Method for actively preventing ESD valve of natural gas pressure regulating station from being closed by mistake

Abstract

The invention relates to the technical field of gas safety, in particular to a method for actively preventing an ESD (Electro-Static Discharge) valve of a natural gas pressure regulating station from being closed by mistake. The ESD valve control system solves the technical problems that in the prior art, an ESD valve control system of a gas power plant has single-point fault hidden danger, and system risks caused by faults of a single element are difficult to eliminate fundamentally. According to the technical scheme, the method for actively preventing the ESD valve of the natural gas pressure regulating station from being closed by mistake comprises a gas supply loop redundancy transformation step, a power supply loop redundancy transformation step, a UPS bypass switching transformation step and a control loop insurance transformation step. According to the ESD valve control system, a double-guarantee system of gas circuit parallel redundancy and circuit independent redundancy is constructed, and a method of power supply bypass backup and loop insurance separation is supplemented, so that a single fault point existing in the ESD valve control system is eliminated, a system which has a fault, i.e., tripping, originally is converted into a system which can allow a single or even multiple element faults, and the system reliability is improved. And the operation reliability and the availability rate of the gas unit are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of gas safety technology, and in particular to a method for actively preventing accidental closure of ESD valves in natural gas pressure regulating stations. Background Technology

[0002] As an important peak-shaving power source, the reliability of gas-fired power plants directly affects the stability of the power grid. In gas-fired power plants, the natural gas pressure regulating station is a key utility system that supplies fuel to the gas turbine units. The emergency shut-off valve installed on its main gas intake pipeline is the last line of defense to ensure the safety of the entire plant. This ESD valve must usually be kept open during normal operation of the unit and should only be quickly closed in case of emergencies such as fire.

[0003] Currently, many ESD valve control designs in operating power plants have potential single-point-of-failure vulnerabilities. Specifically: the compressed air circuit controlling the ESD valve's operation typically consists of only one set, with two solenoid valves connected in series. If either solenoid valve fails to operate due to power loss or its own malfunction, it will cause a depressurization of the control air supply, leading to the ESD valve's erroneous closure. Furthermore, the power supply for the solenoid valves is usually provided by a single UPS unit, converted by a DC / DC switching power supply. If the UPS fails, the switching power supply fails, or the only fuse in the circuit blows, all solenoid valves will lose power, causing the ESD valves to close erroneously. Additionally, the original UPS system lacks an automatically switching bypass power supply. When the UPS unit itself requires maintenance or experiences an internal fault, it will cause an output interruption, resulting in a power outage in the control circuit.

[0004] Therefore, to address the above problems, a method for actively preventing accidental closure of ESD valves in natural gas pressure regulating stations is proposed. By constructing redundant gas supply and power supply circuits and optimizing the control power supply configuration, the risk of accidental closure of ESD valves due to failure of a single component is eliminated. Summary of the Invention

[0005] In order to overcome the potential single-point failure of the ESD valve control system in the existing gas-fired power plant, it is difficult to fundamentally eliminate the system risk caused by the failure of a single component.

[0006] The technical solution of this invention is: a method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station, comprising the following steps:

[0007] Redundancy modification steps for the air supply circuit: Add a compressed air control circuit to the control air source pipeline of the ESD valve to form a series-parallel structure with the original compressed air control circuit; Redundancy upgrade steps for power supply circuit: Add an uninterruptible power supply (UPS) device and a 24VDC power module to power the newly added solenoid valve. The input power of the new UPS device comes from a different power access point than the original UPS device. UPS bypass switching modification steps: Add a bypass power input and UPS / bypass automatic switching circuit to the original UPS unit; Control circuit fuse modification steps: The original shared fuse of the solenoid valve power supply circuit is split into multiple independent fuses.

[0008] Preferably, a compressed air control circuit is added to the control air source pipeline of the ESD valve through the air supply circuit redundancy modification step, forming a series-parallel structure with the original compressed air control circuit. A UPS device and a 24VDC power module are added through the power supply circuit redundancy modification step to power the newly added solenoid valve. The input power of the new UPS device comes from a different power access point than the original UPS device. A bypass power input and UPS / bypass automatic switching circuit are added to the original UPS device through the UPS bypass switching modification step. The common fuse of the original solenoid valve power supply circuit is split into multiple independent fuses through the control circuit fuse modification step. In this way, multiple redundancy protections are built simultaneously from the pneumatic control source and the electrical control end, so that the control system of the ESD valve no longer has a single point of failure.

[0009] Preferably, in the redundant modification step of the air supply circuit, the addition of a compressed air control circuit includes: after being drawn from the compressed air source, it passes through a manual valve and a first pressure reducing filter in sequence, and then branches into a first circuit and a second circuit. The first circuit is connected to the original solenoid valve sequence, and the second circuit passes through the second pressure reducing filter and is connected to the newly added solenoid valve sequence. The original solenoid valve sequence and the new solenoid valve sequence are connected in parallel and then connected to the control port of the ESD valve.

[0010] Preferably, the original solenoid valve sequence includes a first solenoid valve and a second solenoid valve connected in series, and the new solenoid valve sequence includes a third solenoid valve and a fourth solenoid valve connected in series, wherein the outlets of the first solenoid valve and the third solenoid valve are respectively connected to the inlets of the second solenoid valve and the fourth solenoid valve, and the outlets of the second solenoid valve and the fourth solenoid valve are jointly connected to the control port of the ESD valve.

[0011] Preferably, the first, second, third, and fourth solenoid valves each have an inlet, an outlet, and an exhaust port, with the exhaust port opening and the inlet closing when power is lost.

[0012] Preferably, in the power supply circuit redundancy modification step, the output power of the new UPS device is converted to 24VDC by the 24VDC power module and then used to power the newly added solenoid valve.

[0013] Preferably, in the UPS bypass switching modification step, the bypass power input comes from the plant power system, and the automatic switching circuit includes a contactor and a relay for detecting UPS output faults and automatically switching to bypass power supply.

[0014] Preferably, in the control circuit fuse modification step, the original solenoid valve power supply circuit includes a first solenoid valve and a second solenoid valve, and the original shared fuse is split into a first independent fuse and a second independent fuse, which correspond to the power supply circuits of the first solenoid valve and the second solenoid valve, respectively.

[0015] As a preferred option, the control logic modification step is also included: integrating the control logic of the newly added solenoid valve with that of the original solenoid valve, so that the DCS remote open / close signal and the operator's console emergency shut-off signal can simultaneously control all solenoid valves.

[0016] Preferably, in the control logic modification step, it is ensured that when any gas turbine unit is operating normally, all solenoid valves are energized and the ESD valve is open; when an emergency occurs, all solenoid valves are de-energized and the ESD valve is closed.

[0017] Preferably, in the gas supply circuit redundancy modification step and the power supply circuit redundancy modification step, the newly added components are physically isolated from the original components.

[0018] The beneficial effects of this invention are: This invention adds a parallel control gas path with an independent filter to the gas path and incorporates a new series solenoid valve group, forming a hybrid series and parallel gas path, so that a single solenoid valve failure no longer leads to gas supply loss. Secondly, in terms of circuitry, a completely independent power supply system from power input, UPS to DC / DC power is configured for the new solenoid valve group, forming a high-reliability power network together with the original UPS system equipped with automatic bypass switching function. By splitting fuses and integrating control logic, the isolation of fault range and the unification of control are achieved. Thus, a dual protection system of parallel redundancy of gas path and independent redundancy of circuit is constructed, supplemented by power bypass backup and loop fuse separation methods, thereby fundamentally eliminating the single fault point in the ESD valve control system, transforming the system that would trip upon failure into a system that can tolerate single or even multiple component failures, significantly improving the operational reliability and availability of the gas turbine unit. Attached Figure Description

[0019] Figure 1 The diagram shown is a gas circuit connection diagram of the natural gas pressure regulating station ESD valve active anti-misoperation method of the present invention. Figure 2 The diagram shown illustrates the gas circuit connection control principle of the active anti-misoperation method for the ESD valve of the natural gas pressure regulating station according to the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Example 1 Please see Figure 1 and Figure 2 This invention provides an embodiment: a method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station, comprising the following steps: Redundancy modification steps for the air supply circuit: Add a compressed air control circuit to the control air source pipeline of the ESD valve to form a series-parallel structure with the original compressed air control circuit; Redundancy upgrade steps for power supply circuit: Add an uninterruptible power supply (UPS) device and a 24VDC power module to power the newly added solenoid valve. The input power of the new UPS device comes from a different power access point than the original UPS device. UPS bypass switching modification steps: Add a bypass power input and UPS / bypass automatic switching circuit to the original UPS unit; Control circuit fuse modification steps: The original shared fuse of the solenoid valve power supply circuit is split into multiple independent fuses.

[0022] Specifically, the system involves several steps: First, a compressed air control circuit is added to the control air supply line of the ESD valve through a redundant air supply circuit modification step, forming a series-parallel structure with the original compressed air control circuit. Second, an uninterruptible power supply (UPS) device and a 24VDC power module are added to power the newly added solenoid valve through a redundant power supply circuit modification step. The input power of the new UPS device comes from a different power access point than the original UPS device. Third, a bypass power input and UPS / bypass automatic switching circuit are added to the original UPS device through a UPS bypass switching modification step. Fourth, the common fuse of the original solenoid valve power supply circuit is split into multiple independent fuses through a control circuit fuse modification step. This achieves multiple redundancy protection from the pneumatic control source and the electrical control end, ensuring that the ESD valve control system no longer has a single point of failure.

[0023] Furthermore, in the redundant modification step of the air supply circuit, an additional compressed air control circuit is added, which includes: after being drawn from the compressed air source, it passes through a manual valve and a first pressure reducing filter in sequence, and then branches into a first line and a second line. The first line is connected to the original solenoid valve sequence, and the second line passes through the second pressure reducing filter and then connects to the newly added solenoid valve sequence. The original solenoid valve sequence and the new solenoid valve sequence are connected in parallel to the control port of the ESD valve. By adding an independent air path and connecting it in parallel with the original air path, a dual-channel air supply pattern is formed. The two pressure reducing filters ensure the independence and pressure stability of the old and new air sources. Thus, if any air source or its auxiliary filter becomes blocked or leaks, the other line can still maintain the pressure of the ESD valve control air source, providing continuous and stable pneumatic power to the core control components.

[0024] Furthermore, the original solenoid valve sequence includes a first and a second solenoid valve connected in series, while the new solenoid valve sequence includes a third and a fourth solenoid valve connected in series. The outlets of the first and third solenoid valves are connected to the inlets of the second and fourth solenoid valves, respectively, and the outlets of the second and fourth solenoid valves are connected together to the control port of the ESD valve. This configuration constitutes a hybrid logic of series followed by parallel. In each independent air path, two solenoid valves are connected in series, following "AND" logic, which improves the safety of a single path. The two independent series air paths are connected in parallel, following "OR" logic. Thus, the air supply to that path will only be interrupted when both solenoid valves in the same path are simultaneously de-energized or malfunction. If one path fails, the other path can still keep the ESD valve open, achieving a balance between safety and reliability.

[0025] Furthermore, the first, second, third, and fourth solenoid valves all have inlets, outlets, and exhaust ports. When power is lost, the exhaust port opens and the inlet closes. When the solenoid valves are energized, they connect the inlet and outlet to establish control air pressure. When power is lost, they automatically cut off the inlet and connect the outlet and exhaust port to quickly release the control air pressure and drive the ESD valve to close in an emergency. This modification utilizes this characteristic, but redundant design ensures that it will not be accidentally triggered in non-emergency situations.

[0026] Furthermore, in the power supply circuit redundancy upgrade step, the output power of the new UPS unit is converted to 24VDC by the 24VDC power module to power the newly added solenoid valves. This step establishes a completely independent power supply system for the newly added solenoid valve sequence. The input power of the new UPS is taken from different access points, which avoids the risk of both systems losing power at the same time due to the failure of a single power supply in the upper stage. The independent 24VDC power module also avoids mutual interference with the original system power module, forming electrical isolation redundancy.

[0027] Furthermore, in the UPS bypass switching modification step, the bypass power input comes from the plant power system, and the automatic switching circuit includes contactors and relays to detect UPS output faults and automatically switch to bypass power supply. When the original UPS main unit fails, causing abnormal or interrupted output voltage, the detection element in the switching circuit will act quickly, driving the contactor to switch the load from the UPS main unit output to the bypass power supply directly supplied by the plant power system in a very short time, thereby ensuring that the control power supply is not interrupted during the failure of the original UPS main unit.

[0028] Furthermore, in the control circuit fuse modification step, the original solenoid valve power supply circuit includes a first solenoid valve and a second solenoid valve. The original shared fuse is split into a first independent fuse and a second independent fuse, corresponding to the power supply circuits of the first solenoid valve and the second solenoid valve, respectively. When a solenoid valve's dedicated fuse blows due to an internal short circuit or other fault, only that solenoid valve fails, while the other solenoid valve in the same channel and its power supply circuit are unaffected. Combined with the pneumatic redundancy design, the system function can still be maintained, reducing the probability of system failure caused by minor faults.

[0029] Furthermore, the control logic modification steps include integrating the control logic of the newly added solenoid valves with that of the original solenoid valves, so that the DCS remote open / close signals and the operator's console emergency shut-off signals can simultaneously control all solenoid valves. The modification does not change the operator's operating habits or the original control logic. All valve opening and closing commands are sent to all four solenoid valves in parallel, which ensures that all solenoid valves act in a consistent manner during normal operation or emergency shutdown, thus ensuring the uniformity and determinism of control.

[0030] Furthermore, in the control logic modification steps, ensure that when any gas turbine unit is operating normally, all solenoid valves are energized and ESD valves are open; when an emergency occurs, all solenoid valves are de-energized and ESD valves are closed; maintain all redundant systems in operation under normal conditions, and ensure that all redundant channels respond synchronously under emergency conditions.

[0031] Furthermore, in the gas supply circuit redundancy modification steps and power supply circuit redundancy modification steps, the newly added components are physically isolated from the original components; physical isolation can prevent the new and old equipment from being damaged simultaneously by a single event such as local physical collision, fire, or dripping water, further improving the actual reliability of the redundant system.

[0032] Through the above steps, by adding a parallel control gas path with an independent filter and implanting a new series solenoid valve group, a hybrid series and parallel gas path is formed, ensuring that a single solenoid valve failure no longer leads to gas supply loss. Secondly, in terms of circuitry, a completely independent power supply system from power input, UPS to DC / DC power is configured for the new solenoid valve group, forming a high-reliability power network together with the original UPS system equipped with automatic bypass switching function. By splitting fuses and integrating control logic, fault isolation and unified control are achieved. This constructs a dual protection system of parallel redundancy in the gas path and independent redundancy in the circuit, supplemented by power bypass backup and circuit fuse separation methods, fundamentally eliminating the single fault point in the ESD valve control system. The system, which originally tripped upon failure, is transformed into a system that can tolerate single or even multiple component failures, significantly improving the operational reliability and availability of the gas turbine unit.

[0033] Example 2 Optionally, the present invention provides another embodiment, which provides a method for actively preventing accidental closure of the ESD valve in a natural gas pressure regulating station, specifically implemented according to the following steps: S101: Redundancy Upgrade of Gas Supply Circuit On the existing compressed air control pipeline of the ESD valve in the pressure regulating station, an independent compressed air control loop is added in parallel. In specific implementation, a pipeline is led out from the main manual valve of the original compressed air source and forms the first branch point (P1) through a tee connector. Starting from point P1, one path is connected to the original first pressure reducing filter (F1) to form the "original air path channel"; the other path is connected to the newly installed second pressure reducing filter (F2) to form the "new air path channel". The outlet pipelines of the two pressure reducing filters eventually merge and are connected to the control air ports (PILOT port and IN port) of the main air control valve of the ESD valve. This modification ensures that if any air path is blocked or leaked, the other path can still maintain the pressure of the ESD valve control air source. S102: Redundancy Upgrade of Power Supply Circuit A new UPS unit and a 24VDC power module were added near the UPS power cabinet of the voltage regulating station. The AC input power of the new UPS unit was taken from a different distribution box or busbar than that of the original UPS unit, thus achieving electrical isolation from the source. The output of the new UPS unit was connected to the input of the newly installed 24VDC switching power supply. The output of the 24VDC switching power supply was used to power the newly added #3 and #4 solenoid valves. This modification established a completely independent and isolated power supply system for the newly added solenoid valves from power input to DC output. S103: UPS Bypass Switching Retrofit The original UPS unit was modified by adding a bypass power input. This bypass power supply is directly drawn from the highly reliable AC 220V power supply circuit in the plant's power system. An automatic switching circuit consisting of contactors, voltage detection relays, and other components was added to the output circuit of the original UPS unit. This circuit continuously monitors the output voltage of the original UPS main unit. When an abnormal output voltage (undervoltage, overvoltage, or loss of voltage) is detected, the voltage relay activates, driving the contactor to switch the load from the UPS main unit output to the bypass power supply within milliseconds. The switching process is completed automatically without manual intervention, ensuring continuous power supply to the original solenoid valves and control circuits. S104: Control circuit fuse upgrade The fuse configuration in the original solenoid valve power supply circuit was modified. The fuse shared by the first solenoid valve (SOL1) and the second solenoid valve (SOL2) in the original design was removed. Instead, an independent fuse was connected in series in the power supply circuits of SOL1 and SOL2, namely the first independent fuse and the second independent fuse. The specifications of the two fuses were selected based on the rated current of the individual solenoid valves. This modification achieved microscopic isolation of the power supply circuit, preventing the failure of a single solenoid valve from causing the other solenoid valve in the same channel to lose power. By implementing the above four steps in a coordinated manner, the risk of ESD valves being accidentally shut off due to a single solenoid valve failure, a single power supply failure, or a single fuse blown is fundamentally eliminated.

[0034] Example 3 Optionally, this embodiment provides a more specific gas path implementation and control logic scheme based on embodiment 2.

[0035] In this embodiment, steps S102, S103, and S104 are the same as in Example 2, and step S101 is implemented in the following more specific manner: S201: Detailed Gas Connections After passing through the main manual valve (V1), the compressed air path is divided into two branches at the first branch point (P1); Original gas path: A pipeline is led out from P1 and connected sequentially to the first pressure reducing filter (F1); the outlet of F1 is connected to the second branch point (P2); a pipeline led out from P2 is directly connected to the IN port of the main gas control valve on one side and to the fourth branch point (P4) on the other side; a pipeline led out from P4 is connected to interface 2 of the first solenoid valve (SOL1); interface 1 of SOL1 is connected to the fifth branch point (P5); a pipeline led out from P5 is connected to interface 2 of the second solenoid valve (SOL2); interface 1 of SOL2 is finally connected to the PILOT port of the main gas control valve; New air path: Another branch line is drawn from P1 and connected sequentially to the second pressure reducing filter (F2); the outlet of F2 is connected to the third branch point (P3); the branch line from P3 is directly connected to the IN port of the main air control valve (merging with the air path from P2), and also connected to port 2 of the third solenoid valve (SOL3); port 1 of SOL3 is connected to port 2 of the fourth solenoid valve (SOL4); port 1 of SOL4 is finally connected to the PILOT port of the main air control valve (merging with the air path from SOL2). All solenoid valves (SOL1, SOL2, SOL3, SOL4) are two-position three-way normally closed solenoid valves. That is, when the solenoid valve coil is de-energized, its air inlet is closed and its air outlet is connected to the exhaust port to achieve rapid exhaust. S202: Control Logic Integration The control signal lines of the newly added #3 and #4 solenoid valves are connected in parallel with the control signal lines of the original #1 and #2 solenoid valves. In specific implementation, the "ESD valve open" command (DO) output point from the DCS is simultaneously connected in parallel to the power supply circuits of the original #1 and #2 solenoid valves and the new #3 and #4 solenoid valves. Similarly, the normally closed contact of the "emergency close" button from the control panel is connected in series to the common power supply circuit of the above four solenoid valves. In this way, when the DCS issues a valve open command, all four solenoid valves are energized simultaneously; when the emergency button on the control panel is pressed or the DCS issues a valve close command, all four solenoid valves are de-energized simultaneously. This logic ensures that all solenoid valves are energized (ESD valve open) during normal unit operation and that all solenoid valves are de-energized synchronously (ESD valve closes quickly) in an emergency.

[0036] This implementation method, through a series-to-parallel gas path design and unified control logic, improves reliability while ensuring the execution of the safety shutdown function.

[0037] Example 4 Optionally, this embodiment provides a more reliable implementation scheme based on embodiments 2 and 3.

[0038] Specifically: S301: Independent power supply implementation In S102, the newly added UPS unit preferably draws its input power from a switch cabinet on a different busbar section from the original UPS unit in the plant's 380V / 220V power distribution system to achieve maximum power isolation; the newly added 24VDC power module must have a rated power that meets the requirement of simultaneously driving two solenoid valves, #3 and #4, with an appropriate margin; its positive and negative output terminals are respectively connected to the newly laid power supply cables to solenoid valves #3 and #4. S302: Specific configuration of bypass switching circuit In S103, the specific component selection and connection of the bypass power automatic switching circuit are as follows: Select a voltage monitoring relay with a rated voltage of AC220V, and connect its monitoring terminals in parallel to the output terminal of the original UPS device (i.e., the input terminal of the switching circuit); select a three-phase or single-phase (depending on the number of UPS output phases) AC contactor as the switching switch; connect a pair of normally closed contacts of the voltage relay in series with the coil circuit of the AC contactor; when the UPS output is normal, the voltage relay is energized, its normally closed contacts are open, the contactor does not operate, and the load is powered by the UPS host; when the UPS output is abnormal, the voltage relay is de-energized and reset, its normally closed contacts are closed, the contactor coil is energized and energized, and its main contacts switch the load to be powered by the bypass power supply; S303: Independent Insurance Configuration In S104, the first independent fuse (for SOL1) and the second independent fuse (for SOL2) should be installed in the 24VDC power distribution circuit after the original UPS output is converted by the switching power supply; the installation positions of the two fuse holders should be clearly marked for easy maintenance and replacement; the selection of the fuse rated current value (I_fuse) can be based on the following principles: I_fuse = k I_coil Where I_coil is the rated operating current of a single solenoid valve coil, and k is the safety factor, typically taken as 1.5 to 2.0; this configuration ensures that the fuse can blow quickly in the event of a short circuit in the solenoid valve coil, while preventing accidental blowing due to normal starting current; S304: Physical isolation installation When implementing S101 and S102, the newly added equipment components are physically isolated during installation. Specifically, the newly installed second pressure reducing filter (F2), third solenoid valve (SOL3), and fourth solenoid valve (SOL4) should be assembled on a new valve assembly rack, which should maintain a certain safe distance (e.g., greater than 0.5 meters) from the original pneumatic control cabinet or the original solenoid valve assembly (SOL1, SOL2) or be installed in a different protective enclosure. Similarly, the newly added UPS unit and 24VDC power module should also be installed in a new cabinet physically separate from the original UPS power cabinet. This physical isolation effectively prevents the simultaneous damage to both the old and new systems due to a single event such as a local fire, dripping water, or mechanical impact.

[0039] This implementation method constructs a reliable ESD valve anti-misclosing system through electrical and physical isolation measures combined with component configuration, which can effectively cope with various complex fault conditions.

[0040] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station, characterized in that: Includes the following steps: Redundancy modification steps for the air supply circuit: Add a compressed air control circuit to the control air source pipeline of the ESD valve to form a series-parallel structure with the original compressed air control circuit; Redundancy upgrade steps for power supply circuit: Add an uninterruptible power supply (UPS) device and a 24VDC power module to power the newly added solenoid valve. The input power of the new UPS device comes from a different power access point than the original UPS device. UPS bypass switching modification steps: Add a bypass power input and UPS / bypass automatic switching circuit to the original UPS unit; Control circuit fuse modification steps: The original shared fuse of the solenoid valve power supply circuit is split into multiple independent fuses.

2. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 1, characterized in that: In the redundant modification step of the air supply circuit, the addition of a compressed air control circuit includes: after being drawn from the compressed air source, it passes through a manual valve and a first pressure reducing filter in sequence, and then branches into a first circuit and a second circuit. The first circuit is connected to the original solenoid valve sequence, and the second circuit passes through the second pressure reducing filter and is connected to the newly added solenoid valve sequence. The original solenoid valve sequence and the new solenoid valve sequence are connected in parallel and then connected to the control port of the ESD valve.

3. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 2, characterized in that: The original solenoid valve sequence includes a first solenoid valve and a second solenoid valve connected in series, and the new solenoid valve sequence includes a third solenoid valve and a fourth solenoid valve connected in series, wherein the outlets of the first solenoid valve and the third solenoid valve are respectively connected to the inlets of the second solenoid valve and the fourth solenoid valve, and the outlets of the second solenoid valve and the fourth solenoid valve are jointly connected to the control port of the ESD valve.

4. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 3, characterized in that: The first, second, third, and fourth solenoid valves each have an inlet, an outlet, and an exhaust port. When power is lost, the exhaust port opens and the inlet closes.

5. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 1, characterized in that: In the power supply circuit redundancy modification step, the output power of the new UPS device is converted to 24VDC by the 24VDC power module and then used to power the newly added solenoid valve.

6. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 1, characterized in that: In the UPS bypass switching modification step, the bypass power input comes from the plant power system, and the automatic switching circuit includes a contactor and a relay, which are used to detect UPS output faults and automatically switch to bypass power supply.

7. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 1, characterized in that: In the control circuit fuse modification step, the original solenoid valve power supply circuit includes a first solenoid valve and a second solenoid valve. The original shared fuse is split into a first independent fuse and a second independent fuse, which correspond to the power supply circuits of the first solenoid valve and the second solenoid valve, respectively.

8. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 1, characterized in that: It also includes a control logic modification step: integrating the control logic of the newly added solenoid valves with that of the original solenoid valves, so that the DCS remote open / close signals and the operator console emergency shut-off signals can simultaneously control all solenoid valves.

9. A method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 8, characterized in that: In the control logic modification steps, ensure that when any gas turbine unit is operating normally, all solenoid valves are energized and the ESD valve is open; when an emergency occurs, all solenoid valves are de-energized and the ESD valve is closed.

10. The method for actively preventing accidental closure of an ESD valve in a natural gas pressure regulating station according to claim 1, characterized in that: In the gas supply circuit redundancy modification step and the power supply circuit redundancy modification step, the newly added components are physically isolated from the original components.

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