Medium-voltage flexible interconnection system with ice melting function, and ice melting method and system

Abstract

The invention discloses a medium-voltage flexible interconnection system with an ice melting function and an ice melting method and system, and relates to the technical field of power electronics, the key points of the technical scheme are that the interconnection system comprises a plurality of power electronic transformers, AC input ends of the plurality of power electronic transformers are respectively connected with a plurality of power grids, and the AC input ends of the plurality of power electronic transformers are connected with the plurality of power grids; the direct-current output ends are connected with the same direct-current bus; the power electronic transformer comprises a plurality of converter groups, and the power electronic transformer has a working mode and an ice melting mode. The energy storage equipment is connected with the direct current bus; and the controller is configured to respond to an ice melting condition, control one of the power electronic transformers to be switched to an ice melting mode, and at least control the energy storage equipment to supply power to one of the power electronic transformers. Through the interconnection system, interconnection and energy interaction of different power grid areas can be realized, the capability of independently carrying out power distribution line ice melting is realized, a line ice melting device does not need to be additionally installed, the operation is simple, and the investment of a power distribution network is effectively reduced.

Description

Technical Field

[0001] This disclosure relates to the field of power electronics technology, and in particular to a medium-voltage flexible interconnection system with de-icing function, a de-icing method and system. Background Technology

[0002] Medium-voltage flexible interconnection systems primarily refer to the flexible interconnection of medium-voltage power supply lines on the feeder side of the distribution network, which enhances the network's power supply structure adjustment capabilities and improves power supply reliability. Flexible interconnection devices enable intelligent interaction of power and energy between different power supply zones, allowing for flexible cross-regional dispatching between different or equal voltage levels in asynchronous power grids. This effectively improves the power transmission efficiency of distributed power sources, further enhancing system energy efficiency; simultaneously, it avoids stability issues such as overvoltage caused by transformer power backfeeding.

[0003] When the air temperature near the ground is below freezing, but the air temperature at higher altitudes is above freezing, raindrops falling on power transmission lines will form an ice layer on them. Ice accumulation significantly increases the weight of the transmission lines, causing additional mechanical stress on the lines and transmission towers. If the ice buildup is too heavy, it may cause the transmission lines to break or the transmission towers to collapse, resulting in power outages and costly repairs. Therefore, de-icing transmission lines is a crucial measure to ensure reliable power grid operation, prevent power system failures, and protect the surrounding environment and public safety. In existing technologies, short-circuit de-icing is a method for de-icing transmission lines. Its core idea is to use the Joule heating effect of a large current to heat the conductors, melting the ice on the line. This typically requires providing a large current at a low voltage. Existing AC short-circuit de-icing schemes have a significant impact on the grid generators and complex switching operations; while DC short-circuit schemes require additional DC de-icing equipment, resulting in a larger investment. Summary of the Invention

[0004] This disclosure provides a medium-voltage flexible interconnection system, ice-melting method, and system with ice-melting function, which can realize interconnection and energy interaction between different power grid areas, has the ability to independently melt ice on distribution lines, does not require additional line ice-melting devices, is simple to operate, and effectively reduces distribution network investment.

[0005] In a first aspect, this disclosure provides a medium-voltage flexible interconnection system with de-icing function, comprising: multiple power electronic transformers, each power electronic transformer having an AC input terminal and a DC output terminal; the AC input terminals of the multiple power electronic transformers are respectively connected to multiple power grids, and the DC output terminals of the multiple power electronic transformers are connected to the same DC bus; the power electronic transformers are used to convert AC power from the power grids into DC power; each power electronic transformer includes multiple converter groups, each power electronic transformer having a working mode and a de-icing mode; in the working mode, multiple first converters connected to the AC input terminals of the multiple converter groups are connected in series, and the three-phase output lines of multiple second converters connected to the DC output terminals of the multiple converter groups are connected in parallel; in the de-icing mode, the multiple first converters connected to the AC input terminals of the multiple converter groups are connected in parallel, and the three-phase output lines of the multiple second converters connected to the DC output terminals of the multiple converter groups are short-circuited;

[0006] Energy storage devices are connected to the DC bus;

[0007] The controller is configured to, in response to a distribution line connected to the power grid by one of the power electronic transformers meeting the de-icing conditions, control the power electronic transformer to switch to de-icing mode, and at least control the energy storage device to supply power to the power electronic transformer to de-ic the distribution line connected to the power grid by the power electronic transformer.

[0008] In some embodiments, the controller is configured to, in response to the other power electronic transformer's connection to the grid not meeting the de-icing conditions, control the other power electronic transformer to maintain its operating mode, and control the energy storage device and the other power electronic transformer to supply power to one of the power electronic transformers, so as to de-ic the distribution line connected to the grid of the one power electronic transformer.

[0009] In some embodiments, the converter group further includes an isolation converter, through which the first converter is electrically connected to the second converter.

[0010] In some embodiments, the first converter is an AC / DC converter, and the second converter is an AC / DC converter;

[0011] The converter group further includes a third converter, through which the first converter is electrically connected to the isolation converter. The third converter is a DC / AC converter, and the isolation converter is used to reduce the AC voltage output by the third converter.

[0012] In some embodiments, the DC bus is also used for electrical connection with electrical equipment;

[0013] The controller is configured to control at least one of the plurality of power grids and the energy storage device to supply power to the electrical equipment through the DC bus.

[0014] In some embodiments, the DC bus is also used to connect to power generation equipment;

[0015] The controller is configured to control at least one of the power generation equipment and the energy storage equipment to supply power to the power grid and / or the energy storage equipment through the DC bus.

[0016] Secondly, this disclosure provides a de-icing method for a medium-voltage flexible interconnection system, comprising: in response to a distribution network line connected to a power grid and one of the power electronic transformers meeting the de-icing conditions, controlling the one of the power electronic transformers to switch to a de-icing mode;

[0017] The energy storage device is controlled to supply power to at least one of the power electronic transformers in order to melt ice on the distribution network lines connecting the power electronic transformer to the power grid.

[0018] In some embodiments, it also includes:

[0019] In response to the fact that the distribution network line connected to the power grid of another power electronic transformer does not meet the de-icing conditions, the other power electronic transformer is controlled to maintain the working mode.

[0020] The control of at least the energy storage device to supply power to one of the power electronic transformers includes:

[0021] The energy storage device and the other power electronic transformer are controlled to supply power to one of the power electronic transformers in order to melt ice on the distribution network line connecting the one of the power electronic transformers to the power grid.

[0022] In some embodiments, at least one of the plurality of power grids and the energy storage device is controlled to supply power to an electrical device via the DC bus, the electrical device being electrically connected to the DC bus.

[0023] In some embodiments, it also includes:

[0024] The system controls at least one of the power generation equipment and the energy storage equipment to supply power to the power grid and / or the energy storage equipment through the DC bus, wherein the power generation equipment is electrically connected to the DC bus.

[0025] Thirdly, this disclosure provides a power grid system including multiple power grids and the medium-voltage flexible interconnection system described above.

[0026] This disclosure provides a medium-voltage flexible interconnection system, de-icing method, and system with de-icing function. The flexible interconnection system includes multiple power electronic transformers, each with an AC input terminal and a DC output terminal. The AC input terminals of the multiple power electronic transformers are respectively connected to multiple power grids, and the DC output terminals of the multiple power electronic transformers are connected to the same DC bus. The power electronic transformers are used to convert AC power from the power grids to DC power. Each power electronic transformer includes multiple converter groups, comprising a working mode and a de-icing mode. In the working mode, multiple first converters connected to the AC input terminals of the multiple converter groups are connected in series, and the multiple converters... The three-phase output lines of multiple second converters connected to the DC output terminal of the power transformer group are in parallel; in the de-icing mode, multiple first converters connected to the AC input terminal of the multiple converter groups are connected in parallel, and the three-phase output lines of multiple second converters connected to the DC output terminal of the multiple converter groups are short-circuited; an energy storage device is connected to the DC bus; a controller is configured to control one of the power electronic transformers to switch to de-icing mode in response to one of the power electronic transformers' grid-connected distribution network lines meeting the de-icing conditions, and to at least control the energy storage device to supply power to the one of the power electronic transformers to de-ic the grid-connected distribution network lines of the one of the power electronic transformers. By configuring power electronic transformers, each of the two distribution networks can convert AC to DC through a power electronic transformer, and achieve energy exchange through the DC bus. This allows for flexible adjustment of transmission direction and efficiency, facilitating better control of the grid operation. During short-circuit de-icing, when one side of the distribution network is iced and needs to be shut down, the power electronic transformer on the opposite side operates in normal mode, with the AC / DC converter on the AC side connected in series. The opposite distribution network and energy storage device simultaneously increase power to supply the power electronic transformer on the iced side to operate in de-icing mode. When both distribution networks are iced and need to be shut down, both power electronic transformers operate in de-icing mode. At this time, the energy storage device provides the power required for de-icing, thus enabling independent de-icing of distribution lines without the need for additional line de-icing devices. This simplifies operation and effectively reduces distribution network investment. In addition, by connecting the DC bus to electrical equipment, such as car charging systems, different power grids can be connected, improving the efficiency of power resource utilization. At the same time, it can also provide backup power in emergency situations, improving the grid's anti-interference and resilience. It can connect to and support various power sources and energy storage devices, which helps to balance grid load and optimize energy structure. Attached Figure Description

[0027] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0028] Figure 1This is an exemplary connection relationship block diagram of a medium-voltage flexible interconnection system with ice-melting function provided in an embodiment of this disclosure;

[0029] Figure 2 An exemplary circuit structure diagram of the normal operation mode of the medium-voltage flexible interconnection system provided in the embodiments of this disclosure;

[0030] Figure 3 An exemplary circuit structure diagram of the short-circuit de-icing mode of the medium-voltage flexible interconnection system provided in this embodiment of the disclosure;

[0031] Figure 4 A schematic flowchart illustrating an exemplary ice-melting method provided in this disclosure embodiment;

[0032] Figure 5 A further exemplary process diagram of the ice-melting method provided in the embodiments of this disclosure;

[0033] Figure 6 This is a schematic block diagram of an electronic device provided in an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of a computer-readable storage medium provided in an embodiment of the invention.

[0035] In the accompanying drawings, the same parts are referred to by the same reference numerals, and the drawings are not drawn to scale. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions of this disclosure, and to fully understand and implement the process of how this disclosure applies technical means to solve technical problems and achieve corresponding technical effects, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. The embodiments of this disclosure and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort should fall within the protection scope of this disclosure.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure 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 disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover 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.

[0038] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0039] Medium-voltage flexible interconnection systems primarily refer to the flexible interconnection of medium-voltage power distribution networks on the feeder side, enabling the distribution network to have stronger power supply architecture adjustment capabilities and higher power supply reliability. Flexible interconnection devices can achieve intelligent interaction of power and energy between different power supply sections, realizing flexible cross-regional dispatching between different or equal voltage levels in asynchronous grids. This effectively improves the power transmission efficiency of distributed power sources, further enhancing system energy efficiency; simultaneously, it can avoid stability issues such as overvoltage caused by transformer power backflow. It allows each distribution network or microgrid to fully utilize its own characteristics, achieving friendly access for distributed new energy sources, energy storage devices, electric vehicles, etc., further improving power quality. In its control strategy, flexible interconnection considers AC / DC coupling characteristics and continuously changing operating states, enabling it to cope with complex and variable grid environments. Overall, medium-voltage flexible interconnection systems fully consider the characteristics and needs of the power system, with its main goal being to improve the flexibility and security of the power system, meeting diverse power demands and changes in its operating environment.

[0040] When the air temperature near the ground is below freezing, but the air temperature at higher altitudes is above freezing, raindrops falling on power transmission lines will form an ice layer on them. Ice accumulation significantly increases the weight of the transmission lines, causing additional mechanical stress on the lines and transmission towers. If the ice buildup is too heavy, it may cause the transmission lines to break or the transmission towers to collapse, resulting in power outages and costly repairs. Therefore, de-icing transmission lines is a crucial measure to ensure reliable power grid operation, prevent power system failures, and protect the surrounding environment and public safety. Short-circuit de-icing is one method of de-icing transmission lines. Its core idea is to use the Joule heating effect of a large current to heat the conductors, melting the ice on the lines. This typically requires a large current supplied at a low voltage. Existing AC short-circuit de-icing schemes have a significant impact on the grid generators and complex switching operations; while DC short-circuit schemes require additional DC de-icing equipment, resulting in a larger investment.

[0041] This disclosure discloses a medium-voltage flexible interconnection system with de-icing capabilities. Firstly, it enables interconnection and energy exchange between different power grid areas, allowing access to photovoltaic, energy storage, and charging systems, thus improving the flexibility and reliability of the distribution network. Secondly, it has the ability to independently de-ic the distribution lines without requiring additional line de-icing devices, simplifying operation and effectively reducing distribution network investment.

[0042] Example 1

[0043] Figure 1 This is a schematic diagram of the structure of a medium-voltage flexible interconnection system with ice-melting function under normal operating conditions, provided as an embodiment of this disclosure. Figure 1 As shown, a medium-voltage flexible interconnection system with ice-melting function includes multiple power electronic transformers, energy storage devices, and controllers;

[0044] like Figure 2 As shown, where Figure 2 The solid-state transformer in this embodiment is the power electronic transformer that can convert AC to DC and realize energy exchange through the DC bus.

[0045] In this system, the AC input terminals of each power electronic transformer are connected to multiple power grids, and the DC output terminals of these transformers are connected to the same DC bus. The power electronic transformers convert AC power from the power grids to DC power and have both an operating mode and an ice-melting mode, which can be switched between. An energy storage device is connected to the DC bus. A controller is configured to, in response to a distribution network line connected to one of the power electronic transformers meeting ice-melting conditions, control one of the power electronic transformers to switch to ice-melting mode and, at least, control the energy storage device to supply power to one of the power electronic transformers to melt the ice on the distribution network line connected to that power electronic transformer.

[0046] By configuring a power electronic transformer, it is possible to achieve the following during ice melting: Figure 3 As shown, the distribution lines requiring de-icing can be short-circuited three-phase before the low-voltage transformer outlet. At this time, the AC / DC modules of the power electronic transformer switch from a series connection to a parallel connection to provide the low-voltage, high-current required for de-icing. The installed energy storage device supplies power to the de-icing mode, eliminating the need for additional equipment and consideration of the grid generator's operating status, making operation convenient. When both distribution networks are iced and require shutdown, both power electronic transformers operate in de-icing mode. The energy storage device can still provide the necessary power for de-icing, improving reliability. Furthermore, the energy storage device flexibly selects its operating state based on the load of the interconnected system and the output of the wind turbines (grid side), fully utilizing its peak-shaving and valley-filling functions.

[0047] like Figure 2 and Figure 3 As shown, specifically, the power electronic transformer includes multiple converter groups and includes a working mode and an ice-melting mode. In the working mode, multiple first converters connected to the AC input terminal of the multiple converter groups are connected in series, and the three-phase output lines of multiple second converters connected to the DC output terminal of the multiple converter groups are connected in parallel. In the ice-melting mode, multiple first converters connected to the AC input terminal of the multiple converter groups are connected in parallel, and the three-phase output lines of multiple second converters connected to the DC output terminal of the multiple converter groups are short-circuited. By controlling the switching of the connection state of the multiple first converters connected to the AC input terminal of the multiple converter groups of the power electronic transformer, i.e., the switching between series and parallel connections, the power electronic transformer can switch between the working mode and the ice-melting mode, flexibly adjust the transmission direction and transmission power, and provide better control over the grid operation. Moreover, no additional equipment is required during short-circuit ice-melting, and the operating status of the grid generators does not need to be considered, making operation convenient.

[0048] Furthermore, such as Figure 2 and Figure 3As shown, the converter group also includes an isolation converter. The first converter is electrically connected to the second converter through the isolation converter. That is, the power electronic transformer adopts a solid-state transformer, integrating electrical isolation, voltage transformation, and reactive power compensation functions. Specifically, the first converter is an AC / DC converter, and the second converter is an AC / DC converter. The converter group also includes a third converter. The first converter is electrically connected to the isolation converter through the third converter. The third converter is a DC / AC converter, and the isolation converter is used to reduce the AC voltage output by the third converter. In the normal operating mode of the power electronic transformer, the 10kV medium-voltage power frequency AC power from both ends of the grid is connected to multiple AC / DC converters in series, and after conversion, it is converted into DC power. Then, it is converted into high-frequency AC power by the DC / AC converter. The voltage is further reduced by the high-frequency transformer, while achieving high- and low-voltage electrical isolation. Finally, it is converted into low-voltage DC power with adjustable output voltage by the AC / DC converter. All branches connected in the three phases are output in parallel, so that the power on both sides can be collected at the low-voltage DC bus, realizing energy retention between the two grids.

[0049] The bidirectional operation of the power electronic transformer allows it to supply power from the AC side to the DC side, and vice versa. Combined with photovoltaic power generation and energy storage devices connected to the low-voltage bus, it can fully utilize new energy sources and achieve flexible, multi-directional energy flow. When the load on one side of the grid increases, the opposite grid and energy storage devices can provide power support, making its use more flexible and facilitating grid operation control.

[0050] In some embodiments, the controller is also configured to, in response to a distribution network line connected to the power grid by another power electronic transformer not meeting the de-icing conditions, control another power electronic transformer to maintain its operating mode, and control the energy storage device and the other power electronic transformer to supply power to one of the power electronic transformers to de-ic the distribution network line connected to the power grid by the one power electronic transformer. By using the controller to control the switching of the operating modes of each power electronic transformer, flexible control can be achieved in combination with the lines requiring de-icing, improving the convenience of operation and use.

[0051] In this embodiment, the interconnection system can connect different power grids, improving the utilization efficiency of power resources. It can also provide backup power in emergency situations, enhancing the grid's anti-interference and resilience. Specifically, the DC bus is also used for electrical connection with electrical equipment; the controller is configured to control at least one of the multiple power grids and the energy storage device to supply power to the electrical equipment through the DC bus.

[0052] Among them, the electrical equipment can be a car charging system, i.e., a charging pile, or other electrical equipment, in order to improve the utilization rate of power resources.

[0053] Furthermore, the DC bus is also used to connect to the power generation equipment; the controller is configured to control at least one of the power generation equipment and the energy storage equipment to supply power to the power grid and / or the energy storage equipment through the DC bus. In this embodiment, the power generation equipment includes one or both of photovoltaic power generation and wind power generation, or other power generation equipment with power generation capabilities, thereby effectively improving the absorption capacity of new energy sources, flexibly selecting operating states, and fully leveraging the peak shaving and valley filling functions.

[0054] The medium-voltage flexible interconnection system provided in this embodiment, by configuring power electronic transformers, allows each of the two distribution networks to convert AC to DC through a power electronic transformer, and achieve energy exchange through the DC bus. This enables flexible adjustment of transmission direction and efficiency, facilitating better control of the grid operation. During short-circuit de-icing, when one side of the distribution network is iced and needs to be shut down, the power electronic transformer on the opposite side operates in normal mode with the AC / DC converter on the AC side connected in series. The opposite distribution network and the energy storage device simultaneously increase the power supply to the power electronic transformer on the iced side to operate in de-icing mode. When both distribution networks are iced and need to be shut down, both power electronic transformers operate in de-icing mode. At this time, the energy storage device provides the power required for de-icing, thus enabling independent de-icing of distribution lines without the need for additional line de-icing devices. This simplifies operation and effectively reduces distribution network investment. In addition, by connecting the DC bus to electrical equipment, such as car charging systems, different power grids can be connected, improving the efficiency of power resource utilization. At the same time, it can also provide backup power in emergency situations, improving the grid's anti-interference and resilience. It can connect to and support various power sources and energy storage devices, which helps to balance grid load and optimize energy structure.

[0055] Example 2

[0056] Based on the above embodiments, this embodiment provides a de-icing method for the medium-voltage flexible interconnection system described in Embodiment 1, such as... Figure 4 As shown, the method includes S1-S2, specifically:

[0057] S1. In response to the fact that the distribution network line connected to one of the power electronic transformers meets the de-icing conditions, control one of the power electronic transformers to switch to de-icing mode.

[0058] In some embodiments, the power electronic transformer includes an operating mode and an ice-melting mode. In the operating mode, multiple first converters connected to the AC input terminal of the multiple converter groups are connected in series, and the three-phase output lines of multiple second converters connected to the DC output terminal of the multiple converter groups are connected in parallel. In the ice-melting mode, multiple first converters connected to the AC input terminal of the multiple converter groups are connected in parallel, and the three-phase output lines of multiple second converters connected to the DC output terminal of the multiple converter groups are short-circuited. By controlling the power electronic transformers on the line to switch from series connection to parallel connection based on the response information, thus forming a short circuit and switching to the ice-melting mode for ice melting, no additional equipment is required, and the operating status of the grid generators does not need to be considered, making the operation convenient.

[0059] S2. Control the energy storage device to supply power to at least one of the power electronic transformers in order to melt ice on the distribution network line connecting the power electronic transformer to the power grid.

[0060] In some embodiments, with the cooperation of energy storage devices, the operating state can be flexibly selected according to the load of the interconnected system and the output of the wind turbine (grid side), so as to give full play to the role of peak shaving and valley filling.

[0061] In some embodiments, controlling the energy storage device to supply power to one of the power electronic transformers includes: controlling the energy storage device and the other power electronic transformer to supply power to the one of the power electronic transformers in order to melt ice on the distribution network line connecting the one of the power electronic transformers to the power grid.

[0062] In some embodiments, such as Figure 5 As shown, the method further includes steps S3-S5, specifically:

[0063] S3. In response to the fact that the distribution network line connected to the power grid of another power electronic transformer does not meet the de-icing conditions, control the other power electronic transformer to maintain the working mode.

[0064] S4. Control at least one of the plurality of power grids and the energy storage device to supply power to the electrical device through the DC bus, wherein the electrical device is electrically connected to the DC bus.

[0065] In some embodiments, the interconnection system can connect different power grids, improve the utilization efficiency of power resources, and provide backup power in emergency situations, thereby improving the grid's anti-interference and resilience. By configuring electrical equipment, the interconnection system can connect to and support multiple power sources and energy storage devices, which helps to balance grid load and optimize the energy structure.

[0066] S5. Control at least one of the power generation equipment and the energy storage equipment to supply power to the power grid and / or the energy storage equipment through the DC bus, wherein the power generation equipment is electrically connected to the DC bus.

[0067] In some embodiments, by configuring the power generation equipment to be connected to the DC bus, the power transmission direction and power can be flexibly adjusted in conjunction with the power electronic transformer, resulting in better control over the grid operation and effectively improving the capacity to absorb new energy sources.

[0068] In some embodiments, the de-icing method can be implemented in software, hardware, firmware, or any combination thereof, and is loaded and executed by a processor in a device such as a mobile phone, tablet, laptop, desktop computer, or network server. This enables interconnection and energy interaction between different power grid areas, has the ability to independently de-ic the distribution lines, does not require additional line de-icing devices, is simple to operate, and effectively reduces investment in the distribution network.

[0069] Example 3

[0070] Based on the above embodiments, this embodiment provides a power grid system, including multiple power grids and the medium-voltage flexible interconnection system described in Embodiment 1.

[0071] Example 4

[0072] Based on the above embodiments, this embodiment provides an electronic device, such as... Figure 6 As shown, the system includes a memory 21, a processor 22, and a computer program stored on the memory 21. The processor 22 executes the computer program to implement the steps of the method described in the above embodiments.

[0073] In some embodiments of this example, a computer-readable storage medium is provided, such as... Figure 7 As shown, a computer program 31 is stored thereon, which, when executed by a processor, implements the steps of the method described in the above embodiments.

[0074] In some embodiments of this example, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of the method described in the above embodiments.

[0075] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic component, for executing the methods described in the above embodiments.

[0076] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, and computer storage media (e.g., hard disks, floppy disks, solid-state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.).

[0077] Computer-readable storage media may also store at least one computer-executable program, such as computer-readable instructions. Computer-readable storage media include, but are not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Computer-readable storage media may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions stored on the computer-readable storage medium, the various methods described above can be performed.

[0078] In addition, the computer device may include (but is not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (e.g., keyboard, mouse, speakers, etc.).

[0079] The processor can communicate with external devices via the I / O bus through wired or wireless networks.

[0080] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product / computer program product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0081] In the embodiments provided in this disclosure, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0082] It should be noted that, in this disclosure, 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 limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0083] While the embodiments disclosed herein are as described above, the foregoing content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art to which this disclosure pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope of this disclosure; however, the scope of patent protection of this disclosure shall still be determined by the scope defined in the appended claims.

Claims

1. A medium-voltage flexible interconnection system with ice-melting function, characterized in that, include: Multiple power electronic transformers, each including an AC input terminal and a DC output terminal, are provided. The AC input terminals of the multiple power electronic transformers are connected to multiple power grids, and the DC output terminals of the multiple power electronic transformers are connected to the same DC bus. The power electronic transformers are used to convert AC power from the power grids into DC power. Each power electronic transformer includes multiple converter groups, comprising a working mode and an ice-melting mode. In the working mode, multiple first converters connected to the AC input terminals of the multiple converter groups are connected in series, and the three-phase output lines of multiple second converters connected to the DC output terminals of the multiple converter groups are connected in parallel. In the ice-melting mode, the multiple first converters connected to the AC input terminals of the multiple converter groups are connected in parallel, and the three-phase output lines of the multiple second converters connected to the DC output terminals of the multiple converter groups are short-circuited. Energy storage devices are connected to the DC bus; The controller is configured to, in response to a distribution line connected to the power grid by one of the power electronic transformers meeting the de-icing conditions, control the power electronic transformer to switch to de-icing mode, and at least control the energy storage device to supply power to the power electronic transformer to de-ic the distribution line connected to the power grid by the power electronic transformer.

2. The medium-voltage flexible interconnection system according to claim 1, characterized in that, The controller is configured to, in response to the other power electronic transformer's connection to the grid not meeting the de-icing conditions, control the other power electronic transformer to maintain its operating mode, and control the energy storage device and the other power electronic transformer to supply power to one of the power electronic transformers to de-ic the distribution line connected to the grid of the one power electronic transformer.

3. The medium-voltage flexible interconnection system according to claim 1, characterized in that, The converter group further includes an isolation converter, through which the first converter is electrically connected to the second converter.

4. The medium-voltage flexible interconnection system according to claim 3, characterized in that, The first converter is an AC / DC converter, and the second converter is an AC / DC converter; The converter group further includes a third converter, through which the first converter is electrically connected to the isolation converter. The third converter is a DC / AC converter, and the isolation converter is used to reduce the AC voltage output by the third converter.

5. The medium-voltage flexible interconnection system according to any one of claims 1-4, characterized in that, The DC bus is also used for electrical connection with electrical equipment. The controller is configured to control at least one of the plurality of power grids and the energy storage device to supply power to the electrical equipment through the DC bus.

6. The medium-voltage flexible interconnection system according to any one of claims 1-4, characterized in that, The DC bus is also used to connect to power generation equipment; The controller is configured to control at least one of the power generation equipment and the energy storage equipment to supply power to the power grid and / or the energy storage equipment through the DC bus.

7. A method for de-icing a medium-voltage flexible interconnection system according to any one of claims 1-6, characterized in that, include: In response to the fact that the distribution network line connected to one of the power electronic transformers meets the de-icing conditions, the power electronic transformer is controlled to switch to de-icing mode. The energy storage device is controlled to supply power to at least one of the power electronic transformers in order to melt ice on the distribution network lines connecting the power electronic transformer to the power grid.

8. The ice-melting method according to claim 7, characterized in that, Also includes: In response to the fact that the distribution network line connected to the power grid of another power electronic transformer does not meet the de-icing conditions, the other power electronic transformer is controlled to maintain the working mode. The control of at least the energy storage device to supply power to one of the power electronic transformers includes: The energy storage device and the other power electronic transformer are controlled to supply power to one of the power electronic transformers in order to melt ice on the distribution network line connecting the one of the power electronic transformers to the power grid.

9. The ice-melting method according to claim 7 or 8, characterized in that, Also includes: Control at least one of the plurality of power grids and the energy storage device to supply power to the electrical device through the DC bus, wherein the electrical device is electrically connected to the DC bus.

10. The ice-melting method according to claim 7 or 8, characterized in that, Also includes: The system controls at least one of the power generation equipment and the energy storage equipment to supply power to the power grid and / or the energy storage equipment through the DC bus, wherein the power generation equipment is electrically connected to the DC bus.

11. A power grid system, characterized in that, It includes multiple power grids and the medium-voltage flexible interconnection system as described in any one of claims 1-6.

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