Multi-port flexible interconnection system

Abstract

The utility model belongs to the technical field of comprehensive energy, and particularly discloses a multi-port flexible interconnection system which comprises at least three phase-shifting transformers and at least three groups of current-mode converters, each phase-shifting transformer is used as an input and output reference point of a port, each port is interconnected with other ports, and the current-mode converters are connected with the current-mode converters. A back-to-back converter composed of current type converters is used for interconnection of the two ports, and therefore flexible dispatching of electric energy among the at least three ports is achieved. According to the flexible interconnection system, multiple ports can be interconnected, flexible scheduling of electric energy of the multiple ports is achieved, the use range of the two ports is optimized, and the application scene of the flexible interconnection system is further widened.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of comprehensive energy, more specifically, relates to a multi-port flexible interconnection system. BACKGROUND

[0002] Traditional alternating current power grid has significant advantages in system stability and reliability, however, on the one hand, with the rapid development of economic society, the power load continues to increase, and the feeder load imbalance problem is prominent. The control ability of traditional distribution network shows deficiency, and cannot effectively solve the problems such as feeder congestion. Therefore, the actual operation capacity of the distribution network system is limited by the feeder with the capacity upper limit, which is often far lower than the design capacity of the distribution network, seriously affecting the economic operation of the distribution network.

[0003] On the other hand, developing renewable energy such as wind energy and solar energy has become a global consensus. As a distributed energy, wind energy and solar energy have the characteristics of intermittency, uncertainty and volatility, and when connected to the grid, they can exacerbate voltage out-of-limit, bidirectional flow and other problems, bringing serious technical challenges to the distribution network in voltage control, transient stability, oscillation damping and other aspects.

[0004] The mainstream flexible interconnection device at present is a back-to-back converter composed of two-port and voltage type converter, which can realize multi-directional power flow operation and decoupling control of active power and reactive power. However, most of the traditional flexible interconnection systems are two-port systems, which cannot realize the cooperation of more ports. CONTENT OF THE INVENTION

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a multi-port flexible interconnection system, which aims to solve the problem that most of the traditional flexible interconnection systems are two-port systems and cannot realize the cooperation of more ports.

[0006] To achieve the above-mentioned purpose, the present application provides a multi-port flexible interconnection system, comprising:

[0007] At least three phase-shift transformers and at least three groups of current type converters;

[0008] Each of the phase-shift transformers is an input and output reference point of a port, and a group of the current type converters is connected between any two of the phase-shift transformers;

[0009] The phase-shift transformers are used to reduce the harmonic content of the circuit and output a voltage level suitable for the normal operation of the current type converters, so as to cooperate with the current type converters to complete the flexible scheduling of different directions and different sizes of electric energy between different ports;

[0010] The current type converters are used to realize the flexible scheduling of different directions and different sizes of electric energy between different ports according to the control signals received thereby, and realize multi-port flexible interconnection.

[0011] In some embodiments, the current-type converter is composed of a rectifier, a smoothing reactor connected with the rectifier, and an inverter connected with the smoothing reactor.

[0012] In some embodiments, the smoothing reactor is a direct-current smoothing reactor.

[0013] In some embodiments, the smoothing reactor is a common-mode smoothing reactor.

[0014] In some embodiments, the phase-shifting transformer is a multi-pulse phase-shifting transformer.

[0015] In some embodiments, further comprising:

[0016] a plurality of electric energy meters, each of which is connected with one of the phase-shifting transformers, for recording electric energy data consumed by each port and uploading the electric energy data to an electric energy management system.

[0017] In some embodiments, the rectifier and the inverter are both three-phase bridge circuits composed of thyristors.

[0018] In some embodiments, the phase-shifting transformer and the current-type converter are connected through high-voltage cables or copper bars.

[0019] Overall, the above technical solutions conceived by the present application have at least the following beneficial effects compared with the prior art:

[0020] The multi-port flexible interconnection system provided by the present application includes at least three phase-shifting transformers and at least three groups of current-type converters, uses each phase-shifting transformer as an input and output reference point of a port, each port is interconnected with other ports, and the interconnection between two ports uses a "back-to-back" converter composed of a current-type converter, thereby realizing flexible scheduling of electric energy among at least three ports. Multiple ports can be interconnected to realize flexible scheduling of electric energy of multiple ports, optimize the use range of two-port, and further widen the application scenarios of the flexible interconnection system. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is one of the structural schematic diagrams of the multi-port flexible interconnection system provided by the embodiments of the present application;

[0022] Figure 2 is another of the structural schematic diagrams of the multi-port flexible interconnection system provided by the embodiments of the present application;

[0023] Figure 3 is a third of the structural schematic diagrams of the multi-port flexible interconnection system provided by the embodiments of the present application;

[0024] Figure 4is one of structure schematic diagram of current type converter between any two ports provided by the embodiment of the application;

[0025] Figure 5 is the second structure schematic diagram of current type converter between any two ports provided by the embodiment of the application;

[0026] Figure 6 is the structure schematic diagram of current type converter provided by the embodiment of the application.

[0027] In all the drawings, the same reference signs are used to indicate the same elements or structures, wherein 1 is a current type converter, 2 is a phase-shifting transformer, 3 is a high-voltage cable or copper bar, 4 is a rectifier, 5 is an inverter, 6 is a smoothing reactor, 7 is an electric energy meter, and 8 is a common-mode smoothing reactor. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0029] In the description of the utility model, it should be understood that the position description, such as the position or position relationship indicated by up, down, front, back, left and right, is based on the position or position relationship shown in the drawing, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as limiting the utility model.

[0030] In the description of the utility model, unless otherwise explicitly limited, the words such as setting, installing and connecting should be understood broadly, and the person skilled in the art can determine the specific meaning of the above words in the utility model in combination with the specific content of the technical scheme.

[0031] The multi-port flexible interconnection system provided by the embodiment of the application comprises a phase-shifting transformer, a rectifier, an inverter, a smoothing reactor, a high-voltage cable (or copper bar) and an electric energy meter, and is based on the function realized by the multi-port, wherein each phase-shifting transformer in the multi-port flexible interconnection system is used as the input and output reference point of the port, each port is interconnected with other ports, and the current type converter is used to realize the 'back-to-back' type converter, so as to realize the flexible scheduling of electric energy between multiple ports. In the embodiment of the application, the number of ports is at least three, for example, three ports, four ports and five ports and the like, which can satisfy various situations and make up for the deficiency of the single structure of two ports.

[0032] The embodiment of the application will be described below in combination with the drawings in the embodiment of the application.

[0033] Referring to Figure 1 , the embodiment of the present application provides a multi-port flexible interconnection system, comprising:

[0034] at least three phase-shifting transformers 2 and at least three groups of current-type converters 1;

[0035] each of the phase-shifting transformers 2 is an input and output reference point of a port, and a group of the current-type converters 1 is connected between any two of the phase-shifting transformers 2;

[0036] the phase-shifting transformers 2 are used to reduce the harmonic content of the circuit and output a voltage level suitable for normal operation of the current-type converters 1, so as to cooperate with the current-type converters 1 to complete flexible scheduling of different directions and different sizes of electric energy between different ports;

[0037] the current-type converters 1 are used to realize flexible scheduling of different directions and different sizes of electric energy between different ports according to the control signals received thereby, and realize multi-port flexible interconnection.

[0038] In the embodiment of the present application, the number of ports of the multi-port flexible interconnection system can be three ports, four ports and five ports, which correspond to Figure 1 , Figure 2 and Figure 3 respectively. In the embodiment of the present application, the number of ports of the multi-port flexible interconnection system can also be more ports, which is not limited in the present application.

[0039] As Figures 1 to 3 shown, the multi-port flexible interconnection system can comprise at least three phase-shifting transformers 2 and at least three groups of current-type converters 1. Each of the phase-shifting transformers 2 can be an input and output reference point of a port, and a group of the current-type converters 1 is connected between any two of the phase-shifting transformers 2, each group of the current-type converters 1 is composed of at least two current-type converters 1, and the functions realized by the multi-port flexible interconnection system composed of these configurations. Exemplarily, as Figure 4 shown, two current-type converters 1 are connected between any two of the phase-shifting transformers 2 to form a back-to-back converter.

[0040] The structure as Figure 4 shown makes the current-type converters 1 achieve bidirectional current flow, which is conducive to the control of the multi-port flexible interconnection system according to different situations and realizes flexible scheduling of electric energy between multiple ports.

[0041] The phase-shifting transformer 2 has the functions of reducing the harmonic content of the circuit and outputting a suitable voltage level for the normal operation of the current-type converter 1, so as to complete the flexible scheduling of the power in different directions and different sizes between different ports of the multi-port current-type converter 1. For example, the phase-shifting transformer 2 can be used to step down the high voltage in the power grid to obtain a range suitable for the long-term normal operation of the current-type converter 1.

[0042] Compared with the two-port flexible interconnection system, the multi-port flexible interconnection system provided in the application saves multiple phase-shifting transformers and current-type converters.

[0043] The current-type converter 1 can be used to realize the flexible scheduling of the power in different directions and different sizes between different ports according to the control signals received by the current-type converter 1, so as to realize the multi-port flexible interconnection.

[0044] The multi-port flexible interconnection system provided in the embodiments of the application not only can realize the flexible scheduling of the power, but also can increase the capacity of the phase-shifting transformer 2 of a certain port through interconnection, so as to realize the flexible interconnection of the system. Specifically, the multi-port flexible interconnection system can expand the capacity of the phase-shifting transformer of a certain port during operation, so that the transformer will not be damaged due to the load exceeding the capacity of the phase-shifting transformer.

[0045] The multi-port flexible interconnection system provided in the embodiments of the application can also interconnect multiple ports, so that the normal operation can be realized for a period of time when a certain port fails, and the cost loss caused by the failure can be reduced. Specifically, when the circuit between the phase-shifting transformer of a certain port of the multi-port flexible interconnection system and the load fails, the excess capacity of other ports can be distributed through flexible interconnection, so that the normal operation can be realized for a period of time, and great loss will not be caused due to the instantaneous failure of the phase-shifting transformer.

[0046] The multi-port flexible interconnection system provided in the embodiments of the application includes at least three phase-shifting transformers and at least three groups of current-type converters. Each phase-shifting transformer is used as an input and output reference point of a port, each port is interconnected with other ports, and the current-type converters are used to form a “back-to-back” converter for the interconnection of two ports, so as to realize the flexible scheduling of the power between at least three ports. Multiple ports can be interconnected to realize the flexible scheduling of the power of multiple ports, the use range of the two-port is optimized, and the application scenarios of the flexible interconnection system are further widened.

[0047] Further, in some embodiments, the phase-shifting transformer 2 is a multi-pulse phase-shifting transformer.

[0048] In order to solve the problem of large harmonic content of the traditional multi-port flexible interconnection system, a large number of devices are needed to reduce the harmonic, which causes waste of resources. In the embodiment of the application, the multi-pulse phase-shifting transformer is used as the phase-shifting transformer 2, so that the phase-shifting transformer 2 has the effect of reducing the harmonic content in the multi-port flexible interconnection system, and realizes the multi-loop output, and cooperates with the current type converter 1 to realize the multi-port flexible interconnection.

[0049] In the embodiment of the application, the multi-pulse phase-shifting transformer 2 can be a 6n-pulse phase-shifting transformer, wherein 6n is the pulse number, and the output end of the phase-shifting transformer 2 is an n-way output.

[0050] The multi-port flexible interconnection system provided by the embodiment of the application uses the multi-pulse phase-shifting transformer as the phase-shifting transformer, which can reduce the harmonic content of the transmission circuit, is conducive to harmonic suppression, and effectively improves the power quality in the process of power scheduling.

[0051] The voltage type converter used in the traditional multi-port flexible interconnection system causes huge power loss of the system, and some systems cannot even achieve the energy saving effect.

[0052] Further, in some embodiments, the current type converter 1 is composed of a rectifier 4, a smoothing reactor 6 connected with the rectifier 4, and an inverter 5 connected with the smoothing reactor 6.

[0053] Please further refer to Figure 4 , Figure 5 and Figure 6 In the embodiment of the application, the current type converter 1 can be specifically composed of a rectifier 4, an inverter 5 and a smoothing reactor 6.

[0054] One end of the rectifier 4 is connected with a phase-shifting transformer 2, the other end is connected with one end of the smoothing reactor 6, the other end of the smoothing reactor 6 is connected with the inverter 5, and the other end of the inverter 5 is connected with a phase-shifting transformer 2.

[0055] The rectifier 4 can be used to convert the alternating current in the power grid into direct current according to the received first control signal;

[0056] The smoothing reactor 6 can be used to remove the ripple in the direct current, so that the direct current output by the rectifier 4 becomes more flat, maintains continuity and smoothness, and effectively improves the power quality.

[0057] The inverter 5 can be used to convert the smoothing reactor 6 into alternating current according to the received second control signal.

[0058] The multi-port flexible interconnection system provided in the embodiments of the present application uses a rectifier, an inverter and a smoothing reactor to form a current type converter, which can effectively reduce the energy loss of the multi-port flexible interconnection system in energy scheduling, while maintaining the bidirectional flow function of the converter, and the use of the smoothing reactor can make the DC output by the rectifier more smooth, continuous and smooth, thereby effectively improving the power quality.

[0059] Further, in some embodiments, the smoothing reactor is a DC smoothing reactor.

[0060] In the embodiments of the present application, the smoothing reactor can be a DC smoothing reactor.

[0061] Further, in some embodiments, the smoothing reactor is a common mode smoothing reactor 8.

[0062] Please continue to see Figure 5 In the embodiments of the present application, the smoothing reactor can be a common mode smoothing reactor 8.

[0063] The common mode smoothing reactor 8 is also called a common mode choke coil, and is usually used in a switching power supply of an electronic device to filter common mode electromagnetic interference signals.

[0064] The common mode smoothing reactor 8 used in the prior art usually has coils wound on both sides of a magnetic core. When a working current flows through the coils, the magnetic fields generated by the coils cancel each other out. When a common mode current flows through the coils, due to the same directionality of the common mode current, the same direction magnetic field is generated in the coils to increase the inductance of the coils, so as to suppress the common mode current.

[0065] In the traditional multi-port flexible interconnection system, a large number of controller devices such as Insulate-Gate Bipolar Transistor (IGBT) are used, which causes high manufacturing cost of the system.

[0066] Further, in some embodiments, the rectifier 4 and the inverter 5 are both three-phase bridge circuits composed of thyristors.

[0067] In the embodiments of the present application, the rectifier 4 and the inverter 5 are both three-phase bridge circuits composed of thyristors, which further improves the reliability of the converter by using simple circuit structure and high-voltage and high-current components (thyristors).

[0068] The multi-port flexible interconnection system provided in the embodiments of the present application uses a rectifier and an inverter with a simple three-phase bridge circuit structure, and uses thyristors as the controller device. The combination of the simple structure and the reliable controller device effectively saves the manufacturing cost of the system and increases the reliability of the control.

[0069] Further, in some embodiments, the multi-port flexible interconnection system can further include:

[0070] a plurality of electric energy meters 7, each electric energy meter 7 being connected with one phase-shifting transformer 2, for recording electric energy data consumed by each port and uploading the electric energy data to an electric energy management system.

[0071] Please continue to see Figure 1 , Figure 2 and Figure 3 , the multi-port flexible interconnection system can further include a plurality of electric energy meters 7. Each electric energy meter 7 is connected with one phase-shifting transformer, which can be used to record electric energy data consumed by each port and upload the electric energy data to an electric energy management system. The uploaded electric energy data will be used in the control of the current-type converter 1, and at the same time, it will be used as an important evaluation support for the economic benefits of the multi-port flexible interconnection system.

[0072] Using the electric energy meter 7 to detect and transmit the electric energy flowing through each port, and transmitting the detected data to the electric energy management system, is beneficial for engineers to control and maintain the system, and can also know the energy-saving effect of the system in a certain period of time through the recorded data.

[0073] Further, in some embodiments, the phase-shifting transformer 2 is connected with the current-type converter 1 through a high-voltage cable 3 or a copper bar 3.

[0074] In the embodiments of the present application, the phase-shifting transformer 2 is connected with the current-type converter 1 through a high-voltage cable 3 or a copper bar 3.

[0075] As a preferred scheme of the embodiments of the present application, the selection of the high-voltage cable 3 or the copper bar 3 needs to be carefully considered. First, the voltage level and current level of the secondary side of the phase-shifting transformer 2 are considered, and a certain margin is left. Secondly, the position where the current-type converter 1 is placed is considered. The placement position will affect the length of the high-voltage cable 3 or the copper bar 3. When the length is too long, it will lead to an increase in cost.

[0076] The multi-port flexible interconnection system provided by the embodiments of the present application includes: a current-type converter 1, a phase-shifting transformer 2, a high-voltage cable 3 or a copper bar 3, a rectifier 4, an inverter 5, a smoothing reactor 6 and an electric energy meter 7. From the port, the electric energy meter 7 follows, and then the phase-shifting transformer 2 follows. The number of loops of the current-type converter 1 behind is determined according to the number of output loops of the phase-shifting transformer 2. The phase-shifting transformer 2 is connected with the current-type converter 1 using a high-voltage cable 3 or a copper bar 3. In the current-type converter 1, there are a rectifier 4 and an inverter 5, and a smoothing reactor 6 is used to connect between the rectifier 4 and the inverter 5.

[0077] As a preferred scheme of the embodiment of the present application, the selection of the phase-shifting transformer 2 needs to consider the voltage level and the required capacity of the grid port, and leave a certain margin to ensure some special cases of the multi-port flexible interconnection system.

[0078] As a preferred scheme of the embodiment of the present application, the selection of the thyristor constituting the current-type converter 1 needs to consider the voltage and current flowing through the current-type converter 1, and leave a margin of more than twice, while considering the rated switching times and service life of the thyristor, and the multi-port flexible interconnection system will be used for a long time, and the reliability of the multi-port flexible interconnection system needs to be ensured.

[0079] As a preferred scheme of the embodiment of the present application, the electric energy meter 7 needs to be installed at each port, and the electric energy data consumed by each port needs to be transmitted to the electric energy management system, and the electric energy data can be used to control the current-type converter 1 while saving the electric energy data.

[0080] It should be understood that expressions such as "include" and "may include" used in the present application indicate the presence of disclosed functions, operations or constituent elements, and do not limit one or more additional functions, operations and constituent elements. In the present application, terms such as "include" and / or "have" can be interpreted to mean that a specific feature, number, operation, constituent element, component or combination thereof is present, but cannot be interpreted to exclude the possibility of existence or addition of one or more other features, numbers, operations, constituent elements, components or combinations thereof.

[0081] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0082] In the description of the embodiment of the present application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, "connection" can be detachable connection, or can be non-detachable connection; can be direct connection, or can be indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative positional relationship after connection is unchanged. "Rotary connection" means that the relative rotation after connection is connected. "Sliding connection" means that the relative sliding after connection is connected. The orientation language mentioned in the embodiment of the present application, such as "top", "bottom", "inner", "outer", "left", "right", etc., is only the direction of the drawing, therefore, the orientation language used is to better, more clearly illustrate and understand the embodiment of the present application, and is not to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the embodiment of the present application.

[0083] In addition, in the embodiments of the present application, the mathematical concepts of symmetry, equality, parallel, perpendicular, etc. are mentioned. These limitations are for the current process level, not the absolute strict definition in the mathematical sense, and a small amount of deviation is allowed, such as approximately symmetrical, approximately equal, approximately parallel, approximately perpendicular, etc. For example, A is parallel to B, which means that A and B are parallel or approximately parallel, and the included angle between A and B can be between 0 degrees and 10 degrees. A is perpendicular to B, which means that A and B are perpendicular or approximately perpendicular, and the included angle between A and B can be between 80 degrees and 100 degrees.

[0084] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multi-port flexible interconnection system, characterized by, The application relates to a multi-port flexible interconnection system, comprising: at least three phase-shifting transformers and at least three groups of current-mode converters; each phase-shifting transformer is used as an input and output reference point of a port, and a group of current-mode converters is connected between any two phase-shifting transformers; the phase-shifting transformers are used for reducing the harmonic content of a circuit and outputting a voltage level suitable for the normal operation of the current-mode converters, so that the current-mode converters complete the flexible scheduling of the power in different directions and different sizes between different ports; the current-mode converters are used for realizing the flexible scheduling of the power in different directions and different sizes between different ports according to the control signals received by the current-mode converters, and realizing the multi-port flexible interconnection.

2. The multiport flexible interconnection system of claim 1, wherein, The current-mode converter is composed of a rectifier, a smoothing reactor connected with the rectifier and an inverter connected with the smoothing reactor.

3. The multiport flexible interconnection system of claim 2, wherein, The smoothing reactor is a direct-current smoothing reactor.

4. The multiport flexible interconnection system of claim 2, wherein, The smoothing reactor is a common-mode smoothing reactor.

5. The multiport flexible interconnection system of claim 1, wherein, The phase-shifting transformer is a multi-pulse phase-shifting transformer.

6. The multiport flexible interconnection system of claim 1, wherein, The application further comprises: a plurality of electric energy meters, each of which is connected with a phase-shifting transformer and is used for recording the electric energy data consumed by each port and uploading the electric energy data to an electric energy management system.

7. The multiport flexible interconnection system of claim 2, wherein, The rectifier and the inverter are both three-phase bridge circuits composed of thyristors.

8. The multiport flexible interconnection system of any of claims 1-7, wherein, The phase-shifting transformer and the current-mode converter are connected through high-voltage cables or copper bars.

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