Surge protection circuit and underwater medium voltage conversion power supply

Abstract

The application relates to the technical field of underwater power supply, and provides a surge protection circuit and an underwater medium-voltage conversion power supply, which comprise a protection subcircuit and a reset subcircuit arranged in parallel. The protection subcircuit is arranged between a power supply end and a subsequent circuit, and the protection subcircuit is connected in parallel with the subsequent circuit. The protection subcircuit comprises at least one protection device, which is used for turning on the protection subcircuit to short-circuit the subsequent circuit when the change rate of input voltage of the power supply end is greater than a preset threshold value and the input voltage is greater than a first breakdown voltage. The reset subcircuit is arranged between the protection subcircuit and the subsequent circuit, and is used for closing the circuit to reset the protection subcircuit after the protection subcircuit is turned on. Based on the scheme provided in the embodiment, the protection subcircuit is rapidly turned on when a transient high-voltage impact is detected, the surge current is discharged, the reset subcircuit automatically cuts off the protection path after the surge ends, the normal power supply of the system is restored, and the operation reliability and self-recovery ability of the medium-voltage conversion power supply in a complex marine environment are improved.

Description

Technical Field

[0001] This application relates to the field of underwater power supply technology, and in particular to a surge protection circuit and an underwater medium-voltage conversion power supply. Background Technology

[0002] A submarine observation network refers to a platform that installs various scientific instruments on the seabed to conduct long-term, dynamic, and real-time observations of the seawater layer and ocean floor. The power supply system of the submarine observation network includes a shore-based power supply (PFE) and an underwater observation medium voltage converter (OMVC). Due to the complex seabed environment, submarine cables may experience surge currents that impact the power supply system due to factors such as fishing operations, earthquakes, lightning, power grid switching, equipment start-up and shutdown, reef abrasion, and fish bites.

[0003] To prevent damage to the OMVC due to high inrush current, surge protection circuits need to be designed inside the OMVC to ensure that the inrush current generated in the power supply system does not affect the subsequent circuits of the OMVC, thereby minimizing the impact of inrush current on communication and maintenance costs.

[0004] However, due to the characteristic that the operating voltage of OMVC varies with the output power, conventional surge protection circuits cannot adapt to surge protection tasks in various voltage scenarios, resulting in poor protection effect on downstream circuits, and consequently, low stability and reliability of the power supply system for the submarine observation network. Summary of the Invention

[0005] This application provides a surge protection circuit and an underwater medium-voltage conversion power supply to solve the problem of low power supply stability and reliability of underwater power supply equipment caused by surge current.

[0006] In a first aspect, embodiments of this application provide a surge protection circuit applied to an underwater medium-voltage conversion power supply. The underwater medium-voltage conversion power supply includes a power supply terminal and a subsequent circuit. The surge protection circuit includes a protection sub-circuit and a reset sub-circuit, wherein: the protection sub-circuit is disposed between the power supply terminal and the subsequent circuit, and the protection sub-circuit is connected in parallel with the subsequent circuit; the protection sub-circuit includes at least one protection device, and the protection sub-circuit is configured to conduct when the rate of change of the input voltage at the power supply terminal is greater than a preset threshold and the input voltage is greater than a first breakdown voltage of the protection sub-circuit, so as to short-circuit the subsequent circuit; the reset sub-circuit is disposed between the protection sub-circuit and the subsequent circuit, and the reset sub-circuit is connected in parallel with the protection sub-circuit, and the reset sub-circuit is configured to close the circuit to reset the protection sub-circuit after the protection sub-circuit is turned on.

[0007] Based on the solution provided in this embodiment, precise protection against surge currents under different operating voltage scenarios is achieved by dynamically responding to the rate and amplitude of input voltage changes, effectively avoiding the poor adaptability problem caused by the fixed breakdown voltage in traditional solutions. The protection sub-circuit quickly conducts upon detecting a transient high-voltage surge, discharging the surge current and preventing overvoltage damage to subsequent circuits. Simultaneously, the reset sub-circuit automatically disconnects the protection path after the surge ends, restoring normal system power supply. The entire process requires no manual intervention, improving the operational reliability and self-healing capability of the medium-voltage converter in complex marine environments.

[0008] In one feasible implementation, the protective device is a gas discharge tube (GDT). The GDT has a second breakdown voltage and is configured to conduct when the rate of change of the voltage across the GDT exceeds a preset threshold and the voltage value across the GDT is greater than the second breakdown voltage. The value of the first breakdown voltage is the same as the sum of the second breakdown voltages of the GDT in the protective sub-circuit. Thus, when the input voltage instantaneously increases and the rate of change exceeds the set threshold, the GDT quickly breaks down and conducts, dissipating the surge energy, thereby clamping the voltage, protecting the subsequent circuits, and effectively suppressing the impact of high-voltage pulses on the medium-voltage conversion power supply. Simultaneously, the reset sub-circuit conducts after the surge event ends, disconnecting the power supply to the path containing the GDT, allowing the GDT to return to a high-impedance state, ensuring a continuous and stable power supply to the system.

[0009] In one feasible implementation, the GDT includes two pins and two electrodes, with a preset spacing between the two electrodes. One end of each pin is electrically connected to one electrode, and the other end of the pin is electrically connected to the corresponding line of the protection sub-circuit. This preset spacing between the electrodes provides the GDT with stable breakdown voltage characteristics, ensuring that it is not broken down within a set voltage threshold range. Simultaneously, when a transient high voltage occurs, the gas between the electrodes rapidly ionizes to form a conductive path, achieving a fast response and suppressing the propagation of the high-voltage pulse.

[0010] In one feasible implementation, the protection subcircuit further includes at least one capacitor. When the protection subcircuit includes at least two GDTs, one end of the capacitor is positioned between two adjacent GDTs, and the other end of the capacitor is electrically connected to the power supply terminal. This reduces the breakdown voltage of the protection subcircuit after at least two GDTs are connected in series when a surge current occurs. In this way, the capacitor can provide a transient low-impedance path when a surge current occurs, avoiding the problem of protection failure due to the surge current failing to trigger multiple GDTs to conduct simultaneously. Through the synergistic effect of voltage division and energy storage, the response consistency of the protection subcircuit is improved.

[0011] In one feasible implementation, the protection subcircuit includes six gas-diverter (GDT) circuits connected in series, each GDT connected in parallel with the reset subcircuit and subsequent circuits. The protection subcircuit also includes two capacitors connected in parallel, each capacitor being connected in parallel with the series structure formed by the GDTs. The capacitors are configured to reduce the first breakdown voltage of the series structure formed by the GDTs in response to surge current. This allows the protection subcircuit to provide higher withstand voltage by connecting multiple GDTs in series, meeting the high-voltage protection requirements of medium-voltage power systems. Simultaneously, the voltage division effect of the parallel capacitors under transient high voltage prevents the protection subcircuit from failing to conduct when a low-voltage surge current occurs.

[0012] In one feasible implementation, the two capacitors have equal capacitance values. One end of one capacitor is connected to the first node, and one end of the other capacitor is connected to the second node. The other ends of both capacitors are connected to the power supply. The first and second nodes are connection nodes between two adjacent GDTs. The number of GDTs between the first and second nodes is the same as the number of GDTs between the first node and the power supply, and the number of GDTs between the second node and the power supply. In this way, by introducing capacitors of equal capacitance values ​​into the series GDT structure, when the surge current voltage does not exceed the breakdown threshold of the series GDT structure, a low-impedance path can still be formed through the capacitors, sequentially conducting the GDTs between each node and the power supply. This improves the consistency and response speed of the entire protection sub-circuit, ensuring that the multi-stage GDTs can still work reliably and collaboratively in complex electromagnetic environments.

[0013] In one feasible implementation, the reset sub-circuit includes a relay and a relay control module. The relay is connected in parallel with the protection sub-circuit, and the relay control module is disposed between the protection sub-circuit and the relay. The relay is configured to remain open when energized and closed when de-energized. The relay control module is configured to remain on when receiving current from a downstream circuit to supply power to the relay. This allows the protection sub-circuit to be reset after the surge current has dissipated, avoiding the risk of a short circuit due to continuous conduction.

[0014] In one feasible implementation, the relay control module includes a Zener diode with a cathode and an anode. The cathode is connected to the relay and subsequent circuitry, while the anode is connected to the protection sub-circuit and the power supply. The Zener diode is configured to remain on when it receives current from the subsequent circuitry or the relay at its cathode, thus supplying power to the relay. In this way, after the surge current has dissipated, the surge protection circuit can maintain power to the relay through the on-state of the Zener diode, ensuring the continuous operation of the relay control module and resetting the state of the protection sub-circuit.

[0015] In one feasible implementation, the relay includes a control coil and a switching structure. The two ends of the control coil are connected to the two ends of the relay control module. The control coil is configured to control the switching structure to disconnect the reset sub-circuit in response to power supply to the relay control module. Thus, the switching structure is open when energized and closed when de-energized, thereby achieving on / off control of the protection sub-circuit. When a surge current occurs, the protection sub-circuit conducts, and the relay control module closes the relay due to power loss, providing a path for subsequent reset. After the surge ends, the subsequent circuit is powered on, the Zener diode conducts, the relay control module is re-energized and maintains the relay in the open state, completing the automatic reset of the protection sub-circuit.

[0016] Secondly, embodiments of this application also provide an underwater medium-voltage conversion power supply, including: a power supply terminal; a subsequent circuit; and a surge protection circuit as provided in any of the foregoing embodiments, wherein the surge protection circuit is disposed between the power supply terminal and the subsequent circuit. In this way, the surge protection circuit can effectively suppress surges generated between the underwater medium-voltage conversion power supplies, ensuring stable operation of the power supply under complex operating conditions; through the coordinated design of the protection sub-circuit and the reset sub-circuit, rapid response and automatic recovery to surge events are achieved, effectively avoiding the risk of power outages or equipment damage caused by the inability of traditional protection circuits to reset in a timely manner. Attached Figure Description

[0017] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the power supply system for a submarine observation network.

[0019] Figure 2 This is a schematic diagram of an underwater power supply device.

[0020] Figure 3 The current-voltage characteristic curve of a TVS;

[0021] Figure 4 This is a schematic diagram of a surge protection circuit provided in an embodiment of this application;

[0022] Figure 5 A schematic diagram of a protection sub-circuit provided in an embodiment of this application;

[0023] Figure 6 A schematic diagram of a gas discharge tube provided in an embodiment of this application;

[0024] Figure 7This is a schematic diagram of another protective sub-circuit provided in an embodiment of this application;

[0025] Figure 8 This is a schematic diagram of another protective sub-circuit provided in an embodiment of this application;

[0026] Figure 9 This is a schematic diagram of a reset sub-circuit provided in an embodiment of this application;

[0027] Figure 10 This is a schematic diagram of the current flow direction of an underwater medium-voltage conversion power supply provided in an embodiment of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings.

[0029] In the description of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, "at least one" means one or more, and "multiple" means two or more. The terms "first," "second," etc., do not limit the quantity or order of execution, and "first," "second," etc., do not necessarily imply differences.

[0030] It should be noted that, in this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0031] The application scenarios of the embodiments of this application will be described below with reference to the accompanying drawings.

[0032] Figure 1 This is a schematic diagram of the power supply system for a submarine observation network.

[0033] A seabed observation network refers to a platform that installs various scientific instruments on the seabed to conduct long-term, dynamic, and real-time observations of the seawater layer and ocean floor, such as... Figure 1As shown, the power supply system of the seabed observation network includes a shore-based power supply equipment (PFE) 110 and an underwater observation medium voltage converter (OMVC) 120. The PFE 110 is typically located on the coast and obtains power through connection to the power grid to provide power to the entire seabed observation network. Multiple PFEs 110 are configured to form a loop, improving power supply reliability and preventing system-wide power outages due to single-point failures. For example, the PFE 110 can be connected to a 380V three-phase AC power grid on land, converting it to corresponding high-voltage DC power, which is then transmitted to the OMVC 120 via cables.

[0034] Furthermore, the OMVC 120 is typically deployed on the seabed, possessing high reliability and remote controllability, and can operate stably in complex marine environments. The OMVC 120 can receive high-voltage DC power transmitted via cable from the PFE 110, and utilize the power conversion module installed in the OMVC 120 to convert the received high-voltage DC power into medium- or low-voltage DC power that can be used by underwater load equipment in the seabed observation network.

[0035] However, due to the complex underwater environment and the transmission distance between PFE 110 and OMVC 120, the submarine cable used to transmit power may experience surge currents that impact the power supply system due to factors such as fishing operations, earthquakes, lightning, power grid switching, equipment start-up and shutdown, reef abrasion, and fish bites.

[0036] To prevent damage to the OMVC 120 due to high inrush current, surge protection circuitry needs to be designed inside the OMVC 120. This ensures that the inrush current generated by the power supply system will not affect the subsequent circuitry within the OMVC 120, minimizing the impact of inrush current on communication and the maintenance costs of the power supply system. It also prevents damage to normally operating equipment caused by inrush current generated after damage to submarine cables or other equipment.

[0037] Figure 2 This is a schematic diagram of an underwater power supply device.

[0038] like Figure 2 As shown, the OMVC 120 may include a power supply terminal 121, a protection unit 122, and a downstream circuit 123. The power supply terminal 121 receives the operating voltage to power the underwater load equipment in the submarine cable system. The operating voltage may be the high-voltage DC output from the PFE 110. After receiving the operating voltage from the power supply terminal 121, the downstream circuit 123 converts the high-voltage DC into medium- or low-voltage DC for use by the underwater load equipment in the submarine cable system, providing DC power adapted to the operating specifications of different underwater load equipment.

[0039] The protection unit 122 can be set between the power supply terminal 121 and the subsequent circuit 123 to provide surge current protection for the OMVC 120, prevent surge current from impacting the subsequent circuit 123 or even the underwater load equipment connected to the OMVC 120 and causing damage, and improve the operational stability of the OMVC 120.

[0040] For example, the electronic components constituting the protection unit 122 may be a transient voltage suppressor (TVS) and a metal oxide varistor (MOV), or a gas discharge tube (GDT). When subjected to a high-energy transient impact, the TVS can reduce its impedance and absorb a large current at an extremely high speed on the nanosecond scale, clamping the voltage between its terminals to a predetermined value, thereby ensuring that subsequent circuit components are protected from damage by the transient high-energy impact.

[0041] Figure 3 This is the current-voltage characteristic curve of a TVS.

[0042] like Figure 3 As shown, when the voltage received by the TVS is between 0 and the maximum reverse voltage V RWM Between these points, the leakage current I of the TVS is... R The voltage drop across the TVS is extremely small, and it can be considered an open circuit. The voltage received by the TVS is greater than or equal to the breakdown voltage V. BR When the impedance of the TVS decreases, the current in the branch with the TVS will change from I... T Rapidly rises to peak pulse current I PP And limit the voltage to the clamping voltage V. C Below, among which, V BR Greater than V RWM V C Greater than V BR And V RWM The voltage is greater than the normal operating voltage of the circuit protected by the TVS, V C It needs to be less than the maximum transient safe voltage that the circuit protected by the TVS can withstand.

[0043] However, based on the volt-ampere characteristic curve of a TVS, it can be seen that a TVS itself has a relatively fixed maximum reverse voltage, clamping voltage, and breakdown voltage, and these three are related as described above. Therefore, TVS is suitable for devices with low and constant operating voltages. However, for power supplies like OMVCs, where the operating voltage is not fixed and fluctuates within a large range with changes in output power, it is impossible to determine the maximum reverse voltage, clamping voltage, and breakdown voltage of the TVS used, thus failing to provide effective protection for the OMVC.

[0044] Specifically, if the selected TVS has a high breakdown voltage and maximum reverse voltage, then when the OMVC operates at low power and low voltage, or during the slow power-up process of the OMVC, a surge caused by an abnormal cable breakage or other event may occur. In this case, the surge current voltage drop may not reach the TVS breakdown voltage, and the TVS will not be able to provide effective protection for the downstream circuitry of the OMVC. Furthermore, due to the clamping characteristics of the TVS, the clamping voltage increases with increasing energy, and the large residual energy may affect the downstream power supply.

[0045] If the selected TVS breakdown voltage and maximum reverse voltage are too low, the TVS may be broken down by the operating current when the OMVC is operating at high power and high voltage, affecting the normal use of the OMVC.

[0046] To address the aforementioned issues, this application provides a surge protection circuit that can be installed in an underwater medium-voltage converter to provide surge protection for the underwater medium-voltage converter.

[0047] Figure 4 This is a schematic diagram of a surge protection circuit provided in an embodiment of this application.

[0048] In the embodiments of this application, such as Figure 4 As shown, the surge protection circuit 410 can be installed in the underwater medium-voltage conversion power supply, which can also include a power supply terminal 420 and a downstream circuit 430. The power supply terminal 420 can receive electrical energy from the shore-based power supply to provide power to the downstream circuit 430 and the underwater load equipment connected to it. The downstream circuit 430 can then convert the high-voltage DC power received by the power supply terminal 420 into medium-voltage or low-voltage DC power that the underwater load equipment can utilize.

[0049] The surge protection circuit 410 is located between the power supply terminal 420 and the subsequent circuit 430. It is used to discharge the surge current when the power supply terminal 420 receives a surge current, so as to avoid affecting the subsequent circuit 430.

[0050] For example, the surge protection circuit 410 may include a protection sub-circuit 411 and a reset sub-circuit 412. The protection sub-circuit 411 can be turned on when a surge current is received at the power supply terminal 420 to discharge the surge current and prevent it from damaging the electronic components in the subsequent circuit 430. The reset sub-circuit 412 can be used to reset the protection sub-circuit 411 after it has discharged the surge current, so as to prevent the electrical energy input at the power supply terminal 420 from being unable to be transmitted to the subsequent circuit 430 and the underwater load equipment after the surge current has been discharged.

[0051] In this embodiment of the application, the protection sub-circuit 411 is disposed between the power supply terminal 420 and the subsequent circuit 430, and the protection sub-circuit 411 can be connected in parallel with the subsequent circuit 430. In this way, the protection sub-circuit 411 can short-circuit the entire subsequent circuit 430 in the event of a surge current in the line, so as to avoid the surge current impacting the subsequent circuit 430.

[0052] Specifically, the protection sub-circuit 411 may include at least one protection device. The protection device can respond to changes in the input voltage at the power supply terminal 420. When the rate of change of the input voltage is greater than a preset threshold and the value of the input voltage is greater than the breakdown voltage of the protection device, the protection sub-circuit 411 is turned on and the downstream circuit 430 of the underwater medium-voltage conversion power supply is short-circuited accordingly, so as to prevent the current with large voltage changes from affecting the operation of the downstream circuit 430.

[0053] It should be understood that the protective device has a high impedance when the voltage across its terminals is below the breakdown voltage, allowing the circuit in the protective sub-circuit 411 to remain in an approximately open-circuit state. The input voltage received by the power supply terminal 420 is shunted to the protective sub-circuit 411, reducing the power loss of the underwater medium-voltage conversion power supply. When the voltage across the protective device is above the breakdown voltage, the impedance of the protective device drops sharply to discharge the current. In this way, multiple protective devices connected in series can power down the subsequent circuit 430 connected in parallel with the protective devices, preventing the subsequent circuit 430 from being subjected to high-voltage current surges.

[0054] After at least one protective device is installed, the protective sub-circuit 411 can be turned on when the rate of change of the input voltage at the power supply terminal 420 is greater than a preset threshold and the input voltage is greater than the first breakdown voltage of the protective sub-circuit 411, so as to power down the subsequent circuit 430. For example, when there are two or more protective devices in the protective sub-circuit 411, the multiple protective devices can be connected in series in sequence. In this case, the first breakdown voltage of the protective sub-circuit 411 can be the sum of the breakdown voltages of the multiple protective devices. When there is only one protective device in the protective sub-circuit 411, the first breakdown voltage of the protective sub-circuit 411 can be the same as the breakdown voltage of the protective device.

[0055] It should be noted that when there are two or more protective devices in the protective sub-circuit 411, each protective device in the protective sub-circuit 411 has the same type and specifications. If the protective device is a gas discharge tube, the breakdown voltage and other specifications of each protective device are the same, so as to avoid the gas discharge tubes of different specifications from affecting the operational stability of the protective sub-circuit 411.

[0056] Figure 5 This is a schematic diagram of a protection sub-circuit provided in an embodiment of this application.

[0057] like Figure 5 As shown, the protective device in the protective sub-circuit 411 can be a gas discharge tube (GDT). Each GDT has the same breakdown voltage, which is the second breakdown voltage. The GDT can be turned on when the rate of change of the voltage across its terminals is greater than a preset threshold and the voltage value is greater than the second breakdown voltage.

[0058] In some embodiments of this application, the preset threshold for the voltage change rate corresponding to the GDT can be 100V / s, and the second breakdown voltage of the GDT can be 500V. Taking a GDT in the protection sub-circuit 411 as an example, the GDT will only be turned on when the voltage change rate is higher than 100V per second and the voltage value at both ends is greater than 500V.

[0059] It should be understood that after the GDT is turned on, it will discharge overvoltage energy to the low-voltage side, thereby effectively suppressing the impact of transient high voltage on the subsequent circuit. At this time, the input current i0 is greater than the current i1 discharged by the GDT, and the remaining current i2 will flow to the subsequent circuit 430. Since most of the energy has been discharged, the remaining current i2 is insufficient to damage the subsequent circuit 430, thus achieving effective protection.

[0060] Figure 6 This is a schematic diagram of a gas discharge tube provided in an embodiment of this application.

[0061] In some embodiments of this application, the GDT may include two pins 61 and two electrodes 62, wherein one end of each pin 61 may be electrically connected to the electrode 62, and the other end of the two pins 61 may be connected to the corresponding line of the protection sub-circuit 411. For example, in a scenario where the protection sub-circuit 41 is provided with multiple GDTs, the other end of each GDT's pin 61 may be electrically connected to achieve sequential series connection of multiple GDTs.

[0062] The two electrodes 62 in the GDT can be arranged in parallel, and there is a preset distance between the two electrodes 62. The second breakdown voltage of the GDT is related to the preset distance between the two electrodes 62. Specifically, under the condition that other factors remain unchanged, the larger the preset distance, the higher the second breakdown voltage of the GDT.

[0063] In this embodiment, the protective device in the protective sub-circuit 411 can be a single GDT with a large electrode spacing, or it can be multiple GDTs with small electrode spacing arranged in series. For example, when there is only one GDT in the protective sub-circuit 411, the preset spacing between the GDTs can be 2mm to 3mm; when there are multiple GDTs in the protective sub-circuit 411, the preset spacing between the GDTs can be 0.5mm to 1mm.

[0064] It should be noted that because the manufacturing tolerance of components will increase the breakdown voltage dispersion of GDTs with small electrode spacing, and the breakdown voltage of a single GDT is too low, affecting the response speed of the protection sub-circuit 411, the preset spacing of the GDTs used in this embodiment can be greater than or equal to 0.5mm.

[0065] In some embodiments of this application, the breakdown voltage of the protection sub-circuit 411 formed by connecting multiple GDTs in series is the sum of the values ​​of the multiple GDTs, that is, the sum of the first breakdown voltage and the second breakdown voltage corresponding to each GDT. Furthermore, because the operating voltage of the underwater medium-voltage converter power supply fluctuates within a certain range, the value of the first breakdown voltage needs to be higher than the maximum operating voltage of the underwater medium-voltage converter power supply. This is to prevent voltage fluctuations during normal operation of the underwater medium-voltage converter power supply from falsely triggering the GDTs and causing the protection sub-circuit 411 to conduct, thereby reducing the number of false triggers of the GDTs and slowing down the aging rate of the GDTs.

[0066] Taking a maximum operating voltage of 2500V for the underwater medium-voltage converter as an example, the first breakdown voltage of multiple GDTs connected in series needs to be higher than 2500V to prevent the input voltage received by the power supply terminal 420 from triggering the protection sub-circuit 411 to conduct, causing the subsequent circuit 430 to lose power. For example, when the maximum operating voltage of the underwater medium-voltage converter is 2500V, the first breakdown voltage corresponding to the protection sub-circuit 411 can be 3000V to reduce the possibility of the operating voltage received by the power supply triggering the GDT in the protection sub-circuit 411 to conduct.

[0067] Figure 7 This is a schematic diagram of another protective sub-circuit provided in an embodiment of this application.

[0068] Because the operating voltage of the underwater medium-voltage converter can fluctuate within a certain range, when the operating voltage of the power supply is maintained at a low level, the protection sub-circuit 411, which uses a single high-breakdown-voltage GDT as a protection device, has a problem of untimely response and cannot protect against surge current when the operating voltage received by the underwater medium-voltage converter is low. Therefore, in this embodiment, multiple GDTs with lower breakdown voltages can be set in the protection sub-circuit 411, and a surge current discharge line with lower impedance can be set to avoid the problem of untimely surge current protection response when the operating voltage of the underwater medium-voltage converter is low.

[0069] like Figure 7 As shown in (a), when multiple GDTs are provided in the protection sub-circuit 411, such as when two GDTs are provided in the protection sub-circuit 411, the breakdown voltage of the protection sub-circuit 411 is the sum of the breakdown voltages of the two GDTs, that is, the first breakdown voltage is equal to the superposition of the second breakdown voltages of the two GDTs. This reduces the breakdown voltage of a single GDT, thereby improving the response speed of the protection sub-circuit to surge signals under low operating voltage. At the same time, the series connection structure of multiple GDTs ensures that the overall breakdown voltage is still higher than the maximum operating voltage of the underwater medium-voltage converter, ensuring that it is not falsely triggered during normal operation, thus balancing response speed and operational stability.

[0070] Furthermore, the protection sub-circuit 411 may also include a capacitor to provide a lower impedance line for the underwater medium-voltage conversion power supply. When the protection sub-circuit 411 receives a low-voltage surge current, because the surge current is a high-frequency transient signal, the capacitor can respond to the surge current to form a low-impedance path, thereby reducing the first breakdown voltage of the GDT series structure.

[0071] When a surge current occurs, it flows through the branch containing the capacitor, activating at least one gate current transformer (GDT) and sequentially activating GDTs connected in series with the activated GDT. This puts the protection sub-circuit 411 in a low-impedance state, dissipating the surge current. For example, a surge current with a voltage lower than the first breakdown voltage can be activated by sequentially activating the GDTs in the protection sub-circuit 411 through the line containing the capacitor when the surge current voltage is higher than the second breakdown voltage of at least one GDT, thereby achieving surge current protection for the subsequent circuit 430.

[0072] For example, such as Figure 7 As shown in (b), the protection sub-circuit 411 may have three GDTs and two capacitors. One end of the two capacitors is connected to the connection point of the two GDTs, and the other end is connected to the power supply terminal 420. The three GDTs in the protection sub-circuit 411 may be G1, G2, and G3, and the two capacitors may be C1 and C2 as shown in the figure. One end of capacitor C1 is set on the line between G1 and G2, and the other end of capacitor C1 is set on the line between the protection sub-circuit 411 and the power supply terminal 420. One end of capacitor C2 is set on the line between G2 and G3, and the other end of capacitor C2 is set on the line between the protection sub-circuit 411 and the reset sub-circuit 412.

[0073] like Figure 7As shown in (b), when the underwater medium-voltage converter receives a surge current, if the voltage of the surge current is lower than the first breakdown voltage of the protection sub-circuit 411 but higher than the second breakdown voltage of a single GDT, capacitors C1 and C2 will charge rapidly and form a low-impedance path, causing G1 to conduct preferentially. After G1 conducts, the line voltage rises further, triggering the breakdown conduction of G2 and G3 in sequence, achieving a cascaded response. This process shortens the overall response time of the multi-stage GDT and improves the sensitivity to low-voltage surges. At the same time, since the capacitor can be regarded as an open circuit in the DC steady-state state of the underwater medium-voltage converter, the introduction of the parallel capacitor structure does not change the withstand voltage characteristics of the protection sub-circuit 411 in steady-state operation, ensuring that the protection sub-circuit maintains a high-impedance state when the power supply is operating normally, while avoiding surge currents with voltages not exceeding the operating voltage of the underwater medium-voltage converter from affecting the normal operation of the subsequent circuit 430.

[0074] Figure 8 This is a schematic diagram of another protective sub-circuit provided in an embodiment of this application.

[0075] In some embodiments of this application, the number of GDTs in the protection sub-circuit 411 can also be six. The protection structure formed by the six GDTs connected in series can be connected in parallel with the reset sub-circuit 412 and the subsequent circuit 430 to protect the subsequent circuit 430. Figure 8 As shown, the protection sub-circuit 411 can be equipped with six GDTs: G1, G2, G3, G4, G5, and G6. Since the underwater medium-voltage conversion power supply can be used to convert high-voltage DC to low-voltage DC, the input voltage received by the power supply terminal 420 can be a DC current. The power supply terminal 420 has a high-voltage terminal and a low-voltage terminal. The underwater medium-voltage conversion power supply can utilize the high-voltage terminal and the low-voltage terminal of the power supply terminal 420 to form a power supply circuit for the underwater load equipment.

[0076] Meanwhile, the capacitor in the protection sub-circuit 411 can be placed between the node formed by the GDTs connected in series and the power supply terminal 420. For example, the GDTs connected in series can form a first node and a second node, which are connection nodes between two adjacent GDTs, and the number of GDTs between the first node and the second node is the same as the number of GDTs between the first node and the power supply terminal, and the number of GDTs between the second node and the power supply terminal.

[0077] Specifically, the protection sub-circuit 411 can be set between the high-voltage end and the low-voltage end of the power supply terminal 420, so that after the protection sub-circuit 411 is turned on, it forms a loop with the high-voltage end and the low-voltage end of the power supply terminal 420, discharging the surge current from the high-voltage end to the low-voltage end. The GDTs in the protection sub-circuit 411 can be arranged in the direction from the high-voltage end to the low-voltage end of the power supply terminal 420, from G6 to G1.

[0078] Taking the protection sub-circuit 411, which includes two capacitors, as an example, the two capacitors have the same capacitance value. This ensures that the charging and conduction speeds of the branches corresponding to the two capacitors are similar when a surge current occurs, thus optimizing the response consistency of the protection sub-circuit 411. Furthermore, the two capacitors are connected in parallel, forming a parallel structure with the GDT (Gas Discharge Transistor). This allows energy to be preferentially discharged through the capacitor-gas discharge tube composite path when a surge current occurs, optimizing the response speed of the series structure formed under the GDT. Simultaneously, the equivalent impedance of the capacitor-GDT series branch is significantly reduced under high-frequency surges, further improving the response efficiency of the protection sub-circuit to transient overvoltages.

[0079] For example, one end of capacitor C1 is connected to the first node between G2 and G3, and the other end of capacitor C1 is set on the line between the protection sub-circuit 411 and the power supply terminal 420. One end of capacitor C2 is connected to the second node between G4 and G5, and the other end of capacitor C2 is set on the line between the protection sub-circuit 411 and the reset sub-circuit 412.

[0080] When the underwater medium-voltage converter receives a surge current, refer to Figure 8 In the circuit structure shown, capacitors C1 and C2 charge rapidly to form a low-impedance path. The surge current preferentially forms a momentary conduction loop along the path of capacitor C1, causing G1 and G2 to reach the breakdown threshold simultaneously. Subsequently, G3 and G4, and G5 and G6 are turned on sequentially. In this way, the protection sub-circuit 411 can respond to the received current and turn on when the rate of change of current and voltage received at the power supply terminal 420 is greater than a preset threshold. This avoids the situation where the surge voltage drop of the surge current generated when the operating voltage of the underwater medium-voltage conversion power supply is low cannot trigger the protective function of the protection sub-circuit 411.

[0081] It should be understood that, Figure 7 and Figure 8 The number of GDTs shown is only one of the feasible implementations in this application embodiment. In actual applications, the number of GDTs can be flexibly adjusted according to actual protection requirements and the specifications of the GDTs used. For example, when the working environment has higher requirements for surge suppression capability, the number of GDT stages can be increased to improve the withstand voltage level. At the same time, the layout of GDTs can also be optimized and adjusted according to the circuit topology, and this application embodiment does not impose any limitations.

[0082] Furthermore, the capacitor arrangement shown in this embodiment is merely an example; in practice, the number and connection positions of capacitors can be adjusted according to response speed and filtering requirements. For instance, in scenarios requiring faster response, a capacitor can be connected in parallel between every two adjacent GDTs to further improve the bypass efficiency of high-frequency surges. This embodiment does not limit the number of capacitors in the protection sub-circuit 411.

[0083] Furthermore, the surge current generated in the power supply system of the submarine observation network is usually affected by the environment or the start-up and shutdown of equipment. The duration of the generated current is usually in the microsecond or even millisecond range. Depending on the type of protective device used, the protection sub-circuit 411 may have a long conduction time or may not be able to reset automatically, affecting the operation of the underwater medium-voltage conversion power supply after the occurrence of surge current.

[0084] In the embodiments of this application, such as Figure 7 and Figure 8 As shown, by setting a reset sub-circuit 412 in the surge protection circuit 410, the protection sub-circuit 411 is reset after the surge current ends. In this embodiment, the reset sub-circuit 412 is located between the protection sub-circuit 411 and the subsequent circuit 430. The reset sub-circuit 412 can be used to turn itself on after the protection sub-circuit 411 is turned on, so as to restore the impedance of the protection device in the protection sub-circuit 411. In this way, after the surge current is discharged by the protection sub-circuit 411, the subsequent circuit 430 can recover from the power failure state, avoiding the impact of prolonged power failure of the subsequent circuit 430 on the normal operation of the underwater load equipment.

[0085] Specifically, the reset sub-circuit 412 can be a switch structure connected in parallel with the protection sub-circuit 411. The reset sub-circuit 412 can adjust its own state by monitoring the state of the protection sub-circuit 411, thereby turning the reset sub-circuit 412 on or off. For example, during the operation of the underwater medium-voltage conversion power supply, if the protection sub-circuit 411 is always in an open circuit state, the reset sub-circuit 412 will also be in an open circuit state, preventing the downstream circuit 430 from losing power without a surge current. If the protection sub-circuit 411 is in a conducting state, the reset sub-circuit 412 can be turned on based on the conducting state of the protection sub-circuit 411, thereby short-circuiting the protection sub-circuit 411, restoring the impedance of the protection device in the protection sub-circuit 411, and realizing the function of resetting the protection sub-circuit 411.

[0086] Figure 9 This is a schematic diagram of a reset circuit provided in an embodiment of this application.

[0087] It should be understood that when the reset sub-circuit 412 is turned on, it can provide a lower impedance loop to the input voltage of the power supply terminal 420 compared to the impedance of the protection sub-circuit 411 after it is turned on, thus short-circuiting the protection sub-circuit 411 after it is turned on, thereby preventing current from flowing through the protection sub-circuit 411 and restoring the protection device in the protection sub-circuit 411 to a high impedance state, thereby achieving the purpose of resetting the protection sub-circuit 411. Figure 9As shown, the reset sub-circuit 412 may include a relay 4121 and a relay control module 4122. The relay 4121 can control the switching of the on or off state of the reset sub-circuit 412 by opening or closing itself. The relay control module 4122 can control the on or off state of the reset sub-circuit 412 by controlling the opening or closing of the relay 4121.

[0088] For example, relay 4121 can be a normally closed relay. A normally closed relay may have a control terminal and a switching structure. The two ends of the switching structure are respectively connected to circuits and connected in parallel with the protection sub-circuit 411. The opening and closing of the switching structure can be controlled by the control terminal. A normally closed relay has the characteristic that the switching structure remains open when the control terminal is energized and remains closed when the power is off. Therefore, relay 4121 can connect or disconnect the reset sub-circuit 412 depending on whether the control terminal is energized.

[0089] Furthermore, the control terminal of relay 4121 can be a control coil, and the switching structure can include an armature, a contact, and a spring. The spring is disposed between the control coil and the armature. When the control coil is not energized, the armature is in contact with the contact. After energization, the control coil can generate a magnetic field that attracts the armature in the switching structure, breaking the contact between the armature and the contact. The armature is then compressed by the spring, disconnecting the reset circuit 412. After the control coil is de-energized, it no longer generates a magnetic field, and the armature can return to its original shape after the spring, making contact with the contact to conduct the reset circuit 412.

[0090] In this embodiment, the relay control module 4122 can be connected to the control terminal of the relay 4121. The relay control module 4122 can maintain the conducting state when receiving the return current from the downstream circuit 430 and supply power to the control terminal of the relay 4121 so that when the downstream circuit 430 is in the running state, it controls the reset sub-circuit 412 to be in the open state, so as to avoid the downstream circuit 430 from losing power due to the closure of the reset sub-circuit 412.

[0091] For example, the relay control module 4122 may include a Zener diode, which may be disposed between the reset sub-circuit 412 and the protection sub-circuit 411. The two ends of the control terminal of the relay 4121 are electrically connected to the two ends of the Zener diode in the relay control module 4122. In this way, the Zener diode can be used to receive the current from the subsequent circuit 430 to control the energization of the control terminal of the relay 4121, thereby controlling the conduction and disconnection of the reset sub-circuit 412.

[0092] In this embodiment, the Zener diode has a cathode and an anode. The cathode is connected to the relay 4121 and the subsequent circuit 430, while the anode is connected to the protection sub-circuit 411 and the power supply terminal 420. When the Zener diode receives a current with a voltage value exceeding its breakdown voltage, it provides an operating voltage to the control terminal of the relay 4121, causing the control terminal to keep the relay 4121 in the open state. This ensures that the operating voltage input to the power supply terminal 420 flows through the subsequent circuit 430, thereby maintaining the normal operation of the subsequent circuit 430 and the underwater load equipment connected to the underwater medium-voltage conversion power supply.

[0093] It should be understood that when the protection sub-circuit 411 is conducting, the Zener diode receives no current and does not supply power to the control terminal of the relay 4121, keeping the relay 4121 in a closed state. At this time, the impedance of the reset sub-circuit 412 is lower than that of the conducting protection sub-circuit 411. After the relay 4121 is closed, the current can be transmitted through the loop formed by the reset sub-circuit 412 and the power supply terminal 420 to short-circuit the protection sub-circuit 411, restoring the impedance of the GDT to its state before conduction. The current transmitted through the reset sub-circuit 412 can also trigger the Zener diode, thereby supplying power to the control terminal of the relay 4121 and disconnecting the conduction state of the reset sub-circuit 412. This allows the operating voltage input from the power supply terminal 420 to be transmitted to the subsequent circuit 430 after the surge current ends, maintaining the normal operation of the underwater medium-voltage conversion power supply.

[0094] Figure 10 This is a schematic diagram of the current flow direction of an underwater medium-voltage conversion power supply provided in an embodiment of this application.

[0095] Taking the protection sub-circuit 411 as an example, which includes six GDTs and two capacitors, the reset sub-circuit 4122 with a normally closed relay 4121 and a relay control module 4122 including a Zener diode, as an example, Figure 10 As shown in (a), in some embodiments of this application, when no surge current is generated in the power supply system and it is in operation, the electrical energy input to the power supply terminal 420 is relatively stable and will not trigger the conduction of the protection sub-circuit 411. At this time, the current can be transmitted through the line to the subsequent circuit 430 to supply power to the subsequent circuit 430. After the power supply current flows through the subsequent circuit 430, it will continue to be transmitted to the Zener diode corresponding to the relay control module 4122, and supply power to the control terminal of the relay 4121 by reverse breakdown of the Zener diode, so as to keep the relay 4121 always in the open state and prevent the reset sub-circuit 412 from remaining in the conducting state after being broken down.

[0096] If a surge current is generated in the power supply system and transmitted to the underwater medium-voltage conversion power supply... Figure 10As shown in (b), when the rate of change of the voltage of the surge current exceeds the preset threshold range of the protection sub-circuit 411, the protection sub-circuit 411 can respond to the surge current and conduct under the influence of the voltage difference, or form a low impedance path by charging capacitors C1 and C2, so that the six GDTs conduct in sequence, quickly dissipating the surge current and preventing it from entering the subsequent circuit 430.

[0097] At this time, the protection sub-circuit 411 is in a low impedance state. Most of the current input from the power supply terminal 420 will be discharged through the corresponding conduction path of the protection sub-circuit 411. Only a small part of the current flows through the subsequent circuit 430, and the voltage of this part of the current will not affect the safety of the subsequent circuit 430, nor is it enough to break down the Zener diode. The relay control module 4122 cannot maintain the power supply state, and the relay 4121 returns to the normally closed state due to power loss, so that the reset sub-circuit 412 is turned on.

[0098] When the surge current subsides and the voltage at the power supply terminal returns to normal, such as Figure 10 As shown in (c), the Zener diode will be reverse-biased again, the output voltage will drive relay 4121 to disconnect, completing the reset action, the system will return to normal operation, and the current flow will return to normal. Figure 10 The direction of flow is shown in (a).

[0099] Based on the surge protection circuit structure provided in the above embodiments, the underwater medium-voltage conversion power supply can respond quickly and complete self-protection when a surge current occurs, and automatically restore power supply after the surge ends without manual intervention. This design, through the synergistic effect of the protection sub-circuit and the reset sub-circuit, achieves efficient protection and continuous operation assurance for downstream circuits, improving the reliability and stability of the system in complex underwater environments, and is suitable for long-term high-voltage power transmission scenarios. Especially in deep-sea high-pressure and highly corrosive environments, this circuit structure effectively avoids equipment downtime or component aging caused by transient voltage surges. Through the precise coordination of the Zener diode and the relay, the system can automatically reset within hundreds of milliseconds after the surge ends, ensuring power supply continuity.

[0100] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0101] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0102] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0103] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0104] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, essentially or in other words, the parts that contribute to the prior art, or all or part of the technical solutions, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0105] The above content is only a specific implementation of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the protection scope of this application.

Claims

1. A surge protection circuit, characterized in that, This is applied to an underwater medium-voltage conversion power supply, which includes a power supply terminal and a subsequent circuit. The surge protection circuit includes a protection sub-circuit and a reset sub-circuit, wherein: The protection sub-circuit is disposed between the power supply terminal and the subsequent circuit, and the protection sub-circuit is connected in parallel with the subsequent circuit; the protection sub-circuit includes at least one protection device, and the protection sub-circuit is configured to conduct when the rate of change of the input voltage at the power supply terminal is greater than a preset threshold and the input voltage is greater than the first breakdown voltage of the protection sub-circuit, so as to short-circuit the subsequent circuit. The reset sub-circuit is disposed between the protection sub-circuit and the subsequent circuit. The reset sub-circuit is connected in parallel with the protection sub-circuit. The reset sub-circuit is configured to close the circuit to reset the protection sub-circuit after the protection sub-circuit is turned on. The reset sub-circuit includes a relay and a relay control module. The relay is connected in parallel with the protection sub-circuit, and the relay control module is disposed between the protection sub-circuit and the relay. The relay is configured to remain in an open state when energized and remain in a closed state when de-energized. The relay control module includes a Zener diode with a cathode and an anode. The cathode is connected to the relay and the subsequent circuit, and the anode is connected to the protection sub-circuit and the power supply terminal. The Zener diode is configured to remain in a conducting state when the cathode receives current from the subsequent circuit or the relay, so as to supply power to the relay.

2. The surge protection circuit according to claim 1, characterized in that, The protective device is a gas discharge tube (GDT), which has a second breakdown voltage. The GDT is configured to conduct when the rate of change of the voltage across the GDT is greater than a preset threshold and the voltage value across the GDT is greater than the second breakdown voltage. The value of the first breakdown voltage is the same as the sum of the second breakdown voltages of the GDT in the protection sub-circuit.

3. The surge protection circuit according to claim 2, characterized in that, The GDT includes two pins and two electrodes, with a preset spacing between the two electrodes. One end of each pin is electrically connected to one of the electrodes, and the other end of the pin is electrically connected to the line corresponding to the protection sub-circuit.

4. The surge protection circuit according to claim 2, characterized in that, The protection subcircuit also includes at least one capacitor. When the protection subcircuit includes at least two GDTs, one end of the capacitor is disposed between two adjacent GDTs, and the other end of the capacitor is electrically connected to the power supply terminal to reduce the breakdown voltage of the protection subcircuit after the at least two GDTs are connected in series when a surge current is generated.

5. The surge protection circuit according to claim 2, characterized in that, The protection sub-circuit includes six GDTs connected in series, and each GDT is connected in parallel with the reset sub-circuit and the subsequent circuit. The protection sub-circuit also includes two capacitors connected in parallel. The two capacitors are respectively connected in parallel with the series structure formed by the GDT. The capacitors are configured to reduce the first breakdown voltage of the series structure formed by the GDT in response to surge current.

6. The surge protection circuit according to claim 5, characterized in that, The two capacitors have equal capacitance values. One end of one capacitor is connected to the first node, and one end of the other capacitor is connected to the second node. The other ends of the two capacitors are respectively connected to the power supply terminal. The first node and the second node are the connection nodes between two adjacent GDTs. The number of GDTs between the first node and the second node is the same as the number of GDTs between the first node and the power supply terminal, and the number of GDTs between the second node and the power supply terminal.

7. The surge protection circuit according to claim 1, characterized in that, The relay includes a control coil and a switching structure. The two ends of the control coil are respectively connected to the two ends of the relay control module. The control coil is configured to control the switching structure to disconnect the reset sub-circuit in response to the power supply of the relay control module.

8. An underwater medium-voltage conversion power supply, characterized in that, include: Power supply end; Post-stage circuit; The surge protection circuit as described in any one of claims 1-7, wherein the surge protection circuit is disposed between the power supply terminal and the subsequent circuit.

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