Starting method of multi-terminal flexible dc grid interconnection pole line circuit breaker when disabled

Abstract

The application discloses a starting method for multi-terminal flexible DC power grid interconnection pole line circuit breaker when being disabled, comprising the following steps: sequentially converting each interconnection grounding device, interconnection and corresponding metal return line of a new energy island station, pole line-4 switch, interconnection and corresponding positive and negative poles of a new energy island station, and positive and negative poles of the interconnection except special poles into an operating state, sequentially starting positive and negative pole converters of each interconnection and corresponding positive and negative pole converters of a new energy island station, and converting the interconnection metal return line into an operating state and stopping the redundant in-station grounding device; then sequentially starting the converter according to the order of special poles of a special interconnection, corresponding poles of a new energy island station corresponding to the special interconnection, and connecting the poles of the flexible DC power grid except the special poles of the special interconnection; finally, adjusting the power control mode of the interconnection to be bipolar power control, connecting the metal return line and the positive and negative poles between the new energy island stations, and connecting the new energy island station to the new energy plant station for power transmission.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission system technology, and more specifically, to a method for starting up a multi-terminal flexible DC grid interconnection line circuit breaker when it is disabled. Background Technology

[0002] Modular multilevel converters (MMCs) have been widely used in regional power grid interconnection and the transmission of isolated new energy sources due to their advantages such as high modularity and low harmonic content. In recent years, with the completion and commissioning of multi-terminal flexible DC transmission projects such as the Zhangbei flexible DC transmission project, high-voltage DC circuit breakers (HVDCs) have been gradually applied to engineering sites. Because HVDCs employ complex topologies and have a large number of power electronic devices, their failure rate is relatively high, indirectly causing the flexible DC transmission system to fail to deliver power normally. Therefore, the start-up and shutdown of multi-terminal flexible DC transmission projects when the pole-line DC circuit breakers are unavailable has become an urgent problem to be solved in the operation of such projects, seriously affecting the availability of the project. Currently, when a multi-terminal flexible DC transmission project experiences a situation where the DC line HVDC circuit breaker cannot be put into normal operation, dispatching and operation personnel generally can only operate the corresponding DC line and DC circuit breaker to the maintenance state and wait for the troubleshooting work to be completed before power can be restored. High-voltage DC circuit breakers are used in large numbers in multi-terminal flexible DC transmission projects, and their failure rate is relatively high. Failures of high-voltage circuit breakers on DC lines have frequently forced the suspension of power transmission in multiple DC transmission projects, seriously affecting the safe and stable operation of the power grid. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a startup method for inter-station pole line circuit breakers in multi-terminal flexible DC grids when they are disabled.

[0004] According to one aspect of the present invention, a method for starting a multi-terminal flexible DC grid interconnection line circuit breaker when it is disabled is provided, comprising:

[0005] The grounding devices of each interconnected station of the multi-terminal flexible DC grid, the metal return lines of the interconnected station and the corresponding new energy island station, the pole line-4 disconnect switch, the positive and negative pole lines of the interconnected station and the corresponding new energy island station, and the positive and negative poles of the interconnected station except for the special pole are sequentially switched to the operating state. The positive and negative pole converters of each interconnected station and their corresponding new energy island station are started sequentially. The metal return lines between interconnected stations are switched to the operating state and the redundant in-station grounding devices are shut down, thus completing the end-to-end start-up of multiple interconnected stations and their corresponding new energy island stations except for the special pole.

[0006] After multiple interconnected stations and their corresponding new energy island stations are started end-to-end except for special poles, the converters are started in the order of special poles of special interconnected stations and corresponding poles of new energy island stations corresponding to special interconnected stations. The pole lines of both ends of the flexible DC grid are connected except for the special poles of special interconnected stations, thus completing the end-to-end start-up of special interconnected stations and their corresponding new energy island stations.

[0007] After the special interconnected power station and the corresponding special extreme end of the new energy island station are started, the power control mode of the interconnected power station is adjusted to bipolar power control, the metal return line and positive and negative pole lines between the new energy island stations are connected, and the new energy island stations are connected to the new energy power plants for power supply, thus completing the pole line connection between multiple new energy island stations and the power supply to the new energy power plants.

[0008] Optionally, the grounding devices of each interconnected power station, the metallic return lines between the interconnected power station and the corresponding new energy islanded station, the pole-4 disconnectors, the positive and negative pole lines between the interconnected power station and the corresponding new energy islanded station, and the positive and negative poles of the interconnected power station (excluding special poles) are sequentially switched to the operating state. The positive and negative pole converters of each interconnected power station and their corresponding new energy islanded station are then started sequentially. The metallic return lines between interconnected power stations are switched to the operating state, and redundant in-station grounding devices are shut down. This completes the end-to-end startup of multiple interconnected power stations and their corresponding new energy islanded stations (excluding special poles), including:

[0009] Following the order of grounding points from nearest to farthest, the metal return lines between the interconnected network and the corresponding new energy island stations are switched to operational status.

[0010] Then close the DC positive and negative lines of each interconnecting station and the new energy island station to switch the DC positive and negative lines of the interconnecting station and the corresponding new energy island station to the operating state.

[0011] Then, except for the special poles, the positive and negative poles of the interconnected network are converted to constant DC voltage control and constant reactive power control;

[0012] Then, all poles of the network except for the special poles are converted to network connections;

[0013] Then, all terminals except the special terminal are charged and unlocked by the converter.

[0014] Then, except for special poles, the other poles of the new energy island station corresponding to the connected station are unlocked and the AC side circuit breaker of the converter is switched to the operating state;

[0015] Then, the inter-site metal loopback is switched to running status;

[0016] Finally, only one interconnected power station's grounding device is kept in operation, while the grounding devices of the remaining interconnected power stations are switched to hot standby, completing the end-to-end startup of multiple interconnected power stations and their corresponding new energy island stations, except for special poles.

[0017] Optionally, the converter is started in the order of special pole of special interconnection station and corresponding pole of new energy islanding station, and the pole lines of both ends of the flexible DC grid except for the special pole of special interconnection station are connected to complete the end-to-end start-up of special interconnection station and corresponding new energy islanding station, including:

[0018] Switch the bypass isolating switch corresponding to the special interconnection pole line circuit breaker of the multi-terminal flexible DC power grid to the operating state;

[0019] Then, the special electrode is switched to constant DC voltage control mode and constant reactive power control mode, and the special electrode is connected to the network. After the special electrode is charged, it is unlocked and put into operation.

[0020] Then, the corresponding pole of the new energy island station corresponding to the special connection station is switched to a constant frequency and constant AC voltage control mode, and the pole is switched to an island connection state;

[0021] Then, the DC circuit breaker of the corresponding pole line of the special interconnection site between the special interconnection site and the corresponding new energy island station is switched to the operating state;

[0022] Then, the circuit breaker of the positive line of the island station between the special connection station and the corresponding new energy island station is switched to the operating state, and is unlocked and operated after the unlocking conditions are met, and the AC bus side switch of the pole converter is switched to the operating state.

[0023] Then switch the circuit breakers on both sides of the DC positive and negative lines of the station opposite the faulty pole line of the faulty connection site to the operating state;

[0024] Finally, the special interconnection site pole-to-pole circuit breaker is switched to operating status, completing the special interconnection site and the corresponding new energy island station special extreme end start-up.

[0025] Optionally, the final power control mode of the interconnected power station is adjusted to bipolar power control, connecting the metal return lines and positive and negative lines between the new energy islanded stations, and connecting the new energy islanded stations to the new energy power plants for power supply, thus completing the connection of the pole lines between multiple new energy islanded stations and the power supply to the new energy power plants, including:

[0026] The active power control mode of the AC interconnection station of the multi-terminal flexible DC grid is changed to bipolar power control.

[0027] Then, the metal return line between the new energy island stations is switched to operational status;

[0028] Then, the high-voltage DC circuit breakers on both sides of the positive and negative DC lines between the new energy island stations are switched to the operating state;

[0029] Then, the isolated new energy power station will be connected to a new energy power plant for power generation.

[0030] The notification indicates that the automatic power control curve of the AC connection website has been put into automatic control, completing the pole line connection between multiple new energy island stations and the power supply of new energy power plants.

[0031] According to another aspect of the present invention, a starting device is provided when a multi-terminal flexible DC grid interconnection line circuit breaker is disabled, comprising:

[0032] The first startup module is used to sequentially switch the grounding devices of each interconnected station of the multi-terminal flexible DC grid, the metal return lines of the interconnected station and the corresponding new energy island station, the pole line-4 disconnect switch, the positive and negative pole lines of the interconnected station and the corresponding new energy island station, and the positive and negative poles of the interconnected station except for the special poles, to the operating state. It also sequentially starts the positive and negative pole converters of each interconnected station and their corresponding new energy island station, switches the metal return lines between interconnected stations to the operating state, and shuts down the redundant in-station grounding devices, thus completing the end-to-end startup of multiple interconnected stations and their corresponding new energy island stations except for the special poles.

[0033] The second startup module is used to start the converter in the order of special pole of special interconnection site and corresponding pole of new energy island station corresponding to special interconnection site, and connect the pole lines of the two ends of the flexible DC grid except for the special pole of special interconnection site, to complete the startup of special pole of special interconnection site and corresponding new energy island station.

[0034] The module is used to adjust the power control mode of the interconnected power station to bipolar power control, connect the metal return lines and positive and negative lines between the new energy islanded stations, and connect the new energy islanded stations to the new energy power plants for power supply, thus completing the connection of the pole lines between multiple new energy islanded stations and the power supply to the new energy power plants.

[0035] According to another aspect of the present invention, a computer-readable storage medium is provided, the storage medium storing a computer program for performing the methods described in any of the above aspects of the present invention.

[0036] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0037] Therefore, based on actual cases encountered in the operation of flexible DC transmission projects, this application clearly defines the startup and dispatching operation steps for multi-terminal flexible DC transmission projects when the DC line circuit breaker between two AC interconnected stations is unavailable. First, the grounding devices of each interconnected station, the metal return lines between the interconnected station and the corresponding new energy islanding station, the pole-4 disconnectors, the positive and negative pole lines between the interconnected station and the corresponding new energy islanding station, and the positive and negative poles of the interconnected station (excluding special poles) are sequentially switched to the operating state. Then, the positive and negative pole converters of each interconnected station and their corresponding new energy islanding station are started sequentially. Finally, the metal return lines between the interconnected stations are switched to the operating state and shut down. The redundant grounding devices within the stations are used to complete end-to-end startup of multiple interconnected power stations and their corresponding renewable energy islanded stations, except for special poles. Then, the converters are started in the order of special poles of the special interconnected power stations and corresponding poles of the renewable energy islanded stations. The pole lines at both ends of the flexible DC grid, except for the special poles of the special interconnected power stations, are connected to complete end-to-end startup of the special interconnected power stations and their corresponding renewable energy islanded stations. Finally, the power control mode of the interconnected power stations is adjusted to bipolar power control, the metallic return lines and positive and negative pole lines between the renewable energy islanded stations are connected, and the renewable energy islanded stations are connected to renewable energy power plants for power supply, completing the pole line connection between multiple renewable energy islanded stations and the power supply to renewable energy power plants. This operation method ensures the normal operation of the flexible DC system under such conditions, providing a guarantee for the safety and stability of the power grid. Attached Figure Description

[0038] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0039] Figure 1 This is a flowchart illustrating a method for starting a multi-terminal flexible DC grid interconnection inter-station pole line circuit breaker when it is disabled, provided in an exemplary embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the topology of a four-terminal flexible DC transmission system provided in an exemplary embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of a common topology and switch numbering of a flexible DC converter station provided in an exemplary embodiment of the present invention;

[0042] Figure 4 This is a flowchart of the startup process of a four-terminal flexible DC transmission system provided by an exemplary embodiment of the present invention;

[0043] Figure 5 This is a flowchart of the startup process of a multi-terminal flexible DC transmission system provided by an exemplary embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of the positive electrode connection state provided by an exemplary embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram of the structure of the starting device when the multi-terminal flexible DC grid interconnection inter-station pole line circuit breaker is disabled, provided in an exemplary embodiment of the present invention;

[0046] Figure 8 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. Detailed Implementation

[0047] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0048] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0049] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0050] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0051] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0052] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0053] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0054] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0055] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0056] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0057] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0058] The embodiments of this invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate together with a wide range of other general-purpose or special-purpose computing system environments or configurations. Well-known examples of terminal devices, computing systems, environments, and / or configurations suitable for use with terminal devices, computer systems, servers, and other electronic devices include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments including any of the above systems, etc.

[0059] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in distributed cloud computing environments, where tasks are executed by remote processing devices linked through communication networks. In distributed cloud computing environments, program modules can reside on local or remote computing system storage media, including storage devices.

[0060] Exemplary methods

[0061] Figure 1 This is a flowchart illustrating a method for starting a multi-terminal flexible DC grid interconnection inter-station pole line circuit breaker when it is disabled, provided in an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as... Figure 1 As shown, the starting method 100 for multi-terminal flexible DC grid interconnection inter-station pole line circuit breakers when disabled includes the following steps:

[0062] Step 101: Sequentially switch the grounding devices of each interconnected station, the metal return lines of the interconnected station and the corresponding new energy islanded station, the pole line-4 disconnect switch, the positive and negative pole lines of the interconnected station and the corresponding new energy islanded station, and the positive and negative poles of the interconnected station except for the special poles, to the operating state of each interconnected station. Then, sequentially start the positive and negative pole converters of each interconnected station and their corresponding new energy islanded station, switch the metal return lines between interconnected stations to the operating state, and shut down the redundant in-station grounding devices, thus completing the end-to-end startup of multiple interconnected stations and their corresponding new energy islanded stations except for the special poles.

[0063] Optionally, the grounding devices of each interconnected power station, the metallic return lines between the interconnected power station and the corresponding new energy islanded station, the pole-4 disconnectors, the positive and negative pole lines between the interconnected power station and the corresponding new energy islanded station, and the positive and negative poles of the interconnected power station (excluding special poles) are sequentially switched to the operating state. The positive and negative pole converters of each interconnected power station and their corresponding new energy islanded station are then started sequentially. The metallic return lines between interconnected power stations are switched to the operating state, and redundant in-station grounding devices are shut down. This completes the end-to-end startup of multiple interconnected power stations and their corresponding new energy islanded stations (excluding special poles), including:

[0064] Following the order of grounding points from nearest to farthest, the metal return lines between the interconnected network and the corresponding new energy island stations are switched to operational status.

[0065] Then close the DC positive and negative lines of each interconnecting station and the new energy island station to switch the DC positive and negative lines of the interconnecting station and the corresponding new energy island station to the operating state.

[0066] Then, except for the special poles, the positive and negative poles of the interconnected network are converted to constant DC voltage control and constant reactive power control;

[0067] Then, all poles of the network except for the special poles are converted to network connections;

[0068] Then, all terminals except the special terminal are charged and unlocked by the converter.

[0069] Then, except for special poles, the other poles of the new energy island station corresponding to the connected station are unlocked and the AC side circuit breaker of the converter is switched to the operating state;

[0070] Then, the inter-site metal loopback is switched to running status;

[0071] Finally, only one interconnected power station's grounding device is kept in operation, while the grounding devices of the remaining interconnected power stations are switched to hot standby, completing the end-to-end startup of multiple interconnected power stations and their corresponding new energy island stations, except for special poles.

[0072] Step 102: After multiple interconnected power stations and their corresponding new energy islanded stations are started end-to-end except for special poles, the converters are started in the order of special poles of special interconnected power stations and corresponding poles of new energy islanded stations corresponding to special interconnected power stations. The pole lines of both ends of the flexible DC grid are connected except for the special poles of special interconnected power stations, thus completing the end-to-end start-up of special interconnected power stations and their corresponding new energy islanded stations.

[0073] Optionally, the converter is started in the order of special pole of special interconnection station and corresponding pole of new energy islanding station, and the pole lines of both ends of the flexible DC grid except for the special pole of special interconnection station are connected to complete the end-to-end start-up of special interconnection station and corresponding new energy islanding station, including:

[0074] Switch the bypass isolating switch corresponding to the special interconnection pole line circuit breaker of the multi-terminal flexible DC power grid to the operating state;

[0075] Then, the special electrode is switched to constant DC voltage control mode and constant reactive power control mode, and the special electrode is connected to the network. After the special electrode is charged, it is unlocked and put into operation.

[0076] Then, the corresponding pole of the new energy island station corresponding to the special connection station is switched to a constant frequency and constant AC voltage control mode, and the pole is switched to an island connection state;

[0077] Then, the DC circuit breaker of the corresponding pole line of the special interconnection site between the special interconnection site and the corresponding new energy island station is switched to the operating state;

[0078] Then, the circuit breaker of the positive line of the island station between the special connection station and the corresponding new energy island station is switched to the operating state, and is unlocked and operated after the unlocking conditions are met, and the AC bus side switch of the pole converter is switched to the operating state.

[0079] Then switch the circuit breakers on both sides of the DC positive and negative lines of the station opposite the faulty pole line of the faulty connection site to the operating state;

[0080] Finally, the special interconnection site pole-to-pole circuit breaker is switched to operating status, completing the special interconnection site and the corresponding new energy island station special extreme end start-up.

[0081] Step 103: After the special interconnected station and the corresponding special extreme end of the new energy island station are started, the power control mode of the interconnected station is adjusted to bipolar power control, the metal return line and positive and negative pole lines between the new energy island stations are connected, and the new energy island stations are connected to the new energy power plants for power supply, thus completing the pole line connection between multiple new energy island stations and the power supply to the new energy power plants.

[0082] Optionally, the final power control mode of the interconnected power station is adjusted to bipolar power control, connecting the metal return lines and positive and negative lines between the new energy islanded stations, and connecting the new energy islanded stations to the new energy power plants for power supply, thus completing the connection of the pole lines between multiple new energy islanded stations and the power supply to the new energy power plants, including:

[0083] The active power control mode of the AC interconnection station of the multi-terminal flexible DC grid is changed to bipolar power control.

[0084] Then, the metal return line between the new energy island stations is switched to operational status;

[0085] Then, the high-voltage DC circuit breakers on both sides of the positive and negative DC lines between the new energy island stations are switched to the operating state;

[0086] Then, the isolated new energy power station will be connected to a new energy power plant for power generation.

[0087] The notification indicates that the automatic power control curve of the AC connection website has been put into automatic control, completing the pole line connection between multiple new energy island stations and the power supply of new energy power plants.

[0088] Specifically, this invention is applicable to multi-terminal start-up in multi-terminal flexible DC transmission systems with four or more terminals, including AC interconnected stations and new energy islanded stations, where the pole line DC circuit breaker between two AC interconnected stations is unavailable.

[0089] The following section uses a four-terminal flexible DC transmission system as an example to illustrate the startup method when the DC circuit breaker between the AC interconnecting stations is unavailable. The startup method for multiple stations follows the same logic. The topology of the four-terminal flexible DC transmission system is shown in the figure below. The AC sides of the AC stations are connected to the AC power grid (hereinafter referred to as interconnecting stations), while the AC sides of the BD stations are connected to a renewable energy power island, requiring voltage support from the flexible DC converter stations (hereinafter referred to as islanded stations). The DC sides of the four converter stations are connected in a ring network via positive lines, negative lines, and metallic return lines. When... Figure 2 When any DC circuit breaker is in an unavailable state, the method of the present invention can be used to start or stop it.

[0090] The topology of a single converter station and the relevant circuit breaker disconnector numbers are as follows: Figure 3 As shown, the four-terminal starting method proposed in this invention refers to the starting method when the positive and negative pole high-voltage DC circuit breakers (i.e., P1D, P2D, N1D or N2D) between two AC interconnecting stations are in an unavailable state, which is called the unavailable starting method of interconnecting station pole DC circuit breakers.

[0091] When the DC circuit breaker between the two stations is unavailable, refer to Figure 4 As shown, the startup steps of the flexible DC transmission system are as follows:

[0092] Initial setup: The positive and negative poles, DC bus, DC lines, and metallic return lines of each converter station are all in cold standby mode (cold standby mode means that the circuit breaker and the isolating switches on both sides of the circuit breaker are in the open state), the AC side switches of the converter are in cold standby mode, and stations B and D are in cold standby mode; the high-voltage DC circuit breakers of the positive and negative DC lines between the two stations are not available (cold standby or under maintenance).

[0093] (1) Grounding device A is switched to operating state, and grounding device C is switched to operating state.

[0094] (2) All metal return lines at stations AB and CD are switched to operating status. Operation sequence: AB (A first, then B), CD (C first, then D), that is, in the order of the grounding points from near to far.

[0095] (3) Close the DC positive and negative line-4 disconnect switches of each station (there is no order in the operation of the line disconnect switches of each station).

[0096] (4) The DC circuit breakers of the DC positive and negative lines of AB and CD that do not involve the unusable high voltage DC circuit breakers are switched to the operating state (if the high voltage DC circuit breaker of the AC positive line of station A is unusable, then the DC positive line circuit breaker of AB will not operate) (no order).

[0097] (5) The active power control mode of both positive and negative poles of stations A and C is switched to constant DC voltage control, and the reactive power control mode is switched to constant reactive power control.

[0098] (6) Except for the corresponding pole of the high voltage DC circuit breaker of the corresponding pole line of station A and station C that is in an unavailable state (for example, if the high voltage DC circuit breaker of the AC positive pole line of station A is unavailable, then the positive pole of station A will not be operated), all other poles are switched to network connection.

[0099] (7) At stations A and C, except for the corresponding poles of the high voltage DC circuit breakers that are in an unavailable state, the converters of the other poles are charged and unlocked.

[0100] (9) Except for the corresponding pole of the high voltage DC circuit breaker of the corresponding pole line that is in an unavailable state, the other poles of B and D are switched to islanded unlocking and the AC bus side switch of the converter of that pole is switched to the operating state; there is no requirement for the order of operation of switching D and B to the operating state.

[0101] (10) The AC metal return line is switched to the operating state (the grounding device in the station that is connected to M1D or M2D will be switched to hot standby).

[0102] (11) The grounding device of station A is switched to hot standby or the grounding device of station C is switched to hot standby (selected according to the dispatching and operation requirements; the station with the metal return circuit breaker closed after closing will switch the grounding device in the station to hot standby).

[0103] (12) Switch the bypass isolating switch corresponding to the high voltage DC circuit breaker that is in an unavailable state at a special station to the operating state (for example, if P1D is unavailable, close the P1D-3 switch).

[0104] (13) The active power control mode of the special station and the special pole is switched to the constant DC voltage control mode, the reactive power control mode is the constant reactive power control mode, the special pole is connected to the network, and the special pole is unlocked and operated after charging.

[0105] (14) The active power control mode of the new energy island station corresponding to the special station is changed to the fixed frequency control mode, and the reactive power control mode is the fixed AC voltage control mode. The active power control mode of the pole is changed to bipolar power control, and the pole is switched to island connection state (DC starting resistor is in the connected state).

[0106] (15) The high-voltage DC circuit breaker of the corresponding pole of the special station between the special station and the new energy island station is switched to the operating state (if the special station is A, then the corresponding new energy island station is B; if the special station is C, then the corresponding new energy island station is D).

[0107] (16) The high voltage DC circuit breaker of the DC positive line of the new energy island station between the special station and the new energy island station is put into operation. The corresponding pole of the new energy island station is fully charged and unlocked after the unlocking conditions are met. The AC bus side switch of the converter of that pole is put into operation.

[0108] (17) The high-voltage DC circuit breakers on both sides of the DC positive and negative lines of the special station and the special pole line are switched to the operating state (i.e., P1D, P2D, N1D or N2D are switched to the operating state) (no order).

[0109] (18) The special station special pole line to pole line high voltage DC circuit breaker is switched to the operating state.

[0110] (At this time, the active power control mode of the special station automatically switches to constant active power control.)

[0111] (19) Station A’s positive and negative active power control mode is switched to bipolar power control.

[0112] (20) BD metal loop returns to running state (no sequence).

[0113] (21) The high-voltage DC circuit breakers on both sides of the positive and negative DC lines of BD are switched to the operating state (no sequence).

[0114] (22) Stations B and D switch off their station service transformers, and switch their energy-consuming transformers and energy-consuming devices to the operating state.

[0115] (23) Power generation from new energy power plants.

[0116] (24) Notify Station A to put the automatic power control curve into automatic control.

[0117] The following is based on Figure 2 Taking the four-terminal flexible DC transmission system shown as an example, the non-standard four-terminal startup procedure is described in detail when the positive and negative high-voltage DC circuit breakers between the two power stations cannot be put into use. (Refer to...) Figure 5 As shown:

[0118] 1. The high-voltage DC switch for the AC-DC positive line at Station A cannot be put into use.

[0119] Initial setup: The positive and negative poles, DC buses, DC lines, and metallic return lines of each converter station are all in cold standby mode (cold standby mode means that the circuit breakers and the isolating switches on both sides of the circuit breakers are in the open state), the AC side switches of the converters are in cold standby mode, the AC buses of stations B and D are in cold standby mode, and the bus tie and sectionalizing switches are closed; the high-voltage DC circuit breaker of the AC DC positive pole line of station A is not available (cold standby or under maintenance).

[0120] (1) Grounding device A is switched to operating state, and grounding device C is switched to operating state.

[0121] (2) All metal return lines at stations AB and CD are switched to operating status. Operation sequence: AB (A first, then B), CD (C first, then D), that is, in the order of the grounding points from near to far.

[0122] (3) Close the DC positive and negative line-4 disconnect switches of each station (there is no order in the operation of the line disconnect switches of each station).

[0123] (4) The high-voltage DC circuit breakers on both sides of the positive and negative DC lines of CD are switched to the operating state (without any sequence).

[0124] (5) The high-voltage DC circuit breakers on both sides of the AB DC negative line are switched to the operating state (no sequence).

[0125] (6)Reference Figure 6 As shown, the active power control mode of the positive and negative poles of station D is switched to constant frequency control mode, the reactive power control mode is switched to constant AC voltage control mode, the active power control mode of the positive and negative poles is switched to bipolar power control, and the positive and negative poles are switched to a reverse connection state.

[0126] Bilibili switched from negative active power control mode to constant frequency control mode, reactive power control mode to constant AC voltage control mode, negative active power control mode to bipolar power control, and negative pole to islanded connection state.

[0127] There is no specific order required for the operations of transferring D-site and B-site to isolated islands.

[0128] (7) Station C’s positive and negative active power control mode is switched to constant DC voltage control mode, reactive power control mode is switched to constant reactive power control mode, and positive and negative poles are switched to running state (first positive and negative poles are switched to network connection, then positive and negative poles are charged, and finally positive and negative poles are unlocked and run).

[0129] Station A switches from active power control mode to constant DC voltage control mode and reactive power control mode to constant reactive power control mode. The negative terminal is reversed for connection, the negative terminal is charged, and the negative terminal is unlocked for operation.

[0130] There is no specific order required for switching Station C and Station A to operational status.

[0131] (8) Verify that the positive and negative terminals of station D have completed charging and are ready to be unlocked; the negative terminal of station B has completed charging and is ready to be unlocked.

[0132] (9) When the positive and negative poles of station D are switched to islanded mode and unlocked, the AC bus side switch of the positive converter is switched to the running state, and the AC bus side switch of the negative converter is switched to the running state.

[0133] Bilibili negative pole to island unlock (i.e., unlock in island connection state), negative pole converter AC bus side switch to operation state;

[0134] There is no specific order required for switching D-site and B-site to running status.

[0135] (10) The AC metal return line is switched to the operating state (the grounding device in the station that is connected to MBS will be switched to hot standby).

[0136] (11) The grounding device of station C is switched to hot standby or the grounding device of station A is switched to hot standby (selected according to the dispatching and operation requirements; the grounding device of the station that is later merged with MBS will be switched to hot standby).

[0137] (12) The high voltage DC circuit breaker of the AC DC positive line of Station A is in bypass operation (P1D-3 is switched to operation).

[0138] (13) Station A’s positive active power control mode is switched to constant DC voltage control mode, and the reactive power control mode is constant reactive power control mode. The positive pole is switched to the running state (first the positive pole is switched to network connection, then the positive pole is charged, and finally the positive pole is unlocked and running).

[0139] (14) Station B's positive active power control mode is switched to constant frequency control mode, the reactive power control mode is constant AC voltage control mode, the positive active power control mode is switched to bipolar power control, and the positive pole is switched to islanded connection state (note that the DC starting resistor is in the connected state).

[0140] (15) The high voltage DC switch of the AB positive line of station A is switched to the running state.

[0141] (16) The high voltage DC switch of the AB DC positive line of station B is switched to the running state. Station B's positive charging is completed. After the unlocking conditions are met, the switch is unlocked and put into operation. The AC bus side switch of the positive converter is switched to the running state.

[0142] (17) The high-voltage DC switches on both sides of the AC DC positive and negative lines of station C are switched to the operating state (without any sequence).

[0143] (18) The high voltage DC switch of the AC DC negative line of station A is switched to the running state.

[0144] (At this time, the active power control mode of station A automatically switches to constant active power control.)

[0145] (19) to (24) are general steps and are the same as those described above.

[0146] 2. The high-voltage DC switch for the AC / DC negative line at Station A cannot be put into use.

[0147] Initial setup: The positive and negative poles, DC buses, DC lines, and metallic return lines of each converter station are all in cold standby mode. The AC side switches of the converters are in cold standby mode. The AC buses of stations B and D are in cold standby mode. The bus tie and sectionalizing switches are closed. The high-voltage DC switch of the AC DC negative pole line of station A is unavailable (cold standby or under maintenance).

[0148] (1) to (11) are general steps and are the same as those described above.

[0149] (12) The high voltage DC switch of the AC DC negative line of station A is in bypass operation (N1D-3 is switched to operation).

[0150] (13) Station A’s negative active power control mode is switched to constant DC voltage control mode, and the reactive power control mode is constant reactive power control mode. The negative terminal is switched to the running state (first the negative terminal is switched to network connection, then the negative terminal is charged, and finally the negative terminal is unlocked and run).

[0151] (14) Station B’s negative active power control mode is switched to constant frequency control mode, reactive power control mode is constant AC voltage control mode, negative active power control mode is switched to bipolar power control, and negative is switched to islanded connection state (note that the DC starting resistor is in the connected state).

[0152] (15) The high voltage DC switch of the AB DC negative line of station A is switched to the running state.

[0153] (16) The high voltage DC switch of the AB DC negative line of station B is switched to the running state. Station B's negative pole charging is completed. After the unlocking conditions are met, the station is unlocked and put into operation. The AC side incoming line switch of the negative pole converter is switched to the running state.

[0154] (17) The high-voltage DC switches on both sides of the AC DC positive and negative lines of station C are switched to the operating state (without any sequence).

[0155] (18) The high voltage DC switch of the AC DC positive line of station A is switched to the running state.

[0156] (At this time, the active power control mode of station A automatically switches to constant active power control.)

[0157] (19) to (24) are general steps and are the same as those described above.

[0158] 3. The high-voltage DC switch of the AC-DC positive line at station C cannot be put into use.

[0159] Initial setup: The positive and negative poles, DC buses, DC lines, and metallic return lines of each converter station are all in cold standby mode. The AC side switches of the converters are in cold standby mode. The AC buses of stations B and D are in cold standby mode. The bus tie and sectionalizing switches are closed. The high-voltage DC switch of the AC DC positive line of station C is unavailable (cold standby or under maintenance).

[0160] (1) to (11) are general steps and are the same as those described above.

[0161] (12) The high voltage DC switch of the AC DC positive line of station C is in bypass operation (P1D-3 is switched to operation).

[0162] (13) The active power control mode of the positive pole of station C is switched to constant DC voltage control mode, the reactive power control mode is constant reactive power control mode, and the positive pole is switched to the running state (first the positive pole is switched to network connection, then the positive pole is charged, and finally the positive pole is unlocked and operated).

[0163] (14) The active power control mode of station D is changed to constant frequency control mode, the reactive power control mode is constant AC voltage control mode, the active power control mode of the positive pole is changed to bipolar power control, and the positive pole is changed to islanded connection state (note that the DC starting resistor is in the connected state).

[0164] (15) The high voltage DC switch of the DC positive line of station C CD is switched to the running state.

[0165] (16) The high voltage DC switch of the DC positive line of station D is switched to the running state. Station D is fully charged and unlocked after the conditions for unlocking are met. The AC side incoming line switch of the positive converter is switched to the running state.

[0166] (17) The high-voltage DC switches on both sides of the AC DC negative line are switched to the operating state (no sequence).

[0167] (18) The high voltage DC switch of the AC DC positive line of station A is switched to the running state.

[0168] (At this time, the active power control mode of the positive and negative poles of station A automatically switches to constant active power control.)

[0169] (19) to (24) are general steps and are the same as those described above.

[0170] 4. The high-voltage DC switch on the AC / DC negative line of Station C cannot be put into use.

[0171] Initial setup: The positive and negative poles, DC buses, DC lines, and metallic return lines of each converter station are all in cold standby mode. The AC side switches of the converters are in cold standby mode. The AC buses of stations B and D are in cold standby mode. The bus tie and sectionalizing switches are closed. The high-voltage DC switch of the AC DC negative pole line of station C is unavailable (cold standby or under maintenance).

[0172] (1) to (11) are general steps and are the same as those described above.

[0173] (12) The high voltage DC switch of the AC DC negative line of station C is in bypass operation (N1D-3 is switched to operation).

[0174] (13) The active power control mode of the negative pole of station C is switched to constant DC voltage control mode, the reactive power control mode is constant reactive power control mode, and the negative pole is switched to the running state (first the negative pole is switched to network connection, then the negative pole is charged, and finally the negative pole is unlocked and operated).

[0175] (14) The active power control mode of the negative pole of station D is changed to the constant frequency control mode, the reactive power control mode is the constant AC voltage control mode, the active power control mode of the negative pole is changed to bipolar power control, and the negative pole is reversed connection state (note that the DC starting resistor is in the connected state).

[0176] (15) The high voltage DC switch of the DC negative line of station C is switched to the running state.

[0177] (16) The high voltage DC switch of the DC negative line of station D is switched to the running state. The negative pole of station D is fully charged and unlocked after the conditions for unlocking are met. The AC side incoming line switch of the negative pole converter is switched to the running state.

[0178] (17) The high voltage DC switches on both sides of the AC DC positive line are switched to the operating state (no sequence).

[0179] (18) The high voltage DC switch of the AC DC negative line of station A is switched to the running state.

[0180] (At this time, the active power control mode of the positive and negative poles of station A automatically switches to constant active power control.)

[0181] (19) to (24) are general steps and are the same as those described above.

[0182] The above steps can be extended to multi-terminal flexible DC transmission systems. First, the end-to-end startup between the AC interconnected power station and the renewable energy islanded power station is completed; then, interconnection between multiple interconnected power stations is performed; finally, interconnection between multiple renewable energy islanded power stations is performed. Detailed steps are as follows:

[0183] Initial setup: The positive and negative poles, DC buses, DC lines, and metallic return lines of each converter station are all in cold standby mode (cold standby mode means that the circuit breakers and the isolating switches on both sides of the circuit breakers are in the open state, and the corresponding grounding switches are in the open state). The AC side switches of the converters are in cold standby mode, the AC bus of the new energy island station is in cold standby mode, and the bus tie and sectionalizing switches are closed. The high-voltage DC circuit breakers of the positive and negative DC lines between AC interconnecting stations are not available (cold standby or under maintenance).

[0184] (1) The grounding device of the network with grounding device is switched to the operating state.

[0185] (2) All metal return lines between the connected station and the corresponding new energy island station are switched to the operating state, in order of the nearest to the farthest grounding point.

[0186] (3) Close the DC positive and negative line-4 disconnect switches of each station (there is no order in the operation of the line disconnect switches of each station).

[0187] (4) The DC positive and negative lines of the connected station and the corresponding new energy island station are switched to the operating state (without order).

[0188] (5) Except for special poles, the positive and negative poles of the connected website are converted to constant DC voltage control and constant reactive power control.

[0189] (6) Except for special poles, all other poles of the network are converted to network connections.

[0190] (7) Except for the special pole, all other poles of the connected station are charged by the converter and unlocked.

[0191] (9) Except for special poles, the new energy island station corresponding to the network station shall be unlocked and the AC side circuit breaker of the converter shall be switched to the operating state.

[0192] (10) The metal loop between the interconnected websites is switched to the running state.

[0193] (11) Only one grounding device of the connected station is kept in operation, and the grounding devices of the other connected stations are switched to hot standby.

[0194] (12) Switch the bypass isolating switch corresponding to the special station pole line circuit breaker to the running state.

[0195] (13) The active power control mode of the special station and the special pole is switched to the constant DC voltage control mode, the reactive power control mode is the constant reactive power control mode, the special pole is connected to the network, and the special pole is unlocked and operated after charging.

[0196] (14) The active power control mode of the new energy island station corresponding to the special station is changed to the constant frequency control mode, and the reactive power control mode is the constant AC voltage control mode. The active power control mode of this station is changed to bipolar power control, and this station is connected to the island (note that the DC starting resistor is in the connected state).

[0197] (15) The high-voltage DC circuit breaker of the corresponding pole line of the special station between the special station and the new energy island station is put into operation.

[0198] (16) The high voltage DC circuit breaker of the DC positive line of the new energy island station between the special station and the new energy island station is put into operation. The corresponding pole of the new energy island station is fully charged and unlocked after the unlocking conditions are met. The AC bus side switch of the converter of that pole is put into operation.

[0199] (17) The high-voltage DC circuit breakers on both sides of the DC positive and negative lines of the special station opposite the special pole line are switched to the operating state (without order).

[0200] (18) The special station special pole line to pole line high voltage DC circuit breaker is switched to the operating state.

[0201] (At this time, the active power control mode of the special station automatically switches to constant active power control.)

[0202] (19) The positive and negative active power control mode of the AC connection site is changed to bipolar power control.

[0203] (20) The metal loop between new energy island stations is switched to the operating state (no sequence).

[0204] (21) The high-voltage DC circuit breakers on both sides of the positive and negative DC lines between the new energy island stations are switched to the operating state (without sequence).

[0205] (22) The station service transformer is switched off, and the energy-consuming transformer and energy-consuming device are put into operation.

[0206] (23) Power generation from new energy power plants.

[0207] (24) Notify the automatic power control curve of the website to be put into automatic control.

[0208] Therefore, based on actual cases encountered in the operation of flexible DC projects, this invention clearly defines the start-up and scheduling operation steps for multi-terminal flexible DC transmission projects when the DC line circuit breaker between two AC interconnected stations is unavailable. This operation method can ensure the normal operation of the flexible DC system under such conditions, providing a guarantee for the safety and stability of the power grid.

[0209] Exemplary device

[0210] Figure 7 This is a schematic diagram of the starting device for when the multi-terminal flexible DC grid interconnection inter-station pole line circuit breaker is disabled, provided in an exemplary embodiment of the present invention. Figure 7 As shown, the device 700 includes:

[0211] The first startup module 710 is used to sequentially switch the grounding devices of each interconnected station of the multi-terminal flexible DC grid, the metal return lines of the interconnected station and the corresponding new energy island station, the pole line-4 disconnect switch, the positive and negative pole lines of the interconnected station and the corresponding new energy island station, and the positive and negative poles of the interconnected station except for the special poles, to the operating state, and sequentially start the positive and negative pole converters of each interconnected station and the corresponding new energy island station, and switch the metal return lines between interconnected stations to the operating state and shut down the redundant in-station grounding devices, thus completing the end-to-end startup of multiple interconnected stations and their corresponding new energy island stations except for the special poles;

[0212] The second startup module 720 is used to start the converter in the order of special pole of special interconnection site and corresponding pole of new energy island station corresponding to special interconnection site, and connect the pole lines of the two ends of the flexible DC grid except for the special pole of special interconnection site, to complete the end-to-end startup of special interconnection site and corresponding new energy island station special pole;

[0213] Module 730 is completed to adjust the power control mode of the interconnected power station to bipolar power control, connect the metal return lines and positive and negative lines between the new energy islanded stations, and connect the new energy islanded stations to the new energy power plants for power supply, thus completing the connection of the pole lines between multiple new energy islanded stations and the power supply to the new energy power plants.

[0214] Optionally, the first startup module 710 includes:

[0215] The first conversion submodule is used to convert the metal return lines between the interconnecting stations of the multi-terminal flexible DC grid and the corresponding new energy island stations into the operating state according to the order of the grounding points from near to far.

[0216] The second conversion submodule is used to close the DC positive and negative lines of each connected station and the new energy island station, and switch the DC positive and negative lines of the connected station and the corresponding new energy island station to the operating state.

[0217] The third conversion submodule is used to convert the positive and negative terminals of the interconnected network, except for special terminals, into constant DC voltage control and constant reactive power control.

[0218] The connection submodule is used to convert all poles of the network site, except for special poles, into network connections;

[0219] The charging submodule is used to charge and unlock all terminals of the interconnected network except for special terminals;

[0220] The fourth conversion submodule is used to unlock all poles of the new energy island station corresponding to the connected site, except for special poles, and to switch the AC side circuit breaker of the converter to the operating state.

[0221] The fifth conversion submodule is used to convert the inter-site metal loopback to the running state;

[0222] The first startup submodule is used to keep only one interconnected station grounding device running, while the grounding devices of the remaining interconnected stations are switched to hot standby, completing the end-to-end startup of multiple interconnected stations and their corresponding new energy island stations except for special poles.

[0223] Optionally, the second startup module 720 includes:

[0224] The sixth conversion submodule is used to switch the bypass isolating switch corresponding to the special interconnection pole line circuit breaker of the multi-terminal flexible DC grid to the operating state;

[0225] The running submodule is used to switch the special connected pole to constant DC voltage control mode and constant reactive power control mode, and to connect the special pole to the network. The special connected pole is unlocked and run after charging.

[0226] The seventh conversion submodule is used to convert the corresponding pole of the new energy island station corresponding to the special connection station to a constant frequency and constant AC voltage control mode, and convert the pole to an island connection state;

[0227] The eighth conversion submodule is used to switch the corresponding pole DC circuit breaker of the special connection site between the special connection site and the corresponding new energy island station to the operating state;

[0228] The ninth conversion submodule is used to switch the island station positive line circuit breaker between the special interconnection site and the corresponding new energy island station to the operating state, and unlock and operate it after the unlocking conditions are met, and switch the AC bus side switch of the pole converter to the operating state.

[0229] The tenth conversion submodule is used to switch the circuit breakers on both sides of the DC positive and negative lines of the station opposite the faulty pole line of the faulty connection site to the operating state;

[0230] The second startup submodule is used to finally switch the special interconnected station pole-to-pole circuit breaker to the operating state, completing the startup of the special interconnected station and the corresponding new energy island station at the special extreme end.

[0231] Optionally, module 730 is completed, including:

[0232] The eleventh conversion submodule is used to convert the positive and negative active power control mode of the AC interconnection site of the multi-terminal flexible DC grid into bipolar power control.

[0233] The twelfth conversion submodule is used to convert the inter-station metal loop of the new energy island to the running state;

[0234] The thirteenth conversion submodule is used to switch the high-voltage DC circuit breakers on both sides of the DC positive and negative lines between the new energy island stations to the operating state;

[0235] The electronic module is used to connect the isolated new energy power station to the new energy power plant for power generation.

[0236] Complete the submodule, which is used to finally notify the AC connection site to put the automatic power control curve into automatic control, and complete the pole line connection between multiple new energy island stations and the power supply of new energy power plants.

[0237] Exemplary electronic devices

[0238] Figure 8 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. For example... Figure 8 As shown, the electronic device 80 includes one or more processors 81 and memory 82.

[0239] The processor 81 may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0240] The memory 82 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 81 may execute the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above, and / or other desired functions. In one example, the electronic device may further include an input device 83 and an output device 84, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0241] In addition, the input device 83 may also include, for example, a keyboard, a mouse, etc.

[0242] The output device 84 can output various information to the outside. The output device 84 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0243] Of course, for the sake of simplicity, Figure 8 Only some of the components of this electronic device relevant to the present invention are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0244] Exemplary computer program products and computer-readable storage media

[0245] In addition to the methods and apparatus described above, embodiments of the present invention may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0246] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of the present invention. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0247] Furthermore, embodiments of the present invention may also be computer-readable storage media storing computer program instructions thereon, which, when executed by a processor, cause the processor to perform the steps of the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0248] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0249] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0250] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0251] The block diagrams of devices, systems, devices, and systems involved in this invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, systems, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0252] The methods and systems of the present invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of the present invention are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, the present invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers recording media storing programs for performing the methods according to the present invention.

[0253] It should also be noted that in the systems, apparatus, and methods of the present invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalents of the present invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0254] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A starting method for a multi-terminal flexible DC grid interconnection inter-station pole line circuit breaker when disabled, characterized in that, include: The grounding devices of each interconnected power station, the metal return lines between the interconnected power station and the corresponding new energy islanded station, the pole-4 disconnect switch, the positive and negative pole lines between the interconnected power station and the corresponding new energy islanded station, and the positive and negative poles of the interconnected power station (excluding special poles) are sequentially switched to the operating state. The positive and negative pole converters of each interconnected power station and their corresponding new energy islanded station are then started sequentially. The metal return lines between the interconnected power stations are switched to the operating state, and excess in-station grounding devices are shut down. This completes the end-to-end startup of multiple interconnected power stations and their corresponding new energy islanded stations (excluding special poles), including: According to the order of grounding points from near to far, the metal return lines between the interconnected network and the corresponding new energy island station are switched to the operating state; Then close the DC positive and negative line switches of each of the interconnecting stations and the new energy island station to switch the DC positive and negative lines of the interconnecting stations and the corresponding new energy island stations to the operating state. Then, except for the special poles, the positive and negative poles of the interconnected network are converted to constant DC voltage control and constant reactive power control; Then, all poles of the aforementioned network site, except for the special poles, are converted into network connections; Then, all terminals of the interconnecting network except for the special terminal are charged by the converter and unlocked; Then, except for the special pole, the other poles of the new energy island station corresponding to the connected station are unlocked and the AC side circuit breaker of the converter is switched to the operating state; Then the inter-site metal loopback is switched to running status; Finally, only one of the aforementioned interconnected station grounding devices is kept in operation, while the grounding devices of the remaining interconnected stations are switched to hot standby, thus completing the end-to-end startup of multiple interconnected stations and their corresponding new energy island stations except for special poles. After multiple interconnected power stations and their corresponding isolated renewable energy stations are started end-to-end (excluding special poles), the converters are started in the order of special poles of the special interconnected power stations and the corresponding poles of the renewable energy isolated stations corresponding to the special interconnected power stations. The pole lines at both ends of the flexible DC grid, excluding the special poles of the special interconnected power stations, are connected to complete the end-to-end start-up of the special interconnected power stations and their corresponding isolated renewable energy isolated stations. This includes: Switch the bypass isolating switch corresponding to the special interconnection pole line circuit breaker of the multi-terminal flexible DC power grid to the operating state; Then, the special interconnecting electrode is switched to constant DC voltage control mode and constant reactive power control mode, and the special electrode is connected to the network. After the special interconnecting electrode is charged, it is unlocked and put into operation. Then, the corresponding pole of the new energy island station corresponding to the special connection site is switched to a fixed frequency and fixed AC voltage control mode, and the pole is switched to an island connection state; Then, the DC circuit breaker of the corresponding pole of the special interconnection station between the special interconnection station and the corresponding new energy island station is switched to the operating state; Then, the circuit breaker of the positive line of the island station between the special interconnection station and the corresponding new energy island station is switched to the operating state, and is unlocked and operated after the unlocking conditions are met, and the AC bus side switch of the pole converter is switched to the operating state. Then switch the circuit breakers on both sides of the DC positive and negative lines of the station opposite the faulty pole line of the faulty connection site to the operating state; Finally, the special interconnected station pole-to-pole circuit breaker is switched to the operating state to complete the startup of the special interconnected station and the corresponding special extreme end of the new energy island station. After the special interconnecting station and the corresponding special extreme end of the new energy island station are started, the power control mode of the interconnecting station is adjusted to bipolar power control, the metal return line and positive and negative lines between the new energy island stations are connected, and the new energy island stations are connected to the new energy power plants for power supply, thus completing the connection of the pole lines between multiple new energy island stations and the power supply of the new energy power plants.

2. The method according to claim 1, characterized in that, Finally, the power control mode of the interconnected power station is adjusted to bipolar power control. The metal return lines and positive and negative lines between the new energy islanded stations are connected, and the new energy islanded stations are connected to the new energy power plants for power supply. This completes the connection of the pole lines between multiple new energy islanded stations and the power supply to the new energy power plants, including: The active power control mode of the AC interconnection site of the multi-terminal flexible DC grid is converted to bipolar power control. Then, the metal loop between the new energy island stations is switched to operating status; Then, the high-voltage DC circuit breakers on both sides of the positive and negative DC lines between the new energy island stations are switched to the operating state; Then, the aforementioned isolated new energy power station is connected to a new energy power plant for power generation; The notification activates the automatic power control curve of the AC interconnection site, completing the inter-polar line connection between multiple new energy island stations and the power supply of the new energy power station.

3. A starting device for when the inter-station pole line circuit breaker of a multi-terminal flexible DC grid is disabled, used to implement the method described in claim 1, characterized in that, include: The first startup module is used to sequentially switch the grounding devices of each interconnected station of the multi-terminal flexible DC grid, the metal return lines of the interconnected station and the corresponding new energy island station, the pole line-4 disconnect switch, the positive and negative pole lines of the interconnected station and the corresponding new energy island station, and the positive and negative poles of the interconnected station except for the special poles, to the operating state, and to sequentially start the positive and negative pole converters of each interconnected station and the corresponding new energy island station, and to switch the metal return lines between the interconnected stations to the operating state and shut down the redundant in-station grounding devices, thereby completing the end-to-end startup of multiple interconnected stations and their corresponding new energy island stations except for the special poles; The second startup module is used to start the converter in the order of special pole of special interconnection site and corresponding pole of the new energy island station corresponding to the special interconnection site, and connect the pole lines of the two ends of the flexible DC grid except for the special pole of special interconnection site, so as to complete the end-to-end startup of the special interconnection site and the corresponding special pole of the new energy island station. The module is used to adjust the power control mode of the interconnected power station to bipolar power control, connect the metal return lines and positive and negative lines between the new energy islanded stations, and connect the new energy islanded stations to the new energy power plants for power supply, thus completing the connection of the pole lines between multiple new energy islanded stations and the power supply to the new energy power plants.

4. The apparatus according to claim 3, characterized in that, Complete the module, including: The eleventh conversion submodule is used to convert the positive and negative active power control mode of the AC interconnection site of the multi-terminal flexible DC grid into bipolar power control. The twelfth conversion submodule is used to convert the inter-station metal loop of the new energy island to the operating state; The thirteenth conversion submodule is used to switch the high-voltage DC circuit breakers on both sides of the DC positive and negative lines of the new energy island station to the operating state; The electronic module is used to connect the isolated new energy station to the new energy power station for power generation. The completed submodule is used to finally notify the AC interconnection site to put the automatic power control curve into automatic control, complete the pole line connection between multiple new energy island stations and the power supply of the new energy power station.

5. A computer-readable storage medium, characterized in that, The storage medium stores a computer program for performing the method described in any one of claims 1-2.

6. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1-2.

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