JPS5977008A - Apparatus for controlling position of turbine valve operation part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a control device for controlling the position of a turbine valve operating section, particularly a steam turbine control valve operating section.

[Prior art and its problems]

Such a device is disclosed in German Patent No. 2°727.
No. 969. In the device described in this specification, an independent position control loop is provided for each turbine valve in a valve group of a plurality of turbine valves. Each of these parallel controlled control loops consists of a hydraulically operated cylinder, an electrohydraulic transducer two position transmitter, and an electrical position adjuster. The role of such a control loop is to position, in response to an electrical command signal or setpoint value signal, the power piston of the hydraulically actuated cylinder and thus also the valve body of the turbine valve, which is connected to it via the piston rod, and to control the load. It is to be held in this position regardless of the However, if a failure occurs in one of the devices forming the control loop, the power piston of the hydraulically actuated cylinder occupies one of its two end positions, so that there is no longer a correspondence between the setpoint value signal and the position of the power piston. It will not be established.

As long as such a course moves the power piston in the closing direction, i.e. if the fault direction is the closing position of the hydraulic actuating cylinder, this is considered a safe position and is permissible. However, if the power piston moves in the opening direction due to a failure in the control loop, ie the failure direction is the opening position of the hydraulic operating cylinder, this cannot be tolerated. 7:J), which leads to the opening of the steam intake point to the turbine, for example. For this reason, in known controls for controlling the position of turbine valves, a protection device is added to move the power piston in the direction of closing the turbine valve in the event of a fault in the control loop. This ensures that the fault direction is always the closed position of the hydraulic actuating cylinder, regardless of the fault type. A protection device monitors the synchronous movement of the power pistons of the individual hydraulically operated cylinders in order to be able to detect the occurrence of a fault in one of the parallel-controlled control loops of the valve group, thereby exceeding the permissible limits of the other power pistons. The power piston, which is in a position that deviates from the position, can be moved in the direction of closing the turbine valve. However, monitoring such synchronous operations requires considerable equipment expenditure. Furthermore, in the case of synchronous motion monitoring, it is assumed that the control loops that are controlled in parallel have exactly the same dynamic behavior, which remains constant during operation.

[Purpose of the invention]

It is an object of the invention to provide a turbine valve actuator position control device of the type mentioned at the outset, which, in the event of a fault in the control loop, can be implemented at low cost and at the same time improves the dynamic behavior of a series control loop.
Irrespective of this, the purpose is to ensure rapid closure of the turbine valve of a failed control loop. A device comprising a hydraulically actuated cylinder with a power piston for controlling the opening of a turbine valve and a regulating element for comparing an actual value signal derived from the position of the power piston with a setpoint value signal and generating a signal corresponding to the control deviation. an electro-hydraulic converter that converts a signal corresponding to the control deviation into a fluid flow for positioning the power piston, and a protection device that operates the power piston in a direction to close the turbine valve in the event of a fault in the position control loop. In the control device, the control device compares the control deviation with a certain limit value, and when this limit value is reached, operates the power piston in the direction of closing the turbine valve;
This limit value is achieved in that the limit value is variable as a function of the temporal behavior of at least one disturbance quantity that interferes with the position control loop.

The invention is based on the recognition that in the event of a fault in the control loop, the power piston of the hydraulically actuated cylinder can no longer follow the electrical command signal, and that the resulting deviation in correspondence can be detected by monitoring the control deviation. . To this end, the protection device may be configured to compare the control deviation with a certain limit value, and to move the power piston in the direction of closing the turbine valve when this limit value is reached.

However, since the protection device must not react to control deviations that occur during normal operation, the limit value had to be selected to be larger than the control deviations that inevitably occur during the settling process, for example. However, the reaction limits of the protection device thus selected are such that, on the other hand, failures in the control loop are detected early.

The result is that the start of rapid closing of the turbine valve is too late. Therefore, the present invention further provides that the limit value should not be set constant, but as a time-related set value, so that the response limit of the foot protection device can be flexibly adapted to the dynamic behavior of the control loop caused by the amount of disturbance. It is based on the recognition that this should be the case. Therefore,
The limit value is designed to be variable as a function of the temporal behavior of at least one disturbance variable interfering with the position control loop. Note that in the present invention, the definition of the amount of disturbance includes the command amount, that is, the position target value. This ensures that the farm maintenance device does not react in the event of an inevitable control deviation caused by disturbance quantities, but immediately responds to the associated turbine valve in the event of a control deviation caused by a fault in the control loop. is guaranteed to initiate a quick closure.

In an advantageous embodiment of the invention, the limit value has a first limit value portion which can be set constant and at least one further limit value portion which is derived from the time course of the disturbance amount interfering with the position control loop. It is composited from the limit value part. In this case, a first limit value part, which can be set at 4 constants, determines the reaction limit of the φ device in the event of a failure of the control loop in steady state, while another limit value part is related to the disturbance quantity. to flexibly create a shift in the response limit. In order to form a further limit value section, it is expedient to provide a disturbance quantity monitoring device d, after which a differential element or a dynamic element with a similar behavior is connected. If a first-order or higher-order time element is connected after the differential element, it is possible to have a certain influence on another time-related limit value part through the empirically determined setting of the time element. .

In one preferred embodiment of the present invention, a differential element having temporal behavior is connected after the disturbance amount monitoring device. An absolute value forming circuit connected after the differential element with temporal behavior allows its output to be the absolute value of the input. An asymmetric smoothing circuit connected after the absolute value forming circuit makes it possible to define the dynamic characteristics of the time-related separate limit value part through an empirically defined differential element and the settings of the asymmetric smoothing circuit. do.

Since the dynamic behavior of the position control loop is primarily caused by a change in the setpoint signal, one clever embodiment of the device according to the invention provides a first limit value part whose limit value can be set constant. The second value derived from the temporal behavior of the target value signal
It is composited from the limit value part of.

However, the dynamic behavior of the position control loop may also be caused by the pressure of the fluid supply as a disturbance quantity. In such a case, the limit value can be set as a constant first limit value part, a second limit value part derived from the time behavior of the setpoint value signal, and a time-dependent limit value part of the pressure of the fluid supply. and a third limit value part derived from the behavior.

In order to form the second limit value part, it is advantageous to provide a first differential element which is provided with a setpoint value signal and has a temporal behavior, after which 10) the absolute value formation circuit and the first
By connecting the asymmetric smoothing circuit of , it is possible to determine the dynamic characteristics of the limit value portion of M2 through the empirically determined settings of the first differential element and the second asymmetric smoothing circuit.

Similarly, to form a third limit value part, a second
Connect the differential elements of. Thereafter, by connecting the second absolute value forming circuit and the second asymmetric smoothing circuit, the third limit value portion can be determined through the empirically determined settings of this differential element and the second asymmetric smoothing circuit. Dynamic characteristics can be determined.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings. The same parts are given the same reference numerals throughout the drawings.

FIG. 1 shows a very simplified control device for controlling the position of a turbine valve actuator. This device has a hydraulic operating cylinder 1, whose power piston 2 controls the opening of a turbine valve (not shown in the drawing) via a piston rod 3. When the facing side is not pressurized by pressure fluid, it is pushed into the first end position by the spring 4. This first end position corresponds to the closed position of the turbine valve. When the side of the power piston 2 facing the piston rod 3 is pressurized by a pressure fluid, the power piston 2 is pushed against the force of the spring 4 into a second end position corresponding to the maximum possible open position of the turbine valve. It will be done.

In order to enable good braking during positioning of the power piston 2, the power piston 2 is constructed as a double-acting piston, the side of which opposite the piston rod 3 is compressed during movement in the closing direction. It is pressurized by fluid, and is depressurized when moving in the opening direction.

The position of the turbine valve in the operating range between the two road end positions or the positioning of the power piston 2 is determined by the cylinder space 7 located on both sides of the power cylinder 2 in relation to the setpoint value signal S! J) and controlled by the flow of fluid into this space. For this purpose, the actual position value of the power cylinder 2 is determined by a position transmitter 5 and fed to an electrical position adjuster 6 as an electrical real-line value signal. The electric position controller 6, which is also supplied with the setpoint value signal S, first determines the control deviation of 5 as the difference signal between the setpoint value signal S and the actual value signal.

Subsequently, this difference signal is amplified in the electric position adjuster 6 and is applied to the electro-hydraulic transformer 7 as a signal corresponding to the control deviation x,=t.

The electro-hydraulic converter 7 has a 3/4 way spool and is used as a pilot-operated servo valve to block fluid flow at a central position.
It's been done. In order to control the flow of fluid from and into the cylinder space in which the power piston 2 is located, the cylinder space is connected to a corresponding control channel of the electro-hydraulic converter 7! (!- is connected. Furthermore, the electro-hydraulic converter 7 is
The drawing shows a pump P and a drain A connected to a fluid supply device as shown.

The position control loop of the turbine valve is controlled by the hydraulically operated cylinder 1. It consists of a heavy oil converter 79, a position transmitter 5, and an electric position adjuster 6. If a failure occurs in one of these devices forming the chair control loop-'pJfN, both #! It will occupy one end.

To ensure that the direction of failure is towards the closed position of the hydraulic operating cylinder 1, it is designated as a whole with the reference SB.
A protective device is provided. This protection device detects faults in the control loop early and triggers quick closing of the turbine valve via a quick closing signal ss.

Therefore, the quick closing signal SS is the quick closing solenoid valve S8-M.
The turbine valve is quickly closed by the force of the spring 4, since this solenoid valve connects the cylinder space facing the spring 4 with the drain A1 of the fluid supply device for depressurization.

The protection device SE detects the control deviation, which is formed as the difference between the setpoint value signal S and the actual value signal (2).

It includes a limit value device GE which is compared with a limit value G and triggers a quick closing signal SS when this limit value G is reached.

The variable limit value G is compounded from a first constant settable limit value portion Gl and a further time-dependent limit value portion GW. This further limit value portion GW is derived from the temporal behavior of the disturbance amount 8G that interferes with the position control loop. For this purpose, a disturbance amount monitoring device SGA is provided that detects the disturbance amount 8G that interferes with the control loop and applies it to the differential element having the temporal behavior BZ. An absolute value forming circuit AWB and an asymmetric smoothing circuit UB are connected after this differential element. The first limit value portion G1 forms a predetermined reaction limit of the protective bag R8E in the steady state of the control loop, while the further limit value portion GW is dependent on the dynamic behavior of the control loop caused by disturbances i8G. Flexible adaptation of response limits. The latter has a limit value device GE in the drawing.
It is indicated by a dashed line inside the block.

In the embodiment of the protection device SF shown in FIG. 1, it was generally assumed that the dynamic behavior of the control loop is caused by disturbance quantities interfering with the control loop. However, for flexible adaptation of the reaction limits, two or more disturbance quantities that interfere with the control loop can also be used. First of all, the target value signal S is considered as the amount of disturbance. In some cases, the pressure P of the fluid supply device can also cause the temporal behavior of the control loop. A pressure monitoring device DA for pressure P, which is regarded as one of the disturbance amount monitoring devices 8GA, is shown in FIG. 1 between the pump P (!: electro-hydraulic converter 7).

FIG. 2 shows a first exemplary embodiment of a storage device with a position control loop, referenced SE', in a block circuit diagram. As can be seen from this figure, the control loop is connected to the position adjuster 6. Electro-oil converter7. It consists of a hydraulic operating cylinder 1 and a position transmitter 5. The position adjuster 6 includes an adjustment element 61 and an electric amplifier 62, the adjustment element 6
1 compares the target value signal S with the actual value signal to determine the control deviation.

A protection device 8E'l, an addition element Ag, a limit value switch GW5 connected after it, a first differential element DZ1 having temporal behavior, and a first absolute value forming circuit AW
BI and a first asymmetric smoothing circuit VG1.

The addition element Ag includes a first limit value portion Gl that can be set to a constant value, a first differential element DZI, and a first absolute value forming circuit A.
Through WB J and the first asymmetric smoothing circuit UGI,
A time-related second limit value portion G2 derived from the setpoint value signal S and a control deviation R7 are provided. The limit value switch GW5 set to the zero signal fix causes the control deviation R to be divided into a first limit value portion G1 and a second limit value portion G2.
When the sum of the quick-closing solenoid valves SS-MvI and n is reached or exceeded, i.e. when the input signal of the limit value switch GwS reaches O or a value greater than
Gives a quick closing signal, (J3.

FIG. 3 shows a position control loop and a second embodiment of the protection device, referenced SE1, in a block circuit diagram. In this embodiment, in addition to the setpoint value signal S, the pressure p of the fluid supply device may also interfere with the control loop as a disturbance quantity. Therefore, the protective device SD 11
The protection device SEI shown in FIG. 2 has achieved the following points. a second differential element with temporal behavior, referenced DZ2; a second absolute value forming circuit, referenced A to VB2; and a second differential element, referenced UG2.
A second asymmetric smoothing circuit, marked 2, is added, thereby forming a third limit value portion G3 derived from the temporal behavior of the pressure p of the fluid supply device.

This third limit value portion G3 is also in this case referenced A.
g is given to the addition element labeled l. The limit value switch Gws thus reacts when the control deviation reaches or exceeds the sum of the first limit value portion Gl, the second limit value portion G2 and the third limit value portion G3.

In the following, the temporal behavior of the device of FIG. 2 after a change in the setpoint value signal S will be explained in more detail with reference to FIGS. 4 to 8. First, in FIG. 4, the target value signal S is shown with time t on the horizontal axis, and the change in the target value signal is shown as a ramp function.

In FIG. 5, the course of the actual value signal engineering is shown with time t on the horizontal axis. This is the typical behavior of a control loop during a settling process, in which the actual value signal {circle around (2)} follows the setpoint signal change shown in FIG. 4 with some delay and overshoot.

In Fig. 6, the behavior of the control deviation is shown with time t as the horizontal axis, and the control deviation is shown in Fig. 4, the behavior of the target value signal S shown in Fig. 1, and the actual value shown in Fig. 5. This occurs as a difference from the behavior of signal I.

In FIG. 7, the behavior of the limit value G is shown with time t as the horizontal axis. and a second limit value part G2 derived from the general behavior. From this figure, it can be seen that the limit value G, before the change in the setpoint signal shown in FIG.
This corresponds to a first limit value portion G1 that is set constant. However, during the settling process, the second limit value part G2 adapts to the dynamic behavior of the control loop and expands the limit value G.

Finally, in FIG. 8, the limit value G with the time axis t on the horizontal axis and the control deviation value plotted with a chain line on the time axis tfc are shown in a convenient form for comparison. As can be seen from this figure, the curve of the limit value G includes the curve of the control deviation. However, this only holds true when no faults occur within the control loop. In the event of such a fault, the control deviation R reaches the limit value G, which leads to the immediate initiation of a rapid closing of the turbine valve by the protection device SEI shown in FIG.

In the embodiment described above, the protection device SE.

SEI and SD I+ are used for monitoring the position control of turbine valves, such as regulating valves or directional valves, for example. However, such a protection device is applicable not only to this application but also to monitoring control loops in general.

〔Effect of the invention〕

As explained above, in the present invention, a failure in a control loop is detected by a protection device based on a control deviation between an actual value signal indicating the position of a power piston of a hydraulic actuator for controlling a turbine valve and a target value signal. When the turbine valve is operated in the closing direction, the limit value of the control deviation at which the protection device starts the closing operation is not set as a fixed limit value as in the past, but the amount of disturbance including the command value that interferes with the control loop. Since the variable limit value is related to the temporal behavior of This eliminates the inconvenience of the protection device responding erroneously even when the temperature increases. In addition, by doing the above, the contradiction of having to set a limit value larger than the value truly necessary for cough maintenance in order to avoid erroneous responses as in the past is resolved, and failures within the control loop are ensured. The protection device will be able to detect this and take the necessary action to ensure that the turbine valve is closed, thereby improving the reliability of steam turbine operation.

[Brief explanation of the drawing]

FIG. 1 is a significantly simplified diagram of a turbine valve actuator position control device and associated protection device; FIG. 2 is a block circuit diagram of a first embodiment of the position control loop and protection device;
FIG. 3 is a block circuit diagram of a second embodiment of the position control loop and protection device, FIG. 4 is a diagram showing the time course of the target value signal when the ramp-shaped target value signal changes, and FIG. 4 is a diagram showing the time course of the actual value signal after the target value signal change, FIG. 6 is a diagram showing the time course of the control deviation after the target value signal change shown in FIG. 4, Figure 7 is a diagram showing the time course of the limit values that determine the response of the protective device after the target value signal change shown in Figure 4, and Figure 8 is a diagram showing the movement of the position control loop initiated by the target value signal change. 7 shows the curves shown in FIGS. 6 and 7 in a convenient form for comparison in order to explain the flexible adaptation of the limit values to the normal behavior; FIG. 1...Hydraulic operation cylinder, 2...Power piston, 3...
・Piston socket, 4... Spring, 5... Position transmitter, 6
... Position e regulator, 7... Battery converter, A, WB/absolute value forming circuit, DZ... Differential element, G... Limit value, G
1, G2, G3...limit value part, R...control deviation,
S...Target value signal, SE...Logging device, 8G...
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Claims (1)

[Scope of Claims] 1) A control device for controlling the position of a turbine valve operation section, particularly a steam turbine control valve operation section, comprising a hydraulic operation cylinder having a power piston that controls the opening degree of the turbine valve;
an adjusting element for comparing the actual value signal derived from the position of the power piston with a setpoint value signal and generating a signal corresponding to the control deviation and converting the signal corresponding to the control deviation into a fluid flow for positioning the power piston; battery converter;
In a control device including a protection device that operates a power piston in a direction to close a turbine valve when a failure occurs in a position control loop, the protection device compares a control deviation with a certain limit value and determines when this limit value is reached. the position of the turbine valve operating part, characterized in that the power piston is operated in the closing direction of the turbine valve, and the limit value is changeable in relation to the temporal behavior of at least one disturbance amount interfering with the position control loop; Control device. 2. In the control device according to claim 1, a first limit value portion whose limit value can be set constant and at least one limit value portion derived from the temporal behavior of the amount of disturbance that interferes with the position control loop. 11. A turbine valve operating part position control device, characterized in that it is combined with another limit value part. 3) In the control device according to claim 2, a disturbance amount monitoring device is provided to form the limit value portion on the side, and a differential element or a dynamic element with similar behavior is provided after the device. A turbine valve operation part position control device, characterized in that: 4) The control device according to claim 3, wherein a first-order or higher-order time element is connected after the differential element. 5) The control device according to claim 3, wherein a differential element having temporal behavior is connected after the disturbance amount monitoring device. 6) The control device according to claim 5, wherein an absolute value forming circuit is connected after the differential element having temporal behavior. 7) The control device according to claim 6, characterized in that an asymmetric smoothing circuit is connected after the absolute value forming circuit. 8) In the control device according to claim 1, the limit value is composed of a first limit value portion that can be set to a constant value and a second limit value portion derived from the temporal behavior of the target value signal. A turbine valve operating part position control device characterized by being combined. 9) In the control device R4 according to claim 1,
A first limit value portion whose limit value can be set constant, a second limit value portion derived from the temporal behavior of the target value signal, and a third limit value portion derived from the temporal behavior of the pressure of the fluid supply. 1. A turbine valve operating section position control device, characterized in that it is combined with a limit value section. 10) In the control device according to claim 8 or 9, there is provided a first differentiating circuit having a temporal behavior and fed with a setpoint value signal for forming the second limit value part. A turbine valve operation part position control device characterized in that: 11) The control device according to claim 10, characterized in that a first absolute value forming circuit is connected after the first differential circuit having temporal behavior. Device. 12. The control device according to claim 11, characterized in that a first asymmetric smoothing circuit is connected after the first absolute value forming circuit. 13) In the control device according to claim 9,
Turbine valve actuator position control device, characterized in that a second differential element with time behavior is connected after the pressure monitoring device for the pressure of the fluid supply to form the third limit value part. 14) The control device according to claim 13, characterized in that a second absolute value forming circuit is connected after the second differential element having temporal behavior. Device. 15) A control device according to claim 14, characterized in that a second asymmetric smoothing circuit is connected after the second absolute value forming circuit.