Distributed flexible interconnection and energy storage integrated charging pile

Abstract

The present invention discloses a distributed flexible interconnection and energy storage integrated charging pile in the field of charging pile technology, including: an AC / DC power conversion module, whose AC side port is connected to the distribution transformer of the substation through an AC electrical interface, and whose DC side port is connected to the extended DC bus; an isolated bidirectional DC power conversion module, whose first DC side port is connected to the extended DC bus, and whose second DC side port is connected to the variable voltage DC bus; the extended DC bus is connected to the substation DC bus through a DC bus interface; a non-isolated unidirectional DC power conversion module, whose first DC side port is connected to the variable voltage DC bus, and whose second DC side port is connected to the charging gun; an energy storage module, connected to the variable voltage DC bus. The present invention can reduce the equipment footprint, improve system efficiency, and reduce system construction and operation and maintenance costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of charging piles, and in particular relates to a distributed flexible interconnection and energy storage integrated charging pile. Background Art

[0002] At present, distribution station areas have business needs such as flexible interconnection, energy storage, photovoltaic access and DC charging of electric vehicles. Flexible interconnection devices, energy storage devices, photovoltaic systems and DC charging functional devices for electric vehicles are installed respectively to meet the above business needs. The existing technology has the problems of large equipment footprint, the need to install additional collaborative control systems, low overall system efficiency and high system equipment construction and operation and maintenance costs. Summary of the invention

[0003] In order to solve the deficiencies in the prior art, the present invention provides a distributed flexible interconnection and energy storage integrated charging pile, which can reduce the equipment footprint, improve system efficiency, and reduce system construction and operation and maintenance costs.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a distributed flexible interconnection and energy storage integrated charging pile, including: an AC / DC power conversion module, whose AC side port is connected to the substation distribution transformer through an AC electrical interface, and whose DC side port is connected to the extended DC bus; an isolated bidirectional DC power conversion module, whose first DC side port is connected to the extended DC bus, and whose second DC side port is connected to the variable voltage DC bus; the extended DC bus is connected to the substation DC bus through a DC bus interface; a non-isolated unidirectional DC power conversion module, whose first DC side port is connected to the variable voltage DC bus, and whose second DC side port is connected to the charging gun; an energy storage module, connected to the variable voltage DC bus.

[0005] Furthermore, there are two AC / DC power conversion modules, and the AC side ports of the two AC / DC power conversion modules are connected to different distribution transformers in different substations through an AC electrical interface respectively.

[0006] Furthermore, the charging pile satisfies: PT<=min(PA, PB); PC<=(PA+PB); PD<=PC+ PED (SOC); wherein PT represents the maximum flexible interconnection power, PA represents the rated power of one of the AC / DC power conversion modules, PB represents the rated power of the other AC / DC power conversion module, PC represents the rated power of the isolated bidirectional DC power conversion module, PD represents the rated power of the non-isolated unidirectional DC power conversion module, and PED (SOC) represents the maximum discharge power of the energy storage module.

[0007] Furthermore, the AC / DC power conversion modules can constitute a flexible interconnection device for substations to achieve power transfer between substations.

[0008] Furthermore, the AC / DC power conversion module, the isolated bidirectional DC power conversion module, and the energy storage module constitute a substation energy storage system, which stores the electric energy from the grid and / or the electric energy produced by the photovoltaic system connected to the extended DC bus at the first DC side port, and releases it to the grid and / or the charging port.

[0009] Furthermore, the AC / DC power conversion module, the isolated bidirectional DC power conversion module, and the non-isolated unidirectional DC power conversion module constitute an electric vehicle charging system, which supplies the electric vehicle with electric energy from the power grid and / or electric energy produced by the photovoltaic system connected to the extended DC bus at the first DC side port and / or electric energy released by the energy storage module.

[0010] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses an AC / DC power conversion module substation distribution transformer and an extended DC bus, connects the extended DC bus with the variable voltage DC bus through an isolated bidirectional DC power conversion module, connects the extended DC bus to the substation DC bus through a DC bus interface, connects the variable voltage DC bus with the charging gun through a non-isolated unidirectional DC power conversion module, and connects the variable voltage DC bus through an energy storage module. It integrates the functions of substation flexible interconnection, substation energy storage, substation photovoltaic access and DC charging of electric vehicles, and uses a high-power DC charging pile as a carrier to construct an integrated modular charging pile with flexible interconnection, PEG energy storage, and distributed photovoltaic flexible access and absorption capabilities. Based on the system operation characteristics, by reusing power supply equipment, the equipment footprint is reduced, the system efficiency is improved, and the system construction and operation and maintenance costs are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the electrical topology of a distributed flexible interconnection and energy storage integrated charging pile provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0012] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0013] like Figure 1 As shown, a distributed flexible interconnection and energy storage integrated charging pile includes: a first AC electrical interface 101 and a second AC electrical interface 102, which are used to connect to distribution transformers under two different lines.

[0014] The DC bus interface 103 is used to connect to the output of the photovoltaic converter.

[0015] The charging gun 104 is used to connect to the electric vehicle coupler and charge the electric vehicle.

[0016] The first AC / DC power conversion module 201 and the second AC / DC power conversion module 202 are used to realize power conversion and power transmission between the AC station and the DC bus.

[0017] The extended DC bus 302 is used to connect the first AC / DC power conversion module 201, the second AC / DC power conversion module 202 and the DC bus interface 103 in the device.

[0018] The isolated bidirectional DC power conversion module 203 is used to realize power conversion and power transmission between the extended DC bus 302 and the variable voltage DC bus 301 .

[0019] The variable voltage DC bus 301 is used to connect the isolated bidirectional DC power conversion module 203, the energy storage module 205 and the non-isolated unidirectional DC power conversion module 204 in the device.

[0020] The energy storage module 205 is used to store the photovoltaic power generated by the DC bus interface 103 and the power connected to the AC distribution network from the first AC electrical interface 101 and the second AC electrical interface 102, and provide power to the electric vehicle through the non-isolated unidirectional DC power conversion module 204 and the charging gun 104, and feed power to the AC distribution network through the isolated bidirectional DC power conversion module 203, the first AC electrical interface 101, and the second AC electrical interface 102.

[0021] The non-isolated unidirectional DC power conversion module 204 is used to charge the electric vehicle via the charging gun 104 .

[0022] The first AC electrical interface 101 is connected to the AC side port of the first AC / DC power conversion module 201, the second AC electrical interface 102 is connected to the AC side port of the second AC / DC power conversion module 202, the DC side port of the first AC / DC power conversion module 201 is connected to the extended DC bus 302, the DC side port of the second AC / DC power conversion module 202 is connected to the extended DC bus 302, the DC bus interface 103 is connected to the extended DC bus 302, the first DC side port of the isolated bidirectional DC power conversion module 203 is connected to the extended DC bus 302, the second DC side port of the isolated bidirectional DC power conversion module 203 is connected to the variable voltage DC bus 301, the variable voltage DC bus 301 is connected to the first DC side interface of the non-isolated unidirectional DC power conversion module 204, the variable voltage DC bus 301 is connected to the energy storage module 205, and the second DC side interface of the non-isolated unidirectional DC power conversion module 204 is connected to the charging gun 104.

[0023] The first AC electrical interface 101 and the second AC electrical interface 102 are respectively connected to the feeders of the distribution transformer A and the distribution transformer B that need to be flexibly interconnected in the substation area. The DC bus interface 103 is connected to the DC bus of the substation area, and is usually connected to photovoltaic, energy storage, DC power supply charging piles, etc.

[0024] The maximum flexible interconnection power that can be provided by this embodiment is PT, the rated power of the first AC / DC power conversion module 201 is PA, the rated power of the second AC / DC power conversion module 202 is PB, the rated power of the isolated bidirectional DC power conversion module 203 is PC, the rated power of the non-isolated unidirectional DC power conversion module 204 is PD, the maximum charging power of the energy storage module 205 is PEC, and the maximum discharge power of the energy storage module 205 is PED. PEC and PED are functions of the SOC of the energy storage module 205.

[0025] This embodiment needs to meet the following requirements:

[0026] PT is not higher than the minimum value of PA and PB, that is, PT<=min(PA, PB);

[0027] PC power is not greater than the sum of PA and PB powers, that is, PC <= (PA + PB);

[0028] PD is not higher than the sum of the maximum values ​​of PC and PED, that is, PD<=PC+PED (SOC).

[0029] In this embodiment, the flexible interconnection power is Pt, the input power of the DC bus interface 103 is Pf, the operating power of the first AC / DC power conversion module 201 is Pa, the operating power of the second AC / DC power conversion module 202 is Pb, the operating power of the isolated bidirectional DC power conversion module 203 is Pc, the operating power of the non-isolated unidirectional DC power conversion module 204 is Pd, the charging power of the energy storage module 205 is Pec, and the discharging power is Ped;

[0030] Working scene 1:

[0031] The charging gun 104 is idle, Pt>0, Pf>0, and the SOC of the energy storage module 205 is <95%;

[0032] Pb=-Pt, Pc=min (PC, PA-Pt+Pf, PEC (SOC)), Pa=Pt+Pc-Pf, Pec=Pc.

[0033] Working scene 2:

[0034] The charging gun 104 is idle, Pt<0, Pf>0, and the SOC of the energy storage module 205 is <95%;

[0035] Pa=Pt, Pc=min (PC, PB+Pt+Pf, PEC (SOC)), Pb=-Pt+Pc-Pf, Pec=Pc.

[0036] Working scene three:

[0037] The charging gun 104 is charged, Pt>0, Pf>0, Pd<min(PC, PA-Pt+pf);

[0038] Pa=Pt+Pd, Pb=-Pt, Pc=Pd, Pec=0.

[0039] Working scene 4:

[0040] The charging gun 104 is charged, Pt<0, Pf>0, Pd<min(PC, PA-Pt+pf);

[0041] Pa=Pt, Pb=-Pt+Pd, Pc=Pd, Pec=0.

[0042] Working scene five:

[0043] The charging gun 104 is charging, Pt>0, Pf>0, Pd>min(PC,PA-Pt+pf), and the SOC of the energy storage module 205 is>20%;

[0044] Pa=Pt, Pb=PB, Pc= min (PC, PA-Pt+pf), Ped=Pd-Pc.

[0045] Working scene six:

[0046] The charging gun 104 is charging, Pt<0, Pf>0, Pd>min(PC,PA-Pt+pf), and the SOC of the energy storage module 205 is>20%;

[0047] Pa=PA, Pb=-Pt, Pc= min(PC, PA-Pt+pf), Ped=Pd-Pc.

[0048] In this embodiment, the substation distribution transformer and the extended DC bus are connected through the first AC / DC power conversion module 201 and the second AC / DC power conversion module 202, and the extended DC bus 302 is connected to the variable voltage DC bus 301 through the isolated bidirectional DC power conversion module 203. The extended DC bus 302 is connected to the substation DC bus through the DC bus interface 103, and the variable voltage DC bus 301 is connected to the charging gun 104 through the non-isolated unidirectional DC power conversion module 204, and is connected to the variable voltage DC bus 301 through the energy storage module 205. The functions of flexible interconnection of the substation composed of the first AC / DC power conversion module 201 and the second AC / DC power conversion module 202, the substation energy storage composed of the first AC / DC power conversion module 201, the second AC / DC power conversion module 202, the isolated bidirectional DC power conversion module 203, and the energy storage module 205, the substation photovoltaic access composed of the first AC / DC power conversion module 201, the second AC / DC power conversion module 202, and the DC bus interface 103, and the DC charging of the electric vehicle composed of the first AC / DC power conversion module 201, the second AC / DC power conversion module 202, the isolated bidirectional DC power conversion module 203, the non-isolated unidirectional DC power conversion module 204, and the charging gun 104 are integrated together, and a high-power DC charging pile is used as a carrier to construct an integrated modular charging pile with flexible interconnection, PEG energy storage, and distributed photovoltaic flexible access and absorption capabilities. Based on the system operation characteristics, by reusing power supply equipment, the equipment footprint is reduced, the system efficiency is improved, and the system construction and operation and maintenance costs are reduced.

[0049] This embodiment also provides the design parameters of a 120 kW integrated charging pile as follows:

[0050] The first AC / DC power conversion module 201 and the second AC / DC power conversion module 202 both use a 30kW T-type three-level AC / DC module, with an AC side rated voltage of 380Vac, a DC side rated voltage of 750Vdc, and an average efficiency of 98% above 50% load, PA=30kW, PB=30kW;

[0051] The isolated bidirectional DC power conversion module 203 uses three 20kW DAB topology modules connected in parallel for current sharing. The rated voltage of the first DC side port is 750Vdc, and the voltage variation range of the second DC side port is 600Vdc-900Vdc. The average efficiency of the module is 98% when the load is above 50%, and PC=60kW.

[0052] The DC bus interface 103 is connected to 750Vdc grid-connected photovoltaic 10kW;

[0053] Energy storage module 205 uses a lithium iron phosphate battery module with a 2C charge and discharge rate, a capacity of 30.72kWh, and the module uses 240 40Ah cells connected in series;

[0054] The non-isolated unidirectional DC power conversion module 204 uses a 120kW unidirectional Buck topology module, the first DC side voltage operating range is 600V-900V, and the second DC side operating voltage is 200V-600V.

[0055] Working scene 1:

[0056] Pt=20kW, Pd=0kW, Pf=10kW, SOC of 205=30%;

[0057] Pa=30kW, Pb=-20kW, Pc=30kW, Pec=30kW.

[0058] Working scene 2:

[0059] Pt=-20kW, Pd=0kW, Pf=10kW, SOC of 205=95%;

[0060] Pa=-20kW, Pb=10kW, Pc=0kW, Pec=0kW.

[0061] Working scene three:

[0062] Pt=10kW, Pd=25kW, Pf=10kW;

[0063] Pa=25kW, Pb=10kW, Pc=25kW, Pec=0kW.

[0064] Working scene 4:

[0065] Pt=20kW, Pd=25kW, Pf=0kW, SOC of 205=95%;

[0066] Pa=30kW, Pb=20kW, Pc=10kW, Ped=15kW.

[0067] In this embodiment, two AC / DC power conversion modules connected to distribution transformers in different substations can constitute a flexible interconnection device in the substation area to realize power transfer between substations. Two AC / DC power conversion modules, isolated bidirectional DC power conversion modules, and energy storage modules connected to distribution transformers in different substations constitute a substation energy storage system, which can store the electric energy from the power grid and / or the electric energy produced by the photovoltaic system connected to the first DC side port connected to the extended DC bus, and release it to the power grid and / or the charging port. Two AC / DC power conversion modules, isolated bidirectional DC power conversion modules, and non-isolated unidirectional DC power conversion modules connected to distribution transformers in different substations can constitute an electric vehicle charging system, which supplies the electric energy from the power grid and / or the electric energy produced by the photovoltaic system connected to the first DC side port connected to the extended DC bus, and / or the electric energy released by the energy storage module to the electric vehicle.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Distributed flexible interconnection and energy storage integrated charging pile, characterized by: include: An AC / DC power conversion module, wherein an AC side port thereof is connected to a substation distribution transformer via an AC electrical interface, and a DC side port thereof is connected to an extended DC bus (302); wherein the AC / DC power conversion module comprises a first AC / DC power conversion module (201) and a second AC / DC power conversion module (202); the AC electrical interface comprises a first AC electrical interface (101) and a second AC electrical interface (102); the first AC / DC power conversion module (201) and the second AC / DC power conversion module (202) are connected to different substation distribution transformers via the first AC electrical interface (101) and the second AC electrical interface (102), respectively, to achieve power conversion and power transmission between the AC substation and the DC bus; An isolated bidirectional DC power conversion module (203), wherein a first DC side port thereof is connected to an extended DC bus (302), and a second DC side port thereof is connected to a variable voltage DC bus (301); the isolated bidirectional DC power conversion module (203) is used to realize electric energy conversion and power transmission between the extended DC bus (302) and the variable voltage DC bus (301); The extended DC bus (302) is connected to the DC bus of the substation via a DC bus interface (103), and the DC bus interface (103) is used to be connected to the output of the photovoltaic converter; A non-isolated unidirectional DC power conversion module (204), wherein a first DC side port thereof is connected to a variable voltage DC bus (301), and a second DC side port thereof is connected to a charging gun (104); An energy storage module (205) is connected to the variable voltage DC bus (301) and is used to store photovoltaic power generated by the DC bus interface (103) and power generated by the AC distribution network connected to the first AC electrical interface (101) and the second AC electrical interface (102), and to provide power to the electric vehicle through the non-isolated unidirectional DC power conversion module (204) and the charging gun (104), and to feed power to the AC distribution network through the isolated bidirectional DC power conversion module (203), the first AC electrical interface (101), and the second AC electrical interface (102); A first AC / DC power conversion module (201) and a second AC / DC power conversion module (202) connected to distribution transformers in different substations form a substation flexible interconnection device to achieve power transfer between substations; A first AC / DC power conversion module (201), a second AC / DC power conversion module (202), an isolated bidirectional DC power conversion module (203), and an energy storage module (205) connected to distribution transformers in different substations form a substation energy storage system, which stores electric energy from a power grid and / or electric energy produced by a photovoltaic system connected to an extended DC bus (302) via a DC bus interface (103), and releases the electric energy to the power grid and / or a charging port; A first AC / DC power conversion module (201), a second AC / DC power conversion module (202), an isolated bidirectional DC power conversion module (203), and a non-isolated unidirectional DC power conversion module (204) connected to distribution transformers in different substations constitute an electric vehicle charging system, which supplies electric energy from a power grid and / or electric energy produced by a photovoltaic system connected to an extended DC bus (302) and / or electric energy released by an energy storage module (205) to the electric vehicle.

2. The distributed flexible interconnection and energy storage integrated charging pile according to claim 1 is characterized in that: The charging pile meets the following requirements: PT<=min(PA,PB); PC<=(PA+PB); PD<=PC+PED(SOC); Among them, PT represents the maximum flexible interconnection power, PA represents the rated power of one of the AC / DC power conversion modules, PB represents the rated power of the other AC / DC power conversion module, PC represents the rated power of the isolated bidirectional DC power conversion module, PD represents the rated power of the non-isolated unidirectional DC power conversion module, and PED (SOC) represents the maximum discharge power of the energy storage module.

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