CN113629691A

CN113629691A - Direct-current micro-grid system with double voltage levels and double-grid architecture

Info

Publication number: CN113629691A
Application number: CN202010379709.2A
Authority: CN
Inventors: 周锡卫
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-05-06
Filing date: 2020-05-06
Publication date: 2021-11-09

Abstract

The invention belongs to the technical field of microgrids, and in particular relates to a direct current microgrid system with a dual-voltage level and dual-grid architecture. Taking into account the convenience of electrochemical energy storage applications and the characteristics of different voltage levels of different types of batteries, application in suitable power consumption scenarios is conducive to service life and safe operation; for electric vehicle fast charging piles, medium and high voltage DC is generally used. Most of the information equipment using DC power uses low-voltage DC power, and important electrical equipment requires dual-circuit power supply; the invention constructs a medium-high voltage DC microgrid based on a medium-high voltage DC bus and a low-voltage DC bus based on the low-voltage DC bus. The flexible architecture of DC microgrid and dynamic integration reduces power conversion and improves efficiency, especially for the integration of different types of energy storage systems and the healthy, safe, and long-life operation of DC microgrids with two voltage levels and dual-grid architecture That is, independent and integrated can realize dual power supply, which greatly improves the reliability of power supply.

Description

Direct-current micro-grid system with double voltage levels and double-grid architecture

Technical Field

The invention belongs to the technical field of micro-grids, and particularly relates to a direct-current micro-grid system with a double-voltage-level double-grid framework.

Background

One of the important functions of the microgrid is to bring the advantages of the new energy distributed power generation into play, minimize the influence and large impact of the new energy distributed power generation on the power fluctuation of the connected large power grid, and the microgrid is an effective way for regionally organizing and connecting the new energy distributed power generation. The micro-grid can flexibly optimize the power supply and demand structure, the power resource allocation, the power dispatching and the like, can optimize and improve the resource utilization efficiency of the system, improves the reliability and the safety of the power system, reduces the influence and the burden of new energy power on the large power grid, and improves the negative influence of power generation and power supply on the environment. The unique advantages of the micro-grid are strongly concerned and paid attention by countries in the world.

From the demand of electricity consumption of users, the demand of direct current is always existed and continuously expanded, and especially, the facilities for charging electric vehicles and using direct current power supplies in the data and information processing field are wider and more increased; the regional power expansion and transformation difficulty is high, and the defects of instability and intermittence exist when new energy distributed power such as wind, light and the like is adopted; aiming at the application requirement, a direct current micro-grid formed by combining wind, light and other new energy distributed power with an energy storage system is one of the better solutions at present. Therefore, the invention provides a direct current micro-grid system with a double-voltage-level double-grid framework, which adopts a flexible framework dynamically fused with a medium-high voltage direct current micro-grid based on a medium-high voltage direct current bus and a low-voltage direct current micro-grid based on a low-voltage direct current bus, reduces power conversion, improves efficiency, is particularly beneficial to the healthy, safe and long-life operation of an energy storage system, realizes double-path power supply by the independent and fusion of the direct current micro-grids with the two-voltage-level double-grid framework, and greatly improves the reliability of power supply.

Disclosure of Invention

In order to realize safe, efficient, economic and reliable power supply and provide stable power support for loads with different voltage levels, the invention specifically discloses a direct-current micro-grid system with a double-voltage-level double-grid framework, which mainly comprises the following steps: the system comprises a direct current micro-grid EMS master control system, a medium-high voltage direct current bus, a low-voltage direct current power bus communication network, an electric control switch for connecting the medium-high voltage direct current bus with a charging pile, medium-high voltage direct current power supply DC/DC of a double-path power supply load, medium-high voltage support energy storage DC/DC, a medium-high voltage support energy storage battery pack string, a medium-voltage new energy power generation DC/DC, a medium-high voltage new energy power generation system, low-voltage support energy storage DC/DC, a low-voltage support battery pack string, DC/DC for connecting the medium-high voltage direct current bus with the low-voltage direct current bus, an important load of double-path power supply, a medium-high voltage direct current load, a medium-high voltage direct current charging pile, low-voltage new energy power generation DC/DC, a low-voltage new energy power generation system, a low-voltage direct current communication device, a low-voltage direct current protection and measurement and control device and a low-voltage direct current load, wherein:

the medium-high voltage direct current bus is connected with important loads of double-path power supply through medium-high voltage direct current power supply DC/DC of double-path power supply loads, connected with a medium-voltage support energy storage battery pack string through medium-voltage support energy storage DC/DC, connected with a medium-voltage new energy power generation system through medium-voltage new energy power generation DC/DC, connected with a medium-high voltage direct current charging pile through an electric control switch connected with the medium-high voltage direct current bus and directly connected with a medium-high voltage direct current load (51) to form a medium-high voltage direct current micro-grid;

the low-voltage direct-current micro-grid is formed by connecting a low-voltage support battery pack string with a low-voltage direct-current power bus through a low-voltage support energy storage DC/DC respectively, connecting a low-voltage new energy power generation system with a low-voltage new energy power generation DC/DC, and connecting a low-voltage direct-current communication device, a low-voltage direct-current protection and measurement and control device and a low-voltage direct-current load with the low-voltage direct-current power bus respectively;

the medium-high voltage direct current bus is connected with the low-voltage direct current power bus through a DC/DC (direct current/direct current) which is used for connecting the medium-high voltage direct current bus with the low-voltage direct current bus, so that a direct current micro-grid system with double voltage levels, in which a medium-high voltage direct current micro-grid and a low-voltage direct current micro-grid are operated in a fusion manner, is formed;

the direct-current micro-grid EMS master control system is respectively connected with an electric control switch connected with a middle-high voltage direct-current bus and a charging pile through a communication network, a middle-high voltage direct-current power supply DC/DC of a two-way power supply load, a middle-voltage support energy storage DC/DC, a middle-voltage support energy storage battery pack string, a middle-voltage new energy power generation DC/DC, a middle-voltage new energy power generation system, a low-voltage support energy storage DC/DC, a low-voltage support battery pack string, a DC/DC connected with the middle-high voltage direct-current bus and the low-voltage direct-current bus, important loads of double-path power supply, medium-high voltage direct current loads, medium-high voltage direct current charging piles, low-voltage new energy power generation DC/DC, a low-voltage new energy power generation system, low-voltage direct current communication equipment, low-voltage direct current protection and measurement and control equipment and low-voltage direct current loads form a direct current micro-grid system management and control system of a double-voltage-level double-grid framework in which a medium-high voltage direct current micro-grid and a low-voltage direct current micro-grid are operated in a fusion mode.

A direct current micro-grid system with a double-voltage-level double-grid framework is characterized in that a medium-high voltage direct current micro-grid and a low-voltage direct current micro-grid are operated in a fusion mode: the method comprises the steps of controlling the medium-voltage support energy storage DC/DC to be a voltage source of a medium-voltage and high-voltage direct-current micro-grid and controlling the balance of power and load power in the medium-voltage micro-grid, controlling the low-voltage support energy storage DC/DC to be a voltage source of a low-voltage direct-current micro-grid and controlling the balance of power and load power in the low-voltage micro-grid, controlling the DC/DC connected with a medium-voltage direct-current bus and a low-voltage direct-current bus in real time to adjust the surplus of electric quantity of the medium-voltage and high-voltage direct-current micro-grid and the low-voltage direct-current micro-grid, and achieving the fusion operation of the medium-voltage and high-voltage direct-current micro-grid and the low-voltage direct-current micro-grid.

The direct-current microgrid system with the double-voltage-level double-network architecture fully considers the convenience of electrochemical energy storage application and different voltage-level characteristics of different types of batteries, and aims at that lead-carbon batteries and lithium ion batteries have KV direct-current voltage capacity, and batteries containing galvanic piles (vanadium redox flow batteries and hydrogen fuel batteries) are used in a low-voltage direct-current scene, so that the service life is prolonged and the safe operation is facilitated; then, the electric vehicle quick charging pile generally adopts medium-high voltage direct current power, most information equipment of direct current power utilization uses low-voltage direct current power, and important power utilization equipment needs double-path power supply; the direct-current micro-grid system with the double-voltage-level double-grid framework is adopted, a dynamic fusion flexible framework of a medium-high-voltage direct-current micro-grid based on a medium-high-voltage direct-current bus and a low-voltage direct-current micro-grid based on a low-voltage direct-current bus is constructed, power conversion is reduced, efficiency is improved, fusion of different types of energy storage systems and healthy, safe and long-life operation are facilitated, the direct-current micro-grids with the two-voltage-level double-grid framework are independent and fused, double-path power supply can be achieved, and reliability of power supply is greatly improved.

Drawings

Fig. 1 is a schematic block diagram of a dc micro-grid system with a dual-voltage-level dual-grid architecture and a structure thereof.

Detailed Description

A dc microgrid system having a dual-voltage-level dual-grid architecture is described as an embodiment example, but the described embodiment is a part of, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The techniques and schemes of the present invention are not limited to those given in this example.

As shown in fig. 1, a dc micro-grid system with a dual-voltage-level dual-grid architecture mainly includes: the system comprises a direct-current micro-grid EMS master control system (10), a medium-high voltage direct-current bus (11), a low-voltage direct-current power bus (12) communication network (13), an electric control switch (14) for connecting the medium-high voltage direct-current bus with a charging pile, a medium-high voltage direct-current power supply DC/DC (20) of a double-path power supply load, a medium-voltage support energy storage DC/DC (21), a medium-voltage support energy storage battery pack string (201), a medium-voltage new energy power generation DC/DC (22), a medium-voltage new energy power generation system (202), a low-voltage support energy storage DC/DC (31), a low-voltage support battery pack string (301), a DC/DC (40) for connecting the medium-high voltage direct-current bus with the low-voltage direct-current bus, an important load (50) of the double-path power supply, a medium-high voltage direct-current load (51), a medium-high voltage direct-current charging pile (52), a low-voltage new energy power generation DC (60), a low-voltage new energy power generation system (601), Low-voltage direct current communication equipment (70), low-voltage direct current protection and measurement and control equipment (71), low-voltage direct current load (72), wherein:

the medium-high voltage direct current micro-grid is formed by connecting an important load (50) of double-path power supply through a medium-high voltage direct current power supply DC/DC (20) of a double-path power supply load by a medium-high voltage direct current bus (11), connecting a medium-voltage support energy storage battery pack string (201) through a medium-voltage support energy storage DC/DC (21), connecting a medium-voltage new energy power generation system (202) through a medium-voltage new energy power generation DC/DC (22), connecting a medium-high voltage direct current charging pile (52) and directly connecting a medium-high voltage direct current load (51) through an electric control switch (14) connected with the charging pile through the medium-high voltage direct current bus, and stabilizing the power fluctuation of the medium-voltage new energy power generation system (202) connected with the medium-voltage new energy power generation DC/DC (22) by the medium-voltage support energy storage DC/DC (21) and maintaining the voltage stability of the medium-high voltage direct current bus (11);

the low-voltage direct-current micro-grid is formed by connecting a low-voltage support battery pack string (301) with a low-voltage direct-current power bus (12) through a low-voltage support energy storage DC/DC (31), connecting a low-voltage new energy power generation system (601) through a low-voltage new energy power generation DC/DC (60), and connecting a low-voltage direct-current communication device (70), a low-voltage direct-current protection and measurement and control device (71) and a low-voltage direct-current load (72) respectively, wherein the low-voltage support energy storage DC/DC (31) is used for stabilizing the power fluctuation of the low-voltage new energy power generation system (601) and maintaining the voltage stability of the low-voltage direct-current power bus (12);

the medium-high voltage direct current bus (11) is connected with the low-voltage direct current power bus (12) through a DC/DC (40) which is connected with the medium-high voltage direct current bus and the low-voltage direct current bus to form a direct current micro-grid system which is operated by fusing a medium-high voltage direct current micro-grid and a low-voltage direct current micro-grid and has a double-voltage-level double-grid framework, so that energy interaction between the direct current micro-grid systems of the double-voltage-level double-grid framework is realized, full-member sharing of electric energy resources is achieved, and the resource utilization rate of the micro-grid is improved;

the direct-current micro-grid EMS master control system (10) is respectively connected with an electric control switch (14) for connecting a middle-high voltage direct-current bus with a charging pile through a communication network (13), a middle-high voltage direct-current power supply DC/DC (20) of a two-way power supply load, a middle-high voltage support energy storage DC/DC (21), a middle-voltage support energy storage battery pack string (201), a middle-voltage new energy power generation DC/DC (22), a middle-voltage new energy power generation system (202), a low-voltage support energy storage DC/DC (31), a low-voltage support battery pack string (301), a DC/DC (40) for connecting the middle-high voltage direct-current bus with the low-voltage direct-current bus, an important load (50) of two-way power supply, a middle-high voltage direct-current load (51), a middle-high voltage direct-current power supply (52), a low-voltage new energy power generation DC (60), a low-voltage new energy power generation system (601), a low-voltage direct-current communication device (70), The low-voltage direct current protection and measurement and control equipment (71) and the low-voltage direct current load (72) form a direct current micro-grid system management and control system of a double-voltage-level double-grid framework, wherein the medium-high voltage direct current micro-grid and the low-voltage direct current micro-grid are in fusion operation.

A direct current micro-grid system with a double-voltage-level double-grid framework is characterized in that a medium-high voltage direct current micro-grid and a low-voltage direct current micro-grid are operated in a fusion mode: the method comprises the steps of controlling a medium-voltage support energy storage DC/DC (21) to be a voltage source of a medium-voltage and high-voltage direct-current micro-grid and controlling the balance of power and load power in the medium-voltage micro-grid, controlling a low-voltage support energy storage DC/DC (31) to be a voltage source of a low-voltage direct-current micro-grid and controlling the balance of power and load power in the low-voltage micro-grid, and controlling a DC/DC (40) connected with a medium-voltage and high-voltage direct-current bus and a low-voltage direct-current bus in real time to adjust the surplus of electric quantity of the medium-voltage and high-voltage direct-current micro-grid and the low-voltage direct-current micro-grid so as to realize the fusion operation of the medium-voltage and high-voltage direct-current micro-grid and the low-voltage direct-current micro-grid.

The direct-current microgrid system with the double-voltage-level double-network architecture fully considers the convenience of electrochemical energy storage application and different voltage-level characteristics of different types of batteries, and aims at that lead-carbon batteries and lithium ion batteries have KV direct-current voltage capacity, and batteries containing galvanic piles (vanadium redox flow batteries and hydrogen fuel batteries) are used in a low-voltage direct-current scene, so that the service life is prolonged and the safe operation is facilitated; medium-high voltage and direct current power is generally adopted for the quick charging pile of the electric automobile, most information equipment of direct current power utilization uses low-voltage direct current power, and important power utilization equipment needs double-path power supply; the invention constructs the flexible framework of dynamic fusion of the medium-high voltage direct current micro-grid based on the medium-high voltage direct current bus and the low-voltage direct current micro-grid based on the low-voltage direct current bus, reduces power conversion, improves efficiency, is particularly beneficial to fusion of different types of energy storage systems and healthy, safe and long-life operation, realizes double-path power supply by independently and fusing the direct current micro-grids of two voltage level double-grid frameworks, and greatly improves the reliability of power supply.

Claims

1. A flow microgrid system with a dual voltage level and dual network architecture, mainly comprising: a DC microgrid EMS master control system (10), a medium voltage DC bus (11), a low voltage DC power bus (12) a communication network (13) , the electric control switch (14) connecting the medium voltage DC bus and the charging pile, the medium voltage DC power supply DC/DC (20) for the dual power supply load, the medium voltage support energy storage DC/DC (21), the medium voltage support energy storage Battery string (201), medium voltage new energy power generation DC/DC (22), medium voltage new energy power generation system (202), low voltage support energy storage DC/DC (31), low voltage support battery string (301), connection DC/DC of medium voltage DC bus and low voltage DC bus (40), important load of dual power supply (50), medium voltage DC load (51), medium voltage DC charging pile (52), low voltage new energy power generation DC/DC (60), low-voltage new energy power generation system (601), low-voltage DC communication equipment (70), low-voltage DC protection and measurement and control equipment (71), low-voltage DC load (72), wherein:

The medium voltage DC bus (11) is respectively connected to the important load (50) of the dual power supply through the medium voltage DC power supply DC/DC (20) of the dual power supply load, and is connected to the middle voltage support energy storage DC/DC (21) through the medium voltage DC/DC (21). An electric control switch (14) connected to a medium-voltage new energy power generation system (202) through a medium-voltage new energy power generation DC/DC (22), and connected to a charging pile through a medium-voltage DC busbar The medium-voltage DC charging pile (52) is connected and the medium-voltage DC load (51) is directly connected to form a medium-voltage DC microgrid;

The low-voltage DC power busbar (12) is respectively connected to the low-voltage support battery string (301) through the low-voltage support energy storage DC/DC (31), and is connected to the low-voltage new energy power generation system (601) through the low-voltage new energy power generation DC/DC (60). and are respectively connected with low-voltage DC communication equipment (70), low-voltage DC protection and measurement and control equipment (71), and low-voltage DC loads (72) to form a low-voltage DC microgrid;

The medium-voltage DC busbar (11) is connected to the low-voltage DC power busbar (12) through the DC/DC (40) connecting the medium-voltage DC busbar and the low-voltage DC busbar to form a dual-mode integrated operation of the medium-voltage DC microgrid and the low-voltage DC microgrid. DC microgrid system of voltage level;

The direct current microgrid EMS master control system (10) is respectively connected to the electric control switch (14) connected with the medium voltage direct current busbar and the charging pile, the medium voltage direct current power supply DC/DC (20) of the dual power supply load, the medium voltage direct current power supply DC/DC (20), Medium voltage support energy storage DC/DC (21), medium voltage support energy storage battery string (201), medium voltage new energy power generation DC/DC (22), medium voltage new energy power generation system (202), low voltage support energy storage DC/DC (31), low-voltage supporting battery string (301), DC/DC (40) connecting medium-voltage DC bus and low-voltage DC bus, important load with dual power supply (50), medium-voltage DC load (51) , medium voltage DC charging pile (52), low voltage new energy power generation DC/DC (60), low voltage new energy power generation system (601), low voltage DC communication equipment (70), low voltage DC protection and measurement and control equipment (71), low voltage DC The load (72) constitutes a DC micro-grid system management and control system with a dual-voltage level and dual-grid architecture in which the medium-voltage DC micro-grid and the low-voltage DC micro-grid operate in an integrated manner.

2. According to claim 1, a DC micro-grid system with dual-voltage level and dual-grid architecture, wherein the integrated operation of the medium-voltage DC micro-grid and the low-voltage DC micro-grid is characterized by: controlling the medium-voltage support energy storage DC/DC (21) It is the voltage source of the medium-voltage DC microgrid and controls the balance of power supply and load power in the medium-voltage microgrid, and controls the low-voltage support energy storage DC/DC (31) as the voltage source of the low-voltage DC microgrid and controls the low-voltage microgrid. Balance of power supply power and load power, real-time control of the DC/DC (40) connecting the medium-voltage DC busbar and the low-voltage DC busbar to adjust the surplus and deficiency of the medium-voltage DC microgrid and the low-voltage DC microgrid, and realize the medium-voltage DC microgrid and low-voltage DC. Microgrid integration operation.