CN113783197A

CN113783197A - Power distribution network flexible interconnection device and control method thereof

Info

Publication number: CN113783197A
Application number: CN202111239550.5A
Authority: CN
Inventors: 毕成; 肖风良; 李伟; 谢文刚; 宋中建; 张志成
Original assignee: Shandong Taikai Dc Technology Co ltd; Shandong Taikai High Volt Switchgear Co Ltd
Current assignee: Shandong Taikai Dc Technology Co ltd; Shandong Taikai High Volt Switchgear Co Ltd
Priority date: 2021-10-25
Filing date: 2021-10-25
Publication date: 2021-12-10

Abstract

The application discloses distribution network flexible interconnection device and control method thereof, and the distribution network flexible interconnection device comprises: the system comprises a plurality of AC/DC bidirectional converters, a plurality of control circuits and a plurality of control circuits, wherein DC ends of the AC/DC bidirectional converters are electrically connected, and AC ends of the AC/DC bidirectional converters are electrically connected with input ends; and mechanical interconnection switches are arranged in front of the two different groups of AC/DC bidirectional converters and are respectively connected with the AC ends of the AC/DC bidirectional converters in an electric connection mode. A flexible interconnection device consisting of an AC/DC bidirectional converter and a mechanical interconnection switch is integrated on the basis of the traditional interconnection switch of the power distribution network. The power flow between the bus and the feeder line when the distribution network normally operates is realized, the power of the bus of the transformer substation with lower load rate can be fully utilized, and the energy utilization rate is improved. When the flexible interconnection of the bus and the feeder line is realized, the addition of the mechanical interconnection switch can realize that once a fault line occurs, another normal operation line supplies power to a load in the fault line.

Description

Power distribution network flexible interconnection device and control method thereof

Technical Field

The application relates to the technical field of alternating current power distribution networks, in particular to a power distribution network flexible interconnection device and a control method thereof.

Background

With the diversification of power generation and utilization forms, the role of a power distribution network in a power system becomes more and more important. The high-efficiency consumption of various distributed new energy sources, the coordination and allocation of the energy sources, the high-quality supply at the user side and the like are all completed through a power distribution network, the power distribution network is directly connected with power users, and the power supply reliability of the power distribution network has great influence on the users. Statistics shows that 80% of user power failure accidents are caused by power distribution system faults, so that the method has very important practical significance for improving the operation reliability of the power distribution network.

The traditional power distribution network is limited by the problems of short circuit capacity, electromagnetic looped network and the like, and is forced to adopt a mode of closed-loop design and open-loop operation. The power supply system has the advantages that the power supply system is in a radial wiring form during normal operation, the tide direction is single, the protection mode is simple, although the operation and the management are convenient, the power supply reliability is relatively low, short-time power failure is needed for fault isolation and power supply recovery after a fault, and the power supply reliability is difficult to further improve. The power flow is naturally distributed along with the network structure parameters and the load requirements, and the power flow distribution can be changed to a certain extent only through the network reconstruction of the switch operation. Open loop operation has a negative impact on power supply reliability, and poor power flow control has a negative impact on safety and power supply capability.

The flexible multi-state switch can meet customized power requirements of intelligent power distribution network distributed energy consumption, high power supply reliability and the like, and is regarded as key power distribution equipment for improving power supply flexibility and reliability. Aiming at the current situation that urban and rural power distribution networks in China are weak in development, the application of the flexible multi-state switch technology is expected to improve the medium-voltage line contact rate, construct a strong load transfer channel, improve the power quality and the like. However, the large-capacity flexible switch has a complex structure and high manufacturing cost, and the application and popularization of the large-capacity flexible switch in the power distribution network are limited.

Disclosure of Invention

In order to solve the technical problems, the following technical scheme is provided:

in a first aspect, an embodiment of the present application provides a flexible interconnection device for a power distribution network, including: the system comprises a plurality of AC/DC bidirectional converters, a plurality of control circuits and a plurality of control circuits, wherein DC ends of the AC/DC bidirectional converters are electrically connected, and AC ends of the AC/DC bidirectional converters are electrically connected with input ends; and mechanical interconnection switches are arranged in front of the two different groups of AC/DC bidirectional converters and are respectively connected with the AC ends of the AC/DC bidirectional converters in an electric connection mode.

By adopting the implementation mode, the flexible interconnection device consisting of the AC/DC bidirectional converter and the mechanical interconnection switch is integrated on the basis of the traditional interconnection switch of the power distribution network. The power flow between the bus and the feeder line when the distribution network normally operates is realized, the power of the bus of the transformer substation with lower load rate can be fully utilized, and the energy utilization rate is improved. When the flexible interconnection of the bus and the feeder line is realized, the addition of the mechanical interconnection switch can realize that once a fault line occurs, another normal operation line supplies power to a load in the fault line.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the first input end is electrically connected to a first feeder line, the second input end is electrically connected to a second feeder line, the first feeder line and the second feeder line are feeder lines of a same bus of a same substation, and the first input end and the second input end are any two input ends among all input ends.

When the flexible interconnection device is arranged between different feeder lines of the same transformer substation and the same bus, taking two feeder lines as an example, the first feeder line is electrically connected with the input end of the first AC/DC bidirectional converter, and the second feeder line is electrically connected with the input end of the second AC/DC bidirectional converter. If the load rate of the first feeder line is low and the load of the second feeder line is high at a certain moment, the first AC/DC bidirectional converter and the second AC/DC bidirectional converter control power to flow from the end with low load power to the end with high load power, active support and reactive compensation are provided, and closed-loop operation and current control of two feeder lines of the same bus are achieved. In emergency, when one section of feeder line is in fault and power is cut off, the interconnection switch is switched on, and the other normally-operating feeder line supplies power to the load in the fault feeder line, so that the load pressures of different feeder lines of different buses are shared.

With reference to the first aspect, in a second possible implementation manner of the first aspect, the first input end is electrically connected to a third feeder line, the second input end is electrically connected to a fourth feeder line, the third feeder line and the fourth feeder line are feeder lines of different buses of the same substation, and the first input end and the second input end are any two input ends of all the input ends.

When the flexible interconnection device is arranged between different feeder lines of the same transformer substation and different buses, still taking two feeder lines as an example, the third feeder line is electrically connected with the input end of the first AC/DC bidirectional converter, and the fourth feeder line is electrically connected with the input end of the second AC/DC bidirectional converter. If the load rate of the third feeder line is low and the load of the fourth feeder line is high at a certain moment, the first AC/DC bidirectional converter and the second AC/DC bidirectional converter control the power to flow from the end with low load power to the end with high load power, active support and reactive compensation are provided, and closed-loop operation and current control of different feeder lines of different buses are realized. In emergency, when one section of feeder line is in fault and power failure, the interconnection switch is switched on, and the other normally-operating feeder line supplies power to the load in the fault feeder line, so that the load pressure between the feeder lines of different buses of the same transformer substation is shared.

With reference to the first aspect, in a third possible implementation manner of the first aspect, the first input end is electrically connected to the first bus, the second input end is electrically connected to the second bus, the first bus and the second bus are located in the same substation, and the first input end and the second input end are any two input ends among all the input ends.

When the flexible interconnection device is arranged between different buses of the same transformer substation, the two buses are taken as an example, the first bus is electrically connected with the input end of the first AC/DC bidirectional converter, and the second bus is electrically connected with the input end of the second AC/DC bidirectional converter. If the load rate of the first bus is low and the load of the second bus is high at a certain moment, the first AC/DC bidirectional converter and the second AC/DC bidirectional converter control power to flow from the end with low load power to the end with high load power, active support and reactive compensation are provided, and closed-loop operation and current control between different buses of the same transformer substation are achieved. In emergency, when one bus is in fault and power failure, the interconnection switch is switched on, and the other bus which normally runs supplies power to the load in the fault bus, so that the load pressure of the same transformer substation is shared.

With reference to the first aspect, in a fourth possible implementation manner of the first aspect, the first input end is electrically connected to the first bus, the second input end is electrically connected to the second bus, the first bus and the second bus are located in different substations, and the first input end and the second input end are any two input ends of all the input ends.

When the flexible interconnection device is arranged between different substations and different buses, the two buses are taken as an example, the third bus is electrically connected with the input end of the first AC/DC bidirectional converter, and the fourth bus is electrically connected with the input end of the second AC/DC bidirectional converter. If the load rate of the third bus is low and the load of the fourth bus is high at a certain moment, the first AC/DC bidirectional converter and the second AC/DC bidirectional converter control power to flow from the end with low load power to the end with high load power, active support and reactive compensation are provided, and closed-loop operation and current control of different substation buses are achieved. In emergency, when one bus is in fault and power failure, the interconnection switch is switched on, and the buses in normal operation of different transformer stations supply power to the load in the fault bus, so that the pressure of a transformer substation at the end of the fault bus is reduced.

With reference to the first aspect, in a fifth possible implementation manner of the first aspect, the first input end is electrically connected to a fifth feeder line, the second input end is electrically connected to a sixth feeder line, the fifth feeder line and the sixth feeder line are feeder lines of different busbars of different transformer substations, and the first input end and the second input end are any two input ends of all the input ends.

When the flexible interconnection device is arranged between different feeder lines of different substations and different buses, still taking two feeder lines as an example, the fifth feeder line is electrically connected with the input end of the first AC/DC bidirectional converter, and the sixth feeder line is electrically connected with the input end of the second AC/DC bidirectional converter. If the load rate of the fifth feeder line is low at a certain moment, and the load of the sixth feeder line is high, the first AC/DC bidirectional converter and the second AC/DC bidirectional converter control power to flow from the end with low load power to the end with high load power, active support and reactive compensation are provided, and closed-loop operation and tide flow control of different feeders of different buses of different transformer substations are realized. In emergency, when one section of feeder line is in fault and power is cut off, the interconnection switch is switched on, and the other normally-operating feeder line supplies power to a load in the fault feeder line, so that the pressure of a bus at the end of the fault feeder line is reduced.

With reference to the first aspect or any one of the first to the fifth possible implementation manners of the first aspect, in a sixth possible implementation manner of the first aspect, a direct current bus is disposed between adjacent AC/DC bidirectional converters, two ends of the direct current bus are respectively electrically connected to DC ends of different AC/DC bidirectional converters, and the direct current bus is connected to a new energy power supply. The new energy power supply comprises photovoltaic, energy storage and other new energy power supplies, and the new energy power supply is connected to supply power for various direct current loads, so that the diversity of system energy supply is increased, and the system reliability is improved.

With reference to the sixth possible implementation manner of the first aspect, in a seventh possible implementation manner of the first aspect, the mechanical interconnection switch is normally open in an initial state.

In a second aspect, an embodiment of the present application provides a method for controlling a flexible interconnection apparatus of a power distribution network, where the method is used to control the flexible interconnection apparatus of the power distribution network according to the first aspect or any possible implementation manner of the first aspect, and the method includes: judging the running state of the transformer substation; if the transformer substation normally operates, the mechanical interconnection switch is kept to be switched off, the AC/DC bidirectional converter realizes interconnection between a bus or a feeder of the power distribution network, and power flow is controlled; or if the substation runs abnormally, determining an abnormal bus or feeder line, and switching the lines through the mechanical interconnection switch.

With reference to the second aspect, in a first possible implementation manner of the second aspect, the line switching through the mechanical interconnection switch includes: and controlling a mechanical interconnection switch connected with the abnormal bus or the feeder line to be switched on, and replacing the abnormal bus or the feeder line with the bus or the feeder line electrically connected with the mechanical interconnection switch.

Drawings

Fig. 1 is a schematic structural diagram of a power distribution network flexible interconnection apparatus according to an embodiment of the present disclosure;

fig. 2 is a schematic diagram illustrating an arrangement of a power distribution network flexible interconnection apparatus according to an embodiment of the present application;

fig. 3 is a schematic diagram illustrating an arrangement of a power distribution network flexible interconnection apparatus according to an embodiment of the present application;

fig. 4 is a schematic diagram illustrating an arrangement of a power distribution network flexible interconnection apparatus according to an embodiment of the present application;

fig. 5 is a schematic diagram illustrating an arrangement of a power distribution network flexible interconnection apparatus according to an embodiment of the present application;

fig. 6 is a schematic diagram illustrating an arrangement of a power distribution network flexible interconnection apparatus according to an embodiment of the present application;

fig. 7 is a schematic diagram of a power distribution network flexible interconnection device connected to a new energy power supply according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of another power distribution network flexible interconnection apparatus provided in the embodiment of the present application;

fig. 9 is a schematic flowchart of a control method of a power distribution network flexible interconnection apparatus according to an embodiment of the present application.

Detailed Description

The present invention will be described with reference to the accompanying drawings and embodiments.

The flexible interconnection device of distribution network that this application embodiment provided includes: the system comprises a plurality of AC/DC bidirectional converters, a plurality of control circuits and a plurality of control circuits, wherein DC ends of the AC/DC bidirectional converters are electrically connected, and AC ends of the AC/DC bidirectional converters are electrically connected with input ends; and mechanical interconnection switches are arranged in front of the two different groups of AC/DC bidirectional converters and are respectively connected with the AC ends of the AC/DC bidirectional converters in an electric connection mode.

Fig. 1 is a schematic structural diagram of a flexible interconnection device of a power distribution network according to an embodiment of the present application, where the flexible interconnection device of the power distribution network in fig. 1 includes a first AC/DC bidirectional converter VSC1, a second AC/DC bidirectional converter VSC2, and a mechanical interconnection switch CS, and the mechanical interconnection switch CS is normally open at an initial state. The flexible interconnection device for the power distribution network provided in fig. 1 is taken as an example, and the flexible interconnection device for the power distribution network is applied to the same transformer substation and different transformer substations to be explained one by one.

Referring to fig. 2, a first input end is electrically connected to a first feeder line, a second input end is electrically connected to a second feeder line, the first feeder line and the second feeder line are feeder lines of the same bus of the same substation, and the first input end and the second input end are any two input ends among all the input ends.

The first feed line is electrically connected to the input of a first AC/DC bidirectional converter VSC1 and the second feed line is electrically connected to the input of a second AC/DC bidirectional converter VSC 2. If the load rate of the first feeder line is low and the load of the second feeder line is high at a certain moment, the first AC/DC bidirectional converter VSC1 and the second AC/DC bidirectional converter VSC2 control the power to flow from the end with the lower load power to the end with the higher load power, active support and reactive compensation are provided, and closed-loop operation and tide flow control of two feeder lines of the same bus are achieved. In emergency, when one section of feeder line is in fault and power is cut off, the interconnection switch is switched on, and the other normally-operating feeder line supplies power to the load in the fault feeder line, so that the load pressures of different feeder lines of different buses are shared.

Referring to fig. 3, the first input end is electrically connected to a third feeder line, the second input end is electrically connected to a fourth feeder line, the third feeder line and the fourth feeder line are feeder lines of different buses of the same substation, and the first input end and the second input end are any two input ends among all the input ends.

The third feed line is electrically connected to the input of a first AC/DC bi-directional converter VSC1 and the fourth feed line is electrically connected to the input of a second AC/DC bi-directional converter VSC 2. If the load factor of the third feeder line is low and the load of the fourth feeder line is high at a certain moment, the first AC/DC bidirectional converter VSC1 and the second AC/DC bidirectional converter VSC2 control the power to flow from the end with the lower load power to the end with the higher load power, active support and reactive compensation are provided, and closed-loop operation and tide flow control of different feeder lines of different buses are achieved. In emergency, when one section of feeder line is in fault and power failure, the interconnection switch is switched on, and the other normally-operating feeder line supplies power to the load in the fault feeder line, so that the load pressure between the feeder lines of different buses of the same transformer substation is shared.

Referring to fig. 4, a first input end is electrically connected to a first bus bar, a second input end is electrically connected to a second bus bar, the first bus bar and the second bus bar are located in the same substation, and the first input end and the second input end are any two input ends among all the input ends.

The first bus is electrically connected with the input of a first AC/DC bidirectional converter VSC1 and the second bus is electrically connected with the input of a second AC/DC bidirectional converter VSC 2. If the load rate of the first bus is low and the load of the second bus is high at a certain moment, the first AC/DC bidirectional converter VSC1 and the second AC/DC bidirectional converter VSC2 control the power to flow from the end with the lower load power to the end with the higher load power, active support and reactive compensation are provided, and closed-loop operation and current control between different buses of the same transformer substation are achieved. In emergency, when one bus is in fault and power failure, the interconnection switch is switched on, and the other bus which normally runs supplies power to the load in the fault bus, so that the load pressure of the same transformer substation is shared.

Referring to fig. 5, a first input end is electrically connected to a first bus bar, a second input end is electrically connected to a second bus bar, the first bus bar and the second bus bar are located in different substations, and the first input end and the second input end are any two input ends among all the input ends.

The third bus is electrically connected with the input of the first AC/DC bidirectional converter VSC1 and the fourth bus is electrically connected with the input of the second AC/DC bidirectional converter VSC 2. If the load rate of the third bus is low and the load of the fourth bus is high at a certain moment, the first AC/DC bidirectional converter VSC1 and the second AC/DC bidirectional converter VSC2 control the power to flow from the end with the lower load power to the end with the higher load power, active support and reactive compensation are provided, and closed-loop operation and tide flow control of different substation buses are achieved. In emergency, when one bus is in fault and power failure, the interconnection switch is switched on, and the buses in normal operation of different transformer stations supply power to the load in the fault bus, so that the pressure of a transformer substation at the end of the fault bus is reduced.

Referring to fig. 6, the first input end is electrically connected to a fifth feeder line, the second input end is electrically connected to a sixth feeder line, the fifth feeder line and the sixth feeder line are feeder lines of different busbars of different transformer substations, and the first input end and the second input end are any two input ends of all the input ends.

The fifth feed line is electrically connected to the input of the first AC/DC bi-directional converter VSC1 and the sixth feed line is electrically connected to the input of the second AC/DC bi-directional converter VSC 2. If the load rate of the fifth feeder line is low at a certain moment, and the load of the sixth feeder line is high, the first AC/DC bidirectional converter VSC1 and the second AC/DC bidirectional converter VSC2 are used for controlling power to flow from the end with low load power to the end with high load power, active support and reactive compensation are provided, and closed-loop operation and tide flow control of different feeders of different buses of different substations are achieved. In emergency, when one section of feeder line is in fault and power is cut off, the interconnection switch is switched on, and the other normally-operating feeder line supplies power to a load in the fault feeder line, so that the pressure of a bus at the end of the fault feeder line is reduced.

Referring to fig. 7, a direct current bus is arranged between adjacent AC/DC bidirectional converters, two ends of the direct current bus are respectively electrically connected with AC ends of different AC/DC bidirectional converters, and the direct current bus is connected to a new energy power supply. The new energy power supply comprises photovoltaic, energy storage and other new energy power supplies, and the new energy power supply is connected to supply power for various direct current loads, so that the diversity of system energy supply is increased, and the system reliability is improved.

It should be noted that the flexible interconnection apparatus for the distribution network in the above embodiment is only described as two AC/DC bidirectional converters, but of course, the AC/DC bidirectional converters may include three or more. As shown in fig. 8, the power distribution network flexible interconnection apparatus in fig. 8 includes three AC/DC bidirectional converters and three mechanical interconnection switches CS, and interconnection between three lines can be realized by using the power distribution network flexible interconnection apparatus in fig. 8, which is not specifically described.

Through the flexible interconnection device of distribution network that this application provided, can effectively adjust the difference with power consumption load peak and low ebb between transformer substation and the different transformer substations, alleviate high load transformer substation and use the high-power operating pressure of peak period at power consumption, improve the energy utilization of underload transformer substation simultaneously.

Corresponding to the power distribution network flexible interconnection device provided by the embodiment, the application also provides an embodiment of a control method of the power distribution network flexible interconnection device.

Referring to fig. 9, the control method of the power distribution network flexible interconnection device includes:

and S101, judging the running state of the substation.

And S102, if the transformer substation normally runs, the mechanical interconnection switch CS is kept to be switched off, the AC/DC bidirectional converter realizes interconnection between a power distribution network bus or a feeder line, and power flow is controlled.

When the transformer substation normally operates, the interconnection switch of the device keeps an opening state, the flexible multi-state switch operates to realize interconnection between buses/feeders of the power distribution network, and power flow is controlled, so that the power distribution network operates in a closed loop mode.

S103, if the transformer substation runs abnormally, determining an abnormal bus or feeder line, and switching the line through the mechanical interconnection switch CS.

Under emergency, if a certain section of bus breaks down and is powered off, the device contact switch is switched on, the other normally-running buses replace the fault bus, and meanwhile, resources such as energy storage in the direct-current bus and the like can be used for supplying power to a load in the fault bus through inversion of the bidirectional converter, so that the running stability of the system is greatly improved.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims

1. A distribution network flexible interconnection device, characterized by, includes: the system comprises a plurality of AC/DC bidirectional converters, a plurality of control circuits and a plurality of control circuits, wherein DC ends of the AC/DC bidirectional converters are electrically connected, and AC ends of the AC/DC bidirectional converters are electrically connected with input ends; and mechanical interconnection switches are arranged in front of the two different groups of AC/DC bidirectional converters and are respectively connected with the AC ends of the AC/DC bidirectional converters in an electric connection mode.

2. The distribution network flexible interconnection device of claim 1, wherein a first input is electrically connected to a first feeder line, a second input is electrically connected to a second feeder line, the first feeder line and the second feeder line are feeder lines of a same bus of a same substation, and the first input and the second input are any two of all the input ends.

3. The distribution network flexible interconnection device of claim 1, wherein the first input is electrically connected to a third feeder, the second input is electrically connected to a fourth feeder, the third feeder and the fourth feeder are feeders of different buses of the same substation, and the first input and the second input are any two of all the inputs.

4. The distribution network flexible interconnection device of claim 1, wherein a first input terminal is electrically connected to a first bus bar, a second input terminal is electrically connected to a second bus bar, the first bus bar and the second bus bar are located in a same substation, and the first input terminal and the second input terminal are any two of all input terminals.

5. The distribution network flexible interconnection device of claim 1, wherein the first input terminal is electrically connected to a third bus bar, the second input terminal is electrically connected to a fourth bus bar, the third bus bar and the fourth bus bar are located at different substations, and the first input terminal and the second input terminal are any two of all input terminals.

6. The distribution network flexible interconnection device of claim 1, wherein the first input is electrically connected to a fifth feeder, the second input is electrically connected to a sixth feeder, the fifth feeder and the sixth feeder are feeders for different busbars of different substations, and the first input and the second input are any two inputs from among all the inputs.

7. The distribution network flexible interconnection device of any one of claims 1 to 6, wherein a direct current bus is arranged between adjacent AC/DC bidirectional converters, two ends of the direct current bus are respectively electrically connected with DC ends of different AC/DC bidirectional converters, and the direct current bus is connected to a new energy power supply.

8. The distribution network flexible interconnection device of claim 7, wherein the mechanical interconnection switch is normally open in an initial state.

9. A method for controlling a flexible interconnection device of a power distribution network, the method being used for controlling the flexible interconnection device of the power distribution network according to any one of claims 1 to 8, and the method comprising:

judging the running state of the transformer substation;

if the transformer substation normally operates, the mechanical interconnection switch is kept to be switched off, the AC/DC bidirectional converter realizes interconnection between a bus or a feeder of the power distribution network, and power flow is controlled;

alternatively, the first and second electrodes may be,

and if the transformer substation runs abnormally, determining an abnormal bus or feeder line, and switching the lines through the mechanical interconnection switch.

10. The method for controlling the flexible interconnection device of the power distribution network according to claim 9, wherein the line switching is performed through a mechanical interconnection switch, and comprises the following steps: and controlling a mechanical interconnection switch connected with the abnormal bus or the feeder line to be switched on, and replacing the abnormal bus or the feeder line with the bus or the feeder line electrically connected with the mechanical interconnection switch.