CN112117776A - Charging station system based on solid-state transformer - Google Patents
Charging station system based on solid-state transformer Download PDFInfo
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- CN112117776A CN112117776A CN201910544884.XA CN201910544884A CN112117776A CN 112117776 A CN112117776 A CN 112117776A CN 201910544884 A CN201910544884 A CN 201910544884A CN 112117776 A CN112117776 A CN 112117776A
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- direct current
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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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- 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
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention provides a charging station system based on a solid-state transformer, which comprises: the input side of the solid-state transformer is connected with a power distribution network, and the output side of the solid-state transformer is connected with at least one direct current bus; the direct current bus is connected with at least one isolated charger and a non-isolated charger. The charging station system has higher efficiency, does not need to be provided with additional electric energy quality management equipment, can reduce power loss, reduces cost and the like.
Description
Technical Field
The present invention relates to a charging station system, and more particularly, to a charging station system based on a solid-state transformer.
Background
With the increasing demand of green intelligent Power, the voltage class of Power Electronic converters (PET), also called Solid State Transformers (SST), is gradually expanding from the traditional mainstream low voltage mains (220V/380V) to the medium voltage distribution network (2.4kV/35kV), so that Power Electronic devices are increasingly applied to the medium voltage system. Meanwhile, with the rapid development of internet data centers and the electric automobile industry, the demand for direct current power consumption is increasing day by day, and the requirements for application diversity and system architecture diversity require that the converter design is easy to expand, so that the series-parallel combination of a plurality of power electronic converters, i.e., the combined power converter, becomes an effective solution, and a direct current networking architecture based on the combined power converter (such as SST) becomes a key point of attention.
Fig. 1 shows a networking architecture based on a low-voltage ac bus in the prior art. The medium-voltage alternating-current voltage (for example, 2.4-35 kV) of the power distribution network is reduced by the transformer to form a low-voltage (for example, 380V) alternating-current bus. Direct-current loads such as a Photovoltaic (PV), a wind power system, an energy storage Battery (Battery), a Charger (Charger) and the like are hung on a low-voltage alternating-current bus through an alternating-current-direct-current (hereinafter, simply referred to as an 'AC/DC') and direct-current-direct-current (hereinafter, simply referred to as a 'DC/DC') two-stage converter; AC loads such as motors are connected to a low-voltage AC bus via AC/DC and DC-AC (hereinafter, simply referred to as "DC/AC") two-stage converters. In addition, a Power Quality regulator (PQC) is required to be directly hung on the low-voltage ac bus for Power Quality control.
However, the networking architecture shown in fig. 1 has disadvantages in that:
1) medium voltage ac bus needs to be stepped down by medium voltage transformer, which has large volume and weight, and generally needs independent transformer room for safety.
2) Due to networking based on 380V low-voltage alternating voltage, PQC and other equipment need to be installed for power quality management.
3) The direct current load and the alternating current load need to be subjected to voltage conversion through two stages of converters, and the efficiency is low.
4) In the occasions such as the occasions with the requirement of quick charging of the electric automobile, the current of the cable is large, the required cable is thick, the unit price is high, and the manufacturing cost and the construction cost are high when the low-voltage cable is laid for a long distance.
5) When the stored energy is dispatched to the power grid, other interface equipment is required to be added.
Disclosure of Invention
Accordingly, an object of the present invention is to provide a charging station system based on solid-state transformer, which effectively solves one or more of the above-mentioned disadvantages.
In order to achieve the above object, the present invention provides a charging station system based on a solid-state transformer, comprising:
the input side of the solid-state transformer is connected with a power distribution network, and the output side of the solid-state transformer is connected with at least one direct current bus;
the direct current bus is connected with at least one isolated charger and a non-isolated charger.
In an embodiment of the present invention, the non-isolated charger includes a non-isolated dc-dc converter, and the non-isolated dc-dc converter is connected to the dc bus.
In one embodiment of the present invention, the isolated charger includes an isolated dc-dc converter connected to the dc bus.
In an embodiment of the present invention, each of the dc buses is further connected with at least one of the following electric devices: photovoltaic system, energy storage battery, alternating current load and direct current load.
In an embodiment of the invention, the photovoltaic system is connected to the dc bus through a dc-dc converter; the energy storage battery is connected with the direct current bus through a direct current-direct current converter; the alternating current load is connected with the direct current bus through a direct current-alternating current converter; the direct current load is connected with the direct current bus through a direct current-direct current converter.
In an embodiment of the invention, the distribution network has a medium-voltage alternating-current voltage of 2.4-35 KV.
In an embodiment of the invention, each of the dc buses has a predetermined dc voltage.
In an embodiment of the invention, an output side of at least one of the solid-state transformers is connected to a plurality of the dc buses.
In an embodiment of the present invention, input sides of the plurality of solid-state transformers are connected to the power distribution network, and output sides of the plurality of solid-state transformers are connected to the same dc bus.
The charger system of the invention improves the efficiency of the whole system by adopting the SST-based framework, can keep higher efficiency under the condition from light load to full load, and is more suitable for the use scenes with more power consumption in no load or light load, such as charging stations. In addition, the SST is used as an intermediary (namely an energy router) for power exchange with the power distribution network, and the SST can directly communicate with the power grid and can perform four-quadrant operation, so that the flexibility of power grid energy scheduling is improved, and the expansion is more convenient. Moreover, the SST can control the power quality, and additional power quality management equipment such as a PQC (Power quality control) device is not required to be equipped.
By providing a constant direct current bus voltage for networking the power supply and utilization equipment, compared with an alternating current bus, when the same power is transmitted, the direct current line is low in manufacturing cost, a cable with the same insulation level can operate at higher direct current voltage, the power and energy loss of direct current transmission is low, and the direct current transmission has small interference on communication. Therefore, the invention adopts the direct current bus to build the network, can reduce the power loss caused by the thicker low-voltage alternating current cable, and reduce the material and construction cost.
The charging station system disclosed by the invention can be compatible with direct-current power utilization equipment such as new energy (such as PV), energy storage batteries (such as wind power), electric vehicle charging piles (isolated and non-isolated) and the like, namely, the power distribution, light, storage and charging are integrated, the robustness and flexibility of the system are enhanced, the requirement of the system on the electric quantity of a power grid is reduced due to the access of the new energy, the capability of the system for resisting load impact is increased due to the access of the energy storage equipment, and the charging station system can be used as an energy pool for power grid dispatching.
The charging station system can simultaneously meet the charging requirements of multiple vehicles by combining the non-isolated charger with the isolated charger, for example, combining the high-power high-efficiency non-isolated quick charger with a plurality of low-power isolated chargers, has less requirement on high-power quick charging vehicles and more requirement on low-power slow charging vehicles, and can effectively improve the utilization rate of the system by combining the two.
The above description will be described in detail by embodiments, and further explanation will be provided for the technical solution of the present invention.
Drawings
In order to make the aforementioned and other objects, features, and advantages of the invention, as well as others which will become apparent, reference is made to the following description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic diagram of a networking architecture based on a low-voltage AC bus in the prior art;
fig. 2 is a schematic diagram of a networking architecture of an SST-based charging station system according to a first preferred embodiment of the invention;
fig. 3 is a schematic diagram of a networking architecture of an SST-based charging station system according to a second preferred embodiment of the invention;
fig. 4 is a schematic diagram of a networking architecture of an SST-based charging station system according to a third preferred embodiment of the invention;
fig. 5 is a schematic diagram of a networking architecture of an SST-based charging station system according to a fourth preferred embodiment of the invention;
fig. 6 is a schematic diagram of a networking architecture of an SST-based charging station system according to a fifth preferred embodiment of the invention;
fig. 7 is a schematic diagram of a networking architecture of an SST-based charging station system according to a sixth preferred embodiment of the invention.
Detailed Description
For a better understanding and completeness of the description of the present invention, reference is made to the appended drawings and various embodiments described below in which like reference numerals represent the same or similar elements. In other instances, well-known elements and steps have not been described in detail in order to avoid unnecessarily obscuring the present invention. In addition, for the sake of simplicity, some conventional structures and elements are shown in the drawings in a simple schematic manner.
Referring to fig. 2, a networking architecture of an SST-based hybrid charging station system according to a first preferred embodiment of the invention is shown, which includes at least one SST, at least one non-isolated Charger (Charger), and at least one isolated Charger. Wherein, the input side of SST connects the distribution network, and the output side connects direct current bus, and this SST is as the intermediary with distribution network energy exchange. The medium-voltage alternating-current voltage (for example, 2.4-35 kV) of the power distribution network is converted by SST to obtain a direct-current bus, the direct-current bus can be connected with a high-power non-isolated direct-current charger (namely, a non-isolated charger) and a plurality of isolated direct-current chargers (namely, isolated chargers (for example, chargers 1-N), wherein the non-isolated direct-current charger comprises a non-isolated DC/DC converter connected with the direct-current bus, and the isolated direct-current charger comprises an isolated DC/DC converter connected with the direct-current bus. In addition, the non-isolated direct current charger can quickly charge a single vehicle, and the isolated direct current charger can slowly charge a plurality of vehicles in an isolated manner, so that the utilization rate of a quick charging system can be improved.
Although only one SST and one non-isolated dc charger are exemplarily shown in the embodiment of fig. 2, it is to be understood that the number of SSTs and one non-isolated dc charger may be plural, which should not be construed as a limitation to the present invention. For example, as shown in fig. 3, which shows a networking architecture of an SST-based charging station system of a second preferred embodiment of the present invention, it differs from the embodiment shown in fig. 2 in that: the DC bus is connected with N non-isolated DC chargers, such as chargers 1 to N connected to the DC bus through a non-isolated DC/DC converter in the figure.
In the invention, voltage levels of different direct current buses can be defined according to different use occasions, for example, a data center can be 400V, a charging station can be 1000V, and the like.
The SST-based hybrid charging station system of the present invention has the following advantages:
(1) the SST is used as an intermediary for power exchange with a power distribution network, the SST is a pure electric electronic device, the efficiency from light load to full load is high by selecting proper devices and topology, and the efficiency can be further improved by only performing DC/DC conversion on the later-stage electric device. In the prior art as shown in fig. 1, no-load loss of the medium-voltage transformer exists all the time, and the electric equipment at the later stage needs to be subjected to two stages of AC/DC rectification and DC/DC conversion, so that the overall efficiency is low. In contrast, the SST-based architecture is adopted, so that the efficiency of the whole system is improved, higher efficiency can be kept under the condition from light load to full load, and the SST-based architecture is more suitable for use scenes with more power consumption in no-load or light load, such as charging stations.
(2) The SST is used as an intermediary (energy router) for power exchange with a power distribution network, and the SST can directly communicate with a power grid and can perform four-quadrant operation, so that the flexibility of power grid energy scheduling is improved; moreover, the SST can control the power quality by itself, so that additional power quality management equipment such as a PQC is not required.
(3) Compared with an alternating current bus, when the same power is transmitted, the direct current bus is low in manufacturing cost, the cable with the same insulation level can run at higher direct current voltage, the power and energy loss of direct current transmission is low, and the interference of direct current transmission on communication is small. Therefore, the direct current bus networking is adopted, the power loss caused by the thicker low-voltage alternating current cable can be reduced, and the material and construction cost can be reduced.
(4) The invention combines a high-power non-isolated DC charger and a plurality of low-power isolated DC chargers, the non-isolated DC charger has higher efficiency compared with the isolated DC charger and is suitable for high-power quick charging, under the condition of certain SST power, the non-isolated DC charger can be used for short-time high-power quick charging, the isolated DC charger can be used for long-time low-power slow charging, and can simultaneously meet the charging of a plurality of vehicles, the high-power quick charging vehicle has less demand and the low-power slow charging vehicle has more demand, and the combination of the two can effectively improve the utilization rate of the system.
As shown in fig. 4, a networking architecture of an SST-based hybrid charging station system according to a third preferred embodiment of the present invention is shown, which is different from the embodiment shown in fig. 2 in that a photovoltaic system (PV) and an energy storage Battery (Battery) are further connected to the dc bus. The photovoltaic system is connected to the direct current bus through a DC/DC converter; the energy storage battery is connected to the direct current bus through a DC/DC converter. The networking architecture has the advantages that solar energy can be further converted into electric energy to be stored for charging the electric vehicle, consumption of electric energy of a power grid is reduced, and the power grid is supported when the power grid needs energy dispatching.
As shown in fig. 5, which illustrates a networking architecture of an SST-based hybrid charging station system according to a fourth preferred embodiment of the present invention, it is different from the embodiment shown in fig. 4 in that: the direct current bus is further connected with a direct current load and an alternating current load. Direct current loads such as an energy storage battery and a data center can be connected to the direct current bus through a DC/DC converter, and alternating current loads such as lighting, an air conditioner and electrodes can be connected to the direct current bus through a DC/AC converter. It is of course understood that a direct current power source, such as a wind power system (not shown), may also be connected to the direct current bus via a DC/DC converter. The networking architecture integrates power distribution, light, storage and charging, the robustness and flexibility of the system are enhanced, the requirement of the system on the electric quantity of a power grid is reduced due to the access of new energy (such as a photovoltaic system and a wind power system), the capability of the system for resisting load impact is increased due to the access of energy storage equipment (such as an energy storage battery), and the system can be used as an energy pool for power grid scheduling.
As shown in fig. 6, a networking architecture of an SST-based light collection, storage and charging integrated multi-dc bus hybrid charging station system according to a fifth preferred embodiment of the present invention is shown, in which, in particular, a medium voltage ac voltage (e.g., 2.4 to 35kV) of a power distribution network is converted by an SST to obtain at least two dc buses, e.g., including dc buses 1 to N, and power distribution and isolation among the dc buses are performed inside the SST according to different load requirements. In the embodiment shown in fig. 6, each dc bus is connected to a high-power non-isolated dc charger, N low-power isolated dc chargers, a photovoltaic system (PV), and an energy storage Battery (Battery). Of course, it is understood that in other embodiments, the electric devices connected to each dc bus may be configured according to different requirements, which are not intended to limit the present invention.
As shown in fig. 7, a networking architecture of a hybrid charging station system with integrated light collection and storage based on multiple SSTs according to a sixth preferred embodiment of the present invention is shown, and particularly, at least two SSTs are included as intermediaries for energy exchange with a power distribution network, for example, SST 1 to SST N are included, and a medium voltage alternating voltage (for example, 2.4 to 35kV) of the power distribution network is converted by the SST to obtain a same dc bus, and power distribution and isolation between the dc buses are performed between the SSTs according to different load requirements. Moreover, different quantities of SSTs can be configured according to different power levels of stations for networking, and different quantities of SSTs can be flexibly configured to operate according to different load power requirements, so that the system has more flexibility. In the embodiment shown in fig. 7, a high-power non-isolated dc charger, N low-power isolated dc chargers, a photovoltaic system (PV), and an energy storage Battery (Battery) are connected to the dc bus.
Fig. 2 to 7 show networking architectures of different embodiments of the SST-based charging station system of the present invention, it being understood that the form of the networking architecture may be configured differently according to different requirements or different application scenarios, i.e. the form is various, which is only a few examples, but does not exclude other possibilities.
In summary, the present invention provides a charging station system based on a solid-state transformer, which includes: the system comprises at least one Solid State Transformer (SST), wherein the input side of the SST is connected with a power distribution network, and the output side of the SST is connected with at least one direct current bus; the direct current bus is connected with at least one isolated charger and a non-isolated charger.
In an embodiment of the present invention, the non-isolated charger includes a non-isolated dc-dc converter, and the non-isolated dc-dc converter is connected to the dc bus.
In one embodiment of the present invention, the isolated charger includes an isolated dc-dc converter, and the isolated dc-dc converter is connected to the dc bus.
In an embodiment of the present invention, each of the dc buses is further connected with at least one of the following electric devices: photovoltaic system, energy storage battery, alternating current load and direct current load.
In an embodiment of the present invention, the photovoltaic system is connected to the dc bus through a dc-dc converter; the energy storage battery is connected with the direct current bus through a direct current-direct current converter; the alternating current load is connected with the direct current bus through a direct current-alternating current converter; the direct current load is connected with the direct current bus through a direct current-direct current converter.
In an embodiment of the invention, the distribution network has a medium-voltage alternating-current voltage of 2.4-35 KV.
In an embodiment of the invention, each of the dc buses has a predetermined dc voltage.
In an embodiment of the invention, a plurality of dc buses are connected to an output side of at least one of the solid-state transformers.
In an embodiment of the present invention, input sides of the plurality of solid-state transformers are connected to the power distribution network, and output sides of the plurality of solid-state transformers are connected to the same dc bus.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.
Claims (9)
1. A solid state transformer based charging station system, comprising:
the input side of the solid-state transformer is connected with a power distribution network, and the output side of the solid-state transformer is connected with at least one direct current bus;
the direct current bus is connected with at least one isolated charger and a non-isolated charger.
2. The solid state transformer based charging station system of claim 1, wherein the non-isolated charger comprises a non-isolated dc-dc converter, the non-isolated dc-dc converter connected to the dc bus.
3. The solid state transformer based charging station system of claim 1, wherein said isolated charger comprises an isolated dc-dc converter, said isolated dc-dc converter connected to said dc bus.
4. The solid state transformer based charging station system of claim 1, wherein each of the dc buses is further connected to at least one of the following electrical devices: photovoltaic system, energy storage battery, alternating current load and direct current load.
5. The solid state transformer based charging station system of claim 4, wherein the photovoltaic system is connected to the dc bus via a dc-dc converter; the energy storage battery is connected with the direct current bus through a direct current-direct current converter; the alternating current load is connected with the direct current bus through a direct current-alternating current converter; the direct current load is connected with the direct current bus through a direct current-direct current converter.
6. The solid state transformer based charging station system of claim 1, wherein the power distribution grid has a medium voltage ac voltage of 2.4-35 KV.
7. The solid state transformer based charging station system of claim 1, wherein each of the dc busses has a predetermined dc voltage.
8. The solid state transformer based charging station system according to any one of claims 1 to 7, wherein a plurality of said DC buses are connected to an output side of at least one of said solid state transformers.
9. The solid state transformer based charging station system according to any one of claims 1 to 7, wherein a plurality of said solid state transformers are connected to said distribution network on the input side and to the same said DC bus on the output side.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910544884.XA CN112117776A (en) | 2019-06-21 | 2019-06-21 | Charging station system based on solid-state transformer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910544884.XA CN112117776A (en) | 2019-06-21 | 2019-06-21 | Charging station system based on solid-state transformer |
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| CN112117776A true CN112117776A (en) | 2020-12-22 |
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