CN112491098A

CN112491098A - Multi-port intelligent micro-grid energy exchanger and control method and system thereof

Info

Publication number: CN112491098A
Application number: CN201910865216.7A
Authority: CN
Inventors: 丁保迪; 季宇; 苏剑; 刘海涛; 吴鸣; 熊雄; 张颖; 胡转娣; 管荑; 程艳
Original assignee: State Grid Corp of China SGCC; China Electric Power Research Institute Co Ltd CEPRI; Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd; State Grid Shandong Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; China Electric Power Research Institute Co Ltd CEPRI; Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd; State Grid Shandong Electric Power Co Ltd
Priority date: 2019-09-12
Filing date: 2019-09-12
Publication date: 2021-03-12

Abstract

The invention discloses a multi-port intelligent micro-grid energy exchanger and a control method and a system thereof, wherein the energy exchanger comprises: the system comprises a photovoltaic chopper, at least two energy storage choppers, an output chopper, a master inverter, a slave inverter and a control chip; one end of the photovoltaic chopper is connected with one end of the master inverter, one end of one energy storage chopper is connected with one end of the slave inverter, and one end of the other energy storage chopper is connected with one end of the output chopper; the other end of the master inverter and the other end of the slave inverter are connected to generate three paths of alternating current ports and a first path of direct current port, and the other end of the output chopper generates a second path of direct current port; the other end of the photovoltaic chopper is externally connected with a photovoltaic power station, and the other ends of the two energy storage choppers are respectively connected with an external energy storage. The invention realizes new energy grid connection, reduces the system occupation area, reduces the investment cost and is convenient for the construction work of the energy Internet.

Description

Multi-port intelligent micro-grid energy exchanger and control method and system thereof

Technical Field

The invention relates to the field of micro-grids and energy exchange, in particular to a multi-port intelligent micro-grid energy exchanger and a control method and a control system thereof.

Background

The energy internet comprehensively utilizes advanced power electronic technology, information technology and intelligent management technology, and a large number of energy nodes such as a novel power network, an oil network, a natural gas network and the like which are composed of distributed energy acquisition devices, distributed energy storage devices and various loads are interconnected to realize energy peer-to-peer exchange and sharing network of energy bidirectional flow. The energy internet is rapidly developed in recent years, different researchers develop and realize the energy internet from different angles respectively, and the new generation intelligent network which takes electric power as a core, and is deeply integrated and interactive with energy and information is established. The micro-grid is a basic composition unit of a regional energy Internet, the traditional micro-grid construction scheme is based on special power electronic grid-connected interfaces such as a photovoltaic converter, an energy storage converter and a fan converter to realize new energy grid connection, the system is wide in occupied area, large in investment and not beneficial to construction work of the energy Internet.

Disclosure of Invention

In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a multi-port smart microgrid energy switch, comprising: the system comprises a photovoltaic chopper, at least two energy storage choppers, an output chopper, a master inverter, a slave inverter and a control chip;

one end of the photovoltaic chopper is connected with one end of the master inverter, one end of one energy storage chopper is connected with one end of the slave inverter, and one end of the other energy storage chopper is connected with one end of the output chopper;

the other end of the master inverter and the other end of the slave inverter are connected to generate three paths of alternating current ports and a first path of direct current port, the other end of the output chopper generates a second path of direct current port, the first path of alternating current port is connected with a power grid, and the rest alternating current ports and the first path of direct current port and the second path of direct current port are connected with a load;

the other end of the photovoltaic chopper is externally connected with a photovoltaic power station, and the other ends of the two energy storage choppers are respectively connected with an external energy storage.

Preferably, the first path of dc port is connected to a 48V dc load.

Preferably, the second dc port is connected to a 400V dc load.

Preferably, the first ac port is connected to the grid sequentially through the inverter-side grid-connected switch and the grid-side grid-connected switch.

Based on the same inventive concept, the invention also provides a control method for the multi-port intelligent micro-grid energy exchanger, which comprises the following steps:

s1, respectively detecting the stored energy voltage connected with each energy storage chopper through each energy storage chopper, and when the stored energy voltage of any path is greater than the energy storage threshold, starting the energy storage chopper corresponding to the stored energy voltage greater than the energy storage threshold to operate in a constant direct current bus voltage mode and executing S2; otherwise, detecting whether the photovoltaic power station is electrified or not through the photovoltaic chopper, charging any path of stored energy when the photovoltaic power station is electrified, and continuously detecting the voltage of the stored energy;

s2, setting an operation mode of an output chopper and judging whether the voltage on the grid side is electrified, starting an operation grid-connected mode when the voltage on the grid side is electrified, executing S3 to send the photovoltaic power to the grid side in a maximum output mode, otherwise, starting an off-grid mode, and executing S4 to send the photovoltaic power to a load side in the maximum output mode;

s3, setting a grid-connected operation mode of the master inverter and the slave inverter, and determining whether the photovoltaic power station charges each energy storage based on the charge state of each energy storage;

s4, setting off-grid operation modes of the master inverter and the slave inverter, and determining the operation mode of the photovoltaic chopper and the operation state of each stored energy based on the relation between the photovoltaic power and the load power and the charge state of each stored energy.

Preferably, the operation of the energy storage chopper corresponding to the energy storage voltage > the energy storage threshold in the fixed dc bus voltage mode is started and performed S2, including:

and when the energy storage voltage is larger than the energy storage threshold value, the energy storage chopper corresponding to the energy storage threshold value is started to operate in a fixed direct current bus voltage mode, whether the voltage on the direct current bus side reaches a control target value is judged, if the direct current bus voltage is larger than the control target value, a grid-connected switch on the inverter side is closed to execute S2, and otherwise, the voltage of each energy storage is continuously detected.

Preferably, the setting of the operation mode of the output chopper includes:

setting a low-voltage value of the operation of the output chopper, and taking the output chopper as a charging pile;

the low voltage is 400V.

Preferably, the starting of the grid-connected operation mode when the grid-side voltage is charged and the performing of S3 sending the photovoltaic power to the grid side in the maximum output mode, or else, the starting of the off-grid operation mode and the performing of S4 sending the photovoltaic power to the load side in the maximum output mode includes:

and when the grid side voltage is electrified, closing the grid side grid-connected switch and starting the operation grid-connected mode, executing S3 to send the photovoltaic power to the grid side in the maximum output mode, otherwise, disconnecting the grid side grid-connected switch and starting the off-grid mode, and executing S4 to send the photovoltaic power to the load side in the maximum output mode.

Preferably, the setting of the grid-connected operation mode of the master inverter and the slave inverter includes:

and setting the master inverter to operate in a PQ mode with given grid-connected power, and automatically following the master inverter by the slave inverter.

Preferably, the determining whether the photovoltaic power plant charges each energy storage based on each energy storage state of charge includes:

when the state of charge of the stored energy which is put into operation in a fixed direct current bus mode is lower than 90%, changing a given value of grid-connected power, and charging the corresponding stored energy by the photovoltaic power station until the stored energy is charged to 90%, or else, fully connecting the photovoltaic power to the grid;

when the charge state of the energy storage which is not put into the operation of the fixed direct current bus mode is lower than 90%, the power distribution coefficient is changed according to the proportion of the charge state of each energy storage, the photovoltaic power station is enabled to charge each energy storage, when the charge state of each energy storage is 90%, the charging is stopped, and the photovoltaic power is completely connected to the grid.

Preferably, before the off-grid mode is started, the method includes:

and judging the charge state of each stored energy, starting an off-grid mode when the charge state of any stored energy is more than 30%, and otherwise, continuously detecting the voltage of each stored energy.

Preferably, the setting of the off-grid operation mode of the master inverter and the slave inverter includes:

the master inverter is set to run in a VF mode under the condition of 380V alternating voltage, and the slave inverter automatically follows the master inverter.

Preferably, the determining the operation mode of the photovoltaic chopper and the operation state of each stored energy based on the relationship between the photovoltaic power and the load power and the state of charge of each stored energy includes:

when the photovoltaic power is greater than the load power, the residual photovoltaic power in the photovoltaic chopper charges the energy storage with the charge state of less than 90%, when the charge state of the energy storage reaches 90%, the residual photovoltaic power can raise the voltage of a direct current bus, the photovoltaic chopper enters a power limiting operation mode, and the given value of the power limiting is equal to the load power;

when the photovoltaic power is less than the load power and the charge state of each energy storage is more than 30%, the photovoltaic chopper operates at the maximum power, each energy storage enters a fixed direct current bus mode, and each energy storage discharges to the load according to droop control;

when the photovoltaic power is lower than the load power and the charge state of any stored energy is lower than 30%, the stored energy with the charge state lower than 30% is standby;

when the photovoltaic power is < load power and the state of charge of each stored energy is below 30%, each stored energy is in standby to return to S1.

Preferably, the setting of the grid-connected operation mode of the master inverter and the slave inverter further includes:

the multi-port intelligent micro-grid energy exchanger carries out island detection in grid-connected operation control, and if an island occurs, the multi-port intelligent micro-grid energy exchanger is switched to a VF mode according to over-voltage and under-voltage or over-frequency and under-frequency.

Preferably, the setting of the off-grid operation mode of the master inverter and the slave inverter further includes:

and if the power grid is recovered to be normal in the off-grid operation mode, the multi-port intelligent micro-grid energy exchanger is switched to a grid-connected operation mode.

Based on the same invention concept, the invention also provides a control system for the multi-port intelligent micro-grid energy exchanger, which comprises the following steps:

the voltage detection module is used for respectively detecting the voltage of the stored energy connected with each energy storage chopper through each energy storage chopper, and when the voltage of any path of stored energy is greater than the energy storage threshold, the energy storage chopper corresponding to the energy storage voltage greater than the energy storage threshold starts a fixed direct-current bus voltage mode to operate and executes the judgment module; otherwise, detecting whether the photovoltaic power station is electrified or not through the photovoltaic chopper, charging any path of stored energy when the photovoltaic power station is electrified, and continuously detecting the voltage of the stored energy;

the judging module is used for setting the operation mode of the output chopper and judging whether the voltage on the grid side is electrified or not, when the voltage on the grid side is electrified, the operation grid-connected mode is started, the grid-connected module is called to send the photovoltaic power to the grid side in the maximum output mode, otherwise, the off-grid mode is started, and the off-grid module is called to send the photovoltaic power to the load side in the maximum output mode;

the grid-connected module is used for setting a grid-connected operation mode of the master inverter and the slave inverter and determining whether the photovoltaic power station charges each energy storage based on the charge state of each energy storage;

and the off-grid module is used for setting off-grid operation modes of the master inverter and the slave inverter, and determining the operation mode of the photovoltaic chopper and the operation state of each stored energy based on the relation between the photovoltaic power and the load power and the charge state of each stored energy.

Preferably, the judging module includes:

a grid connection judging unit for closing the grid side grid connection switch and starting the operation grid connection mode when the grid side voltage is electrified, executing the grid connection module to send the photovoltaic power to the grid side in the maximum output mode,

and the off-grid judging unit is used for disconnecting the grid-side grid-connected switch to start an off-grid mode when the grid-side voltage is not electrified, and executing the off-grid module to send the photovoltaic power to the load side in a maximum output mode.

Preferably, the grid-connected module includes:

the first grid connection unit is used for changing a given grid connection power value when the charge state of the stored energy which is put into a certain direct current bus mode for operation is lower than 90%, the photovoltaic power station charges the corresponding stored energy until the stored energy is charged to 90%, and otherwise, the photovoltaic power is completely connected to the grid;

and the second grid-connected unit is used for changing the power distribution coefficient according to the proportion of the charge state of each energy storage when the charge state of the energy storage which is not put into the operation in the fixed direct current bus mode is lower than 90%, so that the photovoltaic power station charges each energy storage, and stops charging when the charge state of each energy storage is 90%, and the photovoltaic power is completely connected to the grid.

Preferably, the off-grid module includes:

the first off-grid unit is used for charging the energy storage with the charge state of < 90% by the residual photovoltaic power in the photovoltaic chopper when the photovoltaic power is greater than the load power, and enabling the photovoltaic chopper to enter a power limiting operation mode when the voltage of a direct current bus is raised by the residual photovoltaic power after the charge state of the energy storage reaches 90%, wherein the given value of the power limiting is the load power;

the second off-grid unit is used for operating the photovoltaic chopper at the maximum power when the photovoltaic power is less than the load power and the charge state of each stored energy is more than 30%, and each stored energy is discharged to the load according to droop control;

the third off-grid unit is used for storing energy with the charge state lower than 30% for standby when the photovoltaic power is lower than the load power and the charge state of any stored energy is lower than 30%;

and the fourth off-grid unit is used for calling the detection voltage module in a standby mode when the photovoltaic power is smaller than the load power and the charge state of each energy storage is lower than 30%.

Preferably, the control system is disposed on a control chip, and the control chip is connected to the photovoltaic chopper, each energy storage chopper, the output chopper, the master inverter and the slave inverter respectively.

Compared with the prior art, the invention has the beneficial effects that:

(1) the energy exchanger provided by the invention comprises: the system comprises a photovoltaic chopper, at least two energy storage choppers, an output chopper, a master inverter, a slave inverter and a control chip; one end of the photovoltaic chopper is connected with one end of the master inverter, one end of one energy storage chopper is connected with one end of the slave inverter, and one end of the other energy storage chopper is connected with one end of the output chopper; the other end of the master inverter and the other end of the slave inverter are connected to generate three paths of alternating current ports and a first path of direct current port, the other end of the output chopper generates a second path of direct current port, the first path of alternating current port is connected with a power grid, and the rest alternating current ports and the first path of direct current port and the second path of direct current port are connected with a load; the other ends of the photovoltaic choppers are externally connected with a photovoltaic power station, and the other ends of the two energy storage choppers are respectively connected with an external energy storage, so that new energy grid connection is realized, the system occupation is reduced, the investment cost is reduced, and the construction work of an energy internet is facilitated.

(2) The energy exchanger provided by the invention realizes flexible interconnection of an alternating current side and a direct current side in a microgrid, and can be directly connected with direct current loads such as photovoltaic loads, energy storage loads, electric automobiles, electric bicycles and the like, and 220V/380V alternating current loads; the photovoltaic, energy storage and AC/DC load autonomous control at the DC side can be realized, and a flexible and economic AC/DC microgrid is formed; and the coordinated optimization operation of a distributed power supply, energy storage and AC/DC load can be realized.

(3) The energy exchanger provided by the invention adopts an integrated design, so that the early investment of micro-grid construction can be reduced, and the micro-grid energy exchanger equipment integrates energy storage bidirectional alternating current-direct current conversion, photovoltaic alternating current-direct current conversion and other primary power conversion modules and self-adaptive local management and control software, so that the total equipment investment of the micro-grid construction can be reduced.

(4) The energy exchanger provided by the invention has the advantages of high reliability and low operation and maintenance cost, and the microgrid energy exchanger can improve the safety, run stably and has low running failure rate during the period of putting the microgrid energy exchanger into operation; meanwhile, the equipment for operation and maintenance is reduced, so that the labor cost for routing inspection is reduced; the maintenance links are reduced, and the maintenance cost is effectively reduced.

(5) The energy exchanger provided by the invention has the inherent characteristic of droop characteristic, the direct current bus voltage can change along with the change of the system running state, the energy exchanger has a double energy storage structure, the double energy storage power droop control is adopted to jointly maintain the direct current bus voltage, the voltage and power deviation is restrained, and the parallel-network and off-network switching at the alternating current side is more facilitated.

Drawings

FIG. 1 is a schematic structural diagram of a multi-port intelligent micro-grid energy exchanger according to the invention;

FIG. 2 is a flow chart of a method for controlling a multi-port intelligent microgrid energy switch in accordance with the present invention;

fig. 3 is a flow chart of a specific control method for the multi-port intelligent microgrid energy switch in the invention.

Detailed Description

For a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples.

Example 1

Based on the concentrative and primary-secondary fusion ideas, the invention provides a multi-port intelligent micro-grid energy exchanger which can be integrated with photovoltaic power, an alternating current power supply, energy storage and direct current loads and alternating current loads of multiple voltage levels. Meanwhile, a multi-energy complementary operation control strategy for the energy exchanger is provided, the strategy is integrated in the energy exchanger, so that the primary and secondary integration of the whole machine is realized, and the source and load storage coordination control and energy optimization management functions between an alternating current/direct current power supply and an alternating current/direct current load can be realized; adopt two energy storage structures to maintain direct current bus voltage jointly through power droop control, be convenient for exchange the side and realize seamless and off-grid switching, provide technical support for the construction of regional energy internet in the future.

As shown in fig. 1, the multi-port smart micro grid energy exchanger provided by the present invention includes: the system comprises a photovoltaic chopper, at least two energy storage choppers, an output chopper, a master inverter, a slave inverter and a control chip;

the other end of each photovoltaic chopper is externally connected with a photovoltaic power station, and the other ends of the two energy storage choppers are respectively connected with an external energy storage;

the control chip is respectively connected with the photovoltaic chopper, each energy storage chopper, the output chopper, the host inverter and the slave inverter and used for sending control signals.

The invention provides a multiport energy exchanger structure which generates three direct current inputs, wherein one input is a photovoltaic input, and two inputs are energy storage inputs; 48/400V two-path direct current output is provided, and direct current loads such as electric automobiles, electric bicycles and the like can be directly connected; and meanwhile, 220/380V three-way alternating-current power supply interfaces are provided, wherein one way is connected with a 380V three-phase power grid, the other way is connected with a single-phase 200V local load, and the other way is connected with a 380V three-phase local load. In summary, the energy exchanger includes five dc ports and three ac ports.

As shown in fig. 2, the present invention provides a method for controlling a multi-port intelligent microgrid energy switch, comprising:

s1, the control chip respectively detects the stored energy voltage connected with each energy storage chopper through each energy storage chopper, when the stored energy voltage of any path is greater than the energy storage threshold, the energy storage chopper corresponding to the stored energy voltage greater than the energy storage threshold is started to operate in a constant direct current bus voltage mode, and S2 is executed; otherwise, detecting whether the photovoltaic power station is electrified or not through the photovoltaic chopper, charging any path of stored energy when the photovoltaic power station is electrified, and continuously detecting the voltage of the stored energy;

The control method of the multi-port intelligent micro-grid energy exchanger is specifically explained by using the following steps as shown in fig. 3:

s1, the control chip respectively detects the stored energy voltage connected with each energy storage chopper through each energy storage chopper, when the stored energy voltage of any path is greater than the energy storage threshold, the energy storage chopper corresponding to the stored energy voltage greater than the energy storage threshold is started to operate in a constant direct current bus voltage mode, and S2 is executed; otherwise, whether the photovoltaic power station has electricity is detected through the photovoltaic chopper, when the photovoltaic power station has electricity, the photovoltaic power station charges any energy storage path, and the voltage of the energy storage is continuously detected, which specifically comprises the following steps:

1) and if the voltage of any one of the two batteries is greater than a certain value, starting the fixed direct current bus voltage mode to operate, and performing the second step. If the two battery voltages do not accord with the starting condition, judging whether the photovoltaic has electricity: if the photovoltaic is electrified, the photovoltaic charges any path of battery, and when the voltage of the path is greater than a certain value, a fixed bus voltage mode is started to carry out the second step; and the photovoltaic generator is in a standby state without electricity.

2) Starting a fixed direct current bus mode to emit waves by using an energy storage chopper which operates in a mode of starting the fixed direct current bus voltage, judging whether the voltage on the direct current bus side reaches a set control target value, closing an inverter side grid-connected switch (KM 1 in the figure 1) if the voltage on the direct current bus is equal to the control target value, then performing a third step, and returning to the step (1) if the voltage on the direct current bus does not reach the control target value; wherein the control target value set in the present embodiment is 750V; the dc bus voltages DD2 and DD 3;

s2, setting an operation mode of an output chopper and judging whether the voltage on the grid side is electrified, when the voltage on the grid side is electrified, starting an operation grid-connected mode, executing S3 to send the photovoltaic power to the grid side in a maximum output mode, otherwise, starting an off-grid mode, executing S4 to send the photovoltaic power to the load side in the maximum output mode, and the method specifically comprises the following steps:

3) after the voltage of the 750V direct-current bus is established, the DD4 is started up, and the DD4 is used for fixing the low-voltage of 400V to serve as a charging pile;

4) judging the voltage of the grid side, if the voltage of the grid side is normal, closing a grid-side grid-connected switch, namely QF14 in fig. 1, and simultaneously starting the operation of a grid-connected mode by an inverter, wherein the given power value is a photovoltaic output power value; and if the voltage on the network side is abnormal, disconnecting the grid-connected switch on the network side, simultaneously starting the VF mode by the equipment, setting the given voltage value to be 220V, and then carrying out the next step.

S3, setting a grid-connected operation mode of the master inverter and the slave inverter, and determining whether the photovoltaic power station charges each energy storage based on the charge state of each energy storage, wherein the method specifically comprises the following steps:

5) and if the equipment starts a grid-connected operation mode in the step 4), the power of the photovoltaic is sent to the grid side in a maximum output mode. Firstly, setting DA1 to operate in a PQ mode to give grid-connected power, and automatically following DA1 by DA2, wherein the PQ mode is given to the starting power and the DSP is set; then, the control is divided into two conditions according to the SOC of the two batteries:

if the SOC of the battery set which is put into the operation in the fixed direct current bus mode is lower than 90%, changing the given value of grid-connected power to charge the battery by part of power until the SOC is 90%; if the SOC of the other group of batteries is lower than 90%, the batteries are also put into the operation in the fixed direct current bus mode, the power distribution coefficient is changed according to the proportion of the SOC to achieve the purpose of 'less charge and more charge', and the standby batteries are stopped after the SOCs of the two groups of batteries are both 90%.

S4, setting off-grid operation modes of the master inverter and the slave inverter, and determining the operation mode of the photovoltaic chopper and the operation state of each stored energy based on the relation between the photovoltaic power and the load power and the charge state of each stored energy, wherein the method specifically comprises the following steps:

6) if the equipment starts the off-grid VF operation mode in the step 3), the power of the photovoltaic is sent to the load side in the maximum output mode. Firstly, judging whether the SOC of the battery is more than 30% at the starting time, if the SOC of the battery is more than 30% at the starting time, setting the DA1 to operate in a VF mode, and fixing the AC voltage to 380V; the DA2 automatically follows the a1 with PQ mode power on given and DSP set. The embodiment is considered that the power of the connected load is less than 60kW, namely the DA1 does not run the voltage reduction current limiting mode, and then the control is carried out according to the following two conditions:

if the power of the photovoltaic is larger than the load power, the remaining part is set for charging the battery, after the SOC of the battery reaches 90%, the voltage of a direct current bus is raised by the photovoltaic remaining power, the photovoltaic enters a power-limiting operation mode, the given value of the power limiting is equal to the load power, and the charging condition and the charging method are judged to be the same as those in the grid-connected state in the process.

If the photovoltaic power is smaller than the load power, the other path of battery is started to straighten the bus together, the two paths of batteries discharge the load according to droop control, the SOC of one path of battery is lower than 30%, the branch circuit of the path of battery is stopped to work, if the SOC of the two paths of batteries is lower than 30%, the equipment is in a standby state and returns to the step 1), and the grid connection of the network side voltage is waited. In the process, 1) one group of batteries works, and one group of batteries is discharged; 2) the two groups of batteries work and the discharge power is divided equally.

It should be noted that: firstly, the SOC of the battery in the fixed value mother link is more than 30%, and the VF mode can be operated (when only one group of batteries works, one group of batteries is judged, and when two groups of batteries work, two groups of batteries are judged); and secondly, if the SOC of the battery is less than 30% at the starting time, the VF mode cannot be operated, and the battery can only be charged by the normal operation of the power grid in the PQ mode.

7) And carrying out island detection on the equipment in grid-connected operation control, and if an island occurs, switching to the VF mode according to over-voltage and under-voltage or over-frequency and under-frequency.

8) If the power grid is recovered to be normal in the off-grid operation control of the equipment, the equipment starts to synchronize and is switched to a grid-connected operation mode.

The switches QF10, QF11 and QF12 on the load side are opened and closed according to actual needs.

Example 2

The invention provides a concrete structure of an energy exchanger, which is shown in figure 1, and the device is in a double-and-double structure formed by 6 single converters, wherein DD1, DD2, DD3 and DD4 are respectively a photovoltaic chopper, a first energy storage chopper, a second energy storage chopper and a 400V output chopper, DA1 and DA2 are respectively a master inverter and a slave inverter, are three-phase three-wires, are changed into three-phase four-wires by a transformer, and can be connected with a single-phase load. The 48V direct current module input is single-phase alternating current 220V input. Switches QF1 and QF2 are input and output switches of the photovoltaic chopper, switches QF2 and QF5 are input and output switches of the first energy storage chopper, switches QF3 and QF6 are input and output switches of the second energy storage chopper, switches QF9 and QF10 are input and output switches of the 400V output chopper, switch QF7 is a direct-current input switch of the master inverter, switch QF8 is a direct-current input switch of the slave inverter, QF11 is a three-phase four-wire alternating-current load switch, QF12 is a single-phase alternating-current load switch, QF13 is an output switch of direct current 48V, QF14 is a grid-side grid switch, and switch KM1 is an inverter-side grid-connected switch for grid-connected and disconnected switching.

The eight-port intelligent micro-grid energy exchanger framework oriented to the regional energy Internet can be directly incorporated into a 380V power grid, photovoltaic power is connected, two paths of energy storage are carried out, direct current loads of an electric automobile (400V), an electric bicycle (48V) and the like and 220V/380V alternating current loads are carried out; the photovoltaic inverter, the energy storage bidirectional converter and other primary converter equipment are highly integrated, an alternating current and direct current interconnected micro-grid can be quickly built, and the early investment of engineering construction is reduced.

According to the operation control strategy of the alternating current-direct current hybrid micro-grid based on the energy exchanger, double energy storage power droop control is adopted to maintain the voltage of a direct current bus together, voltage and power deviation is restrained, and the operation control strategy is more beneficial to switching between a grid connection and a grid disconnection at an alternating current side and realizes coordination control of source, load and storage.

Example 3

In an embodiment, the determining module includes:

In an embodiment, the grid-connected module includes:

In an embodiment, the off-grid module includes:

In an embodiment, the control system is disposed on a control chip, and the control chip is respectively connected with the photovoltaic chopper, each energy storage chopper, the output chopper, the master inverter and the slave inverter.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.

Claims

1. A multi-port smart microgrid energy switch, comprising: the system comprises a photovoltaic chopper, at least two energy storage choppers, an output chopper, a master inverter, a slave inverter and a control chip;

2. The energy switch of claim 1, wherein the first dc port is connected to a 48V dc load.

3. The energy switch of claim 1, wherein the second dc port is connected to a 400V dc load.

4. The energy exchanger of claim 1, wherein the first ac port is connected to the grid via an inverter-side grid tie switch and a grid-side grid tie switch in sequence.

5. A control method for the multi-port smart micro-grid energy switch according to claims 1-4, characterized by comprising:

6. The control method according to claim 5, wherein the energy storage voltage > energy storage threshold corresponds to an energy storage chopper start constant DC bus voltage mode operation and executing S2, comprising:

7. The control method of claim 5, wherein said setting an operating mode of the output chopper comprises:

the low voltage is 400V.

8. The control method of claim 5, wherein the step of starting a grid-connected operation mode when the grid-side voltage is charged, executing step S3 to send the photovoltaic power to the grid side in a maximum output mode, and otherwise, starting an off-grid operation mode, executing step S4 to send the photovoltaic power to the load side in the maximum output mode comprises:

9. The control method of claim 5, wherein setting a grid-tie mode of operation for the master inverter and the slave inverter comprises:

10. The control method of claim 5, wherein determining whether the photovoltaic power plant is charging each stored energy based on each stored energy state of charge comprises:

11. The control method of claim 5, wherein prior to initiating the off-grid mode, comprising:

12. The control method of claim 5, wherein setting an off-grid mode of operation for the master inverter and the slave inverter comprises:

13. The control method according to claim 5, wherein the determining the operation mode of the photovoltaic chopper and the operation state of each stored energy based on the relation between the photovoltaic power and the load power and the state of charge of each stored energy comprises:

14. The control method of claim 5, wherein setting a grid-tie mode of operation for the master inverter and the slave inverter, further comprises:

15. The control method of claim 5, wherein setting an off-grid mode of operation for the master inverter and the slave inverter, further comprises:

16. A control system for the multi-port smart micro grid energy switch of claims 1-4, comprising:

17. The control system of claim 16, wherein the determination module comprises:

18. The control system of claim 16, wherein the grid tie module comprises:

19. The control system of claim 16, wherein the off-grid module comprises:

20. The control system of claim 16, wherein the control system is disposed on a control chip, the control chip being connected to the photovoltaic chopper, each energy storage chopper, the output chopper, the master inverter, and the slave inverter, respectively.