JP3744705B2 - Gas turbine power generation equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas turbine power generation facility for maintaining operation of a power generation facility and securing a power source for an important load when an excessive torque is generated in a generator due to an instantaneous voltage drop or a power failure of a commercial power system.
[0002]
[Prior art]
When an accident occurs in a commercial power system due to lightning or the like, there is a phenomenon in which the voltage of the transmission line is greatly reduced instantaneously. Such a voltage drop is called “instantaneous voltage drop”. In order to secure the power supply of the important load of the factory while minimizing the damage of the power generation equipment, there is a case where a device for detecting an accident at a high speed and disconnecting the commercial power supply system is installed. However, even when such a device is installed, if the disconnection speed is not sufficiently high, the voltage at the power receiving end is greatly reduced instantaneously.
The duration of the instantaneous voltage drop is usually about 1 second or less, and the frequency varies greatly depending on the district. Even if the instantaneous voltage drop is instantaneous and infrequent, it may be severely affected in industries (for example, the semiconductor industry) having factories where voltage changes are not permitted by consumers of high-voltage power reception. Therefore, in such an industry, it is strongly desired to provide a power generation facility in addition to a commercial power source and to stably secure a power source for an important load of a factory even when an instantaneous voltage drop occurs.
[0003]
FIG. 7 is a schematic diagram of a gas turbine power generation facility conventionally used as such a power supply facility. In this figure, 1 is a prime mover such as a gas turbine, 2 is a pinion gear, 3 is a wheel gear, 4 is a shaft coupling, 5 is a generator, and the prime mover 1 is rotationally driven by the prime mover 1. The speed is reduced by the meshing, and the generator 5 is rotationally driven via the shaft coupling 4 to generate power.
[0004]
FIG. 8 is an enlarged view of a portion A in FIG. As shown in this figure, the conventional wheel gear 3 has a configuration in which the central shaft 3a is supported by bearings 3b at both ends, and the shaft coupling 4 includes intermediate members 6a and 6b, shear pins 7 for connecting them, and It consists of a bending element 8, etc., and is connected to the central shaft 3a of the wheel gear 3 and the drive shaft 5a of the generator 5 via the bending element 8, and allows a slight deviation of the shaft center, and a torque exceeding the allowable torque. When acted, the shear pin 7 is cut so that excessive torque does not act on the prime mover 1. Further, in this example, the intermediate member 6a, 6b is supported by the bearing 9, and the rotation of the central shaft 3a and the drive shaft 5a after the shear pin 7 is cut is supported so that each shaft is not damaged. It was.
[0005]
[Problems to be solved by the invention]
However, in the above-described gas turbine power generation facility, when the power generation facility operates in parallel with the system and an instantaneous voltage drop occurs in the system, an excessive electric torque is generated in the generator. Therefore, there was a problem that the shear pin provided to protect the prime mover was damaged. That is, the prime mover has the torsional strength of the axle necessary to transmit its maximum output, and instantaneously allows the transmission of torque several times the rated torque, but the generator short circuit accident, If excessive electrical torque is generated in the generator due to instantaneous voltage drop or power failure on the system side, and its transient response torque exceeds the allowable torque of the prime mover, the shear pin between the prime mover shaft and the generator shaft will break, and recovery There was a problem that took time. In addition, there is a problem that even if the voltage drop is relatively small (10 to 30%), the shear pin may be broken due to accumulation of metal fatigue.
[0006]
The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a gas turbine capable of maintaining the operation of a power generation facility and securing a power source for an important load when a short time excessive torque is generated in a generator due to an instantaneous voltage drop or a power failure. It is to provide power generation facilities. Another object of the present invention is to provide a gas turbine power generation facility that does not require an extended installation length. Still another object is to provide a gas turbine power generation facility capable of returning in a short time without damaging each shaft even when the allowable torque of the transmission shaft is exceeded. Yet another object is to provide a gas turbine power generation facility that does not stop operation even if a relatively small instantaneous voltage drop occurs repeatedly.
[0007]
[Means for Solving the Problems]
Regarding the fluctuation of electric torque when instantaneous voltage drop occurs in the system, the instantaneous maximum generated torque may reach about 6 times the normal, the duration is extremely short, and the average torque with a period of 16-20 msec. It may fluctuate up and down around the center and may return to normal torque in less than 1 second. Therefore, in order to prevent damage to the prime mover such as the gas turbine and maintain the operation of the power generation facility by this instantaneous maximum generated torque, it is necessary to attenuate the excessive electric torque of the generator before transmitting it to the prime mover. . That is, it is only necessary that this short-time fluctuation torque energy can be absorbed by some mechanism. The present invention is based on such new knowledge and ideas.
[0008]
That is, according to the present invention, a gas turbine power generation facility that rotationally drives a generator (5) with a gas turbine (1), comprising power transmission means (10) between the gas turbine and the generator, The transmission means is set so that the strain energy within its elastic limit is larger than the fluctuating torque energy of the generator when the instantaneous voltage drops, and the power transmission means (10) is an intermediate gear (12) that is rotationally driven by a gas turbine. And a shaft coupling (14) that is arranged coaxially with the intermediate gear and connects the intermediate gear and the generator, and the output shaft of the intermediate gear includes a long shaft (13a) positioned at the center and a hollow shaft that surrounds the long shaft (13a) (12a), one end of the long shaft is connected to the hollow shaft and the other end is connected to the shaft coupling, and the combined torsional rigidity GIp of the long shaft and the shaft coupling is sufficiently small. The sum of the strain energy within the elastic limit of the shift and the shaft joint is greater than the torque fluctuation energy of the generator when the instantaneous voltage drop, the gas turbine generator is provided, characterized in that.
[0009]
According to the configuration of the present invention, since the strain energy within the elastic limit of the power transmission means (10) is set larger than the fluctuating torque energy of the generator when the instantaneous voltage drops, the instantaneous maximum generated torque in a short time Is elastically held inside as strain energy, and releases the energy when torque is generated in the reverse direction with a period of 16 to 20 msec. Therefore, the operation of the power generation facility can be maintained without transmitting excessive torque to the gas turbine.
In addition, the torsion spring constant of the long shaft and shaft coupling is set to an appropriate value, the combined torsional rigidity GIp is sufficiently small, and the sum of strain energy within the elastic limit of the long shaft and shaft coupling is By making it larger than the fluctuating torque energy, it is possible to greatly reduce the excessive transmission torque when the instantaneous voltage drop occurs.
[0012]
Furthermore, it is preferable to provide a hydraulic torque limiter (16) between the shaft coupling (14) and the generator (5). This hydraulic torque limiter is often of the type that holds the pressure oil between the inner ring and the outer ring, and when a transient response torque greater than the set torque is applied, the pressure oil is released and the inner ring and the outer ring rotate freely. Thus, it is possible to prevent the shear pin from being cut off due to accumulation of metal fatigue and the accompanying stoppage of the power generation equipment.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is used for a common part in each figure.
FIG. 1 is a partial configuration diagram of a gas turbine power generation facility according to the present invention. In this figure, 12 is an intermediate gear that is rotationally driven by the gas turbine 1 of FIG. 7, and 5a is an input shaft of the generator 5 of FIG. That is, FIG. 1 shows a portion corresponding to part A of FIG. 7, and the gas turbine power generation facility of the present invention is a power generation facility that rotates the generator 5 with the gas turbine 1.
[0014]
As shown in FIG. 1, the gas turbine power generation facility of the present invention includes power transmission means 10 between the gas turbine and the generator. The power transmission means 10 includes a so-called quill shaft 13 and a shaft coupling 14 positioned at the center as an output shaft of the intermediate gear 12. The quill shaft 13 includes a long shaft 13a and a hollow shaft 12a surrounding the long shaft 13a. The hollow shaft 12a is rotatably supported at both ends by bearings 12b. Further, one end (the left end in the figure) of the long shaft 13a is connected and held to the left end portion of the hollow shaft 12a by, for example, a spline, and the other end (the right end in the figure) is rotatably supported by a bearing 12c. And so on.
[0015]
The shaft coupling 14 is arranged coaxially with the intermediate gear 12 as shown in this figure, one end is connected to the long shaft 13a and the other end is connected to the generator 5, and the intermediate gear and the generator are connected to transmit rotational torque. It is like that.
[0016]
Further, a hydraulic torque limiter 16 is provided between the shaft coupling 14 and the generator 5, in this example, between the input shaft 5a of the generator 5 and the coupling member 5b. This hydraulic torque limiter preferably retains pressure oil between the inner ring and the outer ring so that there is no influence due to accumulation of metal fatigue, and the pressure oil is released when a transient response torque greater than the set torque is applied. It is preferable that the inner ring and the outer ring rotate freely with respect to each other.
[0017]
In the power transmission means 10 having the above-described configuration, the strain energy within the elastic limit is set to be larger than the fluctuation torque energy of the generator when the instantaneous voltage drops. In other words, in this example, the combined torsional rigidity GIp of the long shaft 13a and the shaft coupling 14 is sufficiently small, thereby reducing the combined spring constant of the long shaft 13a and the shaft coupling 14, and the elastic limit of the long shaft 13a and the shaft coupling 14 The sum of the distortion energy is set to be larger than the fluctuating torque energy of the generator when the instantaneous voltage drops. That is, by configuring the long shaft 13a to be thin and long, the composite spring constant can be lowered, and the strain energy held inside during torsional deformation can be increased.
Moreover, the shaft coupling 14 of FIG. 1 has a diaphragm part in both ends, and accept | permits the shift | offset | difference of an axial center. Further, a shear pin is not provided in the intermediate portion as in the conventional case, and it is an integral hollow shaft. Similar to the long shaft 13a, this shaft coupling is also made thin and long, so that the strain energy held inside during torsional deformation can be increased. In addition, L1 and L2 in the figure show the case where it is set similarly to the conventional example. Further, the shaft at the intermediate portion of the shaft coupling may be a thin solid shaft instead of the hollow shaft.
[0018]
With the above-described configuration, when a short-time excessive torque is generated in the generator due to a momentary voltage drop or the like, the torsional deformation of the long shaft 13a and the shaft coupling 14 causes the fluctuation torque energy due to the short-time instantaneous maximum generated torque to be distorted. It can be retained elastically as energy, maintain the operation of the power generation facility, and secure a power source for important loads.
In addition, since the long shaft 13a and the hollow shaft 12a have a double configuration, it is possible to avoid the extension of the installation length (for example, L1 and L2 in the figure) due to the adoption of the long shaft 13a. Furthermore, since the hydraulic torque limiter 16 of FIG. 1 can be provided between the input shaft 5a of the generator 5 and the joint member 5b, the installation length can be shortened accordingly. The hollow shaft 12a may be integrated with the wheel gear. Further, in order to avoid resonance between the natural frequency of torsion and the generator rotational speed, an additional mass for adjusting the polar moment of inertia may be attached to the wheel gear or the generator.
[0019]
In addition, even if excessive torque that cannot be sufficiently absorbed by strain energy is applied and the allowable torque of the transmission shaft is exceeded, the use of a hydraulic torque limiter that does not affect metal fatigue prevents damage to each shaft and shortens it. Even if a relatively small instantaneous voltage drop occurs repeatedly, it is possible to prevent the operation from being stopped. Furthermore, even if this hydraulic torque limiter is operated, the inner ring and the outer ring are maintained concentrically, so that damage to each shaft can be essentially prevented. Instead of the hydraulic torque limiter, a torque limiter of another method (for example, an electromagnetic crack) may be used.
[0020]
【Example】
The embodiments of the present invention described above will be described below based on simulation results.
FIG. 2 is a characteristic diagram of the power transmission means of the present invention. This figure shows a case where the voltage drops by 100% due to the instantaneous voltage drop. In this figure, the horizontal axis is the spring constant of the power transmission means 10 and is shown as a ratio to the conventional shaft coupling 4. The vertical axis represents the maximum torque, which is expressed as a ratio with respect to the rated torque in the steady state. The maximum torque in the conventional shaft coupling 4 was about 4 or more for the shaft coupling and about 3.5 or more for the gas turbine output shaft (GT output shaft).
From this figure, it can be seen that the spring constant may be reduced to 1/40 or less of the conventional value in order to be less than the maximum allowable torque of the gas turbine output shaft (approximately 1.8 times the rated torque).
[0021]
FIG. 3 is a configuration diagram of a shaft coupling constituting the power transmission means of the present invention. This shaft coupling 14 'has a diaphragm part at both ends, like the shaft coupling 14 of FIG.
With the shaft coupling 14 ′ having the configuration shown in FIG. 3, the spring constant can be set up to about 1/20 without changing the length of the conventional shaft coupling 4. However, by itself, the target cannot be reduced to 1/40 or less of the target, but in the present invention, the target can be achieved by combining with the quill shaft 13.
[0022]
FIG. 4 is a configuration diagram of another shaft coupling similar to the shaft coupling 14 constituting the power transmission means of the present invention. As shown in this figure, the spring constant can be reduced to 1/40 or less of the conventional value by making L2 longer than the shaft coupling 14 of FIG. However, in this case, the total length is longer than when combined with the quill shaft 13.
[0023]
FIG. 5 is a simulation result showing an embodiment of the present invention, (A) shows a conventional example, and (B) shows the configuration of the present invention shown in FIG. 1 (when the spring constant is 1/50 of the conventional). ing. In each figure, the horizontal axis represents time, and the vertical axis represents torque when the voltage drops 100% due to instantaneous voltage drop. The broken line in the figure is the electric torque of the generator, the thick solid line is the shaft coupling, and the thin solid line is the transient response torque of the gas turbine output shaft.
From the comparison of FIG. 5, in the conventional example (A), the maximum value of the GT output shaft is about 3.5 or more, whereas in the example of FIG. , You can see that the goal has been fully achieved.
Further, from FIG. 5 (A), the instantaneous maximum generated torque reaches about 6 times the normal torque, but its duration is extremely short, fluctuates up and down around the average torque at a period of about 20 msec, and about 0.5 It can be seen that after a second, the torque returns to normal. Therefore, the fluctuation torque energy of the excessive electric torque that acts for at least about 20 msec is elastically held in the inside as strain energy due to the torsional deformation of the long shaft 13a and the shaft coupling 14 described above. Operation can be maintained and a power source for important loads can be secured.
[0024]
6A and 6B show another simulation result showing the embodiment of the present invention. FIG. 6A shows the case where the spring constant is 1/20 of the conventional case, and FIG. 6B shows the case where it is 1/40.
From this figure, the maximum value of the GT output shaft is about 1.9 in (A) and about 1.6 in (B).
That is, from (A), it can be seen that the target cannot be achieved only by the configuration of the shaft coupling shown in FIG. 3, but this can be easily achieved by combining with the quill shaft 13. Further, the spring constant 1/40 in (B) is possible by extending the length as shown in FIG. 4, but in order to avoid the extension of the installation length, a combination with the quill shaft 13 is necessary. I know that there is.
[0025]
Note that the present invention is not limited to the above-described embodiments and examples, and can be variously modified without departing from the gist of the present invention.
[0026]
【The invention's effect】
As described above, the gas turbine power generation equipment of the present invention is provided with a quill shaft in the speed reducer between the prime mover shaft and the generator shaft, and further reduces the torsion spring constant of the shaft coupling to reduce the basic torque of the excessive torque generated in the generator. The natural frequency of the prime mover-generator shaft system that responds to the frequency is lower than the fundamental frequency of the electric torque, and the separation length is sufficiently increased. With this configuration, even when a relatively large (50 to 100%) instantaneous voltage drop occurs in the system, it is possible to reduce the transient response torque due to the electric torque generated in the generator below the maximum allowable transmission torque of the prime mover. Become.
Therefore, even if excessive electrical torque is generated in the generator due to an instantaneous voltage drop in the system due to lightning, etc., it is possible to maintain the operation of the power generation equipment and secure a power source for the important load of the factory where the power generation equipment is installed. It becomes possible.
[0027]
In other words, the gas turbine power generation facility of the present invention can maintain the operation of the power generation facility and secure a power source for an important load when a short-time excessive torque is generated in the generator due to an instantaneous voltage drop or the like. There is no need to extend the length, and even if the allowable torque of the transmission shaft is exceeded, each shaft can be restored in a short time without being damaged, and even if a relatively small instantaneous voltage drop occurs repeatedly, the operation will be stopped. Excellent effects such as no
[Brief description of the drawings]
FIG. 1 is a partial configuration diagram of a gas turbine power generation facility according to the present invention.
FIG. 2 is a characteristic diagram of the power transmission means of the present invention.
FIG. 3 is a configuration diagram of a shaft coupling constituting the power transmission means of the present invention.
FIG. 4 is a configuration diagram of another shaft coupling constituting the power transmission means of the present invention.
FIG. 5 is a simulation result showing an example of the present invention.
FIG. 6 is another simulation result showing the embodiment of the present invention.
FIG. 7 is a schematic diagram of a conventional gas turbine power generation facility.
8 is an enlarged view of a portion A in FIG.
[Explanation of symbols]
1 prime mover (gas turbine)
2 Pinion gear 3 Wheel gear 3a Center shaft 3b Bearing 4 Shaft coupling 5 Generator 5a Drive shaft (input shaft)
5b Joint member 6a, 6b Intermediate member 7 Shear pin 8 Deflection element 9 Bearing 10 Power transmission means 12 Intermediate gear 12a Hollow shaft 12b Bearing 12c Bearing 13 Quill shaft 13a Long shaft 14, 14 'Shaft coupling 16 Hydraulic torque limiter

Claims (2)

A gas turbine power generation facility that rotationally drives a generator (5) with a gas turbine (1), comprising power transmission means (10) between the gas turbine and the generator, the power transmission means being within its elastic limit. Is set to be larger than the fluctuating torque energy of the generator at the time of instantaneous voltage drop ,
The power transmission means (10) includes an intermediate gear (12) that is rotationally driven by a gas turbine, and a shaft coupling (14) that is arranged coaxially with the intermediate gear and connects the intermediate gear and the generator.
The output shaft of the intermediate gear is composed of a long shaft (13a) positioned at the center and a hollow shaft (12a) surrounding the long shaft (13a). One end of the long shaft is connected to the hollow shaft and the other end is connected to the shaft coupling. The combined torsional rigidity GIp of the shaft and shaft coupling is sufficiently small, so that the sum of the strain energy within the elastic limit of the long shaft and shaft coupling is set to be larger than the fluctuation torque energy of the generator when the instantaneous voltage drops A gas turbine power generation facility. Between the shaft coupling (14) and the generator (5), the gas turbine power generation facility according to claim 1, characterized in that it comprises a hydraulic torque limiter (16).

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