CN106786730A - A kind of new microgrid topological structure for extensive electric automobile - Google Patents

Abstract

The invention discloses a new micro-grid topology structure for large-scale electric vehicles, including: AC bus, first DC bus, second DC bus, power load system, energy storage system, distributed power supply and electric vehicles Charging station; distributed power supply, AC energy storage unit and AC load are respectively connected to the AC bus; the first DC bus and the second DC bus are respectively connected to the AC bus; the first DC bus is connected to residents’ DC loads, DC Energy storage unit, important loads and sensitive loads; the second DC bus is connected with industrial DC loads and electric vehicle charging stations. Utilizing the novel micro-grid topology provided by the present invention, AC and DC buses are used to separate the power load system in the micro-grid, which can reduce the impact of power quality degradation caused by the connection of large-scale electric vehicle charging stations, so as to ensure the important power consumption in the micro-grid. Continuous and reliable power supply for loads and sensitive loads.

Description

A Novel Microgrid Topology for Large-Scale Electric Vehicles

technical field

The invention relates to the technical field of power system network topology, in particular to a novel micro-grid topology for large-scale electric vehicles.

Background technique

As a new generation of transportation to replace traditional gasoline vehicles, electric vehicles have received strong support from all over the world, making electric vehicles widely popular in recent years. With the vigorous promotion of electric vehicles, in the construction planning of microgrids, when large-scale electric vehicles are connected to microgrids, since electric vehicles are used as constant power loads and directly connected to the AC bus of microgrids, they will be in the power supply system of microgrids. A large number of harmonics are introduced into the system, which further reduces the power supply quality of the power system. Therefore, it is necessary to establish a micro-grid structure in the application environment of large-scale electric vehicle access to reduce the impact of harmonics.

At present, as shown in Figure 1, the traditional microgrid structure includes: distributed power sources, energy storage systems and power load systems; among them, distributed power sources include wind power generators, solar generators or micro gas turbines for power generation; power load systems The system includes sensitive loads and important loads; the energy storage system includes DC energy storage units and AC energy storage units. All distributed power sources, energy storage systems and power load systems are connected to an AC bus, and fluctuations in distributed power sources and power load systems will affect the power quality of the microgrid.

However, when a large-scale electric vehicle is connected to the microgrid through the electric vehicle charging station, when the electric vehicle charging station starts or reaches the charging peak period, it may cause a power shortage in the microgrid, thereby affecting the frequency of the microgrid; and when the distributed The fluctuation of power output will directly affect the power supply quality of the power load system, and further affect the reliability of power quality in the microgrid.

Contents of the invention

The purpose of the present invention is to provide a new micro-grid topology for large-scale electric vehicles to solve the problem of reliability of power quality in the micro-grid when large-scale electric vehicles are connected to the micro-grid in the traditional micro-grid structure impact issues.

According to an embodiment of the present invention, a novel microgrid topology for large-scale electric vehicles is provided, including: an AC bus, a first DC bus, a second DC bus, a power load system, an energy storage system, a distribution type power supply and electric vehicle charging station, among which,

The energy storage system includes an AC energy storage unit and two DC energy storage units;

The power load system includes DC loads, AC loads, sensitive loads and important loads;

The DC loads include industrial DC loads and residential DC loads;

The AC bus is connected to the distribution network through a transformer and a main switch;

The distributed power supply, the AC energy storage unit and the AC load are respectively connected to the AC bus;

The first DC bus and the second DC bus are respectively connected to the AC bus;

The first DC bus includes a first segment of the first DC bus and a second segment of the first DC bus;

The first section of the first DC bus is connected to the residential DC load and a DC energy storage unit;

The first DC bus in the second section is connected with the important load, the sensitive load and another DC energy storage unit;

The second DC bus is connected to the industrial DC load and the electric vehicle charging station.

Preferably, the new microgrid topology for large-scale electric vehicles further includes: a tie line, the tie line is used to connect the distribution network and the second section of the first DC bus, the tie line The line is used to directly provide electric energy for the sensitive load and the important load through the connection line from the distribution network when there is a shortage of power in the microgrid; and/or, the connection line is used to connect the Electric vehicle charging station and the AC bus.

Preferably, the novel microgrid topology for large-scale electric vehicles further includes: a backup power supply connected to the second DC bus.

Preferably, the new microgrid topology for large-scale electric vehicles further includes: several rectifiers, several choppers, several inverters and several frequency converters;

The rectifier is arranged between the AC bus and the distributed power supply and between the second DC bus and the AC bus;

The choppers are respectively arranged between the residential DC load and the first DC bus bar of the first section, between the industrial DC load and the second DC bus bar, and between the DC energy storage unit and the first DC bus bar. Between the first DC bus, between the electric vehicle charging station and the second DC bus, and between the backup power supply and the second DC bus;

The inverter is arranged between the AC load and the AC bus, between the first DC bus and the AC bus, between the sensitive load and the first DC bus, and between the between the important load and the first DC bus;

The frequency converter is arranged between the distributed power supply and the AC bus and between the AC energy storage unit and the AC bus.

Preferably, the new microgrid topology for large-scale electric vehicles further includes several tie switches: each of the tie switches is respectively arranged between the rectifier and the AC bus, and the chopper and Between the first DC bus, between the chopper and the second DC bus, between the inverter and the AC bus, between the inverter and the AC bus, and Between the first section of the first DC bus and the second section of the first DC bus.

Preferably, the distributed power sources include: wind power generators, solar power generators and micro gas turbines.

Preferably, the AC loads include: industrial AC loads and residential AC loads.

Preferably, the backup power source is an internal combustion engine.

Preferably, the energy storage system is a storage battery.

It can be seen from the above technical solutions that the embodiment of the present invention provides a new micro-grid topology for large-scale electric vehicles, including: AC bus, first DC bus, second DC bus, power load system, energy storage system, a distributed power supply, and an electric vehicle charging station; the distributed power supply, the AC energy storage unit, and the AC load are respectively connected to the AC bus; the first DC bus and the second DC The busbars are respectively connected to the AC busbars; the first section of the first DC busbar is connected to the residential DC load and a DC energy storage unit; the second section of the first DC busbar is connected to the An important load, the sensitive load and another DC energy storage unit; the second DC bus is connected to the industrial DC load and the electric vehicle charging station. The novel micro-grid topology provided by the present invention uses an AC busbar and two DC busbars to divide the entire power supply system, and separates the power load system in the microgrid, that is, the important loads and sensitive loads in the microgrid are charged with electric vehicles. Stations are isolated from each other to avoid the impact of power changes when large-scale electric vehicles are connected to the microgrid through electric vehicle charging stations, the startup and shutdown of electric vehicle charging stations, and the output of distributed power sources on the power quality of the microgrid, thereby affecting The normal operation of important loads and sensitive loads; the energy storage system is also used to compensate the power changes of the microgrid and reduce the impact on the AC and DC bus voltage. Therefore, using the new microgrid topology provided by the present invention, the AC and DC busbars are used to separate the power load system in the microgrid, which can reduce the impact of power quality degradation caused by the connection of large-scale electric vehicle charging stations, so as to protect the microgrid. Continuous and reliable power supply for important loads and sensitive loads.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a traditional microgrid;

Figure 2 is a waveform diagram of the influence of solar power on the AC bus voltage in a traditional microgrid;

Figure 3 is a waveform diagram of the influence of large-scale electric vehicle charging station access on the grid frequency in a traditional microgrid;

FIG. 4 is a schematic structural diagram of a novel microgrid topology for large-scale electric vehicles provided by an embodiment of the present invention;

5 is a waveform diagram of the impact of solar power fluctuations on the AC bus voltage in a new microgrid topology for large-scale electric vehicles provided by an embodiment of the present invention;

FIG. 6 is a waveform diagram of the impact of the access of a large-scale electric vehicle charging station on the frequency of the power grid in the new micro-grid topology for large-scale electric vehicles provided by the embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a multi-microgrid structure based on a new microgrid topology for large-scale electric vehicles provided by an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

As shown in Figure 1, a traditional microgrid is mainly composed of an AC busbar, distributed power sources (micro gas turbines, solar generators, wind power), energy storage systems (DC energy storage, AC energy storage) and power load systems (including sensitive load and important load). All distributed power sources, energy storage systems and power load systems are connected to the AC bus, and fluctuations in distributed power sources and power load systems will affect the power quality of the microgrid.

The fluctuation of distributed power output will directly affect the power quality of the power load system. As shown in Figure 2, assuming that the solar power changes at 0.2s, the bus voltage is affected by it, and the amplitude fluctuates. For sensitive loads, such situations are not allowed. For important loads, the power supply reliability of traditional microgrids needs to be improved.

After large-scale electric vehicles are connected, the above-mentioned impact will be further increased. As shown in Figure 3, it is the waveform diagram of the influence of large-scale electric vehicle charging station access on the grid frequency under the traditional microgrid. Analysis of the waveform diagram shows that when the charging station is connected at 0.5s, the grid frequency drops to 49.88Hz, which can no longer meet the power grid frequency. quality requirements.

Therefore, aiming at the above-mentioned shortcomings of the traditional micro-grid, the present invention proposes a novel micro-grid topology for large-scale electric vehicles, and its specific implementation is as follows.

Please refer to Figure 4, the embodiment of the present invention provides a new microgrid topology for large-scale electric vehicles, including: AC bus, first DC bus, second DC bus, power load system, energy storage system , distributed power supply and electric vehicle charging station, among which,

The energy storage system includes an AC energy storage unit and two DC energy storage units; the power load system includes DC loads, AC loads, sensitive loads and important loads; the DC loads include industrial DC loads and residential DC loads;

The AC bus is connected to the distribution network through a transformer and a main switch;

The new micro-grid topology provided by the present invention is used to reduce the impact on the micro-grid caused by large-scale electric vehicles connected to the micro-grid through electric vehicle charging stations, or the start and stop of large-scale AC loads, and the output of distributed power sources. In order to ensure the long-term power supply of important loads in the microgrid and the continuous and reliable power supply of sensitive loads.

Among them, the distribution network is connected to the AC busbar through the transformer and the main switch in turn, and the electric energy output from the distribution network is transmitted to the AC busbar after adjusting the output voltage through the transformer.

The energy storage system is used to compensate the fluctuation of distributed power generation power when the access of large-scale electric vehicles affects the microgrid, so as to reduce the impact on the stability of the AC bus voltage. In actual situations, when the electric vehicle charging station is started or during the peak charging period, there may be a power shortage in the microgrid, which will affect the frequency of the microgrid. At this time, the energy storage system can be used to release electric energy to make up for the power shortage in the microgrid. , so as to reduce the influence of the electric vehicle charging station on the frequency of the microgrid and improve the power quality, which is of great significance. Wherein, the energy storage system in the embodiment of the present invention is a storage battery, and the energy storage system may also be other energy storage components, which are not specifically limited in the present invention.

Using the new micro-grid topology provided by the present invention, the waveform diagram of the impact of solar power fluctuations on the AC bus voltage after the energy storage system is compensated is shown in Figure 5. The lower line in the figure is the output power curve of the energy storage system. It is used to compensate the fluctuation of solar power generation power. It can be seen from the figure that the new micro-grid topology provided by the present invention can effectively ensure the stability of the AC bus voltage.

The power load system is the load connected to the microgrid, which can be external equipment, residential loads or industrial loads, etc., mainly including DC loads, AC loads, sensitive loads and important loads; for the loads or equipment in the microgrid, if the voltage occurs The load that changes or suddenly changes and causes it to fail to work or decline in function is called a sensitive load. Sensitive loads have high requirements for power supply quality; and important loads have a higher power supply level in the power system and are also important for industrial production or life. Affected loads, important loads are very sensitive to the power quality provided by the distribution network, so unreasonable power outages of the distribution network are not allowed, and long-term power supply is required.

The distributed power supply, the AC energy storage unit and the AC load are respectively connected to the AC bus;

The AC busbar is the main form of the current power system; the distributed power supply is connected to the AC busbar, which is beneficial to the centralized output adjustment of the energy storage system; the distributed power supply is used to convert primary energy into primary AC power. In the embodiment of the present invention, the distributed Type power sources include wind generators, solar generators and micro gas turbines; if the distributed power source is a wind generator, it can convert wind energy into electrical energy; if the distributed power source is a solar generator, it can convert solar energy into electrical energy; When the conventional power source is a micro gas turbine, it can convert thermal energy into electrical energy. The distributed power supply may also be other devices, which are not specifically limited in this embodiment of the present invention.

The AC energy storage unit is used in conjunction with the distributed power supply, and the AC energy storage unit is used to store the electric energy converted by the distributed power supply; when a large-scale electric vehicle is connected to the microgrid and affects the power of the distribution network, the AC energy storage unit is used To compensate the fluctuation of distributed power generation power, to reduce the impact of power fluctuation on AC bus voltage.

AC loads include residential AC loads and industrial AC loads. Both residential AC loads and industrial AC loads are connected to the AC bus to avoid being affected by DC bus power fluctuations.

The first DC bus and the second DC bus are respectively connected to the AC bus;

The novel microgrid topology provided by the present invention includes two DC buses, namely the first DC bus and the second DC bus, both of which are connected to the AC bus, and the AC bus and the two DC buses supply power to the whole The system is partitioned to isolate the loads in the power supply system that require high power quality, that is, important loads and sensitive loads, from the electric vehicle charging station, so as to prevent large-scale electric vehicles from connecting to the microgrid through the electric vehicle charging station. The start-up and shutdown of electric vehicle charging stations will affect the power quality of the microgrid, which will affect the normal operation of important loads and sensitive loads.

The first DC bus includes a first segment of the first DC bus and a second segment of the first DC bus;

The first section of the first DC bus is connected to the DC load of the residents and a DC energy storage unit;

The first DC bus in the second section is connected with the important load, the sensitive load and another DC energy storage unit;

The first DC bus is composed of the first section of the first DC bus and the second section of the first DC bus; the residents' DC load and a DC energy storage unit are connected to the first section of the first DC bus, and the important load, Sensitive loads and another DC energy storage unit are connected to the second section of the first DC bus.

Residential DC loads are used in conjunction with DC energy storage units. When the power in the distribution network fluctuates, the DC energy storage units can be used to compensate power to ensure the stability of the DC bus voltage. Important loads are used in conjunction with DC energy storage units, and are connected to the distribution network through tie lines and tie switches to improve power supply reliability.

The second DC bus is connected to the industrial DC load and the electric vehicle charging station.

Connecting industrial DC loads and electric vehicle charging stations to the second DC bus and connecting them to a different DC bus from sensitive loads can prevent fluctuations in the output power of distributed power sources and the startup and shutdown of industrial DC loads. affect the power quality.

The electric vehicle charging station is connected to the DC bus to centrally process the reactive power or harmonics of the electric vehicle and prevent it from affecting the microgrid.

Connect the power load that may generate reactive power or harmonics to the DC bus, and use the DC bus to eliminate reactive power or harmonics to prevent them from affecting the power quality of the microgrid.

Using the new micro-grid topology provided by the present invention, when a large-scale electric vehicle is connected through an electric vehicle charging station, the waveform diagram of the influence on the frequency of the micro-grid is shown in Figure 6 . It can be seen from the figure that due to the power compensation of the energy storage system and the separation of the AC and DC buses, the impact on the frequency of the micro-grid when the electric vehicle charging station is connected is reduced. The minimum frequency is 49.965HZ, which is within the safe operation range . The rated frequency of my country's power system is 50Hz, and the frequency deviation range is generally between -0.2Hz and 0.2Hz, that is, within the normal operating range of 49.8Hz to 50.2Hz.

It can be seen from the above technical solutions that the embodiment of the present invention provides a new micro-grid topology for large-scale electric vehicles, including: AC bus, first DC bus, second DC bus, power load system, energy storage system, a distributed power supply, and an electric vehicle charging station; the distributed power supply, the AC energy storage unit, and the AC load are respectively connected to the AC bus; the first DC bus and the second DC The busbars are respectively connected to the AC busbars; the first section of the first DC busbar is connected to the residential DC load and a DC energy storage unit; the second section of the first DC busbar is connected to the An important load, the sensitive load and another DC energy storage unit; the second DC bus is connected to the industrial DC load and the electric vehicle charging station. The novel micro-grid topology provided by the present invention uses an AC busbar and two DC busbars to divide the entire power supply system, and separates the power load system in the microgrid, that is, the important loads and sensitive loads in the microgrid are charged with electric vehicles. Stations are isolated from each other to avoid the impact of power changes when large-scale electric vehicles are connected to the microgrid through electric vehicle charging stations, the startup and shutdown of electric vehicle charging stations, and the output of distributed power sources on the power quality of the microgrid, thereby affecting The normal operation of important loads and sensitive loads; the energy storage system is also used to compensate the power changes of the microgrid and reduce the impact on the AC and DC bus voltage. Therefore, using the new microgrid topology provided by the present invention, the AC and DC busbars are used to separate the power load system in the microgrid, which can reduce the impact of power quality degradation caused by the connection of large-scale electric vehicle charging stations, so as to protect the microgrid. Continuous and reliable power supply for important loads and sensitive loads.

Preferably, the new microgrid topology structure further includes: a tie line, the tie line is used to connect the distribution network and the first DC bus bar of the second section, and the tie line is used for if the power in the microgrid When there is a shortage, the distribution network directly provides electric energy for the sensitive load and the important load through the connection line; and/or, the connection line is used to connect the electric vehicle charging station and the AC bus.

In the new microgrid topology, there are also two tie lines, one of which is connected to the distribution network and the first DC bus of the second section at both ends, and the first DC bus of the second section is connected to a sensitive Loads, important loads and DC energy storage units, so that the distribution network can be directly connected with sensitive loads and important loads through the connection line; the two ends of the other connection line are respectively connected to the electric vehicle charging station and the AC bus, and the electric vehicle charging station is Connected to the DC bus, so that the electric vehicle charging station can be directly connected to the AC bus through the connecting line.

When the distribution network system is running normally, the connection line is disconnected, and when necessary, the connection line is connected; in practical applications, when the distribution network fails and the microgrid switches to the island operation mode, and when When large-scale electric vehicles are connected to the microgrid through electric vehicle charging stations, when the power supply quality and power of the distribution network are abnormal, the distribution network needs to directly supply power to sensitive loads and important loads. Therefore, the first contact The line can be directly powered by the distribution network. When the distribution network reaches the peak period of power consumption, the energy storage system installed in the microgrid will be in a situation of power supply shortage. At this time, the second connection line can be connected to realize the direct connection of the electric vehicle charging station to the AC bus. To provide electric energy to the micro-grid, and at this time the electric vehicle will be used as an energy storage element, so that the scale of the energy storage system in the micro-grid can be reduced to reduce the construction cost of the micro-grid.

Preferably, the novel microgrid topology further includes: a backup power supply connected to the second DC bus.

The backup power supply is used to turn on the backup power supply and continue to provide power for the microgrid when the power provided by the distributed power supply in the distribution network reaches the maximum limit. The standby power supply in this embodiment is an internal combustion engine, and the standby power supply may also be other equipment, which is not specifically limited in the present invention.

Preferably, the novel microgrid topology further includes: several rectifiers, several choppers, several inverters and several frequency converters;

The rectifier is arranged between the AC bus and the distributed power supply and between the second DC bus and the AC bus; the chopper is respectively arranged between the residential DC load and the first Between the first DC bus, between the industrial DC load and the second DC bus, between the DC energy storage unit and the first DC bus, between the electric vehicle charging station and the between the second DC bus and between the backup power supply and the second DC bus; the inverter is arranged between the AC load and the AC bus, and between the first DC bus and the Between the AC buses, between the sensitive load and the first DC bus, and between the important load and the first DC bus; the frequency converter is set between the distributed power supply and the AC between the busbars and between the AC energy storage and the AC busbars.

Rectifiers are used to convert alternating current into specific forms of direct current; choppers are used to convert direct current into specific forms of direct current, such as converting distributed power output direct current into specific direct current for grid connection; inverters are used to convert direct current into specific forms AC power, such as converting distributed power output DC power into grid-connected AC power; frequency converters are used to convert AC power into specific forms of AC power.

Preferably, the novel microgrid topology further includes several tie switches: each of the tie switches is respectively arranged between the rectifier and the AC bus, and between the chopper and the first DC bus. between the chopper and the second DC bus, between the inverter and the AC bus, between the inverter and the AC bus, and between the first section of the first straight line Between the flow bus and the first DC bus of the second section.

A tie switch is set on each line connected to the AC bus or DC bus. When the distribution network is in normal operation, only when the tie switch is closed, the equipment on this line can work normally; The tie switch on the tie line is in the open state under normal conditions, and the tie switch is turned off only when needed.

According to another embodiment of the present invention, as shown in FIG. 7 , multiple new microgrid topology structures provided by the present invention are connected to form a multi-microgrid structure based on AC and DC buses. When the distribution network fails, the microgrid enters the island operation mode, and the active power (reactive power) in each microgrid may be unbalanced. Therefore, it can be considered to interconnect each new microgrid topology through a tie switch to achieve re-use. structure purpose.

Reconfiguration refers to that when the distribution network fails, each microgrid in a certain area enters an island operation state. If there is a power shortage or power surplus in the power grid, a micro-grid is reconstructed by connecting each micro-grid to achieve a power balance and reduce the application of energy storage.

Therefore, adopting the novel microgrid topology provided by the present invention is beneficial to the interconnection of multiple microgrids, and effectively solves the problem of microgrid reconfiguration after a distribution network failure.

It can be seen from the above technical solutions that the embodiment of the present invention provides a new micro-grid topology for large-scale electric vehicles, including: AC bus, first DC bus, second DC bus, power load system, energy storage system, a distributed power supply, and an electric vehicle charging station; the distributed power supply, the AC energy storage unit, and the AC load are respectively connected to the AC bus; the first DC bus and the second DC The busbars are respectively connected to the AC busbars; the first section of the first DC busbar is connected to the residential DC load and a DC energy storage unit; the second section of the first DC busbar is connected to the An important load, the sensitive load and another DC energy storage unit; the second DC bus is connected to the industrial DC load and the electric vehicle charging station. The novel micro-grid topology provided by the present invention uses an AC busbar and two DC busbars to divide the entire power supply system, and separates the power load system in the microgrid, that is, the important loads and sensitive loads in the microgrid are charged with electric vehicles. Stations are isolated from each other to avoid the impact of power changes when large-scale electric vehicles are connected to the microgrid through electric vehicle charging stations, the startup and shutdown of electric vehicle charging stations, and the output of distributed power sources on the power quality of the microgrid, thereby affecting The normal operation of important loads and sensitive loads; the energy storage system is also used to compensate the power changes of the microgrid and reduce the impact on the AC and DC bus voltage. Therefore, using the new microgrid topology provided by the present invention, the AC and DC busbars are used to separate the power load system in the microgrid, which can reduce the impact of power quality degradation caused by the connection of large-scale electric vehicle charging stations, so as to protect the microgrid. Continuous and reliable power supply for important loads and sensitive loads.

Other embodiments of the invention will be readily apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present invention, these modifications, uses or adaptations follow the general principles of the present invention and include common knowledge or conventional technical means in the technical field not disclosed in the present invention . The specification and examples are to be considered exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It should be understood that the present invention is not limited to the precise constructions which have been described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims (9)

1. A novel micro-grid topology for large-scale electric vehicles, characterized in that it comprises: an AC busbar, a first DC busbar, a second DC busbar, a power load system, an energy storage system, a distributed power supply and Electric vehicle charging stations, of which, The energy storage system includes an AC energy storage unit and two DC energy storage units; The power load system includes DC loads, AC loads, sensitive loads and important loads; The DC loads include industrial DC loads and residential DC loads; The AC bus is connected to the distribution network through a transformer and a main switch; The distributed power supply, the AC energy storage unit and the AC load are respectively connected to the AC bus; The first DC bus and the second DC bus are respectively connected to the AC bus; The first DC bus includes a first segment of the first DC bus and a second segment of the first DC bus; The first section of the first DC bus is connected to the residential DC load and a DC energy storage unit; The first DC bus in the second section is connected with the important load, the sensitive load and another DC energy storage unit; The second DC bus is connected to the industrial DC load and the electric vehicle charging station. 2. The new micro-grid topology structure for large-scale electric vehicles according to claim 1, further comprising: a tie line, the tie line is used to connect the distribution network and the second section The first DC bus, the connection line is used to directly provide electric energy for the sensitive load and the important load through the distribution network through the connection line if there is a power shortage in the microgrid; and/or , the connection line is used to connect the electric vehicle charging station and the AC bus. 3. The novel micro-grid topology structure for large-scale electric vehicles according to claim 1, further comprising: a backup power supply connected to the second DC bus. 4. The novel microgrid topology structure for large-scale electric vehicles according to claim 1, further comprising: several rectifiers, several choppers, several inverters and several frequency converters; The rectifier is arranged between the AC bus and the distributed power supply and between the second DC bus and the AC bus; The choppers are respectively arranged between the residential DC load and the first DC bus bar of the first section, between the industrial DC load and the second DC bus bar, and between the DC energy storage unit and the first DC bus bar. Between the first DC bus, between the electric vehicle charging station and the second DC bus, and between the backup power supply and the second DC bus; The inverter is arranged between the AC load and the AC bus, between the first DC bus and the AC bus, between the sensitive load and the first DC bus, and between the between the important load and the first DC bus; The frequency converter is arranged between the distributed power supply and the AC bus and between the AC energy storage unit and the AC bus. 5. The new micro-grid topology structure for large-scale electric vehicles according to claim 1, characterized in that it also includes several tie switches: each of the tie switches is respectively arranged on the rectifier and the AC bus between the chopper and the first DC bus, between the chopper and the second DC bus, between the inverter and the AC bus, the frequency conversion Between the inverter and the AC bus and between the first section of the first DC bus and the second section of the first DC bus. 6. The new micro-grid topology structure for large-scale electric vehicles according to claim 1, wherein the distributed power sources include: wind power generators, solar power generators and micro gas turbines. 7. The novel micro-grid topology structure for large-scale electric vehicles according to claim 1, wherein the AC loads include: industrial AC loads and residential AC loads. 8. The novel micro-grid topology for large-scale electric vehicles according to claim 3, wherein the backup power source is an internal combustion engine. 9. The new micro-grid topology for large-scale electric vehicles according to claim 1, wherein the energy storage system is a storage battery.