Double-speed four-pole multiphase steam turbine generator with extraction-type staggered ventilation cooling system

Abstract

The present invention discloses a double-speed four-pole multi-phase steam turbogenerator with an exhaust-type staggered ventilation cooling system, which relates to the field of electric motors. To address the low operating capacity and high temperature problems of existing steam turbogenerators, the present invention operates at twice the synchronous speed of 3000 rpm. The stator multi-phase windings induce 100 Hz multi-phase AC power, which is converted to 50 Hz three-phase AC power by a converter and then connected to the power grid. The straight section of the stator core is divided into n cold air zones and n+1 hot air zones. Internal cooling ventilation ducts are provided in the stator core teeth. Exhaust fans are installed on both sides of the generator, and push-in fans are installed outside the guard rings at both ends. The rotor's secondary slots are connected to the rotor's radial ventilation holes. Permanent magnets are installed below the rotor windings, contacting the permanent magnets with the secondary slots. The rotor's secondary slots and the permanent magnet secondary slots are connected at the generator's axial center through radial ventilation holes. The present invention improves the generator's operating capacity and cooling efficiency, and has a simple structure and is easy to implement.

Description

Technical Field

[0001] The invention relates to a double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system, belonging to the field of motors. Background Art

[0002] In recent years, with the growth of renewable energy in transmission and distribution, there has been a growing awareness of the urgent need for traditional power plants to operate flexibly to ensure power system stability. Steam turbine generators in traditional power plants are directly connected to the grid and cannot operate at speeds independent of the grid frequency, making them unable to effectively withstand abnormal and severe voltage and frequency fluctuations. Traditional half-speed steam turbine generators generate their magnetic field solely by passing a DC excitation current through the rotor excitation windings. This low rotor speed results in low power density. Large-capacity steam turbine generators have high unit capacity, and each phase of a three-phase generator carries a significant power load. A single phase failure in the generator can render the generator inoperable. Furthermore, the axial length of the turbine generator rotor is long, and an inadequately designed ventilation and cooling system prevents heat generated within the generator from being promptly removed by the cooling air. If the allowable temperature rise exceeds this limit, the safe, stable operation and lifespan of the turbine generator are seriously threatened.

[0003] To enable flexible grid-connected operation at speeds independent of grid frequency, expand the grid voltage and frequency regulation range, increase the power density of the turbine generator, reduce the power load on each phase of the stator winding, and lower the temperature of large-capacity turbine generator components, a double-speed four-pole multiphase turbine generator with an extractive interleaved ventilation cooling system can be used. The speed of the four-pole turbine generator is doubled from 1500 rpm to 3000 rpm, connected to the grid via a multiphase converter and a three-phase step-up transformer. Hybrid excitation using electric excitation and permanent magnet excitation effectively increases the turbine generator's power density. The stator uses multiphase windings, and the power load on each phase decreases as the number of phases increases. Furthermore, if a phase winding fails, the remaining windings can continue to operate using fault-tolerant control, improving the reliability and redundancy of the entire system. The staggered ventilation cooling system in the double-speed four-pole multi-phase steam turbine generator can increase the flow rate of cooling gas in the generator, accelerate the fluid flow rate in the four-pole multi-phase steam turbine generator, effectively reduce the maximum temperature of each component in the generator, reduce the temperature difference and thermal stress in the axial direction of the generator, and improve the long-term safe and stable operation capability of the steam turbine generator. Summary of the Invention

[0004] The purpose of the present invention is to provide a double-speed four-pole multi-phase steam turbine generator with an exhaust-type staggered ventilation cooling system to solve the problem that traditional steam turbine generators operate at a speed independent of the grid frequency and the high temperature of components caused by the increase in speed, so that the steam turbine generator can operate at a speed independent of the grid frequency. It can also solve the problem of excessive temperature of components inside the generator, speed up the flow rate of cooling gas in the generator, effectively reduce the temperature of various components in the generator, and enhance the ability of the steam turbine generator to operate safely and stably.

[0005] The invention provides a double-speed four-pole multi-phase steam turbine generator with an exhaust-type staggered ventilation cooling system, comprising a cold air zone inlet, a cooler, a hot air zone outlet, a casing, a pressure finger, an exhaust-type fan, a pressure-in type fan, a stator core, a rotor core, a rotor auxiliary slot, a rotor excitation winding, a permanent magnet auxiliary slot, a permanent magnet, a rotor winding radial ventilation hole, a stator winding, a stator core tooth ventilation duct, a rotor guard ring, radial ventilation holes, a high-coercivity permanent magnet, and a low-coercivity permanent magnet. The four-pole multi-phase steam turbine generator operates at twice the synchronous speed of 3000 rpm, and the stator multi-phase winding The 100Hz multi-phase AC power induced by the group is converted into 50Hz three-phase AC power through a converter and then connected to the power grid. The straight section of the stator core is divided into n cold air zones and n+1 hot air zones. The stator core teeth are provided with internal cooling ventilation ducts. The exhaust fans are installed on both sides of the generator, and the push-in fans are installed on the outside of the guard rings at both ends. The rotor auxiliary slots are connected to the rotor radial ventilation holes. Permanent magnets are installed under the rotor windings and are in contact with the permanent magnet auxiliary slots. The rotor auxiliary slots and the permanent magnet auxiliary slots are connected through radial ventilation holes at the axial center of the generator.

[0006] The number of n cold air zones is 3-6; the width of the radial ventilation groove of the stator core is 3mm to 8mm; the cross-section of the rotor auxiliary slot ventilation duct is rectangular, and the length of the rotor auxiliary slot ventilation duct cross-section is 20mm to 30mm; the width of the rotor auxiliary slot ventilation duct cross-section is 10-20mm; the width of the stator core tooth ventilation duct is 5-15mm; the length of the stator core tooth ventilation duct is 2mm to 5mm.

[0007] Preferably, the permanent magnet is adjusted from one permanent magnet to consist of a high coercive force permanent magnet and a low coercive force permanent magnet. The high coercive force permanent magnet and the low coercive force permanent magnet can generate a more reasonable magnetic field and improve the waveform of the sinusoidal magnetic field in the air gap.

[0008] Preferably, the cross-section of the stator core tooth ventilation duct at the stator core tooth top is changed from rectangular to circular, which further accelerates the flow rate of the cooling gas around the stator core tooth top, improves the ability of the cooling gas to carry away the heat of the stator core, and further reduces the maximum temperature of the stator core.

[0009] Preferably, the stator core tooth ventilation duct is adjusted to a tooth ventilation duct with a rectangular cross-section, which effectively reduces the manufacturing cost and can also ensure the cooling effect of the stator core teeth.

[0010] Advantages of the present invention: The half-speed four-pole steam turbine generator of a traditional power plant is directly connected to the power grid and cannot operate at a speed independent of the grid frequency. It cannot effectively resist abnormal and serious voltage and frequency fluctuation events, has a low power density, and the temperature of the internal components of the half-speed four-pole steam turbine generator is high. The present invention increases the speed of the half-speed four-pole steam turbine generator from 1500r / min to 3000r / min through a steam turbine, that is, the speed is doubled, and the stator multi-phase winding induces 100Hz multi-phase alternating current, which is converted into 50Hz three-phase alternating current through a multi-phase converter and a three-phase step-up transformer and connected to the power grid. The double-speed four-pole steam turbine generator thus constructed can operate at a speed independent of the grid frequency, effectively reducing the size of the steam turbine generator and reducing the processing and manufacturing costs; the power density of the steam turbine generator is increased by hybrid excitation of permanent magnets and electric excitation; the stator adopts multi-phase windings, and as the number of phases increases, each phase increases. The magnetic flux and back electromotive force of the phase winding will decrease proportionally, and the supply voltage will drop accordingly, thereby achieving low-voltage and high-power output. When a phase winding of the stator fails, the other windings can match the fault-tolerant control strategy and continue to work, thereby improving the reliability and redundancy of the entire system. In terms of ventilation and cooling, a new push-in fan is added to the outer side of the guard ring of the double-speed four-pole steam turbine generator. The original blower fans on both sides of the generator are changed to exhaust fans, and the original single ventilation system of the generator is changed to an interlaced ventilation system, which speeds up the flow rate of the cooling gas, effectively reduces the temperature of each component, and reduces the temperature difference and thermal stress in the axial direction of the generator. The power density, ventilation and cooling effect, and improvement effect on the power grid of the double-speed four-pole multi-phase steam turbine generator with an exhaust-type interlaced ventilation cooling system described in the present invention are significantly better than those of traditional steam turbine generators, and have fault tolerance. Compared with traditional steam turbine generators, it has higher reliability and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For ease of explanation, the present invention is described in detail with reference to the following specific implementations and accompanying drawings.

[0012] Figure 1 This is a cross-sectional view of the double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system according to the present invention.

[0013] Figure 2 This is a radial cross-sectional view of the rotor region of the double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system according to the present invention.

[0014] Figure 3This is a partial enlarged view of the radial cross-section of the stator region and rotor region of the double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system according to the present invention.

[0015] Figure 4 This is a cross-sectional view at position NN of the double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system according to the present invention.

[0016] Figure 5 This is a partial enlarged view of the radial cross-section of the stator region and rotor region of the double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system as described in the second specific embodiment of the present invention.

[0017] Figure 6 This is a partial enlarged view of the radial cross-section of the stator region and rotor region of the double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system described in the third specific embodiment of the present invention.

[0018] Figure 7 This is a partial enlarged view of the radial cross-section of the stator region and rotor region of the double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system as described in the fourth specific embodiment of the present invention.

[0019] In the figure: 1 - cold air zone inlet, 2 - cooler, 3 - hot air zone outlet, 4 - housing, 5 - pressure finger, 6 - extraction fan, 7 - injection fan, 8 - stator core, 9 - rotor core, 10 - rotor auxiliary slots, 11 - rotor excitation winding, 12 - permanent magnet auxiliary slots, 13 - permanent magnets, 14 - rotor winding radial ventilation holes, 15 - stator winding, 16 - stator core tooth ventilation duct, 17 - rotor guard ring, 18 - radial ventilation holes, 19 - high-coercivity permanent magnets, 20 - low-coercivity permanent magnets. The arrows in the figure indicate the flow direction of cooling gas within a double-speed, four-pole, multi-phase steam turbogenerator with an extraction-type staggered ventilation cooling system. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0021] Specific implementation method 1: Combination Figure 1 、 Figure 2 、 Figure 3 、 Figure 4This embodiment includes a cold air zone inlet 1, a cooler 2, a hot air zone outlet 3, a housing 4, a pressure finger 5, an exhaust fan 6, a pressure fan 7, a stator core 8, a rotor core 9, a rotor auxiliary slot 10, a rotor excitation winding 11, a permanent magnet auxiliary slot 12, a permanent magnet 13, a rotor winding radial ventilation hole 14, a stator winding 15, a stator core tooth ventilation duct 16, a rotor guard ring 17, a radial ventilation hole 18, a high coercive force permanent magnet 19 and a low coercive force permanent magnet 20. The four-pole multiphase steam turbine generator operates at 2 times the synchronous speed of 3000 rpm, and the stator multiphase winding induces 10 0Hz multi-phase AC power is converted to 50Hz three-phase AC power through a converter and then connected to the power grid. The straight section of the stator core is divided into n cold air zones and n+1 hot air zones. Internal cooling ventilation ducts 16 are opened on the teeth of the stator core. Extraction fans 6 are installed on both sides of the generator, and push-in fans 7 are installed on the outside of the protective rings at both ends. The rotor auxiliary slots 10 are connected to the rotor radial ventilation holes 14. Permanent magnets 13 are installed under the rotor windings and are in contact with the permanent magnet auxiliary slots 12. The rotor auxiliary slots 10 and the permanent magnet auxiliary slots 12 are connected at the axial center of the generator through radial ventilation holes 18.

[0022] The number of n cold air zones is 3-6, and is 3 in this embodiment; the width of the radial ventilation groove of the stator core is 3mm to 8mm, and is 6mm in this embodiment; the cross-section of the ventilation duct of the rotor auxiliary slot 10 is rectangular, and the length of the ventilation duct cross-section of the rotor auxiliary slot 10 is 20mm to 30mm, and is 25mm in this embodiment; the width of the ventilation duct cross-section of the rotor auxiliary slot 10 is 10-20mm, and is 15mm in this embodiment; the width of the stator core tooth ventilation duct 18 is 5-15mm, and is 7mm in this embodiment; the length of the stator core tooth ventilation duct 18 is 2mm to 5mm, and is 3mm in this embodiment.

[0023] The speed of a traditional four-pole, three-phase steam turbine generator is doubled, increasing the synchronous speed from 1500 rpm to 3000 rpm. The original three-phase stator winding is replaced with a multi-phase stator winding. A rectangular slot is created in the rotor core 9 below the original rotor excitation winding, with permanent magnets 13 inserted from both sides. The blower fans on both sides of the generator are replaced with exhaust fans 6, and a push-in fan 7 is added to the outer side of the four-pole steam turbine generator's retaining ring, transforming the generator's single ventilation system into an interleaved cooling ventilation system. When the steam turbine drives the double-speed four-pole, multi-phase steam turbine generator, 100 Hz multi-phase AC power is induced in the stator winding. This power is then connected to the power grid via a multi-phase converter and a three-phase step-up transformer, thereby expanding the grid's voltage and frequency range, protecting against abnormal and severe voltage and frequency fluctuations, and increasing the turbine generator's leading-phase operation depth, providing the grid with the required large amounts of reactive power. As the number of stator winding phases increases, the magnetic flux or back electromotive force of each phase winding decreases proportionally, and the voltage of each phase decreases accordingly, which can achieve low-voltage and high-power output. If one phase of the stator winding fails, the other windings can match the fault-tolerant control strategy and continue to work, thereby improving the reliability and redundancy of the entire system. In terms of the performance of the four-pole multi-phase steam turbine generator, the permanent magnet 13 below the rotor excitation winding 11 can effectively improve the waveform of the sinusoidal magnetic field in the air gap of the four-pole multi-phase steam turbine generator, enhance the magnetic field strength in the air gap, and effectively reduce the magnitude of the rotor excitation current. By changing the magnitude of the current in the rotor excitation winding 11, the magnetic field strength in the air gap can be effectively adjusted, thereby changing the working state of the four-pole multi-phase steam turbine generator, effectively improving the power density of the four-pole multi-phase steam turbine generator, and reducing the volume of the four-pole multi-phase steam turbine generator.In terms of the ventilation and cooling system of the four-pole multi-phase steam turbine generator, the cooling gas is cooled by the cooler 2 and then directly enters the interior of the four-pole multi-phase steam turbine generator. One path of cooling gas enters the straight section area of ​​the four-pole multi-phase steam turbine generator from the cold air zone inlet 1, and enters the stator radial ventilation groove from the back of the stator core. A part of the cooling gas in this path enters the stator core tooth internal cooling ventilation duct 16, which increases the contact area between the cooling gas and the stator core teeth, increases the heat dissipation coefficient of the stator core teeth, and effectively reduces the temperature of the stator core teeth. Another part of the cooling gas enters the air gap between the stator core and the rotor core, reducing the temperature of the stator core tooth top and the rotor core. These two parts of cooling gas enter the adjacent hot air zone through the stator core tooth internal cooling ventilation duct and the air gap between the stator core 8 and the rotor core 8, cooling the heat. After passing through the stator core 8 in the wind zone, it flows out from the outlet 3 of the hot wind zone and enters the base cavity at the back of the stator core; another path of cooling gas enters the end area of ​​the four-pole multi-phase steam turbine generator, and under the action of the forced-in fan 7, a part of the cooling gas enters the rotor sub-slot 10 and the permanent magnet sub-slot 12, which can effectively take away the heat of the rotor winding 11 and the permanent magnet 13, and significantly reduce the temperature of the rotor winding 11 and the permanent magnet 13. This part of the cooling gas reaches the middle position of the four-pole multi-phase steam turbine generator along the axial direction and then merges into the air gap between the stator core 8 and the rotor core 9 through the radial ventilation groove 18, which can further reduce the temperature of the rotor winding. Another part of the cooling gas directly enters the air gap between the stator core 8 and the rotor core 9. These two parts of cooling gas finally pass through the stator radial ventilation groove and enter the base cavity at the back of the stator core 8. The two streams of gas that converge in the cavity of the machine base at the back of the stator core are extracted by the exhaust fan 6. This solves the problem of the cooling gas being heated by the fan when the traditional blast fan presses the cooling gas into the steam turbine generator. The cooling gas extracted by the exhaust fan 6 is then cooled by the cooler 2 and directly enters the interior of the four-pole multi-phase steam turbine generator, thus completing the entire cooling cycle. The double-speed four-pole multi-phase steam turbine generator with an exhaust-type staggered ventilation cooling system can effectively enhance the magnetic field strength within the generator, reduce the magnitude of the rotor excitation current, increase the flow rate of the cooling gas, accelerate the flow rate of the fluid within the double-speed four-pole multi-phase steam turbine generator, effectively reduce the temperature of the various components within the generator, and improve the cooling effect within the generator. In addition, since the rotor speed is doubled, the volume of the four-pole steam turbine generator is significantly reduced, saving materials, reducing the manufacturing cost of the four-pole steam turbine generator, and enhancing the ability of the four-pole steam turbine generator to operate safely and reliably for a long time.

[0024] Specific implementation method 2: Combination Figure 5This embodiment differs from the first embodiment in that permanent magnet 13 is modified from a single permanent magnet to include a high-coercivity permanent magnet 19 and a low-coercivity permanent magnet 20. This combination of high-coercivity permanent magnet 19 and low-coercivity permanent magnet 20 generates a more optimal magnetic field, improving the waveform of the sinusoidal magnetic field within the air gap. The remaining components and connections are the same as those in the first embodiment.

[0025] Specific implementation method three: Combination Figure 6 This embodiment differs from the first embodiment in that the cross-section of the stator core tooth ventilation duct 16 at the tooth tips of the stator core 8 is changed from a rectangular to a circular shape. This further increases the flow rate of the cooling gas around the tooth tips of the stator core 8, improving the cooling gas's ability to remove heat from the stator core 8 and further reducing the maximum temperature of the stator core 8. The remaining components and connections are the same as those of the first embodiment.

[0026] Specific implementation method four: Combination Figure 7 This embodiment differs from the first embodiment in that the stator core tooth ventilation duct 16 is modified to have a rectangular cross-section, effectively reducing manufacturing costs while ensuring effective cooling of the stator core 8 teeth. The remaining components and connections are the same as those in the first embodiment.

[0027] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A double-speed four-pole multiphase steam turbine generator with an extraction-type staggered ventilation cooling system, characterized by: It includes a cold air zone inlet (1), a cooler (2), a hot air zone outlet (3), a casing (4), a pressure finger (5), an exhaust fan (6), a pressure fan (7), a stator core (8), a rotor core (9), a rotor auxiliary slot (10), a rotor excitation winding (11), a permanent magnet auxiliary slot (12), a permanent magnet (13), a rotor winding radial ventilation hole (14), a stator winding (15), a stator core tooth ventilation duct (16), a rotor guard ring (17), a radial ventilation hole (18), a high coercive force permanent magnet (19) and a low coercive force permanent magnet (20). The four-pole multiphase steam turbine generator operates at twice the synchronous speed of 3000 rpm. The stator multiphase winding The induced 100Hz multi-phase alternating current is converted into 50Hz three-phase alternating current through a converter and then connected to a power grid. The straight section of the stator core is divided into n cold air zones and n+1 hot air zones. An internal cooling ventilation duct (16) is provided on the teeth of the stator core. An exhaust fan (6) is installed on both sides of the generator. A push-in fan (7) is installed on the outside of the guard rings at both ends. The rotor auxiliary slot (10) is connected to the rotor radial ventilation hole (14). A permanent magnet (13) is installed below the rotor winding. The permanent magnet (13) is in contact with the permanent magnet auxiliary slot (12). The rotor auxiliary slot (10) and the permanent magnet auxiliary slot (12) are connected at the axial center position of the generator through a radial ventilation hole (18).

2. The double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system according to claim 1, characterized in that: The number of n cold air zones is 3-6; the width of the radial ventilation groove of the stator core is 3mm to 8mm; the cross section of the ventilation duct of the rotor auxiliary slot (10) is rectangular, and the length of the ventilation duct cross section of the rotor auxiliary slot (10) is 20mm to 30mm; the width of the ventilation duct cross section of the rotor auxiliary slot (10) is 10-20mm; the width of the ventilation duct (18) of the teeth of the stator core is 5-15mm; and the length of the ventilation duct (18) of the teeth of the stator core is 2mm to 5mm.

3. The double-speed four-pole multi-phase steam turbine generator with an exhaust-type staggered ventilation cooling system according to claim 1, characterized in that: The permanent magnet (13) consists of a high-coercive force permanent magnet (19) and a low-coercive force permanent magnet (20).

4. The double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system according to claim 1, characterized in that: The cross section of the stator core tooth ventilation duct (16) at the tooth top of the stator core (8) is circular.

5. The double-speed four-pole multi-phase steam turbine generator with an extraction-type staggered ventilation cooling system according to claim 1, characterized in that: The stator core tooth ventilation duct (16) is a tooth ventilation duct with a rectangular cross section.

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