Supporting multi-circuit inter-backup gas insulated transmission line system

Abstract

The application relates to the field of high-voltage power transmission lines, and discloses a gas insulated transmission line system supporting multiple loop inter-backup. A single-phase common bus is arranged at the station end outgoing line side. For the phase conductor of each loop in the multiple loop GIL, a first switch for connecting the phase conductor to the station equipment and a second switch for connecting the phase conductor to the single-phase common bus are arranged respectively. When the N-1 working condition has been reached, if the second loop phase conductor fails and at least one healthy phase conductor of the second loop still exists, the healthy phase conductor of the second loop is connected to replace the failed phase conductor of the first loop to participate in the formation of a three-dimensional transmission circuit by operating the corresponding switch, thereby realizing backup. Without increasing the number of phase devices along the full length of the GIL line, the single-phase common bus and the switch switching structure are arranged at the station end, cross-loop phase recombination and inter-backup between multiple loops are realized, and the reliability under the N-2 fault is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to high-voltage power transmission lines, in particular to a gas insulated transmission line wiring system supporting multiple circuits as backup for each other. BACKGROUND

[0002] This section is intended to provide background information to facilitate a better understanding of the embodiments of the present application set forth in the claims. The content of this section is not to be taken as an acknowledgement that it is prior art merely by virtue of its inclusion in this section.

[0003] A gas insulated transmission line (GIL) is often used in high-voltage and extra-high-voltage power transmission projects due to its compact structure and high transmission capacity. Once a GIL line fails, it is usually a permanent failure, and the normal operation can be restored only by removing and replacing the failed section. Since the GIL is usually laid in a narrow space such as a tunnel, the maintenance conditions are limited, and the fault handling period is usually 10-15 days, so the fault recovery time is relatively long.

[0004] To improve the reliability of system operation, a backup phase can be provided in the GIL line, so that when a fault occurs in a certain phase, the fault phase can be switched to the backup phase to shorten the power outage time. However, laying a backup phase along the entire length of the GIL line will significantly increase the size of the GIL tunnel and the number of equipment, resulting in a substantial increase in project investment and poor economic efficiency.

[0005] For projects with a long tunnel length, if a backup phase is used along the entire line, more GIL conductors and larger tunnel transportation and installation spaces will be required, resulting in further increases in equipment and civil engineering costs, and even poorer economic efficiency. SUMMARY

[0006] The purpose of the present application is to provide a gas insulated transmission line system supporting multiple circuits as backup for each other, which realizes cross-circuit phase reconfiguration and mutual backup between multiple circuits by setting a single-phase common bus and a switch switching structure at the station end without increasing the number of backup phases along the entire length of the GIL line, thereby improving the reliability under N-2 failure.

[0007] The present application discloses a gas insulated transmission line system supporting multiple circuits as backup for each other, comprising a plurality of circuit gas insulated transmission lines arranged between a first station and a second station, each circuit gas insulated transmission line comprising a plurality of phase conductors for transmitting different phase electric energy respectively,

[0008] A single-phase common bus capable of being electrically connected to the corresponding phase conductors of the plurality of circuit gas insulated transmission lines at the same time is arranged at the outgoing side of the first station and the second station;

[0009] The first station and the second station are provided with first switch devices for connecting the phase conductors of each circuit of the multi-circuit gas insulated transmission line to the station equipment and second switch devices for connecting the phase conductors to the single-phase common bus, respectively.

[0010] When the first circuit gas insulated transmission line is in the state of exiting operation, the phase conductor of the second circuit fails and at least one healthy phase conductor of the second circuit still exists, the system is configured to operate the corresponding switch devices to make the healthy phase conductor of the second circuit replace the failed phase conductor of the first circuit to participate in the formation of the three-dimensional transmission circuit through the single-phase common bus, thereby realizing the cross-circuit backup between the multi-circuit gas insulated transmission lines in the N-2 state.

[0011] In a preferred embodiment, for each phase, all the phase conductors of the same phase in the multi-circuit gas insulated transmission line are only connected to the single-phase common bus corresponding to the phase through the respective second switch devices, so that when any circuit of the same phase fails, the other circuits can realize backup through the corresponding single-phase common bus.

[0012] In a preferred embodiment, the operation of the corresponding switch devices includes:

[0013] When the phase conductor of the gas insulated transmission line of the second circuit is detected to fail, the first switch device and the second switch device corresponding to the failed phase conductor of the circuit are controlled to be opened to make the failed phase conductor exit operation;

[0014] An other healthy phase conductor in the second circuit is selected, the second switch device between the healthy phase conductor and the single-phase common bus is closed to connect the healthy phase conductor to the station equipment through the single-phase common bus, and the corresponding first switch device is closed to make the healthy phase conductor replace the failed phase conductor of the first circuit to perform the power transmission function in the three-dimensional transmission circuit, and meanwhile, the first switch device and the second switch device corresponding to the remaining phase conductors of the second circuit which do not replace are opened.

[0015] In a preferred embodiment, the single-phase common bus is provided with three phases in the first station and / or the second station, respectively, to realize the backup between the multi-circuits when any phase of the three phases fails.

[0016] In a preferred embodiment, the first switch device and the second switch device are switch components with isolation function, and an electrical and / or logical interlock is arranged between the first switch device and the second switch device corresponding to the same phase conductor to prevent unexpected closing of the two.

[0017] In a preferred embodiment, the disconnectors and grounding switches for switching the phase conductors as backup of each other are respectively provided with independent measuring and control devices, the measuring and control devices exchange information with the measuring and control devices in the outgoing line bay through a communication network, collect actual position states of the switch devices and the grounding switches, and cooperatively control the electrical and / or logical interlocks between the first switch device and the second switch device based on the position states.

[0018] In a preferred embodiment, two sets of short line protection devices are provided at each outgoing line of the first station and the second station,

[0019] The short line protection devices are respectively used for protecting the short line section that is still in an electrified state when the loop operation is formed by the switch in the station after the line outgoing line is isolated.

[0020] In a preferred embodiment, the first station and / or the second station is a substation with GIS arrangement, and in the substation:

[0021] Two groups of the switch devices are provided in the GIS bay for each outgoing line, wherein the switch devices are used for connecting the phase conductors of the outgoing line to the GIS bus, and the other group of the switch devices are used for connecting the phase conductors of the outgoing line to the single-phase common bus of the corresponding phase;

[0022] The single-phase common bus is arranged in a vertical column relative to the GIS bus, the switch devices for connecting to the single-phase common bus are vertically arranged on both sides of the GIS bay,

[0023] And the outgoing line circuit breaker and the switch devices cooperating with the outgoing line circuit breaker are devices for separate-phase operation, so as to complete the arrangement of the single-phase common bus and the corresponding switch devices without increasing the size of the GIS room.

[0024] In a preferred embodiment, the second station and / or the first station is a lead-in station, and in the lead-in station:

[0025] The single-phase common bus for realizing the backup connection of the phase conductors adopts an open soft bus arrangement, the open soft bus is in a non-electrified state in a normal operation state, and the voltage transformer and the current transformer corresponding to the open soft bus adopt an open arrangement.

[0026] In one preferred embodiment, busbars are provided to electrically connect the outer shells of the phase conductors along the multi-circuit gas insulated transmission line, the busbars are arranged in series and electrically connected between the multiple circuits and multiple phases, forming an overall connected three-phase busbar system, and the current carrying capacity is checked according to the maximum operating current in single-circuit operation, to adapt to the operating conditions when the power transmission circuit is reorganized through different circuit phase conductors.

[0027] In the embodiments of the present application, by providing a single-phase utility bus at the station end outgoing line side, and configuring each phase conductor of each circuit with a first switching device connected to the station equipment and a second switching device connected to the single-phase utility bus, the system can re-enter one of the healthy phase conductors in the second circuit into the power transmission path of the first circuit through the single-phase utility bus when a fault occurs in a phase conductor of the second circuit under N-1 conditions, thereby completing phase reorganization across circuits, thereby realizing mutual fault backup channels between multi-circuit GIL lines without increasing equipment phase conductors along the entire GIL line, and improving the overall operation reliability and fault recovery capability of the system under N-2 conditions.

[0028] Each of the technical features disclosed in the above summary, each of the technical features disclosed in the following embodiments and examples, and each of the technical features disclosed in the drawings can be freely combined with each other to form various new technical solutions (which should all be considered to have been described in the present specification), unless such combination of technical features is technically infeasible. For example, features A+B+C are disclosed in one example, features A+B+D+E are disclosed in another example, features C and D are equivalent technical means that play the same role and can only be used alternatively, and feature E can be combined with feature C technically, then the scheme of A+B+C+D should not be considered to have been described because it is technically infeasible, and the scheme of A+B+C+E should be considered to have been described. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the electrical wiring of a substation according to an embodiment of the present application;

[0030] Figure 2 is a schematic diagram of the status of the outgoing line disconnector of a substation at the time of a fault according to an embodiment of the present application;

[0031] Figure 3 is a schematic diagram of the GIS arrangement of a substation according to an embodiment of the present application;

[0032] Figure 4 is a schematic diagram of the end face of the GIS arrangement of a substation according to an embodiment of the present application;

[0033] Figure 5 is a schematic diagram of the connection of the terminal station according to an embodiment of the present application;

[0034] Figure 6 is a schematic diagram of the connection of the terminal station according to an embodiment of the present application;

[0035] Figure 7 is a schematic diagram of the connection of the terminal station according to an embodiment of the present application;

[0036] Figure 8 is a schematic diagram of the connection of the terminal station according to an embodiment of the present application. DETAILED DESCRIPTION

[0037] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present application.

[0038] Explanation of some concepts:

[0039] GIL: Gas-insulated Metal-enclosed Transmission Line, is a high-voltage, large-current electrical equipment with coaxial arrangement of gas insulation, shell and conductor. It is generally composed of aluminum alloy shell, aluminum alloy conductor, insulating gas and epoxy support.

[0040] Standby phase: refers to the additional phase or phases of equipment in a multi-phase power supply system to enhance the reliability and fault tolerance of the system.

[0041] N-1 criterion: N represents the number of all elements (such as generator sets, transmission lines, transformers, circuit breakers, etc.) in operation in the power grid. N-1 refers to the new operating state of the power grid after any one key element (such as a line or a transformer) fails and is disconnected in the operating state. The N-1 criterion means that after any element (such as a line, a transformer, a generator, etc.) in the power system is disconnected due to failure in the normal operating mode, the system must be able to maintain stable operation and not cause any other element to be overloaded, the system voltage and frequency to exceed the allowed range, while ensuring that the normal power supply of users is not affected.

[0042] Terminal station: a place where overhead lines are converted to GIL or cables, and the present application specifically refers to a place where overhead lines are converted to GIL.

[0043] The following is a brief description of some of the innovations of the embodiments of the present application:

[0044] 1. By setting single-phase utility bus and two groups of switching devices according to phase, the same phase replacement can be realized when a phase fault occurs in the second loop under the N-1 condition, and a shared spare resource pool is constructed.

[0045] 2. The spare structure is arranged at the outlet side of the substation / lead station for the first time, without increasing the phase conductor along the full length of the GIL line, which significantly reduces the equipment quantity and the size of the tunnel civil engineering.

[0046] 3. The state of the switch and the knife switch is collected by the independent measurement and control device, and the controllability of fault detection and switching operation and the anti-misoperation ability are realized by cooperating with the electrical and logical locking mechanism.

[0047] 4. In the GIS substation, the single-phase utility bus is vertically and compactly arranged to realize the integration without expansion; in the lead station, the open soft bus is used as the single-phase utility bus to improve the economy and the arrangement flexibility.

[0048] 5. The three-phase bus along the line is set in parallel with the multi-loop to maintain the shell potential balance and meet the cross-loop operating current demand, and to ensure the electrical safety under the standby operation mode.

[0049] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0050] The present application relates to a kind of gas insulated transmission line system supporting multi-loop mutual standby, comprising: multiple loop gas insulated transmission line is arranged between first station and second station, and each loop gas insulated transmission line includes multiple phase conductors for respectively transmitting different phase electric energy.

[0051] Single-phase utility bus capable of being simultaneously electrically connected with the corresponding phase conductor of multiple loop gas insulated transmission line is arranged at the outlet side of first station and second station.

[0052] In first station and second station, for the phase conductor of each loop in multiple loop gas insulated transmission line, first switching device for connecting the phase conductor into station equipment and second switching device for connecting the phase conductor into single-phase utility bus are arranged respectively.

[0053] The system is configured to: when the first loop gas insulated transmission line has been in the condition of exiting operating state, the phase conductor of the second loop fails and at least one healthy phase conductor of the second loop still exists, by operating corresponding switching device, the healthy phase conductor of the second loop replaces the fault phase conductor of the first loop to participate in the formation of three-dimensional power transmission circuit through single-phase utility bus, so as to realize the cross-loop mutual standby between multiple loop gas insulated transmission line under N-2 condition.

[0054] Briefly describe the mechanism of the application, in this application, by setting single-phase public bus according to phase at the station end, and respectively configuring selectively accessible switching devices between each phase conductor of each return line and the single-phase public bus in the station, so that multiple loops have the ability to be electrically connected to the same single-phase public bus at any time. Therefore, when the system has been in N-1 working condition, and a permanent fault occurs in a phase conductor of a second loop, the system can quickly disconnect the corresponding switching device of the loop after detecting the fault, and select another healthy phase conductor of the second loop to close to the single-phase public bus, complete the phase recombination of the first loop and the second loop, and then re-connect the station equipment through the single-phase public bus, so as to complete the cross-loop replacement of the fault phase conductor without changing the overall topology of the line, thereby improving the reliability under N-2 fault.

[0055] In the above manner, the corresponding phase conductor of each loop no longer only undertakes the three-phase power transmission task of the loop it belongs to, but under the convergence of the single-phase public bus, it forms a shared standby resource at the phase level. After the fault of the second loop occurs, the system can replace the fault phase conductor of the first loop with the other healthy phase conductor of the second loop, without the need to increase the phase along the full length of the GIL line, or to add new line channels or change the tunnel section, so as to realize the quick mutual standby between multiple loops under N-2 working condition. Thus, on the one hand, the engineering investment of the tunnel and the GIL body can be significantly reduced, and on the other hand, the recovery time of the fault loop can be greatly shortened, and the operating resilience and reliability of the system under N-2 fault condition can be improved (N-2 refers to the operating state after another key element (such as a line or a transformer) fails and is disconnected based on the original N-1 state of the power grid).

[0056] It should be noted that the embodiments described below in the application are based on the premise that the power grid is already in N-1 working condition, i.e. one loop (first loop) of the gas insulated transmission line has been out of operation due to fault or maintenance; on this basis, when a phase conductor of another loop (second loop) also fails, the cross-loop phase recombination is realized through the single-phase public bus and switching described in the application.

[0057] In some optional embodiments, for each phase, all phase conductors of the same phase in the multiple-loop gas insulated transmission line are only electrically connected to the single-phase public bus corresponding to the phase through the respective second switching devices, so that when a fault occurs in any loop of the same phase, the other loops can realize mutual standby through the corresponding single-phase public bus.

[0058] Specifically, the operation of the respective switch devices in some optional embodiments can be operated in the following way: when a phase conductor of the second circuit gas insulated transmission line is detected to be faulty, the first switch device and the second switch device corresponding to the circuit phase conductor are controlled to be opened, so that the faulty phase conductor is taken out of operation. An other healthy phase conductor in the second circuit is selected, the second switch device between the healthy phase conductor and the single-phase common bus is closed, so that the healthy phase conductor is electrically connected to the station equipment through the single-phase common bus, and the corresponding first switch device is closed, so that the healthy phase conductor replaces the faulty phase conductor in the first circuit in the three-dimensional power transmission circuit, and at the same time, the first switch device and the second switch device corresponding to the remaining phase conductors in the second circuit which are not replaced are opened.

[0059] That is, the phase conductors of each circuit in the present application are no longer used only for three-phase power transmission of the circuit, but jointly constitute a shared spare resource pool. In the working condition that the first circuit has been taken out of operation due to failure or maintenance, when a phase conductor of the second circuit fails, the system can adjust the connection in the minimum range, only the related switch devices of the faulty phase of the second circuit and the selected healthy phase of the second circuit are opened and closed, so that the cross-circuit replacement of the faulty phase of the first circuit is completed, and the phase recombination is completed, without the need to change the connection of other normal phases or normal circuits.

[0060] In specific applications, the above switch operation can be automatically completed by the station protection and measurement and control device, or can be performed by the operation personnel under the assistance of the monitoring system. For example, in some optional embodiments, the disconnecting switch and the grounding knife switch for performing the spare switching of the phase conductors are respectively provided with independent measurement and control devices, the measurement and control devices interact with the measurement and control devices in the outgoing interval through a communication network, collect the actual position state of the switch devices and the grounding knife switch, and cooperatively control the electrical and / or logical interlocking between the corresponding first switch device and the second switch device based on the position state, so as to prevent unintended closing of the two.

[0061] Among them, "unintended closing" refers to:

[0062] 1. The corresponding first switch device and the second switch device of the phase conductor which has been judged to be faulty are in the closed state at the same time.

[0063] 2. The corresponding first switch device and the second switch device of the healthy phase conductor in the second circuit which does not participate in the spare connection recombination are in the closed state at the same time.

[0064] 3. For the healthy phase conductor in the first circuit which has been taken out of operation, the second switch device connected to the single-phase common bus is in the closed state, and such a healthy phase conductor is only allowed to be electrically connected to the station equipment through the first switch device, and should not be connected to the single-phase common bus through the second switch device.

[0065] The wiring principle of the application is described below in conjunction with the drawings, and it should be understood that the description is only to enable those skilled in the art to better implement after reading the application, and is not a limitation of the application. Various equivalent replacements, improvements or modifications made by those skilled in the art without departing from the spirit and essence of the application shall be considered to fall within the scope of the application.

[0066] As Figure 1 shown is a 500kV multi-circuit GIL outgoing line wiring schematic diagram of the first station side in an embodiment of the application. This embodiment takes two sections of main bus 500kV1M, 500kV2M and seven-circuit GIL outgoing line as an example to describe the station wiring structure of the application. The black part in the figure represents the conventional wiring, and the blue part represents the single-phase common bus and its connection switch device related to the backup scheme of the application.

[0067] Outgoing line 1~outgoing line 3 are arranged in the upper part of the figure, and outgoing line 4~outgoing line 7 are arranged in the lower part of the figure. Each outgoing line includes A, B, C three-phase phase conductors and their corresponding outgoing line circuit breakers and disconnectors. For the A phase of each outgoing line, two groups of switch devices for selective access are configured at the outgoing line side, one group of switch devices is connected to the 500kV1M or 500kV2M main bus through the outgoing line circuit breaker to form the conventional running channel of the circuit; the other group of switch devices connects the A phase conductor of the outgoing line to the 500kV single-phase A common bus shown in the figure, which is used to realize mutual backup with the A phase conductors of other circuits when a fault occurs. In normal operation, the single-phase common bus is in a non-live state, the disconnectors between each outgoing line and the single-phase common bus are in a disconnected state, the phase outgoing line disconnectors are closed, and the lines are connected to the main bus through the outgoing line interval and operated in a conventional manner.

[0068] As Figure 2 shown is a 500kV multi-circuit GIL outgoing line wiring schematic diagram of the first station side in an embodiment of the application. This embodiment takes two sections of main bus 500kV1M, 500kV2M and seven-circuit GIL outgoing line as an example to describe the station wiring structure of the application. The black part in the figure represents the conventional wiring, and the blue part represents the single-phase common bus and its connection switch device related to the backup scheme of the application. Figure 1

[0069] When a GIL of a certain phase of outgoing line 4 fails, the whole outgoing line 4 is taken out of operation in this embodiment for maintenance of the circuit, at this time, the outgoing line disconnectors of outgoing line 4 are disconnected, the disconnectors connected to the single-phase common bus remain disconnected, and the remaining circuits remain in normal operation.

[0070] On the basis of the outgoing line 4 being taken out of operation, when the GIL of the same phase of outgoing line 5 also fails, Figure 2 ​A state of reconnection of outgoing line 4 and outgoing line 5 through single-phase common bus is shown. For example, in the case of failure of C phase of both outgoing lines, the A phase and B phase outgoing line disconnectors of outgoing line 4 are in the closed state, and the disconnectors connected to the single-phase common bus are in the open state; the C phase outgoing line disconnector of outgoing line 4 is in the open state, and the disconnector connected to the single-phase common bus is in the closed state. The B phase and C phase outgoing line disconnectors of outgoing line 5 and the disconnectors connected to the single-phase common bus are both in the open state, and the A phase outgoing line disconnector of outgoing line 5 and the disconnector connected to the single-phase common bus are in the closed state, so that the A phase of outgoing line 5 is electrically connected to the C phase device in the string of original outgoing line 4 through the single-phase common bus, and the A phase, B phase and C phase of outgoing line 4 form a new three-phase outgoing line. The on-off position relationship of the disconnectors is shown in Figure 2

[0071] In the on-off position of the disconnectors, the A phase and B phase of outgoing line 4 and the A phase of outgoing line 5 are connected to the main bus as new A phase, B phase and C phase of the outgoing line, and the C phase conductors of original outgoing line 4 and outgoing line 5 that have failed are out of operation, and only the devices in the string are reserved as a passage through the single-phase common bus. In this way, in the case of failure of the C phase of outgoing line 4 and outgoing line 5, the three-phase outgoing line can still be connected to the power grid through the connection state shown in Figure 2

[0072] In the above connection mode, when the outgoing line disconnector isolates the outgoing line of the corresponding line from the system, the outgoing line circuit breaker and other switch devices in the station can still form a loop operation mode, so that the short lead section adjacent to the outgoing line circuit breaker is still in a live state. Therefore, in some optional embodiments, two sets of short lead protection devices are arranged at each outgoing line of the first station and the second station, and the short lead protection devices are respectively used for protecting the short lead section that is still in a live state when the loop operation is formed by the switch in the station after the outgoing line of the line is isolated.

[0073] In some optional embodiments, the first station or the second station is a substation adopting GIS arrangement, and the plane arrangement and cross-sectional arrangement of GIS are described below with reference to Figure 3 and Figure 4 respectively. In some optional embodiments, two groups of switch devices are arranged in the GIS compartment for each outgoing line, in which one group of switch devices is used for connecting the phase conductor of the outgoing line to the GIS bus, and the other group of switch devices is used for connecting the phase conductor of the outgoing line to the single-phase common bus of the corresponding phase.

[0074] For example, in the case of failure of the C phase of both outgoing lines, the A phase and B phase outgoing line disconnectors of outgoing line 4 are in the closed state, and the disconnectors connected to the single-phase common bus are in the open state; the C phase outgoing line disconnector of outgoing line 4 is in the open state, and the disconnector connected to the single-phase common bus is in the closed state. The B phase and C phase outgoing line disconnectors of outgoing line 5 and the disconnectors connected to the single-phase common bus are both in the open state, and the A phase outgoing line disconnector of outgoing line 5 and the disconnector connected to the single-phase common bus are in the closed state, so that the A phase of outgoing line 5 is electrically connected to the C phase device in the string of original outgoing line 4 through the single-phase common bus, and the A phase, B phase and C phase of outgoing line 4 form a new three-phase outgoing line. The on-off position relationship of the disconnectors is shown in Figure 3 ​​Fig. 1 shows a plan view of a GIS arrangement of the first station or the second station in an embodiment of the present application. The black part in the figure is a conventional GIS outgoing line interval and busbar interval arrangement, a plurality of GIS intervals are arranged in sequence along the length direction of the GIS room, forming several 500 kV intervals. The single-phase common bus and the switch device connected thereto are marked in blue in the figure. The single-phase common bus is arranged along one side above the GIS interval. A switch device connected to the single-phase common bus is arranged at the position of each outgoing line GIS interval, for realizing the electrical connection between the outgoing line phase conductor and the single-phase common bus. As shown in Fig. 1, the single-phase common bus is arranged along one side above the GIS interval. A switch device connected to the single-phase common bus is arranged at the position of each outgoing line GIS interval, for realizing the electrical connection between the outgoing line phase conductor and the single-phase common bus. Figure 4 Fig. 2 shows a cross-sectional view of the GIS arrangement shown in Fig. 1. The lower part in the figure is a conventional GIS device body; the single-phase common bus and its support structure are shown in blue in the upper part. In some alternative embodiments, the single-phase common bus is arranged in a vertical column above the GIS interval, and is connected to the phase conductor in each outgoing line interval through a vertically arranged switch device (DS, disconnecting switch) or connecting conductor, so that the single-phase common bus and its matching switch device can be added above the GIS interval without changing the horizontal arrangement of the existing GIS device, for implementing the aforementioned multi-loop backup connection scheme. Figure 3 Fig. 3 shows a cross-sectional view of the GIS arrangement shown in Fig. 2. The lower part in the figure is a conventional GIS device body; the single-phase common bus and its support structure are shown in blue in the upper part. In some alternative embodiments, the single-phase common bus is arranged in a vertical column above the GIS interval, and is connected to the phase conductor in each outgoing line interval through a vertically arranged switch device (DS, disconnecting switch) or connecting conductor, so that the single-phase common bus and its matching switch device can be added above the GIS interval without changing the horizontal arrangement of the existing GIS device, for implementing the aforementioned multi-loop backup connection scheme.

[0075] In the above embodiments, the first station and / or the second station are taken as an example of a substation arranged with GIS. However, the station end form described in the present application is not limited to GIS substations. In actual engineering, the first station and / or the second station can also be a lead-in station for transitioning with overhead lines, cables or long-distance GIL tunnels, which has different site conditions and busbar forms from substations. To show that the multi-loop backup scheme of the present application is also applicable to lead-in stations, and to facilitate the implementation of the multi-loop backup scheme of the present application in different types of station ends, the connection structure and the arrangement of the single-phase common bus when the first station or the second station is a lead-in station are described below with reference to Figure 5 and Figure 6 Fig. 4 shows a plan view of a GIS arrangement of the first station or the second station in an embodiment of the present application. The black part in the figure is a conventional GIS outgoing line interval and busbar interval arrangement, a plurality of GIS intervals are arranged in sequence along the length direction of the GIS room, forming several 500 kV intervals. The single-phase common bus and the switch device connected thereto are marked in blue in the figure. The single-phase common bus is arranged along one side above the GIS interval. A switch device connected to the single-phase common bus is arranged at the position of each outgoing line GIS interval, for realizing the electrical connection between the outgoing line phase conductor and the single-phase common bus. As shown in Fig. 4, the single-phase common bus is arranged along one side above the GIS interval. A switch device connected to the single-phase common bus is arranged at the position of each outgoing line GIS interval, for realizing the electrical connection between the outgoing line phase conductor and the single-phase common bus.

[0076] In some alternative embodiments, in the lead-in station, the single-phase common bus for realizing the backup connection of the phase conductors is arranged in an open soft busbar arrangement. The open soft busbar is in a non-live state in the normal operating state, and the voltage transformer and the current transformer corresponding to the open soft busbar are arranged in an open arrangement.

[0077] Fig. 5 shows a cross-sectional view of the GIS arrangement shown in Fig. 4. The lower part in the figure is a conventional GIS device body; the single-phase common bus and its support structure are shown in blue in the upper part. In some alternative embodiments, the single-phase common bus is arranged in a vertical column above the GIS interval, and is connected to the phase conductor in each outgoing line interval through a vertically arranged switch device (DS, disconnecting switch) or connecting conductor, so that the single-phase common bus and its matching switch device can be added above the GIS interval without changing the horizontal arrangement of the existing GIS device, for implementing the aforementioned multi-loop backup connection scheme. Figure 5The diagram shown is an electrical wiring schematic of the junction station in one embodiment of this application. Each outgoing line 1 to 4 is connected to the GIL line and overhead line via corresponding outgoing equipment. The blue portion represents the open-type common single-phase flexible busbar and its connected connection points. When a fault occurs in one phase of the GIL on only one outgoing line, that line is taken out of service, while other circuits operate according to their original wiring. The faulty circuit can be shut down for maintenance.

[0078] When the same phase GIL fails in both outgoing lines, for example, when both outgoing line 1 and outgoing line 2 experience a fault and stop operation, such as... Figure 5 As shown, by adjusting the wiring relationship, the A-phase and B-phase GILs of outgoing line 1 and the B-phase GIL of outgoing line 2 are combined to form a new three-phase outgoing line. Specifically, the two faulty C-phase GILs are taken out of operation. The C-phase overhead line of outgoing line 1 (red line) is connected to the common flexible busbar through the corresponding wiring device, and the B-phase outgoing bushing of outgoing line 2 (red line) is also connected to the common flexible busbar through the wiring device. Thus, the C-phase overhead line of outgoing line 1 is electrically connected to the B-phase GIL of outgoing line 2 through the common flexible busbar, forming a new A, B, and C three-phase operating circuit. Under this operating mode, the relay protection configuration remains unchanged, and the system can still transmit power as required.

[0079] like Figure 6 As shown, Figure 5 The corresponding plan layout diagram of the junction station is shown in the figure. As can be seen, the junction station only has a single common open flexible busbar (blue line) between each outgoing line device. The flexible busbar runs continuously along the outgoing line arrangement direction and is connected to each outgoing line bay via several pillars or supporting components. The arrangement of the single-phase common busbar can be completed without increasing the floor space. The red line in the figure shows the relationship between the faulty phase and its alternative path: the C-phase overhead line of outgoing line 1 is connected to the common flexible busbar through its outgoing bushing and wiring device. After being led out along the outgoing line direction via the flexible busbar, it is connected to the B-phase GIL of outgoing line 2 at the corresponding wiring device, thus forming a new continuous path on the plane.

[0080] The above embodiments illustrate the wiring structure and arrangement of the single-phase common busbar and related switchgear under both substation and receiving station conditions. To ensure that multi-circuit gas-insulated transmission lines operate as backups across circuits, not only is the station-end wiring reasonable, but the potential distribution along the line casing and fault current path also meet operational and protection requirements, this application also includes a specific design for the three-phase busbar structure along the multi-circuit GIL line. The following section combines... Figure 7 The connection method of the three-phase busbar of the multi-circuit GIL enclosure and its configuration under standby operating conditions are explained.

[0081] In some alternative embodiments, after the standby phase scheme of the present application is adopted, each operating phase can serve as a standby phase of another circuit, so the entire three-phase busbar of each circuit needs to be connected. Therefore, along the multi-circuit gas insulated transmission line, a busbar can be provided to electrically connect the outer shells of each phase conductor. The busbar is continuously arranged and electrically connected between multiple circuits and multiple phases, forming an entire three-phase busbar system, and the current carrying capacity is checked according to the maximum operating current when a single circuit is out of operation, to adapt to the operating conditions when the transmission circuit is reorganized by different circuit phase conductors.

[0082] As shown in Figure 7 , it is a schematic diagram of the end short-circuit bus current under normal operating conditions. In the figure, four GIL circuits are taken as an example, A1-C4 represent the GIL conductors of each phase of each circuit, and the red lines represent the three-phase busbar arranged in the pipe gallery and the vertical short-circuit bus connected to the outer shell of each circuit. In each circuit, the A, B, and C three-phase outer shells are connected to the bottom busbar through the vertical short-circuit bus, and the busbar is connected through in the transverse direction of the pipe gallery. Since the sum of the three-phase currents of each circuit is zero under normal operation, the corresponding shell current vector is also zero. Therefore, under normal operating conditions, the current in the pipe gallery busbar collection section (the horizontal section near the ground in the figure) is theoretically zero, and only the combined current of the three-phase outer shell current flowing through each vertical short-circuit bus in each circuit.

[0083] As shown in Figure 8 , it is a schematic diagram of the end short-circuit bus current under fault conditions. Still taking four GIL circuits as an example, assuming that the A phase of the fourth GIL circuit fails and the fourth GIL circuit is out of operation, the remaining three circuits can still bear the entire transmission power under N-1 conditions; then the A phase of the first GIL circuit also fails, and in order to restore the operation of the first GIL circuit as soon as possible, the standby phase switching scheme described in the present application is used to recombine the healthy phases (B1, C1) of the first GIL circuit with the healthy phases (such as B4) of the fourth GIL circuit, and the B phase of the fourth GIL circuit bears the function of the A phase (A1) of the first GIL circuit. At this time, Figure 8 , the end short-circuit bus current distribution is shown. The pipe gallery busbar collection section will carry the return current of the A phase of the first GIL circuit, i.e. no longer zero current. As can be seen, when considering the above N-2 standby operating conditions, the current carrying capacity of the three-phase busbar and the end short-circuit bus needs to be checked and designed according to the maximum operating current when a single circuit is out of operation, to ensure that the busbar system in the pipe gallery can still safely and reliably carry the shell current under the conditions of phase recombination and cross-circuit standby operation.

[0084] In summary, the application can realize mutual standby among GILs of each loop by adding a single-phase common bus and a plurality of disconnectors in the substations or lead-in stations at both ends of the GIL tunnel, without adding device-phase in the tunnel, keeping the cross-sectional size of the GIL tunnel consistent with that without standby phase, and only through switching operation when a fault occurs, thereby effectively resisting N-2 and other adverse conditions. Taking the four-loop GIL in the tunnel as an example, the application can control the number of GILs in the tunnel to 12, maintain the arrangement of four columns and three layers, and maintain the pipe gallery inner diameter of about 11 m, without increasing the number of GILs to 16, lifting the phase spacing and arrangement height as a whole, and increasing the pipe gallery inner diameter to about 12 m, thereby avoiding about one-third of the GIL device usage, and reducing the GIL device investment of about 48 million yuan per kilometer according to 1.2 million yuan per meter, while also avoiding the increase in civil construction cost caused by the increase in the cross section of the pipe gallery; the longer the tunnel length, the more significant the savings in device and civil construction investment.

[0085] It should be noted that, in the present application, the relational terms such as first and second and the like are used solely to distinguish one entity or action from another, without necessarily requiring or implying that there is any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. In the present application, if an action is referred to as being performed "according to" a certain element, it is meant that the action is performed at least according to the element, including the case where the action is performed according to the element alone, and the case where the action is performed according to the element and according to another element. The expressions "a plurality of", "a plurality of times", "a plurality of ways" and the like include 2, 2 times, 2 ways and more than 2, more than 2 times, more than 2 ways.

[0086] The present specification includes the combination of various embodiments described herein. Separate references to embodiments (for example, "an embodiment" or "some embodiments" or "a preferred embodiment"); however, these embodiments are not mutually exclusive, unless indicated as being mutually exclusive or it is clear to a person skilled in the art that they are mutually exclusive. It should be noted that the word "or" is used in the present specification in a non-exclusive sense, unless the context clearly indicates otherwise or requires.

[0087] All documents mentioned in this specification are hereby incorporated by reference in their entirety to provide additional description of the application. In addition, it should be appreciated that the exemplary embodiments of the present application described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions and illustrations herein contain material which is subject to copyright protection. This material may not be further reproduced or used in any manner that constitutes a copyright infringement without the written permission of the owner of this material.

Claims

1. A gas insulated transmission line system supporting multi-circuit mutual backup, comprising a plurality of multi-circuit gas insulated transmission lines arranged between a first station and a second station, each circuit gas insulated transmission line comprising a plurality of phase conductors for transmitting different phase electric energy respectively, characterized in that: a single-phase utility bus capable of being electrically connected to corresponding phase conductors of the multi-circuit gas insulated transmission lines simultaneously is arranged at the outgoing side of the first station and the second station; for each phase conductor of each circuit of the multi-circuit gas insulated transmission lines, a first switching device for connecting the phase conductor to a station internal equipment and a second switching device for connecting the phase conductor to the single-phase utility bus are arranged in the first station and the second station respectively; the system is configured to, when a first circuit gas insulated transmission line has been in a working condition of exiting operation, a phase conductor of a second circuit fails and there is at least one healthy phase conductor of the second circuit, make the healthy phase conductor of the second circuit replace the failed phase conductor of the first circuit to participate in forming a three-dimensional transmission circuit through the single-phase utility bus by operating corresponding switching devices, so as to realize cross-circuit mutual backup between the multi-circuit gas insulated transmission lines in an N-2 working condition; for each phase, all phase conductors of the phase in the multi-circuit gas insulated transmission lines are only electrically connected to the single-phase utility bus corresponding to the phase through the respective second switching device, so that when any circuit of the same phase fails, other circuits can realize mutual backup through the corresponding single-phase utility bus.

2. The multi-circuit, mutually backed-up, gas-insulated power transmission line system of claim 1, wherein, the operation of the corresponding switching devices comprises: when the phase conductor of the gas insulated transmission line of the second circuit is detected to fail, the first switching device and the second switching device corresponding to the failed phase conductor of the circuit are controlled to be opened, so that the failed phase conductor exits operation; selecting another healthy phase conductor of the second circuit, closing the second switching device between the healthy phase conductor and the single-phase utility bus, making the healthy phase conductor electrically connected to the station internal equipment through the single-phase utility bus, and by closing the corresponding first switching device, the healthy phase conductor replaces the failed phase conductor of the first circuit to perform the transmission function in the three-dimensional transmission circuit, and at the same time, the first switching device and the second switching device corresponding to the remaining non-replaced phase conductors of the second circuit are opened.

3. The multi-circuit, mutually backed-up, gas-insulated power transmission line system of claim 1, wherein, the single-phase utility bus is arranged corresponding to three phases respectively in the first station and / or the second station, for realizing mutual backup between the multi-circuits when any phase of the three phases fails.

4. The multi-circuit, mutually backed-up, gas-insulated power transmission line system of claim 1, wherein, the first switching device and the second switching device are switching assemblies containing isolation function, and an electrical and / or logical interlock is arranged between the first switching device and the second switching device corresponding to the same phase conductor, for preventing unexpected closing of the two.

5. The multi-circuit, mutually backed-up, gas-insulated power transmission line system of claim 4, wherein, The disconnector and grounding switch for switching the phase conductors as backup are respectively provided with independent measuring and control devices, the measuring and control devices are in information interaction with the measuring and control devices in the outgoing line interval through a communication network, the actual position state of the switch device and the grounding switch is collected, and the electrical and / or logical interlocking between the first switch device and the second switch device is cooperatively controlled based on the position state.

6. The multi-circuit, mutually backed-up, gas insulated electric transmission line system of claim 1, wherein, Two sets of short line protection devices are arranged at each outgoing line of the first station and the second station, The short line protection devices are respectively used for protecting the short line section which is still in the live state when the loop operation is formed by the switch in the station after the line outgoing line is isolated.

7. The multi-circuit, mutually backed-up, gas insulated electric transmission line system of claim 1, wherein, The first station and / or the second station is a substation adopting GIS arrangement, and in the substation: Two groups of the switch devices are arranged in the GIS interval for each outgoing line, wherein the switch devices are used for connecting the phase conductors of the outgoing line to the GIS bus, and the other group of the switch devices is used for connecting the phase conductors of the outgoing line to the single-phase public bus of the corresponding phase; The single-phase public bus is arranged in a vertical column relative to the GIS bus, the switch devices for connecting to the single-phase public bus are vertically arranged on both sides of the GIS interval, And the outgoing line circuit breaker and the switch device cooperating with the outgoing line circuit breaker are devices for separate-phase operation, so as to complete the arrangement of the single-phase public bus and the corresponding switch device without increasing the size of the GIS room.

8. The multi-circuit, mutually backed-up, gas insulated transmission line system of claim 1, wherein, The first station and / or the second station is a lead-in station, and in the lead-in station: The single-phase public bus for realizing the backup connection of the phase conductors adopts an open soft bus arrangement, the open soft bus is in a non-live state in the normal operation state, and the voltage transformer and the current transformer corresponding to the open soft bus adopt an open arrangement.

9. The multi-circuit, mutually backed-up, gas insulated transmission line system of claim 1, wherein, Busbars are arranged along the multi-loop gas insulated transmission line to electrically connect the housings of the phase conductors, the busbars are continuously arranged and electrically connected between the multiple loops and the multiple phases, form a three-phase busbar system connected as a whole, and are verified for current carrying capacity according to the maximum operating current when a single loop is out of operation, so as to adapt to the operating conditions when the power transmission circuit is reorganized through different phase conductors.

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