Transformer area flexible interconnection device and power grid system

Abstract

The utility model provides a transformer area flexible interconnection device and a power grid system, and belongs to the technical field of power grids. The transformer area flexible interconnection device comprises a first energy storage converter, a second energy storage converter, a first isolation transformer and a direct current switch, the direct current end of the first energy storage converter is connected with the direct current end of the second energy storage converter through the direct current switch; the alternating current end of the first energy storage converter is connected with the first end of the first isolation transformer, and the second end of the first isolation transformer is connected with the first transformer area; and the alternating current end of the second energy storage converter is connected with the second transformer area. According to the utility model, the two energy storage converters are arranged in a back-to-back manner, so that energy conversion between the two transformer areas can be realized, and meanwhile, the isolation transformer is adopted for isolation, so that isolation protection between the two transformer areas is realized, and energy scheduling can be safely carried out between the two transformer areas.

Description

Technical Field

[0001] The utility model relates to the technical field of power grids, in particular to a flexible interconnection device for a substation area and a power grid system. Background Art

[0002] As an important part of the power system, the distribution substation area has a direct impact on our production and life. Most provinces and cities in China adopt a radial design and operation mode for low-voltage substation areas. The power grid operation mode is simple and easy to implement substation area management, but it lacks flexibility and cannot realize load transfer between substation areas and optimal load distribution of substation areas. Therefore, when a fault occurs or maintenance is carried out on the distribution transformer or line in the substation area, all users in the entire substation area will have a power outage, and the power supply reliability is relatively low.

[0003] In the prior art, affected by the addition of distributed power sources, the difference in electricity consumption between residential areas and industrial areas, and seasonal loads, the problem of uneven load between substation areas in space and time becomes prominent. Therefore, how to achieve safe closed-loop operation of multiple power sources, economic distribution of loop network power flow, and reasonable consumption of distributed power sources has become an urgent problem to be solved in the operation of the distribution network. Summary of the Utility Model

[0004] The embodiment of the utility model provides a flexible interconnection device for a substation area and a power grid system to solve the problem that energy exchange cannot be carried out between different substation areas in the prior art, and the problem that the unevenness of load between substation areas in space and time becomes prominent.

[0005] In a first aspect, the embodiment of the utility model provides a flexible interconnection device for a substation area, including: a first energy storage converter, a second energy storage converter, a first isolation transformer, and a DC switch;

[0006] The DC end of the first energy storage converter is connected to the DC end of the second energy storage converter through the DC switch;

[0007] The AC end of the first energy storage converter is connected to the first end of the first isolation transformer, and the second end of the first isolation transformer is connected to the first substation area;

[0008] The AC end of the second energy storage converter is connected to the second substation area.

[0009] Optionally, the flexible interconnection device for the substation area further includes: a second isolation transformer;

[0010] The first end of the second isolation transformer is connected to the AC end of the second energy storage converter, and the second end of the second isolation transformer is connected to the second substation area.

[0011] Optionally, the flexible interconnection device for the substation area further includes: a first AC switch;

[0012] The second end of the first isolation transformer is connected to the first end of the first AC switch, and the second end of the first AC switch is connected to the first power distribution area.

[0013] Optionally, the flexible interconnection device for power distribution areas further includes: a first soft start resistor and a first soft start switch;

[0014] The first end of the first soft start resistor is respectively connected to the second end of the first isolation transformer and the first end of the first AC switch, and the second end of the first soft start resistor is connected to the second end of the first AC switch through the first soft start switch.

[0015] Optionally, the flexible interconnection device for power distribution areas further includes: a first surge protector;

[0016] The first surge protector is connected to the second end of the first AC switch.

[0017] Optionally, the flexible interconnection device for power distribution areas further includes: a second AC switch;

[0018] The first end of the second AC switch is connected to the AC end of the second energy storage converter, and the second end of the second AC switch is connected to the second power distribution area.

[0019] Optionally, the flexible interconnection device for power distribution areas further includes: a second surge protector;

[0020] The second surge protector is connected to the first end of the second AC switch.

[0021] Optionally, the DC end of the first energy storage converter includes: a first positive DC end and a first negative DC end; the DC end of the second energy storage converter includes: a second positive DC end and a second negative DC end; the DC switch is a double-pole double-throw switch;

[0022] The first positive DC end is connected to the second positive DC end through the first switch in the double-pole double-throw switch;

[0023] The first negative DC end is connected to the second negative DC end through the second switch in the double-pole double-throw switch.

[0024] Optionally, the flexible interconnection device for power distribution areas further includes: a capacitor bank;

[0025] The capacitor bank is connected across the first positive DC end and the first negative DC end.

[0026] In a second aspect, an embodiment of the present invention provides a power grid system, including the flexible interconnection device for power distribution areas provided in any one of the embodiments of the first aspect above.

[0027] An embodiment of the present utility model provides a flexible interconnection device for a power distribution area and a power grid system. The flexible interconnection device for the power distribution area includes: a first energy storage converter, a second energy storage converter, a first isolation transformer, and a DC switch; the DC terminal of the first energy storage converter is connected to the DC terminal of the second energy storage converter through the DC switch; the AC terminal of the first energy storage converter is connected to the first end of the first isolation transformer, and the second end of the first isolation transformer is connected to the first power distribution area; the AC terminal of the second energy storage converter is connected to the second power distribution area. In the embodiment of the present utility model, two energy storage converters are provided, and the two energy storage converters are arranged back-to-back to realize the energy conversion between the two power distribution areas; when the power of the second power distribution area is excessive and the power of the first power distribution area is insufficient, the first energy storage converter can be controlled to be in the inversion state and the second energy storage converter can be controlled to be in the rectification state to transmit the power of the second power distribution area to the first power distribution area; conversely, when the power of the first power distribution area is excessive and the power of the second power distribution area is insufficient, the first energy storage converter can be controlled to be in the rectification state and the second energy storage converter can be controlled to be in the inversion state to transmit the power of the first power distribution area to the second power distribution area, thereby realizing the energy transfer between the two power distribution areas. At the same time, an isolation transformer is provided for isolation protection to avoid mutual influence between the two power distribution areas, so that the energy scheduling between the two power distribution areas can be carried out safely. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 is a schematic structural diagram of a flexible interconnection device for a power distribution area provided by an embodiment of the present utility model;

[0030] Figure 2 is a schematic structural diagram of another flexible interconnection device for a power distribution area provided by an embodiment of the present utility model;

[0031] Figure 3 is a schematic structural diagram of still another flexible interconnection device for a power distribution area provided by an embodiment of the present utility model. Detailed Embodiments

[0032] In order to enable those skilled in the art to better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution with reference to the drawings in the embodiments of this solution. Obviously, the described embodiments are some, but not all, of the embodiments of this solution. Based on the embodiments in this solution, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this solution.

[0033] In the description and claims of this solution and the above-mentioned drawings, the term "including" and any other variations thereof mean "including but not limited to", intending to cover non-exclusive inclusion and not limited only to the examples listed in the text. In addition, terms such as "first" and "second" are used to distinguish different objects rather than to describe a specific order.

[0034] The implementation of the present utility model will be described in detail below with reference to specific drawings:

[0035] With the widespread addition of new DC source loads such as distributed generation, distributed energy storage electric vehicles, etc., it has a greater impact on the traditional power grid. With the continuous advancement of the electrification process, the proportion of terminal electricity is continuously increasing, the terminal's requirement for power stability is also getting higher and higher, and with the increase in the power consumption load in the substation area, the access of distributed generation, energy storage, and impact loads such as charging piles, the difference in power consumption between residential areas and industrial areas, and seasonal loads, etc. will all lead to the imbalance of the load between substations in space and time. Therefore, it is necessary to reasonably dispatch the electric energy between different substations, relieve the load peak, balance the load, and improve the utilization rate of the remaining capacity.

[0036] Based on the above problems, referring to Figure 1 ,the embodiment of the present utility model provides a structural schematic diagram of a flexible interconnection device for substations. Referring to Figure 1 ,the flexible interconnection device for substations includes: a first energy storage converter 1, a second energy storage converter 2, a first isolation transformer 3, and a DC switch K1;

[0037] The DC terminal of the first energy storage converter 1 is connected to the DC terminal of the second energy storage converter 2 through the DC switch K1;

[0038] The AC terminal of the first energy storage converter 1 is connected to the first end of the first isolation transformer 3, and the second end of the first isolation transformer 3 is connected to the first substation area;

[0039] The AC terminal of the second energy storage converter 2 is connected to the second substation area.

[0040] The energy storage converter can achieve the conversion between bidirectional DC and AC. In the embodiment of the present utility model, two energy storage converters (the first energy storage converter 1 and the second energy storage converter 2) are provided. The two energy storage converters are arranged back-to-back, with the DC sides connected to each other, and the AC sides are respectively used to supply power to the first area and the second area. For example, when the second area needs to transfer electric energy to the first area, the DC switch K1 is closed. When the first energy storage converter 1 is in the inversion state and the second energy storage converter 2 is in the rectification state, the AC electric energy of the second area is rectified and inverted and then transferred to the first area; when the first area needs to transfer electric energy to the second area, the first energy storage converter 1 is in the rectification state and the second energy storage converter 2 is in the inversion state, and the AC electric energy of the first area is rectified and inverted and then transferred to the second area; when there is no need to transfer electric energy between the first area and the second area, the DC switch K1 is closed, and the path between the two areas is disconnected. At the same time, an isolation transformer is also provided in the path for isolation protection, so that the first area and the second area are relatively independent while transferring energy, without affecting their normal operations, avoiding the influence of the area flexible interconnection device on the first area and the second area, and improving the stability and reliability of the power grid operation.

[0041] In the embodiment of the present utility model, only two energy storage converters (the first energy storage converter 1 and the second energy storage converter 2) and one isolation transformer (the first isolation transformer 3) are adopted to realize the interconnection and mutual power supply between two areas, flexibly integrate and allocate electric power resources, effectively relieve the load peak, balance the load, effectively meet the demand during the peak electricity consumption period, improve the utilization rate of the remaining capacity, ensure the continuity and reliability of power supply through mutual support, and reduce the power outage risk caused by local overload. At the same time, with a certain control strategy, the area flexible interconnection device can reduce voltage fluctuations and frequency deviations, ensure more stable power supply quality, reduce line losses, reduce energy waste, and improve the energy efficiency of the entire power grid. It can also promote the access and utilization of renewable energy, more efficiently absorb and distribute these intermittent energy outputs, improve the utilization rate of renewable energy, and promote the green transformation of the energy structure.

[0042] It should be noted that the area flexible interconnection device also includes a controller, a monitoring device, a wireless communication device, etc., which are used to control the two converters and the DC switch K1, etc. Specifically, the controller can communicate with the power grid side electric energy meter in the Modbus-RTU protocol, read relevant power data in real time for adjustment, and can adjust the charge and discharge power of the two energy storage converters according to the power grid side power data on site to achieve energy scheduling between different areas. The specific control method is not limited to the above. This application only protects the hardware devices of the area flexible interconnection device, and the control method is not within the protection scope of this application.

[0043] Based on the above embodiments, a first isolation transformer 3 is provided at the rear end of the first energy storage converter 1. Although the isolation between the two power distribution areas is achieved, the connection between the first energy storage converter 1 and the second energy storage converter 2 and the second power distribution area may have a certain impact on the second power distribution area.

[0044] Based on the above, in a possible implementation, referring to Figure 2 , the flexible interconnection device for power distribution areas may further include: a second isolation transformer 4;

[0045] The first end of the second isolation transformer 4 is connected to the AC end of the second energy storage converter 2, and the second end of the second isolation transformer 4 is connected to the second power distribution area.

[0046] In the embodiment of the present utility model, a second isolation transformer 4 may also be provided at the rear end of the second energy storage converter 2 to isolate the second energy storage converter 2 from the second power distribution area, effectively avoiding the influence of the first energy storage converter 1 and the second energy storage converter 2 on the second power distribution area, strictly realizing the isolation between the first power distribution area and the second power distribution area, and the isolation between the flexible interconnection device for power distribution areas and the first power distribution area and the second power distribution area, effectively improving the stability of the power grid system.

[0047] In a possible implementation, referring to Figure 3 , the flexible interconnection device for power distribution areas may further include: a first AC switch K2;

[0048] The second end of the first isolation transformer 3 is connected to the first end of the first AC switch K2, and the second end of the first AC switch K2 is connected to the first power distribution area.

[0049] In the embodiment of the present utility model, a first AC switch K2 may also be provided to control the connection between the flexible interconnection device for power distribution areas and the first power distribution area.

[0050] In a possible implementation, referring to Figure 3 , the flexible interconnection device for power distribution areas may further include: a first soft start resistor R3 and a first soft start switch K4;

[0051] The first end of the first soft start resistor R3 is respectively connected to the second end of the first isolation transformer 3 and the first end of the first AC switch K2, and the second end of the first soft start resistor R3 is connected to the second end of the first AC switch K2 through the first soft start switch K4.

[0052] When the flexible interconnection device of the power distribution area starts up, a large current may be generated. Therefore, in the embodiment of the present utility model, a first soft start resistor R3 is provided. When starting up, the first soft start switch K4 is controlled to close, and the first AC switch K2 is opened. The first soft start resistor R3 is connected to perform soft start, limit the current impact, smooth the start-up process, protect the power distribution area equipment and the flexible interconnection device of the power distribution area, and improve the safety and stability of the flexible interconnection device of the power distribution area. After the soft start is completed, the first soft start switch K4 is opened, and the first AC switch K2 is closed to avoid unnecessary energy consumption caused by the first soft start resistor R3.

[0053] In a possible implementation manner, referring to Figure 3 , the flexible interconnection device of the power distribution area may further include: a first surge protector 5;

[0054] The first surge protector 5 is connected to the second end of the first AC switch K2.

[0055] When a spike current or voltage suddenly occurs due to the interference of the first power distribution area, the first surge protector 5 can conduct and shunt in an extremely short time, thereby avoiding damage to the first isolation transformer 3, the first energy storage converter 1, etc. caused by the surge, and improving the safety and reliability of the flexible interconnection device of the power distribution area.

[0056] In a possible implementation manner, referring to Figure 3 , the flexible interconnection device of the power distribution area may further include: a second AC switch K3;

[0057] The first end of the second AC switch K3 is connected to the AC end of the second energy storage converter 2, and the second end of the second AC switch K3 is connected to the second power distribution area.

[0058] Similarly, the flexible interconnection device of the power distribution area is also provided with a second AC switch K3 for controlling the connection between the second power distribution area and the second energy storage converter 2.

[0059] In a possible implementation manner, referring to Figure 3 , the flexible interconnection device of the power distribution area may further include: a second surge protector 6;

[0060] The second surge protector 6 is connected to the first end of the second AC switch K3.

[0061] At one end corresponding to the second power distribution area, the flexible interconnection device of the power distribution area is also provided with a second surge protector 6 for preventing the interference of the second power distribution area on the flexible interconnection device of the power distribution area, and further improving the safety and reliability of the flexible interconnection device of the power distribution area.

[0062] More specifically, the second surge protector 6 may also be connected to the second end of the second AC switch K3, and the specific position is not limited.

[0063] In a possible implementation manner, referring toFigure 3 The DC terminals of the first energy storage converter 1 include a first positive DC terminal and a first negative DC terminal; the DC terminals of the second energy storage converter 2 include a second positive DC terminal and a second negative DC terminal; the DC switch K1 can be a double-pole double-throw switch;

[0064] The first positive DC terminal is connected to the second positive DC terminal through the first switch of the double-pole double-throw switch;

[0065] The first negative DC terminal is connected to the second negative DC terminal through the second switch of the double-pole double-throw switch.

[0066] Those skilled in the art should be clear that the DC terminals of the first energy storage converter 1 and the second energy storage converter 2 are distinguished between positive and negative. Therefore, the DC switch K1 can be a double-pole double-throw switch, and the first positive DC terminal and the second positive DC terminal, as well as the first negative DC terminal and the second negative DC terminal, are turned on and off simultaneously.

[0067] In a possible implementation manner, the flexible interconnection device of the power distribution area may further include a capacitor bank;

[0068] The capacitor bank is connected across the first positive DC terminal and the first negative DC terminal.

[0069] A capacitor bank is also provided between the first energy storage converter 1 and the second energy storage converter 2 for filtering, which improves the stability of the DC terminal voltages of the first energy storage converter 1 and the second energy storage converter 2, thereby improving the stability of the flexible interconnection device of the power distribution area.

[0070] It should be noted that referring to Figure 3 , the AC terminals of the first energy storage converter 1, the AC terminals of the second energy storage converter 2, and both ends of the first isolation transformer 3 are all three-phase. Therefore, the first soft start switch K4, the second AC switch K3, and the first AC switch K2 are all switch groups, including three switches respectively used to control the three-phase AC; the first soft start resistor R3 also includes three resistors respectively connected in the three-phase path; the first surge protector 5 and the second surge protector 6 are also both three-phase protectors respectively connected in the three-phase path. For specific reference, see Figure 3 , which will not be elaborated here.

[0071] Corresponding to the above embodiments, the embodiment of the present invention also provides a power grid system, including the flexible interconnection device of the power distribution area provided in any of the above embodiments, and having the advantages of the above flexible interconnection device of the power distribution area, which will not be elaborated here specifically.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible interconnection device for a station area, characterized in that: include: A first energy storage converter, a second energy storage converter, a first isolation transformer and a DC switch; The DC end of the first energy storage converter is connected to the DC end of the second energy storage converter via the DC switch; The AC end of the first energy storage converter is connected to the first end of the first isolation transformer, and the second end of the first isolation transformer is connected to the first station area; The AC end of the second energy storage converter is connected to the second substation.

2. The flexible interconnection device of the stage area according to claim 1, characterized in that: The station area flexible interconnection device also includes: a second isolation transformer; The first end of the second isolation transformer is connected to the AC end of the second energy storage converter, and the second end of the second isolation transformer is connected to the second stage area.

3. The flexible interconnection device of claim 1, characterized in that: The station area flexible interconnection device also includes: a first AC switch; The second end of the first isolation transformer is connected to the first end of the first AC switch, and the second end of the first AC switch is connected to the first stage.

4. The flexible interconnection device of the stage area according to claim 3, characterized in that: The station area flexible interconnection device also includes: a first soft-start resistor and a first soft-start switch; The first end of the first soft-start resistor is connected to the second end of the first isolation transformer and the first end of the first AC switch respectively, and the second end of the first soft-start resistor is connected to the second end of the first AC switch through the first soft-start switch.

5. The flexible interconnection device of the metro area according to claim 3, characterized in that: The station area flexible interconnection device also includes: a first surge protector; The first surge protector is connected to the second end of the first AC switch.

6. The flexible interconnection device of claim 1, characterized in that: The station area flexible interconnection device also includes: a second AC switch; A first end of the second AC switch is connected to an AC end of the second energy storage converter, and a second end of the second AC switch is connected to the second stage.

7. The flexible interconnection device of the metro area according to claim 6, characterized in that: The station area flexible interconnection device also includes: a second surge protector; The second surge protector is connected to the first end of the second AC switch.

8. The flexible interconnection device for mesa areas according to any one of claims 1 to 7, characterized in that: The DC end of the first energy storage converter includes: a first positive DC end and a first negative DC end; the DC end of the second energy storage converter includes: a second positive DC end and a second negative DC end; the DC switch is a double-pole double-throw switch; The first positive DC terminal is connected to the second positive DC terminal through a first switch in the double-pole double-throw switch; The first negative DC terminal is connected to the second negative DC terminal through a second switch in the double-pole double-throw switch.

9. The stage area flexible interconnection device according to claim 8, characterized in that: The station area flexible interconnection device also includes: a capacitor group; The capacitor group is connected between the first positive DC terminal and the first negative DC terminal.

10. A power grid system, characterized in that: It comprises the flexible interconnection device of the stage area as described in any one of claims 1 to 9.

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