Water turbine governor main distributing valve element operation refusing detection device and water turbine governor main distributing valve element operation refusing detection method

Abstract

The invention discloses a water turbine governor main distributing valve element movement refusing detection device and method, the detection device comprises a valve element displacement linkage rod, a screw rod and a position switch, the valve element displacement linkage rod is connected to the end of a main distributing valve element and can synchronously move along with the main distributing valve element; the screw rod is connected with the valve core displacement linkage rod through a connecting block; the screw is sleeved with a spring, and nuts are arranged at the positions, located at the two ends of the spring, of the screw and used for axially limiting the spring. The position switch is a travel touch switch and is fixedly arranged on the upper side of the spring; when a small touch ball of the travel touch switch is located at the concave position of the spring, the small touch ball stretches, and the travel touch switch reports a 0 signal; when the spring collides with the small touch ball, the small touch ball is compressed, and the travel touch switch reports a signal of '1'; in the whole stroke of the movement of the valve core of the main distributing valve, the stroke touch switch can report at least two periods of '0, 1' signals. According to the invention, the valve core operation rejection signal can be accurately and reliably identified.

Description

Technical Field

[0001] The invention relates to fault identification of a turbine governor, and in particular to a device and method for detecting valve core refusal to move of a main pressure regulating valve of a turbine governor. Background Art

[0002] The turbine speed governor is one of the core control devices of the hydropower station, and the main pressure regulating valve is the core control device of the turbine speed governor. The main pressure regulating valve directly controls the opening and closing of the guide vanes, and its normal operation is related to the safety of the unit. However, during the operation of the equipment, it is inevitable that the main pressure regulating valve core will not move due to jamming or abnormal control (referred to as main pressure regulating valve refusal to move).

[0003] On the other hand, hydropower stations are generally equipped with a three-level overspeed shutdown mechanism to protect the units, namely level one overspeed, level two overspeed, and level three overspeed shutdown.

[0004] Principle of first-stage overspeed shutdown:

[0005] like Figure 1 As shown in the figure, when the unit speed is greater than 115% of the rated speed, the guide vane opening is greater than the no-load opening, and the turbine governor main pressure regulating valve refusal signal is received, the computer monitoring system outputs an emergency shutdown order after a delay of several seconds. The emergency shutdown order drives the emergency pressure regulating valve, and the emergency pressure regulating valve independently actuates the guide vane servomotor, closes the guide vane, and shuts down.

[0006] Secondary overspeed shutdown principle:

[0007] If the unit speed continues to rise to 140% (the value is different for each power plant, this is an example) after the first stage overspeed fails, the computer monitoring system will directly output a shutdown signal to the emergency pressure regulating valve, and the emergency pressure regulating valve will independently actuate the guide vane servo to close the guide vane and shut down the unit.

[0008] Three-level overspeed shutdown principle:

[0009] If the unit speed continues to rise to 145% (the value is different for each power plant, this is an example) after the secondary overspeed fails, the mechanical overspeed device changes the oil pressure signal to the emergency pressure regulating valve through the mechanical reversing valve. The emergency pressure regulating valve independently activates the guide vane relay to close the guide vane and shut down the unit.

[0010] In the overspeed shutdown mechanism, if the main pressure distribution valve does not move, cannot be detected normally, and cannot alarm, it will cause great harm to the unit. For example, when the unit is unloaded and the speed rises, if the main pressure distribution valve refuses to move, if it can normally alarm the computer monitoring system, the speed of the unit is at the first-level overspeed setting speed, and the computer monitoring system will send an emergency shutdown signal to the accident pressure distribution valve to shut down the unit. If the main distribution valve refuses to move, but it is not normally reported to the computer monitoring system, the speed of the unit will continue to rise and rise to the second-level overspeed setting speed, endangering the safety of the unit. Therefore, reliable detection of main distribution valve refusal is very important.

[0011] The existing main and auxiliary refusal detection methods are as follows:

[0012] like Figure 2 As shown in the figure, there is a travel node in the closing direction of the main valve core, which is a normally closed point. When the main valve core moves in the closing direction, the travel node changes from a normally closed point to a normally open point. Figure 3 The figure shows the assembly diagram of the actual detection device. The main distribution valve core is connected to a convex block, and a touch switch is installed in the concave part of the convex block. When the main distribution valve core moves in the closing direction, the touch switch ball is pressed down, and COM and OFF change from normally closed to normally open, that is, the main distribution valve core operates normally, the signal changes from 1 to 0, and the main distribution refusal signal is reset. When the main distribution valve core does not move in the closing direction, the ball bounces up, COM and OFF are normally closed, and the touch switch reports a signal of 1, that is, the main distribution refusal signal is activated.

[0013] It can be seen from this that when the main distribution moves in the closing direction, if the travel node (normally closed point) is not disconnected, "main distribution refusal to move" will occur. When the unit speed continues to rise to 115%Ne, a passage is formed, and the accident shutdown circuit will be activated and the unit will shut down.

[0014] This touch switch only determines the main and auxiliary closing direction movement, and does not determine the main and auxiliary opening direction movement and balance position.

[0015] But the problem is that the current touch switch often cannot correctly reflect the status of the main valve core due to installation and matching. For example, if the main valve core moves too small, it will not be able to press down the small ball, resulting in a failure to report. At this time, in order to report, the touch switch will be adjusted to be more sensitive, but when the unit is adjusted normally with a small range, the position switch will frequently alarm. At this time, if the touch switch is installed too far away or the gap is too large, a failure to report will also occur.

[0016] In summary, the disadvantages of the existing main matching refusal to move detection method are: the position switch is difficult to adjust, and the compatibility with the main matching displacement stroke is not considered, resulting in the main matching displacement refusal to move signal, either a false alarm or a refusal to alarm.

[0017] In addition, there is also a solution that uses the main distribution displacement as an auxiliary judgment condition. Although it increases accuracy, it requires comprehensive judgment in the controller. Such a signal is not a direct mechanical signal, and an electrical part is added, which reduces reliability. For example, electrical power failure, fault, etc., cannot be reported. Summary of the invention

[0018] Purpose of the invention: The purpose of the present invention is to provide a device and method for detecting valve core refusal to move of a main pressure regulating valve of a turbine governor with high accuracy and reliability.

[0019] Technical solution: The device for detecting the spool refusal to move of the main pressure-regulating valve of a turbine governor described in the present invention comprises a spool displacement linkage rod, a screw and a position switch. The spool displacement linkage rod is connected to the end of the spool of the main pressure-regulating valve and can move synchronously with the spool of the main pressure-regulating valve; the screw is connected to the spool displacement linkage rod through a connecting block; a spring is sleeved on the screw, and nuts are arranged at both ends of the screw for axially limiting the spring; the position switch is a travel touch switch, which is fixedly arranged on the upper side of the spring; when the touch ball of the travel touch switch is in the recess of the spring, the touch ball stretches, and the travel touch switch reports a "0" signal; when the spring collides with the touch ball, the touch ball is compressed, and the travel touch switch reports a "1" signal; in the full stroke of the movement of the spool of the main pressure-regulating valve, the travel touch switch can report at least 2 cycles of "0, 1" signals.

[0020] Furthermore, the full stroke of movement of the valve core of the main pressure regulating valve is from the middle position to the closed position.

[0021] Furthermore, the position of the nut close to the connection block is fixed, and the position of the nut away from the connection block is adjustable; when the position of the nut is adjusted, the pitch of the spring changes accordingly.

[0022] Furthermore, the pitch of the spring is adjusted according to the displacement range of the main pressure regulating valve core. If the total displacement of the main pressure regulating valve core is small, the spring is compressed; if the total displacement of the main pressure regulating valve core is large, the spring is stretched.

[0023] Furthermore, end face blind holes and radial blind holes connecting the corresponding end face blind holes are respectively opened at both ends of the connecting block, and the screw rod and the valve core displacement linkage rod are respectively inserted into the end face blind holes at both ends of the connecting block and tightened by bolts threadedly connected to the radial blind holes.

[0024] Furthermore, the position switch is fastened to a screw rod, and the screw rod is mounted on an L-shaped bracket so as to be adjustable up and down; the initial position of the touch ball is adjusted to be located in the recess of the spring.

[0025] Furthermore, a vertical waist-shaped hole is opened on the side plate of the L-shaped bracket, and the screw rod is adjusted up and down based on the vertical waist-shaped hole.

[0026] The detection method of the device for detecting the valve core refusal to move of the main pressure regulating valve of the turbine governor of the present invention comprises:

[0027] Determine whether the governor main pressure regulating valve spool refusal signal is reported based on the following three conditions:

[0028] 1) The unit speed is greater than the first-stage overspeed setting speed;

[0029] 2) The guide vane opening is greater than the no-load opening;

[0030] 3) The number of "0, 1" signal cycles reported by the travel touch switch is less than the set number;

[0031] If the three conditions are met at the same time, the governor main pressure regulating valve spool refusal signal will be reported; if any one of the conditions is not met, the main regulating valve refusal signal will not be reported.

[0032] Furthermore, the first-level overspeed setting speed is 115% of the rated speed.

[0033] Furthermore, the set number of times is 2 times.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0035] (1) The present invention uses a spring in conjunction with a position switch to accurately identify the movement of the main pressure distribution valve core, and uses the number of times the position switch reports 0 and 1 signals, combined with the unit speed and the position of the guide vane to make a comprehensive judgment, rather than simply based on 0 and 1 signals. The main distribution refusal to move fault judgment is more accurate, concise, and direct (only based on mechanical principles).

[0036] (2) The use of pulse numbers can avoid and shield the signal reporting of the position switch caused by the slight movement of the valve core. If the traditional method, i.e. 0 and 1, is used, it is easy to frequently report the valve core position signal when the main distribution is normally adjusted, resulting in a large amount of useless information, occupying the memory, and thus covering other important information of the computer monitoring system.

[0037] In summary, the present invention can realize accurate identification of valve core refusal to move signals, without false movement or refusal to move, thus very reliably ensuring the long-term safe and stable operation of the hydropower unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the first-level overspeed shutdown in the prior art;

[0039] Figure 2 It is a schematic diagram of the main and auxiliary refusal detection node in the prior art;

[0040] Figure 3 It is an assembly diagram of a main distribution valve core and a main distribution refusal detection device in the prior art;

[0041] Figure 4 It is a structural schematic diagram of a device for detecting a valve core refusal to move of a main pressure regulating valve of a turbine governor provided by an embodiment of the present invention;

[0042] Figure 5 1 is an assembly diagram of a device for detecting a valve core refusal to move of a main pressure regulating valve of a turbine governor according to an embodiment of the present invention;

[0043] Figure 6 It is a flow chart of a method for detecting a valve core refusal to move of a main pressure regulating valve of a turbine governor provided by an embodiment of the present invention;

[0044] Figure 7 It is a schematic diagram of the main pressure distribution valve spool refusal to move detection in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings.

[0046] Attached Figures 1 to 7 The reference numerals in the figures are as follows:

[0047] 1. Valve core displacement linkage rod; 2. Connecting block; 3. Screw rod; 4. Spring; 5. Nut; 6. Position switch.

[0048] like Figure 4 and Figure 5 As shown, an embodiment of the present invention provides a device for detecting the valve core refusal to move of a main pressure regulating valve of a turbine governor, comprising a valve core displacement linkage rod 1, a screw rod 3 and a position switch 6. The valve core displacement linkage rod 1 is connected to the right end of the valve core of the main pressure regulating valve. The valve core moves to the left for closing and to the right for opening. The valve core displacement linkage rod 1 can move synchronously with the valve core of the main pressure regulating valve, reflecting the displacement and direction of the valve core movement.

[0049] The screw rod 3 is connected to the valve core displacement linkage rod 1 through the connecting block 2, so that the valve core displacement linkage rod 1, the connecting block 2 and the screw rod 3 can move as a whole. Specifically, the connecting block 2 is cylindrical, and its two ends are respectively provided with end face blind holes and radial blind holes connected to the corresponding end face blind holes. The screw rod 3 and the valve core displacement linkage rod 1 are respectively inserted into the end face blind holes at both ends of the connecting block 2, and are tightened by bolts threadedly connected to the radial blind holes. A spring 4 is sleeved on the screw rod 3, and nuts 5 are arranged on the screw rod 3 at both ends of the spring 4, which are used to axially limit the spring 4, wherein the position of the nut 5 close to the connecting block 2 is fixed, and the position of the nut 5 away from the connecting block 2 is adjustable.

[0050] The position switch 6 is installed on the upper side of the spring 4. The position switch 6 is a stroke touch switch. The position of the touch ball of the stroke touch switch and the spring 4 can be adjusted up and down. The initial position of the touch ball is adjusted to be located in the recess of the spring 4. Specifically, the position switch 6 is fastened to a screw rod, which is fixed to a vertical waist-shaped hole of a side plate of an L-shaped bracket by bolts. Based on the vertical waist-shaped hole, the screw rod can move up and down and is fixed by a nut, thereby realizing the adjustment of the upper and lower positions of the position switch 6 and the spring 4. The bottom plate of the L-shaped bracket is fixed on the ground. When the valve core moves in the closing direction, the position switch 6 will form a signal of "open-close-open-close-..." Since the displacement of the valve core is different in each power station, the position of the right-end nut 5 can be adjusted to adjust the pitch of the spring 4 (also called thread pitch, which is the distance between corresponding points on two adjacent thread profiles; it is also the distance that the thread line advances in the axial direction when the thread rotates one circle), so that in the full stroke of the main pressure distribution valve core (from the middle position to the closed position), the position switch 6 can report at least 2 cycles of "open-close" signals. This feature is used as a significant feature to detect whether the main distribution valve core moves in the closing direction and whether it moves to the limit position.

[0051] The embodiment of the present invention further provides a method for detecting the valve core refusal to move of a main pressure regulating valve of a turbine speed governor, and the device for detecting the valve core refusal to move of a main pressure regulating valve of a turbine speed governor according to the embodiment of the present invention is used, comprising:

[0052] according to Figure 4 and Figure 5 , connect all the components, fix the position switch 6, adjust the distance between the position switch 6 and the spring 4, so that the touch ball is extended in the concave part of the spring 4, that is, the open state, and reports a "0" signal; when the spring 4 collides with the touch ball, the touch ball is compressed, that is, the closed state, and reports a "1" signal.

[0053] According to the displacement range of the main pressure regulating valve core, adjust the nut 5 at the right end. If the total displacement of the main pressure regulating valve core is small, compress the spring 4; if the total displacement of the main pressure regulating valve core is large, stretch the spring 4. Ensure that the main pressure regulating valve core moves the full stroke (from the middle position to the closed position) to form a displacement of two cycles of the contact ball: open-close-open-close. This can increase the recognition and make the detection more precise.

[0054] like Figure 6 and Figure 7 As shown, according to the collected signal of the position switch 6, it is determined whether to report the valve core refusal signal of the speed regulator main pressure regulating valve in combination with the following three conditions:

[0055] 1) The unit speed is greater than the first-stage overspeed setting speed, which is set to 115% of the rated speed in this embodiment;

[0056] 2) The guide vane opening is greater than the no-load opening;

[0057] 3) The number of "0, 1" signal cycles reported by the stroke touch switch is less than 2 times; if it is less than 2 times, it means that the main valve core is stuck;

[0058] If the three conditions are met at the same time, the governor main pressure regulating valve spool refusal signal will be reported. This signal is sent to the unit emergency shutdown process to drive the governor emergency pressure regulating valve to complete the rapid closure of the guide vane to reduce the unit speed and protect the unit safety.

[0059] If any of the conditions is not met, the main distribution refusal signal will not be reported.

Claims

1. A device for detecting the valve core refusal to move of the main pressure regulating valve of a turbine speed governor, characterized in that: The invention comprises a valve core displacement linkage rod (1), a screw rod (3) and a position switch (6); the valve core displacement linkage rod (1) is connected to the end of the valve core of the main pressure regulating valve and can move synchronously with the valve core of the main pressure regulating valve; the screw rod (3) is connected to the valve core displacement linkage rod (1) through a connecting block (2); a spring (4) is sleeved on the screw rod (3), and nuts (5) are arranged at both ends of the spring (4) on the screw rod (3) for axially limiting the spring (4); the position switch (6) is a travel touch switch, which is fixedly arranged on the upper side of the spring (4); when the touch ball of the travel touch switch is in the concave part of the spring (4), the touch ball is extended, and the travel touch switch reports a "0" signal; when the spring (4) collides with the touch ball, the touch ball is compressed, and the travel touch switch reports a "1" signal; in the full travel of the valve core of the main pressure regulating valve, the travel touch switch can report at least two cycles of "0, 1" signals.

2. The device for detecting the valve core refusal to move of the main pressure regulating valve of the turbine speed governor according to claim 1, characterized in that: The full stroke of movement of the valve core of the main pressure regulating valve is from the middle position to the closed position.

3. The device for detecting the valve core refusal to move of the main pressure regulating valve of the turbine speed governor according to claim 1, characterized in that: The position of the nut (5) close to the connection block (2) is fixed, and the position of the nut (5) away from the connection block (2) is adjustable; when the position of the nut (5) is adjusted, the pitch of the spring (4) changes accordingly.

4. The device for detecting the valve core refusal to move of the main pressure regulating valve of the turbine speed governor according to claim 3, characterized in that: The pitch of the spring (4) is adjusted according to the displacement range of the main pressure regulating valve core. If the total displacement of the main pressure regulating valve core is small, the spring (4) is compressed; if the total displacement of the main pressure regulating valve core is large, the spring (4) is extended.

5. The device for detecting the valve core refusal to move of the main pressure regulating valve of the turbine speed governor according to claim 1, characterized in that: The two ends of the connection block (2) are respectively provided with end face blind holes and radial blind holes communicating with the corresponding end face blind holes. The screw rod (3) and the valve core displacement linkage rod (1) are respectively inserted into the end face blind holes at the two ends of the connection block (2) and tightened by bolts threadedly connected to the radial blind holes.

6. The device for detecting the valve core refusal to move of the main pressure regulating valve of the turbine speed governor according to claim 1, characterized in that: The position switch (6) is fastened to a screw rod, which is mounted on an L-shaped bracket in an adjustable manner up and down; the initial position of the touch ball is adjusted to be located at the concave position of the spring (4).

7. The device for detecting the valve core refusal to move of the main pressure regulating valve of the turbine speed governor according to claim 6, characterized in that: A vertical waist-shaped hole is provided on the side plate of the L-shaped bracket, and the screw rod is adjusted up and down based on the vertical waist-shaped hole.

8. A method for detecting the valve core refusal to move of the main pressure regulating valve of a turbine governor according to claim 1, characterized in that: include: Determine whether the governor main pressure regulating valve spool refusal signal is reported based on the following three conditions: 1) The unit speed is greater than the first-stage overspeed setting speed; 2) The guide vane opening is greater than the no-load opening; 3) The number of "0, 1" signal cycles reported by the travel touch switch is less than the set number; If the three conditions are met at the same time, the governor main pressure regulating valve spool refusal signal will be reported; if any one of the conditions is not met, the main regulating valve refusal signal will not be reported.

9. The detection method according to claim 8, characterized in that: The first-level overspeed setting speed is 115% of the rated speed.

10. The detection method according to claim 8, characterized in that: The setting number of times is 2 times.

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