CN109802422B - Flexible looped network interconnection device and system - Google Patents

Abstract

The invention discloses a flexible looped network interconnection device and a system, wherein the flexible looped network interconnection device comprises: a plurality of electric wire netting interchange port, at least one first flexible interconnection module and at least one second flexible interconnection module, interconnect between first flexible interconnection module and the flexible interconnection module of second, wherein, first flexible interconnection module parallel connection is in between two interchange ports, and first interconnection module includes: at least one first DC port and/or at least one first AC port; the flexible interconnection module of second series connection is between two interchange ports, and the flexible interconnection module of second includes: and the second direct current port or the second alternating current port realizes interconnection of flexible ring networks at each end of alternating current and bidirectional flow of tide, so that the flexible switching and control modes of the power distribution operation mode are flexible.

Description

A flexible ring network interconnection device and system

technical field

The invention relates to the technical field of electric power equipment, in particular to a flexible ring network interconnection device and system.

Background technique

The distribution network is located at the end of the power system, directly facing the power users, and undertakes the heavy responsibility of distributing electric energy and serving customers. At present, the construction of the distribution network is lagging behind and the structure is unreasonable. "Closed-loop design and open-loop operation" have limited control means, restricted the flexibility of distribution network operation control, and caused problems such as unbalanced feeder load and long power supply recovery time. On the other hand, the increase in the proportion of nonlinear and impact loads in the distribution network and the continuous increase in the penetration rate of new energy have put forward higher requirements for the guarantee means of the power quality and power supply reliability of the distribution network. The existing distribution network is facing huge challenges in many aspects, such as customization and diversification of electricity demand, large-scale access to distributed power sources, and complexity of power flow coordination and control. These problems cannot be effectively solved simultaneously by conventional control means such as conventional switches.

SUMMARY OF THE INVENTION

Therefore, the present invention provides a flexible ring network interconnection device and system, which overcomes the deficiencies in the prior art, such as power supply interruption and ring closing impact caused by the conventional switch switching operation.

In a first aspect, an embodiment of the present invention provides a flexible ring network interconnection device, including: a plurality of grid AC ports, at least one first flexible interconnection module and at least one second flexible interconnection module, the first flexible interconnection module and the first flexible interconnection module. Two flexible interconnection modules are interconnected, wherein the first flexible interconnection module is connected in parallel between the two AC ports of the power grid, and the first flexible interconnection module includes: at least one first DC port and/or at least one a first AC port; the second flexible interconnection module is connected in series between the two grid AC ports, and the second flexible interconnection module includes: a second DC port or a second AC port.

In an embodiment, the first DC port and the second DC port are used for direct interconnection, or connected to the DC bus, or connected to the DC bus through a series switch.

In one embodiment, the first AC port and the second AC port are used for direct interconnection, or connected to the AC bus, or connected to the AC bus through a series switch.

In one embodiment, the first flexible interconnection module includes a multi-port power electronic transformer, and the multi-port power electronic transformer includes: at least one first DC port and/or at least one first AC port.

In one embodiment, the second flexible interconnection module includes: a series transformer and a voltage source converter, one end of the primary winding of the series transformer is connected to an AC port, the other end is connected to another AC port, and the secondary winding is connected to an AC port. Voltage source inverter connection.

In one embodiment, the series transformer and the voltage source converter are directly connected or connected through a series switch.

In an embodiment, the second flexible interconnection module further includes: a bypass switch, which is connected in parallel to both ends of the primary side and/or the secondary side winding of the series transformer, and is used for short-circuit protection of the series transformer.

In a second aspect, the present invention provides a flexible ring network interconnection system, comprising: a distributed power source, a load, an energy storage device, and the flexible ring network interconnection device described in the first aspect, the first flexible interconnection module and the second flexible interconnection module The interconnection modules are respectively connected to the common bus; the distributed power source, the load and the energy storage device are connected to the common bus to realize power flow interconnection with each power grid.

The technical scheme of the present invention has the following advantages:

1. A flexible ring network interconnection device provided by the present invention includes: a plurality of grid AC ports, at least one first flexible interconnection module and at least one second flexible interconnection module, the first flexible interconnection module and the second flexible interconnection module. The first flexible can be a multi-port open power electronic transformer, including at least one first DC port and/or at least one first AC port connected in parallel between two grid AC ports, and the second flexible interconnection module It can include a series transformer T and a voltage source converter VSC, which are connected in series between the AC ports of the two power grids to realize flexible ring network interconnection at each end of the AC, bidirectional flow of power flow, and flexible switching of power distribution operation modes and flexible control methods.

2. A flexible ring network interconnection system provided by the present invention, by interconnecting or connecting the flexible interconnection modules in the flexible ring network interconnection device to the common bus, not only the flexible ring network at each end of the exchange is interconnected, the power is flexibly regulated, and the power flow flows in both directions. , each flexible interconnection module is connected to the common bus, which realizes the multi-channel power supply of the common bus and enhances the reliability of the power supply system; the common bus is connected to distributed power sources, loads, etc., to improve the penetration rate and absorption capacity of distributed power sources , to improve the economy and reliability of the distribution network.

Description of drawings

In order to illustrate the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

1 is a flowchart of an example of a flexible ring network interconnection device provided by an embodiment of the present invention;

2 is a flowchart of another example of a flexible ring network interconnection device provided by an embodiment of the present invention;

3 is a flowchart of another example of a flexible ring network interconnection device provided by an embodiment of the present invention;

4 is a flowchart of another specific example of a flexible ring network interconnection device provided by an embodiment of the present invention;

5 is a flowchart of another specific example of a flexible ring network interconnection device provided by an embodiment of the present invention;

6 is a flowchart of a specific example of a flexible ring network interconnection system provided by an embodiment of the present invention;

FIG. 7 is a flowchart of another specific example of a flexible ring network interconnection system provided by an embodiment of the present invention.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection connection, or integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two components, which can be a wireless connection or a wired connection connect. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

An embodiment of the present invention provides a flexible ring network interconnection device, as shown in FIG. 1 , including: a plurality of grid AC ports (two AC ports are used as an example in FIG. 1 , but not limited thereto), at least one first flexible The interconnection module 11 and at least one second flexible interconnection module 21, the first flexible interconnection device and the second flexible interconnection device are interconnected (Fig. 1 includes a first flexible interconnection module 11 and a second flexible interconnection module 22). For example, but not limited to), the first flexible interconnection module is connected in parallel between the AC ports of the two power grids, and the first flexible interconnection module includes: at least one first DC port and/or at least one first an AC port; the second flexible interconnection module is connected in series between the AC ports of the two power grids, and the second flexible interconnection module includes: a second DC port or a second AC port.

In practical applications, the first DC port and the second DC port are used for direct interconnection, or are connected to the DC bus, or are connected to the DC bus through a series switch. The first AC port and the second AC port are used for direct interconnection, or connected to the AC bus, or connected to the AC bus through a series switch. In practical applications, the first DC port corresponding to the voltage property of the voltage level is interconnected with the second DC port, and the first AC port corresponding to the voltage property of the voltage level is interconnected with the second AC port.

The flexible ring network interconnection device provided by the embodiment of the present invention replaces the method of the feeder tie switch in the multi-segment-multi-connection distribution network adopted in the prior art, and can adjust the power flow between the connected feeders in real time according to the control command, In this way, the power flow distribution of the entire system is regulated, and the operation scheduling of the distribution network is more "flexible", with the characteristics of flexible switching of operation modes and flexible control methods.

In a specific embodiment, the flexible ring network interconnection device may include: four power grid AC ports, a first flexible interconnection module 11 and three second flexible interconnection modules 21 , as shown in FIG. 2 , the flexible ring network interconnection The device specifically includes: four AC ports are AC port 1, AC port 2, AC port 3, and AC port 4. All four AC ports can be medium voltage 10KV, which is only an example, not limited thereto. The AC port 1 and the AC port 2 are located on one feeder, the AC port 1 and the AC port 2 are located on the same feeder, and the two feeders are electrically interconnected. Wherein, the first flexible interconnection module 11 is connected in parallel between the AC port 1 and the AC port 2 through its AC port B1, and leads out the medium-voltage DC port B2 and the low-voltage AC port B3, and the three second flexible interconnection modules 21 respectively pass through the AC port B2 and the low-voltage AC port B3. The AC port C1 and the AC port C2 are connected in series between the AC port 1 and the AC port 2, and the low-voltage AC port C3 is drawn out, and the AC port C4 and the AC port C5 are connected in series between the AC port 3 and the AC port 4, and The low-voltage AC port C6 is led out, and the AC port C7 and the AC port C8 are connected in series between the AC port 3 and the AC port 4, and the low-voltage AC port C9 is led out, the above-mentioned low-voltage AC port B3, low-voltage AC port C3, low-voltage AC port Port C6 and low-voltage AC port C9 are directly interconnected.

In another specific embodiment, as shown in FIG. 3, the above-mentioned flexible ring network interconnection device directly connects the low-voltage AC port B3, the low-voltage AC port C3, the low-voltage AC port C6 and the low-voltage AC port C9 to the low-voltage DC bus or connects to the DC bus, or connect to the DC bus through a series switch.

In the embodiment of the present invention, the flexible ring network interconnection device shown in FIG. 2 or FIG. 3 directly interconnects or connects the low-voltage AC port B3, the low-voltage AC port C3, the low-voltage AC port C6, and the low-voltage AC port C9. The common DC busbar of corresponding voltage level realizes the interconnection of the AC system, the medium voltage DC system and the low voltage DC system, realizes the power flow balance of different lines, forms multiple energy paths, and forms a variety of energy flow directions and paths. Flexible control over power distribution.

In a specific embodiment, the first flexible interconnection module 11 includes a multi-port power electronic transformer, and the multi-port power electronic transformer includes: at least one first DC port and/or at least one first AC port, in the implementation of the present invention In the example, as shown in FIG. 4 , the first flexible interconnection module 11 is a three-port power electronic transformer, port B1 is a 10KV AC port, port B2 is a ±10KV DC port, port B3 is a ±375V DC port, and port B1 is connected to the AC port. 1. The port B2 is connected to the ±10KV DC bus, and the port B3 is connected to the ±375V DC bus. This is only an example, not limited thereto. In other embodiments, it can be a high-voltage DC port or the like.

In another specific embodiment, as shown in FIG. 5 , the first flexible interconnection module 11 is a three-port power electronic transformer, the port B1 is a 10KV AC port, the port B2 is a ±10KV DC port, and the port B3 is a 380V AC port, It can be connected to the AC bus 5 and connected to the AC port 1 through a transformer. The above is only an example, not limited thereto.

In a specific embodiment, as shown in FIG. 4 , the three second flexible interconnection modules 21 respectively include: a series transformer T and a voltage source converter VSC, forming a system including two 10KV AC ports and one ±375V DC port. Structure, wherein, port C1, port C2, port C4, port C5, port C7, port C8 are 10KV AC ports, and port C3, port C6, port C9 are ±375V DC ports. In the embodiment of the present invention, both ends of the primary and secondary windings of the series transformer T are connected across the bypass switch K (in other embodiments, the bypass switch K may be set on the primary or secondary windings) to connect the series transformer T For short-circuit protection, the bypass switch K is closed when the device is faulty, and disconnected when the device is working normally. One end of the primary winding is connected to a 10KV AC port, and the other end is connected to another 10KV AC port, corresponding to port C1 in Figure 3. Connect port 1 , port C2 is connected to port 2, port C4 is connected to port 3, port C5 is connected to port 1, port C7 is connected to port 1, and port C8 is connected to port 4; the secondary winding is connected in series with the AC side of the voltage source converter VSC; the voltage source commutation The connection between the DC side of the VSC and the first flexible interconnection module 11 and the ±375V DC bus corresponds to the connection of the ±375V DC bus to the ports C3, C6 and C9 in FIG. 3 .

In another embodiment, as shown in FIG. 5 , the second flexible interconnection module 21 further includes: an AC/DC link, which is connected to the voltage source converter VSC to convert direct current into alternating current, so that the second flexible interconnection module 21 can Interconnect module output AC port. The AC port of the first flexible interconnection module and the AC port of the second flexible interconnection module are connected to the AC bus bar 5, which is only an example and not limited thereto.

The flexible ring network interconnection device provided by the embodiment of the present invention includes: a plurality of grid AC ports, at least one first flexible interconnection module and at least one second flexible interconnection module, where the first flexibility may be a multi-port open power electronic transformer, including At least one first DC port and/or at least one first AC port is connected in parallel between the two grid AC ports, and the second flexible interconnection module may include a series transformer T and a voltage source converter VSC, which are connected in series to the two grids Between the AC and AC ports, the flexible ring network interconnection at each end of the AC is realized, and the power flow flows in both directions, which makes the power distribution operation mode switch flexibly and the control mode flexibly.

Example 2

An embodiment of the present invention further provides a flexible ring network interconnection system, as shown in FIG. 6 and FIG. 7 , the flexible ring network interconnection system includes: distributed power sources, loads, energy storage devices, and the flexible ring network described in Embodiment 1. In the network interconnection device, the first flexible interconnection module and the second flexible interconnection module are respectively connected to a common bus; distributed power sources and loads are connected to the common bus to realize power flow interconnection with each power grid.

In practical applications, the common bus can be a DC bus or an AC bus. When the common bus is a DC bus, the distributed power source can be, for example, a photovoltaic panel, the load can be a DC charging pile for electric vehicles, and the energy storage device can be The fixed energy storage device can also be a mobile energy storage device, such as a mobile energy storage vehicle, a mobile energy storage vehicle as a backup energy storage device, the DC energy storage converter of the energy storage device is a bidirectional converter, and an energy storage battery pack By connecting the DC energy storage converter to the DC bus, the DC energy storage converter can perform DC charging or DC discharging of the energy storage battery pack, and supply energy when the regulation capacity of the fixed energy storage device is insufficient; when the common bus is AC In the case of the bus, the distributed power source can be a wind power generation device, the AC load can be residential electricity, and the energy storage device can be a flywheel energy storage device. Similarly, the AC energy storage converter in the energy storage device is also a bidirectional converter. The flywheel energy storage device can be connected to the AC bus through the AC energy storage converter. The AC energy storage converter can perform AC charging or current discharge of the energy storage battery pack, and can carry out energy when the regulation capacity of the fixed energy storage device is insufficient. It ensures the reliability of power supply for important loads, improves the penetration rate and absorption capacity of distributed power sources, and improves the economy and reliability of the distribution network.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. And the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (6)

1. A flexible ring network interconnection device, comprising: a plurality of grid AC ports, at least one first flexible interconnection module and at least one second flexible interconnection module, the first flexible interconnection module and the second flexible interconnection The modules are interconnected, among which, The first flexible interconnection module is connected in parallel between the two AC ports of the power grid, and the first flexible interconnection module includes: at least one first DC port and/or at least one first AC port, the first flexible The interconnection module includes a multi-port power electronic transformer, and the multi-port power electronic transformer includes: at least one first DC port and/or at least one first AC port; The second flexible interconnection module is connected in series between the two AC ports of the power grid, the second flexible interconnection module includes: a second DC port or a second AC port, and the second flexible interconnection module includes: a series transformer and In the voltage source converter, one end of the primary winding of the series transformer is connected to an AC port, the other end is connected to another AC port, and the secondary winding is connected to the voltage source converter. 2 . The flexible ring network interconnection device according to claim 1 , wherein the first DC port and the second DC port are used for direct interconnection, or connected to a DC bus, or connected to a DC bus through a series switch. 3 . . 3 . The flexible ring network interconnection device according to claim 1 , wherein the first AC port and the second AC port are used for direct interconnection, or connected to the AC bus, or connected to the AC bus through a series switch. 4 . 4 . The flexible ring network interconnection device according to claim 1 , wherein the series transformer and the voltage source converter are directly connected or connected through a series switch. 5 . 5 . The flexible ring network interconnection device according to claim 4 , wherein the second flexible interconnection module further comprises: a bypass switch connected in parallel to both ends of the primary and/or secondary windings of the series transformer. 6 . , for short-circuit protection of the series transformer. 6. A flexible ring network interconnection system, characterized in that, comprising: a distributed power source, a load, an energy storage device and the flexible ring network interconnection device according to any one of claims 1-5, the first flexible interconnection module and the second flexible interconnection module are respectively connected to the common bus; The distributed power source, the load and the energy storage device are connected to the common bus, so as to realize power flow interconnection with each power grid.

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