An overspeed protection device, method, and test method

Abstract

This invention discloses an overspeed protection device, method, and testing method. The device includes a first oil circuit, a second oil circuit, and a third oil circuit connected in parallel at the oil inlet and oil outlet. A first solenoid valve and a second solenoid valve are connected in series on the first oil circuit. A third solenoid valve and a fourth solenoid valve are connected in series on the second oil circuit. A first orifice plate and a second orifice plate are connected in series on the third oil circuit. The oil circuits between the first and second solenoid valves, between the third and fourth solenoid valves, and between the first and second orifice plates are connected through an intermediate oil circuit. This invention reduces the equipment failure rate and improves the reliability of the protection device by using two oil circuits with solenoid valves. A pressure transmitter installed between the two solenoid valves on the same oil circuit detects oil pressure changes, quickly and effectively identifying the operating status of each component of the actuator, promptly detecting equipment faults, and preventing equipment accidents.

Description

Technical Field

[0001] This invention relates to the field of overspeed protection technology, and in particular to an overspeed protection device, method, and testing method, applicable to dual electronic overspeed protection for various turbines. Background Technology

[0002] Overspeed protection is an important protection against runaway in turbines. It is typically configured with one set of mechanical overspeed device and one set of electronic overspeed protection device. Considering the high reliability of the mechanical overspeed device, it is designed as the main overspeed protection, while the electronic overspeed protection is designed as an auxiliary protection.

[0003] Because mechanical overspeed testing is an online overspeed test, it causes significant damage to the rotating parts of the turbine, and the test process involves speed adjustments that result in multiple tests, which seriously affects its service life. Therefore, it is also called a destructive test. Consequently, mechanical overspeed devices no longer meet the requirements for safe and stable operation of equipment. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide an overspeed protection device, method, and test method that overcomes or at least partially solves the above problems.

[0005] Firstly, an overspeed protection device is provided, comprising:

[0006] The first oil circuit, the second oil circuit, and the third oil circuit are connected in parallel at the oil inlet and oil outlet ends.

[0007] A first solenoid valve and a second solenoid valve are connected in series in the first oil circuit;

[0008] A third solenoid valve and a fourth solenoid valve are connected in series in the second oil circuit;

[0009] The third oil line is provided with a first orifice plate and a second orifice plate connected in series.

[0010] The first solenoid valve and the second solenoid valve are connected to the first speed measuring device through the first control module;

[0011] The third solenoid valve and the fourth solenoid valve are connected to the second speed measuring device through the second control module;

[0012] The oil passages between the first and second solenoid valves, the third and fourth solenoid valves, and the first and second orifice plates are connected by an intermediate oil passage.

[0013] Optionally, a first local pressure gauge and a first pressure transmitter are installed on the intermediate oil line.

[0014] Optionally, a second local pressure gauge and a second pressure transmitter are provided at the oil inlet end.

[0015] Optionally, the oil inlet end is equipped with a first pressure switch, a second pressure switch, and a third pressure switch.

[0016] Optionally, the first speed measuring device and the second speed measuring device are integrated into the overspeed control box; the first speed measuring device and the second speed measuring device are respectively connected to three tachometers.

[0017] Optionally, the aperture of the second orifice plate is smaller than that of the first orifice plate.

[0018] Optionally, the return oil end is connected to the first solenoid valve, the third solenoid valve, and the first orifice plate respectively; the incoming oil end is connected to the second solenoid valve, the fourth solenoid valve, and the second orifice plate respectively.

[0019] Secondly, a method for overspeed protection using the overspeed protection device of the first aspect is provided, comprising:

[0020] The first speed measuring device connects the speed signal to the first control module and outputs an overspeed action signal to drive the first solenoid valve and the second solenoid valve on the first oil circuit to open, so that the emergency oil at the oil end can be depressurized to the oil return end through the first oil circuit.

[0021] The second speed measuring device connects the speed signal to the second control module, outputs an overspeed action signal, and drives the third and fourth solenoid valves on the second oil circuit to open, so that the emergency oil at the future oil end can be depressurized to the return oil end through the second oil circuit.

[0022] Optionally, during the period when the emergency oil is depressurized through the first oil circuit to the return oil end, the first pressure transmitter connected to the intermediate oil circuit and the second pressure transmitter connected to the oil inlet end issue a low pressure alarm.

[0023] During the period when the accident oil is depressurized through the second oil circuit to the return oil end, the first pressure transmitter connected to the intermediate oil circuit and the second pressure transmitter connected to the incoming oil end issue a low pressure alarm.

[0024] Thirdly, a method for testing the overspeed protection device of the first aspect is provided, characterized in that it includes:

[0025] The simulated speed signal is abnormally transmitted to the first solenoid valve. The first solenoid valve is energized and opened. The value of the first transmitter set in the intermediate oil circuit decreases and a low pressure alarm is issued. The first solenoid valve is normal.

[0026] The simulated speed signal is abnormally transmitted to the second solenoid valve. The second solenoid valve is energized and opens. The value of the first transmitter increases and issues a high pressure alarm. The second solenoid valve is normal.

[0027] The simulated speed signal is abnormally transmitted to the third solenoid valve, the third solenoid valve is energized and opened, the value of the first transmitter decreases and a low pressure alarm is issued, and the third solenoid valve is normal.

[0028] The simulated speed signal is abnormally transmitted to the fourth solenoid valve, which is then energized and opened. The value of the first transmitter increases, triggering a high pressure alarm. The fourth solenoid valve is now functioning normally.

[0029] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0030] The overspeed protection device, method, and testing method provided in this invention, on the one hand, reduce the equipment failure rate and the possibility of overspeed failure by using two oil circuits with solenoid valves, thereby improving the reliability of the protection device. On the other hand, by using a pressure transmitter installed between the two solenoid valves on the same oil circuit to detect oil pressure changes, the operating status of each component of the actuator can be quickly and effectively detected, allowing for timely detection of equipment faults and preventing equipment accidents. The device of this invention can realize online testing of the electrical overspeed protection device, and can sequentially perform online testing on four solenoid valves of two sets of devices to ensure the reliability and effectiveness of the overspeed protection device. The pressure transmitter adds low pressure and high pressure alarms, allowing for rapid identification of equipment fault points. The device of this invention has high equipment reliability, can eliminate or reduce the frequency of mechanical overspeed testing, reduce damage to the rotating parts of the turbine caused by mechanical overspeed testing, and extend the service life of the equipment.

[0031] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 This is a schematic diagram of the overspeed protection device in an embodiment of the present invention;

[0034] Figure 2 This is a logic diagram of the overspeed protection method in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the online test logic for the overspeed protection device in an embodiment of the present invention. Detailed Implementation

[0036] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings.

[0037] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0038] In the context of this disclosure, when a layer / component is referred to as being "above" another layer / component, that layer / component may be directly above the other layer / component, or there may be an intermediate layer / component between them. Additionally, if a layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component may be "below" the other layer / component. In the context of this disclosure, similar or identical components may be denoted by the same or similar reference numerals.

[0039] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to specific implementation methods. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0040] This invention provides an overspeed protection device; please refer to [the relevant documentation]. Figure 1 , Figure 1 The diagram below illustrates an overspeed protection device in an embodiment of the present invention. It includes: a first oil circuit, a second oil circuit, and a third oil circuit connected in parallel at the oil inlet and oil outlet; a first solenoid valve 1 and a second solenoid valve 2 connected in series on the first oil circuit; a third solenoid valve 3 and a fourth solenoid valve 4 connected in series on the second oil circuit; a first orifice plate 19 and a second orifice plate 20 connected in series on the third oil circuit; the first solenoid valve 1 and the second solenoid valve 2 connected to a first speed measuring device 22 via a first control module; the third solenoid valve 3 and the fourth solenoid valve 4 connected to a second speed measuring device 23 via a second control module; wherein the oil circuit between the first solenoid valve 1 and the second solenoid valve 2, the oil circuit between the third solenoid valve 3 and the fourth solenoid valve 4, and the oil circuit between the first orifice plate 19 and the second orifice plate 20 are connected via an intermediate oil circuit.

[0041] Overspeed protection is a crucial safeguard against turbine runaway. Conventionally, it consists of one mechanical overspeed device and one electronic overspeed protection device. When the set speed is exceeded, the overspeed control module activates the trip solenoid valve, releasing the safety oil pressure and causing the main valve to close, resulting in turbine tripping. This design suffers from potential problems such as probe malfunction, module failure, or solenoid valve malfunction, which are difficult to detect and reduce reliability. This is the key reason why the electronic overspeed device cannot be used as the primary overspeed protection. Considering the high reliability of the mechanical overspeed device, it is designed as the primary overspeed protection, with electronic overspeed as an auxiliary protection. The overspeed protection device provided in this invention reduces the equipment failure rate and the possibility of overspeed malfunction by setting two sets of speed measuring devices connected in parallel to two sets of oil circuits. This improves the reliability of the protection device, avoids damage to the equipment from mechanical overspeed testing, and extends the service life of the turbine. Furthermore, the device has a simple structure and low cost.

[0042] Based on the same inventive concept, this invention also provides an overspeed protection method. Please refer to [link / reference]. Figure 2 , Figure 2 The above diagram illustrates the logic principle of the overspeed protection method in this embodiment of the invention. The first speed measuring device 22 connects the first speed signal to the first control module. When the first speed signal exceeds the standard 3270, it outputs an overspeed action signal, energizing the first solenoid valve 1 and the second solenoid valve 2. Both solenoid valves 1 and 2 are simultaneously energized, opening the first oil circuit, allowing emergency oil to return, activating the main valve, and tripping the unit. The second speed measuring device 23 connects the second speed signal to the second control module. When the second speed signal exceeds the standard 3270, it outputs an overspeed action signal, energizing the third solenoid valve 3 and the fourth solenoid valve 4. Both solenoid valves 3 and 4 are simultaneously energized, opening the second oil circuit, allowing emergency oil to return, activating the main valve, and tripping the unit.

[0043] In alternative implementations, such as Figure 1 As shown, a first local pressure gauge 5 and a first pressure transmitter 6 are installed between the oil inlet and outlet ends; specifically, the first local pressure gauge 5 and the first pressure transmitter 6 are connected to the intermediate oil circuit. During overspeed protection, when the fault oil at the oil inlet is depressurized to the oil outlet end through the first or second oil circuit, the first pressure transmitter 6 will issue a low-pressure alarm. When the equipment is operating normally, the fault point can be quickly identified through the first pressure transmitter 6. When the value of the first pressure transmitter 6 is lower than the low alarm value, a low pressure alarm is issued, which can confirm the fault of the first solenoid valve 1 and the third solenoid valve 3; when the value of the first pressure transmitter 6 is higher than the high alarm value, a high pressure alarm is issued, which can confirm the fault of the second solenoid valve 2 and the fourth solenoid valve 4. The first pressure transmitter 6 can quickly and effectively detect the operating status of each component of the actuator, promptly detect equipment faults, and avoid equipment accidents.

[0044] In an optional embodiment, a second local pressure gauge 7 and a second pressure transmitter 8 are installed at the oil inlet end. During the period when the emergency oil is depressurized through the first oil circuit to the oil return end, the low emergency oil pressure causes both the first pressure transmitter 6 and the second pressure transmitter 8 to issue a low emergency oil pressure trip alarm. During the period when the emergency oil is depressurized through the second oil circuit to the oil return end, the low emergency oil pressure causes both the first pressure transmitter 6 and the second pressure transmitter 8 to issue a low emergency oil pressure trip alarm. That is, during the overspeed protection process, when the emergency oil at the oil inlet is depressurized through either the first or second oil circuit to the oil return end, both the second pressure transmitter 8 and the first pressure transmitter 6 will issue a low pressure alarm.

[0045] Based on the same inventive concept, embodiments of the present invention also provide a method for testing an overspeed protection device, such as... Figure 3 As shown, Figure 3 This is a schematic diagram of the online testing logic for the overspeed protection device in an embodiment of the present invention, including:

[0046] Simulated overspeed signal 1 is transmitted to the first solenoid valve 1, energizing and opening it. The reading on the first pressure transmitter 6 decreases, triggering a low pressure alarm. The first solenoid valve 1 is functioning normally. Simulated speed signal malfunction is transmitted to the second solenoid valve 2, energizing and opening it. The reading on the first pressure transmitter 6 increases, triggering a high pressure alarm. The second solenoid valve 2 is functioning normally. Simulated speed signal malfunction is transmitted to the third solenoid valve 3, energizing and opening it. The reading on the first pressure transmitter 6 decreases, triggering a low pressure alarm. The third solenoid valve 3 is functioning normally. Simulated speed signal malfunction is transmitted to the fourth solenoid valve 4, energizing and opening it. The reading on the first pressure transmitter 6 increases, triggering a high pressure alarm. The fourth solenoid valve 4 is functioning normally. By sequentially conducting online tests on the four solenoid valves of the two sets of devices, module or solenoid valve malfunctions can be detected early, quickly identifying equipment fault points. This improves the reliability and effectiveness of the electronic overspeed device, eliminates or reduces the frequency of mechanical overspeed tests, minimizes damage to rotating turbine components caused by mechanical overspeed testing, and extends the equipment's service life.

[0047] In an optional implementation, the oil inlet is equipped with a first pressure switch 9, a second pressure switch 10, a third pressure switch 11, and corresponding pressure gauges and primary valves. In the event of an emergency oil pressure release, the main valve activates, and the unit trips; the first pressure switch 9, the second pressure switch 10, the third pressure switch 11, and the pressure transmitter issue a low pressure alarm. The three pressure switches prevent false tripping caused by the failure of one.

[0048] In an optional embodiment, the first speed measuring device 22 and the second speed measuring device 23 are respectively connected to three tachometers.

[0049] In an optional embodiment, the orifice diameter of the second orifice plate 20 is smaller than that of the first orifice plate 19. The second orifice plate 20 replenishes oil to the intermediate oil passage, while the first orifice plate 19 drains oil from the intermediate oil passage. Since the orifice diameter of the second orifice plate 20 is smaller than that of the first orifice plate 19, the pressure in the intermediate oil passage is lower than the pressure at the incoming oil end. When the first solenoid valve is energized, energizing the second solenoid valve determines whether the second solenoid valve is functioning correctly based on whether the oil pressure in the first oil passage rises to the same level as the incoming oil end. When the third solenoid valve is energized, energizing the fourth solenoid valve determines whether the fourth solenoid valve is functioning correctly based on whether the oil pressure in the second oil passage rises to the same level as the incoming oil end. If the orifice diameters of the first orifice plate 19 and the second orifice plate 20 are the same, and the pressure in the intermediate oil passage is the same as the pressure at the incoming oil end, when energizing the second and fourth solenoid valves while the first and third solenoid valves are energized, it is impossible to determine whether the second and fourth solenoid valves are functioning correctly.

[0050] In an optional embodiment, the return oil end is connected to the first solenoid valve 1, the third solenoid valve 3, and the first orifice plate 19 respectively; the incoming oil end is connected to the second solenoid valve 2, the fourth solenoid valve 4, and the second orifice plate 20 respectively.

[0051] Specifically, attached Figure 1 A dual electronic overspeed protection device for a turbine is provided, comprising a first speed measuring device 22, a second speed measuring device 23, three tachometers in each group, a first control module and a second control module integrated in an overspeed control cabinet 21, solenoid valves S1, S2, S3 and S4 receiving overspeed signals, a first orifice plate 19 for emergency oil return and a second orifice plate 20 for oil replenishment, local pressure gauges PI1 and PI2 for emergency oil, pressure transmitters PT1 and PT2 for emergency oil and pressure switches PS1, PS2 and PS3, and corresponding pressure gauge primary valves 12, 13, 14, 15, 16, 17 and 18. A first oil circuit, a second oil circuit, and a third oil circuit are connected in parallel at the oil inlet and oil outlet ends. Solenoid valves S1 and S2 are connected in series on the first oil circuit, and these solenoid valves S1 and S2 are connected to the first speed measuring device 22 via a first control module. Solenoid valves S3 and S4 are connected in series on the second oil circuit, and these solenoid valves S3 and S4 are connected to the first speed measuring device 22 via a second control module. The first and second control modules are integrated in the overspeed protection cabinet 21. A first orifice plate 19 and a second orifice plate 20 are connected in series on the third oil circuit. The oil circuits between solenoid valves S1 and S2, between solenoid valves S3 and S4, and between the first orifice plate 19 and the second orifice plate 20 are connected via an intermediate oil circuit. Pressure transmitter PT1 and local pressure gauge PI1 are connected to the intermediate oil circuit. Pressure transmitter PT2, local pressure gauge PI2, and pressure switches PS1, PS2, and PS3 are connected to the oil circuit at the emergency oil inlet end.

[0052] The six speed signals are grouped into sets of three. The three tachometers of the first speed measuring device 22 connect three speed signals to the first control module of the overspeed control cabinet 21. The speed signals are compared with a standard 3270 RPM. If the speed is greater than or equal to 3270 RPM, an overspeed action signal A1 is issued through the distributed control system (DCS), where A1 = 1. This drives solenoid valves S1 and S2 to depressurize the emergency oil, activate the main valve, and trip the unit (open). Otherwise, the signal is zero, and no action is taken. Similarly, the three tachometers of the second speed measuring device 23 connect three speed signals to the second control module of the overspeed control cabinet 21. The speed signals are compared with a standard 3270 RPM. If the speed is greater than or equal to 3270 RPM, an overspeed action signal A2 is issued through the distributed control system (DCS), where A2 = 1. This drives solenoid valves S3 and S4 to depressurize the emergency oil, activate the main valve, and trip the unit (open). Otherwise, the signal is zero, and no action is taken. During this period, pressure transmitters PT1 and PT2 and pressure switches PS1, PS2, and PS3 issue low pressure alarms. The device of this invention can realize online testing of the electric overspeed protection device, and can sequentially conduct online testing on four solenoid valves of two sets of devices to ensure the reliability and effectiveness of the overspeed protection device; and can quickly identify the equipment fault point by detecting pressure changes, low pressure and high pressure alarms through the pressure transmitter PT1.

[0053] Use such as Figure 1 When using the dual electronic overspeed protection device for the turbine shown, the following steps are included:

[0054] Step 1: Confirm that there are no alarm messages from pressure transmitters PT1 and PT2 and pressure switches PS1, PS2 and PS3; the readings of transmitter PT1 and local pressure gauge PI1 are consistent, indicating that the instruments are normal; the readings of transmitter PT2 and local pressure gauge PI2 are consistent, indicating that the instruments are normal; and there are no fault alarms from solenoid valves S1, S2, S3 and S4.

[0055] Step 2: The emergency oil supply line fills the emergency oil system through the first orifice plate 19 and the second orifice plate 20, and the pressure transmitters PT1, PT2 and pressure switches PS1, PS2 and PS3 exhaust the air through their own three-way valves.

[0056] Step 3: Check and confirm that the pressure of transmitters PT1 and PT2 is normal, and that the value displayed on PT1 is lower than that on PT2.

[0057] Step 4: Activate the six speed signals, overspeed control cabinet 21, and overspeed protection device. When the first set of speed signals exceeds the speed limit, the overspeed control cabinet 21 outputs a signal to energize solenoid valves S1 and S2. Solenoid valves S1 and S2 simultaneously activate, connecting the emergency oil return line, actuating the main valve, and tripping the unit. Simultaneously, low emergency oil pressure triggers low emergency oil pressure trip alarms from unit transmitters PT1 and PT2, and pressure switches PS1, PS2, and PS3. Similarly, when the second set of speed signals exceeds the speed limit, the overspeed control cabinet 21 outputs a signal to energize solenoid valves S3 and S4. Solenoid valves S3 and S4 simultaneously activate, connecting the emergency oil return line, actuating the main valve, and tripping the unit. Simultaneously, low emergency oil pressure triggers low emergency oil pressure trip alarms from unit transmitters PT1 and PT2, and pressure switches PS1, PS2, and PS3. (See...) Figure 2 Overspeed protection control logic.

[0058] Step 5: When the equipment is working normally, quickly identify the fault point using the pressure transmitter PT1. If the PT1 value is lower than the low alarm value, a low pressure alarm will be issued, indicating a fault in solenoid valves S1 and S3; if the PT1 value is higher than the high alarm value, a high pressure alarm will be issued, indicating a fault in solenoid valves S2 and S4.

[0059] Step Six: Online Testing of the Overspeed Protection Device. Simulate an abnormal speed signal using the overspeed protection device. The overspeed protection activates, energizing solenoid valve S3, causing the transmitter PT1 value to decrease and triggering a low alarm. Then, energizing solenoid valve S4 causes the transmitter PT1 value to increase, triggering a high alarm. The first overspeed device is functioning correctly. Next, simulate an abnormal speed signal using the overspeed protection device. The overspeed protection activates, energizing solenoid valve S3, causing the transmitter PT1 value to decrease and triggering a low alarm. Then, energizing solenoid valve S4 causes the transmitter PT1 value to increase, triggering a high alarm. The second overspeed device is functioning correctly. See [link to relevant documentation]. Figure 3 The logic diagram for the dual-electronic overspeed online test is shown. Online testing allows for the early detection of module or solenoid valve malfunctions, improving the reliability of the electronic overspeed device.

[0060] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0061] The overspeed protection device, method, and testing method provided in this invention, on the one hand, reduce the equipment failure rate and improve the reliability of the protection device by using two oil circuits with solenoid valves. By detecting oil pressure changes through a pressure transmitter installed between the two solenoid valves on the same oil circuit, the operating status of each component of the actuator can be quickly and effectively detected, allowing for timely detection of equipment faults and preventing equipment accidents. Furthermore, the device of this invention can perform online testing of the electrical overspeed protection device, sequentially testing four solenoid valves of two sets of devices online to ensure the reliability and effectiveness of the overspeed protection device. The pressure transmitter adds low and high pressure alarms, enabling rapid identification of equipment fault points. The device of this invention has high equipment reliability, eliminating or reducing the frequency of mechanical overspeed testing, minimizing damage to rotating turbine components caused by mechanical overspeed testing, and extending the service life of the equipment.

[0062] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0063] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0064] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. A method for overspeed protection using an overspeed protection device, characterized in that, The overspeed protection device includes: The first oil circuit, the second oil circuit, and the third oil circuit are connected in parallel at the oil inlet and oil outlet ends; A first solenoid valve and a second solenoid valve are connected in series in the first oil circuit; A third solenoid valve and a fourth solenoid valve are connected in series in the second oil circuit; The third oil line is provided with a first orifice plate and a second orifice plate connected in series. The first solenoid valve and the second solenoid valve are connected to the first speed measuring device through the first control module; The third solenoid valve and the fourth solenoid valve are connected to the second speed measuring device through the second control module; wherein, the oil circuit between the first solenoid valve and the second solenoid valve, the oil circuit between the third solenoid valve and the fourth solenoid valve, and the oil circuit between the first orifice plate and the second orifice plate are connected through an intermediate oil circuit; The aperture of the second orifice plate is smaller than that of the first orifice plate; The method includes: The first speed measuring device connects the speed signal to the first control module, outputs an overspeed action signal, drives the first solenoid valve and the second solenoid valve on the first oil circuit to open, and releases the emergency oil at the incoming oil end through the first oil circuit to the return oil end; The second speed measuring device connects the speed signal to the second control module, outputs an overspeed action signal, drives the third solenoid valve and the fourth solenoid valve on the second oil circuit to open, and releases the emergency oil at the incoming oil end through the second oil circuit to the return oil end; When the first solenoid valve is energized, when the second solenoid valve is energized, the second solenoid valve is judged to be normal based on whether the oil pressure in the first oil circuit rises to the same level as the oil inlet. When the third solenoid valve is energized, when the fourth solenoid valve is energized, the fourth solenoid valve is judged to be normal based on whether the oil pressure in the second oil circuit rises to the same level as the oil inlet.

2. The overspeed protection method as described in claim 1, characterized in that, A first local pressure gauge and a first pressure transmitter are installed on the intermediate oil line.

3. The overspeed protection method as described in claim 1 or 2, characterized in that, The oil inlet is equipped with a second local pressure gauge and a second pressure transmitter.

4. The overspeed protection method as described in claim 3, characterized in that, The oil inlet is equipped with a first pressure switch, a second pressure switch, and a third pressure switch.

5. The overspeed protection method as described in claim 1, characterized in that, The first speed measuring device and the second speed measuring device are integrated in the overspeed control box; the first speed measuring device and the second speed measuring device are respectively connected to three tachometers.

6. The overspeed protection method as described in claim 1, characterized in that, The return oil end is connected to the first solenoid valve, the third solenoid valve, and the first orifice plate, respectively; the incoming oil end is connected to the second solenoid valve, the fourth solenoid valve, and the second orifice plate, respectively.

7. The overspeed protection method as described in claim 1, characterized in that, During the period when the accident oil is depressurized through the first oil circuit to the return oil end, the first pressure transmitter connected to the intermediate oil circuit and the second pressure transmitter connected to the oil inlet end issue a low pressure alarm. During the period when the accident oil is depressurized through the second oil circuit to the return oil end, the first pressure transmitter connected to the intermediate oil circuit and the second pressure transmitter connected to the incoming oil end issue a low pressure alarm.

8. A method for testing the overspeed protection method using an overspeed protection device as described in any one of claims 1 to 7, characterized in that, include: The simulated speed signal is abnormally transmitted to the first solenoid valve. The first solenoid valve is energized and opened. The value of the first transmitter set in the intermediate oil circuit decreases and a low pressure alarm is issued. The first solenoid valve is normal. The simulated speed signal is abnormally transmitted to the second solenoid valve. The second solenoid valve is energized and opens. The value of the first transmitter increases and issues a high pressure alarm. The second solenoid valve is normal. The simulated speed signal is abnormally transmitted to the third solenoid valve, the third solenoid valve is energized and opened, the value of the first transmitter decreases and a low pressure alarm is issued, and the third solenoid valve is normal. The simulated speed signal is abnormally transmitted to the fourth solenoid valve, which is then energized and opened. The value of the first transmitter increases, triggering a high pressure alarm. The fourth solenoid valve is now functioning normally.

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