CN105226717A - Micro-grid connection system in urban distribution network - Google Patents

Abstract

The present invention provides a grid-connected micro-grid system in an urban power grid, in which a diesel generator system or a gas turbine that provides stable output power is used to provide power for AC loads connected to the same feeder, and a wind-solar storage system is used as an auxiliary power supply ;Cooling and heating are provided by the joint-supply synchronous units including gas turbines, and the AC loads of the same feeder are powered; the DC loads connected to the same DC bus are powered by distributed power sources, and the DC loads connected to the same DC bus are powered by the inverter, which is connected to the same AC The AC load of the bus is powered, and then connected to one of the feeders through another transformer to realize grid connection. The invention takes the grid-connected target and the supplied load as boundary conditions, and proposes a basic scheme of a micro-grid grid-connected system suitable for urban power grids, which has good engineering practicability.

Description

Microgrid grid-connected system in urban power grid

technical field

The invention relates to the field of power supply, in particular to a grid-connected micro-grid system in an urban power grid.

Background technique

my country's energy structure and load characteristics determine the development characteristics of the power industry in which the west and north are power generation bases, and the central and eastern parts are load centers. As a result, the transmission form connecting power generation bases and load centers through long-distance, large-capacity transmission channels has become the main transmission form in my country. However, when an accident occurs in this form, the accident is easy to spread, and it will cause greater pressure on the peak shaving problem of the load center. For large-scale and long-distance power transmission, peak regulation is difficult, so it can be solved from the perspective of demand side management. The flexible and convenient distributed power supply can become an important supplement to the long-distance and large-capacity power supply mode. However, the widespread use of new energy distributed power generation is severely restricted by natural factors, which directly lead to the concept of a micro-grid that combines distributed power sources, power loads, energy storage devices, and control devices.

In actual engineering, according to the different power sources of the micro-grid, the typical structure classification of the micro-grid, the location of the micro-grid, and the purpose of the construction, the final grid connection method of the micro-grid is also different. Typical power sources for microgrids are mainly divided into single power sources, wind-solar-storage combined power generation, micro gas turbines and combined power sources, and biomass micro-grids. Typical structures of microgrids include AC microgrid, DC microgrid, AC and DC microgrid

Among them, for some areas where the types of renewable energy are relatively single, local renewable energy is mainly used as the basic power supply of the micro-grid. At the same time, different energy storage and other auxiliary new energy sources are configured to meet different construction purposes. Generally speaking, areas with a single power source are mainly wind power and photovoltaics. The micro-grid based on wind power is mainly used in the west of my country, the north and other wind resources are class I or II, but relatively remote areas, mainly used to supply electricity to the local area, as an important supplement to the large power grid. In addition, the wind power-based micro-grids in the southeastern coastal provinces have small capacity and are often equipped with other energy sources such as photovoltaics and energy storage. They are mainly scientific research-based, generally adopt grid-connected type, and need the support of large power grids.

In order to solve the problem of no sunshine at night, the off-grid photovoltaic microgrid mainly meets the power demand at night by configuring energy storage equipment. Due to cost constraints, off-grid photovoltaic microgrids tend to provide relatively small loads and do not require high reliability of power supply. Grid-connected photovoltaic microgrids generally do not configure or configure energy storage in a small amount, and the purpose of configuration is mainly to improve power quality. The construction site is a city with a strong power grid, and it is often combined with buildings to avoid excessive land occupation. For example, grid-connected photovoltaic power generation systems are installed on the roofs of public facilities, commercial buildings, and industrial factories.

Wind-solar-storage combined power supply micro-grid refers to a micro-grid with photovoltaic power generation and wind power generation as the main functional form, which can combine the characteristics of wind power and photovoltaic power generation to form complementary advantages. For example, wind power tends to generate less power during the day and more power at night, while photovoltaics are the opposite. The combination of wind and wind can reduce the fluctuation of microgrid power supply to some extent. In order to reflect the wind-solar complementarity in a wider range and ensure that the power quality of the micro-grid meets other requirements, a certain amount of energy storage equipment needs to be configured. However, due to the configuration of a certain amount of energy storage devices, the cost of wind-solar-storage micro-grids is often high. In order to minimize the development pressure of high costs, this type of micro-grid is often located in areas where wind and solar resources are relatively good, the power market is relatively mature, and the economy is relatively high. Developed areas are developed as pilot projects. Cost factors limit the development potential of wind-solar-storage microgrids in general areas.

In the actual construction of a microgrid, in addition to power sources with a wide range of applications such as wind power storage and relatively low cost, there are also other types of power sources. At present, many cities in my country have developed industrial parks and high-tech parks, and these parks often have relatively stable demand for cooling and heating loads. Gas turbines have the characteristics of low unit power cost, environmental friendliness, and high energy utilization rate. Therefore, gas turbines have become the backbone of the park's combined cooling, heating, and power supply. By fully burning natural gas to drive the steam turbine to generate electricity, the exhaust gas is directly used for heating or the lithium bromide unit is used for refrigeration to meet the demand for cooling and heating loads and improve energy utilization. However, the main factor limiting gas turbines is the implementation of the gas source. my country's natural gas reserves are unevenly distributed, and the West-to-East Gas Pipeline Project has limited supply of natural gas to large and medium-sized cities in the east, and the price is often expensive. Therefore, gas turbine systems are currently used in fewer occasions, limited to large cities with relatively sufficient natural gas supply, and are generally grid-connected grids, which are only used to supply cooling and heating loads.

Biomass can be divided into many kinds, including wood chips, straw, biogas, domestic waste and so on. my country is rich in resources, and different regions are also suitable for different biomass energy. For example, in the northeastern region where forestry is more developed, leftover debris from logging can be used as raw materials for biomass power generation. The provinces with relatively developed agriculture in the central and eastern regions are suitable for using straw and grain processing residues as raw materials for biomass power generation. In the vast rural areas, it is suitable to develop biogas power generation from livestock and poultry breeding waste, and at the same time use biomass energy such as domestic waste and crop straw, and develop microgrids based on these energy supply systems.

The AC microgrid is still the mainstream of the microgrid at present. With the mature AC grid as the basic grid structure, the load and microgrid power distribution are carried out on the load side, which has become the prototype of the AC microgrid.

For the situation where there are many distributed power sources and the load is small, a DC microgrid can be selected. The use of DC microgrid can greatly reduce the large number of converters used in AC microgrid, so that the power in the distributed power supply can be directly absorbed by the DC load, with a simpler structure, less loss and higher efficiency.

The hybrid AC-DC microgrid is connected with the household AC network through the AC system, and connected with the DC microgrid through the inverter. This kind of microgrid structure is flexible and applicable to various loads. However, the microgrid structure is relatively complex, and the construction cost is relatively high.

It can be seen that the structure of the micro-grid is flexible and applicable to a wide range of applications. It is not possible to propose a grid-connected mode of the micro-grid only for a certain type of grid and load conditions. The micro-grid with different boundary conditions should be considered and combined according to the boundary conditions such as the surrounding grid, load type, or load demand. net program. Therefore, how to quickly and effectively select the appropriate grid-connected mode of the micro-grid is of great significance to improve the construction efficiency of the actual micro-grid project.

Contents of the invention

The invention provides a micro-grid grid-connected system in an urban power grid. Aiming at the situation that the urban grid is an external grid, according to different grid-connected targets and supplied loads, a typical grid-connected scheme of the micro-grid is proposed.

In order to achieve the above purpose, a technical solution of the present invention is to provide a microgrid grid-connected system in the urban power grid, which includes any of the following microgrids or Any combination of:

A diesel generator system or gas turbine that provides stable output power is used to supply power to the AC load of the same feeder after the diesel generator system or gas turbine is connected to the medium-voltage busbar, and the wind-solar-storage system is connected to the feeder as the Auxiliary power supply for the above-mentioned AC load;

The joint-generation synchronous unit including the gas turbine is responsible for cooling and heating the cooling and heating loads, and supplies power to the AC load of the same feeder after the joint-generation synchronous unit is connected to the medium-voltage busbar;

The distributed power supply is used to supply power to the DC loads connected to the same DC bus as the distributed power supply; the power supply on the DC bus is connected to an AC bus after passing through the inverter to supply power to the AC loads connected to the same AC bus; The power supply of the AC bus is connected to one of the feeders behind the medium voltage bus through another transformer.

Preferably, a micro-grid that uses a diesel generator system or a gas turbine to supply power to AC loads of the same feeder is set in an industrial park, and the micro-grid adopts an AC system and is integrated into the original power grid system.

Preferably, the power supply reliability requirements of the AC load powered by the wind-solar-storage system and the diesel generator system or gas turbine that provide stable output power in the same feeder are higher than those of other loads connected to another feeder.

Preferably, a gas turbine or biomass unit connected to the grid with an AC system is provided in the microgrid containing a diesel generator system or a gas turbine with stable output power; or, in the microgrid, the diesel generator system is replaced by a wind-solar storage system to supply power to the AC load.

Preferably, a micro-grid that uses a combined-supply synchronous unit including a gas turbine to provide cooling and heating and also provides power to the AC load of the same feeder is set in an industrial park or a high-tech park; the micro-grid uses an AC system to integrate into the original In the power grid system, any one or any combination of photovoltaic power plants, wind turbines, and energy-based energy storage devices at another feeder behind the medium-voltage bus provides auxiliary power supply for the AC loads connected to the other feeder; Another feeder after the medium-voltage bus is connected with a power-off load.

Preferably, a micro-grid with a co-generation synchronous unit containing a gas turbine responsible for cooling and heating, and taking into account the power supply for the AC load of the same feeder, is set in an industrial park or a high-tech park; When there is a power grid system, any one or any combination of photovoltaic power plants, wind turbines, and power-type energy storage devices provides auxiliary power supply for the DC load connected to the same DC bus as it is located in;

The power supply of the DC bus is connected to another feeder after the medium-voltage bus through the inverter and connected to the transformer, and supplies power to some interruptible loads connected to the other feeder; at another feeder after the medium-voltage bus There are other disconnectable loads connected.

Preferably, the power supply reliability requirement of the disconnectable load connected at another feeder behind the medium-voltage bus is lower than that of the AC load or DC load at other feeders.

Preferably, the micro-grid containing distributed power is set on the roofs of buildings or surrounding open spaces in urban areas, and the distributed power of the micro-grid includes: any one of a single power supply, a wind-solar-storage combined power supply, and a chemical fuel cell power supply. The single power source is a photovoltaic power source or a wind power source; the microgrid adopts an AC system and merges into the original grid system.

Preferably, any one of the photovoltaic power station, wind turbine, power-type energy storage device or a combination thereof supplies power to the DC load connected to the same DC bus as it is located; Other AC loads; an interruptible load is connected to another feeder behind the medium-voltage bus; the power supply reliability requirements of the DC loads are higher than those of other loads in the microgrid grid-connected system.

Another technical solution of the present invention is to provide a micro-grid grid-connected system in an urban power grid, which sequentially includes: a substation-level micro-grid, a feeder-level micro-grid, and a single/multi-user level micro-grid;

The substation-level micro-grid is provided with two switching stations, and each station is provided with two sections of first busbars, which are connected to the first transformer through corresponding public connection points to be integrated into the external power grid;

Some photovoltaic power stations of the single/multi-user level microgrid are connected to the second bus bar of this level through the corresponding feeder line of this level, and the second bus bar of this level is connected to the first bus bar of the corresponding switchyard through the second transformer. a bus;

Any one or any combination of the fan, energy storage system, diesel generator system, and other photovoltaic power plants of the single/multi-user level microgrid is connected to the same section of the third busbar of this level and is connected to the same section of the third bus through the rectifier. The DC load connected to the third bus is powered; the third bus is also connected to the corresponding feeder of the feeder-level microgrid through the third transformer of the feeder-level microgrid, and connected to the fourth bus through the feeder-level microgrid. Four transformers are connected to the first bus bar of the corresponding switching station;

The photovoltaic power station of the microgrid at the feeder level is selected to be connected to the feeder of this level through a switch, and then directly connected to the first bus of the corresponding switchyard through the fifth bus of this level, or to be connected to the The third busbar of the single/multi-user level microgrid of the single/multiple user level microgrid;

Any one or any combination of the gas turbine, internal combustion engine, and energy storage battery of the feeder-level microgrid is connected to the sixth busbar of this level, and the power supply of the sixth busbar passes through another switch, and the selection passes through the corresponding switch station The feeder is connected to the first bus, or is selected to be connected to the third bus of the single/multi-user level microgrid.

To sum up, on the basis of fully investigating microgrid laboratory systems and typical demonstration projects at home and abroad, this invention combines the characteristics of microgrid itself and my country's energy structure, and uses the typical power supply mode of microgrid to study and propose a microgrid-based The typical structure of the distributed wind-storage storage system, including network topology, electrical wiring network structure inside the micro-grid, power supply system (DC/AC power supply and three-phase/single-phase power supply), corresponding loads and the location of the micro-grid where the distributed power supply is located etc. The invention takes the grid-connected target and the supplied load as boundary conditions, and proposes a basic scheme of a micro-grid grid-connected system suitable for urban power grids, which has good engineering practicability.

Description of drawings

Fig. 1 is the schematic diagram of the micro-grid grid-connected system in the urban power grid of the present invention in scheme 1A;

Fig. 2 is the schematic diagram of the first embodiment in scheme 1B in the present invention;

Fig. 3 is the schematic diagram of the second embodiment of scheme 1B in the present invention;

Fig. 4 is the schematic diagram in scheme 1C among the present invention;

Fig. 5 is a schematic diagram of a grid-connected combination scheme of the present invention.

detailed description

In the present invention, based on the constraints of the different external power grids, with the grid-connected target and the supplied load as the boundary conditions, a typical grid-connected basic scheme for micro-grids suitable for different boundary conditions is proposed. In actual engineering, it can be based on the different needs of the owner. , combining various basic schemes.

The grid-connected target in the present invention is the urban power grid, including urban areas, surrounding suburbs, industrial parks, high-tech parks and other areas where the grid is relatively developed. In the region, different regions often have different original intentions for building microgrids, which can be generally divided into the following types:

(1) Improve power supply reliability. This kind of grid connection goal is often the most common, and there are often such requirements for the end areas of urban power grids, especially some light and heavy industrial loads located around cities. In this case, enterprises generally consider self-provided power plants or small power generation equipment. When the external power grid fails, the self-provided power plants start to supply power to the load.

(2) Adopt energy co-supply to improve energy utilization rate. This kind of grid connection target is more common in high-tech parks or industrial parks. In areas where this kind of grid-connected target is adopted, the distance between the cooling and heating loads is generally relatively close, and the cooling and heating loads are relatively clear. Under the condition that the grid supplies power to the loads, the combined power supply system can meet its own cooling and heating load needs on the one hand, and on the other hand On the one hand, energy efficiency can be improved, and the economy can be improved to a certain extent by relying on relevant policies.

(3) Use the microgrid to absorb distributed power, reduce electricity consumption or increase the added value of real estate. This kind of situation is widely used in urban areas or small-scale industrial factories, and roof construction is often used, which limits the capacity scale of this kind of micro-grid. Generally speaking, the form of this microgrid is changeable, and the characteristics of small capacity and multiple distribution points are more obvious.

The power grid structure involved in the present invention belongs to the area of urban power grid, generally cities, commercial areas, high-tech parks or light and heavy industrial areas, and the load types are mainly industrial and commercial loads, urban loads, etc.

For industrial loads, large volume and stability are its two most prominent features. In addition, for industrial parks and high-tech parks, industrial loads often coexist with commercial loads and residential loads. The power supply system in this kind of park is similar to the residential load, but compared with the residential load, the peak-to-valley difference of the load characteristics in the park is smaller, and the curve is gentler.

Urban load includes a lot of content, generally mainly refers to the service industry, manifested in the load of large commercial buildings, high-end office buildings, hotels and so on. Under normal circumstances, the load characteristics of large commercial buildings and high-end office buildings are mainly characterized by a large peak-to-valley difference in the load curve, the curve is relatively regular and the load is stable, and the annual change is not large. There is a close relationship between summer and winter temperature changes. For hotels, due to the uncertainty of hotel occupancy rate, the hotel's daily load curve is relatively uncertain, but there is a big difference between working days and holidays, peak tourist season and off-season.

Aiming at the above basic premise of urban micro-grid construction objectives and load characteristics, the present invention proposes a typical grid-connected scheme of micro-grid adapting to urban power grid:

Option 1A :

The construction site of this scheme is an industrial park or other places with demand, and the main goal of grid connection is to improve the reliability of load power supply. The micro-grid power supply is mainly based on power sources that can stably output power such as diesel generator systems or gas turbines, and supplies power for loads that require high power supply reliability. cost. The micro-grid adopts the AC system and merges into the original power grid system in the factory area.

In the AC microgrid based on the CERTS system, the load division is mainly based on the reliability requirements of power supply. For important loads with high power supply reliability requirements, they can be powered through the A feeder and supported by energy storage devices. General loads that require power supply reliability can be powered by feeder B, on which a certain amount of distributed power supply is installed. Other loads can be supplied by feeder C.

On this basis, the typical grid-connected scheme of Scheme 1A is shown in Figure 1, including the connection of the external power grid to the medium-voltage busbar through a transformer and the point of common connection (PCC). After that, the diesel generator system is directly connected to the same feeder A as the important load. Ensure timely supply of power to important loads when the external grid is powered off; the wind-solar-storage system is connected to the feeder A as an auxiliary. The general load is connected to another feeder B.

Option 1B :

The construction site of this scheme is located in an industrial park or a high-tech park. The main goal of grid connection is to improve energy utilization, use energy joint supply to solve the problem of cooling and heating in the park, and take into account the reliability of power supply. The micro-grid power supply adopts a gas turbine-based joint-supply synchronous unit, supplemented by small-capacity photovoltaic, wind power and energy storage devices, and can be integrated into the grid using an AC system or an AC-DC micro-grid system.

The main difference between Scheme 1B and Scheme 1A is that Scheme 1B adopts the method of heat-fixed electricity, which mainly ensures the heating and cooling supply in the factory area, and guarantees part of the electric load on the basis of ensuring the cooling and heating load. Therefore, the reliability of power supply of electric loads in this type of microgrid can only be taken into account, but cannot be guaranteed.

The AC system grid-connected scheme of Scheme 1B is shown in Figure 2. The joint-supply synchronous unit responsible for cooling and heating loads is connected to the same feeder A as the important loads; the power supply provided by photovoltaic power plants, or fans, or energy-based energy storage devices is used as an auxiliary power supply. , to supply power to other important loads and important office loads connected to the same feeder C; the power-off load is powered by feeder B, and in the grid-connected state, it is powered by the large power grid, and the load can be cut off when it is running off-grid.

In addition, Scheme 1B can directly choose the DC system to supply power for important DC loads (such as the central computer room), or choose the AC system to take care of other loads, which is quite different from Scheme 1A in terms of structure.

The grid-connected scheme of the AC and DC system of Scheme 1B is shown in Figure 3. The feeders A and B are basically the same as those in Figure 2. The difference is that the photovoltaic power station, or fan, or power-type energy storage device is connected to the DC bus. The important office loads that are also connected to the DC bus are powered; the power supply of the DC bus is processed by an inverter and a transformer and then connected to the feeder C, where the power-off load can be connected to the feeder C.

Option 1C :

The construction site of this grid-connected scheme is located on the roof of each building in the urban area or the surrounding open space. The grid-connected goal is to consume distributed power, small-scale application, and increase the added value of real estate. The type of micro-grid power supply mainly considers the use of single power sources such as photovoltaics and wind power, or the use of wind-solar-storage combined power generation, chemical fuel cells and other types of power sources. Use the original AC system of the house to connect to the grid.

The typical grid-connected scheme of Scheme 1C is shown in Figure 4. The photovoltaic power station, or fan, or power-type energy storage device is connected to the DC bus to supply power for important office loads that are also connected to the DC bus; the power supply of the DC bus is passed through the inverter After the transformer, it supplies power to AC loads such as municipal loads, shopping malls, supermarkets, etc., and can be further connected to feeder C through a transformer; general loads and power-off loads are respectively connected to feeders A and B.

To sum up, plan 1A aims to improve the reliability of power supply and is suitable for important loads that cannot be cut off. It has high requirements on power quality. Therefore, diesel generators are mainly used, and a small amount of wind and storage systems are added. Conditions permit. Choose gas turbines and biomass units and connect to the grid in the form of an AC system; if the load does not require high power quality, the diesel generator system can be replaced by a wind-solar-storage system. Option B aims to solve the demand for cooling and heating loads as the grid-connected goal, and takes into account the reliability of power supply. The cooling and heating loads must be satisfied, and the electrical loads must be balanced. The power supply selection is mainly based on gas turbines, and a small amount of wind and storage is added. Through AC systems and DC systems. The power grid is determined by heat, so there is no guarantee for the reliability of power supply. Plan 1C takes the consumption of distributed power as the goal of grid connection, and is suitable for ordinary residential and commercial loads. It chooses a single power source or wind and solar storage, fuel cells, etc. as the main power source, and connects to the grid in the form of an AC system.

However, in actual engineering, these basic schemes cannot cover all requirements. Generally, by combining them, an appropriate grid-connected combination scheme is selected.

An example shown in Figure 5 is a college microgrid project. The goal of grid connection is scientific and technological research, taking into account the maximum utilization of energy and improving the reliability of power supply for loads. Therefore, more types of microgrid power sources are applied: photovoltaic power generation Components, wind turbines, micro-combustion and diesel generators. This project makes full use of the roofs and open areas of the campus to install a certain capacity of photovoltaic power generation and wind power generation systems, and connects gas turbines, energy storage devices, electric vehicle charging stations, and power grids together with the large power grid. At the same time, build an intelligent power consumption system to realize two-way interaction of intelligent power consumption in the postgraduate dormitory building.

A typical structure of the AC microgrid is to set the main microgrid to 10kV switching station as the basis of the grid structure, and the bus tie switch between the busbars of the switching station is generally disconnected; the first-level microgrid can be controlled by the switch The ring network unit and power distribution station under it are composed of two busbars of the switch station to provide power respectively; the secondary microgrid can be composed of the user's internal power distribution room, which is composed of the switch station or ring network unit, and the power distribution station respectively powered by.

On this basis, in this example, substation-level microgrids, feeder-level microgrids, and single/multi-user level microgrids (corresponding to the main microgrid, primary microgrid, and secondary microgrid respectively) are formed as shown in Figure 5. . The substation-level microgrid has two switch stations, and each station has two busbars; the photovoltaic power station of the single/multi-user level microgrid can be connected to the first busbar of this level through the corresponding feeder, and the busbar of this level can be connected through the transformer. The bus bar of the corresponding switching station; the photovoltaic power station, wind turbine, energy storage system, diesel generator system, etc. of the single/multi-user level microgrid are connected to the same bus bar of this level, which can be connected to the bus bar of this level through a rectifier DC load power supply, and the same section of the bus is connected to a feeder of the feeder-level microgrid through a transformer; the busbar of the feeder-level microgrid can obtain power from the single/multi-user level microgrid and connect to the corresponding switch station through a transformer The feeder is then connected to the busbar of the switchyard, or the power supply of the photovoltaic power station connected to the feeder-level microgrid feeder can also be obtained, and directly connected to the busbar of the switchyard through the feeder of the corresponding switchyard; the photovoltaic power station of the feeder-level microgrid, Select to connect to the feeder of this level through a switch, or select to connect to the same section of busbar of the single/multi-user level microgrid; the gas turbine, internal combustion engine, energy storage battery, etc. of the feeder level microgrid, through the The level-one bus is connected with a switch to select a feeder connected to the corresponding switching station to connect to the bus of the switching station, or to select the same section of bus connected to the single/multi-user level microgrid.

This project is located in the urban area, and the surrounding power grid belongs to the urban power grid. The purpose of this project is to build a micro-grid system with complete functions. It mainly focuses on scientific research needs, and takes into account the maximum utilization of renewable energy from photovoltaics and wind turbines. Therefore, the basic plan is considered For scheme 1A and scheme 1C, the combination of the two schemes can not only meet the requirements of improving the reliability of power supply, but also meet the scientific research value brought by the comprehensive use of various micro-grid power sources, so that this project can meet the scientific research requirements of multiple loads and multiple power sources .

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (10)

1. the micro-grid connection system in urban distribution network, is characterized in that,

Described micro-grid connection system, to comprise with middle pressure bus through points of common connection connection transformer to access any one micro-capacitance sensor following or its combination in any of external electrical network:

System or gas turbine is sent out to provide the bavin of stable output power, for with described bavin send out system or gas turbine be linked into middle pressure bus after the AC load of wherein same feeder line power, and wind-light storage system access is to the auxiliary power supply source of this feeder line as described AC load;

To be responsible for carrying out cold and heat supply to cooling and heating load containing the synchronous unit of alliance type of gas turbine, and power for the AC load of the wherein same feeder line after being linked into middle pressure bus with the synchronous unit of this alliance type;

Power supply is that the DC load accessing same DC bus with described distributed power source is powered in a distributed manner; Power supply on described DC bus is that the AC load accessing same ac bus is powered by accessing an ac bus after inverter; The power supply of described ac bus is by being linked into one of them feeder line after middle pressure bus after another transformer.

2. the micro-grid connection system in urban distribution network as claimed in claim 1, is characterized in that,

Sending out system or gas turbine with bavin is the micro-capacitance sensor that the AC load of same feeder line is powered, and be arranged on industrial park, this micro-capacitance sensor adopts AC system to be incorporated to original network system.

3. the micro-grid connection system in urban distribution network as claimed in claim 1 or 2, is characterized in that,

With same feeder line apoplexy light-preserved system and the AC load that provides the bavin of stable output power to send out system or gas turbine to power, its power supply reliability requires the power supply reliability requirement higher than other loads being linked into another feeder line.

4. the micro-grid connection system in urban distribution network as claimed in claim 2, is characterized in that,

Send out in the micro-capacitance sensor of system or gas turbine containing the bavin stablizing output power, be provided with the grid-connected gas turbine of AC system or biomass unit; Or, in this micro-capacitance sensor, replace described bavin with wind-light storage system and send out system for described AC load and power.

5. the micro-grid connection system in urban distribution network as claimed in claim 1, is characterized in that,

To be responsible for cold and heat supply containing the synchronous unit of alliance type of gas turbine and to take into account the micro-capacitance sensor that the AC load for same feeder line powers, be arranged on industrial park or high-tech park; This micro-capacitance sensor adopts AC system when being incorporated to original network system, and any one or its combination in any in the photovoltaic plant at another feeder line place after middle pressure bus, blower fan, energy type energy storage device is that the AC load being linked into this another feeder line carries out auxiliary power supply; Another feeder line place after middle pressure bus has access to can power-off load.

6. the micro-grid connection system in urban distribution network as claimed in claim 1, is characterized in that,

To be responsible for cold and heat supply containing the synchronous unit of alliance type of gas turbine and to take into account the micro-capacitance sensor that the AC load for same feeder line powers, be arranged on industrial park or high-tech park; This micro-capacitance sensor adopts ac and dc systems when being incorporated to original network system, and any one or its combination in any in photovoltaic plant, blower fan, power-type energy storage device, for the DC load being linked into the same DC bus with its place carries out auxiliary power supply;

The power supply of DC bus by being linked into another feeder line after middle pressure bus after inverter connection transformer, and can be powered by power-off load for some being linked into this another feeder line; Another feeder line place after middle pressure bus has access to other can power-off load.

7. the micro-grid connection system in the urban distribution network as described in claim 5 or 6, is characterized in that,

Another feeder line place access after middle pressure bus can power-off load, its power supply reliability requires lower than the AC load at other feeder line places or the power supply reliability requirement of DC load.

8. the micro-grid connection system in urban distribution network as claimed in claim 1, is characterized in that,

Micro-capacitance sensor containing distributed power source is arranged on each building roof in city or periphery vacant lot, the distributed power source of this micro-capacitance sensor comprises: any one in single power supply, wind-solar-storage joint power generating source, chemical fuel cell power supply, and described single power supply is photo-voltaic power supply or wind-powered electricity generation power supply; This micro-capacitance sensor adopts AC system to be incorporated to original network system.

9. the micro-grid connection system in urban distribution network as claimed in claim 8, is characterized in that,

In photovoltaic plant, blower fan, power-type energy storage device any one or its combination, for the DC load being linked into the same DC bus with its place is powered; Another feeder line place after middle pressure bus has access to other AC load; Another feeder line place after middle pressure bus has access to can power-off load; The power supply reliability requirement of described DC load, higher than the power supply reliability requirement of other loads in this micro-grid connection system.

10. the micro-grid connection system in urban distribution network, is characterized in that, comprise successively: transformer station's rank micro-capacitance sensor, feeder line rank micro-capacitance sensor, list/multi-user's rank micro-capacitance sensor;

Wherein, described transformer station rank micro-capacitance sensor establishes two switchyards, and two section of first bus is established at each station, connects the first transformer be incorporated to external electrical network by corresponding points of common connection;

Some photovoltaic plants of described list/multi-user's rank micro-capacitance sensor, are linked into second bus of this grade by this grade of corresponding feeder line, and make second bus of this grade be linked into first bus at respective switch station by the second transformer;

Any one or its combination in any in system, other photovoltaic plants sent out by the described list/blower fan of multi-user's rank micro-capacitance sensor, energy-storage system, bavin, is linked into the same section of triple bus-bar of this grade and powers for the DC load being accessed this triple bus-bar by rectifier equally; Described triple bus-bar is also connected with the respective feed connection of feeder line rank micro-capacitance sensor by the 3rd transformer of described feeder line rank micro-capacitance sensor, and connects the 4th transformer to be linked into first bus at respective switch station by the 4th bus of feeder line rank micro-capacitance sensor;

The photovoltaic plant of described feeder line rank micro-capacitance sensor is by a diverter switch, select to be linked into this grade feeder line and and then be directly linked into first bus at respective switch station by the 5th bus of this grade, or select the triple bus-bar being linked into described list/multi-user's rank micro-capacitance sensor of described list/multi-user's rank micro-capacitance sensor;

Any one or its combination in any in the gas turbine of described feeder line rank micro-capacitance sensor, internal combustion engine, energy-storage battery is linked into the 6th bus of this grade, the power supply of the 6th bus is by another diverter switch, select to be linked into the first bus by the feeder line at respective switch station, or select the triple bus-bar being linked into described list/multi-user's rank micro-capacitance sensor.