Charging method and light storage charging system

Abstract

The application provides a charging method and a light storage charging system in the technical field of electric vehicles, wherein an alternating current photovoltaic power generation system, an energy storage converter and a battery energy storage system are arranged, light energy is used to charge the electric vehicle and the battery energy storage system, the energy storage converter is used to convert the electric energy in the battery energy storage system to charge the electric vehicle, and the battery energy storage system is intelligently charged through a peak load shifting strategy created by an energy management system, so that the maximum output power of an alternating current power distribution cabinet is limited, the output power is finally improved under the premise that the power distribution network pressure is not increased, the power grid does not need to be expanded, the line does not need to be transformed, the number of charging piles can be increased, and more electric vehicles can be charged.

Description

[0001] This case is a divisional application based on the invention patent with application date of January 21, 2021, application number 202110080940.6, and name “A Photovoltaic Storage and Charging System and Operation Method” as the parent case. Technical Field

[0002] The present invention relates to the technical field of electric vehicles, and in particular to a charging method and a solar storage and charging system. Background Art

[0003] With the rapid increase in the number of electric vehicles, the demand for electric vehicle charging is also growing rapidly. The number of charging piles in parking lots, shopping malls, charging stations and residential communities is increasingly unable to meet the charging needs of electric vehicles.

[0004] Further increasing the number of charging piles at the original site will increase the pressure on the power distribution network, and the existing distribution lines will need to be modified. In areas with dense populations and a large demand for charging, the power distribution capacity of the power grid is often limited and difficult to modify. Simply adding charging piles will cause local power grid instability. In some old communities, the power distribution capacity of the power grid has even reached its upper limit, making it impossible to continue increasing the number of charging piles.

[0005] Therefore, how to provide a charging method and a solar-storage-charging system to increase output power without increasing the pressure on the power distribution network has become an urgent problem to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a charging method and a solar storage and charging system to increase the output power without increasing the pressure on the power distribution network.

[0007] In a first aspect, the present invention provides a charging method, comprising:

[0008] Step 1: Create a peak load shifting strategy and set a low power threshold.

[0009] Step 2: Calculate the required charging power of the electric vehicle based on the charging parameters of the electric vehicle;

[0010] Step 3: Determine whether the power grid is online through the AC power distribution cabinet. If so, proceed to step 4; if not, disconnect the AC power distribution cabinet from the power grid, and control the AC photovoltaic power generation system and the battery energy storage system to charge the electric vehicle based on the charging demand power.

[0011] Step 4: Determine whether the power level of the battery energy storage system is lower than the low power threshold. If so, proceed to step 5; otherwise, proceed to step 6.

[0012] Step 5: Determine whether the charging demand power is greater than the output power of the AC photovoltaic power generation system. If so, use the AC photovoltaic power generation system to charge the electric vehicle, and then use the AC power distribution cabinet and the AC photovoltaic power generation system to charge the electric vehicle and the battery energy storage system based on the peak shaving and valley filling strategy and the maximum power. If not, use the AC photovoltaic power generation system to charge the electric vehicle and the battery energy storage system.

[0013] Step 6: Determine whether the required charging power is greater than the sum of the output powers of the AC photovoltaic power generation system and the battery energy storage system. If so, use the AC power distribution cabinet, the AC photovoltaic power generation system, and the battery energy storage system to charge the electric vehicle in combination with the maximum power; if not, use the AC photovoltaic power generation system and the battery energy storage system to charge the electric vehicle.

[0014] The maximum power is the sum of the rated powers of all old AC charging piles.

[0015] In a second aspect, the present invention provides a solar storage and charging system, comprising:

[0016] An AC distribution cabinet;

[0017] At least one old AC charging pile connected to the AC power distribution cabinet;

[0018] A charging pile controller connected to the AC power distribution cabinet and the old AC charging pile;

[0019] At least one new AC charging pile connected to the charging pile controller;

[0020] an AC photovoltaic power generation system connected to the old AC charging pile and the charging pile controller;

[0021] an energy storage converter connected to the AC power distribution cabinet, the old AC charging pile, the charging pile controller, and the AC photovoltaic power generation system;

[0022] a battery energy storage system connected to the energy storage converter;

[0023] an energy management system connected to the AC power distribution cabinet, the charging pile controller, the old AC charging pile, the new AC charging pile, the AC photovoltaic power generation system, the energy storage converter, and the battery energy storage system;

[0024] The energy management system implements each step of the above-mentioned charging method.

[0025] The advantages of the present invention are:

[0026] By setting up an AC photovoltaic power generation system, an energy storage inverter and a battery energy storage system, it is possible to use light energy to charge electric vehicles and battery energy storage systems. The energy storage inverter can invert the electric energy in the battery energy storage system to charge electric vehicles. The peak-shaving and valley-filling strategy created by the energy management system can be used to intelligently charge the battery energy storage system, limiting the maximum power output of the AC distribution cabinet. Ultimately, the output power can be increased without increasing the pressure on the power distribution network. That is, there is no need to expand the capacity of the power grid or modify the lines, and the number of charging piles can be increased, thereby charging more electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Figure 1 This is a circuit principle block diagram of a light storage and charging system of the present invention.

[0029] Figure 2 It is a circuit principle block diagram of the battery energy storage system of the present invention.

[0030] Figure 3 This is a circuit principle block diagram of the use status of a light storage and charging system of the present invention.

[0031] Figure 4 It is a schematic diagram of the power output of a solar storage and charging system of the present invention.

[0032] Figure 5 It is a flow chart of an operating method of a solar storage and charging system of the present invention.

[0033] Marking Description:

[0034] 100. A photovoltaic storage and charging system: 1. AC power distribution cabinet, 2. Old AC charging pile, 3. Charging pile controller, 4. New AC charging pile, 5. AC photovoltaic power generation system, 6. Energy storage converter, 7. Battery energy storage system, 8. Energy management system, 9. UPS, 10. Load, 11. Server, 12. Electric vehicle, 51. Photovoltaic controller, 52. Photovoltaic module, 71. BMS, 72. Lithium iron phosphate battery. DETAILED DESCRIPTION

[0035] The general idea of the technical solutions in the embodiments of the present application is as follows: an alternating current photovoltaic power generation system 5 is arranged to convert light energy into electric energy to charge an electric vehicle 12; an energy storage converter 6 and a battery energy storage system 7 are arranged, the battery energy storage system 7 is charged when the light storage charging system 100 is idle, and the electric energy in the battery energy storage system 7 is inverted to charge the electric vehicle 12 through the energy storage converter 6 when the electric vehicle 12 has a charging demand; a peak load shifting strategy is arranged to balance the peak and valley power of the power grid; the highest power output by the alternating current power distribution cabinet 1 is limited to avoid increasing the pressure of the power distribution network, so as to improve the output power without increasing the pressure of the power distribution network.

[0036] Please refer to Figures 1 to 5 The preferred embodiment of the light storage charging system 100 of the present application is shown in the figure, the solid line represents a high-voltage line, and the dashed line represents a communication line. The preferred embodiment of the light storage charging system 100 of the present application comprises:

[0037] An alternating current power distribution cabinet 1 is arranged to access the power grid and distribute the electric energy of the power grid to the old alternating current charging pile 2, the new alternating current charging pile 4, the charging pile controller 3, the load 10, the battery energy storage system 7 and the like;

[0038] At least one old alternating current charging pile 2 is connected with the alternating current power distribution cabinet 1 and has the functions of electric energy metering and insulation detection;

[0039] A charging pile controller 3 is connected with the alternating current power distribution cabinet 1 and the old alternating current charging pile 2 and is used to control the output power of the new alternating current charging pile 4, communicate with the electric vehicle 12 through the new alternating current charging pile 4, reduce the output power of the new alternating current charging pile 4 when the electric quantity of the battery energy storage system 7 is insufficient and the alternating current photovoltaic power generation system 5 has no energy, and preferentially ensure the power output of the old alternating current charging pile 2;

[0040] At least one new alternating current charging pile 4 is connected with the charging pile controller 3 and has the functions of electric energy metering and insulation detection;

[0041] An alternating current photovoltaic power generation system 5 is connected with the old alternating current charging pile 2 and the charging pile controller 3;

[0042] An energy storage converter (PCS) 6 is connected with the alternating current power distribution cabinet 1, the old alternating current charging pile 2, the charging pile controller 3 and the alternating current photovoltaic power generation system 5; the energy storage converter 6 is used to control the charging and discharging of the battery energy storage system 7, accept the energy allocation and control protection of the energy management system 8;

[0043] A battery energy storage system 7 is connected with the energy storage converter 6 and is used for the buffering action in the energy allocation process, so as to achieve the purposes of peak load shifting, capacity expansion and relieving the pressure of the power distribution capacity of the power grid;

[0044] An energy management system (EMS) 8 is respectively connected to the AC distribution cabinet 1, the charging pile controller 3, the old AC charging pile 2, the new AC charging pile 4, the AC photovoltaic power generation system 5, the energy storage converter 6 and the battery energy storage system 7; the energy management system 8 is used to control the operation of the photovoltaic storage and charging system 100 and upload the charging data of the electric vehicle 12 to the server 11.

[0045] The AC photovoltaic power generation system 5 includes:

[0046] A photovoltaic controller 51 is connected to the old AC charging pile 2, the charging pile controller 3 and the energy management system 8 respectively;

[0047] A set of photovoltaic panels 52 is connected to the photovoltaic controller 51. The photovoltaic controller 51 has an MPPT power tracking function to achieve high-efficiency DC / AC conversion. The DC energy output by the photovoltaic panels 52 is converted to a voltage that matches the AC bus, and the green energy is stored in the battery energy storage system 7 or directly used by the load 10.

[0048] The battery energy storage system 7 includes:

[0049] a BMS 71 connected to the energy storage converter 6 and the energy management system 8 respectively;

[0050] A plurality of lithium iron phosphate batteries 72 are connected to the BMS 71 and the energy storage converter 6 respectively; the lithium iron phosphate batteries 72 are connected in series and parallel, and the BMS 71 is used to collect data and perform control protection on the lithium iron phosphate batteries 72 .

[0051] The AC distribution cabinet 1 is provided with an AC bidirectional meter (not shown).

[0052] Also includes:

[0053] A UPS (Uninterruptible Power Supply) 9 is connected to the energy management system 8 to ensure uninterrupted operation of the energy management system 8 in the event of a power outage.

[0054] A preferred embodiment of a method for operating a solar-storage-charge system according to the present invention includes the following steps:

[0055] Step S10: The energy management system limits the maximum power output by the AC power distribution cabinet;

[0056] Step S20: Each electric vehicle establishes a connection with the old AC charging pile or the new AC charging pile, locks the electronic lock to prevent the charging head from falling off, and enters the self-test phase. The low-voltage auxiliary power supply circuit is turned on to power the control device of the electric vehicle, and an insulation test is performed. After the insulation test is completed, the electric energy is fed into the discharge circuit to discharge energy.

[0057] Step S30: The old AC charging pile or the new AC charging pile interacts with the electric vehicle in real time to obtain charging parameters of the electric vehicle and sends them to the energy management system;

[0058] Step S40: The energy management system creates a peak-shaving and valley-filling strategy, and controls the AC distribution cabinet, AC photovoltaic power generation system, or battery energy storage system to charge the electric vehicle based on the peak-shaving and valley-filling strategy, charging parameters, and maximum power.

[0059] Step S50: After the energy management system determines based on the charging parameters that the electric vehicle is fully charged, the AC photovoltaic power generation system has no energy output, and the battery energy storage system reaches a preset SOC, it stops the power output of the AC distribution cabinet, the AC photovoltaic power generation system, or the battery energy storage system.

[0060] During specific implementation, the energy management system can record the power usage in each time period, and then optimize the power distribution and energy management based on the power usage, further improving the rationality of energy utilization.

[0061] The step S10 is specifically as follows:

[0062] The energy management system limits the maximum power output of the AC distribution cabinet to the sum of the rated power of all old AC charging piles.

[0063] In step S30, the charging parameters include at least the maximum allowable total charging voltage of the power battery system, the maximum allowable charging current of the power battery system, the maximum allowable charging voltage of the single cell, the maximum allowable temperature of the single cell, the current voltage of the single cell, the current voltage of the power battery system, the real-time SOC of the single cell, and the real-time SOC of the power battery system.

[0064] The step S40 specifically includes:

[0065] Step S41: The energy management system creates a peak-shaving and valley-filling strategy and sets a low power threshold;

[0066] Step S42: The energy management system calculates the required charging power of the electric vehicle based on the charging parameters;

[0067] Step S43: The energy management system determines whether the power grid is online through the AC power distribution cabinet. If so, the process proceeds to step S44; if not, the AC power distribution cabinet is disconnected from the power grid, and the AC photovoltaic power generation system and the battery energy storage system are controlled based on the charging demand power to charge the electric vehicle, and the process proceeds to step S50.

[0068] Step S44: The energy management system determines whether the power level of the battery energy storage system is lower than the low power threshold. If so, the process proceeds to step S45; if not, the process proceeds to step S46.

[0069] Step S45: The energy management system determines whether the charging demand power is greater than the output power of the AC photovoltaic power generation system. If so, the AC photovoltaic power generation system is preferentially used to charge the electric vehicle. Then, based on the peak shaving and valley filling strategy and the maximum power, the AC power distribution cabinet and the AC photovoltaic power generation system are used to charge the electric vehicle and the battery energy storage system, and the process proceeds to step S50. If not, the AC photovoltaic power generation system is used to charge the electric vehicle and the battery energy storage system, and the process proceeds to step S50.

[0070] Step S46: The energy management system determines whether the required charging power is greater than the sum of the output powers of the AC photovoltaic power generation system and the battery energy storage system. If so, the AC power distribution cabinet, the AC photovoltaic power generation system, and the battery energy storage system are used to charge the electric vehicle in combination with the maximum power, and the process proceeds to step S50. If not, the AC photovoltaic power generation system and the battery energy storage system are used to charge the electric vehicle, and the process proceeds to step S50.

[0071] In step S40, the peak shaving and valley filling strategy is specifically as follows:

[0072] Set the time periods corresponding to normal, off-peak and peak periods, and determine whether the current time is in normal, off-peak or peak period.

[0073] During normal hours, power is drawn from the grid through the AC distribution cabinet to charge electric vehicles, and the battery energy storage system is not charged through the AC distribution cabinet.

[0074] During off-peak hours, power is drawn from the grid via the AC distribution cabinet to charge electric vehicles and battery energy storage systems.

[0075] During peak hours, AC photovoltaic power generation systems and battery energy storage systems are used to charge electric vehicles first.

[0076] This application has the following six working modes: 1. Normal operation with satisfaction rate: AC distribution cabinet + AC photovoltaic power generation system + battery energy storage system = old AC charging pile + new AC charging pile + load; 2. The AC photovoltaic power generation system has no power: AC distribution cabinet + battery energy storage system = old AC charging pile + new AC charging pile + load; 3. The power of the battery energy storage system is lower than the low power threshold: AC distribution cabinet + AC photovoltaic power generation system = old AC charging pile + new AC charging pile + load; 4. The AC distribution cabinet charges the battery energy storage system: AC distribution cabinet = battery energy storage system + old AC charging pile + new AC charging pile + load; 5. The AC distribution cabinet and AC photovoltaic power generation system charge the battery energy storage system: AC distribution cabinet + AC photovoltaic power generation system = battery energy storage system + old AC charging pile + new AC charging pile + load; 6. The AC photovoltaic power generation system and the battery energy storage system supply power to the charging pile: AC photovoltaic power generation system + battery energy storage system = old AC charging pile + new AC charging pile + load.

[0077] In summary, the advantages of the present invention are:

[0078] By setting up an AC photovoltaic power generation system, an energy storage inverter and a battery energy storage system, it is possible to use light energy to charge electric vehicles and battery energy storage systems. The energy storage inverter can invert the electric energy in the battery energy storage system to charge electric vehicles. The peak-shaving and valley-filling strategy created by the energy management system can be used to intelligently charge the battery energy storage system, limiting the maximum power output of the AC distribution cabinet. Ultimately, the output power can be increased without increasing the pressure on the power distribution network. That is, there is no need to expand the capacity of the power grid or modify the lines, and the number of charging piles can be increased, thereby charging more electric vehicles.

[0079] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A charging method, characterized in that: include: Step 1: Create a peak load shifting strategy and set a low power threshold. Step 2: Calculate the required charging power of the electric vehicle based on the charging parameters of the electric vehicle; Step 3: Determine whether the power grid is online through the AC power distribution cabinet. If so, proceed to step 4; if not, disconnect the AC power distribution cabinet from the power grid, and control the AC photovoltaic power generation system and the battery energy storage system to charge the electric vehicle based on the charging demand power. Step 4: Determine whether the power level of the battery energy storage system is lower than the low power threshold. If so, proceed to step 5; otherwise, proceed to step 6. Step 5: Determine whether the charging demand power is greater than the output power of the AC photovoltaic power generation system. If so, use the AC photovoltaic power generation system to charge the electric vehicle, and then use the AC power distribution cabinet and the AC photovoltaic power generation system to charge the electric vehicle and the battery energy storage system based on the peak shaving and valley filling strategy and the maximum power. If not, use the AC photovoltaic power generation system to charge the electric vehicle and the battery energy storage system. Step 6: Determine whether the required charging power is greater than the sum of the output powers of the AC photovoltaic power generation system and the battery energy storage system. If so, use the AC power distribution cabinet, the AC photovoltaic power generation system, and the battery energy storage system to charge the electric vehicle in combination with the maximum power; if not, use the AC photovoltaic power generation system and the battery energy storage system to charge the electric vehicle. The maximum power is the sum of the rated powers of all old AC charging piles; The peak-to-valley-filling strategy specifically involves setting time periods corresponding to normal, valley, and peak periods, and determining whether the current time falls within normal, valley, or peak periods. If the current time falls within normal, valley, or peak periods, the AC power distribution cabinet is used to draw power from the grid to charge the electric vehicle, and the battery energy storage system is not charged via the AC power distribution cabinet. If the current time falls within valley periods, the AC power distribution cabinet is used to draw power from the grid to charge the electric vehicle and the battery energy storage system. If the current time falls within peak periods, the AC photovoltaic power generation system and the battery energy storage system are preferentially used to charge the electric vehicle. The charging parameters include at least the maximum allowable total charging voltage of the power battery system, the maximum allowable charging current of the power battery system, the maximum allowable charging voltage of a single cell, the maximum allowable temperature of a single cell, the current voltage of a single cell, the current voltage of the power battery system, the real-time SOC of a single cell, and the real-time SOC of the power battery system.

2. A charging method according to claim 1, characterized in that: The step 6 then includes: After judging based on the charging parameters that the electric vehicle is fully charged, the AC photovoltaic power generation system has no energy output, and the battery energy storage system reaches a preset SOC, the power output of the AC distribution cabinet, the AC photovoltaic power generation system, or the battery energy storage system is stopped.

3. A charging method according to claim 1, characterized in that: The step 1 includes: After each electric vehicle establishes a connection with the old AC charging pile or the new AC charging pile, the old AC charging pile or the new AC charging pile interacts with the electric vehicle in real time to receive charging parameters of the electric vehicle.

4. A solar storage and charging system, characterized in that: include: An AC distribution cabinet; At least one old AC charging pile connected to the AC power distribution cabinet; A charging pile controller connected to the AC power distribution cabinet and the old AC charging pile; At least one new AC charging pile connected to the charging pile controller; an AC photovoltaic power generation system connected to the old AC charging pile and the charging pile controller; an energy storage converter connected to the AC power distribution cabinet, the old AC charging pile, the charging pile controller, and the AC photovoltaic power generation system; a battery energy storage system connected to the energy storage converter; an energy management system connected to the AC power distribution cabinet, the charging pile controller, the old AC charging pile, the new AC charging pile, the AC photovoltaic power generation system, the energy storage converter, and the battery energy storage system; The energy management system implements each step of a charging method according to any one of claims 1 to 3.

5. The solar storage and charging system according to claim 4, characterized in that: The AC photovoltaic power generation system comprises: a photovoltaic controller, connected to the old AC charging pile, the charging pile controller, and the energy management system respectively; A set of photovoltaic components is connected to the photovoltaic controller.

6. The solar storage and charging system according to claim 4, characterized in that: The battery energy storage system comprises: a battery management system, connected to the energy storage converter and the energy management system respectively; A plurality of lithium iron phosphate batteries are respectively connected to the battery management system and the energy storage converter.

7. The solar storage and charging system according to claim 4, characterized in that: The AC power distribution cabinet is provided with an AC bidirectional meter.

8. The solar storage and charging system according to claim 4, characterized in that: Also includes: An uninterruptible power supply is connected to the energy management system.

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