High voltage bypass device, voltage source converter, and method of operation

Abstract

The present disclosure relates to a high voltage bypass device (10) comprising a cavity (13), a trigger element arranged in the cavity (13), a reservoir (17) filled with an electrically conductive flowable material (18), and a shutter (19) separating the cavity (13) and the reservoir (17). The trigger element is connected to a first terminal (11) and a second terminal (12) of the high voltage bypass device (10). The shutter (19) is configured to open a passage between the cavity (13) and the reservoir (17) in case the trigger element is triggered by an overvoltage condition, such that the electrically conductive flowable material (18) at least partially fills the cavity (13) forming an electrically conductive path from the first terminal (11) to the second terminal (12). The present disclosure further relates to a voltage source converter (VSC), in particular a modular multilevel converter (40), and a method for operating a high voltage bypass device (10).

Description

Technical Field

[0001] This disclosure relates to high-voltage bypass devices, their application in voltage source converters, and methods of operating high-voltage bypass devices. Background Technology

[0002] High-voltage (HV) devices, such as voltage converters operating at voltages exceeding 1 kV or higher, typically include multiple switching devices, such as power semiconductor switching devices, that selectively connect or disconnect two different voltage potentials. For example, so-called Modular Multi-cell Converters (MMCs) include multiple switching units to generate the desired output voltage from a given input voltage. Such converters are useful, for example, in high-voltage direct current (HVDC) transmission systems. Because such devices are part of critical infrastructure, they must operate reliably, even in the event of a failure in a single component of the converter.

[0003] It is well known that mechanical bypass switches (BPS) or circuit breakers are used to bypass faulty switching components. However, providing additional electromechanical components increases the overall complexity and cost of the device significantly. Alternatively, specific semiconductor protection devices can be used. However, because high-voltage devices involve large voltages and currents, semiconductor-based protection devices typically require active cooling, which also increases the complexity and cost of high-voltage devices. If these components are redundantly provided, for example to meet reliability requirements, the added complexity and cost can double. Summary of the Invention

[0004] This disclosure provides alternative devices, systems, and methods for ensuring the reliable operation of high-voltage installations.

[0005] According to a first aspect, a high-voltage bypass device is disclosed. The device includes a cavity, a trigger element disposed within the cavity, a reservoir filled with a conductive, flowable material, and a shutter separating the cavity and the reservoir. The trigger element is connected to a first terminal and a second terminal of the high-voltage bypass device. The shutter is configured to open a channel between the cavity and the reservoir when the trigger element is triggered by an overvoltage condition, such that the conductive material at least partially fills the cavity, thereby forming a conductive path from the first terminal to the second terminal.

[0006] The device according to the first aspect can bypass another device or part of a high-voltage device. Unlike known bypass devices, the disclosed bypass device does not require any form of active control or forced cooling. Therefore, such a device is relatively easy to construct and integrate even in existing devices.

[0007] In at least one embodiment, the triggering element includes a first electrode connected to a first terminal and a second electrode connected to a second terminal, the first and second electrodes extending into a cavity and forming a spark gap therein. The spark gap is relatively easy to form and generates a spark under overvoltage conditions, which can be used to release the gate almost immediately. Furthermore, after the bypass device is triggered, the electrode forming the spark gap can form a portion of a conductive path.

[0008] In at least one embodiment, the triggering element includes a varistor connected between a first terminal and a second terminal. Varistors have well-known electrical characteristics. Specifically, they can enter a conductive state above a defined threshold voltage (called a clamping voltage). Due to ohmic losses in the conductive state, the varistor generates heat, which can be used to release the gate.

[0009] In at least one embodiment, the conductive flowable material includes at least one of liquid, powder, and / or granular materials. For example, these materials can flow freely from the reservoir into the cavity under the influence of gravity or other external forces.

[0010] In at least one embodiment, the conductive, flowable material includes at least one of a metal or metal alloy, particularly gallium (Ga), gallium indium tin (Galinstan), mercury (Hg), aluminum (Al), or copper (Cu). Metallic materials have very high conductivity and are therefore suitable for carrying the high currents typically found in high-voltage devices.

[0011] In at least one embodiment, the triggering element is configured to generate heat under overvoltage conditions, and the gate comprises a thermosensitive material, particularly a polymeric material, which is at least partially destroyed by one of melting, evaporation, or combustion. This material can be designed to reliably activate the gate mechanism in the event of a spark or other predefined thermal event within the cavity.

[0012] According to different embodiments, the gate includes a thermal membrane that separates the cavity from the reservoir or a spring-loaded thermal trigger coupled to separate the cavity from the reservoir. Either solution provides a simple mechanical gate mechanism that can be activated by heat generated under overvoltage conditions.

[0013] In at least one embodiment, the reservoir is positioned above the cavity at the device's mounting location, such that when the trigger element is activated, the conductive, flowable material is released under gravity, thereby opening the gate. This gravity-driven mechanism is particularly reliable and does not rely on any external energy source or control.

[0014] According to at least one embodiment, the triggering element includes a first electrode connected to a first terminal and a second electrode connected to a second terminal, the first and second electrodes forming a spark gap. The first electrode is disposed at the bottom of the cavity and protrudes upward, while the second electrode is disposed at the top of the cavity near the gate and protrudes downward. Alternatively or additionally, the first electrode is disposed on the first wall of the cavity and protrudes toward the opposite second wall of the cavity, and the second electrode is disposed on the second wall of the cavity and protrudes toward the first wall of the cavity, wherein a direct path between the first and second electrodes is close to the gate. These arrangements ensure that the energy of the spark will reliably trigger the gate mechanism.

[0015] According to at least one embodiment, the triggering element includes a varistor connected between a first terminal and a second terminal. The varistor is disposed in the central portion of a cavity below the gate. Alternatively or additionally, the varistor is arranged in direct thermal contact with the gate. These arrangements ensure that the heat generated by the varistor will reliably trigger the gate mechanism.

[0016] According to at least one embodiment, the cavity is filled with a vacuum or a protective gas before the triggering element is activated. This may be advantageous in certain operating environments where accidental discharge or chemical corrosion of the electrodes should be avoided.

[0017] In at least one embodiment, a conductive, flowable material is configured to form a permanent electrical path between the first and second terminals after the triggering element is actuated. This can be achieved in various ways, such as by flooding the cavity with a conductive liquid, or by contacting the first and second electrodes extending into or defining the cavity with a particulate conductive medium. The formation of the permanent electrical path enables the high-voltage device to remain operational for a relatively long period, for example, until a fault in another component is identified and resolved.

[0018] According to a second aspect, a voltage source converter (VSC), particularly a modular multi-cell converter (MMC), is provided. The converter includes at least one switching unit configured to switch a high voltage and at least one high-voltage bypass device according to a first aspect, the high-voltage bypass device being configured to bypass at least one switching unit in the event of a fault.

[0019] In the event of a fault in the switching unit, the converter maintains partial or full operation according to the second aspect. In this case, the switching unit can be bypassed via a high-voltage bypass device, thereby providing a path for current bypass of the unit.

[0020] In at least one embodiment, the switching unit includes at least one power semiconductor switching device, particularly an IGBT, and a high-voltage bypass device is connected in parallel with the at least one power semiconductor switching device. In this way, the core switching components of the switching unit can be bypassed.

[0021] According to at least one embodiment, the switching unit further includes at least one mechanical bypass switch connected in parallel with at least one power semiconductor switching device and a high-voltage bypass device. This converter combines the advantages of the mechanical bypass switch with the additional safety of the high-voltage bypass device according to the first aspect. For example, the mechanical bypass switch can be activated or deactivated multiple times by an external control signal, or may have other advantages. In the event that the mechanical bypass switch fails to close, the high-voltage bypass device can be activated without external control. Furthermore, it fulfills the requirement of providing redundant bypass components, thereby avoiding the risks associated with the failure of a single safety component.

[0022] In at least one embodiment, at least one switching unit has a rated voltage exceeding 1 kV, preferably exceeding 3 kV, and / or a rated current exceeding 100 A, preferably exceeding 1000 A.

[0023] In at least one embodiment, at least one high-voltage bypass device is triggered by an overvoltage exceeding twice or more the rated voltage of the switching unit.

[0024] In at least one embodiment, at least one high-voltage bypass device has an activation time of less than 10 ms for bypassing at least one switching unit under overvoltage conditions.

[0025] In at least one embodiment, at least one high-voltage bypass device is configured to bypass at least one switching unit for more than 24 hours, preferably more than 168 hours.

[0026] These characteristics enable the converter to be used in typical voltage, current, overvoltage conditions, switching time, and running time conditions encountered in high-voltage installations.

[0027] According to a third aspect, an operating method for a high-voltage bypass device is disclosed. The method includes:

[0028] Triggering elements connected to the two terminals of a bypass device under overvoltage conditions, particularly by generating heat through spark or ohmic heating;

[0029] In response to triggering the triggering element, at least partially disrupting the gate of the bypass device, particularly through melting, evaporation, or combustion, thereby releasing a conductive, flowable material; and

[0030] The cavity of the bypass device is at least partially filled with a conductive, flowable material, thereby forming a permanent electrical path between the two terminals of the bypass device.

[0031] The steps of the third aspect realize a simple mechanism that does not require any external control and thus reliably bypasses multiple parts of the high-voltage device.

[0032] This disclosure includes several aspects of high-voltage apparatus. Even if a particular feature is not explicitly mentioned in the context of a specific aspect, each feature described in relation to an aspect is disclosed herein with respect to other aspects. Attached Figure Description

[0033] The accompanying drawings are included to provide further understanding. In the drawings, elements with the same structure and / or function may be denoted by the same reference numerals. It should be understood that the embodiments shown in the drawings are illustrative and not necessarily drawn to scale.

[0034] Figures 1A to 1C A schematic cross-section of the first high-voltage bypass device is shown before, during, and after an overvoltage condition occurs.

[0035] Figure 2A , 2B Figures 2 and 2C show schematic cross-sections of the second high-voltage bypass device before, during, and after an overvoltage condition occurs.

[0036] Figure 3 A schematic circuit diagram of a portion of a voltage source converter, including a single switching unit, is shown.

[0037] Figure 4 A schematic circuit diagram of a portion of a modular multi-cell converter, including multiple switching units, is shown.

[0038] Figures 5A to 5C A schematic cross-section of the third high-voltage bypass device is shown before, during, and after an overvoltage condition occurs.

[0039] Figures 6A to 6C The different cross sections of the fourth high-voltage bypass device are shown before and after the overvoltage condition occurs.

[0040] Figure 7 The method of operating a high-voltage bypass device is illustrated schematically. Detailed Implementation

[0041] Figure 1A The functional components of the first bypass device 10 are shown schematically. The bypass device 10 includes a first terminal 11 and a second terminal 12 for connecting the bypass device 10 to a corresponding electrical connection of the device to be bypassed. For example, the bypass device 10 may be connected in parallel with a switching device (such as an IGBT) and / or a mechanical bypass switch so that it can be short-circuited in the event of a failure of the corresponding device.

[0042] Two terminals 11 and 12 are electrically isolated from each other by multiple components such as an insulating housing, thereby forming a cavity 13. Multiple portions of the first terminal 11 form a first electrode 14 protruding into the cavity 13. Similarly, multiple portions of the second terminal 12 form a second electrode 15 protruding into the cavity 13. The first electrode 14 and the second electrode 15 together form a spark gap 16 therebetween. The spark gap 16 serves as a triggering element for a first bypass device 10 and is triggered in the event of an overvoltage condition between the first terminal 11 and the second terminal 12. The overvoltage value that triggers the bypass device 10 is determined by the shape and distance between the two electrodes 14 and 15 and the potential gas filling the cavity 13. According to one embodiment, a protective gas or vacuum may be used to fill the cavity 13. For example, a voltage of 5 kV may trigger an arc in the spark gap 16.

[0043] exist Figure 1A In the bypass device 10 shown, the second terminal 12 forms the outer wall of a reservoir 17 filled with a conductive flowable material 18. In the illustrated embodiment, the conductive flowable material 18 is disposed at the center of the second terminal 12, directly above the first electrode 14 at the mounting position of the bypass device 10. The channel between the reservoir 17 and the cavity 13 below it is sealed by a gate 19. The gate 19 is disposed near the second electrode 15. For example, as shown, a film formed of a thin polymer material with a low melting point can be used to seal the conductive flowable material 18 within the reservoir 17.

[0044] exist Figure 1B In the illustrated case, an overvoltage condition occurs between the first terminal 11 and the second terminal 12. Consequently, a spark 20 forms between the first terminal 14 and the second electrode 15. The heat associated with the spark 20, such as from heated plasma, melts or otherwise damages at least a portion of the gate 19. Figures 1A to 1C In the illustrated embodiment, the membrane separating the reservoir 17 and the cavity 13 is substantially completely destroyed. In another embodiment, only a portion of the gate 19 may be destroyed, thereby triggering a mechanical breakdown of the seal between the reservoir 17 and the cavity 13. For example, a fuse made of polymer material may be broken by a spark 20, releasing a spring-loaded separator (not shown). Consequently, conductive flowable material 18 flows into the cavity 13 under gravity.

[0045] exist Figure 1C In the illustrated case, the lower portion of cavity 13 is filled with a conductive, flowable material 18, such that the conductive, flowable material 18 contacts both the first electrode 14 and the second electrode 15. Therefore, a permanent conductive path 21 is formed between the first terminal 11 and the second terminal 12. Unlike high-power semiconductor switching devices, the conductive path 21 does not require active cooling.

[0046] For example, metallic materials that are liquid at atmospheric pressure and room temperature (20°C) can be used. Examples include mercury and certain gallium-based metal alloys, such as gallium, indium, and tin alloys (also known as Galistan), which have melting points of approximately -39°C and -19°C, respectively, and exhibit low electrical resistance. Depending on the operating conditions, if the high-voltage bypass device 10 is installed in another part of the converter or high-voltage electrical installation and operates continuously above the melting point of the corresponding metal, metals or metal alloys with slightly higher melting points, such as gallium with a melting point of approximately 30°C, can also be used.

[0047] As another example, powdered or granular materials can be used as conductive flowable materials 18. For example, relatively small copper particles with particle sizes in the micrometer range can be used to form electrical pathways 21. If relatively fine powder is used, the high current flowing through the bypass device may in turn melt a portion of the powder material filling the gaps between the electrodes, forming a conductive path 20 with lower resistance compared to the original powder.

[0048] Figures 2A to 2C Another embodiment of the second high-voltage bypass device 10 is shown. According to... Figures 2A to 2C Most components of the high-voltage bypass device 10 correspond to Figures 1A to 1C The corresponding components of the high-voltage bypass device 10 are shown. Therefore, only the differences are described here.

[0049] Unlike the first embodiment, in Figure 2A In the second high-voltage bypass device 10 shown, the first and second terminals 11 and 12 form opposing sidewalls of the bypass device 10. Therefore, the first electrode 14 and the second electrode 15 protrude from their respective sidewalls toward the center of the cavity 13. The bottom of the cavity 13 is formed by an insulating bottom 22. A flowable material 18 is disposed in a reservoir 17 formed as an insulating top 23 of the bypass device 10. Depending on the flowable material 18 used, the reservoir 17 can be opened at the top and sealed with a cap (not shown).

[0050] As previously described, the gate 19 is positioned above and close to the straight line between the two electrodes 13 and 14 that form the spark gap 16. Figure 1B As shown, a spark 20 is generated under an overvoltage condition between the first terminal 11 and the second terminal 12. Therefore, the gate 19 will be partially or completely destroyed, and the flowable material 18 will partially or completely fill the cavity 13 arranged below the reservoir 17. Figure 2C As shown in the specific embodiment, the conductive and flowable material 18 substantially fills the entire cavity 13.

[0051] Figure 3A portion of a high-voltage device including the bypass device 10 according to this disclosure is shown. Specifically, a single switching unit 30 that can be used in a voltage source converter (such as a modular multi-cell converter (MMC) described later) is depicted.

[0052] Figure 3 The switch unit 30 shown includes a half-bridge 31, which is composed of... Figure 3 The capacitor in the diagram represents a voltage source 32, and two IGBTs 33a and 33b are connected in series between the two terminals of the voltage source 32. Each IGBT 33a and 33b also has corresponding diodes 34a and 34b, which conduct current in opposite directions. This can be in the form of integrated diodes or external diodes.

[0053] Between the two IGBTs, an electrical contact 35 is formed, which can be used, for example, to output the voltage generated by the half-bridge 31 to a high-voltage device (not shown).

[0054] exist Figure 3 If the lower IGBT 33a of the half-bridge 31 shown cannot be activated (i.e. closed), the entire switching unit 30 will permanently disconnect the electrical path between the electrical reference contact 36 and the electrical contact 35. Therefore, any other part of the converter or electrical device including the switching unit 30 will block any current to be transmitted.

[0055] To avoid this situation, according to Figure 3 Bypass device 10 (as mentioned above) Figures 1A to 2C The bypass device (described in detail) is mounted in parallel with the first IGBT 33a. As described above, if the lower IGBT 33a cannot be activated, i.e., by providing a corresponding gate voltage to its control gate, an overvoltage condition will occur between the electrical contact 35 and the reference contact 36. Therefore, the spark 20 will be triggered within the spark gap 16 of the bypass device 10, thereby releasing the conductive flowable material 18 to form a permanent conductive path 21 through the bypass device 10 (see also...). Figure 7 (Steps S1 to S5). This effectively shortens the switching unit 30 and maintains the electrical path between the reference contact 36 and the electrical contact 35. Current can flow freely through unit 30, allowing the entire converter to continue operating.

[0056] As described above, the gate 19 can be formed of a polymer material that is substantially destroyed under overvoltage conditions. Therefore, the electrical bypass device 10 can be triggered only once. Thus, it can also be referred to as a sacrificial component, particularly a sacrificial spark short-circuit device.

[0057] While the setup of bypass device 10 is relatively simple and therefore inexpensive to manufacture, it may be desirable to implement an additional method of bypassing the first IGBT 33a in a controlled manner. Therefore, in Figure 3 In the illustrated embodiment, an additional mechanical bypass switch 37 may be connected in parallel to the first IGBT 33a and the bypass device 10. The mechanical bypass switch 37 may be controlled by a corresponding control circuit (not shown). If the control circuit determines that the switching unit 30 should be deactivated or the IGBT 33a cannot be successfully activated, the mechanical bypass switch 37 may be closed to establish an electrical path between the reference contact 36 and the electrical contact 35.

[0058] Preferably, the mechanical bypass switch 37 is activated by the control circuit before a spark 20 is formed in the bypass device 10. In this configuration, the sacrificial bypass device 10 is activated only when both the first IGBT 33a and the mechanical bypass switch 37 fail simultaneously. In practice, the switching unit 30 or IGBT 33a will have a specific rated voltage, such as 1kV or 3kV. In the event of an IGBT failure, the mechanical bypass switch 37 will be triggered by the monitoring circuit. The gap between the first electrode 14 and the second electrode 15 of the bypass device 10 can be configured to trigger only when the voltage potential between the electrical contact 35 and the reference contact 36 exceeds twice the rated voltage of the IGBT 33a. In operation, this may occur within 10ms of a mechanical bypass switch 37 failure.

[0059] Figure 4 This diagram illustrates how multiple switching units 30 can be combined to form a modular multi-unit converter 40. In the depicted embodiment, the modular multi-unit converter 40 includes a total of four switching units 30a to 30d connected in series. Each switching unit's reference contact is connected to the electrical contact of the preceding switching unit. The reference contact 36 of the first switching unit 30a is connected to an electrical reference potential, such as an external voltage provided by a high-voltage transmission line. The electrical contact 35 of the last switching unit 30d can then be connected to the output of the MMC 40, such as a direct current (DC) network, into which energy from a high-voltage alternating current (HVAC) network will be supplied.

[0060] Each switching unit 30a to 30d of the MMC 40 may include one of the bypass devices 10 as described above. For clarity, only a single bypass device 10 for the second switching unit 30b is shown. If one of the IGBTs 33 in any of the switching units 30 fails, electrical transfer from the external reference potential to the output line is still possible via the corresponding bypass device 10. Although a failure, for example, in the second switching unit 30b will negatively impact the performance of the MMC 40, it can still remain operational, thus allowing for controlled shutdown or repair of the faulty portion of the converter.

[0061] Figures 5A to 5CAnother embodiment of the third high-voltage bypass device 10 is shown. According to... Figures 2A to 2C Most components of the high-voltage bypass device 10 correspond to Figures 1A to 1C and Figures 2A to 2C The corresponding components of the high-voltage bypass device 10 are shown. Therefore, only the differences are described here.

[0062] Unlike the first and second embodiments, in the third high-voltage bypass device 10, a varistor 50 is used as the trigger element. The varistor 50 is placed in the central portion of the cavity 13, below the gate 19 and physically separated from the gate 19. Figure 5A As shown, the terminals of the varistor 50 are electrically connected to the (external) first and second terminals 11 and 12 of the bypass device 10, respectively. In the depicted embodiment, the terminals of the varistor 50 are in direct contact with the first electrode 14 and the second electrode 15, respectively, forming corresponding conductive portions of the sidewall 51 of the cavity 13. Electrodes 14 and 15 are also electrically connected to or integrally formed with the first terminal 11 and the second terminal 12.

[0063] As is well known, the resistance of a varistor changes depending on the voltage across its terminals. A varistor is a ceramic component with non-linear electrical characteristics. Generally, a varistor, also known as a surge arrester, remains non-conductive or at high ohms during normal operation when the voltage across its terminals is well below a threshold voltage (also known as a clamping voltage). At voltages above this threshold (also known as a switching voltage), the varistor becomes conductive. In standard applications, such as overvoltage protection, varistors are used to absorb a given maximum energy. However, if the energy exceeds this maximum value, a severe temperature rise or even thermal runaway can occur.

[0064] In the third embodiment, the varistor 50 is intentionally pushed to thermal runaway, causing a large amount of heat to be generated in the varistor 50. Therefore, when an overvoltage condition occurs between terminals 11 and 12, the varistor 50 heats up and triggers the gate 19 (e.g., by melting or evaporating it).

[0065] As previously described, the gate 19 is positioned above and close to the trigger element formed by the varistor 50. Figure 5B As shown, in the event of an overvoltage condition between the first terminal 11 and the second terminal 12, heat 52 will be generated and dissipated. Therefore, the gate 19 will be partially or completely destroyed, and the flowable material 18 will partially or completely fill the cavity 13 located below the reservoir 17. Figure 5C As shown in the specific embodiment, the conductive and flowable material 18 substantially fills the entire cavity 13.

[0066] exist Figure 5CIn the illustrated case, the varistor 50 is effectively bypassed by the conductive, flowable material 18, which directly contacts electrodes 14 and 15, forming corresponding conductive portions of the sidewall 51 of the cavity 13. The varistor 50 itself may be partially or completely destroyed by thermal runaway. However, this is not significant for the conductive, flowable material 18 to form an electrical bypass.

[0067] Figures 6A to 6C Another embodiment of the fourth high-voltage bypass device 10 is shown. According to... Figures 6A to 6C Most components of the high-voltage bypass device 10 correspond to Figures 5A to 5C The corresponding components of the high-voltage bypass device 10 are shown. Therefore, only the differences are described here.

[0068] As previously described, the varistor 50 is used as a trigger element in the fourth high-voltage bypass device 10. In contrast to the previous embodiment, the varistor 50 is arranged in direct thermal contact with the gate 19. Therefore, the heat generated by the varistor 50 in response to an overvoltage condition acts directly on the gate material. This typically results in a fast response time. Furthermore, this configuration may be useful when the cavity is filled with a vacuum or a protective gas with poor thermal properties.

[0069] like Figure 6B As shown in the cross-section, the varistor 50 does not extend to the full depth of the cavity 13, leaving an open area 53 between the varistor 50 and the front isolation wall 54 and / or the rear isolation wall 55 before the gate 19 is released.

[0070] like Figure 6C As shown in the cross-section, when the varistor 50 is triggered, the gate 19 is at least partially destroyed, and the flowable material 18 passes through the open area 53 to partially or completely fill the cavity 13.

[0071] Figure 7 The steps that occur during the activation of the bypass device 10 are illustrated again in a schematic manner.

[0072] In the first step S1, an overvoltage occurs across the bypass device 10. Note that the overvoltage may occur automatically due to a failure of another component, such as the failure of the mechanical bypass switch to activate.

[0073] In step S2, the triggering element connected to the two terminals 11 and 12 carrying the overvoltage is triggered. For example, the triggering element may generate heat in response to the overvoltage condition. For example, if the voltage potential between the first terminal 11 and the second terminal 12 exceeds a predetermined voltage, a spark 20 will be generated between the two electrodes 14 and 15. Alternatively, a thermal runaway state in the varistor 50 or similar electrical component may be used to generate heat, for example, by ohmic heating.

[0074] In step S3, in response to the triggering event of step S2, a gate 19 is released that separates the flowable material 18 from the corresponding cavity 13. For example, the gate 19, which includes a thermistor material, can release heat generated by an electric arc (i.e., a spark 20) ​​or thermal runaway conduction from a triggering element. For example, the generation of spark 20 may lead to the localization of thermal plasma, which in turn may melt, evaporate, or burn the polymer material, thereby releasing the gate 19. Similarly, thermal runaway of the varistor 50 also releases enough heat to melt, evaporate, or burn the polymer material.

[0075] In the absence of gate 19, in step S4, conductive flowable material 18 will fill the cavity 13 arranged on the other side of the damaged gate 19. This may occur naturally due to gravity acting on the flowable material 18, or it may be assisted or executed by external forces (such as a spring loading mechanism).

[0076] Once the conductive and flowable material 18 fills the space between the first terminal 11 and the second terminal 12 to a sufficient extent, for example by contacting the first electrode 14 and the second electrode 15, a solid or liquid conductive path 21 is formed.

[0077] While this disclosure may be made in various modifications and alternatives, its details have been shown by way of example in the accompanying drawings and will be described in detail. However, it should be understood that this disclosure is not intended to be limited to the specific embodiments described. Rather, it is intended to cover all modifications, equivalents, and alternatives that fall within the scope of the disclosure as defined in the appended claims.

[0078] For example, although the present invention has been described with respect to half-bridge 31 and MMC converter 40, it can also be applied to full-bridge and / or other types of power converters.

[0079] Figure Labels

[0080] 10 Bypass devices

[0081] 11 First terminal

[0082] 12 Second terminal

[0083] 13. Cavity

[0084] 14 First Electrode

[0085] 15 Second Electrode

[0086] 16 Spark Gap

[0087] 17. Liquid reservoir

[0088] 18. Flowable materials

[0089] 19. Gate

[0090] 20 Sparks

[0091] 21 Conductive Path

[0092] 22 Insulating bottom

[0093] 23 Insulating top

[0094] 30 Switching Units

[0095] 31 Half Bridge

[0096] 32 Voltage Source

[0097] 33a / b IGBT

[0098] 34a / b Body Diode

[0099] 35 electrical contacts

[0100] 36 Reference Contacts

[0101] 37 Mechanical bypass switch

[0102] 40 Modular Multi-Unit Converter

[0103] 50 varistor

[0104] 51. Conductive portion of the sidewall

[0105] 52 calories

[0106] 53 Open Areas

[0107] 54. Isolation Anterior Wall

[0108] 55 Isolation Back Wall

Claims

1. A high-voltage bypass device (10), comprising: Cavity (13); A trigger element is arranged in the cavity (13) and connected to the first terminal (11) and the second terminal (12) of the high voltage bypass device (10). The reservoir (17) is filled with a conductive and flowable material (18); and A gate (19) separates the cavity (13) from the reservoir (17), wherein the gate (19) is configured to open a channel between the cavity (13) and the reservoir when the triggering element is triggered by an overvoltage condition, such that the conductive flowable material (18) at least partially fills the cavity (13) to form a conductive path (21) from the first terminal (11) to the second terminal (12). The triggering element includes at least one of the following: A first electrode (14) connected to the first terminal (11) and a second electrode (15) connected to the second terminal (12), the first electrode (14) and the second electrode (15) extending into the cavity (13) and forming a spark gap (16) between the first electrode (14) and the second electrode (15); and / or A varistor (50) is connected between the first terminal (11) and the second terminal (12).

2. The device (10) according to claim 1, wherein, The conductive and flowable material (18) includes at least one of the following: Liquid, powder, and granular materials; and / or Metal or metal alloy.

3. The device according to claim 2, wherein, The metal or metal alloy is gallium, gallium indium tin alloy, mercury, aluminum, or copper.

4. The device (10) according to claim 1, wherein, The triggering element is configured to generate heat (52) under overvoltage conditions, and the gate (19) comprises a thermosensitive material that is at least partially destroyed by one of melting, evaporation, or combustion.

5. The device (10) according to claim 4, wherein, The thermosensitive material is a polymer material.

6. The device (10) according to claim 4, wherein, The gate (19) includes one of the following: a thermal membrane separating the cavity (13) and the reservoir (17), or a thermal trigger coupled to a spring-loaded separator separating the cavity (13) and the reservoir (17).

7. The device (10) according to claim 1, wherein, The reservoir (17) is positioned above the cavity (13) at the mounting location of the device (10) such that when the triggering element is triggered, the conductive flowable material (18) is released by gravity.

8. The device (10) according to claim 1. in, The triggering element includes a first electrode (14) connected to the first terminal (11) and a second electrode (15) connected to the second terminal (12), the first electrode (14) and the second electrode (15) forming a spark gap (16) and being arranged as follows: The first electrode (14) is arranged at the bottom of the cavity (13) and protrudes upward, and the second electrode (15) is arranged at the top of the cavity near the gate (19) and protrudes downward; and / or The first electrode (14) is arranged on the first wall of the cavity (13) and protrudes toward the opposite second wall of the cavity (13), and the second electrode (15) is arranged on the second wall of the cavity (13) and protrudes toward the first wall of the cavity (13), wherein the direct path between the first and second electrodes (14, 15) is close to the gate (19). Alternatively, the triggering element may include a varistor (50) connected between the first terminal (11) and the second terminal (12) and arranged as follows: The varistor (50) is arranged in the central portion of the cavity (13) below the gate (19), and / or The varistor (50) is arranged to be in direct thermal contact with the gate (19).

9. The device (10) according to claim 1, wherein, Before the triggering element is triggered, the cavity (13) is filled with a vacuum or a protective gas.

10. The device (10) according to claim 1, wherein, The conductive and flowable material (18) is configured to form a permanent electrical path between the first terminal (11) and the second terminal (12) after the triggering element is triggered.

11. The device (10) according to claim 10, wherein, The conductive flowable material (18) is configured to form a permanent electrical path between the first terminal (11) and the second terminal (12) after the triggering element is triggered by one of the following methods: flooding the cavity (13) with a conductive liquid; or by contacting the first electrode (14) and the second electrode (15) extending into or defining the cavity (13) with a particulate conductive medium.

12. A voltage source converter, comprising: At least one switching unit (30) is configured to switch high voltage; and At least one high-voltage bypass device (10) according to any one of claims 1 to 11 is configured to bypass the at least one switching unit (30) in the event of a fault.

13. The voltage source converter according to claim 12, wherein, The voltage source converter is a modular multi-unit converter.

14. The voltage source converter according to claim 12, wherein, The switching unit (30) includes at least one power semiconductor switching device, and the high-voltage bypass device (10) is connected in parallel with the at least one power semiconductor switching device.

15. The voltage source converter according to claim 14, wherein, The at least one power semiconductor switching device is an IGBT (33a).

16. The voltage source converter according to any one of claims 12 to 15, wherein, The switching unit (30) further includes at least one mechanical bypass switch (37) connected in parallel with the at least one power semiconductor switching device and the high voltage bypass device (10).

17. The voltage source converter according to any one of claims 12 to 15, wherein, The rated voltage of the at least one switching unit (30) exceeds 1kV, and / or the rated current exceeds 100A.

18. The voltage source converter according to claim 17, wherein, The rated voltage of the at least one switching unit (30) exceeds 3kV, and / or the rated current exceeds 1000A.

19. The voltage source converter according to any one of claims 12 to 15, wherein: The at least one high-voltage bypass device (10) is triggered by an overvoltage exceeding twice or more the rated voltage of the switching unit (30); The at least one high-voltage bypass device (10) has an activation time of less than 10 ms, used to bypass the at least one switching unit (30) under overvoltage conditions; and / or The at least one high-voltage bypass device (10) is configured to bypass the at least one switching unit (30) for a period of time exceeding 24 hours.

20. The voltage source converter according to claim 19, wherein, The at least one high-voltage bypass device (10) is configured to bypass the at least one switching unit (30) for a period of more than 168 hours.

21. An operating method for a high-voltage bypass device (10), comprising: Under overvoltage conditions, the triggering element connected to the first terminal (11) and the second terminal (12) of the bypass device (10) is triggered; In response to triggering the triggering element, at least partially disrupting the gate (19) of the bypass device (10) thereby releasing the conductive flowable material (18). as well as The cavity (13) of the bypass device is at least partially filled with the conductive and flowable material (18), thereby forming a permanent electrical path between the first terminal (11) and the second terminal (12) of the bypass device (10). The triggering element includes at least one of the following: A first electrode (14) connected to the first terminal (11) and a second electrode (15) connected to the second terminal (12), the first electrode (14) and the second electrode (15) extending into the cavity (13) and forming a spark gap (16) between the first electrode (14) and the second electrode (15); and / or A varistor (50) is connected between the first terminal (11) and the second terminal (12).

22. The operating method according to claim 21, wherein, The triggering element that triggers the first terminal (11) and the second terminal (12) of the bypass device (10) under overvoltage conditions includes: Under overvoltage conditions, heat (52) is generated by spark or ohmic heating, triggering the triggering element connected to the first terminal (11) and the second terminal (12) of the bypass device (10).

23. The operating method according to claim 21, wherein, The gate (19) that at least partially disrupts the bypass device (10) includes: The gate (19) of the bypass device (10) is at least partially destroyed by melting, evaporation, or burning.

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