Turbine interruption protection device capable of being overhauled on line

Abstract

The invention relates to the technical field of steam turbine interruption protection systems, and discloses a steam turbine interruption protection device capable of being overhauled online. A non-pressure oil return mother pipe; an overspeed protection oil pipeline; the oil mother pipe is intercepted and protected; the on-line overhaul isolation device is configured to selectively and physically isolate communication between the first electromagnetic valve group or the second electromagnetic valve group and the non-pressure oil return main pipe when on-line overhaul is needed, and the one-way valves are arranged on the first oil way and the third oil way; oil flow is prevented from flowing backwards into the pressure oil mother pipe; a valve element position sensor is integrated on the electromagnetic valve, a pressure monitoring unit comprises a precise throttling hole and a pressure measuring point, dual signal collection is carried out, the real working state of the electromagnetic valve can be monitored in real time, logical operation and interlocking analysis are carried out on a valve element position signal and an oil pressure signal, the fault type is clearly distinguished, and the fault type is accurately positioned.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of a turbine trip protection system, in particular to a turbine trip protection device capable of on-line maintenance. BACKGROUND

[0002] Turbine trip protection is a key system for ensuring the safe operation of a turbine. When the turbine is in an abnormal operating condition such as overspeed, excessive shaft vibration, low lubricating oil pressure, abnormal shaft displacement, etc., which may endanger the safety of equipment and personnel, the trip protection system will act quickly to close the main steam valve and the regulating valve, cut off the steam entering the turbine, and make the turbine emergency stop to avoid equipment damage and accident expansion, and ensure the stability and safety of the entire power generation system.

[0003] Currently, the high-pressure fire-resistant oil regulating system used in the existing turbine industry provides regulation and protection for the normal operation of the turbine. The emergency trip device is a protection device for the high-pressure fire-resistant oil system to protect the normal operation and emergency stop of the turbine. The emergency trip device has two protection functions. One is overspeed protection (OPC), which acts when the turbine speed reaches the overspeed protection set value, closes the high-pressure regulating valve, cuts off the steam flow, and reduces the turbine speed, but cannot stop the turbine. The second is emergency trip (AST), which acts when the turbine is running and the stop protection set value is triggered, cuts off the main steam valve, closes all steam inlet valves such as the high-pressure regulating valve, and immediately stops. Since the AST solenoid valve is designed to be in a long-term live working state, it can realize online testing of whether the solenoid valve is faulty. The OPC solenoid valve is designed redundantly. Since the AST solenoid valve is in a long-term live working state, the fault rate of the solenoid valve is high due to unstable power supply voltage. The emergency trip device uses modular high integration, and the fault point cannot be accurately determined, so it does not have an on-line maintenance function. SUMMARY

[0004] The present application aims to provide a turbine trip protection device capable of on-line maintenance, which solves the problem of high fault rate of the solenoid valve due to unstable power supply voltage and long-term live working state, and the emergency trip device uses modular high integration, and the fault point cannot be accurately determined.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] A turbine trip protection device capable of on-line maintenance, comprising:

[0007] A high-pressure (HP) pressure oil main pipe;

[0008] A non-pressure oil return (DV) main pipe;

[0009] An OPC overspeed protection oil pipeline;

[0010] AST block protection oil pipe;

[0011] Dual-redundant AST valve group, comprising a first group of AST solenoid valves and a second group of AST solenoid valves;

[0012] ASP pressure monitoring unit: connected to the AST block protection oil pipe, used for monitoring the pressure state of the AST block protection oil and detecting valve group leakage;

[0013] OPC overspeed protection control oil circuit: connected to the OPC overspeed protection oil circuit, comprising at least two OPC solenoid valves (OPC1, OPC2) arranged in parallel;

[0014] Online maintenance isolation device: arranged on the second oil circuit and the fourth oil circuit, the online maintenance isolation device is configured to selectively physically isolate the communication between the first group of AST solenoid valves or the second group of AST solenoid valves and the DV pressureless return oil pipe when online maintenance is needed; wherein:

[0015] The inlet of the OPC solenoid valve is connected to the HP pressure oil pipe, and the outlet is connected to the OPC overspeed protection oil circuit. The high-pressure (HP) pressure oil pipe provides a high-pressure oil source, and the pressureless return oil (DV) pipe is used for oil return. The OPC overspeed protection oil circuit and the AST block protection oil pipe respectively undertake the oil pressure control tasks of overspeed protection and block protection. The dual-redundant AST valve group is provided with two groups of solenoid valves, which enhances the system reliability. The ASP pressure monitoring unit monitors the pressure state of the AST block protection oil and can detect valve group leakage. The OPC overspeed protection control oil circuit controls the pressure of the OPC overspeed protection oil through the parallel OPC solenoid valves. The online maintenance isolation device can physically isolate the communication between a group of AST solenoid valves and the pressureless return oil pipe when needed. The OPC solenoid valve inlet is connected to the high-pressure oil pipe, and the outlet is connected to the OPC overspeed protection oil circuit to realize oil pressure control. The check valve prevents oil from flowing back into the high-pressure oil pipe, ensuring the stability and safety of the system oil pressure. Through the above design, the device can realize the overspeed protection and block protection functions of the steam turbine. The dual-redundant AST valve group improves the system reliability and fault tolerance. The ASP pressure monitoring unit can detect valve group leakage in time, and the OPC overspeed protection control oil circuit ensures the safety of the steam turbine in overspeed. The online maintenance isolation device allows online maintenance of the AST solenoid valve group without affecting the normal operation of the steam turbine, reducing downtime and improving production efficiency.

[0016] The AST blocking protection oil pipe is at least led out from the first oil way upstream of the first group of AST electromagnetic valves and a one-way valve arranged on the first oil way and the third oil way to prevent oil from flowing back into the HP pressure oil main pipe. The on-line maintenance isolation device is provided with a first maintenance cut-off valve corresponding to the first group of AST electromagnetic valves on the second oil way and a second maintenance cut-off valve corresponding to the second group of AST electromagnetic valves on the fourth oil way. When a group of AST electromagnetic valves needs to be maintained, the corresponding maintenance cut-off valve is closed to cut off the communication between the group of electromagnetic valves and the pressureless return oil main pipe, thereby achieving physical isolation. The setting is simple and direct, the closing and opening functions of the cut-off valve are used to conveniently isolate and restore the AST electromagnetic valve group, facilitate on-line maintenance operation, and the cut-off valve has simple structure and high reliability.

[0017] Preferably, the on-line maintenance isolation device comprises a first maintenance cut-off valve corresponding to the first group of AST electromagnetic valves arranged on the second oil way and a second maintenance cut-off valve corresponding to the second group of AST electromagnetic valves arranged on the fourth oil way. The on-line maintenance isolation device is provided with a first maintenance electromagnetic valve corresponding to the first group of AST electromagnetic valves on the second oil way and a second maintenance electromagnetic valve corresponding to the second group of AST electromagnetic valves on the fourth oil way. By controlling the on-off of the electromagnetic valve, the selective isolation of the communication between a group of AST electromagnetic valves and the pressureless return oil main pipe can be realized. The electromagnetic valve can realize remote control and automatic operation, and can quickly and accurately isolate the corresponding AST electromagnetic valve group when on-line maintenance is needed, thereby improving the timeliness and convenience of maintenance and facilitating integration with the control system to realize intelligent management.

[0018] Preferably, the on-line maintenance isolation device comprises a first maintenance electromagnetic valve corresponding to the first group of AST electromagnetic valves arranged on the second oil way and a second maintenance electromagnetic valve corresponding to the second group of AST electromagnetic valves arranged on the fourth oil way. The ASP pressure monitoring unit is provided with a first precision throttle hole and a second precision throttle hole in the oil way upstream and downstream of the ASP pressure measurement point to stabilize the oil way pressure through the throttling effect. The ASP pressure gauge is connected to the ASP pressure measurement point to monitor the pressure of the point in real time. When the AST blocking protection oil main pipe or the valve group has an abnormal condition such as leakage, the pressure of the ASP pressure measurement point will change, and the pressure gauge can detect this change in time. Through real-time monitoring of the pressure of the ASP pressure measurement point, the leakage of the valve group in the AST blocking protection oil system can be found in time, thereby providing protection for the safe operation of the system, facilitating timely maintenance measures, and avoiding the expansion of faults.

[0019] Preferably, the ASP pressure monitoring unit comprises:

[0020] The system includes an ASP pressure measurement point, a first precision throttling orifice, a second precision throttling orifice, and an ASP pressure gauge. The first precision throttling orifice is located in the oil circuit upstream of the ASP pressure measurement point, and the second precision throttling orifice is located in the oil circuit downstream of the ASP pressure measurement point leading to the return oil. The ASP pressure gauge is connected to the ASP pressure measurement point for real-time pressure monitoring. One-way valves are provided: a first one-way valve and a second one-way valve. The first one-way valve is located in the first oil circuit at the inlet of the first AST solenoid valve group, and the second one-way valve is located in the third oil circuit at the inlet of the second AST solenoid valve group. Its function is to utilize the unidirectional conduction characteristic to prevent oil flow from the AST solenoid valve group to the HP pressure oil header in reverse, ensuring stable oil pressure in the high-pressure oil header, preventing backflow into the high-pressure oil header, and ensuring stable oil pressure in the high-pressure oil header. This avoids the impact of backflow on the high-pressure oil source, improving the safety and reliability of the system.

[0021] Preferably, the one-way valve includes:

[0022] A first check valve and a second check valve are provided. The first check valve is located on the first oil line at the inlet of the first group of AST solenoid valves and is used to prevent oil flow from the first group of AST solenoid valves to the HP pressure oil header in reverse. The second check valve is located on the third oil line at the inlet of the second group of AST solenoid valves and is used to prevent oil flow from the second group of AST solenoid valves to the HP pressure oil header in reverse. An OPC check valve is provided in the OPC overspeed protection control oil circuit, located on the OPC overspeed protection oil line. Its function is to prevent oil flow from flowing backward from the OPC overspeed protection oil line to the OPC solenoid valves and the unpressurized return oil header, ensuring stable oil pressure in the OPC overspeed protection oil line, ensuring that the oil pressure in the OPC overspeed protection oil line flows in the designed direction, preventing abnormal reverse flow of oil pressure from affecting the OPC solenoid valves and the unpressurized return oil header, and ensuring the normal operation of the OPC overspeed protection function.

[0023] Preferably, the OPC overspeed protection control oil circuit also includes an OPC check valve. The OPC check valve is installed on the OPC overspeed protection oil line and is used to prevent oil flow from flowing backwards from the OPC overspeed protection oil line to the OPC solenoid valve and the DV unpressurized return oil header. Pressure test points are installed on the oil lines near the inlet and outlet of the first and second AST solenoid valve groups. During the isolation and maintenance of the AST solenoid valve group, the sealing performance and on / off function of the solenoid valve can be determined by measuring the pressure at the pressure test points. During the isolation and maintenance, the performance of the solenoid valve can be conveniently tested, problems with the solenoid valve can be detected in a timely manner, ensuring that the solenoid valve can work normally after maintenance, improving maintenance quality and system reliability.

[0024] Preferably, the system also includes pressure test points, which are located on the oil lines near the inlet and outlet of the first and second AST solenoid valve groups. These test points are used to test the sealing performance and on / off function of the solenoid valves during isolation maintenance. The system employs a redundant design, ensuring that if a single AST solenoid valve fails, the other AST solenoid valve group can still operate normally, preventing pressure leakage of the AST shut-off protection oil and allowing the turbine to operate normally. When online maintenance of the first AST solenoid valve group is required, the first maintenance shut-off valve or the first maintenance solenoid valve is closed or isolated, causing the first solenoid valve group to cease operation. Simultaneously, the second AST solenoid valve group is confirmed to be functioning normally via the ASP pressure monitoring unit or pressure test points. Similarly, when maintaining the second AST solenoid valve group, the second maintenance shut-off valve or the second maintenance solenoid valve is closed or isolated, confirming the normal operation of the first AST solenoid valve group. This redundancy design improves system reliability, ensuring the turbine can still operate normally even if a single AST solenoid valve fails. The online maintenance function allows for maintenance of the AST solenoid valve group without affecting the normal operation of the turbine, reducing downtime and improving production efficiency and equipment availability.

[0025] Preferably, the system is configured as follows:

[0026] When a single AST solenoid valve fails, the system redundancy design ensures that the AST shutdown protection oil does not leak and the turbine operates normally. The AST solenoid valve includes any one of AST1, AST2, AST3, and AST4.

[0027] When the first group of AST solenoid valves needs to be inspected online, the first inspection shut-off valve or the first inspection solenoid valve is closed or isolated, and the first group of solenoid valves is isolated to stop working. At the same time, the second group of AST solenoid valves is confirmed to be working normally through the ASP pressure monitoring unit or pressure test point, and the turbine does not need to be shut down.

[0028] When online maintenance of the second group of AST solenoid valves is required, the second maintenance shut-off valve or the second maintenance solenoid valve is closed or isolated, isolating the second group of solenoid valves to disable their operation. Simultaneously, the first group of AST solenoid valves is confirmed to be functioning normally via the ASP pressure monitoring unit or pressure test point. The turbine does not need to be shut down. The OPC solenoid valves employ a parallel redundant design, including OPC1 and OPC2, with an OPC pressure gauge installed on the outlet manifold. This parallel design ensures that if one OPC solenoid valve fails, the other continues to operate normally, guaranteeing the implementation of the OPC overspeed protection function. The OPC pressure gauge monitors the status of the OPC overspeed protection oil. The parallel redundant design improves the reliability of the OPC overspeed protection control oil circuit. The OPC pressure gauge can monitor the pressure status of the OPC overspeed protection oil in real time, facilitating timely detection of abnormalities in the OPC overspeed protection system and ensuring timely protection of the turbine during overspeed.

[0029] Preferably, the OPC solenoid valve adopts a parallel redundant design, the OPC solenoid valve includes OPC1 and OPC2, and an OPC pressure gauge is installed on the outlet manifold of the OPC solenoid valve. The OPC pressure gauge is used to monitor the status of the OPC overspeed protection oil.

[0030] Preferably, the solenoid valves in the first and second AST solenoid valve groups adopt a modular design, facilitating overall online replacement. This modular design combines multiple solenoid valves into a single module. During maintenance or replacement, the entire module can be operated as a whole, enabling online replacement of the entire solenoid valve group and reducing maintenance time and workload. In case of a fault, the faulty module can be quickly replaced, shortening downtime, improving equipment maintenance efficiency and availability, and also benefiting equipment maintenance and management.

[0031] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0032] 1. This invention integrates a valve core position sensor into the AST solenoid valve and combines it with an ASP pressure monitoring unit containing a precision throttle orifice and pressure measurement points for dual signal acquisition. This enables real-time monitoring of the solenoid valve's actual operating status. By performing logical operations and interlocking analysis on the valve core position signal and ASP oil pressure signal, it clearly distinguishes and accurately locates the fault type, such as AST solenoid valve coil de-energization fault, valve core jamming fault, or related two-way logic cartridge valve jamming fault. This completely changes the ambiguous state of existing technologies that can only report "device fault" but cannot locate the specific fault point, greatly improving the accuracy and efficiency of fault diagnosis.

[0033] 2. This invention innovatively designs an online isolation maintenance device, including an oil inlet shut-off valve located in the oil inlet pipeline of each AST valve group and a valve core mechanical limiting mechanism acting on the two-way logic cartridge valve. When a fault is diagnosed in a single AST solenoid valve, the valve core limiting mechanism corresponding to that valve group can be operated under normal turbine operation to lock the valve core of the two-way cartridge valve in the working position, thereby preventing accidental oil leakage and shutdown during maintenance. This process requires no shutdown, avoiding the huge economic losses and efficiency reduction caused by the previous need to shut down for maintenance due to AST solenoid valve faults, and significantly improving the continuity and availability of unit operation. Attached Figure Description

[0034] Figure 1 This is a complete diagram of the system of the present invention;

[0035] Figure 2 This is a precision control diagram of the AST valve group of the present invention;

[0036] Figure 3This is a diagram showing the structural features of the oil circuit in this invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] refer to Figure 1 , Figure 2 and Figure 3 An online maintenance turbine shutdown protection device includes: a high pressure (HP) oil header; a low pressure return (DV) oil header; an OPC overspeed protection oil line; an AST shutdown protection oil header; and a dual redundant AST valve group, which includes a first AST solenoid valve group and a second AST solenoid valve group.

[0039] ASP pressure monitoring unit: connected to the AST shut-off protection oil main pipe, used to monitor the pressure status of the AST shut-off protection oil and detect valve group leakage;

[0040] OPC overspeed protection control oil circuit: connected to the OPC overspeed protection oil line, including at least two OPC solenoid valves (OPC1, OPC2) arranged in parallel.

[0041] Online maintenance isolation device: Installed on the second and fourth oil lines, the online maintenance isolation device is configured to selectively physically isolate the connection between the first and second AST solenoid valve groups and the DV unpressurized return oil header when online maintenance is required; wherein:

[0042] The inlet of the OPC solenoid valve is connected to the HP pressure oil header, and the outlet is connected to the OPC overspeed protection oil line.

[0043] The AST cut-off protection oil header is led out from the first oil circuit upstream of the first group of AST solenoid valves and a check valve. The check valve is set in the first oil circuit and the third oil circuit to prevent oil backflow into the HP pressure oil header.

[0044] The online maintenance isolation device includes a first maintenance shut-off valve installed on the second oil line corresponding to the first group of AST solenoid valves, and a second maintenance shut-off valve installed on the fourth oil line corresponding to the second group of AST solenoid valves.

[0045] The online maintenance isolation device includes a first maintenance solenoid valve installed on the second oil line corresponding to the first group of AST solenoid valves, and a second maintenance solenoid valve installed on the fourth oil line corresponding to the second group of AST solenoid valves.

[0046] refer to Figure 2 The ASP pressure monitoring unit includes: an ASP pressure measurement point, a first precision throttle orifice, a second precision throttle orifice, and an ASP pressure gauge. The first precision throttle orifice is located in the oil circuit upstream of the ASP pressure measurement point, and the second precision throttle orifice is located in the oil circuit downstream of the ASP pressure measurement point leading to the return oil. The ASP pressure gauge is connected to the ASP pressure measurement point for real-time monitoring of the pressure at that point.

[0047] The check valve includes: a first check valve and a second check valve. The first check valve is located in the first oil line at the inlet of the first AST solenoid valve group and is used to prevent oil flow from the first AST solenoid valve group to the HP pressure oil header in reverse. The second check valve is located in the third oil line at the inlet of the second AST solenoid valve group and is used to prevent oil flow from the second AST solenoid valve group to the HP pressure oil header in reverse.

[0048] The OPC overspeed protection control oil circuit also includes an OPC check valve. The OPC check valve is installed on the OPC overspeed protection oil line and is used to prevent oil flow from flowing in reverse from the OPC overspeed protection oil line to the OPC solenoid valve and the DV pressureless return oil header.

[0049] For further reference Figure 3 Pressure test points are set on the oil lines near the inlet and outlet of the first and second AST solenoid valve groups and are used to test the sealing performance and on / off function of the solenoid valves during isolation maintenance.

[0050] Furthermore, the system is configured as follows:

[0051] When a single AST solenoid valve fails, the system redundancy design ensures that the AST shutdown protection oil does not leak and the turbine operates normally. The AST solenoid valve includes any one of AST1, AST2, AST3, and AST4.

[0052] When the first AST solenoid valve group needs to be inspected online, the first inspection shut-off valve or the first inspection solenoid valve is closed or isolated, and the first group of solenoid valves is isolated to take it out of operation. At the same time, the second AST solenoid valve group is confirmed to be working normally through the ASP pressure monitoring unit or pressure test point, and the turbine does not need to be shut down.

[0053] When the second AST solenoid valve group needs to be inspected online, the second inspection shut-off valve or the second inspection solenoid valve is closed or isolated, and the second group of solenoid valves is isolated to take it out of operation. At the same time, the first AST solenoid valve group is confirmed to be working normally through the ASP pressure monitoring unit or pressure test point, and the turbine does not need to be shut down.

[0054] The OPC solenoid valve adopts a parallel redundant design. The OPC solenoid valve includes OPC1 and OPC2, and an OPC pressure gauge is installed on the outlet manifold of the OPC solenoid valve. The OPC pressure gauge is used to monitor the status of the OPC overspeed protection oil.

[0055] The solenoid valves in the first and second AST solenoid valve groups adopt a modular design, which facilitates overall online replacement.

[0056] By real-time monitoring of the ASP oil pressure signal, the AST solenoid valve spool position signal, and the two-way logic cartridge valve spool position signal, three-signal interlocking diagnosis is achieved.

[0057] Diagnostic of AST solenoid valve coil fault: abnormal offset of valve core position signal + loss of ASP oil pressure signal;

[0058] Diagnostic of two-way logic cartridge valve jamming: The AST solenoid valve spool moves successfully, but the ASP oil pressure signal remains unchanged.

[0059] The failure threshold for ASP hydraulic pressure is ±15% of the rated pressure, and the offset threshold for the valve core position sensor is ±0.5 mm of stroke deviation. Operate the valve core mechanical limit mechanism of the two-way logic cartridge valve to lock the valve core in the working position, close the oil inlet shut-off valve corresponding to the faulty AST valve group, disassemble and replace the AST solenoid valve, release the valve core limit, open the oil inlet shut-off valve to restore operation. The AST solenoid valve, such as AST1, adopts a tristable design and is normally in an energized closed state to eliminate coil burnout failure caused by long-term energization. The return port of the two-way logic cartridge valve is equipped with a back pressure check valve to ensure that there is no backflow in the return path during maintenance isolation. All AST solenoid valves and two-way cartridge valves are integrated into a modular valve block. The valve block base has reserved installation interfaces for the oil inlet shut-off valve and valve core limit mechanism.

[0060] In addition, the AST solenoid valve operates under continuous energization. When the unit fails and shuts down, it switches to the shutdown position, releasing the AST oil pressure and closing the unit's air intake valve to achieve shutdown. During normal unit operation, the AST solenoid valve core remains in the energized position, and the ASP oil pressure remains within the operating range.

[0061] The online self-diagnosis function consists of two parts:

[0062] One is real-time process monitoring, which monitors the working status of the AST solenoid valve's energized coil. Under normal operation, the AST solenoid valve is in the working position because the coil is energized. When the coil is damaged, the valve core switches to the closed position under the action of the spring force. The valve core position feedback can monitor this state. At the same time, the switching of the working position of the AST solenoid valve core will cause changes in the ASP oil pressure. The feedback of the two signals can eliminate false alarms and accurately determine the faulty AST solenoid valve.

[0063] Secondly, online operation diagnosis is required. The emergency shutdown device is very important as an emergency shutdown protection device for steam turbines. It is necessary to regularly test the protection function online to ensure it is normal. Both the AST solenoid valve and the two-way logic cartridge valve have valve core position monitoring. During online testing, the AST solenoid valve de-energizes and the valve core of the AST solenoid valve and the two-way logic cartridge valve should leave the working position through the valve core position monitoring. At the same time, it causes the ASP oil pressure to change. The ASP pressure transmitter monitors the change in pressure value to be outside the working oil pressure range.

[0064] When the AST solenoid valve is de-energized and operates, the valve core position is monitored by the valve core position. If the valve core is in the closed position and the ASP oil pressure is still within the normal operating range, it can be determined that the valve core jamming fault of the two-way logic cartridge valve can be detected by the valve core position monitoring.

[0065] When the AST solenoid valve loses power, if the valve core is in the working position and the ASP oil pressure is within the normal range, and the two-way logic cartridge valve core does not move, it can be determined that the AST solenoid valve core is stuck.

[0066] By monitoring the valve core position of the AST solenoid valve, the valve core position of the two-way logic cartridge valve, and the ASP oil pressure value, the working status of the trip protection device can be accurately determined online.

[0067] Online maintenance function: Considering the high failure rate of the solenoid valve in this protection device, an online maintenance function was designed for the maintenance of the solenoid valve during the optimization design. When the AST solenoid valve is detected by the online diagnostic function, the valve core limit function on the two-way cartridge valve can be used to limit the valve core of the two-way cartridge valve to the working position to prevent malfunction and unit shutdown. Then, the oil inlet shut-off valve in front of the solenoid valve is closed. The oil return circuit of the solenoid valve is equipped with a check valve to isolate the oil return circuit. At this time, the solenoid valve can be removed for maintenance and replacement. After the replacement is completed, the oil inlet shut-off valve is opened to disengage the valve core limit function of the two-way cartridge valve. At this time, the trip protection device returns to normal working state.

[0068] Real-time status monitoring and precise diagnostics enable potential faults to be detected and addressed early, avoiding major safety hazards caused by hidden faults leading to protection failure. The online maintenance mechanism ensures that even during fault handling, another redundant AST valve group maintains normal shut-off protection. Furthermore, physical locking of the two-way valve and dual isolation of the oil source completely eliminate the risk of unplanned shutdowns triggered by online maintenance operations. The ASP pressure monitoring system, as a key redundant monitoring system, further ensures the reliability of the system status and avoids resource consumption caused by frequent shutdowns for maintenance. The ability to quickly replace AST solenoid valves online significantly reduces maintenance difficulty and time costs. Precise diagnostics prevent over-maintenance or unnecessary backups due to misjudgments. This minimizes component waste, while ensuring timely detection, accurate location, and rapid repair of faults, resulting in a healthier and more reliable operating state for the entire shutdown protection system. The dual redundancy design of the AST solenoid valve group, combined with diagnostic and maintenance capabilities, constitutes a robust fault-tolerant mechanism, greatly enhancing the overall stability and resilience of the system. Diagnostic information, through signal output position and pressure, enables remote centralized monitoring and intelligent alarms. The user interface is more user-friendly, and the online maintenance operation steps are clearly defined: lock-out -> isolation -> replacement -> recovery. The skill requirements for maintenance personnel are relatively reasonable. Core components of the system, such as solenoid valves with feedback, two-way cartridge valves, and shut-off valves, can be integrated into modular valve blocks, resulting in a compact design with minimal modifications to the original system, facilitating retrofitting on existing units.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A turbine shutdown protection device for online maintenance, characterized in that, include: High pressure (HP) manifold; Unpressurized return oil (DV) header; OPC overspeed protection oil lines; AST cut-off protection oil header; A dual-redundant AST valve group, comprising a first AST solenoid valve group and a second AST solenoid valve group. ASP pressure monitoring unit: connected to the AST shutdown protection oil main pipe, used to monitor the pressure status of the AST shutdown protection oil and detect valve group leakage; OPC overspeed protection control oil circuit: connected to the OPC overspeed protection oil line, including at least two OPC solenoid valves (OPC1, OPC2) arranged in parallel. Online maintenance isolation device: installed on the second and fourth oil lines, the online maintenance isolation device is configured to selectively physically isolate the connection between the first or second group of AST solenoid valves and the DV unpressurized return oil header when online maintenance is required; wherein: The inlet of the OPC solenoid valve is connected to the HP pressure oil header, and the outlet is connected to the OPC overspeed protection oil line. The AST interruption protection oil header is at least led out from the first oil circuit upstream of the first group of AST solenoid valves and includes a check valve. The check valve is installed on the first oil circuit and the third oil circuit to prevent oil backflow into the HP pressure oil header.

2. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that: The online maintenance isolation device includes a first maintenance shut-off valve located on the second oil line corresponding to the first group of AST solenoid valves, and a second maintenance shut-off valve located on the fourth oil line corresponding to the second group of AST solenoid valves.

3. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that: The online maintenance isolation device includes a first maintenance solenoid valve located on the second oil line corresponding to the first group of AST solenoid valves, and a second maintenance solenoid valve located on the fourth oil line corresponding to the second group of AST solenoid valves.

4. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that, The ASP stress monitoring unit includes: The system includes an ASP pressure measurement point, a first precision throttle orifice, a second precision throttle orifice, and an ASP pressure gauge. The first precision throttle orifice is located in the oil passage upstream of the ASP pressure measurement point, and the second precision throttle orifice is located in the oil passage downstream of the ASP pressure measurement point leading to the return oil. The ASP pressure gauge is connected to the ASP pressure measurement point for real-time monitoring of the pressure at that point.

5. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that, The one-way valve includes: A first check valve and a second check valve are provided. The first check valve is located in the first oil line at the inlet of the first AST solenoid valve group and is used to prevent oil flow from the first AST solenoid valve group to the HP pressure oil header in reverse. The second check valve is located in the third oil line at the inlet of the second AST solenoid valve group and is used to prevent oil flow from the second AST solenoid valve group to the HP pressure oil header in reverse.

6. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that, The OPC overspeed protection control oil circuit also includes an OPC check valve, which is installed on the OPC overspeed protection oil line and is used to prevent oil flow from flowing in the opposite direction from the OPC overspeed protection oil line to the OPC solenoid valve and the DV pressureless return oil header.

7. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that, It also includes pressure test points, which are set on the oil lines near the inlet and outlet of the first group of AST solenoid valves and the second group of AST solenoid valves, and are used to test the sealing performance and on / off function of the solenoid valves during isolation maintenance.

8. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that, The system is configured as follows: When a single AST solenoid valve fails, the system redundancy design ensures that the AST shutdown protection oil does not leak and the turbine operates normally. The AST solenoid valve includes any one of AST1, AST2, AST3, and AST4. When the first group of AST solenoid valves needs to be inspected online, the first inspection shut-off valve or the first inspection solenoid valve is closed or isolated, and the first group of solenoid valves is isolated to stop working. At the same time, the second group of AST solenoid valves is confirmed to be working normally through the ASP pressure monitoring unit or pressure test point, and the turbine does not need to be shut down. When the second group of AST solenoid valves needs to be inspected online, the second inspection shut-off valve or the second inspection solenoid valve is closed or isolated, and the second group of solenoid valves is isolated to stop its operation. At the same time, the first group of AST solenoid valves is confirmed to be working normally through the ASP pressure monitoring unit or pressure test point, and the turbine does not need to be shut down.

9. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that: The OPC solenoid valve adopts a parallel redundant design. The OPC solenoid valve includes OPC1 and OPC2, and an OPC pressure gauge is installed on the outlet manifold of the OPC solenoid valve. The OPC pressure gauge is used to monitor the status of the OPC overspeed protection oil.

10. The turbine shutdown protection device capable of online maintenance according to claim 1, characterized in that: The solenoid valves in the first and second AST solenoid valve groups adopt a modular design, which facilitates overall online replacement.

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