WO2019157707A1

WO2019157707A1 - Multi-port electric energy exchanger

Info

Publication number: WO2019157707A1
Application number: PCT/CN2018/076833
Authority: WO
Inventors: 段青; 盛万兴; 孟晓丽; 沙广林; 吕广宪; 李振; 赵彩虹; 马春艳
Original assignee: 中国电力科学研究院有限公司
Priority date: 2018-02-14
Filing date: 2018-02-14
Publication date: 2019-08-22

Abstract

A multi-port electric energy exchanger, comprising: a management and application module, used for implementing the control, energy management and scheduling, and autonomous running of a multi-port electric energy exchanger, coordination control, as well as coordination and optimization control with an upper energy management system; a control module, used for the access, conversion, operation, storage, and control of an information flow and a control flow; a communication module, used for providing internal and external real-time secure communication connections and information and control flow transmission to the multi-port electric energy exchanger; an electrical measurement sensing and protecting module, used for measuring, monitoring, and feeding back the operating state, electric energy quality and environment of the multi-port electric energy exchanger; an electric energy power conversion module, used for performing power conversion on an alternating current/direct current electric energy port; and the alternating current/direct current electric energy port, used for connecting an alternating/direct current feeder at a low voltage side of a substation or distribution transformer so as to receive electric energy, or used for supplying power to a distributed power supply, energy storage access, and different types of loads.

Description

Multi-port power exchanger

Technical field

The present invention relates to power technology, and more particularly to a self-healing multi-port power exchanger.

Background technique

The lack of primary equipment regulation and control capability in the power distribution system has become the main bottleneck that restricts the further improvement of the operation level of the power distribution system. Although the closed-loop power supply method can improve the operation economy and reliability of the power distribution system to a certain extent, it may bring about the cycle power, the electromagnetic ring network, and the negative problems such as expanding the fault range and increasing the short-circuit current. Moreover, the current usage mode is basically closed-loop design open-loop operation, which greatly limits the application scenario of the closed-loop power supply mode, and cannot meet the requirements of distributed power supply high-permeability access and the demand of AC-DC hybrid power distribution.

Summary of the invention

In order to solve at least the above technical problem, an embodiment of the present invention provides a self-healing multi-port power exchanger, which is capable of establishing a flexible interconnection system of feeders on a low-voltage side of a plurality of substations or distribution transformers based on a multi-port power exchanger. The problem of the application scenario that overcomes the closed-loop power supply is limited, the AC/DC hybrid power distribution problem, and the problem that the distributed power supply cannot be flexibly accessed.

The technical solution of the embodiment of the present invention is implemented as follows:

The embodiment of the invention provides a multi-port power exchanger, comprising:

a management and application module, configured to implement control, energy management scheduling, and autonomous operation of the multi-port power exchanger, coordinated control between the multi-port power exchangers, and coordination and optimization control with an upper energy management system;

a control module for accessing, transforming, computing, storing, and controlling the information flow and the control flow;

a communication module, configured to provide real-time secure communication connection and information flow, control flow transmission to the internal and external of the multi-port power exchanger, and provide a communication protocol conversion and a communication interface for multiple information access;

An electrical measurement sensing and protection module for measuring, monitoring, and feeding back the working state, power quality, and environment of the multi-port power exchanger, and collecting data for the multi-port power exchanger, the control system, and the smart device Intelligent sorting, calculation of intermediate data, stipulation of data format, and electrical protection;

The power conversion module includes a power electronic converter, an energy storage module, a high frequency transformer, a filter, and a drive protection controller for performing power conversion for the AC/DC power port;

The AC/DC power port has different voltage levels or different outlet modes for connecting the AC/DC feeder of the low voltage side of the substation or the distribution transformer to receive power, or for distributing power to the distributed power source. Access and power supply for different types of loads.

In the above solution, the number of the AC power ports is at least two, corresponding to the low-voltage side AC feeders connected to different substations or distribution transformers, for receiving power output of different substations or distribution transformers, or for supplying power to the AC load. ;

The power electronic converter includes an AC/DC converter, the number of the AC/DC converters is consistent with the number of the AC power ports, and the AC side of the AC/DC converter and the AC power port are one by one. Corresponding connection, the DC side of each of the AC/DC converters is connected to the DC power port, and is used for converting AC power outputted by the substation into DC power, and outputting to the DC power port;

The DC power port is at least one, and is connected to a DC side of the AC/DC converter of the AC power port for receiving input and output of DC power.

In the above solution, the energy storage module is connected to the DC power port through a first DC/DC converter included in the power electronic converter, and is used for performing power energy balance and power conversion of the DC power port. And voltage support, assisting in the completion of transient power fluctuations, scheduling, equipment fault crossing and power flow, and providing uninterruptible power supply functions, and can achieve peak clipping and / or valley filling.

In the above solution, the first DC/DC converter includes a high frequency transformer.

In the above solution, the first DC side of the second DC/DC converter in the power electronic converter is connected to the DC side of the AC/DC converter, and the second DC of the second DC/DC converter is The DC power port is connected to the side for bucking or boosting the DC power received from the connected AC/DC converter, and then outputting to the connected DC power port.

In the above solution, the output voltage of the DC side of the AC/DC converter connected to the second DC/DC converter exceeds the high voltage threshold or is lower than the low voltage threshold.

In the above solution, the voltage level of the DC power port corresponds to the number of the corresponding DC/DC converters connected to the DC/DC converter and the DC side output voltage of the AC/DC converter.

In the above solution, the energy storage module is further configured to stabilize a voltage of the DC power port in a fault state of the AC feeder, perform power energy balance, power conversion, voltage support of the DC power port, and assist in completing the distribution. Power supply fluctuations, scheduling, equipment fault traversal and power flow transfer, and provide uninterruptible power supply functions, and can achieve peak clipping and / or valley filling.

In the above solution, the DC/DC converter (including the aforementioned first DC/DC converter and the second DC/DC converter) is a bidirectional isolated or non-isolated DC/DC converter, and the bidirectional isolated DC/ The topology of the DC converter includes: inductor-capacitor (LC) series resonance, LC parallel resonance, inductor-inductor-capacitor (LLC) series-parallel resonance, capacitance-inductance-capacitance (CLLC) series resonance, and phase shift control.

In the above solution, the AC power port is further configured to be in a disconnected state when the connected AC feeder is in a fault state.

In the above solution, the AC power port is further configured to: when the connected AC feeder is not in a fault state, and the AC feeder connected to the part of the AC power port is in a fault state, according to the re-coordinated power allocation of the connected feeder. The power flow in the fault state is transferred.

In the above solution, the DC power port is also used for accessing a distributed power source, and/or for directly accessing a DC load.

In the above solution, the AC/DC converter connected to the AC power port adopts a multi-level topology or a single-level structure, and corresponds to a voltage level and a power level of the connected AC feeder;

Among them, the multi-level topology adopted includes: a modular multi-level structure, a cascaded H-bridge multi-level structure, a clamp-type cascade structure, and a three-phase linear cascade structure.

In the above solution, the AC feeders connected to the AC power port have the same voltage level, partially different or all different.

In the above solution, the AC/DC power port further includes an expandable power port configured to be a DC power port or an AC power port, and the attributes and quantities of the corresponding AC/DC converter or DC/DC converter, and The attributes of the extended power interface correspond to the number.

The embodiment of the present invention provides a self-healing multi-port power exchanger, which can replace the direct rigid electrical connection implemented by the tie switch in the related art, and the connection with the feeder based on the power port to realize the flexible interconnection of the multi-feeder. An AC/DC hybrid power distribution system architecture based on multi-port power exchangers for flexible distribution of high-permeability access to multiple regions or different voltage levels of substations and distribution transformers with low-voltage side feeders is established.

DRAWINGS

1A is a schematic structural diagram of a conventional sub-station single-contact power distribution system provided by the related art;

1B is a schematic structural diagram of a conventional inter-substation dual-contact power distribution system provided by the related art;

2A is a schematic structural diagram of a system of a self-healing multi-port power exchanger according to an embodiment of the present invention;

2B is a schematic structural diagram of a power distribution system for establishing a feeder flexible interconnection based on a self-healing multi-port power exchanger according to an embodiment of the present invention (the internal structure only gives the core part of the power conversion module);

3A is a schematic structural diagram of a power distribution system for establishing a flexible interconnection of feeders of the same voltage level based on a self-healing multi-port power exchanger according to an embodiment of the present invention (the internal structure only gives the core part of the power conversion module);

3B is a schematic structural diagram of a power distribution system for establishing a multi-voltage level feeder flexible interconnection based on a self-healing multi-port power exchanger according to an embodiment of the present invention (the internal structure only gives the core part of the power conversion module);

3C is a schematic structural diagram of a power distribution system for establishing a low-voltage AC flexible interconnection based on a self-healing multi-port power exchanger according to an embodiment of the present invention (the internal structure only gives the core part of the power conversion module);

4A is a schematic diagram of an LC series resonant structure of a bidirectional isolated DC/DC converter in a self-healing multi-port power exchanger according to an embodiment of the present invention;

4B is a schematic diagram of an LC parallel resonant structure of a bidirectional isolated DC/DC converter in a self-healing multi-port power converter according to an embodiment of the present invention;

4C is a schematic diagram of an LLC resonant structure of a bidirectional isolated DC/DC converter in a self-healing multi-port power exchanger according to an embodiment of the present invention;

4D is a schematic diagram of an LLC resonant structure of a bidirectional isolated DC/DC converter in a self-healing multi-port power exchanger according to an embodiment of the present invention;

4E is a schematic structural diagram of phase shift control of a bidirectional isolated DC/DC converter in a self-healing multi-port power exchanger according to an embodiment of the present invention;

5A is a clamp-type multi-level topology structure of an AC power port in a self-healing multi-port power exchanger according to an embodiment of the present invention;

5B is an H-bridge cascaded multi-level topology structure of an AC power port in a self-healing multi-port power exchanger according to an embodiment of the present invention;

FIG. 5C is a modular multi-level topology of an AC power port in a self-healing multi-port power exchanger according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is to be understood that the examples are provided to illustrate the invention and not to limit the invention. In addition, the embodiments provided below are part of the embodiments for implementing the present invention, and do not provide all the embodiments for implementing the present invention. In the case of no conflict, the technical solutions described in the embodiments of the present invention may be combined in any combination. Implementation.

It should be noted that, in the embodiments of the present invention, the terms "including", "including", or any other variations thereof are intended to cover a non-exclusive inclusion, such that a method or apparatus comprising a plurality of elements includes not only the Elements, but also other elements not explicitly listed, or elements that are inherent to the implementation of the method or device. In the absence of further limitation, an element defined by the phrase "comprising a ..." does not exclude the presence of additional related elements in the method or device including the element (eg, a step in the method or a unit in the device) The unit here may be part of a circuit, part of a processor, part of a program or software, etc.).

The architecture provided by the related art for the power distribution system includes a radial mode and a weak contact of the feeder. Referring to FIG. 1A and FIG. 1B, FIG. 1A is a schematic structural diagram of a conventional sub-station single-contact power distribution system provided by the related art, and the A substation bus 18 And B substation bus 19 is provided with distribution lines, including: circuit breaker 11, segment switch (in the normally closed state) 12, segment switch (in the normally closed state) 13, contact switch (in the normally open state) 14, minutes The segment switch (in the normally closed state) 15, the segment switch (in the normally closed state) 16 and the circuit breaker 17.

FIG. 1B is a schematic structural diagram of a conventional inter-substation dual-contact power distribution system provided by the related art. When the switch between the bus bar 209 and the bus bar 210 is in an off state, the following power distribution lines are involved:

One line includes: A substation bus 201, circuit breaker 202, sectional switch (in normally closed state) 203, sectional switch (in normally closed state) 204, circuit breaker 205, sectional switch (in normally closed state) 206, Section switch (in normally closed state) 207 and circuit breaker 208;

The other line includes: A substation bus 221, circuit breaker 211, sectional switch (in normally closed state) 212, sectional switch (in normally closed state) 213, circuit breaker 214, sectional switch (in normally closed state) 215 Section switch (in normally closed state) 216 and circuit breaker 208.

When the switch between bus 209 and bus 210 is closed, the following distribution lines are involved:

One line includes: A substation bus 201, circuit breaker 202, sectional switch (in normally closed state) 203, sectional switch (in normally closed state) 204, bus 209, circuit breaker 214, sectional switch (in normally closed state) 215, segment switch (in the normally closed state) 216 and circuit breaker 208;

The other line includes: A substation bus 221, circuit breaker 211, sectional switch (in normally closed state) 212, sectional switch (in normally closed state) 213, bus 210, circuit breaker 205, sectional switch (in normally closed) State) 206, segment switch (in normally closed state) 207 and circuit breaker 208.

The closed-loop power supply network formed by the segment switch and the tie switch shown in FIG. 1A is limited by the response speed, the action life, and the inrush current, and in order to further improve the reliability, it is necessary to construct multiple pieces as shown in FIG. 1B. When the line is used to ensure the fault of the line, the backup line is cut in time; the feeders connecting the two substations of the A substation and the B substation shown in Fig. 1A are called double contact feeders.

In actual situations, as the number of connected substations increases, the number of feeders connecting substations of different voltage levels is further increased, greatly increasing the complexity of the distribution system and the construction investment cost.

The open-loop power supply network shown in Figure 1B cannot meet the requirements of high-precision real-time operation optimization of power distribution system level when the renewable energy and load are frequently fluctuated, as well as the demand for active control of power flow and power quality.

In response to the above problems, embodiments of the present invention provide a self-healing multi-port power exchanger, which is capable of implementing a multi-feeder flexible interconnection architecture power distribution system (hereinafter also referred to as a power distribution system) based on a multi-port power exchanger. It can be applied to the low-voltage side of multiple (region), substation or distribution transformers to effectively solve the above problems.

2A is a schematic structural diagram of a system of a multi-port power exchanger according to an embodiment of the present invention, including: a management and application module, a control module, a communication module, an electrical measurement sensing and protection module, an electric energy conversion module, and an AC/DC power supply. port.

In FIG. 2A, a dashed box indicates an optional module of a multi-port power exchanger, a one-way dotted arrow indicates control flow, a two-way solid arrow indicates power flow, a two-way thick arrow indicates two-way information flow, and a one-way thick arrow indicates one-way information. Flow, the following describes each module.

The management and application module is a combination of firmware and software for multi-port power exchanger operation management, human-machine interface and application software; it is the management core of multi-port power exchanger for implementing control including multi-port power exchanger , energy management scheduling and autonomous operation functions, coordinated control functions between multi-port power exchangers, and coordination and optimization control functions with upper energy management systems.

A control module, a hardware and firmware complex for accessing, transforming, computing, storing, and controlling processing of information and control flows, including controllers, operators, memories, drives, and inputs/outputs at the hardware level ( I/O) interface.

a communication module for providing real-time secure communication connections and information flows, control flow transmissions for multi-port power exchangers, communication of various communication protocols, and communication interfaces for multiple information access;

Electrical measurement sensing and protection module for measuring and monitoring and feedback of multi-port power exchangers' working status, power quality and environment, data collection and intelligent finishing of multi-port power exchangers, control systems, and other smart devices And carry out the calculation of intermediate data, the specification of the data format, and the function for realizing electrical protection, mainly including various types of sensors, measuring devices and protection circuits on the hardware level;

The power power conversion module is the core physical module of the multi-port power exchanger, and is the main physical device of power control, mainly including various types of power electronic converters, energy storage modules, high frequency transformers, filters, drive protection controllers, etc. The firmware and interface, the characteristics of the power conversion module directly determine the performance of the entire multiport power switch.

AC/DC power ports, at least two, providing a variety of power interfaces to choose from, different interfaces and models for different users, such as AC power ports and DC power ports, can achieve different voltage levels or different Outlet methods, such as AC single-phase and three-phase systems, DC single-stage and bipolar systems, etc., are responsible for connecting substations or distribution transformers with low-voltage side-crossing/DC feeders, or for distributed power supplies, energy storage access, and different types. Load power supply.

As an example, the AC/DC power port of the multi-port power switch provided by the embodiment of the present invention includes: an AC power port (also referred to herein as an AC bus), and a DC power port (also referred to herein as a DC bus).

By way of example, a power electronic converter of a multi-port power exchanger provided by an embodiment of the invention includes an alternating current/direct current (AC/DC) converter (also referred to herein as a rectifier, such as a multi-level rectifier).

As an example, the bidirectional isolated DC/DC converter of the multi-port power exchanger provided by the embodiments of the present invention may further include a high frequency transformer.

In addition, the power conversion module of the multi-port power exchanger provided by the embodiment of the present invention may further include an energy storage module. Of course, the energy storage module may be configured in the line according to actual needs, so the energy storage module may be in the multi-port power exchanger. The default setting.

The number of AC power ports is at least two, corresponding to the AC feeders connected to the low voltage side of different substations or distribution transformers (also referred to as feeders in this paper), for example, AC feeders connected to different voltage levels, and AC feeders with different voltage levels. Or AC feeders of all different voltage levels for receiving electrical energy from different substations or distribution transformers, or for supplying AC loads.

The number of AC/DC converters is the same as the number of AC power ports. The AC side of the AC/DC converter is connected to the AC power port one by one. The DC side of each AC/DC converter is connected to the DC power port for the substation. The output AC power is converted into DC power and output to the DC power port.

The number of DC power ports is at least one, and is connected to the DC side of the AC/DC converter of the AC power port for receiving input and output of DC power; of course, the number of DC power ports may also be two or more. For example, two can be medium voltage DC power ports and low voltage DC power ports.

The energy storage module is connected to the DC power port through a first DC/DC converter in the power electronic converter for performing power energy balance, power conversion, voltage stabilization of the DC power port, assisting in completing distributed power fluctuation, Transient processes such as scheduling, equipment fault crossing and power flow, and providing uninterruptible power supply functions, and enabling peak clipping and/or valley filling; it should be noted that the first DC/DC converter is referred to herein as energy storage. A type of DC/DC converter connected by a module, rather than one or more DC/DC converters; when an energy storage module is pre-set in the distribution line, the energy storage module in the multi-port power exchanger can By default, the first DC/DC converter can also include a high frequency transformer.

In one embodiment, the second DC/DC converter in the power electronic converter may further include a high frequency transformer for the case where the output voltage of the DC side of the DC/AC converter exceeds a high voltage threshold or is lower than a low voltage threshold. The first DC side of the second DC/DC converter is connected to the DC side of the AC/DC converter, and the second DC side of the second DC/DC converter is connected to the DC power port for the connected AC/ After the DC power received by the DC converter is stepped down or boosted, it is output to the connected DC power port; it should be noted that the second DC/DC converter refers to a type of AC/DC converter connected to the DC power port. A DC/DC converter for distinguishing between a DC/DC converter connected to an energy storage module, rather than one or more DC/DC converters.

In one embodiment, when the DC power port is connected to the second DC/DC converter, the voltage level of the DC power port, the number of the corresponding second DC/DC converters, and the DC of the AC/DC converter The voltage of the side output corresponds.

In an embodiment, the energy storage module is further configured to: in a fault state of the AC feeder, the voltage of the stabilized DC power port is in a set voltage range, and is used to perform power energy balance, power conversion, and The voltage is stable, assisting in the transient process of distributed power fluctuation, scheduling, equipment fault crossing and power flow, and providing uninterruptible power supply function, and can achieve peak clipping and/or valley filling.

In an embodiment, the energy storage module is further configured to perform distributed power consumption and stabilize the output voltage of the DC power port when the DC power port is connected to the distributed power source, and cooperate with the control system and the energy management system. The port power switch enables flexible access and management of distributed power supplies.

In one embodiment, the DC/DC converter is a bidirectional isolated DC/DC converter, and the bidirectional isolated DC/DC converter employs a topology including any of the following: LC series resonance, LC parallel resonance, LLC series parallel resonance, and CLLC. Series resonance and phase shift control.

In one embodiment, for any of the AC power ports of the multi-port power exchanger, it is also used to be in a disconnected state when the connected AC feeder is in a fault state, and the technical effect of quickly blocking and resolving the fault area is achieved; When the AC feeder is not in a fault state, and the AC feeder connected to the other part of the AC power port is in a fault state, the AC power port of the non-faulty AC port can be re-coordinated according to the connected feeder. The power distribution is used to perform power flow transfer in the fault state.

In one embodiment, the DC power port of the multi-port power exchanger provides a DC power port outlet for accessing the DC distributed power source and the DC power load.

In one embodiment, for the AC power port of the multi-port power exchanger, the voltage level of the connected feeder and the power level correspond to the multi-level topology used by the AC/DC converter connected to the AC power port. For example, types of multi-level topologies include: modular multi-level structures, cascaded H-bridge multi-level structures, clamp-type cascade structures, and three-phase linear cascade structures.

In one embodiment, the alternating current feeders connected to the alternating current power port have the same voltage level, partially different or all different.

In one embodiment, the AC/DC power port further includes an expandable power port configured to be a DC power port or an AC power port, and an AC/DC converter or DC/DC converter corresponding to the extended power port The attributes and number of devices correspond to the attributes and quantities of the expandable power port.

In one embodiment, the AC/DC power port is integrated in the multi-port power exchanger, and the AC/DC power port is integrated to realize seamless and flexible conversion of AC/DC energy to achieve different voltage levels (for example, 110V). ～35KV) seamless connection between AC power ports and AC/DC power ports and multi-directional flow.

In one embodiment, for a plurality of AC power ports of the multi-port power exchanger, a DC output side of a plurality of correspondingly connected rectifiers (eg, multi-level rectifiers) is connected in parallel to a DC power port of the multi-port switch; Alternatively, the rectifier for the DC voltage output in the DC side of the rectifier to which the AC power port is connected is too high/low (eg, above the high voltage threshold or below the low voltage threshold), through DC/DC (DC/DC) The converter, such as a bidirectional isolated DC/DC converter, is connected to a DC power port, and the voltage level of the DC power port (for example, 200V to 60KV) is based on the output voltage of the plurality of rectifiers and the number of bidirectional isolated DC/DC converters used. It is determined that there is a flexible topological family structure suitable for each voltage level.

In one embodiment, for the energy storage module in the multi-port power exchanger, the bidirectional isolated DC/DC converter is connected to the DC power port of the multi-port power exchanger to implement distributed power consumption and stabilize the DC power port. Voltage and other functions to improve the power quality of the power distribution system; at the same time, the energy storage module can also control the protection needs according to the power distribution system and equipment failure, and assist the power flow to supply and fault crossing to maintain the stability function of the power distribution system.

An example of a power distribution system based on a self-healing multi-port power exchanger to establish a feeder flexible interconnect is described below.

Referring to FIG. 2B, FIG. 2B is a schematic structural diagram of a power distribution system based on a self-healing multi-port power exchanger 307 for establishing a feeder flexible interconnection according to an embodiment of the present invention. FIG. 2B shows an offshore wind power grid 301, a scaled wind power grid 302 and a scaled photovoltaic grid 303, a conventional power plant 304, a total of three power generation networks, and a distributed power supply DC access and DC load output for residents. DC grid 305.

The offshore wind power plant 301 delivers high-voltage AC power to the transmission grid through a step-up transformer (only the step-up transformer 311 is exemplarily shown in Fig. 2B), and then forms a distribution line of AC 35kV or less on the low-voltage side through the 110KV AC substation 3073. It is connected to the 110V to 35kV multi-port power exchanger 307 AC power port 3076.

The large-scale wind power generation network 302 delivers high-voltage alternating current electric energy to the transmission grid through a transformer (only the transformer 311 is exemplarily illustrated in Fig. 2B), and then through the 110KV alternating current substation 3071, the low-voltage side forms a distribution line of less than 35kV under the low voltage side, and 110V. The ~35kV multi-port power exchanger 307 is connected to the AC power port 3075 and is stepped down by the DC/DC converter 3077 and then transmitted to the DC power port 3074.

The large-scale photovoltaic power generation network 303 and the conventional power generation system 304 transmit high-voltage alternating current electric energy to the transmission power grid 3072 through a transformer (only the transformer 311 is exemplarily illustrated in FIG. 2B), and then pass through a 110KV alternating current substation to form an alternating current of 35 kV or less under the low voltage side. The electric line is connected to the 110V-35kV multi-port power exchanger 307 AC power port 3076. It is rectified into DC power by AC/DC converter 3076, and is stepped down by DC/DC converter 3077 and then transmitted to DC power port 3074.

In FIG. 2B, a flexible interconnection of three AC substations (AC grid) and one DC power station (DC grid) feeder is exemplified. It can be understood that in practice, a multi-port power exchange can be provided by the embodiment of the present invention. A flexible interconnection of feeders on the low-voltage side of two or more substations is implemented.

2B shows a multi-port power exchanger 307 that can implement AC-side power quality control through a multi-level rectifier connected to an AC power port, control the power flow direction through rectification/inversion, and pass through each AC power port and DC power. The port coordinately controls the AC/DC form energy conversion to realize multi-directional power flow stability control and instantaneous transfer, thereby forming a multi-feeder flexible interconnection architecture power distribution system based on the self-healing multi-port power exchanger 307.

The multi-port power exchanger 307 has a multi-voltage level AC power port 3071 to an AC power port 3073 (voltage level 110V to 35KV), and the multi-port power exchanger also includes a DC power port 3074 (voltage level 200V to 60KV). A plurality of AC/DC power ports correspond to feeders connected to the low-voltage side of the multi-region substation, thereby forming a flexible interconnected power distribution system for the feeders on the low-voltage side of the multi-region substation.

According to the dispatching needs of the power distribution system, active power control between the AC/DC feeders and the substation, power quality management of each AC power port of the multi-port power exchanger 307, fast isolation and self-healing protection in the fault area. Taking a multi-port power exchanger including AC power ports of different voltage levels as an example, the DC side of the multi-level rectifier of the AC power port of different voltage levels is connected in parallel to the DC power port of the multi-port power exchanger 307, thereby The AC power port forms an energy flow path by connecting to a DC power port.

The energy storage module can be connected to the DC power port 3074 of the multi-port power exchanger 307 through a bidirectional isolated DC/DC converter in the multi-port power exchanger 307. The bidirectional isolated DC/DC converter is used to provide energy balance and stabilize DC power. The voltage of port 3074 and the transient process and uninterruptible power supply support can assist in the completion of fault crossing and power flow transient process, and can achieve peak clipping and/or valley filling.

A power distribution system for a feeder interconnect architecture based on a self-healing multi-port power exchanger will continue to be described in conjunction with an example.

Referring to FIG. 3A, FIG. 3A is a schematic structural diagram of a power distribution system based on a self-healing multi-port power exchanger 407 for establishing a flexible interconnection of feeders of the same voltage level. The multi-port power exchanger 407 includes three 35KV or The 10KV AC power port is correspondingly recorded as an AC power port 4071, an AC power port 4072 and an AC power port 4073, and further includes a DC power port, which is recorded as a DC power port 4074.

The DC power port 4074 has a voltage rating of 60KV or 16KV, and the load accessed through the DC power port outlet 4075 includes a DC distributed power source 404 and a DC load 405.

Three 110KV incoming lines for the AC grid are shown in Figure 3A, including 110KV incoming lines 1, 110KV incoming lines 2, and 110KV incoming lines 3.

The 110KV incoming line 1 is connected to the AC power port of the multi-port power exchanger by the circuit breaker 4011, the main transformer 4021, the circuit breaker 4013, and the AC power transmitted to the AC power port 4071 is converted into DC power by the AC/DC converter 4076. And transmitted to the DC power port 4074;

The 110KV incoming line 2 is connected to the AC power port of the multi-port power exchanger by the circuit breaker 4012, the main transformer 4022, the circuit breaker 4014, and the AC power transmitted to the AC power port 4072 is converted into DC power by the AC/DC converter 4077. And transmitted to the DC power port 4074;

The 110KV incoming line 3 is connected to the AC power port 4073 of the multi-port power exchanger through the circuit breaker 4016, the main transformer 4023, and the circuit breaker 4015, and the AC power transmitted to the AC power port 4073 is converted into DC power by the AC/DC converter 4078. And transmitted to the DC power port 4074.

An energy storage device 4079 may also be provided in the multi-port power exchanger 407 for transmission to the DC power port 4074 via the DC/DC converter 4079 to DC power.

Referring to FIG. 3B, FIG. 3B is a schematic structural diagram of a power distribution system for establishing a multi-voltage level feeder flexible interconnection based on a self-healing multi-port power exchanger according to an embodiment of the present invention. The multi-port power exchanger includes a 35KV or 10KV AC power. Port 4073, two 10KV or 35KV AC power ports (ie, AC power port 4071 and AC power port 4072); also includes a 16KV or 60KV DC power port 4074.

The structure of FIG. 3B can be understood according to the foregoing description for FIG. 3A. It should be noted that the 110KV incoming line 3 is connected to the AC power port of the multi-port power exchanger via the circuit breaker 4013, the main transformer 4023, and the circuit breaker 4015, and is transmitted to the AC. The AC power of the power port 4073 is converted into DC power by the AC/DC converter 4078, and is also stepped down by the bidirectional isolated DC/DC converter 40710 and then transmitted to the DC power port 4074.

It can be seen from the above that the AC/DC power port shown in FIG. 3A and FIG. 3B corresponds to the feeder line drawn from the low voltage side of the transformer connected to different substations, and constitutes a power distribution system with different voltage levels and AC/DC feeder flexible interconnection.

It should be noted that the number of AC/DC power ports of the multi-port power exchangers in FIG. 3A and FIG. 3B is only an example. In practice, the number of AC/DC power ports is not limited to four, and feeders of different voltage levels may also be based on Actually, flexible interconnection is required through a multi-port power exchanger, for example, a flexible interconnection between an AC 110V feeder and a 380V feeder, a flexible interconnection between an AC 1KV feeder and an AC 3KV feeder, and an AC power port of the power exchanger can cover an AC voltage level of 110V. ~35kV, DC power port voltage can cover 200V ~ 60kV.

As an example, the voltage of the DC power port is determined according to the actual application, as shown in FIG. 3A. As an example, when the voltages of the three AC power ports (AC power port 4071 to AC power port 4073) are 10 KV, the voltage of the DC power port 4074 For 16KV, the DC side of the rectifier of each AC power port is directly connected in parallel to the DC power port 4; when the voltage of the three AC power ports is 35KV, the voltage of the DC power port is 60KV, and the DC side of the rectifier of each AC power port is directly Connect to DC power port 4 in parallel.

As an example, as shown in FIG. 3B, when the power exchanger includes a 35KV AC power port (ie, AC power port 4073) and two 10KV AC power ports (ie, AC power port 4071 and AC power port 4072), DC power port 4074 The voltage is 16KV, the DC side of the rectifier of the two 10KV AC power ports is directly connected in parallel to the DC power port, and the 35KV AC power port is too high in voltage level relative to other DC power ports and AC power ports (for example, Exceeding the high voltage threshold, or the magnitude of the difference is above the order of magnitude threshold), the DC side of its rectifier (ie, AC/DC converter 4078) can be stepped down by a bidirectional isolated DC/DC converter (ie, DC/DC converter 40710) Then, the DC side of the rectifier of the two 10KV AC power ports is connected in parallel to the DC power port 4074.

As an example, as shown in FIG. 3B, when the power exchanger includes a 10KV AC power port (ie, AC power port 4073) and two 35KV AC power ports (ie, AC power port 4071 and AC power port 4072), the DC power port is The DC side of the rectifier of the 60KV, 35KV AC power port (corresponding to AC/DC converter 4076 and AC/DC converter 4077) is directly connected in parallel to the DC power port 4074, and the 10KV AC power port is relatively DC power. The voltage level of port 4074 is too low (eg, below a predetermined low voltage threshold, or the magnitude of the difference is above an order of magnitude threshold), and the DC side of its rectifier (ie, AC/DC converter 4078) can be isolated by bidirectional isolation DC/DC After the converter (ie, DC/DC converter 40710) is boosted, it is connected in parallel with the DC side of the rectifier of the 60KV, 35KV AC power port to the DC power port 4074.

In one embodiment, the design of the voltage level of the DC power port uses the principle of minimizing the number of bidirectional isolated DC/DC converters used in the multiport power exchanger, the voltage level of the DC power port relative to the AC power port The voltage level is not too high or too low, for example, the two are at the same voltage level, or the difference in voltage level is within the voltage level difference; since the bidirectional isolated DC/DC converter can be set to overcome the excessive voltage level difference In the case where the bidirectional isolation DC/DC converter can be omitted in the case of a small difference in voltage levels, the multi-port power exchanger topology has a flexible topology family structure suitable for each voltage level.

Referring to FIG. 3C, FIG. 3C is a schematic structural diagram of a power distribution system for establishing a low-voltage AC flexible interconnection based on a self-healing multi-port power exchanger according to an embodiment of the present invention. The multi-port power exchanger includes: two low-voltage AC (400V) Port (ie AC power port 4076 and AC power port 4077), a medium voltage DC (800V) port (ie DC power port 4074), and a low voltage DC power port (ie DC power port 40712); AC power port 4071 and AC The DC side of the rectifier of the power port 4072 (corresponding to AC/DC converter 4076 and AC/DC converter 4077) is directly connected in parallel to the medium voltage DC power port (800V), and the medium voltage DC power port can be separately led to the DC power port. Facilitate access to distributed power, or directly connect to DC load

Since the voltage level of the low voltage DC power port is too low relative to other AC/DC power ports (eg, below a low voltage threshold, or the magnitude of the difference is above an order of magnitude threshold), the rectifier of the AC power port 4071 and the AC power port 4076 The DC side is stepped down by a bidirectional isolated DC/DC converter (ie, DC/DC converter 40711) and then paralleled to a low voltage DC power port.

The operation of the power distribution system of the feeder interconnect architecture based on the self-healing multi-port power exchanger will be described below.

As shown in FIG. 3A to FIG. 3C, a self-healing multi-port power exchanger is used to form a 110KV low-voltage side (35KV, 10KV) feeder flexible interconnection power distribution system, and an AC feeder (referred to as an AC incoming or incoming line) is realized. 2 and 3, with energy scheduling and power flow active control of the DC power port, the number of direct/AC power ports shown in FIG. 3A to FIG. 3C is only an example, and the number of AC/DC power ports in practical applications is not limited to four, and The voltage level of the interconnected feeders can also be connected according to actual needs, for example, a flexible interconnection between a 110V AC power port and a 380V AC power port, and an interconnection between a 1KV AC power port and a 3KV AC power port. Through the active power flow control capability of the self-healing multi-port power exchanger, the power flow distribution and energy management between the feeders in FIG. 3A to FIG. 3C are realized.

In the fault condition, for example, if the incoming line 1 fails, the fault area can be defined by quickly cutting off the AC power port 4071 to prevent the incoming line 1 fault from affecting the remaining feeders; after the AC power port 4071 is cut off, the power distribution of the remaining feeders can be re-coordinated. The power flow in the fault state is realized, and in the process, the energy storage module stabilizes the voltage of the DC power port, assists in completing transient processes such as power flow inversion and low voltage crossing of the switch, and improves the stability of the power distribution system.

In this way, the self-healing multi-port power exchanger is constructed by a flexible interconnected power distribution system, which realizes seamless connection of AC/DC feeders of different voltage levels, closed-loop intelligent control, and fault self-healing protection, and related technologies are based on Compared with the rigid connection of the contact switch, it has the advantages of control, coordination, energy efficiency and economy.

Next, the structure of the self-healing multi-port power exchanger will be exemplified.

As shown in FIG. 3A to FIG. 3C, in a power distribution system of a feeder flexible interconnect structure built by a self-healing multi-port power exchanger, the multi-port power exchanger is mainly composed of an AC/DC converter and a DC/DC converter. The components are connected by a DC power port, wherein the number of AC/DC converters can be determined according to the number of AC power ports connected to the feeder, that is, the number of AC/DC converters is the same as the number of AC power ports, Figure 3A In Fig. 3C, three different AC feeders are connected by the power exchanger, so there are three AC/DC converters.

In one embodiment, since the power exchanger is connected to an AC feeder of different voltage levels, the DC side output voltage of the rectifier for the AC power port is too high/low, and the AC/DC is at the corresponding AC power port. The DC side of the converter is provided with a DC/DC converter connected to the DC power port, and the output of the DC side of the AC/DC converter is stepped down/boosted and connected to the DC power port.

In one embodiment, as shown in FIG. 3B, the DC power port of the multi-port power exchanger can be directly connected to the distributed power source or directly connected to the DC load.

In one embodiment, the DC/DC converter of the multi-port power exchanger can employ a bidirectional isolated DC/DC converter, and the bidirectional isolated DC/DC converter inside the multi-port power exchanger can adopt various topologies such as a topology. 4A to 4E, including LC series resonance, LC parallel resonance, LLC series-parallel resonance, CLLC series resonance, and phase shift control.

In one embodiment, the AC power port of the multi-port power exchanger employs the multi-level topology shown in Figures 5A through 5C, including clamp type, H-bridge cascade type, modular multi-level, and three-phase linear stage. In addition, for the active bridges on both sides of the bidirectional isolated DC/DC converter shown in FIG. 4A to FIG. 4E, the multi-level structure shown in FIG. 5A to FIG. 5C can be selected according to the connected DC side voltage level. A bidirectional isolated DC/DC converter that forms a multilevel topology.

In one embodiment, for the control strategy employed by the bidirectional isolated DC/DC converter, as an example, the bidirectional isolated DC/DC converter illustrated in Figures 4A through 4D employs a variable frequency full resonance control strategy by varying the switching frequency. The transmission energy magnitude and direction are realized; the bidirectional isolated DC/DC converter shown in FIG. 4E adopts a fixed frequency phase shift control strategy, by changing the active bridge between the active bridges and the active bridge internal bridge arms in the bidirectional isolated DC/DC converter The phase shift angle between the two realizes the transmission energy magnitude and direction control; the CLLC series full resonance topology shown in Fig. 4D can adopt the fixed frequency phase shift control strategy by changing the active bridge between the active bridges in the bidirectional isolated DC/DC converter. The phase shift angle between the internal bridge arms of the bridge realizes the transmission energy magnitude and direction control. The CLLC series full resonance topology adopts the fixed frequency phase shift control strategy to realize the full load range soft switching while the intermediate transformer current approaches the sinusoidal waveform and the waveform coefficient. Well, the converter has lower on-state losses and lower switching losses.

In one embodiment, as shown in FIG. 3A to FIG. 3C, the 35KV (or 10KV) AC power port adopts a multi-level rectifier bridge structure in a power distribution system of a self-healing multi-port power exchanger feeder flexible interconnect power distribution system architecture. The multi-level structure is shown in Figure 5. The level and multi-level topology used are determined according to the multi-connection AC/DC voltage level and the application.

In summary, the embodiments of the present invention provide a direct rigid electrical connection using a self-healing multi-port power exchanger instead of a tie switch to realize flexible interconnection of multi-voltage level AC/DC feeders, and establish multiple based on the switch. Low-voltage side feeder flexible interconnect distribution system architecture for regional substations. The fault isolation capability of the DC link can quickly block and cut the fault area, block the short-circuit current path, suppress the rise of the short-circuit current, effectively reduce the scope of the fault; the fault protection and ride-through capability combined with the control and hardware, bypass fault unit Or device, realize dynamic topology reconstruction, effectively reduce fault loss; multi-directional power flow active control and power quality, improve power supply quality, and realize power customization requirements.

The above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the appended claims.

Industrial applicability

Embodiments of the present invention relate to a self-healing multi-port power exchanger, including: a management and application module, configured to implement control, energy management scheduling, and autonomous operation of the multi-port power switch, the multi-port power exchange Coordination control between the devices and coordination and optimization control with the upper energy management system; control module for accessing, transforming, transmitting and computing the information flow and the control flow; communication module for providing A real-time secure communication connection between the internal and external of the multi-port power exchanger, and provides a communication protocol conversion and a communication interface for multiple information access; an electrical measurement sensing and protection module for the multi-port power exchanger Measurement, monitoring and feedback of working status, power quality and environment, data collection and intelligent sorting of the multi-port power exchanger, control system and intelligent device, and calculation of intermediate data, and regularization of data format, And realize electrical protection; power power conversion module, including power electronic converter, high frequency transformer , a filter and a controller for power conversion for an AC/DC power port; the AC/DC power port having different voltage levels or different outgoing modes for connecting to a low voltage side of a substation or distribution transformer The AC/DC feeders receive power or are used to power distributed power supplies, energy storage access, and different types of loads. A low-voltage side feeder flexible interconnected power distribution system architecture for multiple regional substations or distribution transformers adapted to distributed power supply with high permeability access based on a power exchanger. Self-healing multi-port power exchanger for multi-directional power flow active control, AC/DC energy flexible and efficient conversion, fault self-healing protection and isolation, realize multi-region substation or distribution transformer low-voltage side multi-voltage grade AC and DC feeder flexibility Interconnection and energy coordination, online load balancing of multiple feeders, self-healing protection in fault state and instantaneous power supply to power flow, and convenient distribution of high-permeability access and AC/DC hybrid power distribution, improve the utilization rate of substation main equipment Improve power supply reliability and reduce power-off time of important loads.

Claims

A multi-port power exchanger comprising:

a management and application module, configured to implement control, energy management scheduling, and autonomous operation of the multi-port power exchanger, coordinated control between the multi-port power exchangers, and coordination and optimization control with an upper energy management system;

a control module for accessing, converting, computing, storing, and controlling processing of the information flow and the control flow;

a communication module, configured to provide real-time secure communication connection and information flow, control flow transmission to the internal and external of the multi-port power exchanger, and provide a communication protocol conversion and a communication interface for multiple information access;

An electrical measurement sensing and protection module for measuring, monitoring, and feeding back the working state, power quality, and environment of the multi-port power exchanger, and collecting data for the multi-port power exchanger, the control system, and the smart device, Intelligent sorting, calculation of intermediate data, stipulation of data format, and electrical protection;

The power conversion module includes a power electronic converter, an energy storage module, a high frequency transformer, a filter, and a drive protection controller for performing power conversion for the AC/DC power port;

The AC/DC power port has different voltage levels or different outlet modes for connecting the AC/DC feeder of the low voltage side of the substation or the distribution transformer to receive power, or for distributing power to the distributed power source. Access and power supply for different types of loads.
The multi-port power exchanger of claim 1 wherein

The AC power port has a quantity of at least two, corresponding to an AC feeder connected to a low voltage side of a different substation or a distribution transformer, for receiving power output by different substations or distribution transformers, or for supplying power to an AC load;

The power electronic converter includes an AC/DC converter, the number of the AC/DC converters is consistent with the number of the AC power ports, and the AC side of the AC/DC converter and the AC power port are one by one. Corresponding connection, the DC side of each of the AC/DC converters is connected to the DC power port, and is used for converting AC power outputted by the substation into DC power, and outputting to the DC power port;

The DC power port is at least one, and is connected to a DC side of the AC/DC converter of the AC power port for receiving input and output of DC power.
The multi-port power exchanger of claim 1 wherein

The energy storage module is connected to the DC power port through a first DC/DC converter in the power electronic converter for performing power energy balance, power conversion, and voltage stabilization of the DC power port. Auxiliary to complete transient processes such as distributed power fluctuations, scheduling, equipment fault traversal and power flow, and provide uninterruptible power supply functions, and can achieve peak clipping and / or valley filling.
A multi-port power exchanger as claimed in claim 3, wherein

The first DC/DC converter includes a high frequency transformer.
The multi-port power exchanger of claim 1 wherein

a first DC side of the second DC/DC converter in the power electronic converter is connected to a DC side of the AC/DC converter, and a second DC side of the second DC/DC converter is connected to the DC side The DC power port is used for bucking or boosting the DC power received from the connected AC/DC converter and outputting it to the connected DC power port.
A multi-port power exchanger as claimed in claim 5, wherein

The output voltage of the DC side of the AC/DC converter to which the second DC/DC converter is connected exceeds a high voltage threshold or is lower than a low voltage threshold.
A multi-port power exchanger as claimed in claim 5, wherein

The voltage level of the DC power port corresponds to the number of the corresponding DC/DC converters connected to the DC/DC converter and the DC side output voltage of the AC/DC converter.
The multi-port power exchanger of claim 1 wherein

The energy storage module is configured to stabilize a voltage of the DC power port in a fault state of the AC feeder, perform power energy balance, power conversion, voltage stability of the DC power port, and assist in completing distributed power fluctuation and scheduling. Transient processes such as equipment fault traversal and power flow transfer, as well as providing uninterruptible power supply functions and peak clipping and/or valley filling.
The multi-port power exchanger of claim 1 wherein

The DC/DC converter in the power electronic converter is a bidirectional isolated DC/DC converter, and the topology of the bidirectional isolated DC/DC converter includes one of the following: an inductor-capacitor LC series resonance, an LC parallel resonance, Inductance and Inductor Capacitance LLC series-parallel resonance, capacitance inductance inductance and capacitance CLLC series resonance and phase shift control.
The multi-port power exchanger of claim 1 wherein

The AC power port is further configured to be in a disconnected state when the connected AC feeder is in a fault state.
The multi-port power exchanger of claim 1 wherein

The AC power port is further configured to re-coordinate according to the connected feeder when the connected AC feeder is not in a fault state, and the AC feeder connected to a part of the AC power port of the multi-port power exchanger is in a fault state Power distribution, power flow transfer in the fault state.
The multi-port power exchanger of claim 1 wherein

The DC power port is also used for access to a distributed power source, and/or for direct access to a DC load.
The multi-port power exchanger of claim 1 wherein

The AC/DC converter connected to the AC power port adopts a multi-level topology or a single-level structure, and corresponds to a voltage level and a power level of the connected AC feeder;

Among them, the multi-level topology adopted includes one of the following: a modular multi-level structure, a cascaded H-bridge multi-level structure, a clamp-type cascade structure, and a three-phase linear cascade structure.
The multi-port power exchanger of claim 1 wherein

The AC feeders connected to the AC power port have the same voltage level, partially different or all different.
The multi-port power exchanger of claim 1 wherein

The AC/DC power port further includes an expandable power port configured to be a DC power port or an AC power port, and an attribute and quantity of an AC/DC converter or a DC/DC converter corresponding to the extended power port, Corresponding to the attributes and quantity of the expandable power port.