Apparatus and method for detecting clutch condition in a single-shaft combined cycle power plant

Abstract

To provide a clutch state detection device that can detect a state of a clutch of a uniaxial combined cycle power generation plant in a desired mode.SOLUTION: A clutch state detection device 100 according to one embodiment comprises a speed difference detection unit 101 for detecting whether a rotation speed difference between a rotation speed of a gas turbine 2 and a rotation speed of a steam turbine 4 is equal to or lower than a predetermined value, a steam pressure detection unit 102 for detecting whether an inlet steam pressure of the steam turbine 4 is equal to or higher than a predetermined pressure, and a determination unit 103 for determining that a clutch is in a connection state when it is detected by the speed difference detection unit 101 that the rotation speed difference is equal to or lower than the predetermined value, and it is detected by the steam pressure detection unit 102 that the inlet steam pressure is equal to or higher than the predetermined pressure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a clutch state detection device and method for a single-shaft combined cycle power plant. [Background technology]

[0002] A single-shaft combined cycle power plant has a common rotating shaft that connects a gas turbine, a generator, and a steam turbine. Some such power plants have a clutch provided between the generator and the steam turbine on the rotating shaft, and the clutch switches between a connected state and a disconnected state for power transmission between the generator and the steam turbine.

[0003] In a typical start-up operation of a single-shaft combined cycle power plant equipped with a clutch as described above, first, the power transmission between the generator and the steam turbine is interrupted by the clutch. Next, the gas turbine is rotated, and the generator is rotated by the rotation of the gas turbine. After the gas turbine reaches a rated rotation speed, the generator is connected in parallel to the power grid.

[0004] After the parallel operation, steam generated in the heat recovery boiler by the exhaust gas from the gas turbine is supplied to the steam turbine, which rotates and drives the steam turbine. When the steam turbine reaches a rated rotation speed, the clutch switches the power transmission between the generator and the steam turbine to a connected state, and the rotational power of the steam turbine is also transmitted to the generator. The clutch is usually configured to mechanically and automatically switch to a connected state when the steam turbine reaches the rated rotation speed.

[0005] Figure 4 is a graph illustrating the general start-up procedure mentioned above. In particular, the graph in Figure 4 shows what happens after the gas turbine has reached rated speed and the generator has been paralleled. The horizontal axis of the graph shown is time and the vertical axis is turbine speed. The line marked R1 indicates the gas turbine speed, the line marked R2 indicates the steam turbine speed, and the line marked MW indicates the generator power.

[0006] When the gas turbine rotation speed R1 reaches and is maintained at the rated rotation speed, the generator output MW becomes a basically constant value. Then, at a predetermined timing in this state (at "ST start" on the time axis in Figure 4), the steam turbine is rotated and driven. Thereafter, the steam turbine rotation speed R2 gradually increases and is then maintained at the rated rotation speed. Then, as shown by "clutch connected" on the time axis, the clutch switches the power transmission between the generator and steam turbine to a connected state. As a result, the power of the steam turbine is also transmitted to the generator, and the generator output MW increases.

[0007] In order to perform good control in a single-shaft combined cycle power plant equipped with the above-mentioned clutch, a function for accurately detecting the engagement and disengagement of the clutch is required. Figure 5 shows the schematic configuration of an example of a clutch state detection device that can be used in a single-shaft combined cycle power plant.

[0008] The clutch state detection device in Fig. 5 includes a speed difference detection unit 201 and a holding circuit unit 202. This clutch state detection device focuses on the fact that the rotation speed R1 of the gas turbine and the rotation speed R2 of the steam turbine match in the clutch engaged state, and the speed difference detection unit 201 detects the rotation speed difference (GT / ST rotation speed difference) between the rotation speed R1 of the gas turbine and the rotation speed R2 of the steam turbine. Then, the holding circuit unit 202 receives the detection result of the speed difference detection unit 201, and becomes in a set state when the GT / ST rotation speed difference is small, and becomes in a reset state when the GT / ST rotation speed difference is large. Then, for example, when the holding circuit unit 202 is in a set state, the clutch engaged state is identified, and when it is in a reset state, the clutch disengaged state is identified.

[0009] However, in the configuration shown in Fig. 5, the clutch engagement state may be detected even when the rotation speeds of the gas turbine and the steam turbine are reduced after the clutches are disengaged. Fig. 6 is a graph illustrating an example of how the clutch engagement state is detected by the clutch state detection device shown in Fig. 5 when the rotation speeds of the gas turbine and the steam turbine are reduced.

[0010] In the example of Fig. 6, after the clutch is disengaged, first the steam turbine is stopped, then the gas turbine is stopped, and the rotation speeds R1 and R2 of each gradually decrease. Then, because the turbine time constant of the gas turbine is smaller than the time constant of the steam turbine, the reduced rotation speed R1 of the gas turbine catches up with the reduced rotation speed R2 of the steam turbine, even though the gas turbine was stopped later. In this case, after the gas turbine is stopped but before the steam turbine is stopped, the GT / ST rotation speed difference becomes large, and the clutch disengagement is detected, but after the steam turbine is stopped, the GT / ST rotation speed difference becomes small, and the clutch engagement state is detected.

[0011] In normal startup operation, when the power transmission between the generator and the steam turbine is connected, the steam supply is increased to increase the output of the steam turbine. For example, if the process of increasing the steam supply is automated so as to start in response to detection of the clutch connection state, a situation may arise in which the output of the steam turbine is increased in response to the clutch connection state detected during the speed reduction as described above. In this case, an undesirable operation may occur. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2003-13709 A Summary of the Invention [Problem to be solved by the invention]

[0013] Therefore, an object of the present invention is to provide a clutch state detection device and method capable of detecting the state of the clutch of a single-shaft combined cycle power plant in a desired manner. [Means for solving the problem]

[0014] In one embodiment, a clutch state detection device for a single-shaft combined cycle power plant is a clutch state detection device for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a common rotating shaft, and power transmission between the generator and the steam turbine is switched between an engaged state and a disconnected state by a clutch. This clutch state detection device includes: a speed difference detection unit that detects whether a rotational speed difference between a rotational speed of the gas turbine and a rotational speed of the steam turbine is equal to or less than a predetermined value, a steam pressure detection unit that detects whether an inlet steam pressure of the steam turbine is equal to or more than a predetermined pressure, and a determination unit that determines that the clutch is in an engaged state when the speed difference detection unit detects that the rotational speed difference is equal to or less than the predetermined value and the steam pressure detection unit detects that the inlet steam pressure is equal to or more than the predetermined pressure.

[0015] In one embodiment, a clutch state detection device for a single-shaft combined cycle power plant is a clutch state detection device for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a shared rotating shaft, and power transmission between the generator and the steam turbine is switched between an engaged state and a disconnected state by a clutch. This clutch state detection device includes a speed difference detection unit that detects whether a rotational speed difference between a rotational speed of the gas turbine and a rotational speed of the steam turbine is equal to or less than a predetermined value, a power generation output detection unit that detects whether a power generation output of the generator has increased, and a determination unit that determines that the clutch is in an engaged state when the speed difference detection unit detects that the rotational speed difference is equal to or less than a predetermined value and the power generation output detection unit detects that the power generation output has increased.

[0016] In one embodiment, a clutch state detection method for a single-shaft combined cycle power plant is a clutch state detection method for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a shared rotating shaft, and power transmission between the generator and the steam turbine is switched between an engaged state and a disconnected state by a clutch. This method includes a speed difference detection step of detecting whether a rotational speed difference between a rotational speed of the gas turbine and a rotational speed of the steam turbine is equal to or less than a predetermined value, a steam pressure detection step of detecting whether an inlet steam pressure of the steam turbine is equal to or more than a predetermined pressure, and a determination step of determining that the clutch is in an engaged state when the speed difference detection step detects that the rotational speed difference is equal to or less than the predetermined value and the steam pressure detection step detects that the inlet steam pressure is equal to or more than the predetermined pressure.

[0017] In one embodiment, a clutch state detection method for a single-shaft combined cycle power plant is a clutch state detection method for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a shared rotating shaft, and power transmission between the generator and the steam turbine is switched between an engaged state and a disconnected state by a clutch. This method includes a speed difference detection step of detecting whether a rotational speed difference between a rotational speed of the gas turbine and a rotational speed of the steam turbine is equal to or smaller than a predetermined value, a power generation output detection step of detecting whether a power generation output of the generator has increased, and a determination step of determining that the clutch is in an engaged state when the speed difference detection step detects that the rotational speed difference is equal to or smaller than a predetermined value and the power generation output detection step detects that the power generation output has increased. Effect of the Invention

[0018] According to the present invention, the state of the clutch of a single-shaft combined cycle power plant can be detected in a desired manner. [Brief description of the drawings]

[0019] [Figure 1]1 is a diagram illustrating a schematic configuration of a single-shaft combined cycle power plant equipped with a clutch state detection device according to a first embodiment. [Diagram 2] 1 is a diagram illustrating a schematic configuration of a clutch state detection device according to a first embodiment. [Diagram 3] FIG. 4 is a diagram illustrating a schematic configuration of a clutch state detection device according to a second embodiment. [Figure 4] FIG. 1 is a graph illustrating a typical start-up operation of a single-shaft combined cycle power plant. [Diagram 5] FIG. 1 is a diagram showing a schematic configuration of an example of a clutch state detection device that can be used in a single-shaft combined cycle power plant. [Figure 6] 6 is a graph illustrating an example of how the clutch state detection device shown in FIG. 5 detects a clutch engagement state during deceleration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Each embodiment will be described in detail below with reference to the accompanying drawings.

[0021] <First embodiment> FIG. 1 shows a schematic diagram of a single-shaft combined cycle power plant 1 equipped with a clutch state detection device 100 according to a first embodiment.

[0022] The single-shaft combined cycle power plant 1 in Fig. 1 includes a gas turbine 2, a generator 3, and a steam turbine 4. The gas turbine 2, the generator 3, and the steam turbine 4 share a single rotating shaft 5 and are connected by this rotating shaft 5. In this way, a power train of the single-shaft combined cycle power plant 1 is formed.

[0023] The gas turbine 2, the generator 3, and the steam turbine 4 are arranged on a rotating shaft 5 such that the generator 3 is located between the gas turbine 2 and the steam turbine 4. A clutch 6 is provided in a portion of the rotating shaft 5 between the generator 3 and the steam turbine 4, and the clutch 6 is configured to switch the power transmission between the generator 3 and the steam turbine 4 between a connected state and a disconnected state.

[0024] When the rotational speed of the gas turbine 2 and generator 3 matches the rotational speed of the steam turbine 4, the part of the clutch 6 on the generator 3 side engages with the part on the steam turbine 4 side, and when the speed difference between the rotational speed of the gas turbine 2 and generator 3 and the rotational speed of the steam turbine 4 becomes large enough to exceed a certain level, the part on the generator 3 side and the part on the steam turbine 4 side separate, and the clutch 6 enters a disconnected state.

[0025] When the clutch 6 is in an engaged state, the rotation of the steam turbine 4 is transmitted to the generator 3 via the clutch 6, and power transmission between the generator 3 and the steam turbine 4 is in a connected state. On the other hand, when the clutch 6 is in a disengaged state, the rotation of the steam turbine 4 is not transmitted to the generator 3 via the clutch 6, and power transmission between the generator 3 and the steam turbine 4 is in a disconnected state.

[0026] When the power transmission between the generator 3 and the steam turbine 4 is in a connected state, it becomes possible to simultaneously transmit the rotational power of the gas turbine 2 and the rotational power of the steam turbine 4 to the generator 3, thereby increasing the power generation output. The structure of the clutch 6 is not particularly limited, and for example, a meshing clutch such as a helical spline engagement, a friction clutch, or the like can be used.

[0027] Fuel f is supplied to the gas turbine 2 via a fuel control valve 7, and steam Sh, Sr from a heat recovery steam generator (not shown) or the like is supplied to the steam turbine 4 via steam control valves 8, 9.

[0028] The steam turbine 4 in this embodiment has, as an example, a high-pressure turbine 10, an intermediate-pressure turbine 11, and a low-pressure turbine 12, and the high-pressure turbine 10 is rotated by high-pressure steam Sh supplied from a heat recovery boiler via a high-pressure steam control valve 8. The heat recovery boiler generates high-pressure steam by heat of the exhaust gas from the gas turbine 2 and supplies it to the high-pressure turbine 10 side.

[0029] The intermediate pressure turbine 11 is supplied with reheated steam Sr via the reheat steam control valve 9 and is rotated by the reheated steam Sr. The reheated steam Sr is generated, for example, by heating the steam discharged from the high pressure turbine 10 by a reheater (not shown). The pressure of such reheated steam Sr is lower than the pressure of the high pressure steam.

[0030] On the other hand, the low-pressure turbine 12 is configured to be rotated by the steam discharged from the intermediate-pressure turbine 11. Note that the steam turbine 4 is not limited to the example shown in the figure, and may be, for example, one composed of a high-pressure turbine and a low-pressure turbine, or one composed of a single turbine.

[0031] A first steam pressure sensor 13 is provided in the steam flow path between a steam inlet formed in the casing of the intermediate-pressure turbine 11 and the reheat steam control valve 9, and a second steam pressure sensor 14 is provided in the steam flow path between a steam inlet formed in the casing of the high-pressure turbine 10 and the high-pressure steam control valve 8. The first steam pressure sensor 13 detects the inlet steam pressure of the intermediate-pressure turbine 11 flowing into the steam inlet of the intermediate-pressure turbine 11, and the second steam pressure sensor 14 detects the inlet steam pressure of the high-pressure turbine 10 flowing into the steam inlet of the high-pressure turbine 10.

[0032] Furthermore, in this embodiment, a first speed sensor 15 for detecting the rotation speed of the gas turbine 2 and a second speed sensor 16 for detecting the rotation speed of the steam turbine 4 are further provided. The first speed sensor 15 is disposed on the generator 3 and gas turbine 2 side with respect to the clutch 6, and the second speed sensor 16 is disposed on the steam turbine 4 side with respect to the clutch 6. Each of these sensors 15, 16 may be, for example, a rotary encoder or the like.

[0033] The start-up operation of the above-mentioned single-shaft combined cycle power plant 1 is performed in the same procedure as the general start-up operation described above. That is, at the time of start-up, first, the power transmission between the generator 3 and the steam turbine 4 is interrupted by the clutch 6. Next, the gas turbine 2 is rotated, and the generator 3 is rotated by the rotation of the gas turbine 2. Then, after the gas turbine 2 reaches a rated rotation speed, the generator 3 is connected in parallel to the power grid. Then, after the above-mentioned parallel connection, high-pressure steam Sh generated in the heat recovery boiler by the exhaust gas of the gas turbine 2 is supplied to the steam turbine 4, and the steam turbine 4 is rotated.

[0034] Here, the high-pressure steam control valve 8 gradually increases the valve opening so that the rotation speed of the steam turbine 4 increases toward the rated rotation speed, thereby increasing the supply amount of high-pressure steam Sh. When the supply amount of high-pressure steam Sh is increased in this manner, the inlet steam pressure of the high-pressure turbine 10 increases in proportion to the supply amount. The reheat steam control valve 9 also gradually increases the valve opening so that the rotation speed of the steam turbine 4 increases toward the rated rotation speed, thereby increasing the supply amount of reheat steam Sr. When the supply amount of reheat steam Sr is increased in this manner, the inlet steam pressure of the intermediate pressure turbine 11 also increases in proportion to the supply amount. Then, when the steam turbine 4 reaches the rated rotation speed, the clutch 6 switches the power transmission between the generator 3 and the steam turbine 4 to a connected state, and the power of the steam turbine 4 is also transmitted to the generator 3.

[0035] The clutch state detection device 100 according to this embodiment will be described below.

[0036] Fig. 2 shows a schematic configuration of the clutch state detection device 100. As shown in Fig. 2, the clutch state detection device 100 according to the present embodiment has a speed difference detection unit 101, a steam pressure detection unit 102, and a determination unit 103.

[0037] The clutch state detection device 100 is composed of, for example, a PLC (Programmable Logic Controller) including a processor, and may realize various functions (the functions of the speed difference detection unit 101, the steam pressure detection unit 102, and the determination unit 103) by reading and executing necessary programs from a storage unit. The storage unit is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, a hard disk, an optical disk, or the like.

[0038] The term "processor" refers to a circuit such as a central processing unit (CPU), an application specific integrated circuit (ASIC), a programmable logic device (SPLD, CPLD), a field programmable gate array (FPGA), etc. Meanwhile, the clutch state detection device 100 may also be configured as an IC chip having a logic circuit.

[0039] A speed difference detection unit 101 detects whether the rotational speed difference between the rotational speed of the gas turbine 2 and the rotational speed of the steam turbine 4 is equal to or less than a predetermined value, and a steam pressure detection unit 102 detects whether the inlet steam pressure of the steam turbine 4 is equal to or greater than a predetermined pressure. Then, a determination unit 103 determines that the clutch 6 is in an engaged state when the speed difference detection unit 101 detects that the rotational speed difference is equal to or less than the predetermined value and the steam pressure detection unit 102 detects that the inlet steam pressure is equal to or greater than the predetermined pressure.

[0040] In detail, the speed difference detection unit 101 acquires information on the rotational speed R1 of the gas turbine 2 detected by the first speed sensor 15 and information on the rotational speed R2 of the steam turbine 4 detected by the second speed sensor 16, and compares the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4 with a first predetermined value (predetermined value) and a second predetermined value (another predetermined value) that is greater than the first predetermined value.

[0041] When the speed difference detection unit 101 detects that the rotation speed difference is equal to or smaller than a first predetermined value, it inputs a “GT / ST rotation speed difference small” signal indicating that the rotation speed difference is small to the judgment unit 103, and when it detects that the rotation speed difference is equal to or larger than a second predetermined value, it inputs a “GT / ST rotation speed difference large” signal indicating that the rotation speed difference is large to the judgment unit 103.

[0042] The speed difference detection unit 101 is not limited to the above embodiment, and may be configured to compare the rotation speed difference with one predetermined value, and if the rotation speed difference is equal to or greater than the predetermined value, input a signal of "GT / ST rotation speed difference small" to the determination unit 103, and if the rotation speed difference is less than the predetermined value, input a signal of "GT / ST rotation speed difference large" to the determination unit 103.

[0043] In addition, the steam pressure detection unit 102 is configured to acquire information on the inlet steam pressure P1 of the intermediate pressure turbine 11 detected by the first steam pressure sensor 13 and information on the inlet steam pressure P2 of the high pressure turbine 10 detected by the second steam pressure sensor 14, compare the inlet steam pressure P1 of the intermediate pressure turbine 11 with a first predetermined pressure, and compare the inlet steam pressure P2 of the high pressure turbine 10 with a second predetermined pressure.

[0044] In detail, when the steam pressure detection unit 102 detects that the inlet steam pressure P1 of the intermediate pressure turbine 11 is equal to or higher than the first predetermined pressure as a predetermined pressure and the inlet steam pressure P2 of the high pressure turbine 10 is equal to or higher than the second predetermined pressure as a predetermined pressure, the steam pressure detection unit 102 determines that "the inlet steam pressure of the steam turbine 4 is equal to or higher than the predetermined pressure." When the steam pressure detection unit 102 determines that the inlet steam pressure of the steam turbine 4 is equal to or higher than the predetermined pressure in this manner, it inputs a "ST output present" signal to the determination unit 103. Note that this "ST output present" signal is generated as a signal indicating that the inlet steam pressure of the steam turbine 4 is rising due to an increase in the steam supply amount.

[0045] On the other hand, when it is not determined that the inlet steam pressure of the steam turbine 4 is equal to or higher than the predetermined pressure as described above, the steam pressure detection unit 102 inputs a "no ST output" signal to the determination unit 103. In this embodiment, a case where it is not determined that the inlet steam pressure of the steam turbine 4 is equal to or higher than the predetermined pressure means a case where the inlet steam pressure P1 of the intermediate-pressure turbine 11 is lower than the first predetermined pressure and / or the inlet steam pressure P2 of the high-pressure turbine 10 is lower than the second predetermined pressure.

[0046] The steam pressure detection unit 102 may be configured to input a "ST output present" signal to the determination unit 103 when it detects that either the inlet steam pressure P1 of the intermediate pressure turbine 11 is equal to or higher than the first predetermined pressure or the inlet steam pressure P2 of the high pressure turbine 10 is equal to or higher than the second predetermined pressure. In this case, the steam pressure detection unit 102 may be configured to acquire only information on the inlet steam pressure P1 of the intermediate pressure turbine 11. The steam pressure detection unit 102 may also be configured not to generate a "ST output absent" signal.

[0047] The determination unit 103 in this embodiment includes a logical AND gate unit 104, a logical OR gate unit 105, and a holding circuit unit .

[0048] The logical AND gate unit 104 is configured to input an input signal In1 to the holding circuit unit 106 when an AND condition is met in which both a signal indicating "small GT / ST rotation speed difference" from the speed difference detection unit 101 and a signal indicating "ST output present" from the steam pressure detection unit 102 are acquired, and to not input the input signal In1 to the holding circuit unit 106 when the AND condition is not satisfied.

[0049] The logical OR gate unit 105 is configured to input an input signal In2 to the holding circuit unit 106 when an OR condition is met in which at least one of a signal indicating a “large GT / ST rotation speed difference” from the speed difference detection unit 101 and a signal indicating a “no ST output” from the steam pressure detection unit 102 is acquired, and to not input the input signal In2 to the holding circuit unit 106 when no signal is acquired.

[0050] The holding circuit unit 106 is configured to be in a set state when it receives an input signal In1 from the AND gate unit 104, and to be in a reset state when it receives an input signal In2 from the OR gate unit 105. When the holding circuit unit 106 is in the set state, it generates a signal indicating that the clutch 6 is in an engaged state ("clutch engaged" in FIG. 2), and when the holding circuit unit 106 is in the reset state, it generates a signal indicating that the clutch 6 is in a disengaged state ("clutch disengaged" in FIG. 2). By referring to these signals, it is possible to determine the current state of the clutch 6.

[0051] Although the holding circuit unit 106 in this embodiment uses a flip-flop circuit configuration, the configuration is not particularly limited.

[0052] Hereinafter, the operation of the clutch state detection device 100 will be described with reference to the start-up operation shown in FIG. 4 and the state during deceleration after the clutch is disengaged shown in FIG.

[0053] 4, after the gas turbine 2 reaches the rated rotation speed, high-pressure steam Sh and the like generated in the heat recovery boiler by the exhaust gas of the gas turbine 2 are supplied to the steam turbine 4, which rotates and drives the steam turbine 4. Then, the rotation speed of the steam turbine 4 gradually increases, and when the rotation speed of the steam turbine 4 reaches the rated rotation speed, the clutch 6 connects the power transmission between the generator 3 and the steam turbine 4.

[0054] Here, as described above, the rotational speed of the steam turbine 4 gradually increases, thereby reducing the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4. At this time, when the speed difference detection unit 101 detects that the rotational speed difference is equal to or less than the first predetermined value, the clutch state detection device 100 inputs a "GT / ST rotational speed difference small" signal, indicating that the rotational speed difference is small, from the speed difference detection unit 101 to the determination unit 103 (speed difference detection process).

[0055] Furthermore, when the rotation speed of the steam turbine 4 gradually increases toward the rated rotation speed as described above, the inlet steam pressure P1 of the intermediate pressure turbine 11 and the inlet steam pressure P2 of the high pressure turbine 10 gradually increase. Then, when the steam pressure detection unit 102 detects that the inlet steam pressure P1 of the intermediate pressure turbine 11 is equal to or higher than the first predetermined steam pressure and the inlet steam pressure P2 of the high pressure turbine 10 is equal to or higher than the second predetermined pressure, the clutch state detection device 100 determines that the inlet steam pressure of the steam turbine 4 is equal to or higher than the predetermined pressure, and inputs a "ST output present" signal from the steam pressure detection unit 102 to the determination unit 103 (steam pressure detection process).

[0056] As described above, when the "GT / ST rotation speed difference small" signal and the "ST output present" signal are input to the judgment unit 103 (more specifically, the AND gate unit 104), a logical AND is established in the AND gate unit 104, and the clutch state detection device 100 inputs the input signal In1 from the AND gate unit 104 to the holding circuit unit 106. At this time, the holding circuit unit 106 is set, and generates a signal indicating that the clutch 6 is in an engaged state. As a result, the clutch state detection device 100 judges that the current state of the clutch 6 is in an engaged state, and more specifically, judges that the clutch 6 is in an engaged state at the time of startup (judgment step).

[0057] On the other hand, during speed reduction after clutch disengagement as shown in Fig. 6, after the clutch is disengaged, first the steam turbine 4 is stopped, then the gas turbine 2 is stopped, and the rotation speed R1 of the gas turbine 2 and the rotation speed R2 of the steam turbine 4 gradually decrease. Then, even though the gas turbine 2 is stopped later, the rotation speed R1 of the gas turbine 2 catches up with the decreased rotation speed R2 of the steam turbine 4.

[0058] At this time, in the clutch state detection device 100, after the gas turbine 2 is stopped and before the steam turbine 4 is stopped, the speed difference detection unit 101 detects that the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4 is equal to or greater than the second predetermined value. Then, a signal indicating that the rotational speed difference is large is input from the speed difference detection unit 101 to the determination unit 103. As a result, in the clutch state detection device 100, a logical sum is established in the logical sum gate unit 105 in the determination unit 103, and the input signal In2 is input from the logical sum gate unit 105 to the holding circuit unit 106. At this time, the holding circuit unit 106 is reset, a signal indicating that the clutch 6 is in a disengaged state is generated, and the clutch state detection device 100 determines that the current state of the clutch 6 is in a disengaged state.

[0059] Furthermore, when the rotation speed R2 of the steam turbine 4 decreases, the inlet steam pressure P1 of the intermediate pressure turbine 11 and the inlet steam pressure P2 of the high pressure turbine 10 gradually decrease. Therefore, the clutch state detection device 100 detects, at a certain timing, by the steam pressure detection unit 102, that the inlet steam pressure P1 of the intermediate pressure turbine 11 is less than a first predetermined pressure and / or the inlet steam pressure P2 of the high pressure turbine 10 is less than a second predetermined pressure. At this time, a signal of "no ST output" is input from the steam pressure detection unit 102 to the determination unit 103. This also resets the holding circuit unit 106, generates a signal indicating that the clutch 6 is in a disengaged state, and the clutch state detection device 100 determines that the current state of the clutch 6 is in a disengaged state.

[0060] Furthermore, when the rotational speed R1 of the gas turbine 2 catches up with the reduced rotational speed R2 of the steam turbine 4, the speed difference detection unit 101 detects that the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4 is equal to or less than the first predetermined value, and a signal indicating that the rotational speed difference is small is input from the speed difference detection unit 101 to the judgment unit 103.

[0061] However, when the rotation speed R2 of the steam turbine 4 decreases, the inlet steam pressure P1 of the intermediate pressure turbine 11 and the inlet steam pressure P2 of the high pressure turbine 10 decrease. Therefore, the clutch state detection device 100 does not detect that the inlet steam pressure P1 of the intermediate pressure turbine 11 is equal to or higher than the first predetermined pressure and the inlet steam pressure P2 of the high pressure turbine 10 is equal to or higher than the second predetermined pressure. Therefore, the signal "ST output present" is not input to the AND gate unit 104 of the determination unit 103. Therefore, the AND is not established in the AND gate unit 104, and the input signal In1 is not input from the AND gate unit 104 to the holding circuit unit 106. Therefore, the reset state of the holding circuit unit 106 is maintained, and it is not detected that the clutch 6 is in the engaged state.

[0062] The clutch state detection device 100 according to the present embodiment described above includes a speed difference detection unit 101 which detects whether the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed of the steam turbine 4 is equal to or less than a predetermined value (in this example, a first predetermined value), a steam pressure detection unit 102 which detects whether the inlet steam pressure of the steam turbine 4 is equal to or greater than a predetermined pressure (in this example, inlet steam pressure P1 of the intermediate pressure turbine ≧ first predetermined pressure, and inlet steam pressure P2 of the high pressure turbine ≧ second predetermined pressure), and a judgment unit 103 which judges that the clutch 6 is in an engaged state when the speed difference detection unit 101 detects that the rotational speed difference is equal to or less than the predetermined value and the steam pressure detection unit 102 detects that the inlet steam pressure is equal to or greater than the predetermined pressure.

[0063] In other words, this clutch state detection device 100 determines whether the clutch 6 is in an engaged state by taking into consideration not only whether the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4 has become small, but also whether the inlet steam pressure has increased.

[0064] This allows the state of the clutch 6 to be detected in a desired manner. Specifically, the engagement state of the clutch 6 can be detected in a manner that detects only the engagement state of the clutch 6 at start-up and excludes detection of the engagement state of the clutch 6 during deceleration. In particular, in this embodiment, the clutch 6 determines the clutch engagement state based on an increase in the inlet steam pressure as one of the criteria, which is advantageous in terms of the responsiveness of the determination.

[0065] In addition, the speed difference detection unit 101 in this embodiment also detects whether the rotational speed difference is equal to or greater than another predetermined value (second predetermined value) that is greater than the predetermined value (first predetermined value), and determines that the rotational speed difference is large when the rotational speed difference is equal to or greater than the other predetermined value. Then, the determination unit 103 determines that the clutch 6 is in a disengaged state when the speed difference detection unit 101 detects that the rotational speed difference is equal to or greater than the other predetermined value.

[0066] In this way, when the speed difference detection unit 101 judges whether the rotation speed difference is small or large using two judgment criteria (a predetermined value and another predetermined value), it is possible to prevent the rotation speed difference from being undesirably detected as small or large due to a detection error of the rotation speed, thereby improving the reliability of the clutch state judgment performed by the judgment unit 103.

[0067] In addition, in this embodiment, the judgment unit 103 judges that the clutch 6 is in a disengaged state when the speed difference detection unit 101 does not detect that the rotational speed difference is below a predetermined value (more specifically, when the rotational speed difference is not detected to be below a first predetermined value and is detected to be above a second predetermined value) and / or when the steam pressure detection unit 102 does not detect that the inlet steam pressure is above a predetermined pressure (more specifically, when the inlet steam pressure P1 of the intermediate pressure turbine ≧ the first predetermined pressure and the inlet steam pressure P2 of the high pressure turbine ≧ the second predetermined pressure).

[0068] In this manner, in a configuration in which the judgment unit 103 judges that the clutch 6 is in a disengaged state when at least one of the two conditions is satisfied, the responsiveness in judging the disengaged state of the clutch 6 can be improved.

[0069] Furthermore, when it is detected that the inlet steam pressure P1 of the intermediate pressure turbine is equal to or greater than the first predetermined pressure and the inlet steam pressure P2 of the high pressure turbine is equal to or greater than the second predetermined pressure, the steam pressure detection unit 102 in this embodiment inputs an "ST output present" signal indicating that the inlet steam pressure of the steam turbine 4 is rising to the determination unit 103. The "ST output present" signal is an index for determining the clutch engagement state, and in this embodiment, the determination criterion for generating this signal is when two conditions are satisfied simultaneously. This improves the reliability when determining the clutch engagement state.

[0070] <Second embodiment> Next, a second embodiment will be described with reference to Fig. 1 and Fig. 3. Fig. 3 shows a schematic configuration of a clutch state detection device 110 according to the second embodiment. The clutch state detection device 110 shown in Fig. 3 has a speed difference detection unit 111, a power generation output detection unit 112, and a determination unit 113. The clutch state detection device 110 is applied to the single-shaft combined cycle power plant 1 shown in Fig. 1, and the components described in Fig. 1 may be used in the following description of the clutch state detection device 110, but detailed description thereof will be omitted.

[0071] In this embodiment, the speed difference detection unit 111 detects whether the rotational speed difference between the rotational speed of the gas turbine 2 and the rotational speed of the steam turbine 4 is equal to or less than a predetermined value, and the power generation output detection unit 112 detects whether the power generation output of the generator 3 has increased. Then, the determination unit 113 determines that the clutch 6 is in an engaged state when the speed difference detection unit 101 detects that the rotational speed difference is equal to or less than a predetermined value and the power generation output detection unit 112 detects that the power generation output has increased.

[0072] In detail, the speed difference detection unit 111 acquires information on the rotational speed R1 of the gas turbine 2 detected by the first speed sensor 15 and information on the rotational speed R2 of the steam turbine 4 detected by the second speed sensor 16, and compares the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4 with a first predetermined value (predetermined value) and a second predetermined value (another predetermined value) that is greater than the first predetermined value.

[0073] When the speed difference detection unit 111 detects that the rotation speed difference is equal to or smaller than a first predetermined value, it inputs a “GT / ST rotation speed difference small” signal indicating that the rotation speed difference is small to the judgment unit 103, and when the rotation speed difference is equal to or larger than a second predetermined value, it inputs a “GT / ST rotation speed difference large” signal indicating that the rotation speed difference is large to the judgment unit 113.

[0074] The power generation output detection unit 112 sequentially calculates the difference between the power generation outputs of the generator 3 at two different times, and determines that the power generation output has increased when the calculated difference is equal to or greater than a predetermined output value. When the power generation output detection unit 112 determines that the power generation output has increased, it inputs a "generator output increase" signal indicating that the power generation output has increased to the determination unit 103. In this embodiment, it is assumed that the "generator output increase" signal is generated when the power generation output increases to a level at which the clutch 6 transitions from a disengaged state to an engaged state. In this embodiment, the power generation output detection unit 112 is configured to sequentially acquire information on the power generation output MW of the generator 3 in order to sequentially calculate the difference between the power generation outputs of the generator 3 at two different times.

[0075] The processing by the power generation output detection unit 112 is not limited to the above-mentioned manner, and for example, the increase rate of the power generation output in a specified period, an integral value, etc. may be compared with a corresponding threshold value to determine whether the power generation output of the generator 3 has increased.

[0076] Moreover, the judgment unit 113 in this embodiment is composed of a logical AND gate unit 114 and a holding circuit unit 116. The logical AND gate unit 114 is configured to input the input signal In1 to the holding circuit unit 116 when an AND condition is met in which both a signal indicating "small GT / ST rotation speed difference" from the speed difference detection unit 111 and a signal indicating "increased generator output" from the power generation output detection unit 112 are acquired, and not to input the input signal In1 to the holding circuit unit 116 when the AND condition is not satisfied.

[0077] As described above, the holding circuit unit 116 is configured to receive the input signal In1 from the AND gate unit 114 or the signal "GT / ST rotation speed difference large" from the speed difference detection unit 111. The holding circuit unit 116 is configured to enter a set state when it acquires the input signal In1 from the AND gate unit 114, and to enter a reset state when it acquires the signal "GT / ST rotation speed difference large" from the speed difference detection unit 111.

[0078] When in the set state, the holding circuit unit 116 generates a signal indicating that the clutch 6 is engaged ("clutch engaged" in FIG. 3), and when in the reset state, the holding circuit unit 116 generates a signal indicating that the clutch 6 is disengaged ("clutch disengaged" in FIG. 3). By referring to these signals, it is possible to determine the current state of the clutch 6.

[0079] Hereinafter, the operation of the clutch state detection device 110 will be described with reference to the start-up operation shown in FIG. 4 and the state during deceleration after the clutch is disengaged shown in FIG.

[0080] 4, the rotational speed R2 of the steam turbine 4 gradually increases, thereby reducing the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4. At this time, when the speed difference detection unit 111 of the clutch state detection device 110 detects that the rotational speed difference is equal to or less than the first predetermined value, the clutch state detection device 110 inputs a "GT / ST rotational speed difference small" signal indicating that the rotational speed difference is small from the speed difference detection unit 111 to the determination unit 113.

[0081] Furthermore, when the rotation speed of the steam turbine 4 reaches the rated rotation speed, the clutch 6 is engaged and the rotational power of the steam turbine 4 is transmitted to the generator 3, thereby increasing the power generation output. As a result, the power generation output detection unit 112 detects that the difference between the power generation outputs of the generator at two different points in time is equal to or greater than a predetermined output value, and inputs a "generator output increase" signal indicating that the power generation output has increased to the determination unit 103.

[0082] As described above, when the "GT / ST rotation speed difference small" signal and the "generator output increase" signal are input to the judgment unit 103 (more specifically, the AND gate unit 114), a logical AND is established in the AND gate unit 114, and the clutch state detection device 110 inputs the input signal In1 from the AND gate unit 114 to the holding circuit unit 116. At this time, the holding circuit unit 116 is set and generates a signal indicating that the clutch 6 is in an engaged state. As a result, the clutch state detection device 110 determines that the current state of the clutch 6 is in an engaged state, and more specifically, determines that the clutch 6 is in an engaged state at the time of startup.

[0083] On the other hand, during speed reduction after clutch disengagement as shown in Fig. 6, after the clutch is disengaged, first the steam turbine 4 is stopped, then the gas turbine 2 is stopped, and the rotation speed R1 of the gas turbine 2 and the rotation speed R2 of the steam turbine 4 gradually decrease. Then, even though the gas turbine 2 is stopped later, the rotation speed R1 of the gas turbine 2 catches up with the decreased rotation speed R2 of the steam turbine 4.

[0084] At this time, in the clutch state detection device 110, after the steam turbine 4 is stopped and before the gas turbine 2 is stopped, the speed difference detection unit 111 detects that the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4 is equal to or greater than the second predetermined value. Then, a "GT / ST rotational speed difference large" signal indicating that the rotational speed difference is large is input from the speed difference detection unit 111 to the determination unit 113. As a result, in the clutch state detection device 110, the holding circuit unit 116 in the determination unit 113 is reset, a signal indicating that the clutch 6 is in a disengaged state is generated, and the clutch state detection device 110 determines that the current state of the clutch 6 is in a disengaged state.

[0085] On the other hand, thereafter, when the rotational speed R1 of the gas turbine 2 catches up with the reduced rotational speed R2 of the steam turbine 4, the speed difference detection unit 111 detects that the rotational speed difference between the rotational speed R1 of the gas turbine 2 and the rotational speed R2 of the steam turbine 4 is less than the first predetermined value, and a signal "GT / ST rotational speed difference small" indicating that the rotational speed difference is small is input from the speed difference detection unit 111 to the judgment unit 113 (more specifically, the logical AND gate unit 114).

[0086] However, when the rotation speed R1 of the gas turbine 2 decreases, the gas turbine 2 is disconnected, and the power generation output is 0. Therefore, in the clutch state detection device 110, the power generation output detection unit 112 does not input a signal of "generator output increase" to the determination unit 103 (more specifically, the logical product gate unit 114). Therefore, the logical product is not established in the logical product gate unit 114, and the input signal In1 is not input from the logical product gate unit 114 to the holding circuit unit 106. Therefore, the reset state of the holding circuit unit 106 is maintained, and it is not detected that the clutch 6 is in the connected state. In this embodiment, when the speed is reduced after the clutch is disengaged, the steam turbine 4 is stopped, and then the generator 3 is disconnected from the power grid, and then the gas turbine 2 is stopped.

[0087] The clutch state detection device 110 according to the second embodiment described above determines whether the clutch 6 is in an engaged state, taking into consideration not only whether the rotation speed difference between the rotation speed R1 of the gas turbine 2 and the rotation speed R2 of the steam turbine 4 has become small, but also whether the power generation output has increased at the level at which the clutch 6 has transitioned from a disengaged state to an engaged state. This allows the state of the clutch 6 to be detected in a desired manner, as in the first embodiment. That is, specifically, the engagement state of the clutch 6 can be detected in a manner that detects only the engagement state of the clutch 6 at start-up and excludes detection of the engagement state of the clutch 6 during deceleration. In particular, in this embodiment, whether the power generation output has increased at the level at which the clutch 6 has transitioned from a disengaged state to an engaged state is determined from the actual power generation output MW, which is advantageous in terms of the reliability of the determination.

[0088] Although the embodiment has been described above, the above embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. Such embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0089] Reference Signs List 1...single-shaft combined cycle power plant, 2...gas turbine, 3...generator, 4...steam turbine, 5...rotating shaft, 6...clutch, 7...fuel control valve, 8...high-pressure steam control valve, 9...reheat steam control valve, 10...high-pressure turbine, 11...intermediate-pressure turbine, 12...low-pressure turbine, 13...first steam pressure sensor, 14...second steam pressure sensor, 15...first speed sensor, 16...second speed sensor, 100,110...clutch state detection device, 101,111...speed difference detection section, 102...steam pressure detection section, 103,113...judgment section, 104,114...logical AND gate section, 105...logical OR gate section, 106,116...holding circuit section, 112...power generation output detection section

Claims

1. A clutch state detection device for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a common rotating shaft, and power transmission between the generator and the steam turbine is switched between a connected state and a disconnected state by a clutch, a speed difference detection unit that detects whether a rotational speed difference between the rotational speed of the gas turbine and the rotational speed of the steam turbine is equal to or smaller than a predetermined value; a steam pressure detection unit that detects whether an inlet steam pressure of the steam turbine is equal to or higher than a predetermined pressure; and a determination unit that determines that the clutch is in an engaged state when the speed difference detection unit detects that the rotational speed difference is equal to or less than the predetermined value and the steam pressure detection unit detects that the inlet steam pressure is equal to or more than the predetermined pressure, thereby not determining that the clutch is in an engaged state when the rotational speed difference is equal to or less than the predetermined value during slowing down of the gas turbine or the steam turbine.

2. the speed difference detection unit is configured to detect whether the rotation speed difference is equal to or greater than another predetermined value that is greater than the predetermined value, 2. The clutch state detection device for a single-shaft combined cycle power plant according to claim 1, wherein the determination unit determines that the clutch is in a disengaged state when the speed difference detection unit detects that the rotational speed difference is equal to or greater than the other predetermined value.

3. 3. The clutch state detection device for a single-shaft combined cycle power plant according to claim 1, wherein the determination unit determines that the clutch is in a disengaged state when the speed difference detection unit does not detect that the rotational speed difference is a predetermined value or less and / or when the steam pressure detection unit does not detect that the inlet steam pressure is the predetermined pressure or more.

4. The steam turbine has a high-pressure turbine rotated by high-pressure steam generated in a heat recovery boiler by exhaust gas from the gas turbine, and another turbine rotated by steam having a pressure lower than that of the high-pressure steam, 4. The clutch state detection device for a single-shaft combined cycle power plant according to claim 1, wherein the steam pressure detection unit determines that the inlet steam pressure of the steam turbine is equal to or higher than the specified pressure when it detects that the inlet steam pressure of the other turbine is equal to or higher than a first specified pressure as the specified pressure, or when it detects that the inlet steam pressure of the other turbine is equal to or higher than a first specified pressure as the specified pressure and the inlet steam pressure of the high-pressure turbine is equal to or higher than a second specified pressure as the specified pressure.

5. 5. The clutch state detection device for a single-shaft combined cycle power plant according to claim 4, wherein the other turbine is an intermediate pressure turbine that is rotated by reheated steam obtained by heating the steam discharged by the high pressure turbine.

6. A clutch state detection device for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a common rotating shaft, and power transmission between the generator and the steam turbine is switched between a connected state and a disconnected state by a clutch, a speed difference detection unit that detects whether a rotational speed difference between the rotational speed of the gas turbine and the rotational speed of the steam turbine is equal to or smaller than a predetermined value; a power generation output detection unit for detecting whether or not a power generation output of the generator has increased; and a determination unit that determines that the clutch is in an engaged state when the speed difference detection unit detects that the rotational speed difference is equal to or less than a predetermined value and the power generation output detection unit detects that the power generation output has increased, and thereby does not determine a state in which the rotational speed difference is equal to or less than the predetermined value during slowing down of the gas turbine or the steam turbine, as the clutch being in an engaged state.

7. the speed difference detection unit is configured to detect whether the rotation speed difference is equal to or greater than another predetermined value that is greater than the predetermined value, 7. The clutch state detection device for a single-shaft combined cycle power plant according to claim 6, wherein the determination unit determines that the clutch is in a disengaged state when the speed difference detection unit detects that the rotational speed difference is equal to or greater than the other predetermined value.

8. 8. The clutch state detection device for a single-shaft combined cycle power plant according to claim 6 or 7, wherein the power generation output detection unit calculates a difference between the power generation outputs of the generator at two different points in time, and determines that the power generation output has increased when the difference is equal to or greater than a predetermined output value.

9. A clutch state detection method for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a common rotating shaft, and power transmission between the generator and the steam turbine is switched between a connected state and a disconnected state by a clutch, comprising: a speed difference detection step of detecting whether a rotational speed difference between the rotational speed of the gas turbine and the rotational speed of the steam turbine is equal to or smaller than a predetermined value; a steam pressure detection step of detecting whether or not an inlet steam pressure of the steam turbine is equal to or higher than a predetermined pressure; a determination step of determining that the clutch is in an engaged state when the speed difference detection step detects that the rotational speed difference is equal to or less than the predetermined value and the steam pressure detection step detects that the inlet steam pressure is equal to or more than the predetermined pressure, thereby not determining that the clutch is in an engaged state when the rotational speed difference is equal to or less than the predetermined value during slowing down of the gas turbine or the steam turbine.

10. A clutch state detection method for a single-shaft combined cycle power plant in which a gas turbine, a generator, and a steam turbine are connected by a common rotating shaft, and power transmission between the generator and the steam turbine is switched between a connected state and a disconnected state by a clutch, comprising: a speed difference detection step of detecting whether a rotational speed difference between the rotational speed of the gas turbine and the rotational speed of the steam turbine is equal to or smaller than a predetermined value; a power generation output detection step of detecting whether or not the power generation output of the generator has increased; a determination step of determining that the clutch is in an engaged state when the speed difference detection step detects that the rotational speed difference is equal to or less than a predetermined value and when the power generation output detection step detects that the power generation output has increased, thereby not determining that the clutch is in an engaged state when the rotational speed difference is equal to or less than the predetermined value during slowing down of the gas turbine or the steam turbine.

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