JP2005105912A - Multi-coil servo valve controller - Google Patents

Abstract

Switching for returning a failure control system of a multi-coil servo valve during operation is performed without impairing the stable operation of the multi-coil servo valve.
A plurality of controllers 31 to 33 that respectively generate control command values for drive currents of a plurality of servo coils that drive a servo valve, a control command value output from each controller, and a servo valve position detection feedback value 27 In a control apparatus for a multi-coil servo valve having a multiple control system composed of a plurality of servo amplifiers 18 to 20 for controlling the drive current of each servo coil based on the difference between them, a bumpless return means is provided at the output stage of each controller. 63, the bumpless return means 63 receives the control command value 26a and the servo valve position detection feedback value 27 as input, and the failure of its own control system is recovered and the return command 55 to the multiple control system is input. When the return command is input, the servo valve position detection feedback value 27 is gradually set as an initial value to gradually control the control command value 26a. And outputting a changing value.
[Selection] Figure 1

Description

  The present invention relates to a controller for a multiple coil servo valve.

  Servo valves that control main equipment (such as turbines) in thermal power generation and nuclear power generation plants are required to have high reliability. Therefore, servo valves that drive and control servo valves with multiple servo coils are known. Yes. For example, a 3-coil servo valve is provided with a controller corresponding to each servo coil, the output of each controller is output to each servo coil via a servo amplifier, and the servo valve is driven and controlled by the total ampere turn of each coil. doing. According to such a triple control system, even if a failure occurs in one system of the controller, servo amplifier, and coil, the continuation of operation can be compensated by the remaining two normal systems.

  However, there is a possibility of further failure in the remaining two normal systems, so it is desirable to quickly stop the plant and restore the failed system, but stop the plant operation or reduce the load (load drop). The accompanying restoration work may not be acceptable due to the importance of the plant. In such a case, the faulty system will be repaired while continuing operation of the plant and the control will be restored to the control of the three systems. It is necessary not to give. That is, if the drive current from the restored controller is suddenly added to the drive current supplied to the servo coil before restoration, the opening of the servo valve increases, for example, and the operation of the plant fluctuates.

  Therefore, it is proposed to provide a tie-back (signal tracking) means that matches the output of the setting device of each controller at the time of restoration, and to set the setting value of the controller to be restored to the average value of the remaining two systems. (For example, Patent Document 1). In other words, if the servo valves controlled by two sound systems are controlled to a predetermined position, the control system for restoration is usually considered in view of the fact that the average value of the set values of these two systems is zero. The driving current is started from zero.

JP-A-6-346704

  However, according to the technique described in Patent Document 1, the setting value of the control system for recovery is switched from the average value of the sound setting values of the two systems to the original setting value when a predetermined time elapses. Yes. As a result, if there is a difference between the average value of the sound setting values of the two systems at the time of switching and the independent setting value of the control system related to restoration, the drive current of the servo coil suddenly changes and the three-coil servo valve opens. The degree may vary.

  It is an object of the present invention to perform switching for returning a failure control system of a multiple coil servo valve during operation without impairing the stable operation of the multiple coil servo valve.

  In order to solve the above problems, the present invention provides a plurality of controllers that respectively generate control command values for drive currents of a plurality of servo coils that drive servo valves, a control command value output from each controller, and the servo In a control apparatus for a multi-coil servo valve having a multiple control system composed of a plurality of servo amplifiers for controlling the drive current of each servo coil based on a difference from a valve position detection feedback value, an output stage of each controller A bumpless return means is provided, and the bumpless return means receives the control command value and the servo valve position detection feedback value as input, and recovers from the failure of its own control system and issues a return command to the multiple control system. When the return command is input, the servo valve position detection feedback value when the return command is input is gradually set to the control command value as an initial value. And outputs the value to reduction.

  In other words, the servo valve position detection feedback value is output as the initial value of the control command value from the controller related to the return by the bumpless return means at the beginning of the return. As a result, the difference between the control command value input to the servo amplifier and the servo valve position detection feedback value becomes zero, and no drive current is supplied from the servo amplifier to the servo coil, so that the same state as before the return can be maintained. Next, a control command value that gradually changes to the input control command value is output. As a result, the drive current supplied from the servo amplifier to the servo coil increases in response to the increase, and the control of the controller related to recovery starts to work. Without being affected, it is incorporated into the multiple control system by so-called bumpless. As the control system of the controller for recovery starts to work, the other healthy control system gradually reduces the drive current supplied to its own servo coil and stably shifts to the normal multiplex system.

  In the above case, the bumpless return means can change at a constant rate from the initial value to the control command value. The control command value can include a bias current (null bias current) that balances the mechanical reaction force of the servo valve.

  The switching for returning the failure control system of the multiple coil servo valve during operation can be performed without impairing the stable operation of the multiple coil servo valve.

  Embodiments of the present invention will be described below. FIG. 1 shows a block diagram of an embodiment relating to a bumpless return means of a characteristic part of the present invention, and FIG. 2 is an overall block diagram of a gas turbine system to which a three-coil servo valve of the present invention is applied. FIG. 4 shows an overall configuration diagram of a control apparatus for a three-coil servo valve according to an embodiment of the present invention.

  As shown in FIG. 2, the gas turbine system combusts the fuel supplied by the fuel pump 1 and the high-pressure air compressed by the compressor 2 in the combustor 3, and generates high-temperature and high-pressure gas. The gas turbine 4 is rotated at high speed by energy, and the generator 5 connected to the turbine 4 is driven to supply electric energy. The output energy of the gas turbine 4 is determined by the fuel flow rate, and the fuel flow rate can be controlled by a three-coil servo valve 6 that controls the bypass amount of the fuel pump 1.

  The control device for the three-coil servo valve 6 is configured as shown in FIGS. As shown in FIG. 3, the actuator 11 of the three-coil servo valve 6 is hydraulically driven via a hydraulic servo valve 13 through a hydraulic cylinder 12 that directly drives the valve body. The hydraulic servo valve 13 is controlled by a torque motor 17 having three servo coils 14, 15 and 16. The drive currents (servo currents) of the servo coils 14, 15, 16 are supplied from the servo amplifiers 18, 19, 20 via switches 21, 22, 23, respectively. Each servo amplifier 18, 19, 20 has a difference obtained by subtracting a servo valve position detection feedback value 27 output from a servo valve position detection feedback circuit 24 from a control command value 26 output from a controller described later by a subtracter 25. Each servo current is controlled based on. The servo valve position detection feedback circuit 24 takes in a position detection signal that is a control amount of the hydraulic cylinder 12 and outputs a servo valve position detection feedback value 27.

  The control command values 26 relating to the servo amplifiers 18, 19, and 20 are generated by the corresponding A-system, B-system, and C-system controllers 31, 32, and 33, respectively. The illustrations of the C-system controllers 32 and 33 are omitted. Since the A system, B system, and C system controllers 31, 32, and 33 have the same functional configuration, the A system controller 31 will be described.

  The A-system controller 31 receives detection signals from the speed sensor 34 and the exhaust temperature sensor 35, compares them with the respective speed setting value 36 and the exhaust temperature setting value 37, and sets the speed so that these detection signals become the setting values. Control is performed by a load control system 38 and an exhaust temperature control system 39. Control signals of the speed / load control system 38 and the exhaust temperature control system 39 are input to the control signal selector 43. In addition, an important signal 40 at the time of start, stop, and security is input to the sequence controller 41 in the A controller 31. The control signal of the sequence control system 41 is input to the control signal selection unit 43 together with the control signal of the activation control system 42. The control signal selector 43 selects the control signal having the smallest value among the input control signals and outputs the selected control signal to the control command value calculator 44. The control command value calculator 44 calculates the control command value 26 based on the input control signal and outputs it to the subtracter 25 in FIG. Control signals that are not selected by the control signal selector 43 are held as backup signals for the control command value 26.

  FIG. 5 shows a flowchart relating to the selection process of the control signal selection unit 43. First, the gas turbine is started by a start command (S1). Next, the command value 45 by the start control is selected as the control command value 26 until the speed reaches a certain speed that can be rotated by itself (S2). At this time, since the speed does not reach the set value, the command value 46 by the speed / load control is larger than the command value 45 by the start control. Similarly, since the exhaust gas temperature has not reached the set value (S3), the command value 47 by the exhaust gas temperature control is larger than the command value 46 by the speed / load control and the command value 45 by the start control. For this reason, in the control signal selection unit 43 that selects the minimum signal, the command value 45 by the start control is selected as the control command value 26. Next, when the gas turbine reaches its own rotational speed, the set value is reached, and the command value 46 by speed / load control is selected. The command value 45 by the start control at this time is set to a value higher than the command value 46 by the speed / load control value. Further, when the exhaust gas temperature becomes higher than the set value, the command value 47 is selected as the control command value 26. The control command value 26 selected in this way is input to the servo amplifier 18 via the control command value calculation unit 44 and the subtracter 25.

  Further, the A-system controller 31 has an abnormality detection function 50. The abnormality detection function 50 includes a controller abnormality detection function 51, a servo coil current feedback value diagnosis function 52, and a servo position feedback value diagnosis function 53. The controller abnormality detection function 51 is a CPU abnormality diagnosis function that detects an abnormality of the controller itself. The servo coil current feedback value diagnosis function 52 compares the control command value 26 of the controller with the feedback value 28 of the servo coil current to diagnose an abnormality in the servo coil 14 or the servo amplifier 18. The servo coil abnormality is, for example, when the servo coil is disconnected, and the feedback value 28 of the coil current at this time is zero. Further, when the servo amplifier 18 fails, the coil current feedback value 28 becomes a saturation current value. The servo position feedback value diagnosis function 53 compares the control command value 26 with the servo valve position detection feedback value 27 to diagnose an abnormality of the servo position detector. When abnormal, the control command value 26 and the servo valve position detection feedback value 27 are different from each other. With this abnormality detection function 50, the A controller 31 can diagnose abnormality of each component in the control system, for example, controller abnormality, servo amplifier abnormality, servo coil abnormality, and servo position detection abnormality. When an abnormality is found, the switch 21 provided on the output side of the servo amplifier is opened to disconnect the A-system control. The B-system and C-system controllers 32 and 33 are similarly configured.

  Next, the configuration of the bumpless return means provided at the output stage of the control command calculation unit 44 according to the characteristic part of the present invention will be described with reference to FIG. The control command calculation unit 44 generates a control command value 26 a based on the control signal output from the control signal selection unit 43, and uses the null bias value (for example, 0.6 mA) output from the null bias setting unit 62 in the adder 61. The value is added and input to the input end X1 of the bumpless return means 63 provided at the output stage as the control command value 26b. A servo valve position detection feedback value 27 is input to the input end X2 of the bumpless return means 63. The bumpless recovery means 63 is configured so that the abnormality detection function 50 restores the A system controller, which is its own control system, from the failure state, and inputs a return command 55 to the multiple control system.

  The bumpless return means 63 is constituted by a calculation means by a program similar to the control command calculation unit 44. During normal operation, the bumpless return means 63 simply passes the control command value 26 added with the null bias value and outputs it to the subtracter 25. It is supposed to be. The null bias value is a drive current for balancing with the mechanical reaction force of the servo valve, and is 0.6 mA, for example. On the other hand, when a return command 55 for returning to the multiple control system is input, the bumpless return means 63 gradually responds to the return command 55 and uses the servo valve position detection feedback value 27 as an initial value to gradually control the control command value 26b. And is output to the subtracter 25. The rate of gradually changing can be set to a constant rate of, for example, 0.05% / second, but this can be appropriately set to an arbitrary rate of change according to the response of the 3-coil servo control system. it can. A servo valve position detection feedback value 27 is input as a negative feedback value to the subtracter 25, and a difference between the control command value 26 b and the servo valve position detection feedback value 27 is input to the servo amplifier 18. The servo current that is the output of the servo amplifier 18 is supplied to the servo coil 14 via the switch 21. The switch 21 is turned on by a return command 55 described later.

  The operation of the bumpless return means configured as described above will be described in comparison with the conventional method. FIG. 6 shows a term chart at the time of return of the fault control system according to the conventional method, and FIG. 7 shows a term chart at the time of return of the fault control system according to the present invention. In FIG. 6, (a), (b), and (c) are servo currents output from the A-system, B-system, and C-system servo amplifiers 18 to 20, respectively, and FIG. In total, (e) indicates the fuel flow rate, and (e) indicates the exhaust temperature. The horizontal axis is time. If an abnormality occurs in the A-system controller 31 at time t1, the A-system servo current becomes 0 mA. After that, the A system controller 31 is turned off, the cause of the abnormality is investigated and repaired when the cause is found, and then the power is turned on to output a return command 55 for restarting the A system controller 31 at t2. As a result, the A-system servo current starts to flow instantaneously.

  That is, when an abnormality occurs in the A-system controller 31, the abnormality detection function 50 of the A-system controller 31 operates, the switch 21 opens, and the A-system servo supplied from the servo amplifier 18 to the servo coil 14 is detected. The current becomes 0 mA. When the servo current of the A system becomes 0 mA, the total servo current decreases from 1.8 mA to 1.2 mA. Therefore, the torque of the torque motor 17 is weakened, and the three-coil servo valve 6 operates in the closing direction to reduce the fuel. . At the same time, since the servo valve position detection feedback value 27 is lowered, the total current of the B servo amplifier 19 and the C servo amplifier 20 is increased to 1.8 mA which is the same as the total servo current that has been flowing so far. At that point, the control becomes stable.

  After that, after the contents of the abnormality are found and repaired, the case where the Λ-system controller 31 is restored while continuing the plant operation state and incorporated into the triple control system will be described. If the A-system controller 31 is restored at t2 in the figure, the switch 21 is closed with the restart. At this time, the servo current of the same value as that of the other normal B-system and C-system servo amplifiers 19 and 20 is instantaneously supplied from the A-system servo amplifier 18, and the total servo current suddenly changes to 2.7 mA. . Therefore, the force of the torque motor 17 is increased, the three-coil servo valve 6 operates rapidly in the opening direction, the fuel flow rate increases rapidly, and the exhaust temperature also increases. When this temperature rise value reaches a trip value that seriously affects the thermal stress of the gas turbine 4, a gas turbine plant trip (plant trip) is reached. When the operation state of the gas turbine 4 is rated load operation, the exhaust temperature is usually operated with a certain temperature difference (for example, 22 ° C.) up to the trip value. If it is restored, it will lead to a plant trip. For example, when the exhaust temperature trip value is 585 ° C. and the rated load operation is performed at 563 ° C., if the controller is restarted and the temperature rises to 590 ° C., a trip occurs. Note that the increase in exhaust temperature (servo current increase) when the controller is restored decreases as the gas turbine load (plant load) decreases. It does not increase to the trip value.

  The present invention suppresses a sudden change in the servo current at the time of controller return even during rated load operation, for example, to suppress an increase in exhaust temperature, so that the servo current from the restored controller is not changed suddenly at the time of return. A bumpless return means 63 that gradually flows is added to the output stage of the controller. The operation of the bumpless return means 63 will be described with reference to the configuration diagram of FIG. 1 and the term chart of FIG. In FIG. 7, (a) is the output of the bumpless return means 63, (b), (c), and (d) are servo currents output from the A-system, B-system, and C-system servo amplifiers 18 to 20, respectively. (E) shows the sum of the servo currents, (f) shows the fuel flow rate, and (g) shows the exhaust temperature. The horizontal axis is time.

  When the return signal 55 changes from OFF to ON, the bumpless return means 63 uses the control command value 26b (output Y) as the initial value and the servo valve position detection feedback value 27 (X2) as the initial control. The command value 26a (X1) has a function of gradually switching to the value of the command value 26a (X1) at a constant rate (for example, 0.05% / s), that is, bumpless. For example, the return signal 55 is output from the abnormality detection means 50 as an initial completion signal of the controller. Before restoration of the controller, the return signal 55 is OFF. In this case, the output Y of the bumpless return means 63 outputs the same value as the servo valve position detection feedback value. When the restoration operation of the controller is performed and the return signal 55 is turned ON when the initial operation is completed inside the controller, the output Y is gradually switched to the value of the control command value 26a.

As a result, the servo current output from the servo amplifier 18 is as follows.
(1) Servo current before and after return = (Servo valve position detection feedback value 27)
-(Servo valve position detection feedback value 27)
= 0mA
(2) Servo current during return = (control command value 26b)-(servo valve position detection feedback value 27)
= Value that gradually changes at a constant rate (3) Servo current at completion of return = (Control command value 26b)-(Servo valve position detection feedback value 27)
The servo current at the completion of the return is actually a null bias current of 0.6 mA because the control of the three systems of controllers should be balanced. When the A system controller 31 becomes abnormal, the control command values 26b of the B system controller 32 and the C system controller 33 are higher than values before the A system controller 31 becomes abnormal. This is because the control command calculation circuit 44 increases the control command value 26a because it has been necessary to control only the remaining two coils from the state in which the control was performed with three coils.

  The servo current from the A-system controller 31 starts from 0 mA and changes until the same value as the servo currents of the B-system controller 32 and the C-system controller 33 at a constant rate by the function of the bumpless return means 63 described above. . Then, when the A system servo current increases, the B system and C system servo currents decrease, and as a result, the total current is controlled to be constant. Therefore, the fuel flow rate does not change, the exhaust temperature does not change, and the recovery work can be performed even during rated load operation.

  As described above, according to the present embodiment, in the three-coil servo valve control controlled by the triple controllers 31, 32, 33, even when the plant is operated at the rated load, Restoration work is possible, and there is an effect that it is possible to avoid the restrictions (plant stop, plant load drop) in the restoration work.

It is a block diagram of one embodiment of the bumpless return means and the peripheral part according to the characteristic part of the present invention. 1 is an overall configuration diagram of a gas turbine plant according to an embodiment to which a three-coil servo valve according to the present invention is applied. It is a block diagram of one embodiment around the servo valve of the three-coil servo valve control device according to the present invention. It is a block diagram of one Embodiment around the controller of the 3 coil servo valve control apparatus which concerns on this invention. FIG. 5 is a flowchart according to the selection process of the control signal selection unit of the embodiment. It is a term chart explaining the change of the electric current etc. of each part at the time of return of the failure control system by a conventional method. It is a term chart explaining the change of the electric current etc. of each part at the time of return of the failure control system by this invention. It is a figure which shows the structure of the 3 coil servo valve control apparatus which concerns on one Example of this invention.

Explanation of symbols

18 Servo amplifier 21 Switch 25 Subtractor 26a, 26b Control command value 27 Servo valve position detection feedback value 44 Control command value calculator 55 Return command 61 Adder 62 Null bias setting device 63 Bumpless return means

Claims (3)

A plurality of controllers that respectively generate control command values for a plurality of servo coils that drive the servo valves, and each servo coil based on a difference between the control command value output from each controller and a servo valve position detection feedback value In a control apparatus for a multiple coil servo valve having a multiple control system composed of a plurality of servo amplifiers that respectively control the drive current of
A bumpless return means is provided at the output stage of each controller, and the bumpless return means receives the control command value and the servo valve position detection feedback value as input, and recovers from the failure of its own control system. When a return command is input to the control system, a value that gradually changes to the control command value is output using the servo valve position detection feedback value at the time of input of the return command as an initial value. Servo valve control device.   2. The multi-coil servo valve control device according to claim 1, wherein the bumpless return means changes at a constant rate from the initial value to the control command value.   The multi-coil servo valve control device according to claim 1, wherein the control command value includes a bias current that balances a mechanical reaction force of the servo valve.

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