JPH0768882B2 - Speed governor for steam turbine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention detects the rotation speed of a steam turbine and controls the opening / closing of a steam control valve based on the detected rotation speed.
The present invention relates to a speed governor having a function of keeping the rotation speed of the steam turbine at a predetermined value, and is particularly suitable for controlling the rotation speed of a steam turbine for a power plant.

[Conventional technology]

Conventionally, mechanical hydraulic governors (hereinafter abbreviated as MHG) and electrohydraulic governors (hereinafter abbreviated as EHG) have been widely adopted as speed governors for steam turbines. The MHG captures the turbine speed mechanically using, for example, centrifugal force, 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, the EHG captures the turbine speed as an electrical pulse signal, performs arithmetic processing on this in the EHG panel, and sends a control signal to the hydraulic device via the electric / hydraulic converter to send the steam control valve like the above MHG. Control the opening.

Since the control mechanism of the above-mentioned MHG is composed almost entirely of mechanical elements, it is robust and easy to maintain. It is also easy to elucidate the cause of the abnormality and take measures against it.

[Problems 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 governors, one of which is in standby as a backup.
Providing two sets of these leads to increase in complexity and size of the device and is not generally adopted.

On the other hand, most of the control mechanism of the EHG is composed of electronic circuits and electric parts, so it is superior to the MHG in responsiveness and interface with other automation equipment and computers. However, reliability is inferior to MHG due to problems such as loss of power supply, disconnection, electrical noise, and deterioration of electronic components. Therefore, the EHG needs to multiplex all or part of the important circuit. Generally, duplexing is used, one system is used for normal control, the remaining one system is used as a backup system, and when one system is abnormal, the system can be switched to the backup system without stopping the turbine operation. There is. Duplication of EHG, which is composed of expensive electronic parts, is one of the factors contributing to the cost up of steam turbines.

The present invention has been made in view of the above circumstances, and is inexpensive, high-performance, and highly reliable, having the robustness and maintenance of the MHG governor, and the responsiveness and interface of the EHG governor. An object is to provide a speed governor.

[Means for Solving the Problems]

In order to achieve the above object, the speed governor of the present invention has one system of EHG and one system of MHG installed side by side, and shares the hydraulic cylinder thereof. In addition, one of the above-mentioned two systems of governors is always operated, and the other is kept in standby as a spare.

[Action]

As mentioned above, if EHG and MHG are installed side by side and EHG is always activated and MHG is suspended, the responsiveness and interface of EHG are exhibited.

Therefore, the problem of poor reliability of EHG is
Highly reliable MHG backs up.

Furthermore, since EHG and MHG share a hydraulic cylinder,
The number of components is small and the manufacturing cost is low. Also, since two systems of governors are provided and one of them is always idle, maintenance is easy.

A component common to both EHG and MHG is a hydraulic cylinder that controls the opening of the steam flow control valve by 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 a hydraulic pressure. On the other hand, in the case of MHG using a rotary pendulum,
The hydraulic cylinder is controlled by a rotary pilot valve that converts the centrifugal force of the rotary pendulum into a linear motion and a mechanical signal of its displacement.

According to the present invention, another simple pilot valve is provided between both of the above signals and the hydraulic cylinder, and the hydraulic pressure to the hydraulic cylinder is sent or discharged through this pilot valve. During normal operation, the pressure oil to the hydraulic cylinder is sent through the rotary pilot valve of the MHG and the pilot valve which is one of the components of the present invention. The EHG controls the pilot valve during normal operation. 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 instead shifts to control by the rotary pilot valve.

〔Example〕

The overall configuration of the embodiment of the present invention will be described with reference to FIG.
The steam generated by the steam generator (not shown) is used as an emergency stop valve 27, a steam control valve chamber 26, and a control valve 2 built therein.
Flows through 5 into a steam turbine (not shown). Control valve 2
The drive device of 5 comprises a hydraulic cylinder 28, a hydraulic piston 29, a spring 30 and a valve rod 24. Piston 29 above
Compresses the spring 30 in which pressure oil is sent to the cylinder 28 to open the regulator valve 25 and increase the amount of steam to the turbine (load increase). When decreasing the steam amount (reducing the load), this operation is the opposite.

The electro-hydraulic governor (EHG) is a rotary gear 57 mounted on a turbine axle 56, a speed pick-up 55, an EHG panel 53, a hydraulic relay 50, a relay piston 49, a differential transformer 60, a servo valve 5
1, Lever 31, 34, 36, 47, Lever link 32, 35, 46, Lever fulcrum 33, 48, Electric wiring 52, 54, 61 and Oil pipe 51b, 51c.

Mechanical-hydraulic governor (MHG) is a speed / load regulator 4, worm 11, worm wheel 5, electric motor 10, rotary pendulum 15, rotary pilot valve 14, sleeve 13, lever 6, 9, 17, 21, 23, lever Links 7,16,18,22, lever fulcrums 8,20 and oil pipes 19b, 43
Composed of.

The hydraulic relay 38, the hydraulic relay 42, and the three-way switching valve 4 are the devices that prevent the control interference between the EHG and the MHG and shift to the MHG control to continuously perform the control function when the EHG fails.
The 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 described with reference to FIGS. 1, 2, and 3. As mentioned above, control during normal operation is performed by the EHG. The rotary gear 57 has a gear on its circumference. The speed detection pick-up 55 detects the rotation speed by the number of irregularities of the gear that passes within a certain time, converts it into a voltage in the EHG panel 53 as a pulse signal, and then according to a pre-installed program. Then, arithmetic processing is performed, and the servo valve 51 is driven via the electric wiring 52. Servo valve
51 converts the electric signal into hydraulic pressure and determines the position of the relay piston 49 in the hydraulic relay 50 via the oil pipe 51b or 51c.
If the rotational speed of the turbine were to drop, the relay piston 49 would rise and, via levers 47 and 36, the hydraulic relay
The pilot valve 40 in 38 and 42 is raised. As a result, the oil hole 42b of the hydraulic relay 42 is opened and pressure oil is supplied to the hydraulic cylinder 28 via the oil pipes 19b and 43. The pressure oil compresses the spring 30 to raise the piston 29 and increase the valve opening of the regulator valve 25. Ascending valve rod 24 is lever 31, lever link 3
The increase of the valve opening is stopped at a position where the oil hole 42b is completely closed by the pilot valve 40 via the lever 34, the lever link 35 and the lever 36, and one control operation is completed. Conversely, when the turbine speed increases, the control operation opposite to the above is performed.

While the turbine is controlled by the EHG, the MHG must have its controls excluded to prevent interference with the EHG. This is because the MHG rotary pilot valve 14 provided on the path through which the pressure oil in the oil pipe 19a reaches the cylinder 28
You have to make 3a always open. By using the speed / load controller 4 and the lever 9 as means for this purpose, the sleeve 13 is automatically moved against the movement of the pilot valve 14 which moves up and down according to the change in speed while maintaining a certain offset amount. To follow. This amount of offset is necessary to minimize the fluctuation of the amount of steam flowing into the turbine when the control shifts to MHG, which will be described later.

The speed detected by the speed detector 55 is processed by the EHG board 53 for a signal necessary for holding the offset amount, and is sent to the electric motor 10 as a pulse signal through the electric wiring 58. A worm 11, which is rotated by the motor shaft, drives a worm gear 5 mounted on the speed / load regulator 4. A male screw is formed on the upper portion of the adjuster 4 and is screwed into a female screw provided on the bracket 2. Thereby, the rotation of the worm gear 5 is converted into the vertical movement of the adjuster 4, and the position of the sleeve 13 is determined via the lever link and the lever 9. The differential transformer 70 feeds back to the EHG board 53 that the correct position of the sleeve 13 has been obtained by the given signal.

When the control of the EHG is disabled for some reason, the signal activates the three-way switching valve 44 via the electric wiring 62. Second
The figure shows the state at this time. The pressure oil pressing the relay piston 39 downward via the switching valve 44 and the oil pipe 41b is discharged from the switching valve 44. As a result, due to the restoring force of the compressed spring 37, the pilot valve 40 rapidly rises to fully open the oil hole 42b. The pressure oil to the hydraulic cylinder 28 tries to fully open the regulator valve 25 through the oil pipes 19b and 43. The upward movement of the piston 29 constitutes the restoring mechanism lever 23, lever link 22, lever 21, lever link 18, lever
17, The sleeve 13 is raised by the lever link 16 and the lever 9 to try to close the oil hole 13a. On the other hand, since the rotational speed of the turbine increases as the amount of steam flowing into the turbine increases, the rotary pendulum 15 opens to the outside to operate the rotary pilot valve downward. This operation also closes the oil hole 13a. The time required for this closing 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 holes (13a and 13c) are completely blocked,
With one of the oil holes (42b and 42d) completely opened, the transfer of control to the MHG is completed. That is, the control amount of supply (or discharge) of the pressure oil of the oil pipe 19a to the hydraulic cylinder 28 depends on the opening degree of the oil holes 13a and 13c obtained by the relative relationship between the position of the pilot valve 14 and the position of the sleeve 13. The turbine speed (or load) is controlled by the MHG. During this time, the EHG that has failed can be repaired, so the maintainability is good.

Fig. 3 shows the change in turbine load that occurs when the control shifts from EHG to MHG on the governor characteristic diagram. The vertical axis represents the set position of the speed / load adjusting device 4, and the horizontal axis represents the rotational speed of the turbine. Upper limit of vertical axis (0
%) Is given by the low speed stopper 1 and the lower limit (100%) is given by the high speed stopper 3. The load "A" point due to EHG control moves to the load "B" point by the MHG that has always been offset and has followed up, and a load increase of ΔL is given.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The steam turbine speed governor of the present invention has an excellent practical effect of having a simple structure, good responsiveness, and high reliability.

[Brief description of drawings]

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

Claims (1)

[Claims] 1. A rotation speed of a steam turbine is detected, and the opening degree of a steam control valve provided in a pipeline for supplying main steam to the steam turbine is automatically controlled based on the detected rotation speed. In a speed governing device for maintaining the rotation speed of the steam turbine at a predetermined value, (a) a hydraulic cylinder for opening and closing the steam control valve is provided, and (b) pressure oil supplied to the hydraulic cylinder is supplied. An electro-hydraulic governor to be controlled is provided, and (c) a pilot valve of a mechanical governor is provided upstream of the pilot valve of the electro-hydraulic governor, and (d) during normal operation, both of the governors are The structure is such that one of the pilot valves is operated and the other is stopped, and (e) when one of the governors does not operate normally,
A speed governor for a steam turbine, characterized in that the control function of the other governor is substituted.