Power generation system shaft system with phase modulation function and working condition switching method

Abstract

The invention discloses a power generation system shafting with a phase modulation function and a working condition switching method.The shafting comprises a high-pressure cylinder, a synchronous motor, a second SSS clutch and a medium-low pressure cylinder, the shafting of the high-pressure cylinder is connected with the shafting at one end of a gearbox, and the shafting at the other end of the gearbox is connected with the shafting of the first SSS clutch; the first SSS clutch, the synchronous motor, the second SSS clutch and the medium-low pressure cylinder are coaxially connected in sequence; the end, connected with the high-pressure cylinder, of the first SSS clutch is an input end, and the end, connected with the synchronous motor, of the first SSS clutch is an output end. The end, connected with the medium-low pressure cylinder, of the second SSS clutch is an input end, and the end, connected with the synchronous motor, of the second SSS clutch is an output end. According to the system, the power transmission path can be flexibly adjusted under different working conditions, the synchronous motor is made to operate as a generator or a motor by controlling connection and disconnection of the SSS clutch, support for phase modulation of a photo-thermal power station or a Carnot cell fused salt energy storage power station is achieved, and the problem that an existing photo-thermal power station does not have the phase modulation function is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power stations, and in particular relates to a shaft system of a power generation system with a phase adjustment function and a working condition switching method. Background Art

[0002] With the rapid development of renewable energy power generation, problems such as low inertia, overvoltage, and broadband oscillation of high-proportion renewable energy are prominent, hindering the expansion of renewable energy power generation. As a basic regulating power source, CSP power station has the dual functions of peak-shaving power source and energy storage, which can provide better long-term peak-shaving capability for the power system. Rotating mechanisms such as synchronous motors and steam turbines also provide rotational inertia for the power grid. However, since the shaft system of the steam turbine and synchronous motor of the CSP power station cannot be separated, the CSP power station does not have the ability of reactive power compensation, which makes the function of the CSP power station unable to be further exerted.

[0003] my country's solar thermal power stations or Carnot battery molten salt energy storage power stations usually use 50MW-class steam turbines as the prime mover for power generation. Since the steam quality generated by the solar thermal power station or Carnot battery molten salt energy storage power station is low, the power generation efficiency of the 50MW-class steam turbine designed according to the existing thermal power generation is low. Therefore, the current solar thermal power station generally adopts a dual-axis, dual-speed design method. Although this shaft system design can significantly improve the relative internal efficiency of the steam turbine, it causes the solar thermal power station to lack the phase adjustment function.

[0004] Publication No. CN117811108A and Publication No. CN109681278A both propose using an SSS clutch to enable the power generation system to have a phase adjustment function. However, on the one hand, their power generation systems are all single-shaft, single-speed designs, which will cause the problem of low power generation efficiency for the application of 50MW units; on the other hand, the existing technology requires shutdown and bearing replacement during the process of switching working conditions, which makes phase adjustment difficult. Summary of the invention

[0005] The purpose of the present invention is to provide a power generation system shaft system and an operating condition switching method with phase adjustment function. On the one hand, it is used to solve the technical defect of the prior art that the solar thermal power station does not have the phase adjustment function; on the other hand, it is used to solve the technical defect that the prior art needs to shut down and replace bearings during the operating condition switching process, which makes phase adjustment difficult.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, a shaft system of a power generation system with a phase adjustment function is provided, comprising: a high-pressure cylinder, a synchronous motor, a second SSS clutch, and a medium- and low-pressure cylinder, wherein the shaft system of the high-pressure cylinder is connected to the shaft system at one end of a gear box, and the shaft system at the other end of the gear box is connected to the shaft system of the first SSS clutch;

[0008] The first SSS clutch, the synchronous motor, the second SSS clutch and the medium and low pressure cylinders are coaxially connected in sequence;

[0009] Wherein, the end of the first SSS clutch connected to the high-pressure cylinder is the input end, and the end connected to the synchronous motor is the output end;

[0010] The end of the second SSS clutch connected to the medium and low pressure cylinders is an input end, and the end connected to the synchronous motor is an output end.

[0011] In a second aspect, a method for switching shaft system operating conditions of a power generation system with a phase adjustment function is provided, when switching from a power generation operating condition to a phase adjustment operating condition, comprising:

[0012] The loads of the high-pressure cylinder and the medium- and low-pressure cylinders are reduced, and the power control is switched to the speed control, so that the speeds of the high-pressure cylinder and the medium- and low-pressure cylinders are maintained at 7255 and 3000 r / min, respectively;

[0013] The synchronous motor is switched from a generator mode to a motor mode through excitation control, and the synchronous motor is kept at a speed of 3000 r / min;

[0014] The speed of the high-pressure cylinder is reduced to 7200-7250r / min, and the speed of the medium- and low-pressure cylinders is reduced to 2950-2980r / min, so that the first SSS clutch and the second SSS clutch begin to separate, and the synchronous motor is separated from the high-pressure cylinder and the medium- and low-pressure cylinders respectively;

[0015] After separating the synchronous motor, switch to phase-adjusting operation, so that the speed of high-pressure cylinder and medium- and low-pressure cylinders is reduced to the cranking speed, with less steam and reactive power, and in hot standby state.

[0016] Furthermore, when switching from the phase adjustment mode to the power generation mode, it includes:

[0017] The synchronous motor is controlled through excitation to maintain the speed of the synchronous motor at 3000r / min;

[0018] The speed of the high-pressure cylinder is increased to 7260-7300 r / min and engaged with the first SSS clutch, and then the high-pressure cylinder is connected to the synchronous motor. During the engagement of the first SSS clutch, the active power absorbed by the synchronous motor from the power grid is gradually reduced to keep the speed of the synchronous motor unchanged.

[0019] After connecting the high-pressure cylinder to the synchronous motor, switch the synchronous motor from the motor mode to the generator mode, and restore the speed of the high-pressure cylinder to 7255r / min. The synchronous motor continues to maintain 3000r / min and switches from the motor mode to the generator mode.

[0020] The speed of the medium and low pressure cylinders is increased to 3005-3010r / min, and engaged with the second SSS clutch. During the engagement process of the medium and low pressure cylinders and the synchronous motor, the speed difference between the medium and low pressure cylinders and the synchronous motor is gradually reduced. After the medium and low pressure cylinders are fully engaged with the synchronous motor, the speed of the medium and low pressure cylinders is restored to 3000r / min.

[0021] Furthermore, when switching from shutdown to power generation, the high-pressure cylinder and the medium- and low-pressure cylinders are started together to reduce the starting time so as to balance the axial thrust.

[0022] Furthermore, when switching from shutdown to power generation, specifically:

[0023] When the high pressure cylinder and the medium and low pressure cylinders are operating at the cranking speed, the first SSS clutch and the second SSS clutch are engaged, and the synchronous motor is connected to the high pressure cylinder and the medium and low pressure cylinders at the same time;

[0024] The speed of the high-pressure cylinder and the medium- and low-pressure cylinders is increased to the warm-up speed for warm-up. After the warm-up is completed, the speed of the high-pressure cylinder and the medium- and low-pressure cylinders is increased at the same time for grid connection.

[0025] Furthermore, when the high-pressure cylinder and the medium- and low-pressure cylinders are simultaneously increased in speed for grid connection, the rate of increase in speed of the high-pressure cylinder is 2.4 times that of the medium- and low-pressure cylinders.

[0026] Furthermore, the warm-up time of the high pressure cylinder and the medium and low pressure cylinders is the same.

[0027] Furthermore, when shutting down, the high pressure cylinder and the medium and low pressure cylinders are shut down together.

[0028] Furthermore, when shutting down, the high pressure cylinder and the medium and low pressure cylinders shut down together, specifically:

[0029] Reduce the loads of the high-pressure cylinder and the medium- and low-pressure cylinders respectively, maintaining the speeds of only 7255 and 3000 r / min, and disconnect the synchronous motor from the grid;

[0030] Make the high-pressure cylinder and the medium- and low-pressure cylinders operate according to the shutdown curve and reduce the speed until they stop.

[0031] Furthermore, it is characterized in that, in the process of reducing the speed until shutdown, the speed reduction rate of the high-pressure cylinder is 2.4 times the speed reduction rate of the medium and low-pressure cylinders.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. By introducing two SSS clutches, the system can flexibly adjust the power transmission path under different working conditions. By controlling the engagement and disengagement of the SSS clutch, the synchronous motor can operate as a generator or a motor, thereby supporting the phase adjustment of the CSP power station or the Carnot battery lava energy storage power station, solving the problem that the existing CSP power station does not have the phase adjustment function; secondly, during the start-up of the synchronous motor, there is no need to use SFC, reducing investment.

[0034] 2. The operating condition switching method provided by the present invention does not require shutdown and bearing replacement, whether switching from generator operating condition to phase adjustment operating condition, from phase adjustment operating condition to power generation operating condition, or from shutdown to power generation operating condition, thereby improving the flexibility of phase adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic diagram of a shaft system of a power generation system with phase adjustment function provided by the present invention;

[0037] In the figure: 1. high-pressure cylinder; 2. gear box; 3. first SSS clutch; 4. synchronous motor; 5. second SSS clutch; 6. medium and low-pressure cylinders. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0042] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] With the rapid development of renewable energy power generation, problems such as low inertia, overvoltage, and broadband oscillation of high-proportion renewable energy are prominent, hindering the expansion of renewable energy power generation. As a basic regulating power source, CSP power station has the dual functions of peak-shaving power source and energy storage, which can provide better long-term peak-shaving capability for the power system. Rotating mechanisms such as synchronous motors and steam turbines also provide rotational inertia for the power grid. However, since the shaft system of the steam turbine and synchronous motor of the CSP power station cannot be separated, the CSP power station does not have the ability of reactive power compensation, which makes the function of the CSP power station unable to be further exerted.

[0045] my country's solar thermal power stations or Carnot battery molten salt energy storage power stations usually use 50MW-class steam turbines as the prime mover for power generation. Since the steam quality generated by the solar thermal power station or Carnot battery molten salt energy storage power station is low, the power generation efficiency of the 50MW-class steam turbine designed according to the existing thermal power generation is low. Therefore, the current solar thermal power station generally adopts a dual-axis, dual-speed design method. Although this shaft system design can significantly improve the relative internal efficiency of the steam turbine, it causes the solar thermal power station to lack the phase adjustment function.

[0046] Publication No. CN117811108A and Publication No. CN109681278A both propose using an SSS clutch to enable the power generation system to have a phase adjustment function. However, on the one hand, their power generation systems are all single-shaft, single-speed designs, which will cause the problem of low power generation efficiency for the application of 50MW units; on the other hand, the existing technology requires shutdown and bearing replacement during the process of switching working conditions, which makes phase adjustment difficult.

[0047] In order to solve the above-mentioned defects of the prior art, the inventor provides a shaft system of a power generation system with phase adjustment function and a working condition switching method.

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0049] like Figure 1 As shown, in the first aspect, an embodiment of the present invention provides a shaft system of a power generation system with a phase adjustment function, the shaft system comprising a high-pressure cylinder 1, a gear box 2, a first SSS clutch 3, a synchronous motor 4, a second SSS clutch 5 and a medium- and low-pressure cylinder 6, the shaft system of the high-pressure cylinder 1 is connected to the shaft system at one end of the gear box 2, and the shaft system at the other end of the gear box 2 is connected to the shaft system of the first SSS clutch 3; the first SSS clutch 3, the synchronous motor 4, the second SSS clutch 5 and the medium- and low-pressure cylinder 6 are coaxially connected in sequence; wherein, the end of the first SSS clutch 3 connected to the high-pressure cylinder 1 is the input end, and the end connected to the synchronous motor 4 is the output end; the end of the second SSS clutch 5 connected to the medium- and low-pressure cylinder 6 is the input end, and the end connected to the synchronous motor 4 is the output end. When the system shaft system is applied to a solar thermal power station or a Carnot battery molten salt energy storage power station, the system shaft system can flexibly adjust the power transmission path under different working conditions of the solar thermal power station or the Carnot battery molten salt energy storage power station through the first SSS clutch 3 and the second SSS clutch 5; at the same time, by controlling the engagement and disengagement of the first clutch SSS3 and the second SSS clutch 5, the synchronous motor 4 can be operated as a generator or a motor, thereby supporting the phase adjustment of the solar thermal power station or the Carnot battery molten salt energy storage power station, and solving the problem that the existing solar thermal power station does not have the phase adjustment function; secondly, during the start-up of the synchronous motor, there is no need to use SFC, which reduces investment. In addition, since the system can adjust the power distribution according to the needs, the load of the high-pressure cylinder 1 and the medium- and low-pressure cylinder 6 is more balanced, reducing unnecessary energy losses. At the same time, the synchronous motor 4 enables the system to more effectively recover and utilize the remaining energy, further improving the overall energy utilization efficiency. Moreover, when the power grid fluctuates or fails, the system shaft system can also respond quickly by adjusting the states of the first SSS clutch 3 and the second SSS clutch 5, changing the power transmission path or adjusting the operating state of the synchronous motor 4, thereby providing necessary support for the power grid and helping to maintain the stability and reliability of the power grid.

[0050] In a second aspect, an embodiment of the present invention provides a method for switching the shaft system operating conditions of a power generation system with a phase adjustment function, including switching from the power generation condition to the phase adjustment condition, switching from the phase adjustment condition to the power generation condition, and switching from shutdown to the power generation condition and the shutdown condition.

[0051] In the process of switching from power generation condition to phase adjustment condition, the load of high pressure cylinder and medium and low pressure cylinder is reduced, and the power control is switched to speed control, so that the speed of high pressure cylinder and medium and low pressure cylinder is maintained at 7255 and 3000r / min respectively; the synchronous motor is switched from generator condition to motor condition through excitation control, and the speed of synchronous motor is maintained at 3000r / min; the speed of high pressure cylinder is reduced to 7200-7250r / min, and the speed of medium and low pressure cylinder is reduced to 2950-2980r / min, so that the first SSS clutch and the second SSS clutch begin to separate, and the synchronous motor is separated from the high pressure cylinder and medium and low pressure cylinder respectively; after the synchronous motor is separated, it is switched to phase adjustment operation, so that the speed of high pressure cylinder and medium and low pressure cylinder is reduced to the cranking speed, with less steam and reactive power and in hot standby state.

[0052] During this adjustment process, the unit can quickly respond to changes in grid demand and flexibly switch from power generation to phase adjustment, thus enhancing the regulation capability and stability of the power system. Under phase adjustment conditions, although the unit does not directly generate electricity, it can support grid voltage stability by adjusting reactive power, reducing energy waste and equipment damage that may be caused by grid voltage fluctuations, and improving the overall energy utilization efficiency. Secondly, in the process of gradually reducing the speed of high-pressure cylinder 1 and medium- and low-pressure cylinder 6, the two SSS clutches are adaptively separated to avoid the impact and damage to the unit equipment caused by sudden speed or load changes, thus extending the service life of the equipment. Finally, the unit under phase adjustment conditions can provide the necessary reactive power support to the grid, which helps to maintain grid voltage fluctuations within a reasonable range, reduce grid failures caused by voltage instability, and improve the stability and reliability of the entire power system. Under phase adjustment conditions, the unit is in a state of low steam reactive power, which reduces unnecessary steam consumption and mechanical wear, and reduces operating costs. At the same time, the hot standby state enables the unit to quickly respond to the need to generate electricity again, reducing startup time and energy consumption. In the event of a sudden grid failure or emergency, the unit in phase adjustment condition can quickly switch to power generation state, providing emergency power support for the grid, thereby enhancing the emergency response and disaster resistance capabilities of the power system.

[0053] When switching from the phase modulation condition to the power generation condition, the synchronous motor is controlled by excitation to maintain the speed of the synchronous motor at 3000r / min; the speed of the high-pressure cylinder is increased to 7260-7300r / min and engaged with the first SSS clutch, and then the high-pressure cylinder is connected to the synchronous motor. During the engagement of the first SSS clutch, the active power absorbed by the synchronous motor from the power grid is gradually reduced to keep the speed of the synchronous motor unchanged; after the high-pressure cylinder is connected to the synchronous motor, the synchronous motor is switched from the motor condition to the generator condition, and the speed of the high-pressure cylinder is restored to 7255r / min. The synchronous motor continues to maintain 3000r / min unchanged and switches from the motor condition to the generator condition; the speed of the medium and low pressure cylinders is increased to 3005-3010r / min and engaged with the second SSS clutch. During the engagement of the medium and low pressure cylinders with the synchronous motor, the speed difference between the medium and low pressure cylinders and the synchronous motor is gradually reduced. After the medium and low pressure cylinders are fully engaged with the synchronous motor, the speed of the medium and low pressure cylinders is restored to 3000r / min. During the whole process, the speed of the synchronous motor 4 is kept stable by excitation control, ensuring the stability of the unit during the switching process. At the same time, the speeds of the high-pressure cylinder 1 and the medium-low pressure cylinder 6 are increased in stages and meshed with the first SSS clutch 3, so that the unit can quickly and stably switch from the phase adjustment condition to the power generation condition, improving the response speed and efficiency of the unit. By accurately controlling the speed recovery process of the high-pressure cylinder 1 and the medium-low pressure cylinder 6, the efficient operation of the unit under the power generation condition is ensured. The synchronous motor 4 smoothly switches from the motor condition to the generator condition, realizing the effective conversion and output of energy. During the whole switching process, by gradually adjusting the speed and load, the mechanical impact and wear of the unit equipment caused by sudden changes are avoided, which helps to extend the service life of the equipment and reduce maintenance costs; after the unit switches from the phase adjustment condition to the power generation condition, it can provide stable power output to the power grid in time, enhancing the stability and reliability of the power system, especially during the peak load period of the power grid or in emergencies, it can quickly respond to and meet the power demand. Under power generation conditions, the unit can fully utilize energy for efficient power generation, reducing energy waste and environmental pollution. Moreover, during the engagement of the first SSS clutch 3, the speed of the synchronous motor 4 is kept unchanged by adjusting the active power absorbed by the synchronous motor 4 from the power grid, which helps to reduce the impact on the power grid caused by sudden changes in speed or load, and maintains the stability and safety of the power grid.

[0054] When switching from shutdown to power generation, the high pressure cylinder and the medium and low pressure cylinders are started together to reduce the start-up time so that the axial thrust is balanced. When the high pressure cylinder and the medium and low pressure cylinders are working at the cranking speed, the first SSS clutch 3 and the second SSS clutch 5 are engaged, and the synchronous motor 4 is connected to the high pressure cylinder 1 and the medium and low pressure cylinder 6 at the same time; the speed of the high pressure cylinder 1 and the medium and low pressure cylinder 6 is increased to the warm-up speed for warming up. After the warm-up is completed, the high pressure cylinder 1 and the medium and low pressure cylinder 6 are increased at the same time for grid connection. When the high pressure cylinder 1 and the medium and low pressure cylinder 6 are increased at the same time for grid connection, the speed increase rate of the high pressure cylinder 1 is 2.4 times the speed increase rate of the medium and low pressure cylinder 6, and the warm-up time of the high pressure cylinder 1 and the medium and low pressure cylinder 6 is consistent. Through the joint start-up of the high pressure cylinder 1 and the medium and low pressure cylinder 6, the overall power of the unit is effectively utilized, the start-up time from shutdown to power generation is significantly shortened, and the response speed of the unit and the reliability of power supply are improved. In the start-up process, the balance of the axial thrust helps to reduce the mechanical stress and wear inside the unit, protect the safety of the equipment, and extend the service life. Secondly, the first SSS clutch 3 and the second SSS clutch 5 are engaged at the cranking speed stage, so that the synchronous motor 4 is connected to the high-pressure cylinder 1 and the medium-low pressure cylinder 6 at the same time, which optimizes the startup process of the unit and reduces the complexity and potential risks in the subsequent steps. In addition, increasing the speed of the high-pressure cylinder 1 and the medium-low pressure cylinder 6 to the warm-up speed for warming up helps the various components of the unit to be heated evenly, reduces thermal stress, and makes full preparations for subsequent grid-connected power generation. At the same time, due to the consistent warm-up time, the thermal state of each part of the unit is coordinated and consistent. During the grid-connected process, the speed increase rate of the high-pressure cylinder 1 and the medium-low pressure cylinder 6 is accurately controlled, especially the increase rate of the high-pressure cylinder 1 is 2.4 times that of the medium-low pressure cylinder 6, which helps to maintain the stable operation of the unit and reduce the vibration and stress that may be caused by speed mismatch. Finally, by simultaneously increasing the speed of the high-pressure cylinder 1 and the medium- and low-pressure cylinders 6 for grid connection, the unit can be continuously and efficiently converted from startup to power generation, the grid connection efficiency can be improved, grid fluctuations and energy waste can be reduced, and the efficient and smooth progress of the entire startup and grid connection process can help enhance the overall stability of the power system, improve the power supply quality, and reduce grid failures that may be caused by unstable factors during the unit startup and grid connection process.

[0055] When shutting down, the high pressure cylinder and the medium and low pressure cylinders are shut down together, and the loads of the high pressure cylinder and the medium and low pressure cylinders are reduced to only 7255 and 3000r / min, and the synchronous motor is disconnected from the grid; the high pressure cylinder and the medium and low pressure cylinders are operated according to the shutdown curve, and the speed is reduced until the shutdown. In the process of reducing the speed until the shutdown, the speed reduction rate of the high pressure cylinder is 2.4 times the speed reduction rate of the medium and low pressure cylinder. By reducing the load of the high pressure cylinder 1 and the medium and low pressure cylinder 6 to, and maintaining the speed of 7255 and 3000r / min, and disconnecting the synchronous motor 4 in the process, the smooth transition of the unit from the power generation state to the shutdown state is ensured. The orderly load reduction and off-grid operation help reduce the stress and impact inside the unit and protect the safety of the equipment. In the process of reducing the speed until the shutdown, the speed reduction rate of the high-pressure cylinder 1 is 2.4 times that of the medium- and low-pressure cylinders 6. By accurately controlling the speed reduction rate, it is possible to ensure that the unit maintains a stable operating state during the shutdown process and reduce the vibration and stress that may be caused by too fast speed changes. In the process of shutdown, the use of a joint shutdown method and an optimized speed reduction strategy can help shorten the shutdown time of the unit. By simultaneously reducing the speeds of the high-pressure cylinder 1 and the medium- and low-pressure cylinders 6 and reasonably controlling the speed reduction rate, it can ensure that the unit completes the shutdown process in a shorter time and improves the overall operating efficiency of the unit. In addition, during the shutdown process, the shutdown curve is followed to ensure that each component of the unit is gradually reduced to the shutdown state according to the predetermined speed and temperature curve. This orderly shutdown process helps to reduce the thermal stress and mechanical stress inside the equipment, protect the equipment from damage, and extend its service life. Through precise load reduction, synchronous motor off-grid, and optimized speed reduction strategy, the entire shutdown process is safer and more controllable, which helps to reduce safety accidents that may be caused by improper operation or equipment failure, and ensure the safety of the unit and personnel. Finally, the orderly shutdown process facilitates subsequent unit maintenance and overhaul work. When the unit is completely shut down and in a stable state, maintenance personnel can perform equipment inspection, repair and replacement more safely and efficiently to ensure that the unit can maintain a good operating condition when it is started next time.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A shaft system of a power generation system with phase adjustment function, characterized in that: include: A high-pressure cylinder (1), a synchronous motor (4), a second SSS clutch (5) and a medium- and low-pressure cylinder (6), wherein the shaft system of the high-pressure cylinder (1) is connected to the shaft system at one end of the gear box (2), and the shaft system at the other end of the gear box (2) is connected to the shaft system of the first SSS clutch (3); The first SSS clutch (3), the synchronous motor (4), the second SSS clutch (5) and the medium and low pressure cylinders (6) are coaxially connected in sequence; Wherein, the end of the first SSS clutch (3) connected to the high-pressure cylinder (1) is the input end, and the end connected to the synchronous motor (4) is the output end; The end of the second SSS clutch (5) connected to the medium and low pressure cylinder (6) is an input end, and the end connected to the synchronous motor (4) is an output end.

2. A method for switching shaft operating conditions of a power generation system with phase adjustment function, characterized in that: When switching from power generation to phase adjustment, it includes: The loads of the high-pressure cylinder and the medium- and low-pressure cylinders are reduced, and the power control is switched to the speed control, so that the speeds of the high-pressure cylinder and the medium- and low-pressure cylinders are maintained at 7255 and 3000 r / min, respectively; The synchronous motor is switched from a generator mode to a motor mode through excitation control, and the synchronous motor is kept at a speed of 3000 r / min; The speed of the high-pressure cylinder is reduced to 7200-7250r / min, and the speed of the medium- and low-pressure cylinders is reduced to 2950-2980r / min, so that the first SSS clutch and the second SSS clutch begin to separate, and the synchronous motor is separated from the high-pressure cylinder and the medium- and low-pressure cylinders respectively; After separating the synchronous motor, switch to phase-adjusting operation, so that the speed of high-pressure cylinder and medium- and low-pressure cylinders is reduced to the cranking speed, with less steam and reactive power, and in hot standby state.

3. The operating mode switching method according to claim 2, characterized in that: When switching from phase adjustment to power generation, it includes: The synchronous motor is controlled through excitation to maintain the speed of the synchronous motor at 3000r / min; The speed of the high-pressure cylinder is increased to 7260-7300 r / min and engaged with the first SSS clutch, and then the high-pressure cylinder is connected to the synchronous motor. During the engagement of the first SSS clutch, the active power absorbed by the synchronous motor from the power grid is gradually reduced to keep the speed of the synchronous motor unchanged. After connecting the high-pressure cylinder to the synchronous motor, switch the synchronous motor from the motor mode to the generator mode, and restore the speed of the high-pressure cylinder to 7255r / min, while the synchronous motor maintains 3000r / min; The speed of the medium and low pressure cylinders is increased to 3005-3010 / min, and engaged with the second SSS clutch. During the engagement process of the medium and low pressure cylinders and the synchronous motor, the speed difference between the medium and low pressure cylinders and the synchronous motor is gradually reduced. After the medium and low pressure cylinders are fully engaged with the synchronous motor, the speed of the medium and low pressure cylinders is restored to 3000r / min.

4. The operating mode switching method according to claim 2, characterized in that: When switching from shutdown to power generation, the high-pressure cylinder and the medium- and low-pressure cylinders are started together to reduce the starting time and balance the axial thrust.

5. The operating mode switching method according to claim 4, characterized in that: When switching from shutdown to power generation, specifically: When the high pressure cylinder and the medium and low pressure cylinders are operating at the cranking speed, the first SSS clutch and the second SSS clutch are engaged, and the synchronous motor is connected to the high pressure cylinder and the medium and low pressure cylinders at the same time; The speed of the high-pressure cylinder and the medium- and low-pressure cylinders is increased to the warm-up speed for warm-up. After the warm-up is completed, the speed of the high-pressure cylinder and the medium- and low-pressure cylinders is increased at the same time for grid connection.

6. The operating mode switching method according to claim 5, characterized in that: When the high-pressure cylinder and the medium- and low-pressure cylinders are increased in speed at the same time for grid connection, the rate of increase of the high-pressure cylinder's speed is 2.4 times that of the medium- and low-pressure cylinders' speed.

7. The operating mode switching method according to claim 5, characterized in that: The warm-up time of the high-pressure cylinder and the medium- and low-pressure cylinders is the same.

8. The operating mode switching method according to claim 2, characterized in that: When shutting down, the high pressure cylinder and the medium and low pressure cylinders shut down together.

9. The operating mode switching method according to claim 8, characterized in that: When shutting down, the high pressure cylinder and the medium and low pressure cylinders shut down together, specifically: Reduce the loads of the high-pressure cylinder and the medium- and low-pressure cylinders respectively, maintaining the speeds of only 7255 and 3000 r / min, and disconnect the synchronous motor from the grid; Make the high-pressure cylinder and the medium- and low-pressure cylinders operate according to the shutdown curve and reduce the speed until they stop.

10. The operating mode switching method according to claim 9, characterized in that: In the process of reducing the speed until stopping, the speed reduction rate of the high-pressure cylinder is 2.4 times that of the medium and low-pressure cylinders.

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