A steam turbine overspeed prevention system

Abstract

The utility model provides a steam turbine overspeed prevention system, including a steam turbine and a generator connected to the steam turbine. It also includes a flywheel device, which includes a flywheel and a flywheel motor, wherein the flywheel rotor is connected to the flywheel motor, the generator output line is connected to the flywheel through a flywheel device switch, and the flywheel can be rotated by powering the generator. It also includes a switch, a bidirectional converter and a first to-grid switch, wherein the flywheel motor is connected to the bidirectional converter through the switch, and the bidirectional converter is connected to the grid through the first to-grid switch. The flywheel energy storage method is used to convert the residual energy of steam into the kinetic energy of the flywheel, and the speed control of the steam turbine is achieved through the regulation of the flywheel generator, and the electric energy can be recovered to avoid waste, thereby increasing the economic benefits for the enterprise.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbine control in power plants, in particular to a steam turbine overspeed prevention system. Background Art

[0002] Steam turbine overspeed accidents are vicious accidents in power plants, which are extremely harmful. Steam turbine overspeed will cause blades, bolts and other parts to fly out, causing serious damage to equipment and personal injury. Generator overspeed will cause damage to sealing tiles and a large amount of hydrogen leakage from the generator end cover, which will cause hydrogen explosion accidents, causing serious damage to equipment and large-scale fire accidents on site. Although a variety of inspection and maintenance and operation adjustment methods are adopted, steam turbine overspeed accidents often occur, causing great economic losses and personal injuries.

[0003] In the spot market mode, due to the frequent start and stop of thermal power units, the oxide scale inside the equipment falls off, and the oxide scale of the steam turbine inlet valve is blocked, resulting in jamming, which usually requires the unit to be shut down or tripped. Although the unit can be disconnected from the power grid in time, the steam inlet of the steam turbine cannot be cut off at the same time, resulting in an overspeed accident of the steam turbine under the impulse of steam. In view of the above shortcomings, an improved steam turbine bypass system is provided. Summary of the invention

[0004] The technical solution adopted by the utility model to solve its technical problems is:

[0005] Provided is a steam turbine overspeed prevention system, comprising a steam turbine and a generator transmission-connected to the steam turbine, and also comprising an excitation device, wherein the excitation device can apply the excitation required for power generation to the generator, and the generator output line is connected to the power grid through a second to-grid switch; and also comprising a flywheel device, which comprises a flywheel and a flywheel motor, wherein the flywheel comprises a flywheel rotor and a stator, the flywheel rotor is transmission-connected to the flywheel motor, the generator output line is connected to the flywheel through a flywheel device switch, and the flywheel can be rotated by supplying power through the generator, and also comprising a switch, a bidirectional converter and a first to-grid switch, wherein the flywheel motor is connected to the bidirectional converter through the switch, and the bidirectional converter is connected to the power grid through the first to-grid switch.

[0006] Preferably, it further comprises a battery and a battery switch, and the bidirectional converter is connected to the battery via the battery switch.

[0007] Preferably, the battery is connected to the flywheel and can drive the flywheel to rotate.

[0008] The beneficial effect of the utility model is that the surplus energy of steam is converted into the kinetic energy of the flywheel by utilizing the flywheel energy storage method, and the speed of the steam turbine is controlled by adjusting the flywheel generator, and the electric energy can be recovered to avoid waste, thereby increasing the economic benefits for the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 It is a schematic diagram of the structure of the steam turbine overspeed prevention system provided by the embodiment of the utility model;

[0011] In the figure: 1-steam turbine, 2-generator, 3-excitation device, 4-grid, 5-flywheel device, 6-battery, 7-bidirectional converter, 8-excitation power supply, 9-steam turbine steam inlet valve, 10-excitation switch, 11-battery switch, 12-flywheel device switch, 13-switch, 14-first switch to grid, 15-second switch to grid, 16-steam turbine generator rotor. DETAILED DESCRIPTION

[0012] The above scheme is further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the utility model rather than to limit the scope of the utility model. The implementation conditions used in the examples can be further adjusted according to the conditions of the specific manufacturer, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0013] In a specific embodiment, a steam turbine overspeed prevention system is provided, comprising an existing steam turbine 1 and a generator 2 transmission-connected to the steam turbine 1, and also comprising an existing excitation device 3, the excitation device 3 being capable of applying the excitation required for power generation to the rotor or stator of the generator 2, the output line of the generator 2 being connected to the power grid 4 via a second to power grid switch 15, therefore, when the steam turbine 1 drives the generator 2 to rotate, power will be generated and input into the power grid 4.

[0014] In this example, in order to avoid the phenomenon of turbine overspeed due to the impulse of steam, a flywheel device 5 is also included, which specifically includes a flywheel and a flywheel motor. The flywheel in this example includes a flywheel rotor and a stator. The flywheel rotor is connected to the flywheel motor in a transmission manner so that the two can rotate simultaneously.

[0015] In addition, the output line of the generator 2 is connected to the flywheel through the flywheel device switch 12. The flywheel can rotate by powering the generator 2. At this time, the flywheel drives the flywheel motor to rotate and generate electricity. On this basis, it also includes a switch 13, a bidirectional converter 7 and a first to-grid switch 14. The flywheel motor is connected to the bidirectional converter 7 through the switch 13, and the bidirectional converter 7 is connected to the grid 4 through the first to-grid switch 14.

[0016] The specific working process is that after shutdown, first disconnect the second switch 15 to the power grid. At this time, the steam inlet valve 9 of the steam turbine will not be closed tightly. Under the impulse of steam, the overspeed of the steam turbine 1 will quickly rise from 3000r / min to 3200r / min. At this time, close the excitation switch 10, and excite the generator 2 through the excitation device 3, so that the generator 2 generates voltage and generates electricity.

[0017] Then, the flywheel device switch 12 is closed, and the flywheel rotor of the flywheel device 5 starts to increase speed. At this time, the flywheel drives the flywheel motor to rotate (at this time, the flywheel motor is in the power generation state). According to the speed of the steam turbine, the higher the speed of the steam turbine, the further the excitation current is increased. The larger the excitation current, the faster the flywheel speed increases; the faster the steam turbine speed increases, the faster the excitation current increases, and the greater the flywheel speed increase rate. Due to the increase in excitation current, the greater the electromagnetic torque of the steam turbine, the turbine speed increase is suppressed. Therefore, the speed increase rate of the flywheel can be adjusted by the flywheel motor according to the speed of the steam turbine 2 and the speed increase rate, and the steam turbine speed can be controlled below 3300r / min. Then, the switch 13 and the first to the power grid switch 14 are closed, and the output frequency of the flywheel motor is matched with the frequency of the power grid 4 through the bidirectional converter 7, and the electric energy generated by the flywheel motor is input into the power grid 4. Then, regeneration is achieved while achieving speed control.

[0018] Finally, after the flywheel energy is released, the first to grid switch 14 and the switch 13 are opened, and the flywheel device is shut down for standby.

[0019] Therefore, the flywheel energy storage method is used to convert the surplus energy of steam into the kinetic energy of the flywheel, and the speed of the steam turbine 2 is controlled by adjusting the flywheel generator. In addition, the electrical energy can be recovered to avoid waste, thereby increasing the economic benefits for the enterprise.

[0020] On this basis, it also includes a battery 6 and a battery switch 11, and the bidirectional converter 7 is connected to the battery 6 through the battery switch 11. The main purpose is to recycle the electric energy generated by the flywheel motor to the battery 6. Different from the operation of recycling to the power grid, the first switch 14 to the power grid remains disconnected, and the switch 13 and the battery switch 11 are closed, at this time, a circuit for charging the battery 6 is formed, thereby realizing energy storage, avoiding waste, and increasing economic benefits for the enterprise.

[0021] The turbine speed is controlled within the rated range by adjusting the speed of the flywheel and a flywheel generator is provided at the end of the flywheel shaft to store and output energy. At the same time, the energy of the boiler waste steam can also be effectively utilized, which improves the reliability of the equipment and increases the economic benefits for the enterprise.

[0022] In addition, it should be noted that the flywheel motor can be powered by the battery 6 to drive the flywheel motor to rotate (the flywheel motor is an electric motor at this time) to drive the flywheel to rotate. When the flywheel rotates, the flywheel motor is switched to a power generation state again and the power grid is powered. Due to the inertia of the flywheel, the electric energy of the battery 6 can be transmitted to the power grid to a certain extent, thereby improving the economic effect.

[0023] In addition, the storage battery 6 can also be connected to the flywheel to drive the flywheel to rotate and generate electricity.

[0024] Based on the above ideal embodiments of the utility model, the relevant staff can make various changes and modifications without departing from the technical concept of the invention through the above description. The technical scope of the invention is not limited to the content of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A steam turbine overspeed prevention system, comprising a steam turbine (1) and a generator (2) drivingly connected to the steam turbine (1), and further comprising an excitation device (3), wherein the excitation device (3) can apply excitation required for power generation to the generator (2), and an output line of the generator (2) is connected to a power grid (4) through a second to power grid switch (15); characterized in that: It also includes a flywheel device (5), which includes a flywheel and a flywheel motor, wherein the flywheel includes a flywheel rotor and a stator, the flywheel rotor is connected to the flywheel motor in a transmission manner, the generator (2) output line is connected to the flywheel through a flywheel device switch (12), and the flywheel can be rotated by supplying power through the generator (2), and also includes a switch (13), a bidirectional converter (7) and a first to-grid switch (14), the flywheel motor is connected to the bidirectional converter (7) through the switch (13), and the bidirectional converter (7) is connected to the grid (4) through the first to-grid switch (14).

2. A steam turbine overspeed prevention system according to claim 1, characterized in that: It also includes a battery (6) and a battery switch (11), and the bidirectional converter (7) is connected to the battery (6) via the battery switch (11).

3. A steam turbine overspeed prevention system as claimed in claim 2, characterized in that: The storage battery (6) is connected to the flywheel and can drive the flywheel to rotate.

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