closing the solenoid valves 34 and 64 or one of them. Therefore, the pressure oil in the auxiliary servo 35 is discharged as described above, and the spool 35b of the auxiliary servo 35 moves rightward by the force of the spring 35a. This displacement is applied to the spool 32 of the auxiliary servo 32.
Since the displacement is larger than the displacement a, the spool 35b quickly pushes the T-shaped lever 63 rightward over the gap 35d provided in advance between the lever receiver 35c and the lever 65 of the low value selection mechanism 36. Therefore, the steam valve can be quickly closed by the action of the hydraulic servomotors such as the main servo pressure distribution valve 37 and the hydraulic servo cylinder 38 described above.

Embodiment 2 FIG. 7 is a sectional view of a main servo pressure distribution valve used in a valve control device according to a second embodiment of the present invention. 7, the same parts as those in FIG. 1 are denoted by the same reference numerals. In the example of FIG. 7, the main servo pressure distribution valve 37 is provided with a notch 37 provided on a skirt 37d that acts when the spool 37b is displaced in the control valve opening direction.
The e shape, leaving a small range of displacement of the spool 37b
As the opening area of the force port 37c is very small and in the range displacement is greater than this it was so that apertures area becomes relatively large.

FIG. 8 is a graph showing the characteristics of the displacement of the spool 37b and the opening area of the output port of the main servo pressure distribution valve 37 of FIG. In FIG. 8, VII indicates the characteristic of the second embodiment, I indicates the characteristic of the first embodiment, and XI indicates the characteristic of the conventional pressure distribution valve. VII has properties intermediate between I and XI. By changing the shape of the notch 37e, finer characteristics can be obtained. It is an advantage of this method that fine characteristics can be given according to the purpose of use.

[0017]

According to the present invention, the main servo pressure distribution valve is
By making the characteristics of the opening area of the port corresponding to the displacement of the spool non-linear and reducing the gain in a small range of the displacement of the spool, the stability of control can be improved in a balanced operating state. When the load is interrupted or when a state change must be quickly responded such as in high-speed valve control, the change can be quickly responded to the fully closed direction of the steam valve and, if necessary, also to the open direction. In this way, the control device can satisfy two conflicting requirements: stability and responsiveness.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main servo pressure distribution valve used in a valve control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing characteristics of a displacement of a spool and an opening area of an output port of the main servo pressure distribution valve of FIG. 1;

FIG. 3 is a sectional view showing a state where the displacement of a spool of the main servo pressure distribution valve of FIG. 1 is small.

FIG. 4 is a cross-sectional view showing a state where the displacement of a spool of the main servo pressure distribution valve of FIG. 1 is large.

FIG. 5 is a system diagram of a control device according to the first embodiment of the present invention.

FIG. 6 is a block diagram of the valve control device of FIG. 5;

FIG. 7 is a sectional view of a main servo pressure distribution valve used in a valve control device according to a second embodiment of the present invention.

FIG. 8 is a diagram showing characteristics of the displacement of the spool of the main servo pressure distribution valve of FIG. 7 versus the opening area of the output port.

FIG. 9 is a system diagram of a reheat turbine.

FIG. 10 is a system diagram of a conventional steam turbine valve control device.

FIG. 11 is a sectional view of a conventional main servo pressure distribution valve.

[Explanation of symbols]

 14 Valve 31 Electro-hydraulic servo valve 32 Auxiliary servo 34 Solenoid valve 35 Auxiliary servo 36 Low value selection mechanism 37 Main servo pressure distribution valve 37b Spool of main servo pressure distribution valve 37c Output port 37d Skirt 37e Notch 38 Hydraulic servo cylinder 38a Piston shaft

Claims (3)

(57) [Claims] 1. An electrohydraulic device connected to a piston shaft of a hydraulic servo cylinder for controlling an opening of a steam valve for performing flow, cutoff or flow control of steam flowing into a turbine, or for closing the steam valve. An auxiliary servo to which the output oil amount from each of the servo valve and the solenoid valve or the plurality of solenoid valves is inputted, and a small displacement among the displacements of the spool of the auxiliary servo are preferentially received and operated. A control unit for a steam turbine provided with a low value selection mechanism for supplying pressure oil to a cylinder and operating a spool of a main servo pressure distribution valve ;
Over the width of the output port on both sides of the land
Skirt that extends in the direction
By forming a notch from the
The characteristics of the opening area of the output port corresponding to the
The gain in the small displacement range of the pool is
A valve control device for a steam turbine, wherein the valve control device is non-linear so as to be smaller than a gain in a surrounding area . 2. The steam turbine valve control device according to claim 1, wherein the range in which the gain corresponding to the displacement of the spool is reduced in the closing direction of the steam valve.
A valve control device for a steam turbine, characterized in that it is enlarged in the opening direction. 3. The valve control apparatus for a steam turbine according to claim 1, wherein said steam valve is opened with respect to displacement of said spool.
A valve control device for a steam turbine, wherein a directional gain is set in three stages .