Electrical system for use in a high voltage direct current multi-terminal switching station

Abstract

An electrical system (300) comprising: a first busbar (302a); a second busbar (302b); a resistor module (306) comprising one or more resistors, the resistor module (306) being electrically coupled between the first busbar (302a) and the second busbar (302b); a first switching element (307) being electrically coupled between the first busbar (302a) and the second busbar (302b), the first switching element (307) being in series with the resistor module (306); and a plurality of power transmission mediums (304); wherein each power transmission medium (304) of the plurality of power transmission mediums (304) is electrically coupled to the first busbar (302a) via a respective second switching element (308); and each power transmission medium (304) of the plurality of power transmission mediums (304) is electrically coupled to the second busbar (302b) via a respective third switching element (310).

Description

Technical Field

[0001] This article generally deals with electrical systems used in high-voltage direct current (HVDC) multi-terminal switch stations (MTSS). Background Technology

[0002] In recent years, the development of high-voltage direct current (HVDC) transmission systems has increasingly shifted towards multi-terminal configurations, where multiple HVDC schemes are interconnected. Such multi-terminal HVDC systems typically require the implementation of a multi-terminal switch station (MTSS), which serves as a hub for selectively connecting or disconnecting individual HVDC schemes.

[0003] When integrating a power transmission medium (such as an HVDC cable) into an active system, especially when the medium is pre-grounded, it is typically necessary to charge it before it can be connected. To control inrush current during this charging process, a pre-insertion resistor (PIR) is usually employed. The PIR limits current flow when the power transmission medium is charged from the MTSS. Similarly, when an HVDC converter is online and connected to the MTSS, charging via a PIR is typically performed, even where there is minimal distance between the HVDC converter and the switching station.

[0004] In scenarios where the power transmission medium must be de-energized, such as during maintenance or fault clearing, the power transmission medium must be safely discharged. While this function is typically performed by a dynamic braking system (DBS), there are situations where a DBS cannot be utilized. In such cases, a PIR used for charging can also be used for discharging, provided it is properly rated and equipped with the necessary grounding switch to handle the discharge operation. Summary of the Invention

[0005] HVDC schemes are being considered for use in urban areas and for connection to offshore wind farms that may only be accessible via floating offshore platforms. Therefore, the weight and volume of converter stations and switchyards may be subject to more stringent limitations than currently available. The inventors have recognized that this may lead to the use of gas-insulated switchgear (GIS) in some HVDC schemes, for example, instead of air-insulated switchgear (AIS). The inventors also recognize that the need to disperse heat generated during charging or discharging via PIR may prevent the inclusion of PIR devices within the GIS itself.

[0006] The goal is to provide an electrical system that mitigates these problems, such as an MTSS.

[0007] According to a first aspect, an electrical system is provided, comprising: a first busbar; a second busbar; a resistor module including one or more resistors electrically coupled between the first busbar and the second busbar; a first switching element electrically coupled between the first busbar and the second busbar, the first switching element being connected in series with the resistor module; and a plurality of power transmission media. Each of the plurality of power transmission media is electrically coupled to the first busbar via a corresponding second switching element. Each of the plurality of power transmission media is electrically coupled to the second busbar via a corresponding third switching element.

[0008] The resistor module may include: a plurality of resistors; and a plurality of switching elements, each of the plurality of switching elements being electrically coupled to one or more of the resistors. The plurality of resistors may be selectively connected in series or in parallel via the plurality of switching elements.

[0009] The resistor module may include: a first terminal electrically coupled to the first bus; and a second terminal electrically coupled to the second bus. The electrical system may also include a fourth switching element electrically coupled to the first terminal. The first terminal may be configured to be selectively connected to ground via the fourth switching element.

[0010] The resistor module may include: a first terminal electrically coupled to the first bus; and a second terminal electrically coupled to the second bus. The electrical system may also include a fifth switching element electrically coupled to the second terminal. The second terminal may be configured to be selectively connected to ground via the fifth switching element.

[0011] Each of the plurality of power transmission media may include a corresponding terminal electrically coupled to the first bus. The electrical system may also include a plurality of sixth switching elements. For each of the plurality of power transmission media, the terminal of that power transmission media may be configured to be selectively connected to ground via a corresponding sixth switching element.

[0012] The first busbar may include a first busbar terminal. The electrical system may also include a seventh switching element electrically coupled to the first busbar terminal. The first busbar terminal may be configured to be selectively connected to ground via the seventh switching element.

[0013] The electrical system may further include: an additional resistor module comprising one or more additional resistors electrically coupled between the first bus and the second bus; and an additional switching element electrically coupled between the first bus and the second bus, the additional switching element being connected in series with the additional resistor module.

[0014] The electrical system may also include a housing. The first busbar, the second busbar, each first switching element, and each second switching element may be encapsulated within the housing. The resistor module may be located outside the housing. The housing may accommodate a gas-insulated switchgear (GIS) system.

[0015] The electrical system may be a multi-terminal switch station (MTSS). The electrical system may be a high-voltage direct current (HVDC) MTSS.

[0016] In another aspect, a first method is provided for operating an electrical system of any of the foregoing aspects. The first method is used to charge a first power transmission medium among the plurality of power transmission media. The first method includes: opening a sixth switching element of the first power transmission medium; opening a fifth switching element; opening a fourth switching element; closing the first switching element; and closing a third switching element of the first power transmission medium, thereby charging the first power transmission medium via the resistor module.

[0017] The first method may further include: closing the second switching element of the first power transmission medium; opening the third switching element of the first power transmission medium; and opening the first switching element.

[0018] The first method may further include: closing the fourth switching element and / or closing the fifth switching element.

[0019] In another aspect, a second method is provided for operating an electrical system of any of the foregoing aspects. The second method is used to discharge a first power transmission medium among the plurality of power transmission media. The second method includes: closing the fourth switching element; isolating the first power transmission medium from the first bus and the second bus by opening the second and third switching elements of the first power transmission medium; opening the fifth switching element; and closing the third switching element of the first power transmission medium, thereby discharging the first power transmission medium to ground via the resistor module.

[0020] The second method may further include: closing the sixth switching element of the first power transmission medium; opening the third switching element of the first power transmission medium; and closing the fifth switching element.

[0021] In another aspect, a method for operating an electrical system of any of the foregoing aspects is provided, using a third switching element. The third method is used to electrically isolate a first power transmission medium of the plurality of power transmission media from the first bus and the second bus. The third method includes: opening the second switching element of the first power transmission medium; and opening the third switching element of the first power transmission medium.

[0022] In another aspect, a fourth method is provided for operating an electrical system according to any of the foregoing aspects. The fourth method is for electrically isolating the first busbar. The fourth method includes: opening each second switching element; opening each third switching element; and, while the second and third switching elements are open, closing the seventh switching element, thereby connecting the first busbar to ground.

[0023] It will be understood that specific features in different aspects share the technical effects and benefits of corresponding features in other aspects of the invention.

[0024] It will also be understood that the use of terms such as “first” and “second” is intended only to help distinguish similar features, and not to indicate the relative importance of one feature relative to another, unless otherwise stated.

[0025] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples, and alternatives set forth in the preceding paragraphs and claims and / or the following description and drawings, and in particular their individual features, may be employed independently or in any combination. That is, all embodiments and all features of any embodiment may be combined in any manner and / or combination unless such features are incompatible.

[0026] The present invention also provides a set of technical solutions, as follows: Technical Solution 1. An electrical system, comprising: First busbar; Second busbar; A resistor module comprising one or more resistors, the resistor module being electrically coupled between a first busbar and a second busbar; A first switching element, electrically coupled between the first bus and the second bus, is connected in series with the resistor module; and Multiple power transmission media; among which Each of the plurality of power transmission media is electrically coupled to the first bus via a corresponding second switching element; and Each of the plurality of power transmission media is electrically coupled to the second bus via a corresponding third switching element.

[0027] Technical Solution 2. The electrical system according to Technical Solution 1, wherein the resistor module comprises: Multiple resistors; and A plurality of switching elements, each of which is electrically coupled to one or more resistors in the resistor array; wherein The plurality of resistors may be selectively connected in series or in parallel via the plurality of switching elements.

[0028] Technical solution 3. The electrical system according to any of the foregoing technical solutions, wherein The resistor module includes: Electrically coupled to the first terminal of the first busbar; and Electrically coupled to the second terminal of the second busbar; The electrical system further includes a fourth switching element electrically coupled to the first terminal; and The first terminal is configured to be selectively connected to ground via the fourth switching element.

[0029] Technical Solution 4. The electrical system according to any of the foregoing technical solutions, wherein The resistor module includes: Electrically coupled to the first terminal of the first busbar; and Electrically coupled to the second terminal of the second busbar; The electrical system further includes a fifth switching element electrically coupled to the second terminal; and The second terminal is configured to be selectively connected to ground via the fifth switching element.

[0030] Technical Solution 5. The electrical system according to any of the foregoing technical solutions, wherein Each of the plurality of power transmission media includes a corresponding terminal electrically coupled to the first bus; The electrical system also includes multiple sixth switching elements; and For each of the plurality of power transmission media, the terminal of that power transmission media is configured to be selectively connected to ground via a corresponding sixth switching element.

[0031] Technical Solution 6. The electrical system according to any of the foregoing technical solutions, wherein The first busbar includes first busbar terminals; The electrical system also includes a seventh switching element electrically coupled to the first bus terminal; and The first bus terminal is configured to be selectively connected to ground via the seventh switching element.

[0032] Technical Solution 7. The electrical system according to any of the foregoing technical solutions further includes: An additional resistor module comprising one or more additional resistors, the additional resistor module being electrically coupled between the first bus and the second bus; and An additional switching element, electrically coupled between the first bus and a separate second bus, is connected in series with the additional resistor module.

[0033] Technical Solution 8. The electrical system according to any of the foregoing technical solutions further includes: The outer shell; in which The first busbar, the second busbar, each first switching element, and each second switching element are encapsulated in the housing; and The resistor module is located outside the housing.

[0034] Technical Solution 9. The electrical system according to Technical Solution 8, wherein the housing houses a gas-insulated switchgear (GIS) system.

[0035] Technical Solution 10. The electrical system according to any of the foregoing technical solutions, wherein the electrical system is a multi-terminal switch station (MTSS).

[0036] Technical Solution 11. The electrical system according to Technical Solution 10, wherein the electrical system is a high-voltage direct current (HVDC) MTSS.

[0037] Technical Solution 12. A method for operating an electrical system according to any of the foregoing technical solutions, subordinate to technical solutions 3, 4, and 5, the method being used to charge a first power transmission medium among the plurality of power transmission media, the method comprising: Turn on the sixth switching element of the first power transmission medium; Turn on the fifth switching element; Turn on the fourth switching element; Close the first switching element; and The third switching element of the first power transmission medium is closed, thereby charging the first power transmission medium via the resistor module.

[0038] Technical Solution 13. A method for operating an electrical system according to any of the foregoing technical solutions, subordinate to technical solutions 3 and 4, the method being used to discharge a first power transmission medium among the plurality of power transmission media, the method comprising: Close the fourth switching element; By opening the second and third switching elements of the first power transmission medium, the first power transmission medium is isolated from the first bus and the second bus; Open the fifth switching element; and The third switching element of the first power transmission medium is closed, thereby discharging the first power transmission medium to ground via the resistor module.

[0039] Technical Solution 14. A method for operating an electrical system according to any one of technical solutions 1 to 11, the method being used to electrically isolate a first power transmission medium of a plurality of power transmission media from a first bus and a second bus, the method comprising: The second switching element that turns on the first power transmission medium; and The third switching element of the first power transmission medium is turned on.

[0040] Technical Solution 15. A method for operating the electrical system according to Technical Solution 6 or any claim relating to Technical Solution 6, the method for electrically isolating the first busbar, the method comprising: Turn on each second switching element; Open each third switching element; and With the second and third switching elements open, the seventh switching element is closed, thereby connecting the first busbar to ground. Attached Figure Description

[0041] Embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram illustrating a first example of a conventional electrical system; Figure 2 This is a schematic diagram illustrating a second example of a conventional electrical system; Figure 3 The electrical system for use in HVDC MTSS is shown; Figure 4 The first table illustrates the bay discharge process used in electrical systems; Figure 5 A second table illustrating the interval charging process for an electrical system is shown; Figure 6 The third table illustrates the isolation process used in electrical systems; and Figure 7 The fourth table illustrates the busbar isolation process used in electrical systems. Detailed Implementation

[0042] Figure 1 This is a schematic diagram illustrating a first example of a conventional electrical system 100 for use in an MTSS. The first electrical system 100 is useful in understanding the invention. Further details regarding the first electrical system 100 can be found in... SHE Transmission, D15.1 Recommendations for Specifying DC GIS Systems, PROMOTioN– Progress on Meshed HVDC Offshore, 2018 The content is found here and referenced.

[0043] In this example, the first electrical system 100 includes two buses, namely a first bus 102a for the positive terminal of the system and a second bus 102b for the negative terminal of the system.

[0044] The first electrical system 100 also includes a plurality of power transmission media 104a, 104b (e.g., feeders for HVDC converters or HVDC cables). Each of the power transmission media 104a, 104b is coupled to a first or second bus 102a, 102b via a corresponding PIR 106a, 106b, a corresponding first switching element 108a, 108b, and a corresponding second switching element 110a, 110b.

[0045] For each power transmission medium 104a, 104b, a corresponding first switching element 108a, 108b is electrically coupled in series between that power transmission medium 104a, 104b and the bus 102a, 102b to which that power transmission medium 104a, 104b is coupled. For each power transmission medium 104a, 104b, the corresponding first switching element 108a, 108b is arranged to switchably connect that power transmission medium 104a, 104b to or disconnect it from the bus 102a, 102b to which that power transmission medium 104a, 104b is coupled.

[0046] For each power transmission medium 104a, 104b, a corresponding PIR 106a, 106b is electrically coupled in series between that power transmission medium 104a, 104b and the bus 102a, 102b to which that power transmission medium 104a, 104b is coupled. Each PIR 106a, 106b is arranged in parallel with a corresponding switching element of the second switching elements 110a, 110b. The second switching elements 110a, 110b are arranged to switchably bypass PIR 106a, 106b, or PIR 106a, 106b are connected in series between the power transmission medium 104a, 104b and the bus 102a, 102b.

[0047] In this example, the first example electrical system 100 also includes a plurality of grounding switches 112a, 112b. A corresponding pair of grounding switches 112a, 112b is coupled to each PIR 106a, 106b, one on either side of that PIR 106a, 106b. Each grounding switch 112a, 112b is arranged to switchably connect or disconnect the terminals of the PIR 106a, 106b to which it is connected. The grounding switches 112a, 112b can be used both to allow safe maintenance of the PIRs 106a, 106b when the MTSS operates at high voltage with the hub buses 102a, 102b, and to provide a grounding circuit to discharge the power transmission media 104a, 104b via the PIRs 106a, 106b.

[0048] Figure 2 This is a schematic diagram illustrating a second example of a conventional electrical system 200 for use in an MTSS. The second electrical system 200 is useful in understanding the invention.

[0049] In this example, the second electrical system 200 includes a bus 202 and a plurality of power transmission media 204 (e.g., feeders for an HVDC converter or HVDC cables). Each of the power transmission media 204 is coupled to the bus 202 via a corresponding PIR 206, a corresponding first switching element 208, a corresponding second switching element 110, and a corresponding third switching element 211.

[0050] The second electrical system 200 has a similar configuration to the first electrical system 100.

[0051] For each power transmission medium 204, a corresponding first switching element 208 is electrically coupled in series between that power transmission medium 204 and the bus 202. For each power transmission medium 204, the corresponding first switching element 208 is arranged to switchably connect that power transmission medium 204 to or disconnect it from the bus 202. In this example, the first switching element 208 is connected in series between the bus 202 and the second switching element 210.

[0052] For each power transmission medium 204, a corresponding PIR 206 is electrically coupled in series between that power transmission medium 204 and bus 202. Each PIR 206 is arranged in parallel with a corresponding switching element in the second switching element 210. The second switching element 210 is arranged to either switchably bypass the PIR 206 or connect the PIR 206 in series between the power transmission medium 204 and bus 202. In this example, the second switching element 210 is connected in series between the first switching element 208 and the third switching element 211.

[0053] For each power transmission medium 204, a corresponding third switching element 211 is electrically coupled in series between that power transmission medium 204 and the bus 202. In this example, the third switching element 211 is connected in series between the second switching element 210 and the power transmission medium 204. For safety during PIR maintenance, the third switching element 211 and the first switching element 208 can be used to electrically isolate the PIR 206 connected between them from the bus 202 and the power transmission medium 204.

[0054] In this example, the second example electrical system 200 also includes a plurality of grounding switches 212a, 212b. A corresponding pair of grounding switches 212a, 212b are coupled to each of the second switching elements 210, one on each side of the second switching element 210. Specifically, the first grounding switch 212a is connected to a first terminal on a first side of the second switching element 210, and the second grounding switch 212b is connected to a second terminal on a second side of the second switching element 210. The first grounding switch 212a is located on the same side of the second switching element 210 as the first switching element 208. The second grounding switch 212b is located on the same side of the second switching element 210 as the third switching element 211. Each grounding switch 212a, 212b is arranged to switchably connect or disconnect the terminal of the second switching element 210 to which it is connected.

[0055] In this example, the second electrical system 200 is implemented in a GIS application. Specifically, the second electrical system 200 includes a housing or enclosure 214 in which a pressurized gas (typically sulfur hexafluoride (SF6)) is used as the insulating medium. This tends to allow the HVDC system to manage high voltages within a confined space, which is particularly important in urban environments or offshore platforms.

[0056] In this example, the PIR 206 is located outside the housing 214, i.e., outside the GIS. This is to facilitate the dissipation of heat generated during charging or discharging via the PIR 206, which might be difficult or impossible if the PIR 206 were located inside the housing 214. In this example, the electrical connection connecting each PIR 206 to the circuitry of the second electrical system 200 passes through the wall of the housing 214 via a corresponding pair of sleeves 216. In other words, each PIR 206 is connected to the GIS using two sleeves 216. The sleeves can be insulated conductors used to interface the connection through the barrier (i.e., housing 214) to prevent or resist leakage or discharge. Bushings can be considered as interfaces or gaskets. The sleeves 216 can form an hermetically tight seal around the electrical connection passing through the wall of the housing 214, thereby preventing or resisting gas leakage from the GIS.

[0057] In this example, each power transmission medium 204 extends through the wall of the housing 214 via a corresponding additional bushing 218. The additional bushing 218 forms an hermetically tight seal around the power transmission medium 204 extending through the wall of the housing 214, thereby preventing or resisting gas leakage from the GIS.

[0058] In this example, a given power transmission medium 204 can be charged from bus 202 by closing its first switching element 208 and its third switching element 211, but opening its second switching element 210. This connects the power transmission medium 204 to bus 202 via PIR 206 to limit the current flow to the power transmission medium 204.

[0059] In this example, the given power transmission medium 204 can be discharged by: opening its first switching element 208 and its third switching element 211 to disconnect the power transmission medium 204 from the bus 202; opening the second switching element 210; closing the first grounding switch 212a; and then closing the third switching element 211 to ground the power transmission medium 204 via PIR 206.

[0060] The design of the second electrical system 200 uses a corresponding independent PIR 206 for each of the power transmission media 204. If a new feeder / power transmission media is added to station 200, a new PIR 206 will need to be included for that new power transmission media 204.

[0061] Furthermore, three grounding switches and three isolating switches can be implemented for each feeder to support the charging and discharging functionality of the circuit. Specifically, the second grounding switch 212b and the third switching element 211 can be used for isolation and maintenance. After discharging, the second grounding switch 212b can be closed to directly ground the feeder. Then, the third switching element 211 can be used to isolate the feeder from the interval (e.g., for PIR maintenance), and thus the additional grounding switch 213 closes to maintain a direct connection to the feeder.

[0062] In such Figure 2 In a GIS system such as the second electrical system 200 illustrated herein, at least two bushings are used to connect each external PIR 206 to the GIS.

[0063] The description to be presented now is an embodiment of an improved electrical system.

[0064] Figure 3This is a schematic diagram illustrating an embodiment of electrical system 300. In this embodiment, electrical system 300 is an MTSS, particularly an HVDC MTSS, or is intended for use therein. The MTSS can be a modular design, wherein, for example, a new HVDC scheme can be connected via a new bay without major modifications to the original station.

[0065] In this example, the electrical system 300 includes a first bus 302a, a second bus 302b, and a plurality of power transmission media 304 (e.g., feeders for HVDC converters or HVDC cables).

[0066] The electrical system 300 also includes a resistor module 306, which includes one or more resistors, which in this embodiment are PIR resistors. The resistor module 306 is electrically coupled between a first bus 302a and a second bus 302b.

[0067] The electrical system 300 also includes a first switching element 307, such as a first switch. The first switching element 307 is electrically coupled between a first busbar 302a and a second busbar 302b. The first switching element 307 is electrically connected in series with a resistor module 306 between the first busbar 302a and the second busbar 302b.

[0068] For each power transmission medium 304, a corresponding second switching element 308 (e.g., a second switch) is electrically coupled in series between that power transmission medium 304 and the first bus 302a. The corresponding second switching element 308 is arranged to switchably connect that power transmission medium 304 to or disconnect it from the first bus 302a.

[0069] For each power transmission medium 304, a corresponding third switching element 310 (e.g., a third switch) is electrically coupled in series between that power transmission medium 304 and the second bus 302b. The corresponding third switching element 310 is arranged to switchably connect the power transmission medium 304 to or disconnect it from the second bus 302b.

[0070] In some embodiments, resistor module 306 includes only a single resistor, i.e., a single PIR. However, in other embodiments, resistor module 306 includes multiple resistors (i.e., multiple PIRs) and multiple resistor module switches electrically coupled to the multiple resistors. The multiple resistors may be selectively connected in series or in parallel via the multiple resistor module switches. By controlling the resistor module switches, the configuration and total resistance of resistor module 306 can be changed. This advantageously tends to allow feeders with different charging / discharging requirements (e.g., cables of significantly different lengths) to be charged / discharged. Furthermore, this tends to allow multiple feeders to charge / discharge simultaneously.

[0071] In some embodiments, the resistor module may include: a plurality of resistors; a plurality of switches, each switch electrically coupled to one or more of the resistors; and control circuitry operatively coupled to the switches. The plurality of resistors may be selectively connected in a series or parallel configuration via the plurality of switches. The control circuitry is configured to dynamically switch one or more resistors into or out of the series or parallel configuration based on operational requirements, thereby allowing adjustment of the total resistance of the resistor module. The control circuitry enables the selective engagement of individual resistors to provide a desired total resistance according to varying load conditions.

[0072] The resistor module 306 includes a first terminal 312 electrically coupled to a first bus 302a and a second terminal 314 electrically coupled to a second bus 302b.

[0073] In this embodiment, the electrical system 300 also includes a fourth switching element 316 (e.g., a fourth switch) electrically coupled to the first terminal 312 of the resistor module 306. The fourth switching element 316 is a grounding switch connected between the first terminal 312 and ground.

[0074] In this embodiment, the electrical system 300 also includes a fifth switching element 318 (e.g., a fifth switch) electrically coupled to the second terminal 314 of the resistor module 306. The fifth switching element 318 is a grounding switch connected between the second terminal 314 and ground.

[0075] In this embodiment, each power transmission medium 304 includes a corresponding terminal electrically coupled to the first bus 302a. The electrical system 300 also includes a plurality of sixth switching elements 320 (i.e., sixth switches). For each power transmission medium 304, the terminal of that power transmission medium is configured to be selectively connected to ground via a corresponding sixth switching element 320. The sixth switching element 320 is a grounding switch, each connected between the corresponding power transmission medium 304 and ground.

[0076] In this embodiment, the first busbar 302a includes a first busbar terminal 322. The electrical system also includes a seventh switching element 324 (e.g., a seventh switch) electrically coupled to the first busbar terminal 322. The seventh switching element 324 is a grounding switch connected between the first busbar terminal 322 and ground.

[0077] In this embodiment, the electrical system 300 is implemented in a GIS application. Specifically, the electrical system 300 includes a housing or enclosure 326 in which a pressurized gas (typically sulfur hexafluoride (SF6)) is used as the insulating medium. This tends to allow the HVDC system to manage high voltage within a confined space, which is particularly important in urban environments or offshore platforms.

[0078] In this embodiment, the resistor module 306 is located outside the housing 326, i.e., outside the GIS. This is to facilitate the dissipation of heat generated during charging or discharging via the resistor module 306, which might be difficult or impossible if the resistor module 306 were located inside the housing 326. The electrical connection connecting the resistor module 306 to the circuitry of the electrical system 300 passes through the wall of the housing 326 via a pair of sleeves 328. In other words, the resistor module 306 is connected to the GIS using two sleeves 328. The sleeves 328 can form a hermetically tight seal around the electrical connection passing through the wall of the housing 326, thereby preventing or resisting gas leakage from the GIS.

[0079] In this embodiment, each power transmission medium 304 extends through the wall of the housing 326 via a corresponding additional bushing 330. The additional bushing 330 forms an hermetically tight seal around the power transmission medium 304 extending through the wall of the housing 326, thereby preventing or resisting gas leakage from the GIS.

[0080] Therefore, an embodiment of electrical system 300 is provided.

[0081] In the so-called "normal mode" operation of the electrical system 300, when power is supplied to the power transmission medium 304 via the electrical system 300, each power transmission medium 304 is connected to the first bus 302a and disconnected from the second bus 302b. Specifically, for a given power transmission medium 304, the second switching element 308 connecting that power transmission medium 304 to the first bus 302a is closed, while the third switching element 310 connecting that power transmission medium 304 to the second bus 302b is open. Furthermore, by opening the first switching element 307, the second bus 302b is disconnected from the first bus 302a. Additionally, in this embodiment, when not in use, the resistor module 306 is grounded by closing either or both of the fourth switching element 316 and the fifth switching element 318. The sixth switching element 320 is also open. The seventh switching element 324 is also open.

[0082] From this "normal mode", one or more of the power transmission media 304 can discharge.

[0083] Figure 4 A first table 400 is shown, which illustrates certain sequential process steps of an embodiment of the process of discharging the power transmission medium 304.

[0084] At step 402, the power transmission medium 304 operates in "normal mode," wherein the second switching element 308 is closed, and the third switching element 310 is open. The first switching element 307 is open. The fourth switching element 316 and the fifth switching element 318 are closed.

[0085] At step 404, the HVDC converter attached to the power transmission medium 304 is de-energized.

[0086] At step 406, the second switching element 308 is turned on. This electrically isolates the power transmission medium 304 from the first bus 302a.

[0087] At step 408, the fifth switching element 318 is turned on. This removes the ground connection of the fifth switching element 318 via the second bus 302b.

[0088] At step 410, the third switching element 310 is closed. This creates a path for current to flow from the power transmission medium 304 to ground via the third switching element 310, the second bus 302b, the resistor module 306, and the fourth switching element 316.

[0089] The power transmission medium 304 is therefore discharged to ground via the resistor module 306. The resistor module 306 limits or restricts the flow of discharge current from the power transmission medium 304.

[0090] Optionally, at step 412, the sixth switching element 320 is closed. The power transmission medium 304 of the discharge is thus connected to ground via the sixth switching element 320.

[0091] Optionally, at step 414, the third switching element 310 is turned on. Resistor module 306 is thus electrically isolated from the power transmission medium 304. Step 414 tends to allow other intervals to utilize resistor module 306 and the second bus 302b, for example, without affecting or being affected by the interval currently discharging / under maintenance.

[0092] Optionally, at step 416, the fifth switching element 318 is closed. Resistor module 306 is thus grounded. Step 416 tends to enable or facilitate maintenance of resistor module 306 (e.g., PIR maintenance).

[0093] Therefore, an embodiment of the process for discharging the power transmission medium 304 is provided. In this embodiment, to discharge the power transmission medium 304, before discharging it to ground via the resistor module 306 and the fourth switch module 316 by closing the third switch module 310, the power transmission medium 304 is isolated from the first bus 302a by opening the second switch element 308. The third switch module 310 has current-generating capability for this process. Because the resistor module 306 is disconnected from the first bus 302a via the first switch element 307, this operation does not affect other power transmission media 304 connected to the hub.

[0094] The state of discharge from the given power transmission medium 304, for example from Figure 4The state of the electrical system 300 at step 416 of the process, that power transmission medium 304 can then be charged.

[0095] Figure 5 A second table 500 is shown, which illustrates certain sequential process steps of an embodiment of the process of charging the power transmission medium 304.

[0096] At step 502, the power transmission medium 304 is in a discharged state and isolated from the first and second buses 302a and 302b. Specifically, the second switching element 308 and the third switching element 310 are both open. The first switching element 307 is open. The seventh switching element 324 is open. The fourth switching element 316 and the fifth switching element 318 are closed. The sixth switching element 320 is closed.

[0097] At step 504, the sixth switching element 320 is turned on. Therefore, the ground connection of the power transmission medium 304 via the sixth switching element 320 is removed.

[0098] At step 506, the fifth switching element 318 is turned on. Therefore, the ground connection of the second bus 302b via the fifth switching element 318 is removed.

[0099] At step 508, the fourth switching element 316 is turned on. Therefore, the ground connection of resistor module 306 is removed.

[0100] At step 510, the first switching element 307 is closed. Therefore, an electrical connection is established between the first busbar 302a and the second busbar 302b via the resistor module 306.

[0101] At step 512, the third switching element 310 is closed. Therefore, the power transmission medium 304 is electrically connected to the second bus 302b. Consequently, the power transmission medium 304 is charged via the resistor module 306 and the secondary bus 302b. The resistor module 306 limits or constrains the charging current flow to the power transmission medium 304.

[0102] Optionally, once the power transmission medium 304 is charged (e.g., fully charged, or charged to a threshold level), at step 514, the second switching element 308 closes. This directly connects the power transmission medium 304 to the primary bus 302a.

[0103] Optionally, at step 516, the third switching element 310 is turned on. This disconnects the power transmission medium 304 from the second bus 302b and the resistor module 306.

[0104] Optionally, at step 518, the first switching element 307 is turned on. This disconnects the first bus 302a from the second bus 302b and the resistor module 306.

[0105] Optionally, at step 520, the fourth switching element 316 is closed. This connects the resistor module 306 to ground via the fourth switching element 316. The resistor module 306 is thus grounded.

[0106] Optionally, at step 522, the fifth switching element 318 is closed. This connects the second bus 302b to ground via the fifth switching element 318. The second bus 302b is thus grounded. Advantageously, the second terminal 314 is grounded, meaning that both terminals 312 and 314 of the resistor module 306 are grounded for safe maintenance of the resistor module 306.

[0107] Advantageously, some or all of steps 514-522 tend to return the switch station to "normal mode". This allows for maintenance of resistor module 306. It also frees up resistor module 306 for use by other feeders, etc.

[0108] Therefore, an embodiment of the process for charging the power transmission medium 304 is provided. In this embodiment, the power transmission medium 304 is charged by connecting the first bus 302a to the second bus 302b via resistor module 306 by closing the first switching element 307. By keeping the second switching element 308 open, the direct connection between the power transmission medium 304 and the first bus 302a is broken. All switches can remain open, and the third switching element 310 can be closed to connect the power transmission medium 304 to the second bus 302b, allowing the first bus 302a to be charged via resistor module 306.

[0109] In "normal mode", the first busbar 302a can be electrically isolated from the rest of the electrical system 300.

[0110] Figure 6 A third table 600 is shown, which illustrates certain sequential process steps of an embodiment of the process of isolating the first busbar 302a.

[0111] At step 602, the power transmission medium 304 operates in "normal mode," wherein the second switching element 308 is closed, and the third switching element 310 is open. The first switching element 307 is open. The fourth switching element 316 and the fifth switching element 318 are closed.

[0112] At step 604, the second switching element 308 is turned on. This electrically isolates the power transmission medium 304 from the first bus 302a.

[0113] The first bus 302a is therefore electrically isolated from the power transmission medium 304 and the second bus 302b.

[0114] All bays / feeders are isolated from the first busbar 302a in this manner (i.e., by opening their respective second switching elements 308). Alternatively, one or more bays / feeders may be at least discharged / grounded.

[0115] At step 606, the seventh switching element 324 is closed. Therefore, the first busbar 302a is connected to ground via the seventh switching element 324.

[0116] One or more of the power transmission media 304 can still operate independently and can also discharge via the second bus 302b, resistor module 306 and fourth switching element 316, while the first bus 302a remains isolated and grounded.

[0117] Therefore, an embodiment of the process of isolating the first busbar 302a is provided.

[0118] In "normal mode", the power transmission medium 304 can be electrically isolated from the rest of the electrical system 300.

[0119] Figure 7 A fourth table 700 is shown, which illustrates certain sequential process steps of an embodiment of the process of isolating the power transmission medium 304 from the GIS.

[0120] At step 702, the power transmission medium 304 operates in "normal mode," wherein the second switching element 308 is closed, and the third switching element 310 is open. The first switching element 307 is open. The fourth switching element 316 and the fifth switching element 318 are closed.

[0121] At step 704, the second switching element 308 is turned on. This electrically isolates the power transmission medium 304 from the first bus 302a. The power transmission medium 304 is thus isolated from the first and second buses 302a and 302b.

[0122] Therefore, an embodiment of the process for isolating the power transmission medium 304 is provided.

[0123] Compared to conventional systems 100 and 200, the aforementioned electrical system 300 advantageously tends to offer reduced complexity and a reduced number of components for each feeder / power transmission medium at the station. Specifically, the electrical system can individually charge or discharge any feeder in the feeder 304 using a single common resistor module 306 (i.e., one or more PIRs). This is preferably achieved by using a second busbar 302b, which is connected to the first busbar via resistor module 306, switching element 307, and grounding circuits 316 and 318.

[0124] Advantageously, by placing resistor module 306, first switching element 307, fourth switching element 316, and fifth switching element 318 between the first and second buses 302a, 302b, and sharing it as a common circuit among all power transmission media 304, the need for these components (i.e., resistor module 306, first switching element 307, fourth switching element 316, and fifth switching element 318) tends to be eliminated for each interval, i.e., for each individual power transmission medium. This tends to reduce the overall component count.

[0125] Furthermore, at the cost of including these four components in the hub circuitry, each subsequent power delivery medium added to the system tends to use two fewer grounding switches, one fewer current-generating isolation switch, and no additional PIR.

[0126] In addition, the number of casings in GIS tends to decrease.

[0127] Advantageously, in the aforementioned electrical system 300, opening the first switching element 307 tends to allow any of the DC hubs or power transmission media 304 to be isolated for maintenance, while the other remains operational.

[0128] To maintain the power transmission medium 304, the sixth switching element 320 can be closed, while the second switching element 308 can be opened, and the other power transmission media 304 and the hub continue to operate. (The third switching element 310 will also be opened.) For maintenance of the hub itself, the seventh switching element 324 can be used to ground the first bus 302a while allowing any continued operation of the power transmission medium 304. For this purpose, all second switching elements 308 can be turned on.

[0129] Advantageously, resistor module 306 (i.e., one or more PIRs) can be isolated from power transmission medium 304 and hub, and grounded via fourth and fifth switching elements 316, 318 for maintenance, while the rest of the switch station continues to operate. If needed, for example for increased safety, a second disconnecting switch can be placed on the right-hand side of resistor module 306, i.e., between second terminal 314 and second bus 302b.

[0130] In the above embodiment, the electrical system includes only a single resistor module and grounding circuit. In the above embodiment, this is connected between the first and second busbars. However, in other embodiments, one or more additional or "spare" resistor modules and grounding circuits may be added in parallel with the first resistor module and grounding circuit. Such one or more additional resistor modules and grounding circuits will be connected between the first and second busbars. One or more additional resistor modules and grounding circuits advantageously tend to reduce the risk of energy unavailability during maintenance.

[0131] In other words, in some embodiments, the electrical system may further include: an additional resistor module comprising one or more additional resistors electrically coupled between the first bus and the second bus; and an additional switch electrically coupled between the first bus and the second bus, the additional switch being connected in series with the additional resistor module.

[0132] It will be understood that, in Example 100, various other electrical components may be located at any particular location or have any particular feature / component. These may include switches, transformers, resistors, reactors, surge arresters, harmonic filters, and other components well known in the art.

[0133] It will be understood that cables used as power transmission media can include non-limiting examples of cross-linked polyethylene (XLPE) and / or mass-impregnated (MI) insulated cables. Such cables may include conductors (e.g., copper or aluminum) surrounded by insulation layers. The dimensions of the cable and its associated layers may vary depending on the specific application (and particularly the operating voltage requirements). In applications such as submarine installations, the cable may also include reinforcement or 'armoring'. The cable may also include a sheath / shielding grounded at one or more locations. Power transmission media can refer to busbars or the like without cables (e.g., direct connections to a converter station).

[0134] Throughout this specification, any reference to an example or similar language for a particular method or device implies that a particular feature, structure, or characteristic described in connection with that example is included in at least one implementation of the method and device described herein. The terms “comprising,” “including,” “having,” and variations thereof mean “including, but not limited to…” unless otherwise expressly stated. A list of enumerated items does not imply that any or all of the items are mutually exclusive unless otherwise expressly stated. Unless otherwise expressly stated, the terms “a,” “an,” and “the” also mean “one or more”.

[0135] As used herein, a list containing the conjunction “and / or” includes any single item in the list or a combination of items in the list. For example, a list of A, B, and / or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term “one or more of…” includes any single item in the list or a combination of items in the list. For example, one or more of A, B, and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term “one of…” includes one and only one of any single item in the list. For example, “one of A, B, and C” includes only A, only B, or only C, and excludes combinations of A, B, and C. As used herein, “selected as a member of the group consisting of A, B, and C” includes one and only one of A, B, or C, and excludes combinations of A, B, and C. As used in this article, “selecting members of a group consisting of A, B, and C and their combinations” includes only A, only B, only C, combinations of A and B, combinations of B and C, combinations of A and C, or combinations of A, B, and C.

[0136] Aspects of the disclosed methods and apparatuses are described with reference to schematic flowcharts and / or block diagrams of methods, apparatus, systems, and program products. It will be appreciated that each block of the schematic flowcharts and / or block diagrams, and combinations of blocks in the schematic flowcharts and / or block diagrams, can be implemented by code. This code can be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus to produce a machine, such that instructions executable via the processor of the computer or other programmable data processing apparatus create components for implementing the functions / actions specified in the schematic flowcharts and / or block diagrams.

[0137] The schematic flowcharts and / or block diagrams and / or tables in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, systems, methods, and program products. In this respect, each box in the schematic flowcharts and / or block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing one or more specified logical functions.

[0138] It will be understood that the numerical values ​​described herein are intended only to help illustrate the work of the invention and may vary depending on the requirements of a given power transmission network, its components, or power transmission application.

[0139] Listing or discussing clearly prior disclosed documents or information in this specification should not be construed as an admission that such documents or information are part of the prior art or common general knowledge.

[0140] Unless the context otherwise requires, preferences and options for a given aspect, feature, or parameter of the invention should be considered as having been disclosed in combination with any and all preferences and options for all other aspects, features, and parameters of the invention.

Claims

1. An electrical system comprising: First busbar; Second busbar; A resistor module comprising one or more resistors, the resistor module being electrically coupled between a first busbar and a second busbar; A first switching element is electrically coupled between the first bus and the second bus, and the first switching element is connected in series with the resistor module; as well as Multiple power transmission media; in Each of the plurality of power transmission media is electrically coupled to the first bus via a corresponding second switching element; as well as Each of the plurality of power transmission media is electrically coupled to the second bus via a corresponding third switching element.

2. The electrical system according to claim 1, wherein, The resistor module includes: Multiple resistors; and A plurality of switching elements, each of the plurality of switching elements being electrically coupled to one or more resistors in the resistor; in The plurality of resistors may be selectively connected in series or in parallel via the plurality of switching elements.

3. The electrical system according to any of the preceding claims, wherein The resistor module includes: Electrically coupled to the first terminal of the first busbar; and Electrically coupled to the second terminal of the second busbar; The electrical system further includes a fourth switching element electrically coupled to the first terminal; and The first terminal is configured to be selectively connected to ground via the fourth switching element.

4. The electrical system according to any of the preceding claims, wherein The resistor module includes: Electrically coupled to the first terminal of the first busbar; and Electrically coupled to the second terminal of the second busbar; The electrical system further includes a fifth switching element electrically coupled to the second terminal; and The second terminal is configured to be selectively connected to ground via the fifth switching element.

5. The electrical system according to any of the preceding claims, wherein Each of the plurality of power transmission media includes a corresponding terminal electrically coupled to the first bus; The electrical system also includes multiple sixth switching elements; and For each of the plurality of power transmission media, the terminal of that power transmission media is configured to be selectively connected to ground via a corresponding sixth switching element.

6. The electrical system according to any of the preceding claims, wherein The first busbar includes first busbar terminals; The electrical system also includes a seventh switching element electrically coupled to the first bus terminal; and The first bus terminal is configured to be selectively connected to ground via the seventh switching element.

7. The electrical system according to any of the preceding claims, further comprising: An additional resistor module comprising one or more additional resistors, the additional resistor module being electrically coupled between the first bus and the second bus; and An additional switching element, electrically coupled between the first bus and a separate second bus, is connected in series with the additional resistor module.

8. The electrical system according to any of the preceding claims, further comprising: The outer shell; in which The first busbar, the second busbar, each first switching element, and each second switching element are encapsulated in the housing; and The resistor module is located outside the housing.

9. The electrical system according to claim 8, wherein, The housing contains the gas-insulated switchgear (GIS) system.

10. The electrical system according to any of the preceding claims, wherein, The electrical system is a multi-terminal switch station (MTSS).

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