CN110912169A - Design method and topological structure of alternating current-direct current micro-grid - Google Patents
Design method and topological structure of alternating current-direct current micro-grid Download PDFInfo
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- 238000007599 discharging Methods 0.000 claims description 4
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J5/00—Circuit arrangements for transfer of electric power between ac networks and dc networks
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E70/00—Other energy conversion or management systems reducing GHG emissions
- Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
Abstract
The invention provides an alternating current-direct current microgrid design method and a topological structure, and relates to the field of microgrid energy conservation, wherein the topological structure comprises the following components: a DC/AC bi-directional converter; a photovoltaic power generation unit; an energy storage unit; a DC/DC converter; a direct current bus; an alternating current bus; a transformer; a data center station; the external power grid is connected with the primary side of the transformer; the secondary side of the transformer is connected with an alternating current bus; the alternating current bus is connected with the alternating current side of the direct current/alternating current bidirectional converter; the photovoltaic power generation unit and the energy storage unit are connected with the direct current bus; the direct current side of the direct current/alternating current bidirectional converter is connected with a direct current bus; the input side of the DC/DC converter is connected with a DC bus; the output side of the DC/DC converter is connected to the data center station and supplies power to the data center station. Renewable energy is fully utilized, meanwhile, a micro-grid system in the prior art is improved, a UPS (uninterrupted power supply) is omitted, the energy utilization rate is improved, and the waste of a standby battery is reduced.
Description
Technical Field
The invention relates to the technical field of energy conservation and energy storage of a microgrid, in particular to an alternating current-direct current microgrid topological structure and a design method.
Background
With the increase of a large amount of dc loads, the conventional ac bus and UPS combined power supply mode becomes single and inefficient, so it is necessary to discuss the ac/dc microgrid power supply system in the intelligent energy station to deal with the access of a large amount of dc loads and power supplies.
With the increasingly severe environmental problems such as depletion of fossil energy and global warming, preferential development and utilization of renewable energy such as solar energy and the like are of great significance in changing energy structures, improving energy efficiency and guaranteeing energy safety in China.
The high-capacity battery energy storage technology is rapidly developed and applied in recent years, the technology gradually tends to be reliable and mature, a batch of advanced and reliable energy storage battery technologies appear, and the high-capacity battery energy storage technology is preliminarily applied to the aspects of improving the capacity of a power grid for receiving an intermittent power supply, frequency modulation of a power system, peak clipping and valley filling, stabilizing the power fluctuation of the intermittent power supply and the like.
The intelligent energy station has the advantages that the power consumption of loads in the intelligent energy station is large, so that the light storage alternating current-direct current micro-grid system is built in the energy station, renewable energy and an energy storage system are fully utilized, a reasonable energy management principle and an operation control strategy are formulated for the light storage alternating current-direct current micro-grid, the renewable energy can be consumed to reduce the power consumption of the station, and meanwhile, the power supply reliability of the station loads is improved.
Disclosure of Invention
In view of the above, the present invention provides an ac/dc microgrid design method and topology structure to fully utilize renewable energy, and improve a microgrid system in the prior art, thereby reducing UPS uninterruptible power supplies and improving energy utilization.
In a first aspect, an embodiment of the present invention provides an ac/dc microgrid topology, including: a DC/AC bi-directional converter; a photovoltaic power generation unit; an energy storage unit; a DC/DC converter; a direct current bus; an alternating current bus; a transformer; a data center station;
an external power grid is connected with the primary side of the transformer;
the secondary side of the transformer is connected with the alternating current bus;
the alternating current bus is connected with the alternating current side of the direct current/alternating current bidirectional converter;
the photovoltaic power generation unit and the energy storage unit are connected with the direct current bus;
the direct current side of the direct current/alternating current bidirectional converter is connected with the direct current bus;
the input side of the DC/DC converter is connected with the DC bus;
the output side of the DC/DC converter is connected to the data center station and supplies power to the data center station.
Preferably, the voltage of the direct current bus is 750DC, and the voltage of the alternating current bus is 380 AC;
the input side voltage of the direct current/direct current converter is 750 DC;
the output side voltage of the direct current/direct current converter is 220 DC;
the alternating-current side voltage of the alternating-current bus and the direct-current/alternating-current bidirectional converter is 380 AC;
the direct-current side voltage of the direct-current/alternating-current bidirectional converter is 750 DC.
On the other hand, the invention provides an alternating current-direct current microgrid design method, which is applied to a first server and specifically comprises the following steps:
s1: judging whether an external power grid supplies energy to the alternating current-direct current micro-grid;
if yes, the alternating current-direct current microgrid is not in an island operation state, and step S101 is executed;
if not, the alternating current-direct current microgrid is in an island operation state, and the step S102 is executed:
s101: determining that the alternating current-direct current microgrid is in a peak time period or a low-valley time period according to peak and low-valley time periods defined by a local power grid company;
if the energy storage unit is in a peak time period, acquiring an energy storage unit capacity margin SOC, photovoltaic power generation power and a local station electric load of the energy storage unit, and judging energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid on the basis of the energy storage unit capacity margin SOC, the photovoltaic power generation power and the local station electric load;
if the energy storage unit is in the valley time period, acquiring the output power of the photovoltaic power generation unit and the charging power of the energy storage unit, and judging the energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid based on the charging power of the photovoltaic power generation unit and the charging power of the energy storage unit;
s102: and acquiring a voltage value of the direct current bus voltage under the island operation, and determining the energy flow of the energy storage unit and the photovoltaic power generation unit based on the voltage value of the direct current bus voltage.
Preferably, the step of obtaining the energy storage unit capacity margin SOC, the photovoltaic power generation power, and the local station electrical load of the energy storage unit, and determining the energy flow among the energy storage unit, the photovoltaic power generation unit, and the external power grid based on the energy storage unit capacity margin SOC, the photovoltaic power generation power, and the local station electrical load includes:
acquiring an energy storage unit capacity margin SOC threshold value and the energy storage unit capacity margin SOC, and judging whether the energy storage unit capacity margin SOC is larger than the energy storage unit capacity margin SOC threshold value or not;
if the current is larger than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter to work in an inversion state, a discharge instruction of the energy storage unit is sent to enable the energy storage unit to work in a discharge state, a photovoltaic power generation instruction is sent to enable the photovoltaic power generation unit to generate power, and energy is output to an external power grid to meet peak clipping requirements in peak periods;
if the current is less than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter to work in an inversion state, the energy storage unit works in a discharge state to enable the energy storage unit not to work, a photovoltaic power generation instruction is sent to enable the photovoltaic power generation unit to generate power, and energy is input from the external power grid to meet the requirement of the power load.
Preferably, the step of obtaining the output power of the photovoltaic power generation unit and the charging power of the energy storage unit and determining the energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid based on the charging power of the photovoltaic power generation unit and the charging power of the energy storage unit includes:
acquiring the charging power of the energy storage unit and the generating power of the photovoltaic power generation unit, and judging whether the charging power of the energy storage unit is greater than the generating power of the photovoltaic power generation unit;
if the current is larger than the preset current, sending a rectification instruction to enable the direct current/alternating current bidirectional converter to work in a rectification state, wherein the charging power of the energy storage unit is provided by the photovoltaic power generation unit and the alternating current bus;
if the voltage is less than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter to work in an inversion state, and the charging power of the energy storage unit is provided by the photovoltaic power generation unit.
Preferably, the step of acquiring a voltage value of the dc bus voltage in the islanding operation and determining the energy flow of the energy storage unit and the photovoltaic power generation unit based on the voltage value of the dc bus voltage includes:
acquiring real-time voltage of a direct current bus, a first threshold value of the voltage of the direct current bus and a second threshold value of the voltage of the direct current bus, wherein the second threshold value of the direct current bus is larger than the first threshold value of the direct current bus;
judging the relation between the real-time voltage of the direct current bus and a first threshold value and a second threshold value of the direct current bus;
if the real-time voltage of the direct current bus is between the first threshold value of the direct current bus and the second threshold value of the direct current bus, the energy storage unit works in a charging state;
and if the real-time voltage of the direct current bus exceeds the second threshold value of the direct current bus, controlling the power generation power of the photovoltaic power generation unit so that the real-time voltage of the direct current bus is equal to the second threshold value of the direct current bus.
Preferably, the step of sending an inversion instruction to enable the dc/ac bidirectional converter to work in an inversion state, sending an energy storage unit discharge instruction to enable the energy storage unit to work in a discharge state, sending a photovoltaic power generation instruction to enable the photovoltaic power generation unit to generate power, and outputting energy to an external power grid to meet peak clipping requirements in peak hours;
satisfies the following relation:
Pg+Plac＝Pbat-c(f)+Ppv-Pldc(SOC＞25％)；
Ppv-the power generated by the photovoltaic power generation unit,
Pbat-c(f)-the energy storage unit is charged (discharged) with electric power, so as to be positive for discharging and negative for charging;
Pldc-dc bus load power;
Plac-ac bus load power;
Pgthe external power grid exchanges power with the alternating current-direct current microgrid system, so that power obtained from the external power grid is negative, and power supplied to the external power grid is positive;
the energy storage unit capacity margin SOC is 25% of the threshold value.
Preferably, the step of sending an inversion command to enable the dc/ac bidirectional converter to operate in an inversion state and the energy storage unit to operate in a discharge state to enable the energy storage unit not to operate, and sending a photovoltaic power generation command to enable the photovoltaic power generation unit to generate power, where the step of inputting energy from the external power grid to meet the demand of the power load includes:
satisfies the following relation:
Pg+Plac＝Ppv-Pldc；
Ppv-the generated power of the photovoltaic power generation unit;
Pldc-dc bus load power;
Plac-ac bus load power;
Pgand exchanging power between the external power grid and the alternating current and direct current microgrid system, so that the power obtained from the external power grid is negative, and the power supplied to the external power grid is positive.
Preferably, the step of sending a rectification command to enable the dc/ac bidirectional converter to operate in a rectification state, and the step of providing the charging power of the energy storage unit by the photovoltaic power generation unit and the ac bus includes:
satisfies the following relation:
Pg+Plac＝Pbat-c(f)+Ppv-Pldc；
Ppv-the power generated by the photovoltaic power generation unit,
Pbat-c(f)-the energy storage unit is charged (discharged) with electric power, so as to be positive for discharging and negative for charging;
Pldc-DC busLoad power;
Plac-ac bus load power;
Pgand exchanging power between the external power grid and the alternating current and direct current microgrid system, so that the power obtained from the external power grid is negative, and the power supplied to the external power grid is positive.
Preferably, the step of sending an inversion command to enable the dc/ac bidirectional converter to operate in an inversion state, and the step of providing the charging power of the energy storage unit by the photovoltaic power generation unit includes:
Pg+Plac＝Ppv-Pldc；
Ppv-the generated power of the photovoltaic power generation unit;
Pldc-dc bus load power;
Plac-ac bus load power;
Pgand exchanging power between the external power grid and the alternating current and direct current microgrid system, so that the power obtained from the external power grid is negative, and the power supplied to the external power grid is positive.
The embodiment of the invention has the following beneficial effects: the invention provides an alternating current-direct current microgrid design method and a topological structure, wherein the topological structure comprises the following components: a DC/AC bi-directional converter; a photovoltaic power generation unit; an energy storage unit; a DC/DC converter; a direct current bus; an alternating current bus; a transformer; a data center station; the external power grid is connected with the primary side of the transformer; the secondary side of the transformer is connected with an alternating current bus; the alternating current bus is connected with the alternating current side of the direct current/alternating current bidirectional converter; the photovoltaic power generation unit and the energy storage unit are connected with the direct current bus; the direct current side of the direct current/alternating current bidirectional converter is connected with a direct current bus; the input side of the DC/DC converter is connected with a DC bus; the output side of the DC/DC converter is connected to the data center station and supplies power to the data center station. Renewable energy is fully utilized, meanwhile, a micro-grid system in the prior art is improved, a UPS (uninterrupted power supply) is omitted, and the energy utilization rate is improved.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a structural diagram of an ac/dc microgrid topology according to an embodiment of the present invention;
fig. 2 is a structural diagram of another ac/dc microgrid topology according to an embodiment of the present invention;
fig. 3 is a schematic diagram of the output of a photovoltaic power generation unit in an isolated island operation of an ac/dc microgrid topology structure provided by the embodiment of the present invention;
fig. 4 is an energy flow diagram of a first ac/dc microgrid design structure according to an embodiment of the present invention;
fig. 5 is an energy flow diagram of a second ac/dc microgrid design structure according to an embodiment of the present invention;
fig. 6 is an energy flow diagram of a third ac/dc microgrid design structure according to an embodiment of the present invention;
fig. 7 is an energy flow diagram of a fourth ac/dc microgrid design structure according to an embodiment of the present invention.
Icon: 1 — external grid; 2-a transformer; 3-a dc/ac bi-directional converter; 4-direct current bus; 5-a dc/dc converter; 6, an energy storage unit.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Based on the fact that a UPS is used for supplying power to a data center in the prior art and the power grid structure is complicated, the AC/DC micro-grid topological structure and the design method provided by the embodiment of the invention can fully utilize renewable energy sources, and meanwhile, the micro-grid system in the prior art is improved, so that the UPS is reduced, and the energy utilization rate is improved.
To facilitate understanding of the embodiment, first, a detailed description is given to an ac/dc microgrid topology disclosed in the embodiment of the present invention:
as shown in fig. 1, the present invention provides an ac/dc microgrid topology, including: a DC/AC bidirectional converter 3; a photovoltaic power generation unit; an energy storage unit 6; a DC/DC converter 5; a direct current bus 5; an alternating current bus; a transformer; a data center station;
an external power grid 1 is connected with the primary side of the transformer;
the secondary side of the transformer is connected with the alternating current bus;
the alternating current bus is connected with the alternating current side of the direct current/alternating current bidirectional converter 3;
the photovoltaic power generation unit and the energy storage unit 6 are connected with the direct current bus 5;
the direct current side of the direct current/alternating current bidirectional converter 3 is connected with the direct current bus 5;
the input side of the DC/DC converter 5 is connected with the DC bus 5;
the output side of the dc/dc converter 5 is connected to the data centre station and supplies power to the data centre station.
It should be noted that, in the embodiment provided by the present invention, the voltage of the direct current bus 5 is 750DC, and the voltage of the alternating current bus is 380 AC;
the input side voltage of the DC/DC converter 5 is 750 DC;
the output side voltage of the DC/DC converter 5 is 220 DC;
the alternating-current side voltage of the alternating-current bus and the direct-current/alternating-current bidirectional converter 3 is 380 AC;
the direct-current side voltage of the direct-current/alternating-current bidirectional converter is 750 DC.
In another embodiment provided by the present invention, as shown in fig. 2, two transformers may be provided, placing the dc load separately from the ac load;
in the embodiment provided by the invention, the number of the alternating current/alternating current bidirectional converters is 4, and the number of the direct current/direct current converters 5 is 4
Example two:
the invention provides an alternating current-direct current microgrid design method, which is applied to a first server and specifically comprises the following steps:
s1: judging whether the external power grid 1 supplies energy to the alternating current-direct current micro-grid;
if yes, the alternating current-direct current microgrid is not in an island operation state, and step S101 is executed;
if not, the alternating current-direct current microgrid is in an island operation state, and the step S102 is executed:
s101: : determining that the alternating current-direct current microgrid is in a peak time period or a low-valley time period according to peak and low-valley time periods defined by a local power grid company;
if the energy storage unit is in the peak time, acquiring the energy storage unit capacity margin SOC, the photovoltaic power generation power and the local station electric load of the energy storage unit 6, and judging the energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid based on the energy storage unit capacity margin SOC, the photovoltaic power generation power and the local station electric load;
the method comprises the following specific steps:
acquiring a capacity margin SOC threshold value of an energy storage unit 6 and a capacity margin SOC of the energy storage unit 6, and judging whether the capacity margin SOC of the energy storage unit 6 is larger than the capacity margin SOC threshold value of the energy storage unit 6;
as shown in fig. 4, if the current is greater than the peak current, an inversion instruction is sent to enable the dc/ac bidirectional converter to operate in an inversion state, a discharge instruction of the energy storage unit is sent to enable the energy storage unit to operate in a discharge state, and a photovoltaic power generation instruction is sent to enable the photovoltaic power generation unit to generate power and output energy to an external power grid to meet peak clipping requirements during peak hours;
in the embodiment provided by the invention, the following relational expression is satisfied:
Pg+Plac＝Pbat-c(f)+Ppv-Pldc(SOC＞25％)；
Ppv-the power generated by the photovoltaic power generation unit,
Pbat-c(f)the energy storage unit 6 charges (discharges) electric power to discharge positively and charges negatively;
Pldc-dc bus 5 load power;
Plac-ac bus load power;
Pgthe external power grid 1 exchanges power with the alternating current-direct current microgrid system, so that power obtained from the external power grid 1 is negative, and power supplied to the external power grid 1 is positive;
the capacity margin SOC of the energy storage unit 6 is 25% of the threshold value.
If the current is less than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter to work in an inversion state, the energy storage unit works in a discharge state to enable the energy storage unit not to work, a photovoltaic power generation instruction is sent to enable the photovoltaic power generation unit to generate power, and energy is input from the external power grid to meet the requirement of the power load.
As shown in fig. 5, in the embodiment of the present invention, the following relationship is satisfied:
Pg+Plac＝Ppv-Pldc；
Ppv-the generated power of the photovoltaic power generation unit;
Pldc-DC bus 5 load power；
Plac-ac bus load power;
Pgthe external power grid 1 exchanges power with the alternating current-direct current microgrid system, so that power obtained from the external power grid 1 is negative, and power supplied to the external power grid 1 is positive.
If the energy storage system is in a low-valley period, acquiring the output power of the photovoltaic power generation unit and the charging power of the energy storage unit 6, and judging the energy flow among the energy storage unit 6, the photovoltaic power generation unit and the external power grid 1 based on the charging power of the photovoltaic power generation unit and the energy storage unit 6;
it should be noted that, at this time, the power grid is in the valley operation, and the method specifically includes the following steps:
acquiring the charging power of the energy storage unit 6 and the generating power of the photovoltaic power generation unit, and judging whether the charging power of the energy storage unit 6 is greater than the generating power of the photovoltaic power generation unit;
if the voltage is greater than the preset value, sending a rectification instruction to enable the direct current/alternating current bidirectional converter 3 to work in a rectification state, wherein the charging power of the energy storage unit 6 is provided by the photovoltaic power generation unit and the alternating current bus;
it should be noted that, at this time, the photovoltaic power generation power cannot satisfy the power supply power of the energy storage unit 6, and specifically satisfies the following relationship:
as shown in FIG. 6, Pg+Plac＝Pbat-c(f)+Ppv-Pldc；
Ppv-the power generated by the photovoltaic power generation unit,
Pbat-c(f)the energy storage unit 6 charges (discharges) electric power to discharge positively and charges negatively;
Pldc-dc bus 5 load power;
Plac-ac bus load power;
Pgthe external power grid 1 exchanges power with the alternating current-direct current microgrid system, so that power obtained from the external power grid 1 is negative, and power supplied to the external power grid 1 is positive.
If the voltage is smaller than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter 3 to work in an inversion state, and the charging power of the energy storage unit 6 is provided by the photovoltaic power generation unit.
It should be noted that, at this time, the output power of the photovoltaic power generation unit is sufficient to satisfy the charging power of the energy storage unit 6, and specifically satisfies the following relationship:
as shown in FIG. 7, Pg+Plac＝Ppv-Pldc；
Ppv-the generated power of the photovoltaic power generation unit;
Pldc-dc bus 5 load power;
Plac-ac bus load power;
Pgthe external power grid 1 exchanges power with the alternating current-direct current microgrid system, so that power obtained from the external power grid 1 is negative, and power supplied to the external power grid 1 is positive.
As shown in fig. 3, S102: and acquiring a voltage value of the voltage of the direct current bus 5 under the island operation, and determining the energy flow of the energy storage unit 6 and the photovoltaic power generation unit based on the voltage value of the voltage of the direct current bus 5.
The embodiment provided by the invention specifically comprises the following steps:
acquiring real-time voltage of a direct current bus 5, a first voltage threshold value of the direct current bus 5 and a second voltage threshold value of the direct current bus 5, wherein the second voltage threshold value of the direct current bus 5 is larger than the first voltage threshold value of the direct current bus 5;
judging the relation between the real-time voltage of the direct current bus 5 and a first threshold value of the direct current bus 5 and a second threshold value of the direct current bus 5;
if the real-time voltage of the direct current bus 5 is between the first threshold value of the direct current bus 5 and the second threshold value of the direct current bus 5, the energy storage unit 6 works in a charging state;
and if the real-time voltage of the direct current bus 5 exceeds a second threshold value of the direct current bus 5, controlling the power generation power of the photovoltaic power generation unit so that the real-time voltage of the direct current bus 5 is equal to the second threshold value of the direct current bus 5.
Specifically, the voltage value of the dc bus 5 is 1.02 times of the first threshold value of the dc bus 5, and the voltage value of the dc bus 5 is 1.05 times of the second threshold value of the dc bus 5.
Unless specifically stated otherwise, the relative steps, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present invention. The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the system and the apparatus described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In addition, in the description of the embodiments of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Unless specifically stated otherwise, the relative steps, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present invention. The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Claims (10)
1. An ac/dc microgrid topology, comprising: a DC/AC bi-directional converter; a photovoltaic power generation unit; an energy storage unit; a DC/DC converter; a direct current bus; an alternating current bus; a transformer; a data center station;
an external power grid is connected with the primary side of the transformer;
the secondary side of the transformer is connected with the alternating current bus;
the alternating current bus is connected with the alternating current side of the direct current/alternating current bidirectional converter;
the photovoltaic power generation unit and the energy storage unit are connected with the direct current bus;
the direct current side of the direct current/alternating current bidirectional converter is connected with the direct current bus;
the input side of the DC/DC converter is connected with the DC bus;
the output side of the DC/DC converter is connected to the data center station and supplies power to the data center station.
2. The AC-DC microgrid topology structure of claim 1, wherein a voltage of the DC bus is 750DC, and a voltage of the AC bus is 380 AC;
the input side voltage of the direct current/direct current converter is 750 DC;
the output side voltage of the direct current/direct current converter is 220 DC;
the alternating-current side voltage of the alternating-current bus and the direct-current/alternating-current bidirectional converter is 380 AC;
the direct-current side voltage of the direct-current/alternating-current bidirectional converter is 750 DC.
3. The design method of the alternating current-direct current microgrid, which is applied to the first server, is implemented according to the following steps:
s1: judging whether an external power grid supplies energy to the alternating current-direct current micro-grid;
if yes, the alternating current-direct current microgrid is not in an island operation state, and step S101 is executed;
if not, the alternating current-direct current microgrid is in an island operation state, and the step S102 is executed:
s101: determining that the alternating current-direct current microgrid is in a peak time period or a low-valley time period according to peak and low-valley time periods defined by a local power grid company;
if the energy storage unit is in a peak time period, acquiring an energy storage unit capacity margin SOC, photovoltaic power generation power and a local station electric load of the energy storage unit, and judging energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid on the basis of the energy storage unit capacity margin SOC, the photovoltaic power generation power and the local station electric load;
if the energy storage unit is in the valley time period, acquiring the output power of the photovoltaic power generation unit and the charging power of the energy storage unit, and judging the energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid based on the charging power of the photovoltaic power generation unit and the charging power of the energy storage unit;
s102: and acquiring a voltage value of the direct current bus voltage under the island operation, and determining the energy flow of the energy storage unit and the photovoltaic power generation unit based on the voltage value of the direct current bus voltage.
4. The method of claim 3, wherein the step of obtaining the energy storage unit capacity margin SOC, the photovoltaic power generation power and the local station electric load of the energy storage unit and determining the energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid based on the energy storage unit capacity margin SOC, the photovoltaic power generation power and the local station electric load comprises:
acquiring an energy storage unit capacity margin SOC threshold value and the energy storage unit capacity margin SOC, and judging whether the energy storage unit capacity margin SOC is larger than the energy storage unit capacity margin SOC threshold value or not;
if the current is larger than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter to work in an inversion state, a discharge instruction of the energy storage unit is sent to enable the energy storage unit to work in a discharge state, a photovoltaic power generation instruction is sent to enable the photovoltaic power generation unit to generate power, and energy is output to an external power grid to meet peak clipping requirements in peak periods;
if the current is less than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter to work in an inversion state, the energy storage unit works in a discharge state to enable the energy storage unit not to work, a photovoltaic power generation instruction is sent to enable the photovoltaic power generation unit to generate power, and energy is input from the external power grid to meet the requirement of the power load.
5. The method of claim 3, wherein the step of obtaining the photovoltaic power generation unit output power and the energy storage unit charging power to determine the energy flow among the energy storage unit, the photovoltaic power generation unit and the external power grid based on the photovoltaic power generation unit and the energy storage unit charging power comprises:
acquiring the charging power of the energy storage unit and the generating power of the photovoltaic power generation unit, and judging whether the charging power of the energy storage unit is greater than the generating power of the photovoltaic power generation unit;
if the current is larger than the preset current, sending a rectification instruction to enable the direct current/alternating current bidirectional converter to work in a rectification state, wherein the charging power of the energy storage unit is provided by the photovoltaic power generation unit and the alternating current bus;
if the voltage is less than the preset value, an inversion instruction is sent to enable the direct current/alternating current bidirectional converter to work in an inversion state, and the charging power of the energy storage unit is provided by the photovoltaic power generation unit.
6. The method according to claim 3, wherein the step of obtaining the voltage value of the DC bus voltage in islanded operation and determining the energy flow of the energy storage unit and the photovoltaic power generation unit based on the voltage value of the DC bus voltage comprises:
acquiring real-time voltage of a direct current bus, a first threshold value of the voltage of the direct current bus and a second threshold value of the voltage of the direct current bus, wherein the second threshold value of the direct current bus is larger than the first threshold value of the direct current bus;
judging the relation between the real-time voltage of the direct current bus and a first threshold value and a second threshold value of the direct current bus;
if the real-time voltage of the direct current bus is between the first threshold value of the direct current bus and the second threshold value of the direct current bus, the energy storage unit works in a charging state;
and if the real-time voltage of the direct current bus exceeds the second threshold value of the direct current bus, controlling the power generation power of the photovoltaic power generation unit so that the real-time voltage of the direct current bus is equal to the second threshold value of the direct current bus.
7. The method according to claim 4, wherein the step of sending an inversion command to enable the dc/ac bi-directional converter to operate in an inversion state, sending an energy storage unit discharge command to enable the energy storage unit to operate in a discharge state, sending a photovoltaic power generation command to enable the photovoltaic power generation unit to generate power, and outputting energy to an external power grid to meet peak clipping requirements during peak hours;
satisfies the following relation:
Pg+Plac＝Pbat-c(f)+Ppv-Pldc(SOC＞25％)；
Ppv-the power generated by the photovoltaic power generation unit,
Pbat-c(f)-the energy storage unit is charged (discharged) with electric power, so as to be positive for discharging and negative for charging;
Pldc-dc bus load power;
Plac-ac bus load power;
Pgthe external power grid exchanges power with the alternating current-direct current microgrid system, so that power obtained from the external power grid is negative, and power supplied to the external power grid is positive;
the energy storage unit capacity margin SOC is 25% of the threshold value.
8. The method according to claim 4, wherein the step of sending an inversion command to enable the dc/ac bi-directional converter to operate in an inversion state and the energy storage unit to operate in a discharge state to disable the energy storage unit, and sending a photovoltaic power generation command to enable the photovoltaic power generation unit to generate power, and the step of inputting energy from the external power grid to meet the demand of a power load comprises:
satisfies the following relation:
Pg+Plac＝Ppv-Pldc；
Ppv-the generated power of the photovoltaic power generation unit;
Pldc-dc bus load power;
Plac-ac bus load power;
Pgand exchanging power between the external power grid and the alternating current and direct current microgrid system, so that the power obtained from the external power grid is negative, and the power supplied to the external power grid is positive.
9. The method of claim 5, wherein the step of sending a rectification command to operate the dc/ac bi-directional converter in a rectification state, the step of providing the charging power of the energy storage unit by the photovoltaic power generation unit and the ac bus comprises:
satisfies the following relation:
Pg+Plac＝Pbat-c(f)+Ppv-Pldc；
Ppv-the power generated by the photovoltaic power generation unit,
Pbat-c(f)-the energy storage unit is charged (discharged) with electric power, so as to be positive for discharging and negative for charging;
Pldc-dc bus load power;
Plac-ac bus load power;
Pgand exchanging power between the external power grid and the alternating current and direct current microgrid system, so that the power obtained from the external power grid is negative, and the power supplied to the external power grid is positive.
10. The method according to claim 5, wherein the step of sending an inversion command to operate the dc/ac bi-directional converter in an inversion state, the step of providing the charging power of the energy storage unit by the photovoltaic power generation unit comprises:
Pg+Plac＝Ppv-Pldc；
Ppv-the generated power of the photovoltaic power generation unit;
Pldc-dc bus load power;
Plac-ac bus load power;
Pgand exchanging power between the external power grid and the alternating current and direct current microgrid system, so that the power obtained from the external power grid is negative, and the power supplied to the external power grid is positive.
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