Dual-purpose integrated gear for hybrid train applications

Abstract

A hybrid train system is disclosed, which includes at least one gas turbine for driving a load and an electric machine unit also connected to the load, a clutch is provided between the gas turbine and the load, and an integrated reduction gear unit is interposed between the load and the electric machine unit to accommodate different operating speeds.

Description

[Technical field]

[0001] The present disclosure relates to a dual purpose integrated gear for hybrid train applications for a hybrid configuration train system comprising an electric motor / generator, a compressor shaft line, and a reduction gear unit integrated in the compressor shaft line. [Background technology]

[0002] Gas turbines are often used to provide torque to a load, such as a compressor, for example in the field of liquefied natural gas, and generally in the oil and gas industry. The gas turbine is typically connected to the load, such as the aforementioned compressor, pump, or any rotating equipment, via a rotating shaft or a rotating transmission assembly.

[0003] More specifically, with reference to Liquefied Natural Gas (LNG) processing, LNG is liquefied by a liquefaction process in which natural gas is cooled using a refrigeration cycle, resulting in a liquid that can be stored and transported.

[0004] To cool the LNG, a refrigerant is cooled by a compressor, which is then condensed and expanded to remove heat from the natural gas flowing in a heat exchanger. The compressor is typically driven by a gas turbine.

[0005] Recently, electric machines are also included in the layout. Configurations in which there is a gas turbine, a load and an electric machine along a shaft line are usually known and are called hybrid train configurations, hybrid train systems, hybrid turbo-compressor trains or simply hybrid trains. In such configurations, the electric machine can act as a helper or other electric motor, for example to alternatively provide torque to a load (e.g. a compressor) when the gas turbine cannot operate, or to directly provide torque to the gas turbine, for example during the start-up phase.

[0006] A known configuration includes a gas (or steam) turbine connected in series and a load, e.g., a compressor, connected to the gas turbine by a transmission assembly. Specifically, the transmission assembly includes a first transmission shaft having one end connected to the gas turbine, a second transmission shaft having one end connected to the load, and a clutch connecting the first transmission shaft and the second transmission shaft. The clutch operates to mechanically decouple or couple the two transmission shafts to transmit power generated by the gas turbine to the load. The hybrid train system also includes an electric machine connected to the load.

[0007] The electric machine can also operate as a generator, for example when excess power is produced by the gas turbine over that normally required by the load, in which case the power is converted by the electric machine into electrical energy and then injected, for example, into a public power grid.

[0008] Since gas turbines and electric machines typically have different operating speeds, the issue of transmission torque arises when designing a hybrid train. Specifically, the electric machine can be selected within the base solution to operate at 1500 or 1800 RPM (for 4-pole machines), or 3000 / 3600 RPM (for 2-pole machines). This increases supplier availability and potential commonality with pure power generation applications.

[0009] Typically, the electric machine has a lower operating speed range than the gas turbine. It is a hybrid train design problem to match the speed of the electric machine to the speed of the gas turbine. In prior art hybrid train systems, the electric motor is usually necessarily over-designed. However, this means higher cost, weight, and increased footprint. Furthermore, there is a coupling problem between the electric motor and the load, where a bidirectional transmission of torque at variable speed is required to enable the transmission of torque to drive the load when the electric machine operates as a motor, or to be driven by the load when the electric machine operates as a generator.

[0010] This represents a rotor dynamic limit and design bottleneck for the mechanical coupling between the load and the electric machine. Therefore, an improved torque transfer connection for electric machines would be welcomed in the art. More generally, it is desirable to provide a torque transfer mechanism that allows a torque compatible transfer between the electric machine (low speed) and the load, which is directly connected to the gas turbine and operates at higher speeds, especially when the electric machine operates as a motor, i.e., transfers torque to the load. Summary of the Invention

[0011] In one aspect, the subject matter disclosed herein relates to a hybrid train system having a load, such as a compressor or pump driven by a torque, and a gas turbine for generating a drive torque for driving the load. The gas turbine operates at a first rotational speed belonging to a first operating rotational speed range. The gas turbine is also operatively connected to the load. The hybrid train system also comprises an electric machine unit mechanically connected to the load and a rotating shaft mechanically connecting the load and the electric machine unit. The electric machine unit is capable of operating at a second rotational speed belonging to a second operating rotational speed range, the second speed being lower than the first speed of the gas turbine. The hybrid train system also comprises an integrated reduction gear unit, such as a planetary gear type, connected to the electric machine unit and the rotating shaft. The integrated reduction gear unit is capable of transmitting torque from the electric machine unit to the load and vice versa. Furthermore, the integrated reduction gear unit is adapted to match the first rotational speed of the gas turbine with the second rotational speed of the electric machine unit.

[0012] In another aspect of the subject matter disclosed herein, an integrated reduction gear unit includes a central sun wheel having a high speed flange mechanically connectable to a rotating shaft, an internal gearing having internal teeth, a set of star wheels disposed within the internal gearing and engaging with the internal teeth of the internal gearing, a low speed flange mechanically connected to the internal gearing and the electric machine unit, and a coupling connecting the central sun wheel and the rotating shaft for torque transmission.

[0013] A further aspect of the present disclosure is directed to the fact that the hybrid train system includes a mechanical oil pump mechanically connected to the integrated reduction gear unit for operating the integrated reduction gear unit, the mechanical oil pump including an upper coupling flange and a lower coupling flange for coupling the mechanical oil pump to the integrated reduction gear unit.

[0014] In another aspect of the subject matter disclosed herein, the hybrid train system includes a torque limiter device coupled to the low-speed flange, the torque limiter device capable of decoupling the electric machine unit from the rotating shaft if excessive torque is transmitted through the rotating shaft. The torque limiter device may include a shear bolted joint support bearing, a collar surrounding the shear bolted joint support bearing, the collar being adapted to be fitted and positioned on the low-speed flange, and one or more shear pins, each having a shear neck and positioned to connect the collar and the low-speed flange, the shear pins adapted to break if the torque transmitted through the rotating shaft exceeds a pre-determinable threshold. In another embodiment, the low-speed flange may have a flat surface. The collar may have a flat surface recessed to fit the flat surface of the low-speed flange. The collar may have one or more seats obtained on the flat surface. The torque limiter device also includes one or more axial springs, each received in a respective seat, and the axial springs are capable of separating the collar and the low-speed flange in the event that the shear pin breaks.

[0015] In another aspect of the subject matter disclosed herein, the electric mechanical unit is configured to operate as an electric motor to transmit torque to a load and as a generator to receive torque from the load, and is connected to an electric power grid such that when the electric mechanical unit operates as an electric motor, the electric power grid supplies power to the electric mechanical unit, while when the electric mechanical unit operates as a generator, the electric mechanical unit injects power into the electric power grid. [Brief description of the drawings]

[0016] A complete understanding of the disclosed embodiments of the present invention and many of the attendant advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which: [Figure 1]FIG. 1 is a schematic diagram of a hybrid train system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an integrated reduction gear unit of a planetary gear type. [Diagram 3] FIG. 3 illustrates an embodiment of coupling an electric machine unit to a rotating shaft of a hybrid train system according to embodiment 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 5 is a diagram showing a torque limiter device integrated into the hybrid train system of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Gas turbines are used to drive loads, such as compressors, connected to a shaft. In recent years, so-called hybrid train systems, which also integrate electric machines, have become widespread on the market. Gas turbines and electric motors are usually not interchangeable, since they operate at different speeds.

[0018] To avoid designing an oversized electric machine, according to one aspect, the present subject matter is directed to the integration of an integrated reduction gear unit that can bidirectionally match the operating speed range of the gas turbine to the operating speed range of the electric machine while transmitting torque.

[0019] Referring now to the drawings, Figure 1 shows a hybrid train system 1 according to embodiment 1. The hybrid train system 1 comprises a gas turbine 2 and a load 3 driven by the gas turbine 2. The gas turbine 2 operates at a first speed, which may typically range from 65% to 105% of a nominal speed.

[0020] The gas turbine 2 comprises a gas compressor 21 capable of compressing air from the environment, which is delivered to a combustor 22. In the combustor 22, fuel is added to the air flow to form a fuel / air mixture which is ignited. Combustion gases generated in the combustor are delivered to a high-pressure turbine 23, in which they are partially expanded to generate mechanical power. The mechanical power generated by the high-pressure turbine 23 is used to drive the gas generator compressor 21.

[0021] The load 3 is connected to the gas turbine by a transmission assembly 4. Specifically, the transmission assembly 4 includes a first transmission shaft 41 having one end connected to the gas turbine 2, a second transmission shaft 42 having one end connected to the load 3, and a clutch 43.

[0022] In the illustrated layout of the hybrid train system 1, the clutch 43 comprises clutch discs, i.e. a first clutch disc 431 and a second clutch disc 432 connected to the first transmission shaft 41 and the second transmission shaft 42, respectively. The clutch discs 431 and 432 are engageable for power transmission. The clutch 43 is accommodated in a housing 44.

[0023] The hybrid train system 1 also comprises an electric machine unit 6 mechanically connected to the load 3 by a rotating shaft 5. The electric machine unit 6 can either operate as an electric motor to provide torque to the load 3 or as a generator to convert torque received via the rotating shaft 5 into electrical power.

[0024] In the illustrated embodiment, the load 3 is a compressor, but in other embodiments the load may be a different load, such as a pump.

[0025] The hybrid train system 1 also comprises an integrated reduction gear unit 7 connected to the rotating shaft 5 and to the electric machine unit 6 .

[0026] The integrated reduction gear unit 7 is adapted to adjust the operating speed range of the electric machine unit 6, such that the electric machine unit 6 can operate in a second operating speed range lower than the operating speed of the gas turbine 2. In general, the electric machine unit 6 can operate at 1,500-1,800 rpm (for a four pole machine) or 3,000-3,600 rpm (for a two pole machine).

[0027] The integrated reduction gear unit 7 can operate bidirectionally, i.e. it can reduce or increase the speed between the points to which it is connected, as will be explained in more detail below. In particular, when the electric machine unit 6 operates as an electric motor, i.e. as described above, when it supplies a torque to the load 3, the integrated reduction gear unit 7 increases the speed on the rotating shaft 5 in order to drive the load unit 6. In other words, it increases the rotational speed from the second operating speed range to a speed in the first operating speed range, so that the rotating shaft 5 can transmit a torque adapted to drive the load 3. Alternatively, when the electric machine unit 6 operates as a generator, the electric machine unit 6 converts the torque received via the rotating shaft 5 and generated by the gas turbine 2 into electrical energy, which can be injected, for example, into the power grid G ​​or can be used to charge a battery pack or to drive other loads. In this case, the integrated reduction gear unit 7 reduces a speed belonging to the first operating speed range to a speed belonging to the second operating speed range, the second speed being lower than the first speed, as described above.

[0028] In this embodiment, the rotation of the rotating shaft 5 is always in the same direction, which can be clockwise or counterclockwise, and the electric machine unit 6 operates either as a motor or as a generator.

[0029] The relationship between torque and speed is:

[0030]

number

[0031] An example of an integrated reduction gear unit 7 is shown in Figure 2, which is a planetary type gear and comprises a central sun wheel 71 with a high speed flange 72 connectable to a high speed source, i.e. in this case to the load unit 6 via the rotating shaft 5. The load unit 6 mainly operates at the speed of the gas turbine 2 which, as mentioned above, is higher than the speed of the electric machine unit 6.

[0032] The integrated reduction gear unit 7 also comprises an internal gearing 73, also called annulus, having internal teeth (not shown). The internal gearing 73 rotates according to arrow R during operation. Located within the internal gearing 73 are a set of star wheels (collectively indicated at 74) which are mechanically connected to a low speed flange 75 and connected to the electromechanical unit 6. The set of star wheels 74 engage with the internal teeth of the internal gearing 73.

[0033] The integrated reduction gear unit 7 of the planetary gear type is bidirectional, i.e. capable of transmitting and converting torque and speed in both directions, allowing the electric machine unit 6 to operate both as a motor and as a generator in the second speed range.

[0034] In other embodiments, other types of integrated reduction gear unit 7 can be used.

[0035] Generally, in a typical customer plant, the limited space available makes it essential to minimize the train footprint and its impact on the auxiliary equipment. When the original turbo compressor installation is driven by a high speed gas turbine 2, this means choosing a high speed variable speed drive system (VSDS) (limited available supplier spectrum, considering also active front-end variable frequency drive (VFD)). At the same time, conventional gearing leads to a very large train footprint.

[0036] 3 and 4, another embodiment of coupling an electromechanical unit 7 to a rotating shaft 5 by rotational speed adaptation is shown. In particular, an epicycloidal cantilever integrated reduction gear unit 7 is shown.

[0037] In this case, the reduction on the VSDS is achieved through epicycloidal gears, cantilever on the electric machine, or pedestal type which is a VSDS active front end type, and the planetary gears shall be designed to withstand bidirectional torque and variable speed operation.

[0038] In particular, and with continued reference to Figure 3, the electric machine unit 6 is shown to comprise an electric machine 61, operable as either an electric motor or a generator as previously described, and a cooler 62 disposed on the electric machine 61 for extracting heat during its operation. The electric machine 61 also comprises an electrical connection, generally indicated with the reference numeral 611, and a coupling flange 612 having an associated coupling crown 613, by which the electric machine 61 is connected to an integrated reduction gear unit 7, which in the illustrated embodiment is of the planetary gear type, but which may be of any other type. The coupling crown 613 is mechanically coupled to a low speed flange 75 of the integrated reduction gear unit 7.

[0039] Finally, with further reference to Figure 3, the integrated reduction gear unit 7 also comprises a coupling 76 connecting the central sun wheel 71 and the rotating shaft 5 for torque transmission. The coupling comprises a body 761 and a connection flange 762 connected to the body. The connection flange 762 has a number of holes 763 for connection by a number of bolts. Also visible is an inspection cover 764 to allow inspection inside the body in case of malfunction or problems with torque transmission.

[0040] In the illustrated embodiment, a mechanical oil pump 8 is also provided that is mechanically connected to the integrated reduction gear unit 7. Specifically, one wheel of the integrated reduction gear unit 7 is used to operate the mechanical oil pump 8. The mechanical oil pump 8 includes an upper connecting flange 81 and a lower connecting flange 82 for connecting the mechanical oil pump 8 to the integrated reduction gear unit 7.

[0041] In one embodiment, the mechanical pump 8 may be driven by a kinetic chain (not shown), for example comprising an auxiliary shaft connected to the pump 8, one toothed wheel keyed to the auxiliary shaft, and one or more transmission means, such as a toothed wheel, connecting the toothed wheel and thus the auxiliary shaft to the low speed flange 75, or generally to a rotating part of the integrated reduction gear unit 7.

[0042] Typically, mechanical oil pumps are provided in hybrid train systems, but they are not integrated into the system itself, but are merely located near the system, increasing the overall footprint of the plant. As can be seen, the integration of the mechanical oil pump 8 allows the size of the hybrid train system 1 to be reduced.

[0043] The epicycloid gear not only allows a mechanical oil pump to be fitted, providing benefits in terms of reducing the footprint of the lube oil console as described above, but also allows a torque limiter device (TLD) to be fitted to limit the torque coming from the electric machine, providing benefits in shaft line design (e.g. couplings).

[0044] Specifically, referring now to FIG. 4, a partial longitudinal cross-section of the high speed flange 72 is shown. Referring now to FIG. 5, the torque limiter device 9 is coupled to the low speed flange 75. In particular, it can be seen that the torque limiter device 9 comprises a shear bolted support bearing 91 having a centering bolt 92 for centering the position of the torque limiter device 9 and the low speed flange 75. The torque limiter device 9 also comprises a collar 92 surrounding the shear bolted support bearing 91. The collar 92 has a flat surface 93 intended to match a corresponding flat surface 751 of the low speed flange 75. One or more shear pins 94 are disposed through both the collar 92 and the low speed flange 75. Each of the shear pins 94 has an associated shear neck 941. The shear pins 94 connect the collar 92 and the low speed flange 75. Specifically, the shear pin 94 maintains alignment between a flat surface 93 of the collar and a flat surface 751 of the low speed flange 75. Finally, the collar 92 has one or more seats 931 obtained on the flat surface 93, and the torque limiter device 9 includes a set of axial springs 95, each of which is preloaded and positioned within an associated seat 921. The axial springs 95 are capable of separating the collar 92 and the low speed flange 75 in the event of failure of the shear pin 94.

[0045] In other embodiments, other types of torque limiting devices may be installed, such as, for example, a torque clocker type.

[0046] The hybrid train system 1 described above operates as follows.

[0047] When the gas turbine 2 operates, torque can be transmitted by the clutch 43 to the load 3, which in the present case is the compressor as mentioned above. The two clutch disks 431 and 432 of the clutch 43 can be disengaged, in which case no torque is transmitted to the load 3. When the clutch disks 521 and 522 are engaged, the torque generated in the gas turbine 2 can be transmitted from the gas turbine 2 to the load 3.

[0048] In case of excess torque, the electric machine unit 6 operates as a generator: the rotating shaft 5 can thus transmit the excess torque to the electric machine unit 6, which is converted into electrical energy and, for example, injected into the power grid G.

[0049] The rotating shaft 5 rotates at a speed belonging to a first operating speed range, i.e. at the operating speed of the gas turbine 2, which is typically about 10,000 rpm or more. As mentioned above, such a rotational speed is much greater than the operating speed of a typical electric machine unit 6 (which, as mentioned above, typically rotates at an operating speed in the range of 1,500-3,600 rpm).

[0050] The integrated reduction gear unit 7, which receives torque from the rotating shaft 5 via the high speed flange 72, reduces the speed of the rotating shaft 5, i.e. a speed belonging to a first operating range, by means of an internal gearing 73 and a star wheel 74. The speed is then reduced from the (higher) operating speed of the gas turbine 2 to the (lower) operating speed of the electric machine unit 6, i.e. a speed in a second operating speed range, so that the electric machine unit 6 is driven by the low speed flange 75. At the same time, the gears of the integrated reduction gear unit 7 operate the oil pump 8, which pumps oil and lubricant throughout the hybrid train system 1.

[0051] The integrated reduction gear unit 7 is a passive device and can be affected by a torque peck or similar malfunction. In this case, the torque limiter device 9 protects the hybrid train system 1. Indeed, in normal operation, the shear pins 94 of the torque limiter device 9 are subjected to shear forces. When the transmitted torque causes a force that exceeds the shear strength of the pins, i.e. a certain shear strength that can be preset by appropriate design, the shear pins 94 break along the shear neck 941 of each shear pin 94, thus mechanically decoupling the electric machine unit 6 from the rotating shaft 5 and thus from the gas turbine 2 and the load 3.

[0052] The axial spring 95 also releases potential energy stored therein to safely isolate the low speed flange 75 from the shear bolted support bearing 91 of the torque limiter device 9 and therefore from the rotating shaft 5 .

[0053] In contrast, when the electric machine unit 6 operates as an electric motor, e.g. as a helper, to drive the compressor 3, the (lower) operating speed generated by the electric machine unit 6 to transmit power (and therefore torque) to the load 3 is increased by the integrated reduction gear unit 7, which therefore operates bidirectionally. The electric machine unit 6 receives power from the power grid G.

[0054] In this case, as well as in the case of a torque peak or any other problem on the rotating shaft 5 , the torque limiter device 9 decouples the electric machine unit 6 from the rotating shaft 5 and thus from the gas turbine 2 and the load 3 .

[0055] An advantage of the present disclosure relates to an enhanced VSDS supplier spectrum, with clear commercial benefits.

[0056] Another advantage of the present disclosure is that the integrated gear design can be used for both pure power generation or hybrid applications. Additionally, the integrated gear can be equipped with a torque limiter device to limit excess torque coming from the electric machine, achieving rotor dynamic benefits for both the electric machine and compressor design.

[0057] While aspects of the invention have been described in terms of various specific embodiments, it will be apparent to those skilled in the art that many modifications, changes, and omissions are possible without departing from the spirit and scope of the claims. In addition, unless otherwise specified herein, the order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments.

[0058] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided as an explanation of the present disclosure, not as a limitation of the disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the scope or spirit of the disclosure. References throughout this specification to "one embodiment" or "an embodiment" or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the disclosed subject matter. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout this specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0059] When presenting elements of various embodiments, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be non-exclusive and mean that there may be additional elements other than the listed elements.

Claims

1. A hybrid train system (1), comprising: A load (3) driven by a torque; a gas turbine (2) for generating a drive torque for driving the load (3), the gas turbine (2) operating at a first rotational speed within a first operating rotational speed range and operably connected to the load (3); an electromechanical unit (6) mechanically connected to the load (3); a rotating shaft (5) mechanically connecting the load (3) and the electric machine unit (6); Including, the electric machine unit (6) is capable of operating at a second rotational speed within a second operating rotational speed range, the second speed being lower than the first speed of the gas turbine (2); The hybrid train system (1) further comprises an integrated reduction gear unit (7) connected to the electric machine unit (6) and the rotating shaft (5); said integrated reduction gear unit (7) being capable of transmitting torque from said electric machine unit (6) to said load (3) and vice versa; 1. A hybrid train system (1), characterized in that the integrated reduction gear unit (7) is adapted to match the first rotational speed of the gas turbine (2) and the second rotational speed of the electric machine unit (6).

2. 2. The hybrid train system (1) according to claim 1, wherein the integrated reduction gear unit (7) is of the planetary gear type.

3. The integrated reduction gear unit (7) comprises: a central sun wheel (71) having a high speed flange (72) mechanically connectable to said rotating shaft (5); an internal gear ring (73) having internal teeth; a set of star wheels (74) disposed within the internal gear ring (73) and engaging with the internal teeth of the internal gear ring (73); a low speed flange (75) mechanically connected to the inner gear ring (73) and to the electric machine unit (6); a coupling (76) connecting said central sun wheel (71) and said rotating shaft (5) for torque transmission; The hybrid train system (1) according to claim 2, comprising:

4. a mechanical oil pump (8) mechanically connected to the integrated reduction gear unit (7) for operating the integrated reduction gear unit (7); the mechanical oil pump (8) comprises an upper connecting flange (81) and a lower connecting flange (82) for connecting the mechanical oil pump (8) to the integrated reduction gear unit (7); A hybrid train system (1) according to claim 2 or 3.

5. 5. The hybrid train system (1) of claim 3 or 4, further comprising a torque limiter device (9) coupled to the low speed flange (75), the torque limiter device (9) being capable of decoupling the electric machine unit (6) from the rotating shaft (5) if excessive torque is transmitted through the rotating shaft (5).

6. The torque limiter device (9) A shear bolted support bearing (91); a collar (92) surrounding the shear bolted support bearing (91), the collar (92) being fitted and positioned on the low speed flange (75); one or more shear pins (94), each having a shear neck (941), arranged to connect the collar (92) and the low speed flange (75), the shear pins (94) adapted to break if a torque transmitted through the rotating shaft exceeds a predeterminable threshold; The hybrid train system of claim 5 .

7. The low speed flange (75) has a flat surface (751); The collar (92) has a flat surface (93) that is recessed to fit over the flat surface (751) of the low speed flange (75); said collar (92) having one or more seats (931) obtained on said flat surface (93); 7. The hybrid train system (1) of claim 6, wherein the torque limiter device (9) comprises one or more axial springs (95), each axial spring (95) housed in one respective seat (931), and the axial springs (95) are capable of separating the collar (92) and the low speed flange (75) in the event that the shear pin (94) breaks.

8. the first operating rotational speed range of the gas turbine (2) is comprised between 3,000 rpm and 12,000 rpm; The hybrid train system (1) according to any one of claims 1 to 7, wherein the second operating rotational speed range of the electric machine unit (6) is comprised between 1,500 rpm and 1,800 rpm, or between 3,000 rpm and 3,600 rpm.

9. a transmission assembly (4) connecting the load (3) and the gas turbine (2); The transmission assembly (4) comprises: a first transmission shaft (41) connected at one end to the gas turbine (2); a second transmission shaft (42) connected at one end to the load (3); a clutch (43) having a first clutch disc (431) connected to the first transmission shaft (41) and a second clutch disc (432) connected to the second transmission shaft (42), the first clutch disc (431) and the second clutch disc (432) being engageable for power transmission; A hybrid train system (1) according to any one of claims 1 to 8, comprising:

10. The hybrid train system (1) according to any one of claims 1 to 9, wherein the electric machine unit (6) is configured to operate as an electric motor to transmit torque to the load (3) and to operate as a generator to receive torque from the load (3).

11. 11. The hybrid train system (1) of claim 10, wherein the electric machine unit (6) is connected to the power grid (G), and when the electric machine unit (6) operates as an electric motor, the power grid (G) supplies power to the electric machine unit (6), whereas when the electric machine unit (6) operates as a generator, the electric machine unit (6) injects power into the power grid (G).

12. The hybrid train system (1) according to any one of claims 1 to 11, wherein the load (3) is a compressor or a pump.

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