A main steam valve oil motor control system and control method

Abstract

The present invention discloses a main steam valve oil motor control system and control method. The control system includes an oil motor device, including a cylinder, a piston rod, and a main steam valve. The piston rod is movably disposed in the cylinder and connected to the main steam valve; an emergency shutdown protection device, including a pressure oil pipeline, three protection solenoid valves, three logic valves, and an oil return pipeline. The first port of each protection solenoid valve is connected to the pressure oil pipeline, the second ports of any two protection solenoid valves are connected to the first port and second port of the same logic valve in a one-to-one correspondence, the third ports of the three logic valves are connected to an unloading valve, the oil return pipeline is connected to the first port of the unloading valve, the second port of the unloading valve is connected to the lower chamber of the oil cylinder, and the third port of each protection solenoid valve is connected to the oil return pipeline; and a normal operation protection device, including a first solenoid valve, the pressure oil pipeline being connected to the lower chamber of the oil cylinder via the first solenoid valve. This application can improve the operational reliability of the main steam valve oil motor.

Description

Technical Field

[0001] The present invention relates to the field of steam turbine protection technology, and more specifically, to a main steam valve oil motor control system. In addition, the present invention also relates to a control method applied to the main steam valve oil motor control system. Background Art

[0002] A steam turbine is a rotary steam-powered device. The main steam valve oil motor is the main component of the turbine hydraulic protection system. It can quickly adjust the main steam valve steam inlet in the event of a turbine accident to adjust the turbine speed or load, and open the main steam valve in the normal state of the turbine.

[0003] Currently, the main steam valve oil motor is controlled by a solenoid valve and an unloading valve. Once the solenoid valve is energized, it controls the unloading valve to establish a restricted oil pressure, allowing the oil motor to operate normally and control the main steam valve to open. If the turbine requires emergency shutdown, the solenoid valve controls the unloading valve to remove the restricted oil pressure, allowing the oil motor to quickly close the main steam valve. However, if the solenoid valve loses power or a circuit fault occurs, the main steam valve cannot be quickly closed or opened normally, resulting in poor reliability of the main steam valve oil motor, which in turn affects the safe operation of the turbine.

[0004] In summary, how to provide a main steam valve oil motor control system with high operational reliability, which can ensure the rapid closing and normal opening of the main steam valve, is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a main steam valve oil motor control system, which has high operational reliability and can ensure that the main steam valve is quickly closed and normally opened.

[0006] Another object of the present invention is to provide a control method applied to the above-mentioned main steam valve oil motor control system.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A main steam valve oil motor control system, comprising:

[0009] The oil motor device comprises an oil cylinder, a piston rod and a main steam valve, wherein the piston rod is movably arranged in the oil cylinder and connected to the main steam valve;

[0010] Emergency stop protection device, including:

[0011] A pressure oil pipeline, three protection solenoid valves and three logic valves, wherein the first port of each protection solenoid valve is connected to the pressure oil pipeline, the second ports of any two protection solenoid valves are connected to the first port and the second port of the same logic valve in a one-to-one correspondence, and the third ports of the three logic valves are connected to the unloading valve;

[0012] an oil return pipeline connected to the first port of the unloading valve, the second port of the unloading valve is connected to the lower chamber of the oil cylinder, and the third port of each of the protection solenoid valves is connected to the oil return pipeline;

[0013] The normal operation protection device comprises a first solenoid valve, and the pressure oil pipeline is connected to the lower chamber of the oil cylinder through the first solenoid valve.

[0014] Preferably, the first solenoid valve is a two-position four-way solenoid valve, and the pressure oil pipeline is connected to the lower chamber of the oil cylinder through the first port and the second port of the first solenoid valve; and the lower chamber of the oil cylinder is connected to the return oil pipeline through the third port and the fourth port of the first solenoid valve.

[0015] Preferably, the normal operation protection device also includes a second solenoid valve, the lower chamber of the oil cylinder is connected to the return oil pipeline through the first port and the second port of the second solenoid valve, and a first throttling hole is provided on the connecting pipeline between the lower chamber of the oil cylinder and the second solenoid valve, and a second throttling hole is provided on the connecting pipeline between the second solenoid valve and the return oil pipeline, near the second port of the second solenoid valve.

[0016] Preferably, the first solenoid valve and the second solenoid valve are arranged in parallel.

[0017] Preferably, a manual valve is provided between the lower chamber of the oil cylinder and the oil return pipeline, and the manual valve is arranged in parallel with the second solenoid valve.

[0018] Preferably, a pressure switch is provided on the connecting pipeline between the protection solenoid valve and the logic valve.

[0019] Preferably, it further comprises a control device, wherein the control device is signal-connected to the protection solenoid valve, the first solenoid valve, the second solenoid valve and the pressure switch.

[0020] Preferably, the emergency shutdown protection device further includes a safety oil pipeline, and the safety oil pipeline is connected to the unloading valve.

[0021] A main steam valve oil motor control method is applied to any of the above main steam valve oil motor control systems, specifically comprising the following steps:

[0022] Control the main steam valve to open normally, control any two protection solenoid valves to be energized, and control the first and second ports of the protection solenoid valves to be connected. The pressure oil flows into the unloading valve through the protection solenoid valve and the logic valve, so that the first and second ports of the unloading valve are isolated. The pressure oil flows into the lower chamber of the oil cylinder through the first solenoid valve, and the piston rod moves upward until the main steam valve is fully opened;

[0023] Control the main steam valve to close quickly, control any two protection solenoid valves to lose power, and control the connection of the second port and the third port of the protection solenoid valve. The pressure oil in the unloading valve flows into the return oil pipeline through the logic valve and the protection solenoid valve, so that the first port and the second port of the unloading valve are connected.

[0024] When using the main steam valve oil motor control system provided by the present application, when the main steam valve needs to be opened normally, any two protection solenoid valves are energized, the first port and the second port of the protection solenoid valve are connected, and the pressure oil in the pressure oil pipeline flows into the unloading valve through the protection solenoid valve and the logic valve, the valve core of the unloading valve is pressurized, the first port and the second port of the unloading valve are isolated, the pressure oil in the pressure oil pipeline flows into the lower chamber of the oil cylinder through the first solenoid valve, the piston rod drives the main steam valve to move upward, the main steam valve gradually opens until it is fully opened, and the steam turbine is started; when the main steam valve needs to be closed quickly, any two protection solenoid valves are de-energized, the second port and the third port of the protection solenoid valve are connected, the pressure oil in the unloading valve flows into the return oil pipeline through the logic valve and the protection solenoid valve, the valve core of the unloading valve is pressurized gradually, the first port and the second port of the unloading valve are connected, the pressure oil in the lower chamber of the oil cylinder flows into the return oil pipeline through the unloading valve, the piston rod drives the main steam valve to move downward, the main steam valve is quickly closed, and the steam turbine is shut down.

[0025] Therefore, when the steam turbine needs to be shut down, any two of the three protection solenoid valves lose power at the same time, and the pressure oil in the unloading valve can be discharged, so that the first port and the second port of the unloading valve are connected, thereby quickly closing the main steam valve; in addition, when the steam turbine needs to be started, any two of the three protection solenoid valves are energized at the same time, and the pressure oil can also enter the unloading valve through the protection solenoid valve and the logic valve, so that the first port and the second port of the unloading valve are isolated, thereby opening the main steam valve. Therefore, the protection solenoid valve of the present application adopts a three-out-two form to control the rapid closing of the main steam valve and the normal opening of the main steam valve, which can improve the operating reliability of the main steam valve oil motor, thereby ensuring the safe operation of the steam turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0027] Figure 1 This is a structural schematic diagram of a main steam valve oil motor control system provided by the present invention.

[0028] In the picture:

[0029] 1 is the oil cylinder, 2 is the piston rod, 3 is the pressure oil pipeline, 4 is the return oil pipeline, 5 is the safety oil pipeline, 6 is the protection solenoid valve, 7 is the logic valve, 8 is the unloading valve, 9 is the first solenoid valve, 10 is the second solenoid valve, 11 is the manual valve, 12 is the pressure switch, 13 is the first throttle hole, and 14 is the second throttle hole;

[0030] 61 is the first port of the protection solenoid valve, 62 is the second port of the protection solenoid valve, 63 is the third port of the protection solenoid valve, 64 is the first protection solenoid valve, 65 is the second protection solenoid valve, and 66 is the third protection solenoid valve;

[0031] 71 is the first port of the logic valve, 72 is the second port of the logic valve, 73 is the third port of the logic valve, 74 is the first logic valve, 75 is the second logic valve, and 76 is the third logic valve;

[0032] 81 is the first port of the unloading valve, and 82 is the second port of the unloading valve;

[0033] 91 is the first port of the first solenoid valve, 92 is the second port of the first solenoid valve, 93 is the third port of the first solenoid valve, and 94 is the fourth port of the first solenoid valve;

[0034] 101 is a first port of the second electromagnetic valve, and 102 is a second port of the second electromagnetic valve. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] The core of the present invention is to provide a main steam valve oil motor control system, which has high operational reliability and can ensure the rapid closing and normal opening of the main steam valve.

[0037] Another core of the present invention is to provide a control method including the above-mentioned control method applied to the above-mentioned main steam valve oil motor control system.

[0038] It should be noted that relational terms such as first, second, third, fourth, etc. described below are merely used to distinguish one entity from other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0039] Please refer to Figure 1 The present application provides a main steam valve oil motor control system, including an oil motor device, an emergency shutdown protection device and a normal operation protection device.

[0040] The oil motor device is used to control the steam intake of the steam turbine. The oil motor device includes a cylinder 1, a piston rod 2 and a main steam valve. The piston rod 2 is movably arranged in the cylinder 1, and the piston rod 2 can move up and down along the inner wall of the cylinder 1. The bottom end of the piston rod 2 is connected to the main steam valve to drive the main steam valve to move up and down, thereby realizing the opening and closing of the main steam valve.

[0041] The emergency shutdown protection pipeline includes a pressure oil pipeline 3, a return oil pipeline 4, three protection solenoid valves 6 and three logic valves 7; the first port 61 of each protection solenoid valve is connected to the pressure oil pipeline 3, and the second port 62 of any two protection solenoid valves 6 is connected to the first port 71 and the second port 72 of the same logic valve 7 in a one-to-one correspondence; the third port 73 of the three logic valves 7 is connected to the unloading valve 8.

[0042] It should be noted that the three protection solenoid valves 6 are respectively the first protection solenoid valve 64, the second protection solenoid valve 65 and the third protection solenoid valve 66, and the three logic valves 7 are respectively the first logic valve 74, the second logic valve 75 and the third logic valve 76; the first port of the first logic valve 74 is connected to the second port of the first protection solenoid valve 64, the second port of the first logic valve 74 is connected to the second port of the second protection solenoid valve 65, the first port of the second logic valve 75 is connected to the second port of the second protection solenoid valve 65, the second port of the second logic valve 75 is connected to the second port of the third protection solenoid valve 66, the first port of the third logic valve 76 is connected to the second port of the first protection solenoid valve 64, the second port of the third logic valve 76 is connected to the second port of the third protection solenoid valve 66, and the third ports of the first logic valve 74, the second logic valve 75 and the third logic valve 76 are all connected to the unloading valve 8.

[0043] In addition, the valve core of the unloading valve 8 can move up and down along the inner wall of the unloading valve 8, the third port 73 of the logic valve is connected to the upper chamber of the unloading valve 8, and the first port 81 and the second port 82 of the unloading valve are located in the lower chamber.

[0044] The oil return line 4 is connected to the first port 81 of the unloading valve, the second port 82 of the unloading valve is connected to the lower chamber of the oil cylinder 1 , and the third ports 63 of each protection solenoid valve are connected to the oil return line 4 .

[0045] The normal operation protection device includes a first solenoid valve 9 , and the pressure oil pipeline 3 is connected to the lower chamber of the oil cylinder 1 through the first solenoid valve 9 .

[0046] It should be noted that the logic valve 7 is used to control the flow direction of pressurized oil. When there is pressurized oil in the first port 71 of the logic valve, and / or when there is pressurized oil in the second port 72 of the logic valve, pressurized oil flows into the third port 73 of the logic valve; the first port 71 and the second port 72 of the logic valve are both connected to the return oil pipeline 4, and the third port 73 of the logic valve is connected to the return oil pipeline 4.

[0047] During use, when the main steam valve needs to be opened normally, any two protection solenoid valves 6 are energized, connecting the first port 61 and the second port 62 of the protection solenoid valve, and the pressure oil in the pressure oil pipeline 3 flows into the unloading valve 8 through the protection solenoid valve 6 and the logic valve 7. The valve core of the unloading valve 8 is pressurized, and the first port 81 and the second port 82 of the unloading valve are isolated. The pressure oil in the pressure oil pipeline 3 flows into the lower chamber of the oil cylinder 1 through the first solenoid valve 9, and the piston rod 2 drives the main steam valve to move upward, and the main steam valve gradually opens until it is fully opened, thereby the steam The turbine is started; when the main steam valve needs to be closed quickly, any two protection solenoid valves 6 lose power, and the second port 62 and the third port 63 of the protection solenoid valve are connected. The pressure oil in the unloading valve 8 flows into the return oil pipeline 4 through the logic valve 7 and the protection solenoid valve 6. The pressure on the valve core of the unloading valve 8 gradually decreases, and the first port 81 and the second port 82 of the unloading valve are connected. The pressure oil in the lower chamber of the cylinder 1 flows into the return oil pipeline 4 through the unloading valve 8, and the piston rod 2 drives the main steam valve to move downward, and the main steam valve closes quickly, thereby shutting down the turbine.

[0048] Therefore, when the steam turbine needs to be shut down, any two of the three protective solenoid valves 6 lose power at the same time, and the pressure oil in the unloading valve 8 can be unloaded, so that the first port 81 and the second port of the unloading valve are connected, thereby quickly closing the main steam valve; in addition, when the steam turbine needs to be started, any two of the three protective solenoid valves 6 are energized at the same time, and the pressure oil can also enter the unloading valve 8 through the protective solenoid valve 6 and the logic valve 7, so that the first port 81 and the second port 82 of the unloading valve are isolated, thereby opening the main steam valve. Therefore, the protective solenoid valve 6 of the present application adopts a three-out-two method to control the rapid closing of the main steam valve and the normal opening of the main steam valve, which can improve the reliability of the main steam valve oil motor operation, thereby ensuring the safe operation of the steam turbine.

[0049] Optionally, a servo valve is provided between the lower chamber of the oil motor and the pressure oil pipeline 3 and the return oil pipeline 4. When the oil motor is working normally, that is, the oil motor controls the main steam valve to open or close normally, the normal operation of the oil motor is controlled by the servo valve.

[0050] It should be noted that the main steam valve needs to be rigorously tested. The rigorous test requires the main steam valve to be completely closed to detect whether the main steam valve is rigorously designed, that is, to check whether the main steam valve has any leakage.

[0051] On the basis of the above embodiment, the first solenoid valve 9 is a two-position four-way solenoid valve, and the pressure oil pipeline 3 is connected to the lower chamber of the cylinder 1 through the first port 91 and the second port 92 of the first solenoid valve; and the lower chamber of the cylinder 1 is connected to the return oil pipeline 4 through the third port 93 and the fourth port 94 of the first solenoid valve.

[0052] Specifically, the first solenoid valve 9 adopts a two-position four-way solenoid valve, one of which is a first port 91 and a second port 92, and the other is a third port 93 and a fourth port 94. The first port 91 and the second port 92 of the first solenoid valve connect the pressure oil pipeline 3 with the lower chamber of the oil cylinder 1, and the third port 93 and the fourth port 94 of the first solenoid valve connect the return oil pipeline 4 with the lower chamber of the oil cylinder 1. Therefore, when the main steam valve needs to be opened, the first solenoid valve 9 is energized, the first port 91 and the second port 92 of the first solenoid valve are connected, and the pressure oil flows into the lower chamber of the oil cylinder 1 through the first solenoid valve 9; when a rigorous test is required, the first solenoid valve 9 is energized, the third port 93 and the fourth port 94 of the first solenoid valve are connected, and the pressure oil in the lower chamber of the oil cylinder 1 flows into the return oil pipeline 4 through the first solenoid valve 9, and the piston rod 2 drives the main steam valve to gradually move upward, so that the main steam valve is gradually closed.

[0053] Optionally, the type of the first solenoid valve 9 of the present application is not unique and can be selected according to actual needs to meet the goal of connecting the first solenoid valve 9 to the return oil pipeline 4 and the pressure oil pipeline 3 respectively.

[0054] It should be noted that since the main steam valve is often open, the main steam valve needs to be tested for activity to prevent it from getting stuck and tightening, which would affect the safe operation reliability of the main steam valve oil motor.

[0055] On the basis of the above embodiment, the normal operation protection device also includes a second solenoid valve 10, and the lower chamber of the oil cylinder 1 is connected to the return oil pipeline 4 through the first port 101 and the second port 102 of the second solenoid valve, and a first throttling hole 13 is provided on the connecting pipeline between the lower chamber of the oil cylinder 1 and the second solenoid valve 10, and a second throttling hole 14 is provided on the connecting pipeline between the second solenoid valve 10 and the return oil pipeline 4, near the second port 102 of the second solenoid valve.

[0056] It should be noted that the function of the throttle hole is to reduce the aperture at the appropriate position of the pipeline, thereby generating a static pressure difference on the upstream and downstream sides of the pipeline. The flow velocity of the upstream liquid in the throttle hole area increases, and the liquid pressure decreases greatly as the flow velocity increases. However, the liquid flows into the expanded downstream area, the velocity decreases, and the pressure increases, but the downstream pressure cannot return to the upstream pressure, thereby playing a throttling role.

[0057] When an active test is required, the degree of closing of the main steam valve corresponds to the downward stroke of the piston rod 2. The apertures of the first throttle hole 13 and the second throttle hole 14 are adjusted according to the degree of closing of the main steam valve. The second solenoid valve 10 is energized, connecting the first port 101 and the second port 102 of the second solenoid valve. The pressure oil in the lower chamber of the oil cylinder 1 flows into the return oil pipeline 4 through the solenoid valve. The piston rod 2 drives the main steam valve to move gradually upward, and the opening of the main steam valve decreases. Since the pressure oil decreases after throttling through the first throttle hole 13, that is, the pressure upstream of the second throttle hole 14 decreases, when the downstream pressure of the second throttle hole 14 is greater than the upstream pressure, the pressure oil stops flowing into the return oil pipeline 4. Therefore, even if the second solenoid valve 10 fails, it can prevent the pressure oil in the oil cylinder 1 from flowing back into the return oil pipeline 4, thereby ensuring that the main steam valve will not be completely closed.

[0058] On the basis of the above embodiment, the first solenoid valve 9 and the second solenoid valve 10 are arranged in parallel between the lower chamber of the cylinder 1 and the return oil pipeline 4. Therefore, when an activity test is required, the second solenoid valve 10 is energized, and the first port 101 and the second port 102 of the second solenoid valve are connected. The pressure oil in the cylinder 1 flows into the return oil pipeline 4 through the first solenoid valve 9, and the main steam valve gradually closes. To ensure that the main steam valve is not completely closed, the first solenoid valve 9 is energized for a certain time. The energization time needs to be set according to the degree of closing of the main steam valve. The third port 93 and the fourth port 94 of the first solenoid valve are connected. Part of the pressure oil in the upstream pipeline of the second solenoid valve 10 flows into the return oil pipeline 4 through the first solenoid valve 9, the pressure of the upstream pipeline is reduced, and the pressure of the downstream pipeline of the second solenoid valve 10 is greater than the pressure of the upstream pipeline. The pressure oil flowing out of the second port 102 of the second solenoid valve is reduced, thereby ensuring that the pressure oil in the cylinder 1 does not flow out completely, and further ensuring that the main steam valve is not completely closed.

[0059] On the basis of the above embodiment, a manual valve 11 is provided between the lower chamber of the oil cylinder 1 and the return oil pipeline 4, and the manual valve 11 is arranged in parallel with the second solenoid valve 10 for manual activity test, so as to facilitate the control of the downward movement stroke of the piston rod 2 and prevent the second solenoid valve 10 from losing power and causing the main steam valve to be completely closed.

[0060] On the basis of the above embodiment, a pressure switch 12 is provided on the connecting pipeline between the protection solenoid valve 6 and the logic valve 7. Therefore, the protection solenoid valve 6 can be detected online. If the adjacent protection solenoid valve 6 loses power temporarily, the pressure switch 12 can be used to determine whether the protection solenoid valve 6 is normal.

[0061] Based on the above embodiment, the main steam valve oil motor control system also includes a control device, the control device signal is connected to the protection solenoid valve 6, the first solenoid valve 9, the second solenoid valve 10 and the pressure switch 12, so as to facilitate remote operation of the main steam valve oil motor control system.

[0062] On the basis of the above embodiment, the emergency shutdown protection device also includes a safety oil pipeline 5, which is connected to the unloading valve 8. Specifically, the safety oil pipeline 5 is used to transport safety oil to the upper chamber of the unloading valve 8. This oil does not have fluidity under normal circumstances, so as to isolate the first port 81 and the second port 82 of the unloading valve, thereby further ensuring that the main steam valve is opened normally.

[0063] In addition to the above-mentioned main steam valve oil motor control system, the present invention also provides a main steam valve oil motor control method. The main steam valve oil motor control method is applied to the above-mentioned main steam valve oil motor control system and specifically includes the following steps:

[0064] Control the main steam valve to open normally, control any two protection solenoid valves to be energized, and control the first and second ports of the protection solenoid valves to be connected. The pressure oil in the pressure oil pipeline flows into the unloading valve through the protection solenoid valve and the logic valve, so that the first and second ports of the unloading valve are isolated. The pressure oil in the pressure oil pipeline flows into the lower chamber of the oil cylinder through the first solenoid valve, and the piston rod drives the main steam valve to move upward until the main steam valve is fully opened;

[0065] Control the main steam valve to close quickly, control any two protection solenoid valves to lose power, and control the second and third ports of the protection solenoid valve to be connected. The pressure oil in the unloading valve flows into the return oil pipeline through the logic valve and the protection solenoid valve, so that the first and second ports of the unloading valve are connected, and the pressure oil in the lower chamber of the cylinder flows into the return oil pipeline through the unloading valve. The piston rod drives the main steam valve to move downward, and the main steam valve closes quickly.

[0066] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0067] The above describes in detail the main valve oil motor control system and control method provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to facilitate understanding of the method and core concept of the present invention. It should be noted that those skilled in the art may make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A main valve oil motor control system, characterized in that: include: The oil motor device comprises an oil cylinder, a piston rod and a main steam valve, wherein the piston rod is movably arranged in the oil cylinder and connected to the main steam valve; Emergency stop protection device, including: A pressure oil pipeline, three protection solenoid valves and three logic valves, wherein the first port of each protection solenoid valve is connected to the pressure oil pipeline, the second ports of any two protection solenoid valves are connected to the first port and the second port of the same logic valve in a one-to-one correspondence, and the third ports of the three logic valves are connected to the unloading valve; an oil return pipeline connected to the first port of the unloading valve, the second port of the unloading valve is connected to the lower chamber of the oil cylinder, and the third port of each of the protection solenoid valves is connected to the oil return pipeline; The normal operation protection device includes a first solenoid valve, and the pressure oil pipeline is connected to the lower chamber of the oil cylinder through the first solenoid valve; The first solenoid valve is a two-position four-way solenoid valve, the pressure oil pipeline is connected to the lower chamber of the oil cylinder through the first port and the second port of the first solenoid valve; and the lower chamber of the oil cylinder is connected to the return oil pipeline through the third port and the fourth port of the first solenoid valve; The normal operation protection device also includes a second solenoid valve, the lower chamber of the oil cylinder is connected to the return oil pipeline through the first port and the second port of the second solenoid valve, and a first throttling hole is provided on the connecting pipeline between the lower chamber of the oil cylinder and the second solenoid valve, and a second throttling hole is provided on the connecting pipeline between the second solenoid valve and the return oil pipeline, near the second port of the second solenoid valve.

2. The main valve oil motor control system according to claim 1, characterized in that: The first solenoid valve and the second solenoid valve are arranged in parallel.

3. The main valve oil motor control system according to claim 2, characterized in that: A manual valve is provided between the lower chamber of the oil cylinder and the oil return pipeline, and the manual valve is arranged in parallel with the second solenoid valve.

4. The main valve oil motor control system according to any one of claims 1 to 3, characterized in that: A pressure switch is provided on the connecting pipeline between the protection solenoid valve and the logic valve.

5. The main valve oil motor control system according to claim 4, characterized in that: It also includes a control device, which is signal-connected to the protection solenoid valve, the first solenoid valve, the second solenoid valve and the pressure switch.

6. The main valve oil motor control system according to any one of claims 1 to 3, characterized in that: The emergency shutdown protection device further includes a safety oil pipeline, which is connected to the unloading valve.

7. A main valve oil motor control method, characterized in that: The main valve oil motor control method is applied to the main valve oil motor control system according to any one of claims 1 to 6, and specifically comprises the following steps: Control the main steam valve to open normally, control any two protection solenoid valves to be energized, and control the first and second ports of the protection solenoid valves to be connected. The pressure oil flows into the unloading valve through the protection solenoid valve and the logic valve, so that the first and second ports of the unloading valve are isolated. The pressure oil flows into the lower chamber of the oil cylinder through the first solenoid valve, and the piston rod moves upward until the main steam valve is fully opened; Control the main steam valve to close quickly, control any two protection solenoid valves to lose power, and control the connection of the second port and the third port of the protection solenoid valve. The pressure oil in the unloading valve flows into the return oil pipeline through the logic valve and the protection solenoid valve, so that the first port and the second port of the unloading valve are connected.

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