JP2010216441A - Rotation control device for gas turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation control device for a gas turbine, suppressing a reduction in rotational speed without increasing a load on a compressor even if a load on the low-pressure gas turbine of a two-shaft gas turbine is interrupted. <P>SOLUTION: This rotation control device for the gas turbine controls the rotating condition of the gas turbine by throttling fuel to a combustor when the load on the two-shaft gas turbine including a compressor, the combustor, a high-pressure gas turbine and the low-pressure gas turbine is interrupted. When the load on the low-pressure gas turbine is interrupted, a signal is transmitted in order to control the opening/closing of a bleed valve bleeding compressed air from the compressor and an inlet guide vane introducing air to the compressor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotation control device for a two-shaft gas turbine having a high-pressure gas turbine and a low-pressure gas turbine.

  The two-shaft gas turbine has a high-pressure gas turbine (HPT) that generates heat energy and a low-pressure gas turbine (LPT) that recovers the generated heat energy, each having two independent rotating shafts. is doing.

  The high-pressure gas turbine is a free turbine having no mechanical connection to the outside, and plays a role of supplying heat energy to the low-pressure gas turbine.

  On the other hand, the low-pressure gas turbine is an energy recovery turbine that does not have the function of generating energy by itself, and when it is linked with the generator, it is incorporated into the power system, so the rotational speed is adjusted according to external demands. There is a need to.

  Furthermore, since the low-pressure gas turbine does not have a device and a system that directly control itself, some method for suppressing acceleration of the low-pressure gas turbine is necessary during an emergency power reduction operation such as when the load is interrupted. .

  As an improvement measure, Patent Document 1 discloses a method of adjusting the amount of air flowing into the compressor by opening and closing an inlet guide vane (IGV).

  Further, a method of reducing the amount of fuel supplied to the combustor is conceivable.

JP 2003-148173 A

  In conventional rotation control when the load of a gas turbine is interrupted, the rotation speed of the gas turbine is reduced by reducing the amount of air flowing into the compressor by reducing the fuel supplied to the combustor or by closing the IGV. The rise of is suppressed.

  Then, it is possible to suppress the increase in the rotational speed to some extent when the load is interrupted, for example, by increasing the closing speed of the fuel control valve for adjusting the fuel supplied to the combustor or the IGV.

  However, the low pressure gas turbine of the two-shaft gas turbine is not equipped with a device or system that directly controls itself, such as a fuel control valve or an IGV.

  Also, in the high-pressure gas turbine of the two-shaft gas turbine, when the IGV is fully opened simultaneously with the load interruption, the amount of air flowing into the compressor increases and the load on the compressor increases. However, there was a possibility that the rotation speed would decrease.

  Therefore, the present invention provides a rotation control device for a gas turbine that can suppress a decrease in the rotation speed without increasing the load on the compressor even when the load of the low-pressure gas turbine of the two-shaft gas turbine is interrupted. Is to provide.

  A rotation control device for a gas turbine according to an embodiment of the present invention supplies a combustor when a load of a compressor, a combustor, a high-pressure gas turbine, and a two-shaft gas turbine having a low-pressure gas turbine is interrupted. The fuel to be squeezed is controlled to control the rotation state of the gas turbine.

  The rotation control device outputs a signal for controlling opening / closing of an extraction valve for extracting compressed air compressed by the compressor and an inlet guide blade for introducing air to the compressor when the load of the low-pressure gas turbine is interrupted. , Respectively, are transmitted to an actuator for driving the extraction valve and the inlet guide vane.

  Further, it is preferable that when the load of the low-pressure gas turbine is cut off, the extraction valve is instantaneously fully closed by the hardware circuit.

  Further, when the load of the low-pressure gas turbine is interrupted, it is preferable to instantaneously close the inlet guide vanes to the intermediate opening in order to suppress the rotation speed of the high-pressure gas turbine.

  Moreover, it is preferable to control the opening and closing of the inlet guide vanes according to the rotation state of the high-pressure gas turbine.

  Further, it is preferable to apply a bias so that the fuel control command value supplied to the combustor becomes the minimum fuel control command value when the load of the low-pressure gas turbine is cut off.

  According to the present invention, there is provided a rotation control device for a gas turbine capable of suppressing a decrease in rotation speed without increasing a load on a compressor even when the load of a low-pressure gas turbine of a two-shaft gas turbine is interrupted. can do.

It is a schematic block diagram of a two-shaft gas turbine. It is an operation | movement figure of the rotation control apparatus at the time of load interruption | blocking. It is a figure which shows the specific example of full open control of an extraction valve. It is a figure which shows the specific example of the opening / closing control of IGV. It is a figure which shows the specific example of the narrowing-down operation | movement of fuel flow instruction | command. It is a figure which shows the time chart in the case of performing bias correction.

  Embodiments of the present invention will be described below.

  The rotation control device for a two-shaft gas turbine described in this embodiment includes a control unit that controls opening / closing of a bleed valve in a passenger compartment when the load of the low-pressure gas turbine is shut off, and when the load is shut off A function of reducing the power of the low-pressure gas turbine by releasing air from the passenger compartment and suppressing an increase in rotational speed is provided.

  In other words, even when the load is cut off during the operation of the two-shaft gas turbine, the increase in the rotational speed is positively suppressed, and the operation can be continued without reaching the stop (trip) operation. is there.

  The two-shaft gas turbine described in the present embodiment includes a compressor that compresses air, a combustor that burns compressed air and fuel to generate high-pressure gas, a high-pressure gas turbine that is driven by high-pressure gas, and a low-pressure gas turbine. It is what has.

  The rotation control device for the two-shaft gas turbine controls the rotation state of the gas turbine by reducing the fuel supplied to the combustor when the load of the low-pressure gas turbine is interrupted. When the load is interrupted, the bleed valve that allows the compressed air from the compressor to flow out is controlled to be fully opened.

  By using such a rotation control device, when the load is shut off, the air flowing into the low-pressure gas turbine is rapidly reduced, and the increase in the rotation speed is suppressed without reducing the load on the compressor. be able to.

  As a result, even in a low-pressure gas turbine that does not have equipment and a system that directly controls itself, it is possible to positively suppress an increase in rotational speed when the load is interrupted.

  Such a rotation control device performs a narrowing operation of fuel supplied to the combustor when the load of the low-pressure gas turbine is interrupted. That is, the amount of decrease in the rotational speed of the high-pressure gas turbine is adjusted by controlling the opening and closing of the inlet guide vanes.

  As a result, when the load is interrupted, the amount of air introduced into the compressor is not rapidly reduced, so that a decrease in the rotational speed of the high-pressure gas turbine can be suppressed.

  Then, after the load is cut off, in order to control the opening and closing of the inlet guide vanes according to the rotation speed of the high pressure gas turbine, an appropriate amount of air is introduced, the load of the compressor is adjusted, and the rotation of the high pressure gas turbine The speed can be kept.

  In addition, a minimum fuel control command for maintaining a flame in the combustor is set in the rotation control device.

  Immediately after the load is cut off, a combustor flame may be lost due to a transient change in the state of the high-pressure gas turbine, but a bias is applied to prevent the combustor flame from being lost. Thus, misfire of the combustor can be prevented.

  This will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration representing the whole of a two-shaft gas turbine including a rotation control device 7 according to an embodiment of the present invention.

  As shown in FIG. 1, the two-shaft gas turbine includes a high-pressure gas turbine 1 (HPT) and a low-pressure gas turbine 2 (LPT), and a compressor 3 and a combustor 4.

  The air compressed by the compressor 3 is combusted together with fuel by the combustor 4, becomes high-temperature combustion gas, and expands by the high-pressure gas turbine 1.

  The high pressure gas turbine 1 drives the compressor 3 and supplies thermal energy to the low pressure gas turbine 2.

  The low pressure gas turbine 2 drives a load 8 such as a generator with the energy supplied from the high pressure gas turbine 1.

  An inlet guide vane (IGV) 6 is provided on the upstream side of the compressor 3. Air is introduced into the compressor 3 by the IGV 6, and the introduced air is compressed by the compressor 3 and the pressure rises. On the other hand, an extraction valve 5 is provided on the downstream side of the compressor 3.

  The IGV 6 and the extraction valve 5 are driven by an actuator (ACT), and a drive command is output from the rotation control device 7 to the actuator.

  Process information such as the rotational speed of the gas turbine, the exhaust gas temperature, the exhaust gas pressure, and the load cutoff information is input to the rotation control device 7.

  The opening degree of the IGV 6 is appropriately controlled according to the operation state of the gas turbine, and the inflow amount of air introduced into the compressor 3 is increased or decreased by increasing or decreasing the opening degree.

  In other words, the actuator that drives the IGV 6 is driven based on the drive command of the rotation control device 7, and is driven to open and close to a predetermined opening according to the operating status of the gas turbine.

  Similarly, a drive command for fuel supply means (fuel control valve or the like) for fuel supplied to the combustor 4 is also output from the rotation control device 7 to the actuator.

  Here, a command from the rotation control device 7 to the actuator that drives the bleed valve 5 is issued by a hardware circuit.

  FIG. 2 shows the operation of the rotation control device 7 when the load is interrupted. Based on FIG. 2, operation | movement of the rotation control apparatus 7 at the time of load interruption is demonstrated.

  In the two-shaft gas turbine as shown in FIG. 1, when the load is interrupted, the bleed valve 5 installed on the downstream side of the compressor 3 is instantaneously fully opened by a drive command from the rotation control device 7 to An increase in the rotational speed of the turbine 2 is suppressed.

  At the same time, by reducing the fuel flow rate of the fuel supplied to the combustor 4 according to the drive command from the rotation control device 7, the base power of the entire system is reduced and the increase in the rotation speed is suppressed.

  Further, in accordance with a drive command from the rotation control device 7, the IGV 6 installed on the upstream side of the compressor 3 is controlled to be opened to an intermediate opening, thereby suppressing a decrease in the rotation speed of the high-pressure gas turbine 1.

  Thereafter, in order to maintain and adjust the balance between the high-pressure gas turbine 1 and the low-pressure gas turbine 2 that are in the no-load rated speed state, the opening degree of the IGV 6 is controlled by controlling the IGV 6 so that the power of the compressor 3 is not changed. By suppressing the degree as small as possible and maintaining the high-pressure gas turbine 1 at a high speed, it becomes possible to continue the independent operation.

  FIG. 3 shows a specific example of full opening control of the bleed valve 5. Based on FIG. 3, the specific example of the full open control of the extraction valve 5 is demonstrated.

  FIG. 3 shows a basic circuit of the extraction valve 5.

  This circuit is composed of a hardware circuit and a software circuit.

  In the normal opening / closing operation, for example, the rotation control device 7 uses a software-processed software circuit that outputs a signal by comparing the rotation speed of the low-pressure gas turbine with the opening / closing speed setting of the extraction valve. It is operated by the command.

  On the other hand, when the load is interrupted, the circuit configuration is such that the hardware circuit is fully opened, and the bleed valve 5 is instantaneously fully opened in one shot.

  FIG. 4 shows a specific example of the opening / closing control of the IGV 6. Based on FIG. 4, the specific example of the opening / closing control of IGV6 is demonstrated.

  FIG. 4A is a basic circuit that controls the opening degree of the IGV 6 set in advance based on the rotation speed information of the high-pressure gas turbine 1 and the inlet temperature information of the compressor 3 input to the rotation control device 7.

  The basic circuit shown in FIG. 4A performs a correction speed calculation using the rotation speed information of the high-pressure gas turbine 1 and the inlet temperature information of the compressor 3 input to the rotation control device 7, and the speed control signal of the IGV 6 A circuit for outputting a signal for instantaneously narrowing down to an intermediate opening as an IGV6 rapid closing command when the load is interrupted, and a circuit for outputting a signal for controlling the maximum opening of the IGV6 The low value of the signal output from these circuits is selected, and the opening setting of the IGV 6, that is, the opening command is output.

  Using such a basic circuit, at the time of load interruption, it is possible to switch to a set value for instantaneously narrowing down to an intermediate opening as a quick closing command of IGV6.

  When the load is shut off, the opening of the IGV 6 is instantaneously controlled to the intermediate opening, and the operation is continued without reducing the rotational speed of the high-pressure gas turbine 1 to the lower limit value of the operation speed. Then, at the stage where the rotation speed starts to decrease, the IGV 6 is gradually moved to the closing side. Thereby, the fall of a rotational speed is suppressed reliably and a speed low trip is not reached.

  After that, in order to maintain the balance between the high-pressure gas turbine 1 and the low-pressure gas turbine 2 that are in the no-load rated speed state, the opening degree of the IGV 6 is controlled as much as possible so as not to change the power of the compressor 3. By keeping it small and maintaining the rotation speed of the high-pressure gas turbine 1 high, it becomes possible to continue the self-sustaining operation.

  In order to realize such an instantaneous operation, function sharing is performed using a master controller and a sub-controller as shown in FIG. 4B, and when the load is interrupted, the operation is instantaneously narrowed down to an intermediate opening.

  FIG. 4B is a diagram showing the function sharing between the master controller and the sub-controller installed in the rotation control device 7.

  That is, the rotation control device 7 is equipped with a master controller that performs normal calculation processing and a sub-controller that performs high-speed calculation processing that can be calculated at a higher speed than the master controller.

  That is, the rotational speed information of the high-pressure gas turbine 1 and the inlet temperature information of the compressor 3 are input to the master controller, and the opening degree of the IGV 6 is set. If it is a normal state, IGV6 is controlled by such opening.

  However, when the load cutoff information is input to the sub-controller, the opening setting command for the IGV6 calculated by the sub-controller is compared with the opening setting command for the IGV6 calculated by the master controller, and the final IGV6 Is output from the sub-controller.

  FIG. 5 shows a specific example of the operation for narrowing the fuel flow rate command. Based on FIG. 5, a specific example of the fuel flow rate command narrowing operation will be described.

  FIG. 5 shows a circuit for calculating a minimum fuel control command for maintaining a flame in the combustor 4.

  The circuit shown in FIG. 5 normally multiplies the inlet side temperature signal of the compressor 3 and the corrected rotational speed signal of the high pressure gas turbine 1 to create a minimum fuel flow rate command. The inlet side temperature signal of the compressor 3 is corrected for the intake air amount of the compressor 3.

  Here, a case where load cutoff information is input to such a circuit will be described.

  When the load cutoff information is input, the opening setting value signal of the IGV 6 and the correction bias signal are added. This is because an addition selection command is input using the input of load shedding information as a trigger.

  This addition signal and the corrected rotation speed signal of the high-pressure gas turbine 1 are further added.

  Here, the corrected rotational speed signal of the high-pressure gas turbine 1 and a further addition signal are selected by a selection circuit. This selection command is also input with the input of load cutoff information as a trigger.

  Finally, the selected signal is multiplied by the inlet-side temperature signal of the compressor 3 to create a minimum fuel flow rate command.

  With such a basic circuit, it is possible to calculate a preset minimum fuel flow rate by correcting the corrected rotational speed of the high-pressure gas turbine 1, the opening setting value of the IGV 6, and the inlet side temperature of the compressor 3.

  It can be seen that it is beneficial to load a bias in order to prevent the loss of flame due to the effects of rapid fuel reduction and NOx reduction operations (water, steam input) at load shedding.

  FIG. 6 shows a time chart for bias correction.

  That is, FIG. 6 shows the relationship between the amount of fuel (FFD: actually indicated by the opening degree% of the valve supplying the fuel) and time, and when the load cutoff signal is inputted, The time elapsed until the minimum fuel (FFDMIN) control command for maintaining the flame is calculated.

  When load cutoff information is input to the fuel flow rate command (FFD) for the combustor 4, first, the degree of opening is rapidly reduced to reduce the fuel supplied to the combustor 4 by a predetermined amount.

  In this case, the amount of compressed air introduced from the compressor 3 to the combustor 4 is also adjusted by adding a correction bias signal to the opening setting value signal of the IGV 6.

  Thereafter, the bias is corrected for a predetermined time (β seconds), and the opening is gradually reduced in order to reduce the fuel amount. In addition, after a predetermined time (β seconds), the opening degree is rapidly reduced in order to reduce the fuel supplied to the combustor 4 by a predetermined amount. Thereafter, the opening degree is not adjusted for a predetermined time and kept constant (bias 2), and then the opening degree is gradually reduced to the minimum fuel (FFDMIN).

  By performing such control, it is possible to calculate a preset minimum fuel flow rate.

  The present invention is applicable to a rotation control device for a two-shaft gas turbine having a high-pressure gas turbine and a low-pressure gas turbine.

DESCRIPTION OF SYMBOLS 1 High pressure gas turbine 2 Low pressure gas turbine 3 Compressor 4 Combustor 5 Extraction valve 6 IGV
7 Rotation control device 8 Load

Claims (5)

A gas turbine that throttles fuel to the combustor and controls the rotation state of the gas turbine when a load of a two-shaft gas turbine having a compressor, a combustor, a high-pressure gas turbine, and a low-pressure gas turbine is interrupted In the rotation control device of
When the load of the low-pressure gas turbine is cut off, a signal for opening / closing control of an extraction valve for extracting compressed air from the compressor and an inlet guide vane for introducing air into the compressor is transmitted. Gas turbine rotation control device. In claim 1,
A rotation control device for a gas turbine, wherein when the load on the low-pressure gas turbine is cut off, the extraction valve is fully closed by a hard circuit. In claim 2,
A rotation control device for a gas turbine, wherein when the load of the low-pressure gas turbine is interrupted, the inlet guide blade is closed to an intermediate opening degree in order to suppress the rotation speed of the high-pressure gas turbine. In claim 2,
A rotation control device for a gas turbine, wherein opening and closing control of the inlet guide vanes is performed according to a rotation state of the high-pressure gas turbine. In claim 4,
A rotation control device for a gas turbine, wherein a bias is applied so that a fuel control command value supplied to the combustor becomes a minimum fuel control command value when a load of the low-pressure gas turbine is cut off. .

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