Self-powered all-solid-state rail potential limiting device and control method thereof

Abstract

This invention provides a self-powered, all-solid-state rail potential limiting device and its control method, relating to the field of electrified rail transit technology. The device includes a fully sealed protective housing and housed within the housing a self-powered module, an all-solid-state switch module, an intelligent main control module, and an isolation drive and heat dissipation module. The device is electrically connected to the rail via a rail connection cable and to the integrated grounding grid via a grounding down conductor. The isolation drive and heat dissipation module is positioned between the intelligent main control module and the all-solid-state switch module. The intelligent main control module is electrically connected to the all-solid-state switch module, the self-powered module, and the isolation drive and heat dissipation module. The self-powered module converts the potential difference signal collected by the isolation drive and heat dissipation module into DC power to supply power to the intelligent main control module and the isolation drive and heat dissipation module. This invention solves the problems of traditional devices relying on external power supply and the difficulty of energy acquisition in passive operating conditions under long tunnels.

Description

Technical Field

[0001] This invention relates to the field of electrified rail transit technology, and more specifically, to a self-powered, all-solid-state rail potential limiting device and its control method. Background Technology

[0002] As my country's electrified railway network continues to expand into mountainous and complex geographical environments, the safety and stability of railway integrated grounding systems and traction return current systems are receiving increasing attention. In recent years, incidents of abnormally high rail potential caused by traction return current system failures have occurred frequently. Furthermore, in long tunnels and remote mountainous sections, the proportion of device failures due to difficulties in external power supply and inconvenient equipment maintenance is increasing year by year. Such protection failures not only threaten train operation safety but also necessitate frequent manual inspections and equipment replacements by maintenance departments, significantly increasing the overall lifecycle operating costs. Therefore, rail potential limiting devices must possess excellent environmental adaptability and intelligent operation and maintenance capabilities to ensure the stable operation of the traction power supply system and the long-term safety of trains.

[0003] Studies have shown that changes in traction load and short-circuit faults are the main factors causing rail potential fluctuations. When traction current flows through the rail circuit, it is affected by impedance, generating a potential difference to ground, which in turn leads to the risk of insulation breakdown, causing signal equipment to burn out and seriously affecting the train control system. Rail potential is also closely related to the external electromagnetic environment. When trains pass through areas of heavy thunderstorms or high-impedance geological sections, lightning surges or overhead contact line overvoltages can enter the rail circuit through inductive coupling. At this time, traditional protection devices often cannot distinguish between transient lightning overvoltages and continuous short-circuit overvoltages, making them prone to malfunction.

[0004] Furthermore, electrified railways often have complex terrain, with numerous long tunnels and viaducts, making it difficult to lay a stable AC 220V external power supply in these areas. Laying low-voltage cables over long distances not only results in large voltage fluctuations and low power supply reliability but also in extremely high construction costs. Traditional active protection devices rely entirely on external auxiliary power; if this external auxiliary power is interrupted, the device will completely fail, leaving the rails unprotected and creating a huge safety blind spot. Summary of the Invention

[0005] The purpose of this invention is to provide a self-powered, all-solid-state rail potential limiting device and its control method to improve the aforementioned problems. To achieve the above objective, the technical solution adopted by this invention is as follows:

[0006] In a first aspect, this application provides a self-powered all-solid-state rail potential limiting device, the device comprising a fully sealed protective housing and a self-powered module, an all-solid-state switch module, an intelligent main control module and an isolation drive and heat dissipation module housed within the fully sealed protective housing;

[0007] The device is electrically connected to the rail via a rail connection cable, and connected to the integrated grounding grid via a grounding down conductor;

[0008] The isolation drive and heat dissipation module is disposed between the intelligent main control module and the all-solid-state switch module;

[0009] The intelligent main control module is electrically connected to the all-solid-state switch module, the self-powered module, and the isolation drive and heat dissipation module, respectively.

[0010] The self-powered module converts the potential difference signal collected by the isolation drive and heat dissipation module into DC power to power the intelligent main control module and the isolation drive and heat dissipation module.

[0011] Secondly, this application also provides a control method for a self-powered, all-solid-state rail potential limiting device, comprising:

[0012] The potential difference signal between the rail and the ground is collected in real time by a self-powered all-solid-state rail potential limiting device to obtain the rail potential amplitude;

[0013] The operating mode of the self-powered all-solid-state rail potential limiting device is switched according to the rail potential amplitude. The operating modes include a sleep mode and a full-speed operating mode.

[0014] If in sleep mode, a hybrid energy management strategy based on wide voltage potential difference is implemented to maintain low power consumption and continuously collect rail potential amplitude.

[0015] If it is in full-speed operation mode, the rail potential signal is sampled at high speed to obtain voltage time series data;

[0016] By performing joint feature identification in the time and frequency domains and judging rail faults using the voltage time series data, fault identification results are obtained. The fault identification results include power frequency short circuit faults, power frequency overvoltage faults, and lightning interference / operational overvoltage conditions.

[0017] Based on the fault identification results, the corresponding fault handling actions are executed, and the self-powered all-solid-state rail potential limiting device is reset to sleep mode to continuously collect the rail potential amplitude.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) This invention achieves self-sufficient operation by combining wide voltage potential difference energy extraction with a hybrid energy storage architecture of supercapacitor and lithium thionyl chloride battery, completely eliminating the protection blind zone caused by external power interruption. At the same time, the all-solid-state thyristor assembly replaces the traditional mechanical switch, and the arc-free and wear-free switching design greatly improves the life of the device. Combined with the fully sealed potting and strong and weak current isolation physical structure, it effectively resists the harsh environment of high humidity, vibration and corrosion in tunnels, and reduces operation and maintenance costs.

[0020] (2) This invention also employs a time-frequency domain joint feature recognition algorithm. By calculating the voltage rise slope using the least squares method and the high-frequency energy ratio using FFT transformation, it accurately distinguishes between power frequency short-circuit faults, power frequency overvoltage faults, and lightning / operational overvoltage interference. This fundamentally solves the problem of malfunction caused by the single voltage threshold judgment of traditional devices. It ensures that the thyristor quickly conducts to form a leakage path under real fault conditions, realizing rapid clamping of rail potential. It can also lock the switch and recover surge energy during transient interference, reducing unnecessary interference to the traction power supply system and track circuit. In addition, the fault data storage and multi-mode communication functions of the device can also provide data support for the insulation coordination optimization of the traction power supply system, thereby improving the overall operational stability and intelligent protection level of the electrified rail transit traction return system.

[0021] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic cross-sectional view of the internal structure of the self-powered all-solid-state rail potential limiting device described in this embodiment of the invention.

[0024] Figure 2 This is a schematic diagram of the installation of the self-powered all-solid-state rail potential limiting device described in this embodiment of the invention;

[0025] Figure 3 This is a schematic diagram of train operation monitoring and electrical principles in an embodiment of the present invention;

[0026] Figure 4This is a schematic diagram of long-distance interval deployment within a tunnel in an embodiment of the present invention;

[0027] Figure 5 This is a circuit diagram of the self-powered module in an embodiment of the present invention;

[0028] Figure 6 This is a flowchart of the control method for the self-powered all-solid-state rail potential limiting device described in this embodiment of the invention.

[0029] The diagram shows: 1. Fully sealed protective shell; 2. Intelligent main control circuit board; 3. Low-voltage device insulation potting cavity; 4. Supercapacitor energy storage module; 5. Grounding lead-out wire; 6. Internal connection busbar; 7. Rail connection cable; 8. Rail; 9. High-efficiency heat sink; 10. High-power anti-parallel thyristor assembly; 11. High-voltage main circuit insulation cavity; 12. Strong and weak current isolation partition; 13. Isolation energy harvesting and drive interface unit; 14. Lithium thionyl chloride battery; 15. Wireless communication antenna; 16. Rail potential lead-in terminal; 17. Self-powered all-solid-state rail potential limiting device; 18. Concrete track slab; 19. Contact wire; 20. Tunnel. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] Example 1:

[0033] It should be noted that the device designed in this embodiment is suitable for long tunnel scenarios. Long tunnels differ from other application scenarios in that their complex terrain makes it difficult to lay a stable AC220V external power supply. Once the external auxiliary power supply is interrupted, the device will be completely paralyzed.

[0034] Meanwhile, long tunnels are susceptible to transient electromagnetic interference such as lightning surges and overhead contact line overvoltages. Traditional control logic relies solely on voltage amplitude judgments, lacking in-depth analysis of voltage waveform frequency, rate of change, and other characteristics, thus failing to effectively distinguish between transient lightning overvoltages and sustained power frequency short-circuit overvoltages. Furthermore, long tunnels also present harsh environments such as high humidity, condensation, acidic gases, and strong vibrations from train operation, for which traditional equipment lacks specific protective designs.

[0035] Secondly, traditional devices mostly employ a purely mechanical structure combining voltage relays and mechanical contactors, or a hybrid structure combining thyristors and contactors, both relying on mechanical contacts to connect and disconnect the rails from the ground. These mechanical contactors generate electric arcs when cutting off large currents, causing severe contact wear and a short service life. This fails to meet the maintenance-free and low-inspection requirements of long tunnels in remote sections. Frequent manual inspections and equipment replacements significantly increase the overall operating costs of the device throughout its lifecycle in long tunnels.

[0036] Therefore, this embodiment designs a self-powered, all-solid-state rail potential limiting device that integrates energy self-sufficiency, intelligent sensing, and rapid protection.

[0037] like Figure 1 and Figure 2 As shown, this embodiment provides a self-powered all-solid-state rail potential limiting device. The device includes a fully sealed protective housing 1 and a self-powered module, an all-solid-state switch module, an intelligent main control module, and an isolation drive and heat dissipation module housed within the fully sealed protective housing 1.

[0038] The device is electrically connected to the rail 8 via the rail connection cable 7, and connected to the integrated grounding grid via the grounding down conductor 5;

[0039] The isolation drive and heat dissipation module is disposed between the intelligent main control module and the all-solid-state switch module;

[0040] The intelligent main control module is electrically connected to the all-solid-state switch module, the self-powered module, and the isolation drive and heat dissipation module, respectively.

[0041] The self-powered module converts the potential difference signal collected by the isolation drive and heat dissipation module into DC power to power the intelligent main control module and the isolation drive and heat dissipation module.

[0042] In this embodiment, the device is fixed to the concrete base via a mounting bracket on the fully sealed protective housing 1, with the roadbed / track slab positioned sideways. It is then connected to the rail potential lead-in terminal 16, which is fixed to the side of the concrete track slab 18, via a low-impedance rail connection cable 7, thus achieving electrical connection with the rail 8. Simultaneously, it is connected to the tunnel integrated grounding network via the grounding down conductor 5 at the bottom of the self-powered all-solid-state rail potential limiting device 17.

[0043] like Figure 3 and Figure 4 As shown, when the train passes through tunnel 20, the overhead contact line 19 provides power to the train. Simultaneously, its operation indirectly causes rail potential fluctuations, triggering the device's normal energy harvesting / monitoring actions. Specifically, when the train enters tunnel 20, the pantograph contacts the overhead contact line 19 to harvest power. A strong traction current flows through the train, through the wheelsets, and into the rails 8, then back to the substation along the rails 8. That is, when the traction current flows in the rail circuit, due to the rail's own impedance and the tunnel's geological impedance, a potential difference (non-faulty) is formed between the rail and the ground. This is the energy source for the device's self-powered operation, charging the supercapacitor energy storage module 4 through the potential difference. Simultaneously, the device's all-solid-state switching module (thyristor) maintains a high-impedance, off-state state under correct conditions, preventing grounding of the rails. Therefore, it neither affects the traction power supply closed loop of the overhead contact line 19 nor interferes with the signal transmission of the track circuit. When the train exits the tunnel, the overhead contact line 19 stops supplying power to that section of the train, the rail traction return current disappears, and the potential difference drops. If the device has been fully charged, it returns to a low-power standby state (sleep mode), relying on the electrical energy stored in the supercapacitor (supercapacitor energy storage module 4) to maintain standby. Only when the supercapacitor is depleted will the lithium battery (lithium thionyl chloride battery 14) intervene to maintain the sleep mode of the intelligent main control module.

[0044] The self-powered module includes a full-wave rectifier unit, a wide-voltage input DC / DC converter unit, and a hybrid energy storage unit connected in sequence.

[0045] The hybrid energy storage unit includes a supercapacitor energy storage module 4 and a lithium thionyl chloride battery 14. The supercapacitor energy storage module 4 is connected to the power input terminal of the isolation drive and heat dissipation module and the power input terminal of the intelligent main control module, respectively. The lithium thionyl chloride battery 14 is connected to the power input terminal of the intelligent main control module through a reverse connection protection diode.

[0046] In this embodiment, the self-powered module abandons the single electromagnetic induction coil and adopts a hybrid energy storage unit composed of a wide-input-range potential difference energy harvesting circuit (including a full-wave rectification unit and a wide-voltage input DC / DC conversion unit), a supercapacitor (i.e., supercapacitor energy storage module 4), and a lithium battery (lithium thionyl chloride battery 14). This module is responsible for harvesting electrical energy from the potential difference between the rail 8 and the ground, and uses a hybrid energy storage energy management strategy to solve the energy maintenance problem in a long-term passive environment, realizing the device's self-powered operation. At the same time, a dual-power mutual exclusion switching architecture is used to switch the power supply to the intelligent main control module.

[0047] Understandably, the supercapacitor energy storage module 4 serves as the primary power supply, essentially the main power source for the device. Connected to the power input of the isolated drive and heat dissipation module, it provides the pulse current required to drive the all-solid-state switching module. Furthermore, the supercapacitor energy storage module 4 also powers the intelligent main control module. Utilizing its low internal resistance and high power density, the supercapacitor is responsible for providing a strong trigger pulse of up to several amperes to the gate of the high-power anti-parallel thyristor assembly 10 at the moment of fault triggering. This is the key energy source ensuring reliable conduction of the thyristor under low-temperature or aging conditions and establishing a discharge channel within microseconds.

[0048] Secondly, the lithium thionyl chloride battery 14 is a secondary power supply, which is actually the backup power supply of the device. It is connected to the power input terminal of the intelligent main control module through a reverse connection protection diode. When the voltage of the supercapacitor energy storage module 4 is too low, the lithium thionyl chloride battery 14 will automatically connect to maintain the dormant operation of the intelligent main control module.

[0049] Under normal operating conditions, when the supercapacitor voltage is sufficient, the reverse connection protection diode is reverse-biased and the lithium battery is in a zero-output state. However, under long-term vehicle-free conditions, when the supercapacitor is depleted due to prolonged vehicle inactivity, the reverse connection protection diode naturally conducts, and the lithium battery seamlessly takes over the power supply to the MCU of the intelligent main control module, maintaining the RTC clock and black box data storage with a microamp-level current to prevent the device from crashing.

[0050] If the device is in a low-power sleep state maintained by the lithium battery (at which point the supercapacitor is depleted and cannot drive the thyristor), and a short-circuit fault (voltage > 100V) suddenly occurs on rail 8, the device will perform the following transient energy replenishment action: the high voltage generated by the fault instantly replenishes the supercapacitor's charge within milliseconds through a potential difference energy extraction circuit composed of a full-wave rectifier unit and a wide-voltage input DC / DC converter unit. Since the MCU of the intelligent main control module has been pre-activated by the lithium battery, it does not need to undergo a lengthy power-on reset process. Once it detects that the supercapacitor voltage has risen back to the thyristor's minimum trigger threshold, the MCU immediately outputs a command to drive the thyristor to conduct using the fault energy just captured. This logic completely eliminates the protection blind spot of traditional passive devices during long-term power outage restarts.

[0051] like Figure 5 As shown, the full-wave rectifier unit is a single-phase bridge full-wave rectifier bridge composed of four fast recovery diodes;

[0052] Both AC input terminals of the full-wave rectifier unit are connected to the isolation drive and heat dissipation module to the rail 8 and the ground.

[0053] In this step, the two AC input terminals of the full-wave rectifier unit are actually connected to the isolated power extraction and drive interface unit 13 of the isolated drive and heat dissipation module, thereby connecting to the rail 8 and the ground.

[0054] The wide-voltage input DC / DC converter unit includes a polarized capacitor C1, a grounding capacitor C2, a flyback transformer T1, an NMOS transistor Q1, a diode D1, a Zener diode D2, a grounding resistor R1, a grounding resistor R2, and a resistor R. cs PWM controller U1 and optocoupler U2;

[0055] The positive terminal of the polarized capacitor C1 is connected to the first DC output terminal of the full-wave rectifier unit and one end of the primary winding of the flyback transformer T1, respectively; the negative terminal of the polarized capacitor C1 is connected to the second DC output terminal of the full-wave rectifier unit, the other end of the primary winding of the flyback transformer T1, and the drain of the NMOS transistor Q1, respectively.

[0056] In this step, the second DC output terminal of the full-wave rectifier unit is grounded.

[0057] The gate of the NMOS transistor Q1 is connected to the VCC terminal and the GATE terminal of the PWM controller U1, respectively; the source of the NMOS transistor Q1 is connected to the resistor R. cs One end is connected; the CS terminal of the PWM controller U1 is connected to resistor R respectively. cs The other end is connected to pin 1 of optocoupler U2; the FB terminal of PWM controller U1 is connected to primary ground; the GND terminal of PWM controller U1 and pin 2 of optocoupler U2 are connected to primary ground; pin 3 of optocoupler U2 is connected to grounding resistor R2 and the negative terminal of Zener diode D2 respectively; the negative terminal of supercapacitor energy storage module 4, the positive terminal of Zener diode D2 and pin 4 of optocoupler U2 are connected to secondary ground;

[0058] One end of the secondary winding of the flyback transformer T1 is connected to the positive terminal of diode D1; the negative terminal of diode D1 is connected to the grounding capacitor C2, the grounding resistor R1 and the positive terminal of the supercapacitor energy storage module 4 respectively; the other end of the secondary winding of the flyback transformer T1 is connected to the secondary ground.

[0059] In this embodiment, the full-wave rectifier unit and the wide-voltage input DC / DC converter unit together constitute a potential difference energy harvesting circuit, which is integrated with the intelligent main control module on the intelligent main control circuit board 2. Figure 5 In the diagram, DC Input (+) represents the positive input terminal of the wide-voltage input DC / DC converter unit, DC Input (-) represents the negative input terminal of the wide-voltage input DC / DC converter unit, DC Output (+) represents the positive output terminal of the wide-voltage input DC / DC converter unit, and DC Output (-) represents the negative output terminal of the wide-voltage input DC / DC converter unit.

[0060] The device utilizes the isolated power extraction and drive interface unit 13, which bridges the steel rail 8 and the ground, to acquire a potential difference signal. This signal first passes through a full-wave rectifier bridge composed of four fast recovery diodes, converting the AC or DC potential, which has uncertain polarity and fluctuates significantly (e.g., 10V~150V), into a unidirectional pulsating DC current. Then, this DC current enters the DC / DC converter (composed of a flyback transformer T1, a PWM controller U1, and an NMOS transistor Q1) of the wide-voltage input DC / DC converter unit. Through high-frequency switching modulation, the unstable high-voltage input is converted into a stable DC current (e.g., 5V / 12V), which preferentially charges the supercapacitor energy storage module 4. The optocoupler U2 acts in the isolated feedback voltage regulation stage, converting the voltage state of the charging supercapacitor on the right into an optical signal, which is then transmitted in isolation to the PWM controller U1 on the left. This ensures both physical isolation between strong and weak currents and allows the device to determine when to stop charging. Specifically, the circuit collects the voltage across the supercapacitor. Once the voltage reaches the target value, it drives the optocoupler U2 to emit light, notifying the NMOS transistor Q1 to stop working and preventing the supercapacitor from exploding due to overvoltage.

[0061] The all-solid-state switch module includes a high-power anti-parallel thyristor assembly 10 and a high-efficiency heat sink 9. The high-power anti-parallel thyristor assembly 10 is mounted in close contact with the high-efficiency heat sink 9, and one end of the high-efficiency heat sink 9 extends to the outside of the fully sealed protective housing 1 for heat dissipation.

[0062] The interior of the fully sealed protective housing 1 is divided into a high-voltage main circuit insulation cavity 11 and a low-voltage device insulation potting cavity 3 by a strong and weak current isolation partition 12. The hybrid energy storage unit of the self-powered module and the intelligent main control module are encapsulated in the insulating potting glue inside the low-voltage device insulation potting cavity 3.

[0063] In this embodiment, the all-solid-state switch module serves as the main circuit actuator, connected in parallel between the rail 8 and the ground. It is controlled by the intelligent main control module to achieve the switching of the rail 8 and the ground. By replacing the traditional mechanical contactor with the all-solid-state switch module, rapid switching without arcing or wear can be achieved. Simultaneously, the self-powered module and the intelligent main control module are encapsulated in insulating potting compound, preventing moisture corrosion and mechanical vibration in the tunnel environment.

[0064] The isolated drive and heat dissipation module includes an isolated power harvesting and drive interface unit 13;

[0065] The high-potential side of the isolation power harvesting and drive interface unit 13 is connected to the rail connection cable 7 via the internal connection bus 6.

[0066] The zero-potential side of the isolation power extraction and drive interface unit 13 is connected to the grounding busbar inside the fully sealed protective housing 1, and the grounding busbar is electrically connected to the grounding lead-down wire 5 that passes through the fully sealed protective housing 1.

[0067] The isolated power harvesting and drive interface unit 13 is connected to the input terminal of the self-powered module and the intelligent main control module, respectively.

[0068] In this embodiment, the isolation drive and heat dissipation module also includes a strong and weak current isolation optocoupler, a gate drive circuit, a high-efficiency heat sink, and a fully sealed potting protective shell designed for the high humidity environment of tunnels.

[0069] In this embodiment, the intelligent main control module mainly includes a low-power MCU / DSP processor, a high-frequency A / D sampling unit, an FFT operation unit, a large-capacity non-volatile memory (black box), and a multi-modal communication unit. The multi-modal communication unit integrates wired and wireless transmission interfaces that serve as backups for each other, including a wired interface (RS-485 / fiber optic) for accessing the tunnel monitoring network, and a wireless unit (LoRa / NB-IoT) for low-power wide-area transmission and a Wi-Fi / Bluetooth unit for near-field maintenance. The multi-modal communication unit is also connected to the wireless communication antenna 15. The multi-modal communication unit is configured to upload fault characteristic parameters via the wireless communication antenna 15 or a wired network after the device is reset.

[0070] Understandably, existing technologies largely rely on single inductive energy harvesting, which is prone to energy interruption under prolonged periods of no vehicle operation or weak return current conditions. This embodiment effectively improves the device's adaptability to passive environments by constructing a power supply architecture that combines wide-voltage potential difference energy harvesting with hybrid energy storage. On the one hand, utilizing potential difference energy harvesting technology broadens the voltage range for energy acquisition by the device; on the other hand, introducing a long-life primary lithium battery as a backup power source effectively alleviates the difficulty of cold-starting after long-term shutdowns caused by supercapacitor self-discharge, which helps maintain the continuity of the RTC clock and critical log data, thereby reducing the risk of protection blind spots caused by power outages.

[0071] Secondly, considering the environmental characteristics of long tunnels, such as high humidity, condensation, and train vibration, this embodiment employs an integral potting process and a vibration-resistant mounting structure. This design provides effective physical isolation for the internal circuitry and energy storage unit, reducing the corrosive effects of moisture and acidic gases on component leads. Simultaneously, the cured potting layer enhances the mechanical strength of the components, reducing the risk of desoldering or poor contact due to long-term vibration, thereby extending the device's maintenance cycle and improving its operational reliability in hard-to-reach areas.

[0072] This embodiment also utilizes a high-power anti-parallel thyristor assembly 10 in conjunction with a supercapacitor energy storage module 4, resulting in superior action response characteristics compared to traditional mechanical contactors. The high-power discharge characteristics of the supercapacitor facilitate the provision of sufficient gate drive current in low-temperature environments, enabling the thyristors to conduct rapidly. This allows the device to establish a discharge path more quickly and limit the overvoltage amplitude when faced with near-end short circuits causing a sharp rise in rail potential, providing more timely protection for signal equipment along the line.

[0073] Example 2:

[0074] See Figure 6 The figure shows that the method includes steps S1, S2, S3, S4, S5 and S6.

[0075] Step S1: The potential difference signal between the rail and the ground is collected in real time by a self-powered all-solid-state rail potential limiting device to obtain the rail potential amplitude;

[0076] In this step, the potential difference signal is input into the full-wave rectification unit of the self-powered module. The rail potential difference signal with uncertain polarity and large amplitude fluctuation (from a few volts to hundreds of volts) is processed by full-wave rectification to convert it into a unidirectional pulsating DC signal, eliminating the influence of signal polarity, and obtaining a positive DC sampling signal with the same value as the original rail potential amplitude, i.e., the rail potential amplitude.

[0077] Step S2: Switch the operating mode of the self-powered all-solid-state rail potential limiting device according to the rail potential amplitude. The operating modes include sleep mode and full-speed operation mode.

[0078] Step S3: If it is in sleep mode, execute the hybrid energy storage energy management strategy based on wide voltage potential difference to maintain low power consumption and continuously collect the rail potential amplitude.

[0079] In this step, the hibernation mode is the normal standby state of the device and the main operating mode under fault-free conditions. The goal is to minimize energy consumption, continuously extract and store energy, maintain basic monitoring, ensure that the device does not crash under long-term no-vehicle / weak rail potential conditions, and can quickly respond to sudden faults, that is, the rail potential amplitude has not reached the preset wake-up threshold, there is no overvoltage / fault trigger signal, and it is the normal train operation condition.

[0080] In sleep mode, the intelligent main control module retains only the microampere-level wake-up circuit and RTC clock, shutting down all high-power peripherals such as high-frequency A / D sampling, FFT calculation, and wireless communication, and the MCU enters deep sleep mode. Meanwhile, the self-powered module remains operational, implementing a hybrid energy management strategy that utilizes a wide voltage potential difference for energy extraction. It continuously collects the weak potential difference between the rail 8 and the ground, and after rectification and power conversion, prioritizes charging the supercapacitor. Only when the supercapacitor (i.e., supercapacitor energy storage module 4) is depleted and the rail has no potential is the backup battery (i.e., lithium thionyl chloride battery 14) supplying power with a microampere-level current. Simultaneously, it retains low-frequency, low-power acquisition of the rail potential amplitude, eliminating the need for high-speed discrete sampling. Once the rail potential amplitude is detected to exceed the preset wake-up threshold, mode switching is immediately triggered.

[0081] By employing a hybrid energy storage management strategy with a hibernation mode, the device can achieve long-term self-sufficiency and standby, avoiding dependence on external power sources and eliminating protection blind spots caused by power outages, thus providing a foundation for rapid device wake-up.

[0082] In step S3, the execution of the hybrid energy storage energy management strategy based on wide voltage potential difference energy extraction includes:

[0083] Step S31: Perform full-wave rectification processing on the real-time acquired potential difference signal to obtain a unidirectional pulsating DC voltage with the same amplitude as the rail potential.

[0084] Step S32: With the goal of maximizing the utilization rate of weak energy, the unidirectional pulsating DC voltage is converted using the maximum power point tracking strategy to obtain a conversion voltage that is stable at the system's standard operating voltage and the corresponding rail conversion energy.

[0085] In this step, in addition to using the maximum power point tracking strategy, adaptive duty cycle adjustment can also be used to stabilize the conversion voltage at the system's standard operating voltage (e.g., 5V / 12V).

[0086] Step S33: Obtain the current terminal voltage of the supercapacitor in the self-powered all-solid-state rail potential limiting device;

[0087] Step S34: Perform hybrid energy storage charging control and power supply circuit switching based on the current terminal voltage and the conversion voltage.

[0088] In this step, a supercapacitor priority charging and discharging mechanism and a seamless switching logic for the backup battery are set up. As the main energy storage unit, the supercapacitor undertakes more than 99% of the system's energy throughput. It can quickly absorb the fluctuating potential energy of the rail and can also instantly release a large current to drive the thyristors (i.e., the high-power anti-parallel thyristor assembly 10) in the event of a fault.

[0089] Step S34 includes:

[0090] Step S341: If the conversion voltage is greater than the current terminal voltage and the current terminal voltage is less than the charging cutoff voltage, the supercapacitor is charged using the energy converted from the rail until the current terminal voltage reaches the charging cutoff voltage, at which point the charging circuit is cut off.

[0091] In this step, during charging, the conversion voltage must be greater than the current terminal voltage (i.e., there is a charging voltage difference, and energy can flow from the rail side to the supercapacitor) and the current terminal voltage must be less than the charging cut-off voltage (leaving a safety margin). Therefore, precise charging control of the supercapacitor is achieved.

[0092] Step S342: If the current terminal voltage of the supercapacitor is not lower than the system survival threshold or the rail potential amplitude is greater than zero, then the supercapacitor is used to provide low-power power to the intelligent main control module of the self-powered all-solid-state rail potential limiting device.

[0093] In this step, this state is the normal state of the device in hibernation mode. The device prioritizes consuming environmentally captured energy throughout the process. Whether there is energy input from the rail (train passing by, potential fluctuations) or no energy from the rail but sufficient power in the supercapacitor, the device is powered by the supercapacitor, and the backup battery is always in a disconnected zero-output state.

[0094] Step S343: If the current terminal voltage of the supercapacitor is lower than the system survival threshold and the rail potential amplitude is zero, then the backup battery is used to provide low-power power supply to the intelligent main control module.

[0095] In this step, it is necessary to simultaneously meet the following conditions: the current terminal voltage of the supercapacitor is lower than the system survival threshold (i.e., the supercapacitor has insufficient power to supply electricity) and the rail potential amplitude is zero (there is no potential energy on the rail side, and it is impossible to replenish energy through the self-powered module, such as when there are no vehicles for a long time or when the line is under maintenance). When this condition is met, the MCU achieves seamless conduction of the backup battery through the anti-reverse connection diode and electronic switch. The lithium battery supplies power to the core sleep circuit of the intelligent main control module with a microamplitude current, maintaining only the RTC clock and the wake-up circuit, while all other peripherals are turned off, minimizing power consumption.

[0096] Step S4: If it is in full-speed operation mode, the rail potential signal is sampled at high speed to obtain voltage time series data;

[0097] In this step, the full-speed operation mode is the fault detection and response state of the device. The goal is to acquire signals at high speed, accurately identify faults, and quickly execute protection actions. It is the core mode for the device to perform rail potential limiting protection function. It is only triggered when the rail potential reaches the preset wake-up threshold and is immediately reset to sleep mode after the fault is handled.

[0098] In full-speed operation mode, the intelligent main control module wakes up all peripherals, the high-frequency A / D converter starts at full speed (to achieve high-speed discretization sampling of rail potential signals), the FFT operation unit and data processing unit work synchronously, the isolation drive and heat dissipation module enter standby mode, and the self-powered module performs energy recovery / pulse release and other operations according to the working conditions.

[0099] Step S5: Perform joint feature identification in the time and frequency domain and rail fault judgment through the voltage time series data to obtain fault identification results. The fault identification results include power frequency short circuit faults, power frequency overvoltage faults, and lightning interference / operational overvoltage conditions.

[0100] Step S5 includes:

[0101] Step S51: Perform sliding window truncation on the voltage time series data to obtain sampling window data of a preset length, wherein the sampling window data is an ordered set of voltage sampling points;

[0102] In this step, the set of ordered voltage sampling points is the sampling time. and the corresponding voltage sample value Composition, in which, Indicates the first The time of each sampling point Indicates the first Voltage values ​​at each sampling point.

[0103] Step S52: Perform linear fitting on the sampling window data using the least squares method to calculate the voltage rise slope;

[0104] In this step, the equation of the straight line is obtained through fitting. ,in, Indicates voltage. Indicates the slope. Indicates time, This represents the intercept.

[0105] According to the least squares principle, the formula for calculating the slope that minimizes the sum of squared errors is:

[0106] ;

[0107] In the formula, Indicates the slope. Indicates the length of the sliding window. Indicates the first The time of each sampling point Indicates the first Voltage values ​​at each sampling point.

[0108] To simplify the calculations, let the sampling interval be constant. Simplified to sequence index The formula for calculating the slope is simplified to a discrete form, yielding the final voltage rise slope:

[0109] ;

[0110] In the formula, Indicates the slope of voltage rise. Indicates the sampling interval. Indicates the length of the sliding window. Represents a sequence index. Indicates the first Voltage values ​​at each sampling point.

[0111] Step S53: If the voltage rise slope exceeds the preset fast-acting threshold, it is determined to be a power frequency short circuit fault;

[0112] In this step, if the voltage rise slope exceeds the preset speed threshold, the voltage will show a step-like upward trend (characteristics consistent with near-end short circuit), and it will be determined as a power frequency short circuit fault.

[0113] Step S54: If the voltage rise slope does not exceed the preset speed threshold, perform a fast Fourier transform on the sampling window data to convert the time-domain voltage time series data into a frequency domain signal, and calculate the proportion of high-frequency energy in the frequency domain signal.

[0114] In this step, to distinguish between power frequency overvoltage faults and lightning interference / switching overvoltage conditions, the high-frequency energy percentage is constructed:

[0115] ;

[0116] In the formula, Indicates the proportion of high-frequency energy. Indicates the length of the sliding window. This indicates the sequence number corresponding to the high-frequency cutoff frequency. Represents frequency domain signals, This indicates the sequence number of the frequency point in the frequency domain after the FFT transform. This indicates a modulo operation.

[0117] Step S55: If the proportion of high-frequency energy exceeds the preset interference threshold, it is determined to be a lightning interference / operational overvoltage condition.

[0118] In this step, the preset interference threshold can be set to 30%.

[0119] Step S56: If the proportion of high-frequency energy does not exceed the preset interference threshold and the rail potential amplitude exceeds the preset safety limit, it is determined to be a power frequency overvoltage fault.

[0120] Step S6: Based on the fault identification result, execute the corresponding fault handling action, and reset the self-powered all-solid-state rail potential limiting device to sleep mode to continuously collect the rail potential amplitude.

[0121] Step S6 includes:

[0122] Step S61: If the fault identification result is a power frequency short circuit fault or a power frequency overvoltage fault, control the supercapacitor to release a strong trigger pulse, which is amplified and drives the thyristor to conduct, so that a low impedance leakage path is formed between the rail and the ground.

[0123] In this step, if a power frequency short circuit or overvoltage fault exists, which is a real fault condition, the MCU instructs the supercapacitor energy storage module 4 to instantly release energy, outputting a strong trigger pulse of up to several amperes. This pulse drives the high-power anti-parallel thyristor assembly 10 to conduct via the isolation power extraction and drive interface unit 13, making the device instantly become a low-impedance channel, directly grounding the rail 8, thereby forcibly clamping the dangerous potential within a safe range (e.g., residual voltage <10V).

[0124] Step S62: After the thyristor is turned on, the main circuit current and the residual voltage at the rail port are collected in real time;

[0125] Step S63: When the main circuit current is less than the thyristor's holding current and the residual voltage at the rail port is lower than the safety voltage within a preset time, it is determined that the fault has been restored to normal, the strong trigger pulse is stopped, and the thyristor is turned off naturally when the current crosses zero.

[0126] In this step, after the thyristor is turned on, the device enters the hysteresis monitoring stage, continuously monitoring the fault current (main circuit current) flowing through the internal connecting bus 6 and the residual voltage at the rail port. Only when the fault current decays below the holding current, and the residual voltage at the rail port is stably lower than the safety reset voltage (e.g., 50V) for a preset time (e.g., 5s), does the system determine that the fault source has been cleared. At this time, no strong trigger pulse is sent, the thyristor naturally turns off at the current zero-crossing point, and the device automatically resets the state machine and returns to the low-power mode.

[0127] Step S64: If the fault identification result is lightning interference / operational overvoltage condition, control the thyristor to remain off and perform a blocking operation, and recover energy from the transient high voltage pulse until the rail potential amplitude returns to the normal threshold.

[0128] In this step, when the high-frequency voltage sensor in the isolation power extraction and drive interface unit 13 detects a sharp voltage spike within microseconds, the MCU chip on the intelligent main control circuit board 2 is instantly awakened. Analysis using the FFT algorithm reveals an extremely sharp waveform with energy concentrated in the high-frequency band, indicating a transient interference rather than a persistent fault. Specifically, in the case of lightning interference / operational overvoltage, the MCU immediately issues a lockout command. Despite the high voltage, the high-power anti-parallel thyristor assembly 10 remains off, preventing false turn-on. This not only avoids the risk of short-circuiting the signal system due to lightning strikes, but also allows the potential difference power extraction circuit to utilize this transient high-voltage pulse. After rectification and clamping, the pulse is rapidly charged into the supercapacitor energy storage module 4, achieving energy recovery and reducing the absorption burden on the preceding varistor.

[0129] Step S65: After the fault is restored to normal, upload the fault data and reset to sleep mode to continuously collect the rail potential amplitude.

[0130] Step S65 includes:

[0131] Step S651: After the fault is restored to normal, the fault characteristic information is uploaded to the monitoring terminal through the self-powered all-solid-state rail potential limiting device;

[0132] Step S652: Store the voltage waveform data before and after the fault in the local non-volatile memory of the self-powered all-solid-state rail potential limiting device;

[0133] Step S653: Clear the temporary buffer in the self-powered all-solid-state rail potential limiting device, reset the full-speed operation mode to sleep mode, and continuously collect the potential difference signal between the rail and the ground to obtain the rail potential amplitude.

[0134] In this embodiment, to address the issue of traditional voltage protection devices being susceptible to malfunction due to transient lightning strikes, a time-frequency domain joint feature recognition algorithm is employed. This algorithm combines FFT spectrum analysis with voltage change rate trend prediction to more accurately distinguish between high-frequency lightning intrusion waves and short-circuit overvoltages primarily characterized by power frequency. This multi-dimensional discrimination logic helps to suppress non-faulty lightning false triggering while ensuring rapid response to real faults, thereby reducing unnecessary interference to the traction power supply system and track circuit signals. Furthermore, under non-faulty operating conditions during normal train operation, the application of a low-power energy harvesting circuit makes it possible for the device to achieve self-sustaining energy in tunnel environments without external power sources.

[0135] Therefore, the intelligent analysis and hierarchical control mechanism set in the device provides a feasible technical path for solving the rail potential limitation problem in the complex electromagnetic environment of long tunnels, and improves the operational stability of the rail transit power supply system to a certain extent.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0137] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A self-powered, all-solid-state rail potential limiting device, characterized in that, The device includes a fully sealed protective housing (1) and a self-powered module, a solid-state switch module, an intelligent main control module and an isolated drive and heat dissipation module housed within the fully sealed protective housing (1); The device is electrically connected to the rail (8) via a rail connection cable (7), and the device is connected to the integrated grounding grid via a grounding down conductor (5); The isolation drive and heat dissipation module is disposed between the intelligent main control module and the all-solid-state switch module; The intelligent main control module is electrically connected to the all-solid-state switch module, the self-powered module, and the isolation drive and heat dissipation module, respectively. The self-powered module converts the potential difference signal collected by the isolation drive and heat dissipation module into DC power to power the intelligent main control module and the isolation drive and heat dissipation module.

2. The self-powered all-solid-state rail potential limiting device according to claim 1, characterized in that, The self-powered module includes a full-wave rectifier unit, a wide-voltage input DC / DC converter unit, and a hybrid energy storage unit connected in sequence. The hybrid energy storage unit includes a supercapacitor energy storage module (4) and a lithium thionyl chloride battery (14). The supercapacitor energy storage module (4) is connected to the power input terminal of the isolation drive and heat dissipation module and the power input terminal of the intelligent main control module, respectively. The lithium thionyl chloride battery (14) is connected to the power input terminal of the intelligent main control module through a reverse connection protection diode.

3. The self-powered all-solid-state rail potential limiting device according to claim 2, characterized in that, The full-wave rectifier unit is a single-phase bridge full-wave rectifier bridge composed of four fast recovery diodes; Both AC input terminals of the full-wave rectifier unit are connected to the isolation drive and heat dissipation module to the rail (8) and the ground; The wide-voltage input DC / DC converter unit includes a polarized capacitor C1, a grounding capacitor C2, a flyback transformer T1, an NMOS transistor Q1, a diode D1, a Zener diode D2, a grounding resistor R1, a grounding resistor R2, and a resistor R. cs PWM controller U1 and optocoupler U2; The positive terminal of the polarized capacitor C1 is connected to the first DC output terminal of the full-wave rectifier unit and one end of the primary winding of the flyback transformer T1, respectively; the negative terminal of the polarized capacitor C1 is connected to the second DC output terminal of the full-wave rectifier unit, the other end of the primary winding of the flyback transformer T1, and the drain of the NMOS transistor Q1, respectively. The gate of the NMOS transistor Q1 is connected to the VCC terminal and the GATE terminal of the PWM controller U1, respectively; the source of the NMOS transistor Q1 is connected to the resistor R. cs One end is connected; the CS terminal of the PWM controller U1 is connected to resistor R respectively. cs The other end is connected to the first pin of the optocoupler U2; the FB terminal of the PWM controller U1 is connected to the primary ground; the GND terminal of the PWM controller U1 and the second pin of the optocoupler U2 are connected to the primary ground; the third pin of the optocoupler U2 is connected to the grounding resistor R2 and the negative terminal of the Zener diode D2 respectively; the negative terminal of the supercapacitor energy storage module (4), the positive terminal of the Zener diode D2 and the fourth pin of the optocoupler U2 are connected to the secondary ground; One end of the secondary winding of the flyback transformer T1 is connected to the positive terminal of the diode D1; the negative terminal of the diode D1 is connected to the grounding capacitor C2, the grounding resistor R1 and the positive terminal of the supercapacitor energy storage module (4); the other end of the secondary winding of the flyback transformer T1 is connected to the secondary ground.

4. The self-powered all-solid-state rail potential limiting device according to claim 1, characterized in that, The all-solid-state switch module includes a high-power anti-parallel thyristor assembly (10) and a high-efficiency heat sink (9). The high-power anti-parallel thyristor assembly (10) is mounted in close contact with the high-efficiency heat sink (9), and one end of the high-efficiency heat sink (9) extends to the outside of the fully sealed protective shell (1) for heat dissipation. The interior of the fully sealed protective shell (1) is divided into a high-voltage main circuit insulation cavity (11) and a low-voltage device insulation potting cavity (3) by a strong and weak current isolation partition (12). The hybrid energy storage unit of the self-powered module and the intelligent main control module are encapsulated in the insulating potting glue inside the low-voltage device insulation potting cavity (3).

5. The self-powered all-solid-state rail potential limiting device according to claim 1, characterized in that, The isolated drive and heat dissipation module includes an isolated power harvesting and drive interface unit (13). The high-potential side of the isolation power harvesting and drive interface unit (13) is connected to the rail connection cable (7) through the internal connection bus (6); The zero potential side of the isolation power extraction and drive interface unit (13) is connected to the grounding busbar inside the fully sealed protective housing (1), and the grounding busbar is electrically connected to the grounding lead-down wire (5) that passes through the fully sealed protective housing (1). The isolated power harvesting and drive interface unit (13) is connected to the input terminal of the self-powered module and the intelligent main control module, respectively.

6. A control method for a self-powered all-solid-state rail potential limiting device, applied to the self-powered all-solid-state rail potential limiting device according to any one of claims 1 to 5, characterized in that, include: The potential difference signal between the rail and the ground is collected in real time by a self-powered all-solid-state rail potential limiting device to obtain the rail potential amplitude; The operating mode of the self-powered all-solid-state rail potential limiting device is switched according to the rail potential amplitude. The operating modes include a sleep mode and a full-speed operating mode. If in sleep mode, a hybrid energy management strategy based on wide voltage potential difference is implemented to maintain low power consumption and continuously collect rail potential amplitude. If it is in full-speed operation mode, the rail potential signal is sampled at high speed to obtain voltage time series data; By performing joint feature identification in the time and frequency domains and judging rail faults using the voltage time series data, fault identification results are obtained. The fault identification results include power frequency short circuit faults, power frequency overvoltage faults, and lightning interference / operational overvoltage conditions. Based on the fault identification results, the corresponding fault handling actions are executed, and the self-powered all-solid-state rail potential limiting device is reset to sleep mode to continuously collect the rail potential amplitude.

7. The control method for the self-powered all-solid-state rail potential limiting device according to claim 6, characterized in that, The implementation of the hybrid energy storage energy management strategy based on wide voltage potential difference energy extraction includes: The potential difference signal acquired in real time is subjected to full-wave rectification to obtain a unidirectional pulsating DC voltage with the same amplitude as the rail potential. With the goal of maximizing the utilization rate of weak energy, a maximum power point tracking strategy is used to convert the unidirectional pulsating DC voltage to obtain a conversion voltage that is stable at the system's standard operating voltage and the corresponding rail conversion energy. Obtain the current terminal voltage of the supercapacitor in the self-powered all-solid-state rail potential limiting device; Hybrid energy storage charging control and power supply circuit switching are achieved through the current terminal voltage and the conversion voltage.

8. The control method for the self-powered all-solid-state rail potential limiting device according to claim 7, characterized in that, The method of controlling hybrid energy storage charging and switching power supply circuits using the current terminal voltage and the conversion voltage includes: If the conversion voltage is greater than the current terminal voltage and the current terminal voltage is less than the charging cutoff voltage, the supercapacitor is charged using the energy converted from the rail until the current terminal voltage reaches the charging cutoff voltage, at which point the charging circuit is cut off. If the current terminal voltage of the supercapacitor is not lower than the system survival threshold or the rail potential amplitude is greater than zero, the supercapacitor is used to provide low-power power to the intelligent main control module of the self-powered all-solid-state rail potential limiting device. If the current terminal voltage of the supercapacitor is lower than the system survival threshold and the rail potential amplitude is zero, then a backup battery is used to provide low-power power to the intelligent main control module.

9. The control method for the self-powered all-solid-state rail potential limiting device according to claim 6, characterized in that, The process of performing joint time-frequency domain feature recognition and rail fault judgment using the voltage time series data to obtain fault identification results includes: A sliding window is used to extract voltage time series data to obtain sampling window data of a preset length, wherein the sampling window data is an ordered set of voltage sampling points; The least squares method was used to perform linear fitting on the sampling window data to calculate the voltage rise slope. If the voltage rise slope exceeds the preset speed threshold, it is determined to be a power frequency short circuit fault. If the voltage rise slope does not exceed the preset speed threshold, a fast Fourier transform is performed on the sampling window data to convert the time-domain voltage time series data into a frequency domain signal, and the proportion of high-frequency energy in the frequency domain signal is calculated. If the proportion of high-frequency energy exceeds the preset interference threshold, it is determined to be a lightning interference / operational overvoltage condition. If the proportion of high-frequency energy does not exceed the preset interference threshold and the rail potential amplitude exceeds the preset safety limit, it is determined to be a power frequency overvoltage fault.

10. The control method for the self-powered all-solid-state rail potential limiting device according to claim 6, characterized in that, The process involves executing corresponding fault handling actions based on the fault identification results, resetting the self-powered all-solid-state rail potential limiting device to sleep mode, and continuously collecting rail potential amplitude, including: If the fault identification result is a power frequency short circuit fault or a power frequency overvoltage fault, the supercapacitor is controlled to release a strong trigger pulse, which is amplified and drives the thyristor to conduct, so that a low impedance leakage path is formed between the rail and the ground. After the thyristor is turned on, the main circuit current and the residual voltage at the rail port are collected in real time. If the main circuit current is less than the thyristor's holding current and the residual voltage at the rail port is lower than the safe voltage within a preset time, it is determined that the fault has been restored to normal, the strong trigger pulse is stopped, and the thyristor is turned off naturally when the current crosses zero. If the fault identification result is lightning interference / operational overvoltage condition, the control thyristor is kept off and a blocking operation is performed, and energy is recovered from the transient high voltage pulse until the rail potential amplitude returns to the normal threshold. Once the fault is resolved, the fault data will be uploaded and the system will be reset to sleep mode to continuously collect the rail potential amplitude.

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