JP4688840B2 - Multi-coil servo valve controller - Google Patents

Description

  The present invention relates to a control apparatus for a multiple coil servo valve, and more particularly to a technique for controlling a three coil servo valve controlled by a triple controller.

  Servo valves that control major equipment (such as turbines) in thermal power plants and nuclear power plants require high reliability, so one servo valve is composed of multiple controllers and corresponding servo coils. There is known a method for controlling the driving of the motor (for example, Patent Document 1).

  The outputs of the controllers given to the servo valves driven by the three servo coils are output to the respective servo amplifiers as deviations between the servo valve control command value and the servo valve opening feedback value. . A total of one ampere turn of each servo coil to which the servo current as the output of each servo amplifier is supplied (the magnetomotive force of the electromagnet is expressed by the synergistic product of the current and the number of turns of the electric wire. The servo valve is driven. Then, the servo valve is controlled so that the deviation between the control command value of the servo valve and the opening feedback value of the servo valve is balanced at a position where it becomes 0 mA. Actually, at 0 mA, the servo valve moves in the closing direction, so that a balance is provided by giving a null bias value of 0.6 mA.

  The invention described in Patent Document 1 that the inventor has already proposed is a case where an abnormality occurs in one of the three controllers (for example, the A system controller) and the control command value of the controller falls to 0 mA. The problem was to restore the abnormal controller. That is, before the abnormality of the A-system controller, the servo current output from each controller was 0.6 mA, and the total of the currents supplied to the three servo coils was 1.8 mA, and the balance was maintained.

  In this state, since the control command value from the A system controller becomes 0 mA, the control command values (servo currents) of the B system and the C system controller increase in the direction in which the opening degree of the servo valve is maintained. That is, the control command value from the B system controller and the C system controller is increased to 0.9 mA so that the total becomes 1.8 mA. The invention described in Patent Document 1 proposes a three-coil servo valve control device that can recover the abnormality of the A-system controller in this case without causing any trouble in plant operation.

  That is, the invention described in Patent Document 1 is provided with a bumpless return means at the output stage of each controller, and the control command value of the servo coil drive current and the servo valve position detection feedback value (open) as the input of the bumpless return means. Same as feedback value). When the failure of its own control system is recovered and a multiple control system return command is input, the servo valve position detection feedback value at the time of input of the return command is used as an initial value, and the servo coil drive current is gradually increased. A value that changes to 0.6 mA, which is the control command value, is output.

JP 2005-105912 A

  However, the technique described in Patent Document 1 assumes a case where the servo current from the A-system servo amplifier becomes 0 mA due to an abnormality of the A-system controller. For example, it is not assumed that the output value from the A-system servo amplifier suddenly changes to an extremely high value due to an abnormality (failure) in the opening sensor.

  Details will be described later with reference to FIGS. 8 and 9, but in the triple control servo valve control device, when one of the two opening sensors (LVDT-1) fails, The control command value from the A-system controller to which only the opening feedback value from this one opening sensor is supplied rises rapidly to 9 mA or more. If the opening sensor (LVDT-1) is to be restored after a lapse of a predetermined time, the output of the A system controller, which has output 9 mA or more, is once the output value of the B system and C system controller- The value rapidly decreases to 3.6 mA, and then increases to 0.6 mA at which the servo valve opening is stabilized. Correspondingly, the output values of the B-system and C-system controllers change from -3.6 mA to 0.6 mA. In this way, the three servo coils have the same current and can be balanced. However, when the opening sensor is restored, a phenomenon of dropping to −10.8 mA as shown in FIG. 9 occurs. In this state, there is a possibility that the servo valve is completely closed, that is, a fully closed state, and a circuit for preventing this is required.

  An object of the present invention is to solve the above-mentioned problem by performing recovery during operation when one of the two opening sensors has failed, without impairing the stable operation of the servo valve by a plurality of coils. Is to do so.

In order to solve the above-described problems and achieve the object of the present invention, a multiple-coil servo valve control device having a multiple control system according to the present invention includes a plurality of control command values for a plurality of servo coils that drive a servo valve. A controller, a plurality of opening sensors that detect the opening of the servo valve, and a servo valve position detection feedback circuit that detects the position of the servo valve based on the output of the opening sensor. Further, based on the difference between the control command value output from each of the plurality of controllers and the servo valve position detection feedback value output from the servo valve position detection feedback circuit, the servo current for driving the plurality of servo coils is respectively determined. It has multiple servo amplifiers to control.
A bumpless return means is provided at each output stage of the plurality of controllers, and a control command value and a servo valve position detection feedback value are input to the bumpless return means. When an abnormality occurs in one of the plurality of opening sensors, each of the bumpless return means of the plurality of controllers uses a control command value as an initial value and a constant rate from the control command value to the servo valve position detection feedback value. A control signal that changes at is output. Then, the controller to which only the opening sensor in which an abnormality has occurred is connected controls the servo valve so that the servo current supplied to the servo coil connected to this controller gradually becomes zero.

  That is, from the controller to which only the failed opening sensor is connected, the control command value is output as it is as the initial value by the bumpless return means when the failure occurs. That is, the difference between the control command value input to the servo amplifier and the servo valve position detection feedback value (opening signal = 0 mA) is supplied from the bumpless return means to the servo coil as an initial value.

  Next, the input control command value gradually increases toward the servo valve position detection feedback value. As a result, the servo current supplied from the servo amplifier to the servo coil approaches zero, and the control system of the controller related to the return does not cause disturbance such as sudden change. That is, the output of the bumpless return means gradually becomes zero. As the control system of the controller related to recovery starts working, other healthy control systems can gradually increase the servo current supplied to their own servo coils and stably shift to the normal multiplexing system. .

  In the above case, as a preferred mode, the bumpless return means changes the initial value (control command value) to the servo valve position detection feedback value at a constant rate. Further, as a result, the opening degree sensor can be replaced without changing the plant output. Then, after replacing the opening sensor, the servo valve position detection feedback value is changed to the control command value as an initial value in reverse to the above, and the abnormal operation is caused by the failure of the opening sensor while continuing the operation of the plant. It is possible to smoothly restore the controller that has been used.

  According to the present invention, it is possible to restore the failed opening degree sensor while the three-coil servo valve control device is in operation. That is, the controller output related to the failed opening sensor can be gradually switched to 0 mA (without sudden change) without impairing the stable operation of the multi-coil servovalve. In addition, after the opening degree sensor is restored, an operation for adjusting the output of the controller to the output of another controller can be performed by the reverse operation described above.

  Hereinafter, an exemplary embodiment of the present invention (hereinafter referred to as “this example”) will be described with reference to FIGS. The present embodiment is characterized in that a bumpless return means 63 is provided at the rear stage of each controller, and the operation from the failure of the opening sensor to its recovery is smoothly performed.

FIG. 1 is a configuration diagram of an embodiment according to a bumpless return means of a feature of the present invention. FIG. 2 is an overall configuration diagram of a gas turbine system to which the three-coil servo valve of the present invention is applied.
Further, FIG. 3 is an overall configuration diagram of a three-coil servo valve control device according to an embodiment of the present invention, and FIG. 4 is a schematic configuration diagram of a controller connected to the three-coil servo valve control circuit of FIG. It is shown. FIG. 5 is a flowchart for explaining the operation of the gas turbine. FIG. 6 is an overall configuration diagram of a three-coil servo current control device to which the present invention is applied, and FIG. 7 explains an operation at the time of recovery from an opening sensor failure of the three-coil servo current control device shown in FIG. FIG.

  First, as shown in FIG. 2, the gas turbine system mixes the fuel supplied by the fuel pump 1 and the high-pressure air compressed by the compressor 2, and burns this mixed gas in the combustor 3. Generate high temperature and pressure gas. Then, the gas turbine 4 is rotated at a high speed by the high-temperature high-pressure gas, and the generator 5 connected to the gas turbine 4 is driven to generate electric energy. The output energy of the gas turbine 4 is determined by the fuel flow rate, and this fuel flow rate is controlled by a three-coil servo valve 6 that controls the bypass amount of the fuel pump 1. The starter motor 7 is a motor used when starting the gas turbine 4.

  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 (see FIG. 2) hydraulically drives the hydraulic cylinder 12 that directly drives the valve body via the hydraulic servo valve 13. 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.

  A control command value 26b output from each controller, which will be described later, is added to a subtractor 25, where a servo valve position feedback value 27, which is an output of the servo valve position detection feedback circuit 24, is subtracted from the control command value 26b. . The subtraction result of the subtracter 25 is supplied as a control command value 26 to the servo coils 14, 15, 16 via the servo amplifiers 18, 19, 20, and the respective servo currents are controlled. The servo valve position detection feedback circuit 24 takes in a position detection signal corresponding to the control amount of the hydraulic cylinder 12 detected by the opening sensor 70 and outputs it as a servo valve position detection feedback value 27.

  The servo valve position detection feedback value 27 is applied to one switching terminal of a switch constituting a bumpless return means 63, which will be described in detail later. A control command value 26a 'from the controller is supplied to the other switching terminal of the switch. The switch switching control is performed by a return command 55 described later.

  Next, the operation of each controller will be described with reference to FIG. As shown in FIG. 4, the control command value 26b supplied to the subtracter 25 of FIG. 3 is generated by the corresponding controllers A, B, and C of the systems 31, 32, and 33, respectively. 4, the illustration of the B-system and C-system controllers 32 and 33 is omitted. Since each of the A-system, B-system, and C-system controllers 31, 32, and 33 has the same functional configuration, only the A-system controller 31 will be described here.

Detection signals from the speed sensor 34 and the exhaust temperature sensor 35 are input to the A-system controller 31 and compared with the speed set value 36 and the exhaust temperature set value 37, respectively.
Then, the speed / load control system 38 and the exhaust temperature control system 39 are controlled so that these detection signals coincide with the set values.

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 26b based on the input control signal and outputs it to the subtracter 25 in FIG. The control signal not selected by the control signal selection unit 43 is held as a backup signal for the control command value 26b.

  Next, the abnormality detection function of the A-system controller 31 will be described. The A-system controller 31 in FIG. 4 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 valve 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 26b 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 abnormality of the servo coil is, for example, when the servo coil is disconnected, and the feedback value 28 of the coil current at this time is “0”. Further, when the servo amplifier 18 fails, the coil current feedback value 28 becomes a saturation current value.

  The servo valve position feedback value diagnosis function 53 compares the control command value 26b with the servo valve position detection feedback value 27 to diagnose an abnormality in servo valve position detection. When abnormal, the control command value 26b and the servo valve position detection feedback value 27 are different from each other. With the abnormality detection function 50 described above, the A-system 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. If an abnormality is found in these parts, the switch 21 (see FIG. 3) provided on the output side of the servo amplifier is opened to disconnect the control of the A-system controller from the servo coil. The B-system and C-system controllers 32 and 33 are similarly configured.

  Next, the operation of the three-coil servo current control device of this example will be described based on the flowchart of FIG. First, the gas turbine 4 is activated by the rotation of the activation motor 7 according to the activation command (step S1). Next, it is determined whether or not the rotation of the gas turbine 4 has reached a certain speed or higher that allows the gas turbine 4 to rotate by itself (step S2). When it is determined in this determination step S2 that the gas turbine speed has not reached the predetermined value, the command value 45 by the start control is selected as the control command value 26a shown in FIG. At this time, the command value 45 by the start control is smaller than the command value 46 by the speed / load control.

  If it is determined in the determination step S2 that the speed of the gas turbine is equal to or higher than a certain value, it is subsequently determined whether or not the exhaust temperature is higher than a set value (step S3). When it is determined in this determination step S3 that the exhaust gas temperature has not reached the set value, the command value 46 by speed / load control is selected as the control command value 26a. The command value 46 by the speed / load control is smaller than the command value 45 by the start control. Similarly, since the exhaust temperature has not reached the set value, the command value 47 by the exhaust temperature control is larger than the command value 46 by the speed load control.

  If it is determined in the determination step S3 that the exhaust gas temperature is equal to or higher than the set value, the command value 47 by the exhaust gas temperature control is selected as the control command value 26a. When the exhaust gas temperature becomes equal to or higher than the set value, the command value 47 based on the exhaust gas temperature becomes smaller than the command value 46 based on the speed / load control. In this case, the command value 47 based on the exhaust gas temperature is selected as the control command value 26a. . The control command value 26a selected in this way is input to the servo amplifier 18 through processing by the control command value calculation unit 44 and the subtracter 25.

  Next, the configuration and operation of the bumpless return means 63 provided at the output stage of the control command calculation unit 44 according to the feature of the present invention will be described with reference to FIG. As described above, the control command calculation unit 44 generates the control command value 26 a based on the control signal output from the control signal selection unit 43, and this control command value 26 a is output from the null bias setting device 62 in the adder 61. Is added to the null bias value.

The output of the adder 61 is input as the control command value 26a ′ to the input terminal X1 of the bumpless return means 63 provided in the output stage of the control command calculation unit 44. 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 supplied with an abnormality detection signal from the abnormality detection function 50 shown in FIG. 4 via an OR circuit 64 and a knot circuit 65, whereby an A system that is its own control system. The controller recovers from the failure state, and a return command 55 to the multiple control system is input.

  Further, in this example, in addition to the abnormality detection signal from the abnormality detection function 50, a “single opening sensor failure signal” 70 is sent as a return command 55 via the OR circuit 64 and the knot circuit 65 as a bumpless return means. 63.

  Here, the bumpless return means 63 is constituted by a calculation means based on a program. During normal operation, the bumpless return means 63 simply passes the control command value 26a ′ added with the null bias value and outputs it to the subtracter 25. ing. 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 the opening sensor 70 breaks down and then a predetermined time has elapsed (sufficient time until it stabilizes at 9 mA after the occurrence of time t1 in FIG. 7), when the failure signal becomes “ON”, the multiple control system is restored. The return command 55 becomes “OFF”, and the bumpless return means 63 gradually changes to the servo valve position detection feedback value 27 supplied to the input X2 with the control command value 26a ′ supplied to the input X1 as an initial value. The control command value 26b to be output is output to the subtracter 25. (Time t2 in FIG. 7)
Thereafter, when the failure of the opening sensor 70 is restored, the return command 55 is switched from “OFF” to “ON” by turning the “one opening sensor failure signal” 70 “OFF”, and the bumpless return The means 63 starts to return to the input X1.

  In this bumpless return means 63, the rate of gradually changing the bumpless switching circuit output as shown in FIG. 7 is set to a constant rate of 0.05% / second as an example here. Depending on the response of the 3-coil servo control system, an arbitrary change rate can be set as appropriate.

  The control command value 26b, which is the output of the bumpless return means 63, is supplied to the subtractor 25, and the servo valve position detection feedback value 27 is input to the subtracter 25 as a negative feedback value. Therefore, the difference between the control command value 26 b and the servo valve position detection feedback value 27 is input to the servo amplifier 18 as the control command value 26. The servo current that is the output of the servo amplifier 18 is supplied to the servo coil 14 via the switch 21.

In the embodiment of the present invention, as shown in FIG. 1, a control command value 26 a ′ obtained by adding a null bias value to the control command value 26 a given from the control command selection unit 43 is subtracted via a bumpless return means 63. 25. This is to make the servo current from the controller zero before restoring the opening sensor so that the restoration of the opening sensor does not lead to a sudden change in the servo current.
That is, the bumpless return means 63 is means for gradually decreasing the servo current of the controller that has risen without suddenly changing the servo current from the controller to which the failed opening degree sensor is connected. By adding the bumpless return means 63 to the output stage of the controller, it is possible to realize the restoration of the failed opening degree sensor without stopping the operation of the plant.

  Next, the operation of the three-coil servo current control device when a failure of the opening sensor in this example is detected will be described. For comparison with this example, first, the present invention will be described based on FIG. 8 and FIG. An example of the occurrence of an abnormality in the three-coil servo valve control device that is not provided with the bumpless return means 63 (bumpless switching circuit) that is the main part of FIG.

FIG. 8 is a diagram for explaining a case where an abnormality occurs in one of the opening sensors used in the three-coil servo valve control device. In the triple control system as shown in FIG. 8, two opening sensors 70 for detecting the opening feedback value of the servo valve (same as the servo valve position detection feedback value) are provided.
Among these opening sensors, the output of the first opening sensor (LVDT-1) is supplied to the A system controller and the B system controller, and the output of the second opening sensor (LVDT-2) is B It is supplied to the system controller and the C system controller.

  In other words, the opening feedback value from the two opening sensors is supplied only to the B system controller, and in the B system controller, the larger one of these two opening feedback values is used as the opening feedback value. It has come to be.

  In such a three-coil servo valve control device, one of the two opening sensors 70 has now failed, and one system of the control system including the controller, servo amplifier and servo coil has output an abnormal value. Even in this case, the remaining two normal systems compensate for that amount, so that the operation can be continued. That is, even if an abnormality occurs in one controller, the servo valve can be stably controlled by the outputs of the other two controllers.

  For example, if the signal of the first opening sensor (LVDT-1) input to the A system controller 31 and the B system controller 32 is down (opening signal (opening feedback value) = zero), the A system The controller 31 erroneously recognizes that the opening degree signal has been lost as the opening degree of the servo valve has decreased, and outputs a large current to open the servo valve as described above. At this time, signals are applied to the B-system controller 32 from the two opening sensors, and the B-system controller 32 selects the high values of these two opening sensor outputs, so that one of the opening sensors is opened. Even if the degree sensor (LVDT-1) goes down, there is no special effect.

  When the control command value 26 from the A-system controller 31 to the servo amplifier 18 increases, the servo current from the servo amplifier 18 increases, so that the servo valve operates more in the opening direction. Here, the control command value 26 supplied to the servo amplifier 18 is a value obtained by subtracting the opening feedback value 27 from the control command value 26b which is an output value of the controller in the subtractor 25.

  As described above, when the control command value 26 to the servo amplifier 18 is increased, for example, the servo valve that has been operating steadily at the opening degree of 50% is further controlled in the opening direction. As a result, the opening degree feedback value from the second opening degree sensor (LVDT-2) becomes large, and this time, the opening degree feedback value for the B system controller 32 and the C system controller 33 becomes larger than the control command value 26b. .

  For this reason, as shown as servo current in FIG. 8, the B-system controller 32 and the C-system controller 33 flow a servo current in the opposite direction to that of the A-system controller 31. As a result, the control command value and the opening degree feedback Balance is made at a position where the deviation becomes “0”. This balance is balanced at a position where the opening is larger than the original opening of the servo valve.

In the three-coil servo valve control device as shown in FIG. 8, even if one of the opening sensors fails, the operation is continued although output fluctuation occurs. However, if the following condition occurs further from that state, the servo current suddenly changes, the fuel is excessively charged, the exhaust temperature becomes high, and the continuous operation becomes difficult. That is,
(1) When one of the servo modules of the A system, B system, and C system controller fails.
(2) When one of the A, B and C controllers fails.
(3) When one of the 3-coil servos is disconnected.
It is.

  For this reason, it is desirable to quickly stop the plant or the like to restore the faulty system, but there are cases where the restoration operation accompanied by the plant operation stop or load reduction (load drop) is not acceptable in view of the importance of the plant. In such a case, it is necessary to repair the broken opening sensor while continuing the operation of the plant. That is, even when the opening sensor is repaired, it is necessary to repair the opening sensor so as not to change the plant.

  FIG. 9 is a time chart (waveform diagram) for explaining the operation of the three-coil servo valve control device shown in FIG. Based on FIG. 9, the operation of the three-coil servo valve control device shown in FIG. 8 will be described in detail.

  9, (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. Total, (e) indicates the fuel valve opening. The horizontal axis is the time axis.

Now, assuming that one opening sensor (LVDT-1) has failed at time tl shown in FIG. 9, the servo valve position detection feedback value decreases at time t1 when the opening sensor abnormality occurs (FIG. 9). 8 opening signal = 0). As a result, the servo current supplied from the A-system controller 31 to the servo coil 14 via the servo amplifier 18 instantaneously becomes 9 mA or more. As described above, this is due to the fact that the A-system controller 31 erroneously recognizes that the opening degree signal has been lost, that the opening degree of the servo valve 13 (see FIG. 3) has decreased.
When the servo current of the A-system controller 31 becomes 9 mA or more, the total servo current of the three servo coils 14 to 16 increases from 1.8 mA to 10.2 mA or more as shown in FIG. The force (see FIG. 3) is strengthened and the three-coil servo valve 13 operates in the opening direction. For this reason, the problem that the fuel supplied from the fuel pump 1 (refer FIG. 2) increases rapidly will generate | occur | produce.

  At the same time, since the servo valve position detection feedback value 27 is increased, the total current of the B-system servo amplifier 19 and the C-system servo amplifier 20 is decreased (1.2 mA → −7.2 mA) and has flowed until then. The control is stabilized when the current becomes 1.8 mA which is the same as the total servo current. It stabilizes at a value of 1.8 mA obtained by adding the combined current of the B system and the C system of -7.2 mA and the servo current of the A system of 9 mA.

  From this state, when the failed first opening degree sensor (LVDT-1) is to be restored at time t2, the servo current from the A system controller 31 instantaneously causes the B system and C system controllers 32, 33. Starts to flow in the opposite direction so as to have the same value as the servo current of. As a result, the control command value from the B-system and C-system controllers 32 and 33 greatly fluctuates in the minus direction, and the total servo current of the three coils becomes −10.8 mA or more. This state is not preferable because the value exceeds the range of stable control of the servo valve 13. That is, when the total servo current of the three coils becomes a large negative current, the force of the torque motor 17 is weakened, and the three-coil servo valve 13 operates rapidly in the closing direction. As a result, since the fuel flow rate is rapidly reduced, the gas turbine 4 may become inoperative and a plant trip (a plant inoperative state) may occur.

  FIG. 6 shows an embodiment of the present invention that solves the above-described problems of the three-coil servo current control device shown in FIG. 8, and FIG. 7 is an operation waveform diagram thereof.

  In the three-coil servo valve control device shown in FIG. 6, a bumpless switching circuit (same as the “bumpless return means 63”) 63 that is operated when a single opening sensor is recovered from a failure is provided at the output stage of each controller. This is different from the apparatus shown in FIG. By providing the bumpless switching circuit 63, it is possible to perform the recovery operation after the failure of one opening sensor without affecting the operation of the plant.

  Only the A-system controller 31 will be described. As shown in FIG. 6, a servo valve control command value 26a 'is added to one terminal of the switch constituting the bumpless switching circuit 63, and this value is usually added as it is. Is supplied to the container 25. The servo valve position detection feedback value 27 from the opening sensor 70 is supplied to the other terminal of the switch of the bumpless switching circuit 63, and the servo current from the controller is supplied to repair the failed opening sensor 70. When the “one sensor opening sensor failure signal” 70 is turned ON for the purpose of 0 mA, the switching operation of this switch is performed at a predetermined rate, for example, a constant rate of 0.05% / second, from the control command value 26a ′ to the servo valve. The position detection feedback value 27 is switched.

  FIG. 7 is a waveform diagram showing the overall operation of the A-system, B-system, and C-system controllers including the operation of the bumpless switching circuit 63 shown in FIG. 6. The difference from FIG. Servo current output from the controller.

  FIG. 7A shows the output of the bumpless switching circuit 63, but the control command value 26a ′ (control command value 26a + null bias value) until the “one-unit opening sensor failure signal” 70 is turned ON. Is output. When the “one-unit opening sensor failure signal” 70 is turned ON at time t2, the output of the bumpless switching circuit 63 is a predetermined value from the control command value 26a ′ toward the feedback value 27 of the servo valve position detector. Controlled to move at rate.

  As a result, the servo current of the A-system controller 31 gradually decreases from 9 mA or more to 0 mA. In addition, the servo current output from the servo amplifiers 19 and 20 of the B system and C system controllers 32 and 33 gradually increases from −3.6 mA to 0.9 mA. As a result, the rated current of 1.8 mA can be achieved only by the servo current from the B system and C system controllers 32 and 33, and the servo current from the A system controller 31 can be maintained at 0 mA. In this state, after repairing one broken opening sensor, the A system controller 31 is returned to normal operation, and the 0.6 mA servo is supplied from each of the A system, B system, and C system controllers 31-33. The current is output and the rated operation is performed.

  7, (a) is the output of the bumpless return means 63, and (b), (c), and (d) are the outputs from the respective servo amplifiers 18 to 20 of the A system, B system, and C system controllers 31 to 33, respectively. (E) shows the sum of those servo currents, and (f) shows the opening of the fuel valve. The horizontal axis is the time axis.

  When the return signal 55 changes from ON to OFF, the bumpless return means 63 servos the control command value 26b (output Y) as the initial value and the control command value 26a ′ (X1) as the initial value. The valve position detection feedback value 27 (X2) is gradually switched at a constant rate (for example, 0.05% / s). "Bumpless" is a term that means this gradual switching. The return signal 55 is output as, for example, “an abnormality (failure) signal of one opening sensor”. For example, before the abnormality of one opening degree sensor (LVDT-1), the return signal 55 is ON. The output Y of the bumpless return means 63 in this case is a value 26a ′ (X1) obtained by adding the control command value 26a and the null bias value by the adder 61. Then, after the abnormality of the opening sensor (LVDT-1) occurs, when the servo current becomes stable and the "one opening sensor failure signal" 70 is turned ON and the return signal 55 is turned OFF, the bumpless return means 63 The output Y is gradually switched so as to approach the value of the servo valve position detection feedback value 27, that is, 0 mA.

As a result, the servo current of the A-system controller output from the servo amplifier 18 is as follows.
(1) Servo current before failure = (control command value 26a ′) − (servo valve position detection feedback value 27) = 0.6 mA
(2) Servo current at the time of failure = (control command value 26a ')-(servo valve position detection feedback value 27) = excessive current value in the + direction (9 mA or more)
(3) Servo current after failure occurrence = (control command value 26a ′) − (servo valve position detection feedback value 27) = (value gradually changing toward 0 mA at a constant rate)

As described above, due to the function of the bumpless return means 63, the servo current from the A-system controller 31 starts at 9 mA and changes until it reaches 0 mA at a constant rate.
Then, when the servo current of the A system decreases, the servo currents of the B system and the C system increase, and as a result, the total current is controlled to be constant. Therefore, there is no change in the opening of the fuel valve, and recovery work is possible even during rated load operation.

  As described above, according to the embodiment of the present invention, in the three-coil servo valve control controlled by the triple controllers 31, 32, 33, one control system is operated in a state where the plant is operated at the rated load. This makes it possible to perform a recovery work for the above-mentioned failure and to avoid the restrictions (plant stop, plant load drop) in the recovery 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 circuit explanatory drawing at the time of abnormality generation | occurrence | production in the 3 coil servo valve control apparatus which shows one embodiment of this invention. FIG. 7 is a time chart (waveform diagram) for explaining changes in currents and the like of respective parts when the failure control system is restored in the embodiment of the present invention shown in FIG. 6. It is circuit explanatory drawing at the time of abnormality generation in the 3 coil servo valve control apparatus (conventional method) using the controller which does not include a bumpless switching circuit. FIG. 8 is a time chart (waveform diagram) for explaining changes in currents and the like of respective parts when the failure control system is restored in the three-coil servo valve control device (conventional method) using a controller that does not include the bumpless switching circuit shown in FIG. It is.

Explanation of symbols

  6, 13 ... 3-coil servo valve, 11 ... actuator, 12 ... hydraulic cylinder, 14, 15, 16 ... servo coil, 17 ... torque motor, 18, 19, 20 ... Servo amplifier, 21, 22, 23 ... switch, 24 ... servo valve position detection feedback circuit, 25 ... subtractor, 26a ... control command value (output of control command selector 42), 26a ' ... Control command value (input value of bumpless return means), 26b ... Control command value (output value of bumpless return means), 26 ... Control command value (output of subtractor 25), 27 ..Servo valve position detection feedback value, 28 ... Feedback value of coil current, 31, 32, 33 ... Controller, 34 ... Speed sensor, 35 ... Exhaust temperature sensor, 36 ... Speed setting Fixed value, 37 ... Exhaust temperature set value, 38 ... Speed load control system, 39 ... Exhaust temperature control system, 41 ... Sequence control system, 42 ... Startup control system, 43 ... Control Signal selection unit, 44 ... control command value calculation unit, 55 ... return command, 61 ... adder, 62 ... null bias setting device, 63 ... bumpless return means, 70 ... open Degree sensor

Claims (1)

A plurality of controllers that respectively generate control command values for a plurality of servo coils that drive the servo valves;
A plurality of opening sensors for detecting the opening of the servo valve;
A servo valve position detection feedback circuit for detecting the position of the servo valve based on the output of the opening sensor;
The servo current for driving each servo coil is controlled based on the difference between the control command value output from each of the plurality of controllers and the servo valve position detection feedback value output from the servo valve position detection feedback circuit. A plurality of servo amplifiers,
In a multi-coil servo valve control device having a multiple control system consisting of:
A bumpless return means is provided at each output stage of the plurality of controllers,
The bumpless return means receives the control command value and the servo valve position detection feedback value,
When an abnormality occurs in one of the plurality of opening sensors, the bumpless return means of each of the plurality of controllers detects the servo valve position from the control command value using the control command value as an initial value. Output a control signal that changes at a constant rate up to the feedback value,
Of the plurality of controllers, a controller to which only the opening sensor in which the abnormality has occurred is connected controls the servo valve so that the servo current supplied to the servo coil connected to the controller gradually becomes zero. A multi-coil servo valve control device.

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