JPH01190902A - Steam turbine governor - Google Patents

Abstract

PURPOSE:To improve reliability by installing the pilot valve of a mechanical type governor on the upstream side of the pilot valve of an electronic hydraulic type governor. CONSTITUTION:The pressurized oil supplied into a hydraulic cylinder 28 for opening/closing-driving a steam reducing valve 25 is controlled by an electronic hydraulic type governor consisting of an EHG board. The pilot valve 14 for mechanical governor is installed on the upstream side of the pilot valve 40 of the electronic hydraulic type governor, and when the electronic hydraulic type governor does not operate normally, the mechanical governor is used in substitution. Therefore, the reliability of the speed governor can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects the rotational speed of a steam turbine, and controls the opening and closing of a steam control valve based on the detected rotational speed.
The present invention relates to a speed governor having a function of keeping the rotational speed of the steam turbine at a predetermined value, and is particularly suitable for controlling the rotational speed of a steam turbine for a power generation plant.

[Conventional technology]

Conventionally, mechanical hydraulic governors (hereinafter referred to as MHG) and electrohydraulic governors (hereinafter referred to as E) have been used as speed governors for steam turbines.
(abbreviated as HG) has been widely adopted. The MHG mechanically captures the speed of the turbine using centrifugal force, for example, and amplifies the mechanical displacement using a lever mechanism or hydraulic device to control the opening of the steam control valve. On the other hand, EHG captures the speed of the turbine as an electrical pulse signal, processes this in the EHG panel, and sends a control signal to the hydraulic system via the electric/hydraulic converter, which controls the steam control valve like the MHG mentioned above. Controlling the Opening Degree The M'HG described above is robust and easy to maintain and inspect because its control mechanism is almost entirely composed of mechanical elements. It is also easy to find out the cause of the abnormality and take countermeasures against it.

[Problem to be solved by the invention]

In order to further improve the reliability of the steam turbine plant as a whole, it is desirable to install two speed governor systems and keep one of them on standby as a backup.
Providing two sets of Gs would complicate and increase the size of the device, so it is not generally adopted.

On the other hand, since most of the control mechanism of EHG is composed of electronic circuits and electrical parts, it has better responsiveness and interface with other automation equipment, computers, etc. than MHG. However, it is less reliable than MHG due to problems such as loss of power, disconnection, electrical noise, and deterioration of electronic components. For this reason, it is necessary to multiplex all or some of the important circuits of the EHG. Generally, the system is duplicated, with one system used for normal control and the remaining system on standby as a backup, so that in the event of an abnormality in one system, the system can switch to the backup system without stopping turbine operation. . The duplication of EHG, which is made up of expensive electronic components, is one of the factors that increases the cost of steam turbines.

The present invention was made in view of the above-mentioned circumstances, and is an inexpensive, high-performance, and highly reliable control device that has the robustness and maintainability of an MHG governor and the responsiveness and interface of an EHG governor. The purpose is to provide a speed device.

[Means to solve the problem]

In order to achieve the above object, the speed governor of the present invention includes one system of EHG and one system of MHG, and shares the hydraulic cylinders thereof. In addition, one of the two governor systems is operated at all times, and the other is kept on standby as a standby.

[Effect]

If EHG and MHG are installed together as described above, and the EHG is always activated and the MHG is inactive, the responsiveness and interface characteristics of the EHG will be exhibited.

Therefore, the problem of poor reliability, which is a disadvantage of EHG, is backed up by highly reliable MHG.

Furthermore, since the EHG and MHG share a hydraulic cylinder, the number of component parts is small and the manufacturing cost is low. Furthermore, since two systems of governors are provided, one of which is always inactive, maintenance is easy.

A common component in both EHG and MHG is a hydraulic cylinder that controls the opening degree of the steam flow rate control valve using hydraulic pressure. In the case of EHG, the hydraulic cylinder is controlled by an electric/hydraulic conversion device (hereinafter abbreviated as servo valve) that converts an electric signal into oil pressure. On the other hand, MH using a rotating pendulum
In the case of G, the hydraulic cylinder is controlled by a mechanical signal in the form of a rotary pilot valve and its displacement, which converts the centrifugal force of the rotary pendulum into linear motion.

The invention provides another simple pilot valve between both of the above signals and the hydraulic cylinder, through which the hydraulic pressure to the hydraulic cylinder is delivered or discharged. During normal operation, pressure oil to the hydraulic cylinders is delivered through the rotary pilot valve of the MHG and the pilot valve, which is one of the components of the present invention. During normal operation, the pilot valve is controlled by EHG. During this time, the MHG rotary pilot valve is excluded from the control range. When the EHG fails, the pilot valve is automatically removed from the control range and control is transferred to the rotary pilot valve instead.

〔Example〕

The overall configuration of an embodiment of the present invention will be explained using FIG.

Steam generated by a steam generator (not shown) is passed through an emergency stop valve 27. It flows into a steam turbine (not shown) through a steam control well 26 and a control valve 25 built therein.

The driving device for the regulating valve 25 is a hydraulic cylinder 28. Hydraulic piston 29. It is composed of a spring 30 and a valve stem 24. When pressure oil is sent to the cylinder 28, the piston 29 compresses the spring 30 and opens the control valve 25 to increase the amount of steam to the turbine (increase the load), and to decrease the amount of steam (reduce the load). , this movement is the opposite.

The electro-hydraulic governor (EHG) is a rotating gear 57 . mounted on the turbine axle 56 . Speed pickup 55. E
HG board 53. Hydraulic relay 50/relay piston 49. Differential transformer 60. Servo valve 51, levers 31, 34, 3
6,47. Lever links 32, 35, 46. Lever fulcrum 33.48° Electric wiring 52, 54.61 and oil pipe 5
It consists of 1b and 51c.

Mechanical hydraulic governor (MHG) is a speed/load regulator 4
．． Warm 11. Worm wheel 5°, electric motor 109 rotating pendulum 159 rotating pilot valve 14, sleeve 13. Lever 6.9, 17, 21゜23, lever link 7.16
, 18, 22. Lever fulcrums 8, 20 and oil pipes 19b, 4
Consists of 3.

The hydraulic relay 38. is a device that prevents mutual control interference between the EHG and MHG and shifts to MHG control in the event of EHG failure to continuously perform the control function. Hydraulic relay 4
2. Three-way switching valve 44. Differential transformer 70. Electrical wiring 58
, 62, 71 and oil pipes 41a, 41b.

Next, the operation of the embodiment of the present invention will be explained using FIGS. 1, 2, and 3. As mentioned above, control during normal operation is performed by the EHG.

The rotating gear 57 has gears on its circumference. The speed detection pickup 55 detects the rotational speed by the number of concavities and convexities of the gear passing within a certain period of time, converts this as a pulse signal to the internal pressure in the EHG panel 5, and then performs arithmetic processing according to a pre-installed program. Then, the servo valve 51 is driven via the electric wiring 52. The servo valve 51 converts an electric signal into hydraulic pressure and determines the position of the relay piston 49 in the hydraulic relay 5o via an oil pipe 51b or 51c. If the rotational speed of the turbine were to decrease, the relay piston 49 would rise, causing the hydraulic relay 38 and the pilot valve 4o in the hydraulic relay 42 to rise via the levers 47 and 36. As a result, the oil hole 42b of the hydraulic relay 42 opens and pressure oil is supplied to the hydraulic cylinder 28 via the oil pipes 19b and 43. The pressure oil compresses the spring 3o and raises the piston 29.

The valve opening degree of the control valve 25 is increased. The rising valve stem 24 is moved by the lever 31. Lever link 32. When the pilot valve 40 is moved via the lever 34, the lever link 35, and the lever 36 to a position where the oil hole 42b is completely closed, the increase in the valve opening degree is stopped, and one control operation is completed. On the other hand, when the speed of the turbine increases, a control operation opposite to the above is performed.

While the turbine is controlled by the EHG, the control of the MHG must be excluded to prevent interference with the EHG. The pilot valve 14 must keep the oil hole 13a open at all times.

As a means for this, the speed/load regulator 4 and lever 9 are used to automatically move the sleeve 13 while maintaining a certain amount of offset against the movement of the pilot valve 14, which moves up and down in response to changes in speed. to follow. This offset amount is necessary to minimize fluctuations in the amount of steam flowing into the turbine when control is transferred to MHG, which will be described later.

The speed detected by the speed detector 55 is processed by the EHG board 53 into a signal necessary to maintain the offset amount, and is sent to the electric motor 10 as a pulse signal via the electric wiring 58 . A worm 11 rotated by the motor shaft drives a worm gear 5 attached to a speed/load regulator 4. A male thread is formed on the upper part of the regulator 4, and is screwed into a female thread provided on the bracket 2. As a result, the rotation of the reworm gear 5 is converted into the vertical movement of the regulator 4, and the sleeve 13 is moved through the lever link 7 and the lever 9.
determine the position of The differential transformer 7o feeds back to the EHG board 53 that the correct position of the sleeve 13 has been obtained by the applied signal.

E: When control of H and G becomes impossible for some reason.

The signal operates the three-way switching valve 44 via the electrical wiring 62. FIG. 2 shows the state at this time.

Relay piston 39 via switching valve 44 and oil pipe 41b
The pressure oil that was pressing downward is discharged from the switching valve 44. As a result, the pilot valve 4o rapidly rises due to the restoring force of the compressed spring 37, and the oil hole 42b
fully open. Pressure oil to the hydraulic cylinder 28 is supplied to the oil pipe 19.
The control valve 25 is attempted to be fully opened through steps b and 43.

The upward movement of the piston 29 is controlled by the lever 2 that constitutes the restoring mechanism.
3゜lever link 22. Lever 21. lever link 18
, lever 17. The sleeve 13 is raised by the lever link 16 and the lever 9 in an attempt to close the oil hole 13a. On the other hand, as the amount of steam flowing into the turbine increases, its rotational speed increases, so the rotary pendulum 15 opens outward and moves the rotary pilot valve downward. This operation also applies to oil hole 1.
3a is occluded. The time required for this closure can be achieved in a short time because the sleeve 13 has already followed the position of the pilot valve 14 as an offset amount. Oil hole (13a
and 13c) are completely closed and one of the oil holes (42b and 42d) is completely open, and the transfer of control to the MHG is completed. That is, the control amount of the supply (or discharge) of pressure oil from the oil pipe 19a to the hydraulic cylinder 28 is determined by the oil hole 13a obtained by the relative relationship between the position of the pilot valve 14 and the position of the sleeve 13.
The speed (or load) of the turbine is controlled by the MHG. During this time, the EHG that has failed can be repaired, so maintenance is easy.

FIG. 3 shows on a governor characteristic diagram how the turbine load fluctuates when control is transferred from EHG to MI-IG. The vertical axis represents the set position of the speed/load adjustment device 4, and the horizontal axis represents the rotational speed of the turbine.
The upper limit (0%) of the vertical axis is the low speed stopper, the lower limit (100%)
%) are respectively given by high speed stops 3. E
This shows a state in which the 11 points of load "A" under HG control are shifted to point "B" of load and a load increase of ΔL is applied by the MHG, which has always been followed with an offset.

〔Effect of the invention〕

The steam turbine governor of the present invention has excellent practical effects such as a simple configuration, good responsiveness, and high reliability.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the arrangement of the constituent devices and the operation of each device of the entire steam turbine equipment provided with one embodiment of the speed governor according to the present invention. FIG. 2 is an explanatory diagram showing the operation of the switching device when the EHG fails and shifts to MHG control. FIG. 3 is a characteristic chart showing load fluctuations caused by switching. 39... Relay piston, 40... Pilot valve. 41b... Oil pipe, 44... Three-way switching valve, 62...
Electric wiring.

Claims (1)

[Claims] 1. The rotational speed of a steam turbine is detected, and based on the detected rotational speed, the opening degree of a steam control valve provided in a pipe that supplies main steam to the steam turbine is automatically adjusted. In a speed governor that controls and maintains the rotational speed of the steam turbine at a predetermined value, (a) a hydraulic cylinder that opens and closes the steam control valve is provided, and (b) a hydraulic cylinder is supplied to the hydraulic cylinder. An electro-hydraulic governor for controlling pressure oil is provided, and (c) a pilot valve for a mechanical governor is provided upstream of the pilot valve of the electro-hydraulic governor, and (d) both governors are operated during normal operation. (e) When one of the governors ceases to operate normally,
A speed governor for a steam turbine, characterized in that the control function is replaced by another governor.