Steam turbine overspeed protection system

Abstract

The present disclosure provides an overspeed protection system for a steam turbine, which relates to the technical field of steam turbine safety. At least two sets of steam turbine overspeed protection devices are installed at different positions on the gear of the steam turbine. The at least two sets of steam turbine overspeed protection devices collect the rotational speed of the gear at their respective positions, and when the rotational speeds collected by the at least two sets of steam turbine overspeed protection devices meet the overspeed condition, a control signal is sent to a switching device. The switching device responds to the control signal and controls the steam turbine to stop rotating. At least two sets of steam turbine overspeed protection devices are redundantly distributed at different positions on the gear of the steam turbine. By simultaneously collecting the rotational speeds at different positions, the redundancy of rotational speed collection is improved, so that the steam turbine can respond quickly during overspeed protection. Moreover, when some of the at least two sets of steam turbine overspeed protection devices are damaged, the other steam turbine overspeed protection devices can still continue to collect the rotational speed for overspeed protection, improving the reliability of the steam turbine overspeed protection.

Description

Technical Field

[0001] The present disclosure relates to the technical field of steam turbine safety, and particularly to a steam turbine overspeed protection system. Background Art

[0002] A steam turbine is a machine that operates at high speed under high temperature and high pressure. The rotating components thereof bear huge centrifugal forces, which are proportional to the square of the rotational speed. Therefore, as the rotational speed increases, the centrifugal force will increase rapidly. The rotor of a steam turbine is generally designed based on 115% - 120% of the rated rotational speed. Once the rotational speed exceeds its strength limit, serious accidents such as blade fracture, dynamic and static rubbing, and even shaft breakage will occur. Therefore, the rotational speed of a steam turbine is one of the most important parameters in all monitoring and protection systems of a power plant. The reliability and rationality of the steam turbine overspeed protection setting are effective guarantees for ensuring the safe, stable and economic operation of the unit. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a steam turbine overspeed protection system for overspeed protection of an operating steam turbine.

[0004] To achieve the above purpose, the present disclosure provides a steam turbine overspeed protection system, which includes: at least two sets of steam turbine overspeed protection devices installed at different positions on the gear of the steam turbine for collecting the rotational speed of the gear at their respective positions; the at least two sets of steam turbine overspeed protection devices are further configured to issue a control signal when the rotational speeds collected by the at least two sets of steam turbine overspeed protection devices meet the overspeed condition; a switching device connected to the at least two sets of steam turbine overspeed protection devices and configured to be connected to the steam turbine for controlling the steam turbine to stop rotating according to the control signal.

[0005] Optionally, the at least two sets of steam turbine overspeed protection devices are configured to issue the control signal when at least one of the rotational speeds collected by the at least two sets of steam turbine overspeed protection devices is greater than a preset rotational speed.

[0006] Optionally, the at least two sets of steam turbine overspeed protection devices include: a first steam turbine overspeed protection device; the first steam turbine overspeed protection device includes: a first speed measurement eddy current probe, a second speed measurement eddy current probe, a third speed measurement eddy current probe, and a first monitoring device; the first speed measurement eddy current probe, the second speed measurement eddy current probe, and the third speed measurement eddy current probe are installed at a first gear position; the first speed measurement eddy current probe, the second speed measurement eddy current probe, the third speed measurement eddy current probe, and the switch device are respectively connected to the first monitoring device; the first speed measurement eddy current probe, the second speed measurement eddy current probe, and the third speed measurement eddy current probe are used to measure the rotational speed at the first gear position to obtain three rotational speeds at the first gear position; the first monitoring device is used to select at least two identical rotational speeds from the three rotational speeds at the first gear position as a first target rotational speed; the first monitoring device is further used to send out the control signal when the first target rotational speed is greater than the preset rotational speed.

[0007] Optionally, the first steam turbine overspeed protection device further includes: a first preamplifier, a second preamplifier, and a third preamplifier; the first monitoring device includes: a first card, a second card, a third card, a first selection module, a first relay, a second relay, and a third relay; the first speed measurement eddy current probe is connected to the first card through the first preamplifier; the second speed measurement eddy current probe is connected to the second card through the second preamplifier; the third speed measurement eddy current probe is connected to the third card through the third preamplifier; the first card, the second card, the third card, the first relay, the second relay, and the third relay are respectively connected to the first selection module.

[0008] Optionally, the at least two sets of steam turbine overspeed protection devices further include: a second steam turbine overspeed protection device; the second steam turbine overspeed protection device includes: a first speed measurement magnetoresistive probe, a second speed measurement magnetoresistive probe, a third speed measurement magnetoresistive probe, and a second monitoring device; the first speed measurement magnetoresistive probe, the second speed measurement magnetoresistive probe, and the third speed measurement magnetoresistive probe are installed at a second gear position; the first speed measurement magnetoresistive probe, the second speed measurement magnetoresistive probe, the third speed measurement magnetoresistive probe, and the switch device are respectively connected to the second monitoring device; the first speed measurement magnetoresistive probe, the second speed measurement magnetoresistive probe, and the third speed measurement magnetoresistive probe are used to measure the rotational speed at the second gear position to obtain three rotational speeds at the second gear position; the second monitoring device is used to select at least two identical rotational speeds from the three rotational speeds at the second gear position as a second target rotational speed; the second monitoring device is further used to send out the control signal when the second target rotational speed is greater than the preset rotational speed.

[0009] Optionally, the second monitoring device includes: a first speed card, a second speed card, a third speed card, a second selection module, a first DO card, a second DO card, and a third DO card; the first speed measurement magnetoresistive probe is connected to the first speed card, the second speed measurement magnetoresistive probe is connected to the second speed card, and the third speed measurement magnetoresistive probe is connected to the third speed card; the first speed card, the second speed card, the third speed card, the first DO card, the second DO card, and the third DO card are respectively connected to the second selection module.

[0010] Optionally, the at least two sets of steam turbine overspeed protection devices further include: a third steam turbine overspeed protection device; the third steam turbine overspeed protection device includes: a fourth speed measurement magnetoresistive probe, a fifth speed measurement magnetoresistive probe, a sixth speed measurement magnetoresistive probe, a seventh speed measurement magnetoresistive probe, and a third selection module; the fourth speed measurement magnetoresistive probe, the fifth speed measurement magnetoresistive probe, the sixth speed measurement magnetoresistive probe, and the seventh speed measurement magnetoresistive probe are installed at the third gear position; the fourth speed measurement magnetoresistive probe, the fifth speed measurement magnetoresistive probe, the sixth speed measurement magnetoresistive probe, and the seventh speed measurement magnetoresistive probe are respectively connected to the third selection module; the fourth speed measurement magnetoresistive probe, the fifth speed measurement magnetoresistive probe, the sixth speed measurement magnetoresistive probe, and the seventh speed measurement magnetoresistive probe are used to measure the rotational speed at the third gear position to obtain four rotational speeds at the third gear position; the third selection module is used to select at least two identical rotational speeds from the four rotational speeds at the third gear position as the third target rotational speed; the third selection module is further used to issue the control signal when the third target rotational speed is greater than the preset rotational speed.

[0011] Optionally, the switching device includes a switch and a relay; the at least two sets of steam turbine overspeed protection devices are connected to the switch, the switch is connected to the relay, and the relay is used to be connected to the steam turbine; the switch is used to control the steam turbine to stop rotating by controlling the relay according to the control signal.

[0012] Optionally, the switch includes: a first switch; the relay includes a first protection relay; the first switch is respectively connected to the first monitoring device, the second monitoring device, and the first protection relay, and is used to be connected to the steam turbine; the first switch is used to control the steam turbine to stop rotating by controlling the first protection relay according to the control signal issued by the first monitoring device and / or the control signal issued by the second monitoring device.

[0013] Optionally, the switch device further includes a second switch; the relay further includes a second protection relay; the second switch is respectively connected to the third selection module and the second protection relay, and is used to be connected to the steam turbine; the second switch is used to control the steam turbine to stop rotating by controlling the second protection relay according to the control signal sent by the third selection module.

[0014] The steam turbine overspeed protection system provided by the present disclosure includes at least two sets of steam turbine overspeed protection devices installed at different positions on the gear of the steam turbine. The at least two sets of steam turbine overspeed protection devices collect the rotational speeds of the gears at their respective positions, and when the rotational speeds collected by the at least two sets of steam turbine overspeed protection devices meet the overspeed condition, a control signal is sent to the switch device. The switch device responds to the control signal and controls the steam turbine to stop rotating. By redundantly distributing at least two sets of steam turbine overspeed protection devices at different positions on the gear of the steam turbine, the redundancy of rotational speed collection is improved by simultaneously collecting the rotational speeds at different positions, so that the steam turbine can respond quickly during overspeed protection. Moreover, when some of the at least two sets of steam turbine overspeed protection devices are damaged, the other steam turbine overspeed protection devices can still continue to collect the rotational speed for overspeed protection, improving the reliability of the steam turbine overspeed protection.

[0015] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. They are used together with the following specific implementation to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0017] Figure 1 is a schematic diagram of a steam turbine overspeed protection system provided by an embodiment of the present disclosure;

[0018] Figure 2 is a schematic diagram of a steam turbine overspeed protection system provided by an embodiment of the present disclosure;

[0019] Figure 3 is a schematic diagram of a first steam turbine overspeed protection device provided by an embodiment of the present disclosure;

[0020] Figure 4 is a schematic diagram of a second steam turbine overspeed protection device provided by an embodiment of the present disclosure;

[0021] Figure 5 is a schematic diagram of a third steam turbine overspeed protection device provided by an embodiment of the present disclosure;

[0022] Figure 6 is a schematic diagram of the switch device;

[0023] Figure 7 It is a schematic diagram of a switch;

[0024] Figure 8 It is a schematic diagram of a switch.

[0025] Explanation of the reference numerals in the drawings

[0026] 10 - Turbine overspeed protection system; 110 - Turbine overspeed protection device; 111 - First turbine overspeed protection device; 1111 - First speed measurement eddy current probe; 1112 - Second speed measurement eddy current probe; 1113 - Third speed measurement eddy current probe; 1114 - First monitoring device; 11141 - First card; 11142 - Second card; 11143 - Third card; 11144 - First selection module; 11145 - First relay; 11146 - Second relay; 11147 - Third relay; 1115 - First preamplifier; 1116 - Second preamplifier; 1117 - Third preamplifier; 112 - Second turbine overspeed protection device; 1121 - First speed measurement magnetoresistive probe; 1122 - Second speed measurement magnetoresistive probe; 1123 - Third speed measurement magnetoresistive probe; 1124 - Second monitoring device; 11241 - First speed card; 11242 - Second speed card; 11243 - Third speed card; 11244 - Second selection module; 11245 - First DO card; 11246 - Second DO card; 11247 - Third DO card; 113 - Third turbine overspeed protection device; 1131 - Fourth speed measurement magnetoresistive probe; 1132 - Fifth speed measurement magnetoresistive probe; 1133 - Sixth speed measurement magnetoresistive probe; 1134 - Seventh speed measurement magnetoresistive probe; 120 - Switch device; 20 - Gear. Specific embodiments

[0027] The following will describe in detail the specific embodiments of the present disclosure with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present disclosure, and are not intended to limit the present disclosure.

[0028] A steam turbine is a machine that operates at high speed under high temperature and high pressure. The rotating components thereof bear huge centrifugal forces, which are proportional to the square of the rotational speed. Therefore, as the rotational speed increases, the centrifugal force will increase rapidly. The rotor of a steam turbine is generally designed based on 115% - 120% of the rated rotational speed. Once the rotational speed exceeds its strength limit, serious accidents such as blade fracture, dynamic and static rubbing, and even shaft breakage will occur. Therefore, the rotational speed of a steam turbine is one of the most important parameters in all the monitoring and protection systems of a power plant. The reliability and rationality of the steam turbine overspeed protection setting are effective guarantees for ensuring the safe, stable and economic operation of the unit.

[0029] Currently, the overspeed protection systems of steam turbines generally have drawbacks:

[0030] (1) The distribution position and number of measurement points are unreasonable, and the redundancy of protection settings is insufficient, resulting in risks of malfunction and refusal to operate.

[0031] (2) The mechanical overspeed structure is complex and inconvenient to set and adjust. Only one fails without redundancy and loses its protective function. The reliability verification is complex and early warning cannot be issued in a timely manner.

[0032] In view of the above problems, the present disclosure provides a steam turbine overspeed protection system, in which at least two redundant steam turbine overspeed protection devices are installed at different positions of the gears of the steam turbine to monitor the speed of the steam turbine, improving the accuracy of steam turbine speed monitoring and the reliability of steam turbine overspeed protection. Please refer to Figure 1 , the steam turbine overspeed protection system 10 includes: at least two steam turbine overspeed protection devices 110 and a switching device 120.

[0033] At least two steam turbine overspeed protection devices 110 are installed at different positions on the gears of the steam turbine and are used to collect the speeds of the gears at their respective positions.

[0034] Among them, at least two sets can be two sets, three sets, or even more sets. At least two steam turbine overspeed protection devices 110 are installed at different positions on the gears of the steam turbine, and at least two steam turbine overspeed protection devices 110 respectively collect the speeds of the steam turbine gears at their respective positions, improving the redundancy of speed measurement and avoiding risks such as malfunction and refusal to operate in the later stage.

[0035] Optionally, each of the at least two steam turbine overspeed protection devices 110 may have multiple probes for measuring speed, and the speed is measured by multiple probes at the same gear position, further improving the redundancy of speed measurement.

[0036] The at least two steam turbine overspeed protection devices 110 are further used to issue a control signal when the speeds collected by the at least two steam turbine overspeed protection devices meet the overspeed condition.

[0037] Among them, the control signal is used to control the on-off of the switching device 120. Optionally, the control signal can be a high-low level signal.

[0038] In one embodiment, the at least two steam turbine overspeed protection devices are used to issue the control signal when at least one of the speeds collected by the at least two steam turbine overspeed protection devices is greater than a preset speed.

[0039] The preset speed can be set according to actual safety requirements. For example, the preset speed can be 10% higher than the maximum speed of the steam turbine. For example, if the maximum speed of the steam turbine is 3000 revolutions per minute, the corresponding preset speed is 3300 revolutions per minute.

[0040] In another embodiment, when there is a preset number of rotational speeds greater than a preset rotational speed among the rotational speeds collected by at least two sets of steam turbine overspeed protection devices, a control signal is issued.

[0041] For example, the preset number can be at least half of the number of steam turbine overspeed protection devices.

[0042] The switch device 120 is connected to the at least two sets of steam turbine overspeed protection devices 110 and is used to be connected to the steam turbine, and is used to control the steam turbine to stop rotating according to the control signal.

[0043] The switch device 120 responds to the control signal and controls the power-off of the steam turbine by changing its own on-off state, so as to achieve the purpose of controlling the steam turbine to stop rotating.

[0044] In the steam turbine overspeed protection system provided in this embodiment, it includes: at least two sets of steam turbine overspeed protection devices installed at different positions on the gear of the steam turbine. The at least two sets of steam turbine overspeed protection devices collect the rotational speed of the gear at their respective positions, and when the rotational speeds collected by the at least two sets of steam turbine overspeed protection devices meet the overspeed condition, a control signal is sent to the switch device. The switch device responds to the control signal and controls the steam turbine to stop rotating. At least two sets of steam turbine overspeed protection devices are redundantly distributed at different positions of the gear of the steam turbine. By simultaneously collecting the rotational speeds at different positions, the redundancy of rotational speed collection is improved, so that the steam turbine can respond quickly during overspeed protection. Moreover, when some of the at least two sets of steam turbine overspeed protection devices are damaged, the other steam turbine overspeed protection devices can still continue to collect the rotational speed for overspeed protection, improving the reliability of steam turbine overspeed protection.

[0045] Optionally, taking three sets of at least two sets of steam turbine overspeed protection devices as an example, please refer to Figure 2 The at least two sets of steam turbine overspeed protection devices include: the first steam turbine overspeed protection device 111. Optionally, the first steam turbine overspeed protection device 111 can utilize the principle of the 100% overspeed system of TSI (Turbine Supervisory Instrumentation).

[0046] Combined with Figure 3 The first steam turbine overspeed protection device 111 includes: the first speed measurement eddy current probe 1111, the second speed measurement eddy current probe 1112, the third speed measurement eddy current probe 1113, and the first monitoring device 1114.

[0047] The first speed-measuring eddy current probe 1111, the second speed-measuring eddy current probe 1112, and the third speed-measuring eddy current probe 1113 are installed at the first gear position of the upper gear 20 of the steam turbine. For example, the first gear position is the 6 / 7 watt gear disc. The arc-shaped bracket located outside the gear is concentric and coaxial with the gear. Three speed-measuring threaded holes are provided on the surface of the bracket. The first speed-measuring eddy current probe 1111, the second speed-measuring eddy current probe 1112, and the third speed-measuring eddy current probe 1113 are respectively fixed in the three speed-measuring threaded holes, and there is a gap between the three probes and the gear surface. Since the bracket is concentric and coaxial with the gear, the first speed-measuring eddy current probe 1111, the second speed-measuring eddy current probe 1112, and the third speed-measuring eddy current probe 1113 on the bracket can measure the rotational speed of the gear. The first speed-measuring eddy current probe 1111, the second speed-measuring eddy current probe 1112, the third speed-measuring eddy current probe 1113, and the switch device 120 are respectively connected to the first monitoring device 1114.

[0048] The first speed-measuring eddy current probe 1111, the second speed-measuring eddy current probe 1112, and the third speed-measuring eddy current probe 1113 are used to measure the rotational speed at the first gear position and obtain three rotational speeds at the first gear position.

[0049] The first monitoring device 1114 is used to select at least two identical rotational speeds from the three rotational speeds at the first gear position as the first target rotational speed, which can be understood as a two-out-of-three processing. The first monitoring device 1114 is also used to send the control signal when the first target rotational speed is greater than the preset rotational speed.

[0050] Optionally, please refer to Figure 3 , the first steam turbine overspeed protection device 111 further includes: a first preamplifier 1115, a second preamplifier 1116, and a third preamplifier 1117. The first preamplifier 1115, the second preamplifier 1116, and the third preamplifier 1117 are used to amplify the signal.

[0051] The first monitoring device 1114 includes: a first card 11141, a second card 11142, a third card 11143, a first selection module 11144, a first relay 11145, a second relay 11146, and a third relay 11147.

[0052] The first speed measurement eddy current probe 1111 is connected to the first card 11141 through the first preamplifier 1115; the second speed measurement eddy current probe 1112 is connected to the second card 11142 through the second preamplifier 1116; the third speed measurement eddy current probe 1113 is connected to the third card 11143 through the third preamplifier 1117; the first card 11141, the second card 11142, the third card 11143, the first relay 11145, the second relay 11146, and the third relay 11147 are respectively connected to the first selection module 11144.

[0053] In Figure 3 In it, the first speed measurement eddy current probe 1111 collects the rotational speed at the first position and sends the rotational speed to the first preamplifier 1115. After amplifying the rotational speed signal sent by the first speed measurement eddy current probe 1111, the first preamplifier sends it to the first card 11141, and the amplified rotational speed signal is sent to the first selection module 11144 through the first card 11141. While the first speed measurement eddy current probe 1111 is collecting the rotational speed, the second speed measurement eddy current probe 1112 and the third speed measurement eddy current probe 1113 are also collecting the rotational speed at the first position. The second speed measurement eddy current probe 1112 collects the rotational speed at the first position and sends the rotational speed to the second preamplifier 1116. After amplifying the rotational speed signal sent by the second speed measurement eddy current probe 1112, the second preamplifier sends it to the second card 11142, and the amplified rotational speed signal is sent to the first selection module 11144 through the second card 11142. The third speed measurement eddy current probe 1113 collects the rotational speed at the first position and sends the rotational speed to the third preamplifier 1117. After amplifying the rotational speed signal sent by the third speed measurement eddy current probe 1113, the third preamplifier sends it to the third card 11143, and the amplified rotational speed signal is sent to the first selection module 11144 through the third card 11143. After receiving the three-way rotational speed signals, the first selection module 11144 selects at least two identical rotational speed signals from the three-way rotational speed signals as the first target rotational speed. It can be understood that when there are two identical rotational speed signals among the three-way rotational speed signals, the rotational speed corresponding to the two identical rotational speed signals is used as the first target rotational speed. When the three-way rotational speed signals are all the same, the rotational speed corresponding to the three-way rotational speed signals is used as the first target rotational speed. When the first target rotational speed is greater than the preset rotational speed, the first selection module 11144 generates a control signal and sends the notification signal to the switching device through the first relay 11145, the second relay 11146, and the third relay 11147.

[0054] Optionally, the first selection module 11144 may be, but is not limited to, a GPU (Graphics Processing Unit), a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a SOC (System on Chip), a controller, a microcontroller, a microprocessor, a single-chip microcomputer, etc.

[0055] Please continue to refer to Figure 2 , the at least two sets of turbine overspeed protection devices 110 further include: a second turbine overspeed protection device 112. Optionally, the second turbine overspeed protection device 112 may be based on the operating principle of 110% overspeed of the DEH (Digital Electric Hydraulic control system).

[0056] Combined with Figure 4 , the second turbine overspeed protection device 112 includes: a first speed measurement magnetoresistive probe 1121, a second speed measurement magnetoresistive probe 1122, a third speed measurement magnetoresistive probe 1123, and a second monitoring device 1124;

[0057] The first speed measurement magnetoresistive probe 1121, the second speed measurement magnetoresistive probe 1122, and the third speed measurement magnetoresistive probe 1123 are installed at the second gear position, and the second gear position may be a 2 / 3 watt gear disk. The arc-shaped bracket outside the gear is concentric and coaxial with the gear. Three speed measurement threaded holes are opened on the surface of the bracket, and the first speed measurement magnetoresistive probe 1121, the second speed measurement magnetoresistive probe 1122, and the third speed measurement magnetoresistive probe 1123 are respectively fixed in the three speed measurement threaded holes, and there is a gap between the three probes and the gear surface. Since the bracket is concentric and coaxial with the gear, the first speed measurement magnetoresistive probe 1121, the second speed measurement magnetoresistive probe 1122, and the third speed measurement magnetoresistive probe 1123 on the bracket can measure the rotational speed of the gear at the first position. The first speed measurement magnetoresistive probe 1121, the second speed measurement magnetoresistive probe 1122, the third speed measurement magnetoresistive probe 1123, and the switch device 120 are respectively connected to the second monitoring device 1124;

[0058] The first speed measurement magnetoresistive probe 1121, the second speed measurement magnetoresistive probe 1122, and the third speed measurement magnetoresistive probe 1123 are used to measure the rotational speed at the position of the second gear and obtain three rotational speeds at the position of the second gear.

[0059] The second monitoring device 1124 is configured to select at least two identical rotational speeds from the three rotational speeds at the position of the second gear as the second target rotational speed.

[0060] The second monitoring device 1124 is further configured to send the control signal when the second target rotational speed is greater than the preset rotational speed.

[0061] Please continue to refer to Figure 4 , the second monitoring device 1124 includes: a first rotational speed card 11241, a second rotational speed card 11242, a third rotational speed card 11243, a second selection module 11244, a first DO card 11245, a second DO card 11246, and a third DO card 11247.

[0062] The first speed measurement magnetoresistive probe 1121 is connected to the first rotational speed card 11241, the second speed measurement magnetoresistive probe 1122 is connected to the second rotational speed card 11242, and the third speed measurement magnetoresistive probe 1123 is connected to the third rotational speed card 11243. The first rotational speed card 11241, the second rotational speed card 11242, the third rotational speed card 11243, the first DO card 11245, the second DO card 11246, and the third DO card 11247 are respectively connected to the second selection module 11244.

[0063] The first speed measurement magnetoresistive probe 1121, the second speed measurement magnetoresistive probe 1122, and the third speed measurement magnetoresistive probe 1123 simultaneously measure the rotational speed at the position of the second gear. The rotational speed of the first speed measurement magnetoresistive probe 1121 is sent to the second selection module 11244 through the first rotational speed card 11241, the rotational speed of the second speed measurement magnetoresistive probe 1122 is sent to the second selection module 11244 through the second rotational speed card 11242, and the rotational speed of the third speed measurement magnetoresistive probe 1123 is sent to the second selection module 11244 through the third rotational speed card 11243. Sent to the second selection module 11244, the second selection module 11244 selects at least two identical rotational speeds from the three rotational speeds as the second target rotational speed, which can be understood as a two-out-of-three processing. When the second selection module 11244 determines that the second target rotational speed is greater than the preset rotational speed, it generates a control signal and sends the control signal to the switching device through the first DO card 11245, the second DO card 11246, and the third DO card 11247.

[0064] Optionally, the second selection module 11244 may be, but is not limited to, a GPU, a CPU, an FPGA, a DSP, an ASIC, an SOC, a controller, a microcontroller, a microprocessor, a single-chip microcomputer, etc.

[0065] Optionally, refer to Figure 2 , the at least two sets of steam turbine overspeed protection devices further include: a third steam turbine overspeed protection device 113.

[0066] Refer to Figure 5 , the third steam turbine overspeed protection device 113 includes: a fourth speed measuring magnetoresistive probe 1131, a fifth speed measuring magnetoresistive probe 1132, a sixth speed measuring magnetoresistive probe 1133, a seventh speed measuring magnetoresistive probe 1134, and a third selection module (not shown in the figure).

[0067] The fourth speed measuring magnetoresistive probe 1131, the fifth speed measuring magnetoresistive probe 1132, the sixth speed measuring magnetoresistive probe 1133, and the seventh speed measuring magnetoresistive probe 1134 are installed at the third gear position, and the third gear position may be the front box gear disk. The fourth speed measuring magnetoresistive probe 1131, the fifth speed measuring magnetoresistive probe 1132, the sixth speed measuring magnetoresistive probe 1133, and the seventh speed measuring magnetoresistive probe 1134 are respectively connected to the third selection module.

[0068] The fourth speed measuring magnetoresistive probe 1131, the fifth speed measuring magnetoresistive probe 1132, the sixth speed measuring magnetoresistive probe 1133, and the seventh speed measuring magnetoresistive probe 1134 are used to measure the rotational speed at the third gear position and obtain four rotational speeds at the third gear position.

[0069] The third selection module is used to select at least two identical rotational speeds from the four rotational speeds at the third gear position as the third target rotational speed. It can be understood as a four-select-two process. For example, when two of the four rotational speeds are the same, the two identical rotational speeds are used as the third target rotational speed. When three of the four rotational speeds are the same, the three identical rotational speeds are used as the third target rotational speed. When all four of the four rotational speeds are the same, the four identical rotational speeds are used as the third target rotational speed.

[0070] The third selection module is further used to issue the control signal when the third target rotational speed is greater than the preset rotational speed.

[0071] Optionally, refer to Figure 5, the third steam turbine overspeed protection device 113 further includes: a control cabinet, in which there are 4 tachometers, namely n1, n2, n3, and n4. The 4 tachometers are respectively connected to each of the fourth speed measurement reluctance probe 1131, the fifth speed measurement reluctance probe 1132, the sixth speed measurement reluctance probe 1133, and the seventh speed measurement reluctance probe 1134, and are used to display the rotational speed measured by the speed measurement probe connected to each of them. The 4 tachometers can output analog signals to the DCS (Distributed Control System) control system for easy monitoring.

[0072] There are also two double-button switches K1 and K2 in the control cabinet. There are also four rotary switches K3, K4, K5, and K6. The double-button switch K1 and the double-button switch K2 are used for the action experiment of the switching device, that is, when the double-button switch K1 and the double-button switch K2 are pressed simultaneously, the steam turbine stops rotating. Or the rotary switches K3, K4, K5, and K6 are used for the action experiment of the switching device, that is, when the rotary switches K3, K4, K5, and K6 are pressed simultaneously, the steam turbine stops rotating.

[0073] It also uses two-way 220VAC and two-way 220VDC power supplies. One of the two-way 220VAC is used to supply power to the tachometer n1 and the tachometer n2, and the other is used to supply power to the tachometer n3 and the tachometer n4. The two-way 220VDC power supply is used to supply power to the switching device. The power indicator lights L1 and L2 are used to indicate the working status of 220VAC, and the power indicator lights L3 and L4 are used to indicate the working status of 220VDC.

[0074] It should be noted that the number of at least two sets of steam turbine overspeed protection devices is determined according to the number of specific points to be monitored, not limited to Figure 3 the three sets in, and it can also be a smaller number, such as two sets. For example, at least two sets of steam turbine overspeed protection devices include the first steam turbine overspeed protection device and the second steam turbine overspeed protection device, or include the first steam turbine overspeed protection device and the third steam turbine overspeed protection device, or include the second steam turbine overspeed protection device and the third steam turbine overspeed protection device. At least two sets of steam turbine overspeed protection devices can also be a larger number, such as four sets, five sets, etc.

[0075] Optionally, the switching device includes a switch and a relay; the at least two sets of steam turbine overspeed protection devices are connected to the switch, the switch is connected to the relay, and the relay is used to be connected to the steam turbine; the switch is used to control the steam turbine to stop rotating by controlling the relay according to the control signal.

[0076] Optionally, the switching device can also be redundant. For example, the switch includes: a first switch; the relay includes a first protection relay. The first switch is respectively connected to the first monitoring device, the second monitoring device, and the first protection relay, and is used to connect to the steam turbine.

[0077] Please refer to Figure 6 and Figure 7 , the first switch includes switches KA1, KA2, KA3, and KA4, and the first protection relay includes relays AST1, AST2, AST3, and AST4. After switch KA1 is connected in series with relay AST1, it is connected in parallel with the series connection of switch KA2 and relay AST2. Similarly, after switch KA3 is connected in series with relay AST3, it is connected in parallel with the series connection of switch KAT4 and relay AST4.

[0078] The first switch is used to control the steam turbine to stop rotating by controlling the first protection relay according to the control signal sent by the first monitoring device and / or the control signal sent by the second monitoring device.

[0079] Combined with Figure 6 and Figure 7 , relays AST1, AST2, AST3, and AST4 are normally open relays. When not energized, relays AST1, AST2, AST3, and AST4 are all open. When switch KA1 is closed, relay AST1 is energized and closed. When switch KA2 is closed, relay AST2 is energized and closed. When switch KA3 is closed, relay AST3 is energized and closed. When switch KA4 is closed, relay AST4 is energized and closed. The two-or-one-and control method is adopted, that is, when relay AST1 or relay AST3 is energized, and when relay AST2 or relay AST4 is energized, the steam turbine is shut off and the steam turbine stops rotating.

[0080] The switching device further includes a second switch, and the relay further includes a second protection relay.

[0081] The second switch is respectively connected to the third selection module and the second protection relay, and is used to connect to the steam turbine.

[0082] Please refer to Figure 6 and Figure 8 , the second switch includes switches K11, K12, K13, K14, K21, K22, K23, K24, K31, K32, K33, K34, K41, K42, K43, and K44. The second protection relay includes relays AST5, AST6, AST7, and AST8.

[0083] As Figure 6As shown, after switches K11 and K12 are connected in series, they are respectively connected in parallel with switches K13 and K14. After the three branches are connected in parallel, they are connected to relay AST5. After switches K21 and K22 are connected in series, they are respectively connected in parallel with switches K23 and K24. After the three branches are connected in parallel, they are connected to relay AST6.

[0084] Similarly, after switches K31 and K32 are connected in series, they are respectively connected in parallel with switches K33 and K34. After the three branches are connected in parallel, they are connected to relay AST7. After switches K41 and K42 are connected in series, they are respectively connected in parallel with switches K43 and K44. After the three branches are connected in parallel, they are connected to relay AST8.

[0085] The second switch is used to control the stop of the steam turbine by controlling the second protection relay according to the control signal sent by the third selection module.

[0086] Combined Figure 6 and Figure 8 , relays AST5, AST6, AST7, and AST8 are normally closed relays. When not energized, relays AST5, AST6, AST7, and AST8 are all closed. Switches K14, K24, K34, and K34 are automatically controlled according to the control signal. When switch K14 is closed, relay AST5 is energized and disconnected. When switch K24 is closed, relay AST6 is energized and disconnected. When switch K34 is closed, relay AST7 is energized and disconnected. When switch K44 is closed, relay AST8 is energized and disconnected. The two-or-one-and control method is adopted, that is, when relay AST5 or relay AST6 is closed, and when relay AST7 or relay AST8 is closed, the steam turbine is shut off and the steam turbine stops rotating.

[0087] The pressure at point P1 is about 14 Mpa. The pressure at point P2 is about 7 Mpa through throttle holes J1 and J2. During the test, solenoid valves AST1 or AST3 act, causing the pressure at point P2 to rise to about 14 Mpa. If solenoid valves AST2 or AST4 act, the pressure at point P2 drops to 0 Mpa. The set values of pressure switches ASP1 and ASP2 are ASP1: 9.5 Mpa and ASP2: 4.5 Mpa respectively. When the channel 1 (AST1 or AST3) acts in the test, ASP1 acts; when the channel 2 (AST2 or AST4) acts in the test, ASP2 acts; ASP1 and ASP2 respectively send indication signals to the ETS control system for monitoring, and the action of the solenoid valve is judged by the pressure change of ASP1 and ASP2. The ASP3 pressure gauge is used for local display for easy observation.

[0088] The pressure at point P1 is about 14Mpa, and the pressure at point P3 is about 7Mpa through the throttle holes J3 and J4. During the test, the solenoid valve AST5 or AST7 is actuated, causing the pressure at point P3 to rise to about 14Mpa. If the solenoid valve AST6 or AST8 is actuated, the pressure at point P3 drops to 0Mpa. The setting values ​​of the pressure switches ASP4 and ASP5 are ASP4: 9.5Mpa and ASP5: 4.5Mpa respectively. When the channel 3 (AST5 or AST7) is actuated for the test, ASP4 is actuated; when the channel 4 (AST6 or AST8) is actuated for the test, ASP5 is actuated; ASP4 and ASP5 send indication signals to the DCS control system for easy monitoring, and the actuation of the solenoid valve is judged by the pressure changes of ASP4 and ASP5. The ASP6 pressure gauge is used for local display for easy observation.

[0089] The AST protection solenoid valve components are centrally designed and arranged. One set of AST solenoid valves adopts a "two or one and" design (power-on action), and together with another set of AST solenoid valves adopts a "two or one and" design (power-off action), they form an emergency tripping circuit. If any set of solenoid valves is actuated, the unit will trip, which can effectively prevent false operation and improve the safety of the unit.

[0090] The first solenoid valve group action circuit (solenoid valve opens when power is lost, and operates when power is lost): the first 220VDC power supply is equipped with solenoid valves AST1 and AST3, and the second 220VDC power supply is equipped with solenoid valves AST2 and AST4. When any 220VDC power supply is lost, the steam turbine will not be cut off to prevent the unit protection from malfunctioning. KA1, KA2, KA3, and KA4 are the open contacts of the ETS system relay output, which correspond to the four AST1, AST2, AST3, and AST4 solenoid valves one by one, and the four AST1, AST2, AST3, and AST4 solenoid valves can be tested separately. When the steam turbine is operating normally, KA1, KA2, KA3, and KA4 are closed, and the four AST1, AST2, AST3, and AST4 solenoid valves are energized and closed. When there is a protection action signal that meets the soft circuit (TSI 110% overspeed, DEH 110% overspeed, low lubricating oil pressure, low vacuum, etc.), the KA1, KA2, KA3, and KA4 relay outputs are disconnected, the four AST1, AST2, AST3, and AST4 solenoid valves are de-energized and opened, the oil pressure is released, and all valves are closed to shut down the steam turbine; when the two buttons on the operating console are pressed at the same time, the four AST1, AST2, AST3, and AST4 solenoid valves are de-energized and opened, including hard circuits and soft circuits; the four solenoid valves are "two or one and" in the local oil circuit, and at least one of AST1 and AST3 is actuated and at least one of AST2 and AST4 is actuated.

[0091] Second solenoid valve group action circuit (solenoid valve is energized to open and act): The first 220VDC power supply drives solenoid valves AST5 and AST6, and the second 220VDC power supply drives solenoid valves AST7 and AST8. When any 220VDC power supply loses power, the turbine protection will not be lost, effectively preventing the unit protection from malfunctioning. When the rotational speed reaches the set high limit (3300), K14, K24, K34, and K44 close, and AST5, AST7, AST6, and AST8 are energized. The solenoid valve is energized to open and shuts down the turbine. When the rotational speed reaches the set high limit (3300), the two-out-of-four protection acts, and at least one of K14 and K34 reaches the set high limit and at least one of K24 and K44 reaches the set high limit. Switches K13, K23, K33, and K43 are used for individual action tests of solenoid valves AST5, AST7, AST6, and AST8. When the double buttons K1 and K2 are pressed simultaneously, the four solenoid valves AST5, AST6, AST7, and AST8 are energized to open. The four solenoid valves are "two OR one AND" in the local oil circuit, and at least one of AST5 and AST7 acts AND at least one of AST6 and AST8 acts.

[0092] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0093] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure does not separately describe various possible combination methods.

[0094] In addition, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A steam turbine overspeed protection system, characterized in that, The steam turbine overspeed protection system includes: At least two sets of steam turbine overspeed protection devices, which are installed at different positions on the gears of the steam turbine and are used to collect the rotational speeds of the gears at their respective positions; The at least two sets of steam turbine overspeed protection devices are further used to issue a control signal when at least one of the rotational speeds collected by the at least two sets of steam turbine overspeed protection devices is greater than a preset rotational speed; A switch device, which is connected to the at least two sets of steam turbine overspeed protection devices and is used to be connected to the steam turbine, and is used to control the steam turbine to stop rotating according to the control signal; The at least two sets of steam turbine overspeed protection devices include: a first steam turbine overspeed protection device and a second steam turbine overspeed protection device; The first steam turbine overspeed protection device includes: a first speed measurement eddy current probe, a second speed measurement eddy current probe, a third speed measurement eddy current probe, and a first monitoring device; The first speed measurement eddy current probe, the second speed measurement eddy current probe, and the third speed measurement eddy current probe are installed at a first gear position; the first speed measurement eddy current probe, the second speed measurement eddy current probe, the third speed measurement eddy current probe, and the switch device are respectively connected to the first monitoring device; The first speed measurement eddy current probe, the second speed measurement eddy current probe, and the third speed measurement eddy current probe are used to measure the rotational speed at the first gear position and obtain three rotational speeds at the first gear position; The first monitoring device is used to select at least two identical rotational speeds from the three rotational speeds at the first gear position as a first target rotational speed; The first monitoring device is further used to issue the control signal when the first target rotational speed is greater than the preset rotational speed; the second steam turbine overspeed protection device includes: a first speed measurement magnetoresistive probe, a second speed measurement magnetoresistive probe, a third speed measurement magnetoresistive probe, and a second monitoring device; The first speed measurement magnetoresistive probe, the second speed measurement magnetoresistive probe, and the third speed measurement magnetoresistive probe are installed at a second gear position; the first speed measurement magnetoresistive probe, the second speed measurement magnetoresistive probe, the third speed measurement magnetoresistive probe, and the switch device are respectively connected to the second monitoring device; The first speed measurement magnetoresistive probe, the second speed measurement magnetoresistive probe, and the third speed measurement magnetoresistive probe are used to measure the rotational speed at the second gear position and obtain three rotational speeds at the second gear position; The second monitoring device is used to select at least two identical rotational speeds from the three rotational speeds at the second gear position as a second target rotational speed; The second monitoring device is further used to issue the control signal when the second target rotational speed is greater than the preset rotational speed.

2. The system according to claim 1, wherein The first steam turbine overspeed protection device further includes: a first preamplifier, a second preamplifier, and a third preamplifier; The first monitoring device includes: a first card, a second card, a third card, a first selection module, a first relay, a second relay, and a third relay; The first speed-measuring eddy current probe is connected to the first card through the first preamplifier; the second speed-measuring eddy current probe is connected to the second card through the second preamplifier; the third speed-measuring eddy current probe is connected to the third card through the third preamplifier; The first card, the second card, the third card, the first relay, the second relay, and the third relay are respectively connected to the first selection module.

3. The system according to claim 1, characterized in that, The second monitoring device includes: a first speed card, a second speed card, a third speed card, a second selection module, a first DO card, a second DO card, and a third DO card; The first speed-measuring magnetoresistive probe is connected to the first speed card, the second speed-measuring magnetoresistive probe is connected to the second speed card, and the third speed-measuring magnetoresistive probe is connected to the third speed card; The first speed card, the second speed card, the third speed card, the first DO card, the second DO card, and the third DO card are respectively connected to the second selection module.

4. The system according to claim 1, wherein The at least two sets of steam turbine overspeed protection devices further include: a third steam turbine overspeed protection device; The third steam turbine overspeed protection device includes: a fourth speed-measuring magnetoresistive probe, a fifth speed-measuring magnetoresistive probe, a sixth speed-measuring magnetoresistive probe, a seventh speed-measuring magnetoresistive probe, and a third selection module; The fourth speed-measuring magnetoresistive probe, the fifth speed-measuring magnetoresistive probe, the sixth speed-measuring magnetoresistive probe, and the seventh speed-measuring magnetoresistive probe are installed at the third gear position; the fourth speed-measuring magnetoresistive probe, the fifth speed-measuring magnetoresistive probe, the sixth speed-measuring magnetoresistive probe, and the seventh speed-measuring magnetoresistive probe are respectively connected to the third selection module; The fourth speed-measuring magnetoresistive probe, the fifth speed-measuring magnetoresistive probe, the sixth speed-measuring magnetoresistive probe, and the seventh speed-measuring magnetoresistive probe are used to measure the rotational speeds at the third gear position and obtain four rotational speeds at the third gear position; The third selection module is used to select at least two identical rotational speeds from the four rotational speeds at the third gear position as the third target rotational speeds; The third selection module is further used to issue the control signal when the third target rotational speed is greater than the preset rotational speed.

5. The system according to claim 4, characterized in that, The switch device includes a switch and a relay; The at least two sets of steam turbine overspeed protection devices are connected to the switch, the switch is connected to the relay, and the relay is used to be connected to the steam turbine; The switch is used to control the steam turbine to stop rotating by controlling the relay according to the control signal.

6. The system according to claim 5, characterized in that The switch includes: a first switch; the relay includes a first protection relay; The first switch is respectively connected to the first monitoring device, the second monitoring device, and the first protection relay, and is used to be connected to the steam turbine; The first switch is used to control the steam turbine to stop rotating by controlling the first protection relay according to the control signal issued by the first monitoring device and / or the control signal issued by the second monitoring device.

7. The system according to claim 5, wherein The switch device further includes a second switch; the relay further includes a second protection relay; The second switch is respectively connected to the third selection module and the second protection relay, and is used to be connected to the steam turbine; The second switch is used to control the steam turbine to stop rotating by controlling the second protection relay according to the control signal sent by the third selection module.

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