Power transmission systems, control methods, equipment and media

Abstract

This application discloses a power transmission system, control method, equipment, and medium. The power transmission system includes: a DC bus, comprising a first DC bus, a second DC bus, and a medium-voltage DC bus, the medium-voltage DC bus being electrically connected to a reference voltage terminal; one of the first DC bus and the second DC bus being a positive DC bus, and the other being a negative DC bus; a grid-commutated converter, connected in series between the first DC bus and the medium-voltage DC bus, the grid-commutated converter being used to transmit power to a high-voltage AC grid; and a DC transformer, connected in series between the second DC bus and the medium-voltage DC bus, the DC transformer being used to output DC power to a load. The above power transmission system can improve power utilization efficiency.

Description

Technical Field

[0001] This application belongs to the field of power transmission technology, and in particular relates to a power transmission system, control method, equipment and medium. Background Technology

[0002] High Voltage Direct Current (HVDC) transmission technology has become one of the important transmission methods in modern power systems due to its low loss, high stability, and flexible current control capabilities. To utilize HVDC-enabled DC grids, they need to be integrated into AC grids. Traditionally, integrating a DC grid into an AC grid requires building an AC substation and using a Modular Multilevel Converter (MMC) as the converter to achieve this integration.

[0003] However, MMC and its supporting equipment require a large amount of land, making them difficult to deploy in areas with scarce land resources such as cities. At the same time, the above solution requires the setting up of DC power grids, AC substations, multi-level transformers, and multi-level connections to the AC power grid, resulting in significant energy loss during multiple conversion processes. Summary of the Invention

[0004] This application provides a power transmission system, control method, device, equipment, medium, and product that can improve power utilization.

[0005] In a first aspect, embodiments of this application provide a power transmission system, including: The DC bus includes a first DC bus, a second DC bus, and a medium-voltage DC bus. The medium-voltage DC bus is electrically connected to the reference voltage terminal. One of the first DC bus and the second DC bus is a positive DC bus, and the other is a negative DC bus. A grid-commutated converter is connected in series between the first DC bus and the medium-voltage DC bus. The grid-commutated converter is used to transmit power to the high-voltage AC grid. A DC transformer is connected in series between the second DC bus and the medium-voltage DC bus. The DC transformer is used to output DC power to the load.

[0006] Secondly, embodiments of this application provide a control method for a power transmission system, which, when applied to any of the aforementioned power transmission systems in the first aspect, includes: When the grid commutator and DC transformer are not started, control the load to start and adjust the load parameters to control the load output voltage to the rated voltage of the medium voltage DC bus. Control the DC transformer to start, adjust the parameters of the DC transformer to control the output power of the DC transformer to the preset power, and control the second DC bus to be electrically connected to the DC transformer; Once it is determined that the voltage of the medium-voltage DC bus is stable, the grid-commutated converter is started, the parameters of the grid-commutated converter are adjusted to control the output power of the grid-commutated converter to the preset power, and the electrical connection between the first DC bus and the grid-commutated converter is controlled.

[0007] Thirdly, embodiments of this application provide a control device for a power transmission system, comprising: Control unit, used for: When the grid commutator and DC transformer are not started, control the load to start and adjust the load parameters to control the load output voltage to the rated voltage of the medium voltage DC bus. Control the DC transformer to start, adjust the parameters of the DC transformer to control the output power of the DC transformer to the preset power, and control the second DC bus to be electrically connected to the DC transformer; Once it is determined that the voltage of the medium-voltage DC bus is stable, the grid-commutated converter is started, the parameters of the grid-commutated converter are adjusted to control the output power of the grid-commutated converter to the preset power, and the electrical connection between the first DC bus and the grid-commutated converter is controlled.

[0008] Fourthly, embodiments of this application provide an electronic device, the device comprising: Processor and memory storing computer program instructions; The processor executes computer program instructions to perform the control method of the power transmission system described in the second aspect above.

[0009] Fifthly, embodiments of this application provide a computer storage medium storing computer program instructions, which, when executed by a processor, implement the control method for the power transmission system described in the second aspect.

[0010] In a sixth aspect, embodiments of this application provide a computer program product, including a computer program that, when processed by a processor, implements the control method for the power transmission system described in the second aspect.

[0011] The power transmission system, control method, apparatus, equipment, medium, and products provided in this application, by setting up a power transmission system including a DC bus, a grid commutation converter, and a DC transformer, can reduce multi-stage energy conversion and improve power utilization. Furthermore, based on the small size of DC transformers, they can be deployed within cities to directly supply DC power to urban loads, saving valuable land resources in city centers. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of a power transmission system provided for some embodiments of this application.

[0014] Figure 2 This is a schematic diagram of another power transmission system provided for some embodiments of this application.

[0015] Figure 3 This is a schematic diagram of yet another power transmission system provided for some embodiments of this application.

[0016] Figure 4 This is a flowchart illustrating a control method for a power transmission system provided in some embodiments of this application.

[0017] Figure 5 This is a schematic diagram of a control device for a power transmission system provided in some embodiments of this application.

[0018] Figure 6 This is a schematic diagram of the hardware structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0019] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0020] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0021] In the process of connecting high-voltage direct current (HVDC) transmission systems to the AC power grid, and in the process of grid connection between the HVDC and AC power grids, traditional grid connection schemes typically rely on a complex energy conversion path involving HVDC, high-voltage AC, multi-stage transformers, and medium-voltage AC. This multi-stage conversion architecture results in significant energy losses. Furthermore, because deploying this energy conversion path requires various types of equipment, it necessitates the use of substantial amounts of valuable land resources in urban centers where land is scarce, leading to extremely difficult site selection and high construction costs. Moreover, as load density in urban centers continues to increase, the various devices in this conversion path also exhibit poor safety and stability.

[0022] Based on this, embodiments of this application provide a power transmission system, control method, apparatus, equipment, medium, and product that can solve the above-mentioned problems.

[0023] The following is a detailed description of a power transmission system provided in the embodiments of this application.

[0024] like Figure 1 As shown, embodiments of this application provide a method as described above. Figure 1 The power transmission system may include: The DC bus includes a first DC bus 101, a second DC bus 102 and a medium-voltage DC bus 103. The medium-voltage DC bus 103 is electrically connected to the reference voltage terminal GND. One of the first DC bus 101 and the second DC bus 102 is a positive DC bus and the other is a negative DC bus.

[0025] The grid-commutated converter 20 is connected in series between the first DC bus 101 and the medium-voltage DC bus 103. The grid-commutated converter 20 is used to transmit power to the high-voltage AC grid.

[0026] DC transformer 30 is connected in series between the second DC bus 102 and the medium-voltage DC bus 103. DC transformer 30 is used to output DC power to the load.

[0027] Here, the aforementioned line commutated converter (LCC) is a device that can convert DC power into high-voltage AC power. It can stably clamp the voltage of the high-voltage DC bus at the rated value, thereby enabling power transmission to the high-voltage AC grid.

[0028] The aforementioned DC transformer 30 (DCT) is a device capable of providing stable DC power to the load. It can directly provide DC power to the load by adjusting its parameters, such as the voltage ratio.

[0029] The first DC bus 101 and the second DC bus 102 mentioned above are either positive DC buses or negative DC buses. For example, if the first DC bus 101 is a positive DC bus, then the second DC bus 102 is a negative DC bus; or if the first DC bus 101 is a negative DC bus, then the second DC bus 102 is a positive DC bus.

[0030] The aforementioned power transmission system is configured such that its startup logic can be: When the grid-commutator 20 and DC transformer 30 are not started, and the first DC bus 101 and the second DC bus 102 are not electrically connected to the grid-commutator 20 and DC transformer 30, the load can be started and the load parameters can be adjusted to control the output voltage of the load to the rated voltage of the medium-voltage DC bus 103, so that it can establish the rated voltage of the medium-voltage DC bus 103; the above-mentioned load is a device that can start and output AC power based on the medium-voltage AC grid, such as a DC / AC converter.

[0031] Secondly, the DC transformer 30 can be controlled to start from the medium-voltage DC bus 103. By adjusting the parameters of the DC transformer 30, the output power of the DC transformer 30 can be controlled to the preset power, and the second DC bus 102 can be electrically connected to the DC transformer 30, that is, the DC transformer 30 and the second DC bus 102 can be controlled to close. Furthermore, once it is determined that the voltage of the medium-voltage DC bus 103 is in a stable state, the grid phase-commutation converter 20 can be started, and the parameters of the grid phase-commutation converter 20 can be adjusted, such as adjusting its firing angle parameter, to control the output power of the grid phase-commutation converter 20 to the preset power, and control the electrical connection between the first DC bus 101 and the grid phase-commutation converter 20, that is, control the grid phase-commutation converter 20 and the first DC bus 101 to close.

[0032] In some examples, when the DC system is in a stable operating state, in order to avoid excessive current being generated on the medium-voltage DC bus 103, the output power of the DC transformer 30 can be controlled to be the same as the output power of the grid-commutated converter 20.

[0033] In some examples, such as Figure 2 As shown, Figure 2 This is a schematic diagram of another exemplary power transmission system.

[0034] like Figure 2 In this context, the aforementioned DC transformer 30 can be installed in cities, such as underground in the city center, while the grid phase converter 20, due to the large size of its related equipment, can be installed in suburban areas with abundant land resources.

[0035] This application embodiment, by setting up a power transmission system including a DC bus, a grid-commutated converter, and a DC transformer, reduces multi-stage energy conversion and improves power utilization by connecting the DC bus, grid-commutated converter, and AC grid. Furthermore, due to the small size of the DC transformer, this power transmission system can be deployed within the city, directly supplying DC power to urban loads and saving valuable land resources in the city center.

[0036] In some embodiments, such as Figure 3 As shown, Figure 3 This is a schematic diagram of another type of power transmission system, such as Figure 3 In this process, the load may include a DC-AC converter 40, which is used to convert the DC power output from the DC transformer 30 into AC power and input AC power into the medium-voltage AC power grid.

[0037] The aforementioned DC-AC converter 40 is a device that can convert DC power into AC power, and it can be electrically connected to a medium-voltage AC power grid. Here, the medium-voltage AC power grid is electrically isolated from the high-voltage AC power grid.

[0038] Here, under the circumstances where the grid commutator 20 and DC transformer 30 are not started, and the first DC bus 101 and the second DC bus 102 are not electrically connected to the grid commutator 20 and DC transformer 30, the DC-AC converter 40 can be started and its parameters adjusted, such as adjusting the voltage modulation ratio or switching frequency, to control the load output voltage to the rated voltage of the medium-voltage DC bus 103, so that it can establish the rated voltage of the medium-voltage DC bus 103.

[0039] This application embodiment enables grid connection between a DC power grid and a medium-voltage AC power grid by setting a load including a DC-AC converter. Based on the established electrical connection of the DC bus, DC transformer and DC-AC converter, the loss of electrical energy during energy level conversion can be reduced and the power utilization rate can be improved.

[0040] In some embodiments, such as Figure 3 As shown, the DC-AC converter 40 includes at least two DC-AC converters 40, which are connected in parallel between the DC transformer 30 and the medium-voltage AC power grid.

[0041] like Figure 3 In this configuration, at least two DC-AC converters 40 can be electrically connected to the same medium-voltage AC power grid to supply power to it; alternatively, at least two DC-AC converters 40 can be connected to different medium-voltage AC power grids. The first DC-AC converter 40 is electrically connected to a first medium-voltage AC power grid, and the second DC-AC converter 40 is electrically connected to a second medium-voltage AC power grid, allowing them to supply power to different medium-voltage AC power grids respectively. Here, the first and second medium-voltage AC power grids can be electrically isolated.

[0042] This application embodiment, by setting a DC-AC converter including at least two DC-AC converters, can adapt to the diverse output of the power system. At the same time, in the event of a failure of any one DC-AC converter, the stable operation of the entire power transmission system can be achieved by adjusting the output power of the other DC-AC converters.

[0043] In some embodiments, such as Figure 4 As shown, this application provides a control method for a power transmission system, applicable to any of the aforementioned power transmission systems. The control method may include: S410: When the grid commutator and DC transformer are not started, control the load to start and adjust the load parameters to control the load output voltage to the rated voltage of the medium voltage DC bus.

[0044] When the grid commutator and DC transformer are not started, that is, when both devices are not in operation and not electrically connected to the DC bus, the load can be controlled to start. Both the load and the DC transformer have bidirectional power transmission capability.

[0045] In some examples, the aforementioned load can be a DC charging device, a server, or other device that requires DC power. The parameters of the device, such as the voltage control ratio parameter, can be controlled, and its output voltage can be monitored in real time (i.e., the voltage connected to one side of the DC transformer) so that its output voltage can reach the rated voltage of the medium-voltage DC bus, thereby establishing a stable medium-voltage DC bus voltage.

[0046] In some examples, the aforementioned load can be a device capable of AC-DC conversion, such as a DC-AC converter that can be electrically connected to a medium-voltage AC power grid. During the startup process, the DC-AC converter can be started by controlling it to output AC power from the medium-voltage AC power grid, and the parameters of the DC-AC converter can be adjusted, such as adjusting the voltage modulation ratio or switching frequency, so that its output voltage can reach the rated voltage of the medium-voltage DC bus.

[0047] S420: Controls the start-up of the DC transformer, adjusts the parameters of the DC transformer to control the output power of the DC transformer to the preset power, and controls the electrical connection between the second DC bus and the DC transformer.

[0048] The system can control the DC transformer to start from the medium-voltage side, adjust its parameters such as the transformation ratio, and achieve a preset output power through dual-loop control of its current and output voltage. Once the preset output power is reached, the system controls the second DC bus to electrically connect to the DC transformer, thus connecting the DC transformer to the DC power grid.

[0049] S430: When the voltage of the medium-voltage DC bus is determined to be stable, start the grid-commutated converter, adjust the parameters of the grid-commutated converter to control the output power of the grid-commutated converter to the preset power, and control the electrical connection between the first DC bus and the grid-commutated converter.

[0050] It can continuously monitor the voltage of the medium-voltage DC bus. Once it is determined that the voltage is in a stable state, i.e., the voltage fluctuation rate is less than the preset threshold, the grid commutation converter can be started, and the parameters of the grid commutation converter, such as the firing angle parameter, can be adjusted to gradually increase its output power to the preset power.

[0051] In this embodiment, based on the above control method, the load is first started. After the output voltage of the load reaches the rated voltage of the medium-voltage DC bus, the DC transformer is started so that it can establish a stable medium-voltage DC target voltage. At the same time, the necessary starting current is provided for the grid commutation converter. Then the grid commutation converter is started, which can avoid its commutation failure, thereby stabilizing the start of the power transmission system.

[0052] In some embodiments, the control method described above may further include: When the power transmission system is in a stable operating state, the output power of the grid phase converter is obtained and used as the output power reference value; the load parameters are adjusted to control the load output power as the output power reference value.

[0053] Here, the above-mentioned power transmission system maintains a stable operating state while satisfying the following expression: P 负载 =P LCC (1) P LCC P is the output power reference value. 负载 This represents the output power of the load.

[0054] Here, taking the example of a DC transformer electrically connected to the positive DC bus and a grid commutation converter electrically connected to the negative DC bus, the negative DC current I can be collected when the above-mentioned power transmission system is in a stable operating state. LCC (i.e., negative DC bus current), positive DC voltage U dc The positive DC current feedback quantity (i.e., the positive DC bus current) is based on the negative DC current I. LCC and positive DC voltage U dc The output power of the grid-commutated converter is determined and used as a reference value. To improve the accuracy of this reference value, a power correction factor can be determined based on the positive DC current feedback. This correction factor is then used to adjust the output power reference value, resulting in a new reference value. Finally, the load parameters are adjusted to control the load's output power to match this new reference value.

[0055] In some examples, the positive DC current feedback can be input to a proportional-integral (PI) controller to obtain the power correction.

[0056] The embodiments of this application achieve consistency between the output power of the load and the output power of the grid phase-commutation converter by means of the above method, which helps to reduce the current of the medium-voltage DC bus and improve the operational stability of the power transmission system.

[0057] In some embodiments, the load includes a DC-AC converter for converting DC power output from a DC transformer into AC power and inputting AC power into a medium-voltage AC power grid.

[0058] The aforementioned loads may include DC-AC converters. It is conceivable that when the aforementioned grid phase converters and DC transformers are not started, the DC-AC converters can be started first to establish a stable medium-voltage DC bus voltage.

[0059] Meanwhile, when the aforementioned DC transmission system is in a stable operating state, the output power of the DC-AC converter can be adjusted to the reference value by adjusting the parameters of the DC-AC converter.

[0060] Here, the output power mentioned above refers to active power.

[0061] This application embodiment, by setting the above-mentioned load to include a DC-AC converter, can realize the integration of the DC grid into the medium-voltage AC grid. At the same time, based on the bidirectional power transmission capability of the DC-AC converter, it can realize the normal start-up of the power transmission system. Furthermore, when the power transmission system is in a stable operating state, it can adjust the period parameters to keep the power of the power transmission system balanced.

[0062] In some embodiments, the DC-AC converter includes at least two DC-AC converters connected in parallel between a DC transformer and a medium-voltage AC power grid. The control method may further include: If a fault is detected in the target DC-AC converter, disconnect the electrical connection between the DC transformer and the target DC-AC converter, where the target DC-AC converter is any one of at least two DC-AC converters; adjust the parameters of the first DC-AC converter and / or the parameters of the grid commutation converter to control the output power of the first DC-AC converter to be the same as the output power of the grid commutation converter, where the first DC-AC converter is any one of at least two DC-AC converters other than the target DC-AC converter.

[0063] It is conceivable that when the above-mentioned power transmission system is in a stable operating state, the operating status of different equipment in the power transmission system can be continuously monitored. If it is determined that the target DC-AC converter is in a fault state, such as when its output voltage, output current, or temperature is abnormal, it is considered to be in a fault state. The electrical connection between the target DC-AC converter and the DC transformer can be cut off in time to isolate the fault.

[0064] Here, the output power of the grid-commutated converter can be adjusted to redetermine the output power reference value, thereby further adjusting the output power of the first DC-AC converter based on the redetermined output power reference value; alternatively, only the parameters of the first DC-AC converter can be adjusted to make its output power the same as the current output power of the grid-commutated converter; or only the parameters of the grid-commutated converter can be adjusted to make its output power the same as the current output power of the first DC-AC converter. These adjustment strategies can be flexibly set based on actual needs, and will not be elaborated further here.

[0065] This embodiment of the application achieves rapid fault isolation and prevents fault escalation by promptly disconnecting the electrical connection between the target DC-AC converter and the DC transformer when the target DC-AC converter is determined to be in a faulty state. Simultaneously, by adjusting the parameters of the first DC-AC converter and / or the grid-commutated converter, the output power of the first DC-AC converter is made the same as that of the grid-commutated converter, thereby redistributing power to maintain the stable operation of the transmission system.

[0066] In some embodiments, the control method may further include: If a fault is detected in the DC transformer, the parameters of the grid-commutated converter are adjusted to reduce the output power of the grid-commutated converter as the reference power.

[0067] When abnormal fluctuations in current, voltage, or temperature are detected in a DC transformer, it can be determined that the transformer is in a fault state. The parameters of the grid-commutated converter, such as the firing angle parameter, can be adjusted to reduce the output power of the grid-commutated converter.

[0068] In some examples, when the aforementioned DC transformer is in a fault state, its electrical connection to the DC bus can be quickly shut off to rapidly isolate the fault.

[0069] At the same time, the status of the DC transformer can be continuously monitored. Once it is determined that the transformer has returned to normal, the parameters of the grid commutator can be adjusted to restore the output power to the value when the power transmission system is in a stable operating state.

[0070] This application embodiment reduces the output power of the grid commutator when a fault is detected in the DC transformer. This allows the DC transformer to transmit power to the high-voltage AC grid, ensuring normal power supply to users on the high-voltage AC grid side, while maintaining its operating state so that its output power can be restored to the value when the power transmission system is in a stable operating state after the DC transformer is restored to normal.

[0071] Based on the same inventive concept, embodiments of this application also provide a control device for a power transmission system.

[0072] In some embodiments, such as Figure 5 As shown in the figure, this application provides a control device for a power transmission system, which may include: Control unit 501 is used for: With the grid-commutated converter and DC transformer not started, the load is started and its parameters are adjusted to control the output voltage of the load to the rated voltage of the medium-voltage DC bus; the DC transformer is started and its parameters are adjusted to control the output power of the DC transformer to a preset power, and the second DC bus is electrically connected to the DC transformer; when the voltage of the medium-voltage DC bus is determined to be stable, the grid-commutated converter is started and its parameters are adjusted to control the output power of the grid-commutated converter to a preset power, and the first DC bus is electrically connected to the grid-commutated converter.

[0073] Based on the above control device, stable startup of the power transmission system can be achieved, while also reducing the risk of commutation failure of the grid commutator.

[0074] In some embodiments, the control unit is further configured to: When the power transmission system is in a stable operating state, the output power of the grid phase converter is obtained and used as the output power reference value; the load parameters are adjusted to control the load output power to be the output power reference value.

[0075] In some embodiments, the control unit is further configured to: The load includes a DC-AC converter, which is used to convert the DC power output from the DC transformer into AC power and input the AC power into the medium-voltage AC power grid.

[0076] In some embodiments, the DC-AC converter includes at least two DC-AC converters connected in parallel between the DC transformer and the medium-voltage AC grid. The control unit is further configured to: If a fault is detected in the target DC-AC converter, the electrical connection between the DC transformer and the target DC-AC converter is disconnected. The target DC-AC converter is any one of at least two DC-AC converters. Adjust the parameters of the first DC-AC converter and / or the grid-commutated converter to control the output power of the first DC-AC converter to be the same as the output power of the grid-commutated converter. The first DC-AC converter is a DC-AC converter other than the target DC-AC converter among at least two DC-AC converters.

[0077] In some embodiments, the control unit is further configured to: If a fault is detected in the DC transformer, the parameters of the grid-commutated converter are adjusted to reduce the output power of the grid-commutated converter to a reference power.

[0078] The apparatus of the above embodiments is used to implement the control method of the corresponding power transmission system in any of the foregoing embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0079] Figure 6 A schematic diagram of the hardware structure of an electronic device is provided in the application embodiment.

[0080] The electronic device 600 may include a processor 601 and a memory 602 storing computer program instructions.

[0081] Specifically, the processor 601 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0082] Memory 602 may include mass storage for data or instructions. For example, and not limitingly, memory 602 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 602 may include removable or non-removable (or fixed) media. Where appropriate, memory 602 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 602 is non-volatile solid-state memory.

[0083] In a particular embodiment, memory 602 includes read-only memory (ROM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM), or flash memory, or a combination of two or more of these.

[0084] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to the first aspect of this application.

[0085] The processor 601 reads and executes computer program instructions stored in the memory 602 to implement any of the power transmission system control methods in the above embodiments.

[0086] In one example, the electronic device may also include a communication interface 603 and a bus 604. Wherein, as... Figure 6 The processor 601, memory 602, and communication interface 603 are connected through bus 604 and complete communication with each other.

[0087] The communication interface 603 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0088] Bus 604 includes hardware, software, or both, that couples components of an online data traffic metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 604 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0089] The electronic devices described above are used to implement the control methods of the corresponding power transmission systems in any of the foregoing embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0090] Furthermore, in conjunction with the power transmission system control methods in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the power transmission system control methods in the above embodiments.

[0091] Furthermore, in conjunction with the power transmission system control methods described in the above embodiments, this application can provide a computer program product for implementation. When the instructions of this computer program product are executed by the processor of an electronic device, they implement any of the power transmission system control methods described in the above embodiments.

[0092] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0093] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0094] It should also be noted that the exemplary embodiments mentioned in this application describe methods or apparatuses based on a series of steps or devices. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0095] The aspects of this application have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of this application. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by dedicated hardware performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0096] The above description is merely a specific embodiment of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A power transmission system, characterized in that, include: The DC bus includes a first DC bus, a second DC bus, and a medium-voltage DC bus. The medium-voltage DC bus is electrically connected to the reference voltage terminal. One of the first DC bus and the second DC bus is a positive DC bus, and the other is a negative DC bus. A grid-commutated converter is connected in series between the first DC bus and the medium-voltage DC bus, and is used to transmit power to the high-voltage AC grid. A DC transformer is connected in series between the second DC bus and the medium-voltage DC bus, and the DC transformer is used to output DC power to the load.

2. The power transmission system according to claim 1, characterized in that, The load includes a DC-AC converter, which is used to convert the DC power output from the DC transformer into AC power and input the AC power into the medium-voltage AC power grid.

3. The power transmission system according to claim 2, characterized in that, The DC-AC converter includes at least two DC-AC converters, which are connected in parallel between the DC transformer and the medium-voltage AC power grid.

4. A control method for a power transmission system, characterized in that, The control method, applied to the power transmission system according to any one of claims 1-3, comprises: When the grid commutator and DC transformer are not started, the load is started and the parameters of the load are adjusted to control the output voltage of the load to the rated voltage of the medium voltage DC bus. The DC transformer is started, its parameters are adjusted to control its output power to a preset power, and the second DC bus is electrically connected to the DC transformer. Once it is determined that the voltage of the medium-voltage DC bus is in a stable state, the grid phase-commutation converter is started, the parameters of the grid phase-commutation converter are adjusted to control the output power of the grid phase-commutation converter to a preset power, and the electrical connection between the first DC bus and the grid phase-commutation converter is controlled.

5. The control method for a power transmission system according to claim 4, characterized in that, Also includes: When the power transmission system is in a stable operating state, the output power of the grid phase converter is obtained and used as a reference value for the output power. Adjust the load parameters to control the load's output power to the aforementioned output power reference value.

6. The control method for a power transmission system according to claim 4 or 5, characterized in that, The load includes a DC-AC converter, which is used to convert the DC power output from the DC transformer into AC power and input the AC power into the medium-voltage AC power grid.

7. The control method for a power transmission system according to claim 6, characterized in that, The DC-AC converter includes at least two DC-AC converters, which are connected in parallel between the DC transformer and the medium-voltage AC power grid. The control method further includes: If a fault is detected in the target DC-AC converter, the electrical connection between the DC transformer and the target DC-AC converter is disconnected. The target DC-AC converter is any one of at least two DC-AC converters. Adjust the parameters of the first DC-AC converter and / or the grid-commutated converter to control the output power of the first DC-AC converter to be the same as the output power of the grid-commutated converter. The first DC-AC converter is a DC-AC converter other than the target DC-AC converter among at least two DC-AC converters.

8. The control method for a power transmission system according to claim 4 or 5, characterized in that, Also includes: If a fault is detected in the DC transformer, the parameters of the grid-commutated converter are adjusted to reduce the output power of the grid-commutated converter to a reference power.

9. An electronic device, characterized in that, The device includes: a processor, and a memory storing computer program instructions; The processor reads and executes the computer program instructions to implement the control method of the power transmission system as described in any one of claims 4 to 8.

10. A readable storage medium, characterized in that, The readable storage medium stores computer program instructions, which, when executed by a processor, implement the control method for the power transmission system as described in any one of claims 4 to 8.

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