CN205489571U - Little grid system of high reliability based on centralized ring bus structure - Google Patents

Abstract

The utility model discloses a high-reliability micro-grid system based on a centralized ring-shaped busbar structure, including a public grid unit, a hybrid energy storage unit, a distributed power supply unit, a sub-microgrid unit and a ring-shaped first-level direct-current busbar. Each unit of the system is connected to the ring-shaped first-level DC bus. Each unit controls the power exchange through the corresponding converter. The hybrid energy storage system can stabilize the system power fluctuations and maintain the stability of the DC bus. The sub-DC microgrid is equipped with 380V The ring-shaped secondary DC bus and the 48V ring-shaped three-stage DC bus. The sub-AC microgrid is equipped with a 220V ring-shaped secondary AC bus, which can realize the direct power supply of high and low voltage loads. Each sub-microgrid constitutes a multi-ring bus. AC-DC hybrid interactive microgrid power supply area. The utility model can improve the power supply reliability, economy and diversity of the micro-grid system, and realize renewable energy.

Description

High Reliability Microgrid System Based on Centralized Ring Bus Structure

technical field

The utility model relates to a new energy micro grid system. In particular, it relates to a high-reliability microgrid system including hybrid energy storage, ring busbars and sub-AC/DC microgrids.

Background technique

In recent years, with the development of the economy and the advancement of science and technology, the energy crisis and environmental problems have become more and more prominent, and have gradually attracted the attention and attention of the country and people. It is necessary to find ways to widely apply renewable energy to replace fossil fuels as soon as possible. consumption is the only way for people's sustainable development. At the same time, with the improvement of people's living standards, electricity consumption has increased year by year, resulting in the power system showing the characteristics of increasing electricity load and gradually increasing transmission capacity. However, the current large-capacity centralized power generation and long-distance high-voltage transmission The problems of high operating costs, difficult operation, and weak regulation ability of the large interconnected power grid have become increasingly prominent, and it is difficult to meet the increasingly high safety, reliability, diversity, and flexibility power supply needs of users. With the continuous maturity of new power electronics technology, distributed power generation technology based on wind, light, heat, storage and other green energy sources is booming. Distributed power generation has the advantages of high energy utilization rate, low environmental pollution, strong power supply flexibility, and low input cost. The development and utilization of efficient and economical distributed power generation technology is an effective way to solve energy crisis and environmental problems.

Distributed power sources dominated by renewable energy have obvious intermittency, randomness and volatility. When a large-scale distributed power source is connected to a large power grid alone, it will have a great impact on the large power grid. Therefore, large power grids often isolate distributed power sources, so that the advantages of distributed power sources cannot be fully utilized, and renewable energy cannot be used efficiently. In order to alleviate the impact of large-scale distributed power single-unit network access on the large power grid, to make up for the lack of power system's extensive penetration and carrying capacity of distributed power, and to give full play to the advantages of distributed power generation technology, the concept of micro-grid came into being. Microgrid is an intensive new power network with independent management, protection and control capabilities composed of distributed power sources, load units and energy storage devices according to a specific topology. A multi-constraint, multi-state, multi-dimensional autonomous power system dominated by The microgrid has two operating modes: grid-connected and islanded, and can switch smoothly and seamlessly between the two modes. Generally, it is connected to the main grid through a single point, and has "plug and play" flexibility and controllability. An important part of the smart grid of the future. When the micro-grid is in the grid-connected mode, it can realize the integrated and coordinated operation of the public grid, distributed power sources and loads, and the cascade efficient utilization of various energy resources; when the large power grid fails, the micro-grid enters the island mode through decoupling control , to supply power to sensitive loads alone, fully meeting the user's needs for power supply security and reliability.

In order to cope with the severe challenges faced by the utilization of distributed power sources in terms of power supply quality, continuity, and stability, an efficient and reliable energy storage system is a guarantee for the normal operation of a micro-grid dominated by new energy sources and low-inertia power electronic devices. . The application of energy storage system in microgrid is as follows: 1) Through reasonable and orderly energy storage system control strategy, it can make up for the randomness, intermittent and uncontrollable defects of distributed power generation, and enhance the stability and dispatchability of distributed power generation ; 2) Charging when the load is low and discharging when the load is peak, as a micro-grid energy buffer link to realize load shaving and valley filling, improving the economy and reliability of the micro-grid; 3) Based on the fast response characteristics of the energy storage system, Slow down the transient impact of mode switching transition, realize the seamless and smooth switching of microgrid, and provide voltage and frequency support for the island operation of microgrid; 4) provide active power support or reactive power compensation for microgrid, and smooth the voltage fluctuation of microgrid , to improve the power quality of the microgrid.

The current micro-grid is in its infancy, and there are relatively few types of micro-grid architectures. The commonly used micro-grids are mostly radial busbar structures. The power supply form in the micro-grid is relatively single, resulting in a comparison of economy and stability. Difference. At the same time, a single type of energy storage device can no longer meet the development requirements of the microgrid, and the hybrid energy storage system will gradually replace the single energy storage device in the microgrid. In addition, with the development of the economy and the improvement of people's living standards, more and more equipment has been put into use. People have higher and higher requirements for power supply diversity and reliability, and more power supply forms and structures are required. .

Contents of the invention

The technical problem to be solved by the utility model is to provide a high-reliability microgrid system based on a centralized ring-shaped busbar structure. Each unit in the system is connected to the ring-shaped first-level DC busbar, and the sub-microgrid includes a ring-shaped The multi-ring bus of the AC bus and the ring DC bus greatly improves the diversity and reliability of the power supply of the microgrid. Through the ability of the hybrid energy storage system to stabilize the power, the quality of the power supply is improved, and the bidirectional converters are used to realize various The power exchange between units improves the interaction of each unit in the microgrid.

The technical scheme adopted by the utility model is: including a public power grid unit, a hybrid energy storage unit, a distributed power supply unit, a sub-microgrid unit and a ring-shaped first-level DC bus, wherein: the public power grid unit is connected to a public power grid A transformer, the other side of the transformer is correspondingly connected to a first bidirectional AC-DC (AC-DC) converter, and the other side of the first bidirectional AC-DC (AC-DC) converter is connected to the ring-shaped primary DC bus ; The hybrid energy storage unit, the hybrid energy storage system is connected to a primary bidirectional direct current-direct current (DC-DC) converter, and the other side of the primary bidirectional direct current-direct current (DC-DC) converter is correspondingly connected to a ring-shaped on the level DC bus; the distributed power unit includes fuel cells, photovoltaic cells, micro-gas turbines and wind generators, wherein the fuel cells and photovoltaic cells are each converted by a first direct current-direct current (DC-DC) The transformer is connected to the ring-shaped primary DC bus, and the micro-gas turbine and the wind generator are respectively connected to the ring-shaped primary DC bus through an AC-DC (AC-DC) converter; the sub-microgrid unit, It includes a sub-DC microgrid, a sub-AC microgrid, a first bidirectional direct current-direct current (DC-DC) converter and a bidirectional alternating current-alternating current (AC-AC) converter, wherein each sub-DC microgrid is connected by a first bidirectional direct current - Direct current (DC-DC) converter connection, each sub-AC microgrid is connected through a bidirectional AC-AC (AC-AC) converter, and each sub-DC microgrid and each sub-AC microgrid are connected at the ring level at the same time On the DC bus, thus forming a ring power supply architecture.

The hybrid energy storage system includes a first secondary bidirectional DC-DC (DC-DC) converter, a second secondary bidirectional DC-DC (DC-DC) converter, a storage battery and a supercapacitor, wherein the first secondary One side of the bidirectional direct current-direct current (DC-DC) converter and the second secondary bidirectional direct current-direct current (DC-DC) converter are respectively connected to the battery and the super capacitor, and the other side is connected to the primary bidirectional direct current-direct current in parallel (DC-DC) converter.

The sub-DC microgrid includes a ring-shaped secondary DC bus connected to the ring-shaped primary DC bus through a second bidirectional DC-DC (DC-DC) converter, a unidirectional DC-DC (DC-DC) The DC) converter is connected to the ring-shaped three-level DC bus on the ring-shaped two-level DC bus, the low-voltage DC load connected to the ring-shaped three-level DC bus through the second DC-DC (DC-DC) converter, and through the DC - Alternating current (DC-AC) converter is connected to the low-voltage AC load, storage battery, photovoltaic cell, fuel cell on the ring-shaped three-stage DC bus, and is connected to the ring-shaped second stage through the third direct current-direct current (DC-DC) converter The high-voltage DC load on the DC bus, in which the photovoltaic cell and the fuel cell are respectively connected to the ring-shaped secondary DC bus through the fourth DC-DC (DC-DC) converter, and the battery is connected to the ring-shaped secondary DC bus through the third bidirectional DC-DC (DC-DC) converter. The DC) converter is connected to the ring-shaped secondary DC bus.

The sub-AC microgrid includes a ring-shaped secondary AC bus connected to the ring-shaped primary DC bus through a bidirectional DC-AC (DC-AC) converter, a storage battery, a wind power generator, a micro-gas turbine, and a An AC-AC (AC-AC) converter is connected to the high-voltage AC load on the ring-shaped secondary AC bus, wherein the wind generator and the micro-gas turbine are respectively connected to each other through the second AC-AC (AC-AC) converter On the ring-shaped secondary AC bus, the storage battery is connected to the ring-shaped secondary AC bus through a second bidirectional AC-DC (AC-DC) converter.

The first bidirectional DC-DC (DC-DC) converter is connected between the ring-shaped secondary DC buses of the two sub-DC microgrids, and the bidirectional AC-AC (AC-AC) converter is connected between the two sub-AC microgrids. between the ring-shaped secondary AC buses of the power grid.

The utility model provides a high-reliability micro-grid system based on a centralized ring-shaped busbar structure, and its beneficial effects are: realizing the orderly operation of distributed power sources and the efficient cascade utilization of renewable energy, alleviating the pressure of environmental pollution and energy crisis; A hybrid energy storage system composed of batteries and supercapacitors is used to stabilize power fluctuations and improve power supply quality; the hybrid energy storage system adopts a two-level controller to increase power dispatchability; the sub-DC microgrid and sub-AC microgrid are used to form a ring-shaped microgrid. In the power supply area of the grid, the power exchange between each sub-microgrid can be carried out through the corresponding converter, thereby improving the interaction and flexibility of the system; a three-level bus connection method is adopted, including a ring-shaped first-level DC bus and a ring-shaped second-level DC bus. The DC bus, the ring-shaped secondary AC bus and the ring-shaped tertiary DC bus can improve energy utilization efficiency through the reasonable setting of each micro-power supply and load; the sub-microgrids are all ring-shaped structures, which can improve the reliability of power supply. The sub-microgrid unit combines the hybrid energy storage unit and the distributed grid unit to form an interactive microgrid power supply area with a multi-ring busbar AC and DC hybrid, which improves the economy of the system.

Description of drawings

Figure 1 is a schematic structural diagram of a high-reliability microgrid system based on a centralized ring bus structure;

Fig. 2 is a schematic structural diagram of a sub-DC microgrid and a sub-AC microgrid;

Fig. 3 is a schematic structural diagram of a hybrid energy storage system;

Fig. 4 is a schematic structural diagram of the connection mode between sub-microgrids.

in the picture

1: Public grid unit 2: Hybrid energy storage unit

3: Distributed power supply unit 4: Sub-microgrid unit

5: Ring primary DC bus 11: Public power grid

12: Transformer 13: First bidirectional AC-DC converter

21: Hybrid Energy Storage System 22: Primary Bidirectional DC-DC Converter

31: Fuel cell 32: Photovoltaic cell

33: micro-combustion engine 34: wind power generator

35: First DC-DC Converter 36: First DC-DC Converter

37: AC-DC Converter 38: AC-DC Converter

41: Sub-DC microgrid 42: Sub-AC microgrid

43: First bidirectional DC-DC converter 44: Bidirectional AC-AC converter

detailed description

The high-reliability microgrid system based on the centralized ring bus structure of the present invention will be further described below in conjunction with the accompanying drawings.

The high-reliability micro-grid system based on the centralized ring-shaped bus structure of the utility model forms a multi-micro-grid through the centralized ring-shaped DC bus, distributed power supply, hybrid energy storage system, sub-DC micro-grid and sub-AC micro-grid Interactive AC-DC hybrid microgrid system. The system is equipped with three levels of buses, including ring-shaped first-level DC bus, ring-shaped second-level DC bus, ring-shaped second-level AC bus and ring-shaped three-level DC bus. The ring-shaped first-level DC bus is a high-voltage DC bus with a voltage level of 500V The busbar, the circular secondary DC busbar is a medium-voltage DC busbar with a voltage level of 380V, the circular secondary AC busbar is a medium-voltage AC busbar with a voltage level of 220V, and the circular three-level DC busbar is a low-voltage DC busbar with a voltage level of 48V Bus, through the setting of multi-level bus, so as to increase the functional diversity of the system and improve the power supply efficiency. A public grid unit, a hybrid energy storage unit, a distributed power supply unit and a sub-micro-grid unit are arranged on the ring-shaped primary DC bus, among which: the micro-grid system can control the grid-connected or islanded operation status through the on-off connection with the public grid unit; The hybrid energy storage unit can balance system power fluctuations through charge and discharge control, thereby maintaining the stability of the DC bus voltage; the distributed power supply unit includes micro-gas turbines and wind generators that output alternating current, fuel cells and photovoltaic cells that output direct current, so as to make full use of Renewable energy; the sub-DC microgrid and the sub-AC microgrid are connected to the ring-shaped first-level DC bus, and each sub-microgrid can also independently control the operating status of the system to improve the stability of power supply. The ring-shaped secondary DC bus and the ring-shaped secondary AC bus are respectively set in the sub-DC microgrid and the sub-AC microgrid. In order to increase the power supply efficiency of the system and improve the economy of the system, the photovoltaic cells and fuel cells that output DC are connected in the ring On the ring-shaped secondary DC bus, the wind turbine and the micro-turbine that output AC power are connected to the ring-shaped secondary AC bus. At the same time, batteries are installed on both buses to stabilize power fluctuations. A low-voltage AC load and a low-voltage DC load are connected to the ring-shaped three-level DC bus.

As shown in Figure 1, the high-reliability microgrid system based on the centralized ring busbar structure includes a public grid unit 1, a hybrid energy storage unit 2, a distributed power supply unit 3, a sub-microgrid unit 4, and a ring-shaped primary DC The bus bar 5, wherein: the public power grid unit 1, the public power grid 11 is connected to a transformer 12, and the other side of the transformer 12 is correspondingly connected to a first bidirectional AC-DC (AC-DC) converter 13, the first bidirectional AC- The other side of the DC (AC-DC) converter 13 is connected to the annular primary DC bus 5; the hybrid energy storage unit 2 and the hybrid energy storage system 21 are connected to a primary bidirectional direct current-direct current (DC-DC) Converter 22, the other side of the primary bidirectional DC-DC (DC-DC) converter 22 is correspondingly connected to the ring-shaped primary DC bus 5; the distributed power supply unit 3 includes a fuel cell 31, a photovoltaic cell 32 , a micro-combustion engine 33 and a wind generator 34, wherein the fuel cell 31 and the photovoltaic cell 32 are respectively connected to the ring-shaped primary DC bus 5 through a first direct current-direct current (DC-DC) converter 35/36, The micro-combustion turbine 33 and the wind generator 34 are respectively connected to the ring-shaped primary DC bus 5 through an AC-DC (AC-DC) converter 37/38; the sub-microgrid unit 4 includes a sub-DC micro Grid 41, sub-AC microgrid 42, first bidirectional direct current-direct current (DC-DC) converter 43 and bidirectional alternating current-alternating current (AC-AC) converter 44, wherein each sub-DC microgrid 41 is connected by the first bidirectional DC-DC (DC-DC) converters 43 are connected, each sub-AC microgrid 42 is connected through a bidirectional AC-AC (AC-AC) converter 44, and each sub-DC microgrid 41 and each sub-AC microgrid 42 are connected simultaneously It is connected to the ring-shaped primary DC bus 5 to form a ring-shaped power supply architecture.

The public grid unit 1, the hybrid energy storage unit 2, the distributed power unit 3 and the sub-microgrid unit 4 are all connected to the ring-shaped primary DC bus through a specific converter. Generator 34, fuel cell 31 and photovoltaic cell 32 that output direct current, wind power generation and photovoltaic power generation can form complementary, thereby improve the reliability of power supply, and when the output power of photovoltaic cell 32 and wind-driven generator 34 is insufficient, micro-combustion engine 33 And the fuel cell 31 can increase the power output to ensure the load power supply. When the microgrid is in the grid-connected mode, it can realize the integrated coordinated operation of the public grid unit 1, the distributed power supply unit 3 and the load and the cascade efficient utilization of various energy resources; when the public grid unit 1 fails, the microgrid passes through The decoupling control enters the island mode, and supplies power to the load independently, fully meeting the safety and reliability requirements of power supply. The hybrid energy storage unit 2 adopts a hybrid energy storage form composed of a battery with high energy density and a supercapacitor with high power density and long cycle life, so as to improve the power output capability and prolong the service life of the device. When the distributed power output power of the system is too large, the hybrid energy storage system 21 can absorb excess power; when the distributed power output power of the system is too small, the hybrid energy storage system 21 can make up for the power shortage, in which the battery 213 absorbs or emits low frequency power, the supercapacitor 214 absorbs or emits high-frequency power. Each micro power source in the distributed power source unit 3 determines the control strategy and controls the output power through the scheduling requirements of the system and the instructions of the local controller. The number of sub-DC microgrids 41 and sub-AC microgrids 42 in the system can be determined according to actual load conditions. When any sub-DC microgrid 41 or sub-AC microgrid 42 in the system fails, it can be isolated by decoupling control to ensure the safe power supply of other loads. When other parts of the system fail, the sub-DC microgrid 41 or the sub-AC microgrid 42 can also enter the island operation state through decoupling control, so as to ensure the power supply of loads in the system, thus improving the reliability, safety and flexibility of power supply.

As shown in Figure 2, the sub-DC microgrid and the sub-AC microgrid are schematically shown, and the sub-DC microgrid 41 includes a second bidirectional direct current-direct current (DC-DC) converter 414 connected in a ring-shaped one-stage DC A ring-shaped secondary DC bus 412 on the bus 5, a ring-shaped tertiary DC bus 411 connected to the ring-shaped secondary DC bus 412 through a unidirectional DC-DC (DC-DC) converter 413, and a second DC - The direct current (DC-DC) converter 4111 is connected to the low-voltage DC load 415 on the ring-shaped three-level DC bus 411, and the low-voltage DC load 415 connected to the ring-shaped three-level DC bus 411 through the direct current-alternating current (DC-AC) converter 4112 AC load 416, storage battery 417, photovoltaic cell 418, fuel cell 419, high-voltage DC load 4110 connected to the ring-shaped secondary DC bus 412 through a third direct current-direct current (DC-DC) converter 4116, wherein the photovoltaic cell 418 and the fuel cell 419 are respectively connected to the annular secondary DC bus 412 through the fourth direct current-direct current (DC-DC) converter 4114/4115, and the storage battery 417 is connected through the third bidirectional direct current-direct current (DC-DC) converter 4113 On the ring-shaped secondary DC bus 412 .

The sub-AC microgrid 42 includes a ring-shaped secondary AC bus 422 connected to the ring-shaped primary DC bus 5 through a bidirectional DC-AC (DC-AC) converter 421, a storage battery 423, a wind generator 424, The micro-combustion engine 425, the high-voltage AC load 426 connected to the annular secondary AC bus 422 through the first AC-AC (AC-AC) converter 4210, wherein the wind power generator (424) and the micro-combustion engine 425 respectively pass The second AC-AC (AC-AC) converter 428/429 is connected to the ring-shaped secondary AC bus bar 422, and the storage battery 423 is connected to the ring-shaped secondary AC bus bar 427 through the second bidirectional AC-DC (AC-DC) converter 427. on the bus 422.

The first-level DC busbar is a ring structure, and the topological forms of the sub-DC microgrid 41 and the sub-AC microgrid 42 are also ring-shaped. At the same time, each sub-DC microgrid 41 is connected by a first bidirectional direct current-direct current (DC-DC) converter 43 connections, the sub-AC microgrids 42 are connected through a bidirectional AC-AC (AC-AC) converter 44, and the sub-DC microgrids 41 and sub-AC microgrids 42 are respectively connected to the ring-shaped primary DC bus 5, so that each sub-microgrid The power grid constitutes an AC-DC mixed micro-grid ring power supply area, which can greatly improve the reliability of power supply. The setting of multi-level ring busbars increases the flexibility of power supply. Both the sub-DC microgrid 41 and the sub-AC microgrid 42 can directly supply power to low-voltage loads, and can also supply power to high-voltage DC loads 4110 and high-voltage AC loads 426 respectively. The battery in the sub-microgrid can balance the power fluctuations in the system and maintain the stability of the DC bus. The sub-DC microgrid 41 and the sub-AC microgrid 42 exchange power with other units through a second bidirectional direct current-direct current (DC-DC) converter 414 and a bidirectional direct current-alternating current (DC-AC) converter 421, respectively, in a circular one-stage The power flow between the DC bus 5 and the secondary DC bus 412 and the secondary AC bus 422 is bidirectional, and the power between each sub-microgrid, between the sub-microgrid and the microgrid, and between the microgrid and the public grid can flow bidirectionally. This greatly increases the interactivity of the system and improves the reliability of mutual support among the units.

In the hybrid energy storage system shown in Figure 3, one side of the first secondary bidirectional direct current-direct current (DC-DC) converter 211 and one side of the second secondary bidirectional direct current-direct current (DC-DC) converter 212 are respectively connected to The storage battery 213 and the supercapacitor 214 are connected in parallel to the primary bidirectional direct current-direct current (DC-DC) converter 22 on the other side. When power fluctuations occur in the system, the storage battery 213 absorbs or releases low-frequency power, the supercapacitor 214 absorbs or releases high-frequency power, and the primary bidirectional direct-current (DC-DC) converter 22 controls the overall power flow of the hybrid energy storage system 21, while The first secondary bidirectional direct-current (DC-DC) converter 211 and the second secondary bidirectional direct-current (DC-DC) converter 212 respectively control the power flow of the storage battery 213 and the supercapacitor 214, through two-stage control The setting of the device increases the power schedulability.

As shown in FIG. 4, the connection mode between each sub-microgrid, the first bidirectional DC-DC (DC-DC) converter 43 is connected between the ring-shaped secondary DC buses 412 of the two sub-DC microgrids 41, A bidirectional alternating current-alternating current (AC-AC) converter 44 is connected between the ring-shaped secondary AC busbars 422 of the two sub-AC microgrids 42 . Each sub-DC microgrid 41 and sub-AC microgrid 42 can realize mutual support control through group power scheduling and group coordination control, and the multi-ring structure also improves the reliability of power supply.

Claims (5)

1. high reliability micro-grid system based on centralized ring bus structure, it is characterized in that, including public electric wire net unit (1), hybrid energy-storing unit (2), distributed power unit (3), sub-micro-capacitance sensor unit (4) and ring-type one-level dc bus (5), wherein:

Described public electric wire net unit (1), public electric wire net (11) connects a transformator (12), the opposite side correspondence of transformator (12) connects a first two-way exchange-direct current (AC-DC) changer (13), and the opposite side of the first two-way exchange-direct current (AC-DC) changer (13) is connected on ring-type one-level dc bus (5)；

Described hybrid energy-storing unit (2), mixed energy storage system (21) connects a primary two-way DC-DC (DC-DC) changer (22), and the opposite side correspondence of primary two-way DC-DC (DC-DC) changer (22) is connected on ring-type one-level dc bus (5)；

Described distributed power unit (3), including fuel cell (31), photovoltaic cell (32), miniature combustion engine (33) and wind-driven generator (34), wherein fuel cell (31) and photovoltaic cell (32) are all connected on ring-type one-level dc bus (5) each via first DC-to-dc (DC-DC) changer (35/36), and miniature combustion engine (33) and wind-driven generator (34) are all connected on ring-type one-level dc bus (5) each via an AC-DC (AC-DC) changer (37/38)；

Described sub-micro-capacitance sensor unit (4), including sub-direct-current grid (41), son exchange micro-capacitance sensor (42), first two-way DC-DC (DC-DC) changer (43) and two-way exchange-exchange (AC-AC) changer (44), connected by the first two-way DC-DC (DC-DC) changer (43) between the most each sub-direct-current grid (41), connected by two-way exchange-exchange (AC-AC) changer (44) between each sub-exchange micro-capacitance sensor (42), each sub-direct-current grid (41) is simultaneously connected with on ring-type one-level dc bus (5) with each sub micro-capacitance sensor (42) that exchanges, thus constitute looply connected power supply framework.

High reliability micro-grid system based on centralized ring bus structure the most according to claim 1, it is characterized in that, described mixed energy storage system (21) includes first level two-way DC-DC (DC-DC) changer (211), second subprime two-way DC-DC (DC-DC) changer (212), accumulator (213) and super capacitor (214), wherein the side of first level two-way DC-DC (DC-DC) changer (211) and second subprime two-way DC-DC (DC-DC) changer (212) is connected respectively accumulator (213) and super capacitor (214), opposite side mode in parallel connects primary two-way DC-DC (DC-DC) changer (22).

nullHigh reliability micro-grid system based on centralized ring bus structure the most according to claim 1，It is characterized in that，Described sub-direct-current grid (41) includes the ring-type two grades of dc bus (412) being connected on ring-type one-level dc bus (5) by the second two-way DC-DC (DC-DC) changer (414)、One ring-type three grades of dc bus (411) being connected on ring-type two grades of dc bus (412) by Unidirectional direct-current-direct current (DC-DC) changer (413)、It is connected to the low-voltage direct load (415) on ring-type three grades of dc bus (411) by the second DC-to-dc (DC-DC) changer (4111)、It is connected to the low-voltage alternating-current load (416) on ring-type three grades of dc bus (411) by DC-AC (DC-AC) changer (4112)、Accumulator (417)、Photovoltaic cell (418)、Fuel cell (419)、It is connected to the HVDC load (4110) on ring-type two grades of dc bus (412) by the 3rd DC-to-dc (DC-DC) changer (4116)，Wherein，Photovoltaic cell (418) and fuel cell (419) are connected on ring-type two grades of dc bus (412) by the 4th DC-to-dc (DC-DC) changer (4114/4115) respectively，Accumulator (417) is connected on ring-type two grades of dc bus (412) by the 3rd two-way DC-DC (DC-DC) changer (4113).

nullHigh reliability micro-grid system based on centralized ring bus structure the most according to claim 1，It is characterized in that，Described son exchange micro-capacitance sensor (42) includes the ring-type two grades of ac bus (422) being connected on ring-type one-level dc bus (5) by bidirectional, dc-exchange (DC-AC) changer (421)、Accumulator (423)、Wind-driven generator (424)、Miniature combustion engine (425)、It is connected to the high-voltage alternating load (426) on ring-type two grades of ac bus (422) by the first AC-AC (AC-AC) changer (4210)，Wherein，Wind-driven generator (424) and miniature combustion engine (425) are connected on ring-type two grades of ac bus (422) by the second AC-AC (AC-AC) changer (428/429) respectively，Accumulator (423) is connected on ring-type two grades of ac bus (422) by the second two-way exchange-direct current (AC-DC) changer (427).

High reliability micro-grid system based on centralized ring bus structure the most according to claim 1, it is characterized in that, described the first two-way DC-DC (DC-DC) changer (43) is connected between ring-type two grades of dc bus (412) of two sub-direct-current grid (41), and two-way exchange-exchange (AC-AC) changer (44) is connected between ring-type two grades of ac bus (422) of two sons exchange micro-capacitance sensor (42).