CN206076972U - A kind of AC-DC hybrid power grid - Google Patents

Abstract

The utility model relates to the technical field of electric power equipment, in particular to an AC/DC hybrid power grid, which includes several substations, at least one of which is a flexible substation, and each substation includes a high-voltage AC system, a high-voltage DC system, and a low-voltage AC system , part or all of the low-voltage DC system, the high-voltage AC system, high-voltage DC system, low-voltage AC system, and low-voltage DC system in each flexible substation are interconnected into a network respectively. Further improvement has achieved the goal that the distribution network can provide high-voltage direct current and low-voltage direct current while providing high-voltage alternating current and low-voltage alternating current, and solves the problem that the existing distribution network can only provide single-mode alternating current and cannot directly provide direct current. Flexible interconnection between AC and DC systems of different voltage levels in the distribution network, flexible power flow adjustment and fast isolation of faults.

Description

An AC-DC hybrid power grid

technical field

The utility model relates to the technical field of electric power equipment, in particular to an AC/DC hybrid power grid.

Background technique

With the large-scale access of renewable energy to the distribution network, the large application of DC loads such as electric vehicles and data centers, there is a situation of coexistence of AC and DC power sources and AC and DC loads on the power distribution side. As an energy exchange node in the distribution network, the controllability and power supply flexibility of substations have gradually become the focus of attention and research in the industry. Traditional mechanical electromagnetic substations with a single power supply mode are difficult to meet the needs of future distribution network development.

In order to solve this problem, the patent document with the publication number CN203800620U discloses a distribution network system based on single-wire AC-DC hybrid technology. The system includes several AC sources and several DC sources. The first AC source and DC source are connected with The first Z-type transformer is connected, the first Z-type transformer is connected with the second Z-type transformer through a line, the second Z-type transformer is connected with the step-up wave current, the second Z-type transformer is also connected with the second AC source, the first AC The source is connected to a first load, and a second load is connected between the second AC source and the second Z-type transformer, so as to realize the integration of AC and DC without serious waveform distortion.

However, the comparison document mainly uses Z-type transformers with independent DC and AC sources, which has certain limitations for flexible networking, and is not applicable to situations where AC and DC power can still be provided without a separate DC source, so However, the AC/DC hybrid power supply network with flexible networking is still a major problem faced by those skilled in the art.

Utility model content

Therefore, the technical problem to be solved by this utility model is to overcome the defect that the distribution network in the prior art cannot provide large-scale DC power supply, so as to provide an AC-DC hybrid power grid. The specific solution is:

An AC-DC hybrid power grid, comprising

Several flexible substations, each flexible substation includes a plurality of voltage-level AC-DC interfaces, and each flexible substation includes part or all of the high-voltage AC system, the high-voltage DC system, the low-voltage AC system, and the low-voltage DC system, All flexible substations include at least one high-voltage AC system, one high-voltage DC system, one low-voltage AC system and one low-voltage DC system;

The high-voltage AC system, high-voltage DC system, low-voltage AC system, and low-voltage DC system in each flexible substation are interconnected to form a network respectively.

In the above-mentioned AC-DC hybrid power grid, the plurality of voltage-level AC-DC interfaces include a high-voltage AC interface, a high-voltage DC interface, a low-voltage AC interface, and a low-voltage DC interface.

In the above-mentioned AC-DC hybrid grid, wherein any two of the high-voltage AC system, the high-voltage DC system, the low-voltage AC system, and the low-voltage DC system realize bidirectional power flow through a flexible substation.

In the AC/DC hybrid grid described above, the voltage, frequency and phase of the high-voltage AC system and the low-voltage AC system of the flexible substation can be adjusted, and the voltages of the high-voltage DC system and the low-voltage DC system can be adjusted.

The above-mentioned AC-DC hybrid power grid, wherein a first voltage conversion module and a first voltage inverse conversion module are arranged between the high-voltage AC system and the low-voltage AC system, and the first voltage conversion module converts high-voltage AC power into low-voltage AC power, The first voltage inverse conversion module converts low-voltage alternating current into high-voltage alternating current.

The above-mentioned AC-DC hybrid power grid, wherein, the high-voltage direct current system and the low-voltage direct current system are provided with a second voltage conversion module and a second voltage inverse conversion module, and the second voltage conversion module converts high-voltage direct current into low-voltage direct current , the second voltage inverse conversion module converts low-voltage direct current into high-voltage direct current.

The above-mentioned AC-DC hybrid power grid, wherein a first power conversion module and a first power inverse conversion module are arranged between the high-voltage AC system and the high-voltage DC system, and the first power conversion module converts high-voltage alternating current into high-voltage direct current, the first power inverse conversion module converts high-voltage direct current into high-voltage alternating current.

The above-mentioned AC-DC hybrid power grid, wherein, a second power conversion module and a second power inverse conversion module are arranged between the low-voltage AC system and the low-voltage DC system, and the second power conversion module converts low-voltage AC power into low-voltage direct current, and the second power inverse conversion module converts low-voltage direct current into low-voltage alternating current.

The above-mentioned AC/DC hybrid power grid, wherein, the first voltage conversion module and the first voltage inverse conversion module are independent modules or an integrated module integrated together, and the second voltage conversion module and the second voltage inverse conversion module The module is an independent module or an integrated module integrated together. The first power conversion module and the first power inverse conversion module are independent modules or an integrated integrated module. The second power conversion module It is an independent module or an integrated module integrated with the second power inverse conversion module.

In the aforementioned AC/DC hybrid power grid, the high-voltage DC system is directly connected to new energy sources and energy storage systems for providing electric energy when the upper-level power grid fails or is abnormal.

The above-mentioned AC-DC hybrid power grid, wherein the low-voltage AC system and the low-voltage DC system are respectively connected with distributed power sources and energy storage to provide electric energy when the upper-level power grid fails or is abnormal.

The above-mentioned AC/DC hybrid grid, wherein, in the AC/DC hybrid grid, when one or several flexible substations fail, other flexible substations in the AC/DC hybrid grid except for the faulty flexible substation work normally.

The technical scheme of the utility model has the following advantages:

The AC-DC hybrid power grid provided by the utility model further improves the function of the distribution network in the present technology to provide high-voltage alternating current and low-voltage direct current, and can provide high-voltage direct current and low-voltage direct current while providing high-voltage alternating current and low-voltage alternating current. The purpose of direct current is to solve the problem that the existing distribution network provides a single mode of alternating current and cannot directly provide direct current.

In the AC-DC hybrid power grid provided by the utility model, high-voltage AC power, high-voltage DC power, low-voltage AC power and low-voltage DC power can be mutually converted. At the same time, the high-voltage DC system in the AC-DC hybrid grid of the utility model is directly connected to The distributed power supply can be directly supplied to the high-voltage DC system and the low-voltage DC system, and the distributed power supply and the energy storage system can be respectively connected to the low-voltage AC system and the low-voltage DC system, and can be connected to each other in the flexible substation. It can also provide power for the AC-DC hybrid grid when the upper-level grid fails or is abnormal.

Description of drawings

In order to more clearly illustrate the specific implementation of the utility model or the technical solutions in the prior art, the accompanying drawings that need to be used in the description of the specific implementation or the prior art will be briefly introduced below. Obviously, the following descriptions The accompanying drawings are some implementations of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without any creative work.

Fig. 1 is a schematic structural diagram of an AC/DC hybrid grid in a preferred embodiment of the present invention;

2a-2c are schematic structural diagrams of flexible substations in an AC/DC hybrid power grid in a preferred embodiment of the present invention;

Reference signs:

1-The first flexible substation 2-The second flexible substation 3-The third flexible substation

11.21.31 - High voltage AC systems 12.22.32 - High voltage DC systems

13.23.33 - Low voltage AC systems 14.24.34 - High voltage DC systems.

detailed description

The technical solutions of the utility model will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are part of the embodiments of the utility model, but not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

In the description of the present utility model, it should be noted that the terms "first", "second", and "third" are used for description purposes only, and should not be understood as indicating or implying relative importance.

In the description of the present utility model, it should be noted that, unless otherwise clearly stipulated and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection, or Integral connection; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary, or it can be the internal communication of two components, it can be wireless connection or wired connection. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present utility model in specific situations.

Example 1

Referring to the structure shown in Figure 1, the utility model provides an AC-DC hybrid grid, including several flexible substations, as a preferred embodiment, the AC-DC hybrid grid includes 3 flexible substations, the first flexible substation 1 , the second flexible substation 2 and the third flexible substation 3, each flexible substation includes one or more of the high-voltage AC system, the high-voltage direct current system, the low-voltage alternating current system and the low-voltage direct current system, composed of the first flexible substation 1, the second flexible substation The AC-DC hybrid power grid formed by the flexible substation 2 and the third flexible substation 3 includes at least one high-voltage AC system, one high-voltage DC system, one low-voltage AC system and one low-voltage DC system. Each flexible substation includes interfaces of multiple voltage levels. As a preferred embodiment of the present invention, each flexible substation includes multiple levels of voltage interfaces, which can be but not limited to high-voltage AC interfaces, high-voltage DC interfaces, and low-voltage AC interfaces. and low-voltage DC interface, the first flexible substation 1 includes a high-voltage AC system 11, a high-voltage DC system 12, a low-voltage AC system 13, and a low-voltage DC system 14, and the second flexible substation 2 includes a high-voltage AC system 21, a high-voltage DC system 22, and a low-voltage AC system 23 and the low-voltage direct current system 24, the third flexible substation 3 includes a high-voltage alternating current system 31, a high-voltage direct current system 32, a low-voltage direct current system 33 and a low-voltage direct current system 34, wherein, the high-voltage alternating current interface 110 of the first flexible substation 1 is connected to the second flexible The high-voltage AC interface 210 of the substation 2 and the high-voltage AC interface 310 of the third flexible substation 3 are interconnected to form a high-voltage AC network; the high-voltage DC interface 120 of the first flexible substation 1 and the high-voltage DC interface 220 of the second flexible substation 2 and the third flexible substation The high-voltage DC interface 320 of the substation 3 is interconnected to form a high-voltage DC network, and the new energy and energy storage system can be directly connected to the high-voltage DC network; the low-voltage AC interface 130 of the first flexible substation 1 and the low-voltage AC interface of the second flexible substation 2 230 and the low-voltage AC interface 330 of the third flexible substation 3 are interconnected to form a low-voltage AC network; the low-voltage DC interface 140 of the first flexible substation 1 and the low-voltage DC interface 240 of the second flexible substation 2 and the low-voltage DC interface of the third flexible substation 3 340 interconnected to form a low-voltage DC network.

In Fig. 1, the grid access terminal 100 of the first flexible substation 1, the grid access terminal 200 of the second flexible substation 2 and the grid access terminal 300 of the third flexible substation 3 are respectively the first flexible substation 1 and the second flexible substation Substation 2 and the third flexible substation 3 provide interfaces for grid access. It is worth noting that the upper-level grid connected to the grid access terminal 100, grid access terminal 200, and grid access terminal 300 may or may not be completely the same , even the first flexible substation 1, the second flexible substation 2 and the third flexible substation 3 are connected to different upper-level power grids, and the low-voltage AC in the first flexible substation 1, the second flexible substation 2 and the third flexible substation 3 The system and the low-voltage DC system are respectively connected to distributed power sources or energy storage equipment to provide power when the upper-level power grid connected to the flexible substation fails or is abnormal.

Under normal circumstances, the first flexible substation 1, the second flexible substation 2 and the third flexible substation 3 can all receive the electric energy in the upper-level power grid, and then provide it to the corresponding load through a series of transformations, and when the upper-level power grid cannot When one or more flexible substations in the AC-DC hybrid power grid cannot receive the power provided by the superior power grid due to power supply or transmission line failure, the first flexible substation 1 and/or the second flexible substation 2 and/or the first flexible substation 2 The distributed power supply or energy storage equipment connected to the low-voltage AC system and low-voltage DC system in the three flexible substations 3 can provide electric energy for the first flexible substation 1 and/or the second flexible substation 2 and/or the third flexible substation 3, avoiding once The technical defect that the power grid will not work if it cannot receive the electric energy provided by the superior power grid.

Preferably, in the AC/DC hybrid power grid in this embodiment, when one or more flexible substations fail, other flexible substations in the AC/DC hybrid grid except for the failed flexible substation work normally.

In the AC/DC hybrid power grid of this embodiment, when a flexible substation fails and cannot work normally, preferably but not limited to, the first flexible substation 1 cannot work normally for some reason, then the second flexible substation 2 and the third flexible substation The AC-DC hybrid grid composed of 3 works as usual, and when the first flexible substation 1 and the second flexible substation 2 fail to work, the third flexible substation works normally to provide loads in the AC-DC hybrid grid. electrical energy.

The reason why the utility model can provide direct current, including high-voltage direct current and low-voltage direct current, is that the flexible substation in the utility model is provided with a power conversion module, including a first power conversion module and a second power conversion module, the first power conversion module Convert high-voltage alternating current to high-voltage direct current, and the second power conversion module converts low-voltage alternating current to low-voltage direct current. At the same time, the utility model is provided with a second voltage conversion module and a second voltage inverse conversion module, which can be used between low-voltage direct current and high-voltage direct current. Mutual transformation completely breaks the technical solution that traditional substations can only provide alternating current (including high-voltage alternating current and low-voltage alternating current). Among them, the flexible substation is a substation based on power electronics, which can also provide direct current while providing alternating current.

Specifically, referring to the structures shown in Figures 2a-2c, in Figure 2a, the first flexible substation 1 includes a first voltage conversion module 19 and a first voltage inverse conversion module 10, the first voltage conversion module 19 and the first voltage inverse conversion module 10 are respectively connected to the high-voltage AC system 11 and the low-voltage AC system 13, the first voltage conversion module 19 transforms part of the high-voltage AC power in the high-voltage AC system 11 into low-voltage AC power and connects it to the low-voltage AC system 13, and the first voltage inverse conversion module 10 is to transform the low-voltage alternating current in the low-voltage alternating current system 13 into high-voltage alternating current and connect it to the high-voltage alternating current system 11; the first flexible substation 1 also includes a second voltage transformation module 124 and a second voltage inverse transformation module 142, the second voltage transformation The module 124 and the second voltage inverse change module 142 are respectively connected to the high-voltage direct current system 12 and the low-voltage direct current system 14, and the second voltage change module 124 converts part of the high-voltage direct current in the high-voltage direct current system 12 into low-voltage direct current and stores it in the low-voltage direct current system 14, the second voltage inverse change module 142 converts part of the low-voltage direct current in the low-voltage direct current system 14 into high-voltage direct current and connects it to the high-voltage direct current system 12; the first flexible substation 1 also includes a first power conversion module 15 and a second power The conversion module 16, wherein the first power conversion module 15 is respectively connected to the high-voltage AC system 11 and the high-voltage DC system 12, and converts part of the high-voltage AC power in the high-voltage AC system 11 into high-voltage direct current in the high-voltage DC system, and the second power conversion module 16 is respectively connected to the low-voltage AC system 13 and the low-voltage DC system 14, and converts part of the low-voltage AC power in the low-voltage AC system 13 into the low-voltage DC power of 14 in the low-voltage DC system; the first flexible substation 1 also includes a first power inverse conversion module 17 and The second power inverse conversion module 18, wherein the first power inverse conversion module 17 is connected to the high-voltage AC system 11 and the high-voltage DC system 12 respectively, converts part of the high-voltage direct current in the high-voltage direct current system 13 into high-voltage alternating current and connects it to the high-voltage alternating current system In 11, the second power inverse conversion module 18 is respectively connected to the low-voltage AC system 13 and the low-voltage DC system 14, and converts part of the low-voltage direct current in the low-voltage direct current system 14 into low-voltage alternating current and connects it to the low-voltage alternating current system 13.

Similar to this, referring to the structure shown in Figure 2b, the second flexible substation 2 includes a first voltage conversion module 29 and a first voltage inverse conversion module 20, and the first voltage conversion module 29 and the first voltage inverse conversion module 20 are respectively connected to the high voltage The AC system 21 is connected to the low-voltage AC system 23 to complete the transformation of high-voltage alternating current and low-voltage alternating current. The principle of voltage transformation is the same as that of the first voltage transformation module 19 and the first voltage inverse transformation module 10 in FIG. 2a. Here, Not to repeat; the second flexible substation 2 also includes a second voltage conversion module 224 and a second voltage inverse conversion module 242, the second voltage conversion module 224 and the second voltage inverse conversion module 242 are respectively connected with the high-voltage direct current system 22 and the low-voltage DC system 22 The DC system 24 is connected to complete the mutual conversion of high-voltage DC and low-voltage DC; the second flexible substation 2 also includes a first power conversion module 25 and a second power conversion module 26, and the first power conversion module 25 is connected to the high-voltage AC system 21 and The high-voltage direct current system 22 is connected to transform part of the high-voltage alternating current in the high-voltage alternating current system into high-voltage direct current in the high-voltage direct current system. Part of the low-voltage alternating current in 23 is converted into low-voltage direct current in the low-voltage direct current system 24; the second flexible substation 2 also includes a first power inverse conversion module 27 and a second power inverse conversion module 28, and the first power inverse conversion module 27 and The high-voltage AC system 21 is connected to the high-voltage DC system 22 to complete the conversion of part of the high-voltage direct current in the high-voltage direct current system to high-voltage alternating current. Part of the low voltage direct current in the direct current system 24 is transformed into low voltage alternating current.

Referring to the structure shown in Figure 2c, the third flexible substation 3 includes a first voltage conversion module 39, a first voltage inverse conversion module 30, a second voltage conversion module 324 and a second voltage inverse conversion module 342, the first voltage conversion module 39 1. The connection mode and working principle of the first voltage inverse conversion module 30, the second voltage conversion module 324 and the second voltage inverse conversion module 342 are similar to those of the first flexible substation 1 and the second flexible substation 2; the third flexible substation 3 It also includes a first power conversion module 35, a second power conversion module 36, a first power inverse conversion module 37 and a second power inverse conversion module 38, wherein the first power conversion module 35 and the second power conversion module in the third flexible substation 3 Connection relationship between the power conversion module 36, the first power inverse conversion module 37 and the second power inverse conversion module 38, and the high-voltage AC system 31, the high-voltage DC system 32, the low-voltage AC system 33, and the low-voltage DC system 34 in the third flexible substation 3 The connection relationship between the high-voltage AC system, the high-voltage DC system, the low-voltage AC system and the low-voltage DC system in the first flexible substation 1 and the second flexible substation 2 is similar, and the working principles and functions are also similar, and will not be repeated here.

Wherein, the first voltage conversion module and the first voltage inverse conversion module of each flexible substation can be independent modules, or an integrated module integrated together; the second voltage conversion module and the second voltage inverse conversion module can be An independent module, or an integrated module integrated together; the first power conversion module and the first power inverse conversion module may be independent modules, or an integrated integrated module; the second power conversion module and The second power inverse conversion module can be an independent module, or an integrated module integrated together. Taking the first flexible substation 1 as an example to illustrate: the first voltage conversion module 19 and the first voltage inverse conversion module 10 can be An independent module, or an integrated module integrated together; the second voltage conversion module 124 and the second voltage inverse conversion module 142 may be independent modules, or an integrated integrated module; the first power conversion module 15 and the first power inverse conversion module 17 can be independently designed modules, and can also be an integrated module integrated together; similarly, the second power conversion module 16 and the second power inverse conversion module 18 can be independently designed modules , can also be an integrated module integrated together. For the voltage conversion module, voltage inverse conversion module, power conversion module and power inverse conversion module in the second flexible substation 2 and the third flexible substation 3, the same design is done.

The flexible substation in the utility model (including the first flexible substation 1, the second flexible substation 2 and the third flexible substation 3) can adjust the voltage, power and phase of the high-voltage AC system or the low-voltage AC system through control. The control regulates the voltage of the HVDC system or the LVDC system.

At the same time, the low-voltage AC system and the low-voltage DC system in the flexible substation in the utility model include distributed power sources, including wind power generation and solar power generation, etc., and the low-voltage AC system and/or low-voltage DC system directly obtain the distributed power source connected to it. The electric energy generated by the power supply is used for direct use or back-up mutual conversion.

Preferably, the high-voltage DC system in this embodiment is directly connected to new energy and energy storage systems, especially when the upper-level grid is disconnected or other faults cause the flexible substation to fail to obtain electrical energy from the upper-level grid and fail to work, directly provide electrical energy to Avoid the technical defect that the AC-DC hybrid grid will not work once the upper-level grid fails.

At the same time, the low-voltage AC system and the low-voltage DC system in the flexible substation are respectively connected to distributed power sources and energy storage to provide electric energy when the upper-level power grid fails.

At the same time, the flexible substations in the AC-DC hybrid grid in this embodiment can operate independently, or can be connected to form a hybrid grid. The advantage of independent operation is that one or several flexible substations in the AC-DC hybrid grid When a fault occurs, the flexible substations in the AC-DC hybrid grid except for the faulty flexible substation can still work normally and provide electric energy, which greatly expands the flexibility of the AC-DC hybrid grid and reduces the failure rate. .

The flexible substation in the utility model also includes power conversion modules for converting DC voltage into AC voltage, which are respectively the first power inverse conversion module and the second power inverse conversion module. This design makes the flexible substation in the AC-DC hybrid power grid The electric energy in any two systems in the high-voltage AC system, high-voltage DC system, low-voltage AC system, and low-voltage DC system can flow in both directions and be transformed into each other.

To sum up, the AC-DC hybrid power grid constructed by the utility model can output high-voltage direct current while outputting high-voltage alternating current and low-voltage alternating current by setting the first power conversion module and the second power conversion module in the flexible substation. and low-voltage DC, at the same time, the first power inverse conversion module, the second power inverse conversion module, the first voltage inverse conversion module and the second voltage inverse conversion module are set in the flexible substation, so that the AC-DC hybrid of the present utility model In the flexible substation in the power grid, the high-voltage AC, high-voltage DC, low-voltage AC and low-voltage DC are mutually converted, effectively solving the technical problem that the existing distribution network can only provide AC voltage and a single power supply mode, and improving the flexibility of the distribution network and controllability.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the scope of protection of the utility model.

Claims (12)

1. a kind of AC-DC hybrid power grid, it is characterised in that include

Several flexible transformer stations, described each flexible transformer station include multiple electric pressure NETOMACs, it is described each Flexible transformer station includes the part in high-voltage alternating system, high-voltage direct current, low-voltage alternating-current system, low-voltage direct-current system respectively Or all, in flexible transformer station of institute, at least include high-voltage alternating system, high-voltage direct current, a low-voltage alternating-current System and a low-voltage direct-current system；

High-voltage alternating system, high-voltage direct current in described each flexible transformer station, low-voltage alternating-current system, low-voltage direct-current system Net is unified into respectively mutually.

2. AC-DC hybrid power grid according to claim 1, it is characterised in that the plurality of electric pressure NETOMAC bag Include high-voltage alternating interface, HVDC interface, low-voltage alternating-current interface and low-voltage direct interface.

3. AC-DC hybrid power grid according to claim 1, it is characterised in that the high-voltage alternating system, HVDC system Unite, to and fro flow of power is realized by flexible transformer station between low-voltage alternating-current system, low-voltage direct-current system any two.

4. AC-DC hybrid power grid according to claim 1, it is characterised in that the high-voltage alternating system of the flexible transformer station And the voltage of the voltage, frequency and the equal scalable of phase place, the high-voltage direct current and low-voltage direct-current system of low-voltage alternating-current system Scalable.

5. AC-DC hybrid power grid according to claim 3, it is characterised in that the high-voltage alternating system and low-voltage alternating-current system First voltage conversion module and first voltage inverse transform module are provided between system, high pressure is handed over by the first voltage conversion module Stream electricity is transformed to low-voltage AC, and low-voltage AC is transformed to High Level AC Voltage by the first voltage inverse transform module.

6. AC-DC hybrid power grid according to claim 5, it is characterised in that the high-voltage direct current and the low-pressure direct It is provided with second voltage conversion module and second voltage inverse transform module in streaming system, the second voltage conversion module is by high pressure DC power conversion is low-voltage DC, and low-voltage DC is transformed to high voltage direct current by the second voltage inverse transform module.

7. AC-DC hybrid power grid according to claim 6, it is characterised in that the high-voltage alternating system and the high straightening The first power conversion modules and the first power inverting mold changing block are provided between streaming system, first power conversion modules are by height Pressure convert alternating current is high voltage direct current, and high voltage direct current is transformed to High Level AC Voltage by the first power inverting mold changing block.

8. AC-DC hybrid power grid according to claim 7, it is characterised in that the low-voltage alternating-current system and the low-pressure direct The second power conversion modules and the second power inverting mold changing block are provided between streaming system, second power conversion modules will be low Pressure convert alternating current is low-voltage DC, and low-voltage DC is transformed to low-voltage AC by the second power inverting mold changing block.

9. AC-DC hybrid power grid according to claim 8, it is characterised in that the first voltage conversion module with it is described First voltage inverse transform module is independent module or the integrated module to integrate, the second voltage conversion module It is independent module or integrated module to integrate with the second voltage inverse transform module, first power becomes It is independent module or the integrated module to integrate that mold changing block and first power inverting change the mold block, described second It is independent module or the integrated module to integrate that power conversion modules and second power inverting change the mold block.

10. AC-DC hybrid power grid according to claim 1, it is characterised in that the high-voltage direct current is directly accessed newly The energy and energy-storage system, for when higher level's electric network fault or it is abnormal when electric energy is provided.

11. AC-DC hybrid power grids according to claim 1, it is characterised in that the low-voltage alternating-current system, low-voltage direct system System is respectively connected to distributed power source or energy storage device, for when higher level's electric network fault or it is abnormal when electric energy is provided.

12. AC-DC hybrid power grids according to claim 1, it is characterised in that in the AC-DC hybrid power grid, one or Flexible change when the several flexible transformer stations of person break down, in AC-DC hybrid power grid in addition to the flexible transformer station broken down Power station normal work.