A method for over-rated power supply based on a flexible straight back-to-back AC field

Abstract

The application discloses a kind of over-rating power supply methods based on soft straight back-to-back alternating field, it is applied to soft straight back-to-back alternating field topology, method includes: when any area exists over-rating power operation, generate over-supply instruction;According to the over-supply instruction, determine to be powered area, the original conversion unit of to be powered area, target support conversion unit;Obtain the target capacity of the to be powered area and the rated capacity of the target support conversion unit;According to the target capacity and the rated capacity, adjust the connection state of the original conversion unit and the to be powered area;The connection path of the target support conversion unit and the to be powered area is constructed.The application solves the technical problem that existing technology when area appears over-rating power operation demand, the existing soft straight back-to-back alternating field topology is difficult to provide over-rating power support in time and effectively.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission technology, and in particular to a method for supplying power exceeding rated power based on a flexible DC back-to-back AC field. Background Technology

[0002] In recent years, urban electricity load has continued to climb, and the demand for power supply from the power grid has steadily increased. At present, urban power grids generally face prominent problems such as a shortage of transmission channel resources, insufficient local power supply capacity, excessive short-circuit current at key nodes, and insufficient reactive power support capacity in core areas. Therefore, there is an urgent need for power grid capacity expansion, upgrading, and structural optimization.

[0003] Flexible DC transmission technology-enabled multi-terminal flexible DC back-to-back solutions are an important technical approach to mitigate power supply security risks in urban power grids and improve grid operational stability. However, existing flexible DC back-to-back AC power plants generally adopt a single busbar and single converter unit topology, primarily used to provide steady-state power support for corresponding power supply areas. This structure has a relatively singular operating mode; when the load in a region surges and generates power supply demands exceeding the rated power, the existing topology cannot achieve cross-unit power exchange, making it difficult to quickly output excess power support, resulting in significant deficiencies in power supply margin and dynamic adjustment capabilities. Summary of the Invention

[0004] This invention provides a method for supplying power beyond rated power based on a flexible DC back-to-back AC field, in order to solve the technical problem that existing flexible DC back-to-back AC field topologies cannot provide timely and effective support for power exceeding rated power when there is a demand for power exceeding rated power in a region.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a method for supplying over-rated power based on a flexible DC back-to-back AC field topology, applicable to a flexible DC back-to-back AC field topology, comprising: When any area is operating at above-rated power, an over-power supply command is generated. Based on the excess power supply instruction, the area to be powered, the original converter unit of the area to be powered, and the target support converter unit are determined; Obtain the target capacity of the area to be powered and the rated capacity of the target supporting converter unit; Adjust the connection status between the original converter unit and the area to be powered based on the target capacity and the rated capacity; Establish a connection path between the target supporting converter unit and the area to be powered.

[0006] As a preferred embodiment, adjusting the connection state between the original converter unit and the area to be powered, based on the target capacity and the rated capacity, specifically includes: If the rated capacity is not less than the target capacity, then disconnect the original converter unit from the area to be powered. When the rated capacity is less than the target capacity, the connection between the original converter unit and the area to be powered is maintained.

[0007] As a preferred embodiment, constructing the connection path between the target supporting converter unit and the area to be powered specifically includes: Determine whether a bus tie switch assembly exists on the power transmission channel between the target supporting converter unit and the power receiving area; If not, establish a connection path between the target support converter unit and the power supply bus of the area to be powered. If so, determine the transmission bus of the target supporting converter unit, and establish a connection path between the target supporting converter unit, the transmission bus, the bus tie switch assembly, and the power supply bus.

[0008] As a preferred embodiment, the flexible back-to-back AC field topology includes at least two sets of dual buses; Each group of dual busbars includes two busbars; each busbar is connected to a section via a first switching unit; each busbar is connected to a converter unit via a second switching unit; the DC sides of each converter unit are interconnected; each group of dual busbars is cascaded via a bus tie switch assembly; wherein, one end of the two busbars of the first dual busbar is interconnected via a switching device; the other end of the two busbars of the last dual busbar is interconnected via the switching device.

[0009] As a preferred embodiment, the first switching unit includes a first outgoing switch, a first disconnect switch, and a second disconnect switch; One end of the first outgoing switch is connected to the area; The other end of the first outgoing switch is connected to the first disconnect switch and the second disconnect switch, respectively; The first disconnector is connected to one of the two busbars; The second disconnector is connected to the other busbar in the dual busbar system.

[0010] As a preferred embodiment, the second switching unit includes a second outgoing switch, a third disconnect switch, and a fourth disconnect switch; One end of the second outgoing switch is connected to the converter unit; The other end of the second outgoing switch is connected to the third disconnect switch and the fourth disconnect switch respectively; The third disconnector is connected to one of the two busbars; The fourth disconnector is connected to the other busbar in the dual busbar system.

[0011] As a preferred embodiment, the bus tie switch assembly includes two bus tie switch devices; The aforementioned bus tie switch device is respectively connected to one bus in a double busbar and one bus in another double busbar; Another bus tie switch device is connected to the other bus in one of the double busbars and the other bus in the other double busbar.

[0012] As a preferred option, the method also includes: The outgoing switch that is directly connected to the area to be powered is designated as the first target outgoing switch; The outgoing switch that is directly connected to the power receiving area of ​​the target support converter unit under normal operating conditions shall be used as the first target outgoing switch; The switching device connecting the power supply bus and the target bus is designated as the first target switching device; the bus that is connected to the target support converter unit under normal operating conditions is designated as the target bus. The disconnect switch connected to the original converter unit and the target bus, and the disconnect switch connected to the target support converter unit and the power supply bus, are used as the first disconnect switch assembly; The disconnect switch connected to the original converter unit and the power supply bus, and the disconnect switch connected to the target support converter unit and the power supply bus, are used as the second disconnect switch assembly.

[0013] As a preferred embodiment, establishing a connection path between the target supporting converter unit and the power supply bus of the area to be powered specifically includes: Shut down the target supporting converter unit and the original converter unit; Disconnect the first target outgoing line switch and the second target outgoing line switch; The first target switching device for closing the circuit; Close the first disconnect switch assembly and disconnect the second disconnect switch assembly; Disconnect the first target switching device; Close the first target output switch and the second target output switch; Start the target supporting converter unit and the original converter unit.

[0014] As a preferred embodiment, the step of determining the transmission bus of the target supporting converter unit and establishing a connection path between the target supporting converter unit, the target bus, the bus tie switch, and the power supply bus specifically further includes: When the target busbar and the power supply busbar are not directly connected by the bus tie switch device, the power transmission busbar is regarded as a non-target busbar, and the non-target busbar and the target busbar are in the same group of double busbars; Shutting down the target support converter unit and the non-target support converter unit; wherein, the non-target support converter unit is the converter unit that provides energy to the non-target bus under normal operating conditions; Disconnect the second target outgoing switch and the third target outgoing switch; wherein, the third target outgoing switch is an outgoing switch connected between the non-target bus and the power receiving area of ​​the non-target bus; Close the third target switching device, disconnect the third disconnector assembly, close the first target disconnector; and disconnect the fourth disconnector assembly and close the fifth disconnector assembly. Disconnect the third target switching device; Close the bus tie switch device connected between the non-target bus and the power supply bus, and close the third target outgoing switch; Start the target support converter unit and the non-target support converter unit; The third disconnector assembly includes a disconnector connected between the third target outgoing switch and the non-target bus, and a disconnector connected between the non-target bus and the non-target support converter unit; the first target disconnector is a disconnector connected between the non-target bus and the target support converter unit; the third target switching device is a switching device located at the end of the target bus and the non-target bus away from the power supply bus, and is used to connect the target bus and the non-target bus; the fourth disconnector assembly includes a disconnector connected between the second target outgoing switch and the target bus, and a disconnector connected between the target bus and the target support converter unit; the fifth disconnector assembly includes a disconnector connected between the third target outgoing switch and the target bus, and a disconnector connected between the target bus and the non-target support converter unit.

[0015] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The present invention provides a method for supplying over-rated power based on a flexible DC back-to-back AC field topology. Applied to a flexible DC back-to-back AC field topology, it generates and responds to over-rated power supply commands. Based on these commands, it determines the area to be powered, the original converter unit of the area, and the target supporting converter unit, providing a technical basis for providing over-rated power support. Furthermore, by acquiring the target capacity of the area to be powered and the rated capacity of the target supporting converter unit, it adjusts the connection state between the original converter unit and the area to be powered, achieving a preliminary adjustment of the power supply source for the area requiring over-rated power support. Finally, by establishing a connection path between the target supporting converter unit and the area to be powered, it completes the support for the over-rated power operation of the area, thereby solving the technical problem that existing flexible DC back-to-back AC field topologies cannot provide timely over-rated power support when an area requires over-rated power operation.

[0016] Furthermore, in the flexible DC back-to-back AC field topology of this embodiment, each bus is connected to a section through a first switching unit, thereby allowing for flexible switching of the bus connected to the section in practical applications, improving the flexibility of the topology. Additionally, each bus is connected to a converter unit through a second switching unit, allowing for flexible switching of the bus connected to the converter unit in practical applications. Therefore, in this invention, based on the first and second switching units, various connection combinations can be formed between each converter unit, each bus, and each section, thereby constituting multiple power transmission channels and further improving the flexibility of the topology. Furthermore, in this invention, the groups of dual buses are cascaded through the bus tie switch assembly. In this system, one end of each of the two buses at the head of the double busbar is interconnected via the switching device; the other end of each of the two buses at the tail of the double busbar is interconnected via the switching device. This allows the double buses in the topology to be flexibly cascaded with other double buses, further enhancing the flexibility of the topology and creating more power transmission channel combinations. Therefore, in actual operation, when the area requires operation beyond the rated power, the corresponding power transmission channel is activated by switching the states of the bus tie switch assembly, the first switching unit, the second switching unit, and the switching device, providing timely power support to the area. This solves the technical problem that the existing flexible DC back-to-back AC field topology cannot provide timely support beyond the rated power when the area requires operation beyond the rated power. Attached Figure Description

[0017] Figure 1 : This is a schematic diagram of a four-terminal flexible straight back-to-back AC field structure using a single-end single-bus connection method in the prior art; Figure 2 : A schematic diagram of a flexible, straight back-to-back AC field topology provided in an embodiment of the present invention; Figure 3 : A schematic diagram of the structure of a four-terminal flexible straight back-to-back AC field topology provided in an embodiment of the present invention. Figure 4 : A flowchart illustrating the steps of a method for supplying over-rated power based on a flexible back-to-back AC field according to an embodiment of the present invention; Figure 5 : A flowchart of the steps of a method for supplying over-rated power based on a flexible back-to-back AC field according to another embodiment of the present invention; Figure 6 : A schematic diagram of a four-terminal flexible DC back-to-back AC field topology with over-rated power requirements provided in an embodiment of the present invention; Figure 7 The above-rated power supply method based on flexible DC back-to-back AC field provided in this embodiment of the invention is applied to... Figure 6The principle of topological time Figure 1 ;in, Figure 7 (a) shows the topology state when the target support converter unit is unit one; Figure 7 (b) shows the state of the topology after performing steps S21 and S22. Figure 7 (c) shows the state of the topology after performing steps S23 and S24. Figure 7 (d) shows the state of the topology after executing steps S25 to S27; Figure 8 The above-rated power supply method based on flexible DC back-to-back AC field provided in this embodiment of the invention is applied to... Figure 5 The principle of topological time Figure 2 ;in, Figure 8 (a) shows the topology when the target support converter unit is a four-cell topology. Figure 8 (b) shows the state of the topology after performing steps S32 and S33. Figure 8 (c) shows the state of the topology after executing step S34. Figure 8 (d) shows the state of the topology after executing steps S35 to S36; Figure 8 (e) shows the state of the topology after step S37 is executed. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Currently, there are few multi-terminal flexible DC back-to-back projects in operation. To meet the non-loop operation requirements under normal AC outgoing line conditions, DC converters need to be connected to different areas to achieve DC isolation and interconnection. The current AC field wiring method for flexible DC back-to-back systems is a single busbar, single converter unit connection, with no electrical connection between the individual buses. Under normal operating conditions, the existing single-terminal, single-busbar flexible DC back-to-back AC field provides power support to a fixed receiving area through a single converter unit. However, in actual operation, the grid load is uneven, and there may be situations where the load in the core receiving area exceeds the rated capacity of the converter unit. In such cases, the converter units in the existing topology cannot provide effective power support to the core receiving area.

[0020] Taking the existing four-terminal flexible straight back-to-back AC field as an example, such as Figure 1As shown, the AC field uses a single-end, single-busbar wiring configuration. Rectangles represent outgoing switches, smaller circles connected to these switches are disconnectors, two overlapping circles represent flexible DC converter transformers, and #2M, #1M, #5M, and #6M represent individual buses. This flexible DC back-to-back AC field contains four converters, VSC1 to VSC4. Each converter is connected to a busbar via a flexible DC converter transformer, outgoing switch, and disconnector, and transmits power to a specific receiving area via the busbar. In this topology, when an area requires additional power support due to temporary over-rated power operation, current technology struggles to provide timely support due to limitations in the rated capacity of the converter units and the existing topology structure.

[0021] Example 1 This invention provides a method for supplying over-rated power based on a flexible DC back-to-back AC field topology, applicable to flexible DC back-to-back AC field topology, such as... Figure 2 As shown. The flexible DC AC field topology may include: at least two sets of double busbars 1; each set of double busbars 1 includes two buses; each busbar is connected to the area through a first switching unit 2; each busbar is connected to the converter unit 4 through a second switching unit 3; the DC sides of each converter unit 4 are interconnected; each set of double busbars 1 is cascaded through a bus tie switch assembly; wherein, one end of the two buses of the first double busbar 1 is interconnected through a switching device 5; the other end of the two buses of the last double busbar 1 is interconnected through a switching device 5.

[0022] It should be noted that the first switching unit 2 is equipped with an outgoing switch and a disconnector, which have both on and off states. In practical applications, by switching the states of the various devices inside the first switching unit 2, the connection relationship between the two buses in the double busbar 1 and the area is adjusted. The second switching unit 3 works similarly to the first switching unit 2. In practical applications, by switching the states of the switching devices inside the second switching unit 3, the connection relationship between the two buses in the double busbar 1 and the converter unit 4 is adjusted. The number of groups in the double busbar 1 can be determined according to the actual situation.

[0023] In this embodiment, each first switching unit 2 is connected to one area, and each second switching unit 3 is connected to one converter unit 4. In a set of dual buses 1, one bus can connect two first switching units 2 and connect to two areas respectively through the two first switching units 2, and one bus can connect two second switching units 3 and connect to two converter units 4 respectively through the two second switching units 3.

[0024] The converter unit 4 includes a converter and a converter transformer. The converter and the converter transformer are connected, and the converter transformer is connected to the second switching unit 3. In this embodiment, the DC sides of each converter are interconnected.

[0025] In this embodiment, the switching device 5 connecting the two busbars can be a bus tie switch, which has on and off states. The bus tie switch assembly 6 is internally equipped with a bus tie switch for connecting and disconnecting the connection between the two busbars.

[0026] Specifically, each double busbar 1 is cascaded with each bus tie switch device in the bus tie switch assembly 6. Therefore, one end of the two buses of one set of double busbar 1 is connected to one end of the two buses of another set of double busbars through the bus tie switch assembly 6, and the other end of this other set of double busbar 1 is connected to one end of the two buses of the next set of double busbar 1 through the bus tie switch assembly 6, and so on, forming a chain connection structure, so that the topology as a whole constitutes a multi-terminal flexible DC back-to-back AC field.

[0027] In this chain connection structure, one end of each of the two busbars of the first double busbar 1 is interconnected via a switching device 5. The other end of each of the two busbars of the last double busbar 1 is interconnected via a switching device 5.

[0028] Therefore, in the topology of this embodiment, each busbar is connected to a region via a first switching unit 2. This allows for flexible switching of the busbar connected to the region via the first switching unit 2, improving the flexibility of the topology. Furthermore, each busbar is connected to a converter unit 4 via a second switching unit 3. This allows for flexible switching of the busbar connected to the converter unit 4 via the second switching unit 3. Thus, in this invention, based on the first switching unit 2 and the second switching unit 3, various connection combinations can be formed between each converter unit 4, each busbar, and each region, thereby constituting multiple power supply channel combinations and further enhancing the flexibility of the topology. The invention provides an active system; furthermore, in this invention, each double busbar 1 is cascaded via a bus tie switch assembly 6; wherein, one end of the two buses of the first double busbar 1 is interconnected via a switch device 5; the other end of the two buses of the last double busbar 1 is interconnected via a switch device, allowing the topology to form more combinations of power transmission channels. Thus, when the area experiences an over-rated power operation demand, the states of the bus tie switch assembly 6, the first switching unit 2, the second switching unit 3, and the switch device 5 are switched to conduct the corresponding power transmission channels, providing over-rated power support to the area. This solves the technical problem that existing flexible DC back-to-back AC field topologies cannot provide timely over-rated power support.

[0029] In one embodiment, the first switching unit includes a first outgoing switch, a first disconnect switch, and a second disconnect switch; One end of the first outgoing switch is connected to the area; The other end of the first outgoing switch is connected to the first disconnect switch and the second disconnect switch respectively; The first disconnector is connected to one of the two busbars; The second disconnector is connected to the other busbar in the double busbar system.

[0030] It should be noted that in practical applications, the power supply to the area is maintained or stopped by switching the on / off state of the first outgoing switch. The busbar supplying power to the area is switched by switching the on / off state of the first disconnect switch and the second disconnect switch. For example, when the first disconnect switch is open and the second disconnect switch is closed, the other busbar in the dual busbar system supplies power to the area; when the second disconnect switch is open and the first disconnect switch is closed, only one busbar in the dual busbar system supplies power to the area.

[0031] In one embodiment, the second switching unit includes a second outgoing switch, a third disconnect switch, and a fourth disconnect switch; One end of the second outgoing switch is connected to the converter unit; The other end of the second outgoing switch is connected to the third and fourth disconnect switches respectively; The third disconnector is connected to one of the two busbars; The fourth disconnect switch is connected to the other busbar in the double busbar system.

[0032] It should be noted that in practical applications, the connection to the converter unit is established or terminated by switching the on / off state of the second outgoing switch. Furthermore, the connection to the converter unit is switched by switching the on / off states of the third and fourth disconnect switches, thus altering the power supply path of the converter unit. For example, when the third disconnect switch is open and the fourth disconnect switch is closed, the converter unit connects to the other bus in the dual busbar system, providing energy to that other busbar and supplying power to the area through it. When the fourth disconnect switch is open and the third disconnect switch is closed, the converter unit connects to one of the dual busbar systems, providing energy to that busbar and supplying power to the area through it.

[0033] In one embodiment, the bus tie switch assembly includes two bus tie switch devices; A bus tie switch is connected to one bus in a double busbar system and one bus in another double busbar system. Another bus tie switch is connected to the other bus in one double bus and the other bus in another double bus.

[0034] It should be noted that in each set of double busbars, the two busbars are connected to two bus tie switches, and through the two bus tie switches, they are connected to the next set of double busbars. The two busbars of the next set of double busbars are also connected to two bus tie switches, and through the two bus tie switches, they are connected to the next set of double busbars, and so on, forming a chain structure. Each busbar is connected to the first switching unit and the second switching unit, and through each first switching unit, it is connected to the corresponding area, and through each second switching unit, it is connected to the corresponding converter unit, thus forming a multi-terminal flexible DC back-to-back AC field structure.

[0035] Among them, one end of the two busbars at the beginning (i.e., the end not connected to the bus tie switch device) is connected to each other through a switch device, while the other end of the two busbars at the end (i.e., the end not connected to the bus tie switch device) is connected to each other through a switch device.

[0036] In one application example, a four-terminal flexible DC back-to-back AC field constructed based on the wiring principle of the topology provided in this embodiment is used as an example to illustrate the above topology. For example... Figure 5 As shown, units one through four represent the converter units. VSC1 through VSC4 represent the converters, with one end of each converter connected to its corresponding converter transformer, and the other ends of each converter interconnected. In the first switching unit 2 and the second switching unit 3, rectangles represent outgoing line switches, circles represent disconnectors, shaded areas represent on, and unshaded areas represent off. Figure 5 This shows the on / off status of each outgoing switch, each disconnector, each bus tie switch, and each switching device under normal operating conditions.

[0037] Specifically, Figure 5 In this configuration, two buses, #1M and #2M, located at the first end of the double busbar, are interconnected at one end via switching device 5, and their other ends are respectively connected to the bus tie switch device in the bus tie switch assembly 6. These buses are then connected to one end of buses #5M and #6M in another double busbar configuration via the bus tie switch device in the bus tie switch assembly 6. The other ends of buses #5M and #6M are interconnected via switching device 5. Each busbar connects to two first switching units 2, which in turn connect to two different zones. Furthermore, each busbar connects to two second switching units 3, which in turn connect to two converter units 4.

[0038] In order from left to right, we can... Figure 5 The two sets of double busbars on the left and right sides are divided into the first set of double busbars and the second set of double busbars. Figure 5Taking the second group of double busbars as an example, in the second group of double busbars, busbar #5M is connected to two first switching units 2 respectively. Busbar #5M is connected to area four through the disconnect switch and outgoing switch in the first switching unit 2 on the left, and to area four through the disconnect switch and outgoing switch in the first switching unit 2 on the right. It is also connected to unit four through the disconnect switch and outgoing switch in the second switching unit 3 on the left, and to unit three through the disconnect switch and outgoing switch in the second switching unit 3 on the right. When operating under normal conditions, in the second switching unit 3 on the right, the outgoing switch and disconnect switch connecting unit three to busbar #5M are in the conducting state, and in the first switching unit 2 on the right, the outgoing switch and disconnect switch connecting busbar #5M to area three are in the conducting state. Therefore, unit three provides energy to busbar #5M, and busbar #5M provides energy to area three.

[0039] Similarly, bus #6M connects to the disconnect switch of the first switching unit 2 on the left, and is connected to area four based on the connection relationship between the disconnect switch and the outgoing switch. Bus #6M also connects to the disconnect switch of the first switching unit 2 on the right, and is connected to area three based on the connection relationship between the disconnect switch and the outgoing switch. Bus #6M connects to the disconnect switch of the second switching unit 3 on the left, and is connected to unit four based on the connection relationship between the disconnect switch and the outgoing switch. Bus #6M also connects to the disconnect switch of the second switching unit 3 on the right, and is connected to unit three based on the connection relationship between the disconnect switch and the outgoing switch. When operating under normal conditions, in the second switching unit 3 on the left, the outgoing switch and disconnect switch connected to unit four and bus #6M are in a conducting state. In the first switching unit 2 on the left, the outgoing switch and disconnect switch connected to area four and bus #6M are in a conducting state. Therefore, unit four provides energy to bus #6M, and bus #6M provides energy to area four. It is understandable that the connection structure of busbar #1M and busbar #2M is the same as that of busbar #5M and busbar #6M, and will not be described again here.

[0040] Therefore, when a section of the AC field topology requires power support exceeding the rated capacity, the on / off states of the bus tie switch assembly, the first switching unit, the second switching unit, and the switching devices can be switched to establish a transmission channel between the providing converter unit and the receiving section, thereby completing the power support exceeding the rated capacity. It is evident that the topology used in this embodiment can be flexibly modified to achieve the effect of flexibly establishing a transmission channel, avoiding the situation where existing flexible DC back-to-back AC field topologies rely on a single converter to power a fixed section, resulting in a fixed and inflexible topology structure. Moreover, compared to existing four-terminal flexible DC back-to-back AC field topologies, this topology only requires the addition of four switches and eight disconnectors, making the structure simple and easy to implement.

[0041] It is understood that the topology provided in this embodiment is not limited to the four-terminal flexible-vertical back-to-back AC field topology. Based on the wiring principle of the topology provided by this invention, a multi-terminal flexible-vertical back-to-back AC field can be constructed according to actual needs.

[0042] Implementing the above embodiments has the following effects: In the flexible DC back-to-back AC field topology proposed in this embodiment, each bus is connected to the power supply area via a first switching unit. This switching unit enables flexible switching of the bus access to the area, effectively improving topology adaptability. Each bus is simultaneously connected to the converter unit via a second switching unit, allowing for flexible network configuration between the converter unit and the bus. Relying on the coordinated operation of the first and second switching units, each converter unit, bus, and power supply area can form multiple topology connection combinations, constructing multiple independent transmission channels and significantly enhancing the system's topology operational flexibility. In this topology, each set of dual buses achieves a cascaded architecture through bus tie switch components. Switching devices are configured at one end of the first dual bus and the other end of the last dual bus to achieve bus interconnection, enabling flexible cascading expansion of multiple sets of dual buses and further enriching the transmission channel combination forms. When the power supply area experiences operation conditions exceeding the rated power, the adapted transmission channel can be quickly put into operation by adjusting the switching status of the bus tie switch assembly, the two-stage switching unit, and the switching devices, so as to deliver redundant power to the load area in real time, effectively solving the technical shortcoming of the existing flexible DC back-to-back topology that cannot provide excess power support in a timely manner.

[0043] Example 2 Please see Figure 4 This invention provides a method for supplying over-rated power based on a flexible DC back-to-back AC field, comprising the following steps: Step 101: When any area is operating at above-rated power, generate an over-power supply command.

[0044] It should be noted that by collecting real-time active and reactive load operation data of each power supply area, the real-time operating power is continuously compared with the preset rated power threshold of the area. Combined with the set judgment delay and fluctuation anti-misjudgment logic, the system identifies the power over-limit conditions of the area, thereby determining whether any area is in an over-rated power operation state. Based on this state, a corresponding over-power supply instruction is generated. The over-power supply instruction can identify and mark the area whose real-time power continuously exceeds the rated threshold as a waiting power receiving area by real-time monitoring of the load power, bus power flow and converter unit operation status of each power supply area. The converter unit connected to the waiting power receiving area is determined as the original converter unit. Then, based on the remaining adjustable capacity, operating margin, electrical connection topology and transmission channel availability of each converter unit, idle converter units with surplus power adjustment capabilities and which can form an effective transmission path through the bus and bus tie switch components are selected as target support converter units. Finally, the corresponding over-power supply instruction is generated.

[0045] Step 102: Based on the over-power supply instruction, determine the area to be powered, the original converter unit of the area to be powered, and the target support converter unit.

[0046] It should be noted that the "waiting power receiving area" refers to an area with the requirement to operate beyond its rated power. The original converter unit of the waiting power receiving area refers to the converter unit that provides energy to the waiting power receiving area under normal operating conditions. The target support converter unit refers to the converter unit that provides power support to the waiting power receiving area under operating conditions beyond its rated power. The over-power supply command includes information used to identify the waiting power receiving area, its original converter unit, and the target support converter unit.

[0047] When an over-power supply command is received, it indicates that there is a region in the topology that needs to be supported with more power than rated. At this time, the over-power supply command is responded to and parsed. Based on the information contained in the over-power supply command, the region to be powered, the original converter unit of the region to be powered, and the target supporting converter unit are determined.

[0048] Step 103: Obtain the target capacity of the area to be powered and the rated capacity of the target supporting converter unit.

[0049] It should be noted that the target capacity of the power receiving area refers to the capacity required when the power receiving area is operating under conditions exceeding the rated power.

[0050] Step 104: Adjust the connection status between the original converter unit and the area to be powered according to the target capacity and rated capacity.

[0051] It should be noted that step 104 adjusts the connection status between the original converter unit and the area to be powered based on the target capacity and the rated capacity of the target supporting converter unit, so as to meet the power demand of the area to be powered while making more reasonable use of the capacity of the original converter unit.

[0052] For example, when the target support converter units are sufficient to meet the needs of the receiving area, the connection between the original converter unit and the receiving area can be disconnected, allowing the original converter unit to be used to supply power to other areas. This achieves both over-rated power support for the receiving area and makes reasonable use of the capacity of the original converter unit, improving the utilization rate of the converter unit capacity. Conversely, when the target support converter units are insufficient to meet the needs of the receiving area, the connection between the receiving area and the original converter unit can be maintained, allowing both the target support converter unit and the original converter unit to jointly provide over-rated power support for the receiving area.

[0053] Step 105: Establish a connection path between the target support converter unit and the area to be powered.

[0054] It should be noted that, in this embodiment, by establishing a connection path between the target support converter unit and the area to be powered, the target support converter unit transmits energy to the area to be powered through the connection path, thereby achieving power support.

[0055] It is understood that in this embodiment, there is no specific order between steps 104 and 105. They can be performed simultaneously, or steps 104 can be performed first and then steps 105, or steps 105 can be performed first and then steps 104.

[0056] This embodiment responds to over-power supply commands and, based on these commands, determines the area to be powered, the original converter unit of the area to be powered, and the target supporting converter unit, providing a technical basis for providing over-rated power support. It also obtains the target capacity of the area to be powered and the rated capacity of the target supporting converter unit, and adjusts the connection status between the original converter unit and the area to be powered based on these values. This achieves an initial adjustment of the power supply source for the area to be powered requiring over-rated power support, thereby improving the utilization rate of the converter unit capacity while meeting the over-rated power demand of the area. Finally, by establishing a connection path between the target supporting converter unit and the area to be powered, it completes the support for the over-rated power operation of the area to be powered. This solves the technical problem that existing flexible DC back-to-back AC field topologies cannot provide timely over-rated power support when an area has over-rated power operation requirements.

[0057] Implementing the above embodiments has the following effects: By generating and responding to over-power supply commands, and determining the receiving area, the original converter unit, and the target support converter unit based on these commands, a technical foundation is provided for providing over-rated power support. Furthermore, by acquiring the target capacity of the receiving area and the rated capacity of the target support converter unit, the connection status between the original converter unit and the receiving area is adjusted, achieving a preliminary adjustment of the power supply source for the receiving area requiring over-rated power support. Finally, by establishing a connection path between the target support converter unit and the receiving area, support for over-rated power operation of the receiving area is completed, thus solving the technical problem that existing flexible DC back-to-back AC field topologies cannot provide timely over-rated power support when an area experiences over-rated power operation requirements.

[0058] Example 3 Please see Figure 5 Another embodiment of the present invention provides a method for supplying power beyond rated capacity based on a flexible DC back-to-back AC field, which may include: Step 201: Respond to the over-power supply command. Based on the over-power supply command, determine the area to be powered, the original converter unit of the area to be powered, and the target support converter unit.

[0059] Step 202: Obtain the target capacity of the area to be powered and the rated capacity of the target supporting converter unit.

[0060] It should be noted that steps 201-202 are the same as steps 101-102, and will not be repeated here.

[0061] Step 203: When the rated capacity is not less than the target capacity, disconnect the original converter unit from the area to be powered; when the rated capacity is less than the target capacity, maintain the connection between the original converter unit and the area to be powered.

[0062] Specifically, determine whether the rated capacity is not less than the target capacity; if so, disconnect the original converter unit from the area to be powered; if not, maintain the connection between the original converter unit and the area to be powered.

[0063] It should be noted that when the rated capacity of the target support converter unit is not less than the target capacity, it means that the target support converter unit itself can provide sufficient capacity for the area to be powered. In this case, the target support converter unit can be used to provide over-rated power support to the area to be powered. Therefore, the connection between the original converter unit and the area to be powered can be disconnected, so that the original converter unit can be used to supply power to other areas. This satisfies the over-rated power demand of the area to be powered while improving the utilization rate of the original converter unit capacity and reducing energy waste.

[0064] When the rated capacity of the target supporting converter unit is less than the target capacity, it means that the capacity of the target supporting converter unit itself is not sufficient to meet the capacity requirements of the area to be powered. It is necessary to combine the original converter unit to supply power to the area to be powered. Therefore, the connection between the original converter unit and the area to be powered should be maintained.

[0065] Understandably, the selection of the target supporting converter unit can be based on the capacity of the original converter unit and the target capacity of the area to be powered, such as when the sum of the rated capacity of the target supporting converter unit and the capacity of the original converter unit is greater than or equal to the target capacity. Therefore, when the target supporting converter unit and the original converter unit jointly supply power to the area to be powered, the demand for over-rated power in the area to be powered can be met.

[0066] Step 204: Determine whether there is a bus tie switch assembly on the power transmission channel between the target support converter unit and the area to be powered; if not, establish a connection path between the power supply bus of the target support converter unit and the area to be powered; if so, determine the power transmission bus of the target support converter unit and establish a connection path between the target support converter unit, the power transmission bus, the bus tie switch assembly and the power supply bus.

[0067] It should be noted that the power supply bus of the area to be powered refers to the bus that provides power transmission to the area to be powered. Under normal operating conditions, the power supply bus is connected to the original converter unit.

[0068] The power transmission channel can provide feedback on the energy flow path. As described in the aforementioned topology, by changing the on / off states of the first switching unit, the second switching unit, and the bus tie switch assembly, the connection relationship between each converter unit and each area can be altered. Based on this, the power transmission channel between the target supporting converter unit and the area to be powered can be determined in the topology. Thus, based on this power transmission channel, it can be determined whether the energy transferred between the target supporting converter unit and the area to be powered needs to pass through the bus tie switch assembly. If not, there is no bus tie switch assembly on the power transmission channel; if so, there is.

[0069] If there is no bus tie switch assembly, it means that the target support converter unit and the original converter unit of the area to be powered are connected in the same double bus. In this case, the bus connected to the target support converter unit and the bus connected to the original converter unit can be interchanged by switching the on / off state of the second switching unit. This changes the bus connected to the target support converter unit and the bus connected to the original converter unit, so that the target support converter unit can provide power support to the area to be powered through the bus connected to the original converter unit.

[0070] When a bus tie switch assembly is present, it indicates that the target support converter unit and the original converter unit are not connected to the same double busbar, and the double busbars connected to the target support converter unit and the original converter unit are connected through the bus tie switch assembly. Since the two buses in the two sets of double busbars are connected one-to-one through the bus tie switch devices in the bus tie switch assembly, in this case, the busbar connected to the target support converter unit and the busbar connected to the original converter unit may not have a direct conductive connection structure. Therefore, it is necessary to determine the transmission busbar of the target support converter unit, and then establish a connection path between the target support converter unit, the transmission busbar, the bus tie switch assembly, and the power supply busbar, so that the target support converter unit can conduct to the area to be powered, thereby enabling the target support converter unit to provide power support to the area to be powered.

[0071] In one embodiment, when there is no bus tie switch assembly on the power transmission channel between the target supporting converter unit and the area to be powered, the establishment of the connection path between the power supply bus of the target supporting converter unit and the area to be powered in step 204 may specifically include: Step S21: Shut down the target support converter unit and the original converter unit.

[0072] It should be noted that this step can be achieved by shutting down the converter in the target supporting converter unit. The original converter unit works similarly.

[0073] This step improves operational safety by shutting down both the target support converter unit and the original converter unit, thus suspending their operation.

[0074] Step S22: Disconnect the first target outgoing line switch and the second target outgoing line switch.

[0075] Among them, the first target outgoing switch refers to the outgoing switch that is directly connected to the power receiving area, and the second target outgoing switch is the outgoing switch that is directly connected to the power receiving area of ​​the target support converter unit under normal operating conditions.

[0076] It should be noted that the power receiving area of ​​the target support converter unit refers to the area that receives power from the target support converter unit under normal operating conditions.

[0077] It is understandable that steps S21 and S22 can be performed simultaneously.

[0078] Step S23: Close the first target switching device.

[0079] The first target switching device refers to the switching device connecting the power supply bus and the target bus. The target bus refers to the bus that is normally connected to the target support converter unit. It should be noted that the power supply bus and the target bus are in the same double bus. As can be seen from the above topology, one end of the same double bus is connected to each other through a switching device. Therefore, the switching device that connects one end of the power supply bus and one end of the target bus is the first target switching device.

[0080] This step connects the power supply bus and the target bus by closing the first target switching device.

[0081] Step S24: Close the first disconnector assembly and disconnect the second disconnector assembly.

[0082] The first disconnector assembly includes a disconnector connected to the original converter unit and the target bus, and a disconnector connected to the target support converter unit and the power supply bus; the second disconnector assembly includes a disconnector connected to the original converter unit and the power supply bus, and a disconnector connected to the target support converter unit and the power supply bus.

[0083] It should be noted that in the topology, the original converter unit is connected to the power supply bus and the target bus respectively through different disconnect switches, and the target support converter unit is connected to the power supply bus and the target bus respectively through different disconnect switches.

[0084] Under normal operating conditions, the disconnect switch connecting the primary converter unit and the power supply bus is closed, while the disconnect switch connecting the primary converter unit and the target bus is open, allowing the primary converter unit to supply power to the power supply bus and then to the receiving area via the power supply bus. Under normal operating conditions, the disconnect switch connecting the target support converter unit and the target bus is closed, while the disconnect switch connecting the target support converter unit and the power supply bus is open, allowing the target support converter unit to supply power to the target bus and then to the receiving area via the target bus.

[0085] In this step, the disconnect switch between the original converter unit and the target bus is closed, and the disconnect switch between the original converter unit and the power supply bus is opened, thereby switching the connection object of the original converter unit from the power supply bus to the target bus, changing the power supply path and power supply object of the original converter unit, so that the original converter unit can transmit power to the power receiving area of ​​the target supporting converter unit through the target bus.

[0086] Furthermore, this step closes the disconnect switch between the target support converter unit and the power supply bus, and disconnects the disconnect switch between the target support converter unit and the target bus, thereby switching the connection object of the target support converter unit from the target bus to the power supply bus, changing the power supply path and power supply object of the target support converter unit, so that the target support converter unit can transmit power to the area to be powered through the power supply bus.

[0087] Based on the above, this step realizes the interchange of the receiving areas of the original converter unit and the target support converter unit, enabling the target support converter unit to supply power to the receiving area, and enabling the original converter unit to supply power to the receiving area of ​​the target support converter unit. This improves the utilization rate of the original converter unit's capacity and reduces energy waste while meeting the overrated power demand of the receiving area.

[0088] Step S25: Disconnect the first target switching device.

[0089] It should be noted that in this embodiment, the connection between the power supply bus and the target bus is disconnected by disconnecting the first target switching device, so that the power supply bus and the target bus can work independently.

[0090] Step S26: Close the first target outgoing line switch and the second target outgoing line switch.

[0091] It should be noted that during the transition from normal operation to over-rated power operation, the disconnectors connecting the power supply bus and the receiving area remain open, as do the disconnectors connecting the target bus and the receiving area of ​​the target converter support unit. Furthermore, since the converter units connected to the power supply bus and the target bus have already been interchanged in step S24, this step only requires closing the second target outgoing switch to connect the original converter unit to the receiving area of ​​the target converter support unit via the target bus. Similarly, this step only requires closing the first target outgoing switch to connect the target support converter unit to the receiving area via the power supply bus.

[0092] Step S27: Start the target support converter unit and the original converter unit.

[0093] It should be noted that this step, by activating the converter in the target support converter unit and the converter in the original converter unit, enables the target support converter unit to start supplying power to the area to be powered, and the original converter unit to start supplying power to the area to be powered by the target support converter unit. This completes the over-rated power support for the area to be powered, and solves the technical problem that the existing flexible DC back-to-back AC field topology cannot provide over-rated power support in a timely manner when the area has an over-rated power operation requirement.

[0094] As an example, the steps for establishing a connection path between the target supporting converter unit and the power supply bus of the area to be powered, as provided in this embodiment, will be described below with reference to a topology example.

[0095] by Figure 3 Taking the topology of a four-terminal flexible back-to-back AC field as an example, as shown... Figure 3 As shown, under normal operating conditions, Unit 1 is connected to busbar #2M, and busbar #2M is connected to area 1, thus Unit 1 supplies power to area 1. Unit 2 supplies power to area 2 via busbar #1M, Unit 3 supplies power to area 3 via busbar #5M, and Unit 4 supplies power to area 4 via busbar #6M. Therefore, this topology has four power transmission channels. Among these, the outgoing switches and disconnectors on the power transmission channels are in the closed state, the remaining disconnectors are in the open state, and all switching devices and bus tie switching devices used to connect the busbars are in the open state.

[0096] The capacities of units one through four are set to 800MVA, 500MVA, 500MVA, and 500MVA respectively. Figure 6As shown. Assuming that Area 2 has a demand for over-rated power operation with a target capacity of 800MVA, and the target supporting converter unit is Unit 1, it can be seen that the capacity of Unit 1 can meet the capacity requirement of Area 2, and Unit 1 can be used alone to provide over-rated power support for Area 2. Furthermore, Unit 1 and Unit 2 are connected in the same double busbar group; therefore, the receiving area of ​​Unit 1 and the receiving area of ​​Unit 2 can be interchanged, such as... Figure 7 As shown in (a).

[0097] like Figure 7 As shown in (b) to (d), the specific operation procedure may include: blocking converters VSC1 and VSC2, and opening the outgoing switch 21 directly connected to area one and the outgoing switch 22 directly connected to area two. At this time, the topology is as follows: Figure 7 As shown in (b). The switching device 5 connecting bus #1M and bus #2M is closed, and the disconnector 31 connecting unit one and bus #1M is closed. Simultaneously, the disconnector 32 connecting unit one to bus #2M is opened, and the disconnector 33 connecting unit two to bus #2M is closed. At the same time, the disconnector 34 connecting unit two to bus #1M is opened. The topology at this time is as follows: Figure 7 As shown in (c). Disconnect the switching device 5 between bus #1M and bus #2, close the outgoing switch 21 directly connected to area 1 and the outgoing switch 22 directly connected to area 2, and start converters VSC1 and VSC2. This allows unit 1 to provide over-rated power to area 2 through bus #1M, and unit 2 to provide power to area 1 through bus #2M. This achieves over-rated power support while improving the capacity utilization of unit 2 and reducing resource waste. The topology at this time is as follows. Figure 7 As shown in (d).

[0098] Example 4 As another embodiment, in step 205 of embodiment three, the transmission bus of the target supporting converter unit is determined, and a connection path is established between the target supporting converter unit, the target bus, the bus tie switch, and the power supply bus. Specifically, this may include: S31. When there is no direct connection between the target bus and the power supply bus to the bus tie switch device, the transmission bus is regarded as the non-target bus, and the non-target bus and the target bus are in the same group of double bus.

[0099] It should be noted that when the target support converter unit and the original converter unit are not connected to the same dual busbar group, it indicates that the dual busbar groups to which the target support converter unit and the original converter unit are connected are connected through the bus tie switch device in the bus tie switch assembly. In both sets of dual busbars, each bus is connected one-to-one through the bus tie switch device. When the target busbar cannot be directly connected to the power supply busbar through the bus tie switch device, it indicates that there is no basis for direct conduction between the target busbar and the power supply busbar. Therefore, it is necessary to replace the busbar connected to the target converter support unit to enable direct conduction between the target converter support unit and the power supply busbar.

[0100] Specifically, as described in the aforementioned topology explanation, when the target bus is not connected to the power supply bus via a bus tie switch, it indicates that the non-target bus in the dual busbar system containing the target bus is connected to the power supply bus via a bus tie switch. The non-target bus refers to any bus in the dual busbar system other than the target bus. Therefore, this step treats the non-target bus as a transmission bus and, through steps S32 to S34, completes the connection between the target support converter unit and the transmission bus, thus establishing the foundation for the connection between the target support converter unit and the power supply bus.

[0101] S32. Shut down the target support converter unit and the non-target support converter unit. The non-target support converter unit refers to the converter unit that provides energy to the non-target bus under normal operating conditions.

[0102] It should be noted that this step disconnects the energy source for both the target bus and the non-target bus by shutting down the converters of both the target supporting converter unit and the non-target supporting converter unit, thereby improving operational safety.

[0103] S33. Disconnect the second target outgoing switch and the third target outgoing switch; wherein, the third target outgoing switch is an outgoing switch connected between the non-target bus and the power receiving area of ​​the non-target bus.

[0104] It should be noted that the receiving area of ​​the non-target busbar refers to the receiving area that is connected to the non-target busbar under normal operating conditions. Specifically, under normal operating conditions, the non-target support converter unit supplies power to the receiving area of ​​the non-target busbar through the non-target busbar.

[0105] This step disconnects the target busbar from the power receiving area of ​​the target support converter unit by disconnecting the second target outgoing switch; and disconnects the non-target busbar and the power receiving area of ​​the non-target busbar by disconnecting the third target outgoing switch, so that the busbar connected to the target support converter unit can be safely swapped.

[0106] S34. Close the third target switching device, open the third disconnector assembly, close the first target disconnector; and open the fourth disconnector assembly and close the fifth disconnector assembly; the third disconnector assembly includes a disconnector connected between the third target outgoing switch and the non-target bus, and a disconnector connected between the non-target bus and the non-target support converter unit; the first target disconnector is a disconnector connected between the non-target bus and the target support converter unit; the third target switching device refers to a switching device located at the end of the target bus and the non-target bus away from the power supply bus, and capable of connecting the target bus and the non-target bus; the fourth disconnector assembly includes a disconnector connected between the second target outgoing switch and the target bus, and a disconnector connected between the target bus and the target support converter unit; the fifth disconnector assembly includes a disconnector connected between the third target outgoing switch and the target bus, and a disconnector connected between the target bus and the non-target support converter unit.

[0107] It should be noted that in the topology, one end of the target bus and the non-target bus are connected to the double busbar containing the power supply bus via a bus tie switch assembly, while the other end can be interconnected via switching devices or cascaded with other double busbars via the bus tie switch assembly. Therefore, the other end of the target bus and the non-target busbar is considered to be the end furthest from the power supply busbar.

[0108] For example: Suppose that the other end of the target bus and the non-target bus is connected to only one switching device, and they are interconnected through this switching device, then the third target switching device is this switching device.

[0109] For example, suppose the other ends of the target bus and the non-target bus are respectively connected to one end of double bus 1 through bus tie switching devices, and the other end of double bus 1 is cascaded to one end of double bus 2, and the other ends of double bus 2 are interconnected through switching devices. In this topology, the third target switching device includes switching devices that connect the target bus and the non-target bus to double bus 1 respectively, switching devices that connect double bus 1 to double bus 2, and switching devices that connect two buses in double bus 2. When the other ends of the target bus and the non-target bus are cascaded with more double buses, the switching devices included in the third target switching device can also be determined based on the above principle.

[0110] This embodiment establishes a conductive connection between the target bus and the non-target bus by closing the third target switching device. Then, by disconnecting the third disconnector assembly, the connection between the non-target bus and its receiving section, as well as the connection between the non-target bus and the non-target support converter unit, is severed, thus stopping the non-target support converter unit from supplying power to the receiving section of the non-target bus. Next, by closing the first target disconnector assembly, a conductive connection is established between the non-target bus and the target support converter unit, enabling the target support converter unit to transmit power to the non-target bus, thus establishing a connection channel between the target support converter unit and the non-target bus. Finally, by disconnecting the fourth disconnector assembly, the connection between the target bus and the receiving section of the target support converter unit is severed, and the target support converter unit is completely disconnected from the target bus, thereby disconnecting the power transmission channel from the target support converter unit to its receiving section under normal operating conditions. By closing the fifth disconnector assembly, the target busbar is connected to the non-target support converter unit, and the target busbar replaces the non-target busbar and connects to the power receiving area of ​​the non-target busbar, thereby establishing a power transmission channel from the non-target support converter unit to the target busbar to the power receiving area of ​​the non-target busbar, and also establishing a power transmission channel from the target support converter unit to the non-target busbar.

[0111] Therefore, by performing this step, the target support converter unit is able to provide energy to the non-target bus, and the non-target support converter unit is able to continue to supply power to its original receiving area.

[0112] S35, Disconnect the third target switching device.

[0113] It should be noted that this step disconnects the third target switching device to break the connection between the target bus and the non-target bus, allowing the target bus and the non-target bus to operate independently.

[0114] In one example, when the third target switching device contains multiple switching devices, they are turned off in reverse order of the turn-on sequence. The turn-on sequence can be based on the distance between each device and the target bus and non-target bus, turning on from near to far.

[0115] S36. Close the bus tie switch device connected between the non-target bus and the power supply bus, and close the third target outgoing switch.

[0116] It should be noted that closing the bus tie switch device connected between the non-target bus and the power supply bus connects the non-target bus and the power supply bus, thereby connecting the target support converter unit to the power supply bus through the non-target bus, and then connecting it to the area to be powered through the power supply bus, thus completing the establishment of the power transmission channel from the target support converter unit to the non-target bus, the power supply bus, and the area to be powered.

[0117] Furthermore, this step, by closing the third target outgoing switch, establishes the power transmission channel between the non-target support converter unit, the target bus, and the non-target bus in the power receiving area.

[0118] S37. Start the target support converter unit and the non-target support converter unit.

[0119] It should be noted that this step involves activating the target support converter unit to provide power support to the receiving area of ​​the power supply bus. Simultaneously, it activates the non-target support converter units to continue supplying power to the receiving areas of the non-target bus.

[0120] The following will, with reference to the topology example of the above embodiments, exemplarily describe the steps provided in this embodiment for determining the transmission bus of the target supporting converter unit and establishing the connection path between the target supporting converter unit, the target bus, the bus tie switch and the power supply bus.

[0121] by Figure 8 Taking the topology of the four-terminal flexible back-to-back AC field shown as an example, the capacities of unit one to unit four are set to 800MVA, 500MVA, 500MVA and 500MVA respectively.

[0122] Assuming that Area 2 has a demand for operation exceeding its rated power, with a target capacity of 800MVA, and setting the target supported converter unit as Unit 4, such as... Figure 8 As shown in (a), the area to be powered is Area 2, the original converter unit of the area to be powered is Unit 2, the power supply bus is #1M, the target bus of the target supporting converter unit is #6M, the non-target bus is #5M, and the non-target supporting converter unit is Unit 3. In this case, the capacity of Unit 4 is insufficient to meet the capacity requirements of Area 2, but the sum of the capacities of Unit 4 and Unit 2 can meet the capacity requirements of Area 2. Therefore, Unit 4 and Unit 2 are used together to supply power to Area 4, achieving parallel operation. Based on Figure 8 As can be seen from the topology, the bus that is connected to the power supply bus #1M via the bus tie switch is the non-target bus #5M, not the target bus #6M of Unit 4. Therefore, it is necessary to replace the bus connected to Unit 4 so that Unit 4 can establish a connection with the power supply bus #1M.

[0123] like Figure 8 (b) to Figure 8 As shown in (e), the specific operation procedure may include: blocking converters VSC3 and VSC4, and simultaneously disconnecting the outgoing switch 24 connected to section three and the outgoing switch 23 connected to section four. At this time, the topology is as follows: Figure 8As shown in (b). Close the switch 5 connecting bus #5M and bus #6. Then, disconnect the disconnector 36 connecting unit four and bus #6M, and disconnect the disconnector 25 connecting bus #6M and area four. Close the disconnector 35 connecting unit four and bus #5M, and disconnect the disconnector 38 connecting unit three and bus #5M. Disconnect the disconnector 26 connecting bus #5M and area three, and close the disconnector 37 connecting unit three and bus #6M. Close the disconnector 27 connecting bus #6M and area three. At this time, the topology is as follows: Figure 8 As shown in (c). Disconnect switch device 5 connecting bus #5M and bus #6, close bus tie switch device 61 connecting bus #5M and bus #1M, and close outgoing switch 24 directly connected to section three. At this time, the topology is as follows. Figure 8 As shown in (d). Start converters VSC3 and VSC4, enabling unit three to supply power to area three via bus #6M, and enabling unit four to supply power to area two in parallel with converter unit two via bus #5M, exceeding the rated power. The topology at this time is as follows. Figure 8 As shown in (e).

[0124] In one possible implementation, step 205, which involves determining the transmission bus of the target supporting converter unit and establishing a connection path between the target supporting converter unit, the target bus, the bus tie switch, and the power supply bus, may specifically include: S41. When the target busbar and the power supply busbar are directly connected by a bus tie switch device, the power transmission busbar is taken as the target busbar.

[0125] It should be noted that when the target busbar and the power supply busbar are directly connected by bus tie switching devices, it indicates that there is a structural basis between the target busbar and the power supply busbar that allows for direct conduction. Therefore, the target busbar is regarded as the transmission busbar.

[0126] S42. The first switching unit connected between the target bus and the power receiving section of the target support converter unit is used as the first target switching unit.

[0127] It should be noted that in the topology, the target bus is connected to the power receiving area of ​​the target supporting converter unit through the first switching unit.

[0128] S43. Determine whether AC looping is allowed in the power receiving area of ​​the area to be powered and the power receiving area of ​​the target support converter unit; if yes, close the fourth target switch device and open the fifth target switch device; if no, shut down the target support converter unit, open the fifth target switch device, close the fourth target switch device, and then start the target support converter unit. The fourth target switching device refers to the bus tie switching device connected between the power supply bus and the target bus in the bus tie switching assembly; the fifth target switching device refers to the switching device in the first target switching unit that is in the conducting state.

[0129] It should be noted that when the receiving area of ​​the target power supply unit and the receiving area of ​​the target power supply unit are allowed to be closed in AC loop, it means that the target power supply unit can operate without power interruption. At this time, the bus tie switch device connected between the power supply bus and the target bus is closed first to establish a connection between the power supply bus and the target bus. Then, by disconnecting the fifth target switch device, the connection path between the target bus and the receiving area of ​​the target power supply unit is disconnected, so that the target bus stops transmitting power to the receiving area of ​​the target power supply unit and starts transmitting power to the power supply bus, and transmits it to the receiving area of ​​the target power supply unit through the power supply bus.

[0130] When the receiving area of ​​the waiting power receiving section and the receiving area of ​​the target support converter unit are not allowed to be closed in AC loop, the target support converter unit is first shut down to stop its operation. Then, the bus tie switch device connected between the power supply bus and the target bus is closed to establish a connection path between the power supply bus and the target bus. The fifth target switch device is then disconnected to disconnect the connection path between the target bus and the receiving area of ​​the target bus. After that, the target support converter unit is started, so that the target support converter unit transmits power to the target bus, the target bus transmits the received power to the power supply bus, and the power supply bus transmits power to the receiving area, providing power support to the receiving area.

[0131] Example 5 Accordingly, the present invention also provides a terminal device, comprising: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the over-rated power supply method based on flexible DC back-to-back AC field as described in any of the above embodiments.

[0132] The terminal device in this embodiment includes a processor, a memory, and a computer program and computer instructions stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps described in Embodiment 1 above, for example... Figure 4 Steps S101 to S105 are shown.

[0133] For example, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0134] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the schematic diagram is merely an example of a terminal device and does not constitute a limitation on the terminal device. It may include more or fewer components than illustrated, or combine certain components, or different components. For example, the terminal device may also include input / output devices, network access devices, buses, etc.

[0135] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0136] The memory can be used to store the computer programs and / or modules. The processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and by calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, applications required for at least one function, etc.; the data storage area may store data created based on the use of the mobile terminal, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital card (SD card), flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0137] Wherein, if the modules / units integrated in the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, it can implement the steps of the various method embodiments described above. Wherein, the computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content contained in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0138] Example 6 Accordingly, the present invention also provides a computer-readable storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the over-rated power supply method based on flexible DC back-to-back AC field as described in any of the above embodiments.

[0139] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the topologies, systems, modules, or units described in the above embodiments can be referred to the corresponding processes in the method embodiments, and will not be repeated here.

[0140] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0141] It should also be noted that in the description of this invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or connection relationship based on the orientation or connection relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0142] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for supplying power exceeding rated capacity based on a flexible DC back-to-back AC field, characterized in that, Applications include flexible back-to-back AC field topologies, including: When any area is operating at above-rated power, an over-power supply command is generated. Based on the excess power supply instruction, the area to be powered, the original converter unit of the area to be powered, and the target support converter unit are determined; Obtain the target capacity of the area to be powered and the rated capacity of the target supporting converter unit; Adjust the connection status between the original converter unit and the area to be powered based on the target capacity and the rated capacity; Establish a connection path between the target supporting converter unit and the area to be powered.

2. The method for supplying over-rated power based on a flexible DC back-to-back AC field as described in claim 1, characterized in that, The step of adjusting the connection status between the original converter unit and the area to be powered based on the target capacity and the rated capacity specifically includes: If the rated capacity is not less than the target capacity, then disconnect the original converter unit from the area to be powered. When the rated capacity is less than the target capacity, the connection between the original converter unit and the area to be powered is maintained.

3. The method for supplying over-rated power based on a flexible back-to-back AC field as described in claim 2, characterized in that, The construction of the connection path between the target supporting converter unit and the area to be powered specifically includes: Determine whether a bus tie switch assembly exists on the power transmission channel between the target supporting converter unit and the power receiving area; If not, establish a connection path between the target support converter unit and the power supply bus of the area to be powered. If so, determine the transmission bus of the target supporting converter unit, and establish a connection path between the target supporting converter unit, the transmission bus, the bus tie switch assembly, and the power supply bus.

4. The method for supplying over-rated power based on a flexible back-to-back AC field as described in claim 3, characterized in that, The flexible back-to-back AC field topology includes: at least two sets of dual buses; Each group of dual busbars includes two busbars; each busbar is connected to a section via a first switching unit; each busbar is connected to a converter unit via a second switching unit; the DC sides of each converter unit are interconnected; each group of dual busbars is cascaded via a bus tie switch assembly; wherein, one end of the two busbars of the first dual busbar is interconnected via a switching device; the other end of the two busbars of the last dual busbar is interconnected via the switching device.

5. The method for supplying over-rated power based on a flexible back-to-back AC field as described in claim 4, characterized in that, The first switching unit includes a first outgoing switch, a first disconnect switch, and a second disconnect switch; One end of the first outgoing switch is connected to the area; The other end of the first outgoing switch is connected to the first disconnect switch and the second disconnect switch, respectively; The first disconnector is connected to one of the two busbars; The second disconnector is connected to the other busbar in the dual busbar system.

6. The method for supplying over-rated power based on a flexible DC back-to-back AC field as described in claim 5, characterized in that, The second switching unit includes a second outgoing switch, a third disconnect switch, and a fourth disconnect switch; One end of the second outgoing switch is connected to the converter unit; The other end of the second outgoing switch is connected to the third disconnect switch and the fourth disconnect switch respectively; The third disconnector is connected to one of the two busbars; The fourth disconnector is connected to the other busbar in the dual busbar system.

7. The method for supplying over-rated power based on a flexible DC back-to-back AC field as described in claim 6, characterized in that, The bus tie switch assembly includes two bus tie switch devices; The aforementioned bus tie switch device is respectively connected to one bus in a double busbar and one bus in another double busbar; Another bus tie switch device is connected to the other bus in one of the double busbars and the other bus in the other double busbar.

8. The method for supplying over-rated power based on a flexible DC back-to-back AC field as described in claim 7, characterized in that, The establishment of a connection path between the target support converter unit and the power supply bus of the area to be powered specifically includes: Shut down the target supporting converter unit and the original converter unit; Disconnect the first target outgoing line switch and the second target outgoing line switch; The first target switching device for closing the circuit; Close the first disconnect switch assembly and disconnect the second disconnect switch assembly; Disconnect the first target switching device; Close the first target output switch and the second target output switch; Start the target supporting converter unit and the original converter unit; Wherein, the first target outgoing switch is an outgoing switch directly connected to the power receiving area, and the second target outgoing switch is an outgoing switch directly connected to the power receiving area of ​​the target support converter unit under normal operating conditions. The first target switching device is a switching device that connects the power supply bus and the target bus; the target bus is a bus that is connected to the target support converter unit under normal operating conditions. The first disconnector assembly includes a disconnector connected to the original converter unit and the target bus, and a disconnector connected to the target support converter unit and the power supply bus; The second disconnector assembly includes a disconnector connected to the original converter unit and the power supply bus, and a disconnector connected to the target support converter unit and the power supply bus.

9. A method for supplying over-rated power based on a flexible DC back-to-back AC field as described in claim 8, characterized in that, The step of determining the transmission bus of the target supporting converter unit and establishing the connection path between the target supporting converter unit, the target bus, the bus tie switch, and the power supply bus specifically includes: When the target busbar and the power supply busbar are not directly connected by the bus tie switch device, the power transmission busbar is regarded as a non-target busbar, and the non-target busbar and the target busbar are in the same group of double busbars; Shutting down the target support converter unit and the non-target support converter unit; wherein, the non-target support converter unit is the converter unit that provides energy to the non-target bus under normal operating conditions; Disconnect the second target outgoing switch and the third target outgoing switch; wherein, the third target outgoing switch is an outgoing switch connected between the non-target bus and the power receiving area of ​​the non-target bus; Close the third target switching device, disconnect the third disconnector assembly, close the first target disconnector; and disconnect the fourth disconnector assembly and close the fifth disconnector assembly. Disconnect the third target switching device; Close the bus tie switch device connected between the non-target bus and the power supply bus, and close the third target outgoing switch; Start the target support converter unit and the non-target support converter unit; The third disconnector assembly includes a disconnector connected between the third target outgoing switch and the non-target bus, and a disconnector connected between the non-target bus and the non-target support converter unit; the first target disconnector is a disconnector connected between the non-target bus and the target support converter unit; the third target switching device is a switching device located at the end of the target bus and the non-target bus away from the power supply bus, and is used to connect the target bus and the non-target bus; the fourth disconnector assembly includes a disconnector connected between the second target outgoing switch and the target bus, and a disconnector connected between the target bus and the target support converter unit; the fifth disconnector assembly includes a disconnector connected between the third target outgoing switch and the target bus, and a disconnector connected between the target bus and the non-target support converter unit.

10. A method for supplying over-rated power based on a flexible DC back-to-back AC field as described in claim 9, characterized in that, The step of determining the transmission bus of the target supporting converter unit and establishing a connection path between the target supporting converter unit, the target bus, the bus tie switch, and the power supply bus specifically includes: When the target busbar and the power supply busbar are directly connected by a bus tie switch device, the power transmission busbar is the target busbar; The first switching unit connected between the target bus and the power receiving area of ​​the target support converter unit is designated as the first target switching unit. Determine whether AC looping is permitted between the power receiving area to be powered and the power receiving area of ​​the target supported converter unit; If so, close the fourth target switch and open the fifth target switch; If not, shut down the target support converter unit, disconnect the fifth target switching device, and close the fourth target switching device, thereby starting the target support converter unit; The fourth target switching device is a bus tie switching device connected between the power supply bus and the target bus in the bus tie switching assembly; the fifth target switching device is a switching device in the first target switching unit that is in the conducting state.

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