Charging station capacity expansion system and method based on energy storage and transformer dynamic load management

Abstract

The invention discloses a charging station capacity expansion system and method based on energy storage and transformer dynamic load management. The system comprises an energy storage system, an energy management system between a transformer and the energy storage system, a newly added direct current charging gun and a charging settlement module. The energy storage system is responsible for charging from a charging station transformer and discharging to the direct current charging gun after boosting; the energy management system between the transformer and the energy storage system is responsible for controlling the energy storage system to supplement electricity through a charging station transformer in an electricity price valley period according to the stored electric quantity, the current capacity of the transformer, the electricity price peak and valley period and a specific dynamic charging and discharging strategy when the capacity of the transformer is surplus; or the direct current charging gun which needs to perform external charging work is discharged in the peak period of electricity utilization. According to the method, under the condition that the capacity of an existing charging station transformer is not transformed, the redundant electric quantity is absorbed and stored through energy storage in the low ebb period, discharging in the peak period and dynamic load absorption and storage of the energy storage system and the transformer in the peak period, the operation efficiency of the charging station is improved, and the capacity expansion cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicle charging, and in particular relates to a charging station capacity expansion system and method based on energy storage and transformer dynamic load management. Background Art

[0002] With the rapid development of related technologies such as power batteries and vehicle control software, new energy vehicles are becoming increasingly popular and becoming the preferred means of transportation. In order to meet the increasing demand for charging of new energy vehicles, charging stations of all sizes will be built in various areas of towns and various service areas on highways in the future.

[0003] The core contradictions currently faced by new energy vehicle charging stations are as follows:

[0004] 1. Transformer capacity limitation: The capacity of the charging station transformer is fixed and cannot meet the power demand of more charging guns during the peak charging period. Transformer expansion requires additional investment and time, or some charging station transformers do not have expansion plans.

[0005] 2. Load volatility: The load of charging piles is low during off-peak periods (such as nighttime), and the transformer capacity is idle, but the load is saturated during peak periods (daytime), resulting in a limited number of charging guns. At the same time, during peak charging, due to the displacement of charging vehicles, the charging guns are idle and the charging current of charging vehicles changes, and some transformers are not running at full load.

[0006] Most existing solutions involve directly expanding the transformer capacity and adding charging piles, but such methods are costly and require complicated approvals. Some solutions also attempt to use energy storage systems to reduce peak loads, but such methods do not take into account the dynamic load characteristics of charging stations. Not only is the transformer capacity utilization rate low, but there is also a lack of direct linkage with the charging gun power supply.

[0007] In addition, the added energy storage system has limitations in its use of nighttime valley charging and peak discharge, which prevents the equipment from being fully utilized and fails to maximize the peak-shaving and valley-filling effects of the energy storage system on the transformer capacity, thus extending the equipment investment payback period. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a charging station expansion system and method based on energy storage and transformer dynamic load management. Without modifying the capacity of the existing charging station transformer, the system utilizes energy storage during off-peak periods, discharges during peak periods, and dynamically adjusts the energy storage system and the dynamic load of the transformer during peak periods to absorb and store excess electricity, thereby improving the operating efficiency of the charging station and reducing the cost of expansion.

[0009] In order to solve the above technical problems and achieve the above technical effects, the present invention is implemented through the following technical solutions:

[0010] The charging station expansion system based on energy storage and transformer dynamic load management includes: an energy storage system composed of a battery energy storage module and a boost module, an energy management system (EMS) between the transformer and the energy storage system composed of a transformer load detection module and an energy storage system charge and discharge management module, and a newly added DC charging gun and a charging settlement module; among which,

[0011] The battery energy storage module is responsible for storing electric energy through the charging station transformer and outputting electric energy to the DC charging gun;

[0012] The boost module is responsible for boosting the electric energy output by the battery energy storage module to the charging voltage required by the DC charging gun for external charging;

[0013] The transformer load detection module is responsible for real-time monitoring of the load rate of the transformer of the charging station and each original charging gun;

[0014] The energy storage system charge and discharge management module is responsible for real-time monitoring of the stored power of the battery energy storage module, for judging the current capacity of the transformer according to the measured load rate of the transformer and each original charging gun, for judging the peak and valley period of the current electricity price according to the current time of the charging station, and for taking the obtained stored power, current capacity of the transformer and peak and valley period of the electricity price as reference, and according to a specific dynamic charge and discharge strategy, controlling the battery energy storage module to charge through the charging station transformer when the electricity price is low and the transformer capacity is surplus, or to discharge to the DC charging gun that needs to be charged externally during the peak period of electricity consumption;

[0015] The DC charging gun is equipped with multiple ones, and is responsible for charging the boosted electric energy output by the energy storage system to the new energy vehicle that needs to be charged;

[0016] The charging settlement module is responsible for independently charging the electric energy added by the DC charging gun to the new energy vehicle, and can interact with the main system of the charging station.

[0017] Furthermore, the battery energy storage module includes but is not limited to a lithium-ion battery energy storage module, a sodium-ion battery energy storage module or a flywheel energy storage module.

[0018] Furthermore, the boost module outputs 200-1000V adjustable direct current to adapt to different charging protocols.

[0019] Furthermore, the energy storage system adopts energy storage units in the form of energy storage cabinets, and supports on-demand capacity expansion by connecting multiple cabinets in parallel.

[0020] Furthermore, the transformer load detection module includes but is not limited to using a current sensor or a smart meter.

[0021] Furthermore, the DC charging gun is independent of the original charging gun circuit, is directly powered by the energy storage system after being boosted, and supports fast charging protocols including CCS / CHAdeMO.

[0022] Furthermore, the charging settlement module integrates multiple billing units, supports electricity fee settlement methods including code scanning payment and V2G (vehicle-to-grid interaction), and all of them are interoperable with the main system data of the charging station.

[0023] Furthermore, the specific dynamic charging and discharging strategy follows the priority logic of "transformer capacity is prioritized to ensure the power supply of the original charging gun, and the remaining capacity is allocated to the energy storage system", as follows:

[0024] 1) During the low electricity price period, when the storage capacity of the battery energy storage module is lower than the set external charging allowable value, the battery energy storage module is given priority for recharging;

[0025] 2) During the low electricity price period, when the storage capacity of the battery energy storage module is higher than the set external charging allowable value, and all the existing charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority;

[0026] 3) During the low electricity price period, when the battery energy storage module is not fully charged and the original charging gun is idle, the battery energy storage module is given priority for charging;

[0027] 4) During the peak period of electricity prices, when the battery energy storage module is not fully charged, the transformer is not fully loaded, and the original charging gun is idle, the battery energy storage module is given priority for recharging;

[0028] 5) During the peak electricity price period, when the storage capacity of the battery energy storage module is not fully charged but is higher than the set external charging allowable value, and all the original charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority.

[0029] Furthermore, the energy storage system charge and discharge management module sets the load rate thresholds of the transformer of the charging station and each original charging gun, and dynamically adjusts the charge and discharge power of the battery energy storage module through a PID algorithm.

[0030] A charging and discharging management method of the above-mentioned charging station expansion system comprises the following steps:

[0031] Step 1: Before the charging station is activated, the external charging allowable value of the battery energy storage module of the energy storage system and the load rate threshold of the transformer and each original charging gun of the charging station are set through the energy storage system charging and discharging management module of the energy management system between the transformer and the energy storage system;

[0032] Step 2: After the charging station is enabled, the energy storage system charge and discharge management module monitors the storage power of the battery energy storage module in real time, and determines the peak and valley period of the current electricity price according to the current time of the charging station;

[0033] Step 3: After the charging station is activated, the transformer load detection module of the energy management system between the transformer and the energy storage system monitors the load rate of the transformer and each original charging gun of the charging station in real time, and then the energy storage system charge and discharge management module calculates the current capacity of the transformer according to the measured load rate of the transformer and each original charging gun;

[0034] Step 4: During the operation of the charging station, the energy storage system charge and discharge management module uses the monitored storage power information, the current electricity price peak and valley period information, and the calculated current transformer capacity information as references, and then controls the battery energy storage module to charge or discharge according to the built-in specific dynamic charge and discharge strategy; the specific strategy is as follows:

[0035] 1) During the low electricity price period, when the storage capacity of the battery energy storage module is lower than the set external charging allowable value, the battery energy storage module is given priority for recharging;

[0036] 2) During the low electricity price period, when the storage capacity of the battery energy storage module is higher than the set external charging allowable value, and all the existing charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority;

[0037] 3) During the low electricity price period, when the battery energy storage module is not fully charged and the original charging gun is idle, the battery energy storage module is given priority for charging;

[0038] 4) During the peak period of electricity prices, when the battery energy storage module is not fully charged, the transformer is not fully loaded, and the original charging gun is idle, the battery energy storage module is given priority for recharging;

[0039] 5) During the peak electricity price period, when the storage capacity of the battery energy storage module is not fully charged but is higher than the set external charging allowable value, and all the existing charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority;

[0040] Step 5: In the charging mode, the energy storage system charging and discharging management module uses the remaining capacity of the transformer to charge the battery energy storage module. The charging power is calculated by the energy storage system charging and discharging management module according to the real-time load rate of the transformer and each original charging gun and the set load rate threshold through the PID algorithm.

[0041] Step 6: In the external charging mode, the energy storage system charge and discharge management module uses the stored electric energy of the battery energy storage module to discharge externally, and the discharge power is calculated by the energy storage system charge and discharge management module according to the real-time load rate of the transformer and each original charging gun and the set load rate threshold through the PID algorithm;

[0042] Step 7: During the external discharge process, the boost module of the energy storage system boosts the output electric energy to the charging voltage required for the DC charging gun to charge externally, so as to meet the charging needs of the new energy vehicle;

[0043] Step 8: During the external charging process of the DC charging gun, the charging settlement module records the power consumption in real time, and calculates the corresponding charging fee of the DC charging gun after the external charging is completed, and feeds back the power consumption and fee information to the charging station main system.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention can quickly expand the capacity of an existing charging station by adding a battery energy storage system, an energy management system and other DC charging guns in the charging station without modifying the capacity of the existing transformer. The on-site construction is simple, the expansion cost is reduced, the electricity sales volume is increased, and the investment return period is shortened.

[0046] The present invention adopts a specific dynamic charging and discharging strategy and follows the priority logic of "transformer capacity is prioritized to ensure the power supply of the original charging gun, and the remaining capacity is allocated to the energy storage system". When the electricity price is low and the charging station transformer capacity is surplus, the battery energy storage system absorbs the excess power of the charging station transformer for replenishment. When the discharge demand of the charging gun increases, the DC charging gun is directly boosted and discharged, thereby improving the utilization rate of the existing transformer capacity, alleviating charging peak congestion, and improving the operating efficiency of the charging station.

[0047] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0049] Figure 1 This is a system architecture diagram of the charging station expansion system based on energy storage and transformer dynamic load management of the present invention and an overall architecture diagram after being installed in the charging station.

[0050] Figure 2 The internal structure and external connection relationship diagram of the energy storage system in the charging station expansion system of the present invention;

[0051] Figure 3 This is a diagram of the internal structure and external connection relationship of the energy management system between the transformer and the energy storage system in the charging station expansion system of the present invention.

[0052] Explanation of the marks in the figure: 1. Energy storage system; 101. Battery energy storage module; 102. Boost module; 2. Energy management system between transformer and energy storage system; 201. Transformer load detection module; 202. Energy storage system charge and discharge management module; 3. DC charging gun; 4. Charging settlement module; 5. Transformer; 6. Original charging gun. DETAILED DESCRIPTION

[0053] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings so that the purpose, features and advantages of the invention can be more clearly understood. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0054] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of these specific details. In other cases, well-known devices, structures, and techniques associated with the present application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0055] Unless the context requires otherwise, throughout the specification and claims, the word "comprise" and variations such as "include" and "have" should be construed in an open, inclusive sense, ie, should be interpreted as "including, but not limited to."

[0056] References throughout the specification to "one embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "in an embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any manner in one or more embodiments.

[0057] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should be noted that the term "or" is generally employed in its sense including "and / or" unless the context clearly dictates otherwise.

[0058] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0059] See also Figure 1 As shown, the present invention provides a charging station expansion system based on energy storage and transformer dynamic load management, which mainly includes a new energy storage system 1 added on the basis of the transformer 5 and the original charging gun 6 of the charging station, an energy management system 2 (EMS) between the transformer and the energy storage system, a DC charging gun 3 and a charging settlement module 4.

[0060] See also Figure 2 As shown, the energy storage system 1 is composed of a battery energy storage module 101 and a boost module 102 .

[0061] The battery energy storage module 101 is responsible for storing electric energy through the transformer 5 of the charging station and outputting electric energy to the DC charging gun 3 .

[0062] Preferably, the battery energy storage module 101 may be a lithium-ion battery energy storage module, a sodium-ion battery energy storage module, a flywheel energy storage module or other energy storage modules.

[0063] The boost module 102 is responsible for boosting the electric energy output by the battery energy storage module 101 to the charging voltage required by the DC charging gun 3 for external charging.

[0064] Preferably, the boost module 102 outputs 200-1000V adjustable direct current, so as to be adaptable to different charging protocols.

[0065] The energy storage system 1 is designed as an energy storage unit in the form of an energy storage cabinet, which supports parallel connection of multiple cabinets. When expanding the capacity, energy storage units can be added in parallel as needed.

[0066] See also Figure 3 As shown, the energy management system 2 between the transformer and the energy storage system is composed of a transformer load detection module 201 and an energy storage system charge and discharge management module 202 .

[0067] The transformer load detection module 201 is responsible for real-time monitoring of the load rate of the transformer 5 and each existing charging gun 6 of the charging station.

[0068] Preferably, the transformer load detection module 201 may adopt a current sensor or a smart meter, etc.

[0069] The energy storage system charge and discharge management module 202, as the core of the system, is responsible for multiple tasks, including:

[0070] Responsible for real-time monitoring of the storage power of the battery energy storage module 101;

[0071] Responsible for determining the current capacity of the transformer according to the measured load rates of the transformer 5 and each original charging gun 6;

[0072] Responsible for determining the peak and valley period of the current electricity price based on the current time of the charging station;

[0073] It is responsible for taking the obtained stored power, current capacity of the transformer and peak and valley periods of electricity prices as references, and according to a specific dynamic charging and discharging strategy, controlling the battery energy storage module 101 to charge through the charging station transformer 5 when the electricity price is low and the transformer capacity is surplus, or to discharge to the DC charging gun 3 that needs to be charged externally during peak electricity consumption.

[0074] Preferably, the specific dynamic charging and discharging strategy follows the priority logic of "transformer capacity is prioritized to ensure the power supply of the original charging gun, and the remaining capacity is allocated to the energy storage system", which is as follows:

[0075] 1) During the low electricity price period, when the storage power of the battery energy storage module 101 is lower than the set external charging allowable value, the battery energy storage module 101 is preferentially charged;

[0076] 2) During the low electricity price period, when the storage capacity of the battery energy storage module 101 is higher than the set external charging allowable value, and all the existing charging guns are working on external charging, the newly added DC charging gun 3 is given priority for external charging;

[0077] 3) During the low electricity price period, when the battery energy storage module 101 is not fully charged and the original charging gun 6 is idle, the battery energy storage module 101 is given priority for charging;

[0078] 4) During the peak period of electricity prices, when the battery energy storage module 101 is not fully charged, the transformer 5 is not fully loaded, and the original charging gun 6 is idle, the battery energy storage module 101 is given priority for recharging;

[0079] 5) During the peak electricity price period, when the stored power of the battery energy storage module 101 is not fully charged but is higher than the set external charging allowable value, and all the original charging guns 6 are working on external charging, the external charging of the newly added DC charging gun 3 is given priority.

[0080] The energy storage system charge and discharge management module 202 sets the load rate thresholds of the transformer 5 of the charging station and each existing charging gun 6, and dynamically adjusts the charge and discharge power of the battery energy storage module 101 through a PID algorithm.

[0081] The DC charging gun 3 is equipped with multiple ones and is responsible for injecting the boosted electric energy output by the energy storage system 1 into the new energy vehicle that needs to be charged.

[0082] Preferably, the DC charging gun 3 is independent of the original charging gun circuit, is powered directly by the energy storage system 1 after boosting, and supports fast charging protocols including CCS / CHAdeMO.

[0083] The charging settlement module 4 is responsible for independently charging the electric energy added by the DC charging gun 3 to the new energy vehicle, and can interact with the main system of the charging station.

[0084] Preferably, the charging settlement module 4 integrates a variety of billing units, supports multiple electricity fee settlement methods such as code scanning payment and V2G (vehicle-to-grid interaction), and all of them are interoperable with the main system data of the charging station.

[0085] A charging and discharging management method of the charging station expansion system as described above comprises the following steps:

[0086] Step 1: Before the charging station is activated, the external charging allowable value of the battery energy storage module 101 of the energy storage system 1 and the load rate threshold of the transformer 5 and each original charging gun 6 of the charging station are set respectively through the energy storage system charging and discharging management module 202 of the energy management system 2 between the transformer and the energy storage system;

[0087] Step 2: After the charging station is enabled, the energy storage system charge and discharge management module 202 monitors the storage power of the battery energy storage module 101 in real time, and determines the peak and valley period of the current electricity price according to the current time of the charging station;

[0088] Step 3: After the charging station is activated, the transformer load detection module 201 of the energy management system 2 between the transformer and the energy storage system monitors the load rate of the transformer 5 and each original charging gun 6 of the charging station in real time, and then the energy storage system charge and discharge management module 202 calculates the current capacity of the transformer according to the measured load rate of the transformer 5 and each original charging gun 6;

[0089] Step 4: During the operation of the charging station, the energy storage system charge and discharge management module 202 uses the monitored storage power information, the current electricity price peak and valley period information, and the calculated current transformer capacity information as references, and then controls the battery energy storage module 101 to charge or discharge according to the built-in specific dynamic charge and discharge strategy; the specific strategy is as follows:

[0090] 1) During the low electricity price period, when the storage power of the battery energy storage module 101 is lower than the set external charging allowable value, the battery energy storage module 101 is preferentially charged;

[0091] 2) During the low electricity price period, when the storage capacity of the battery energy storage module 101 is higher than the set external charging allowable value, and all the existing charging guns 6 are working on external charging, the external charging of the newly added DC charging gun 3 is given priority;

[0092] 3) During the low electricity price period, when the battery energy storage module 101 is not fully charged and the original charging gun 6 is idle, the battery energy storage module 101 is given priority for charging;

[0093] 4) During the peak period of electricity prices, when the battery energy storage module 101 is not fully charged, the transformer 5 is not fully loaded, and the original charging gun 6 is idle, the battery energy storage module 101 is given priority for recharging;

[0094] 5) During the peak electricity price period, when the stored power of the battery energy storage module 101 is not fully charged but is higher than the set external charging allowable value, and when all the original charging guns 6 are working on external charging, the external charging of the newly added DC charging gun 3 is given priority;

[0095] Step 5: In the power replenishment mode, the energy storage system charge and discharge management module 202 uses the remaining capacity of the transformer 5 to replenish the battery energy storage module 101. The power replenishment power is calculated by the energy storage system charge and discharge management module 202 according to the real-time load rate of the transformer 5 and each original charging gun 6 and the set load rate threshold through the PID algorithm;

[0096] Step 6: In the external charging mode, the energy storage system charge and discharge management module 202 uses the stored electric energy of the battery energy storage module 101 to discharge externally, and the discharge power is calculated by the energy storage system charge and discharge management module 202 according to the real-time load rate of the transformer 5 and each original charging gun 6 and the set load rate threshold through the PID algorithm;

[0097] Step 7: During the external discharge process, the boost module 102 of the energy storage system 1 boosts the output electric energy to the charging voltage required by the DC charging gun 3 for external charging to meet the charging needs of the new energy vehicle;

[0098] Step 8: During the external charging process of the DC charging gun 3, the charging settlement module 4 records the power consumption in real time, and calculates the corresponding charging fee of the DC charging gun 3 after the external charging is completed, and feeds back the power consumption and fee information to the charging station main system.

[0099] Take a charging station with a 630kVA transformer supporting four 120kW charging guns as an example. After installing a 100kWh battery energy storage module (energy storage cabinet), a boost module, a transformer load detection module, an energy storage system charge and discharge management module, two 180kW DC charging guns and two corresponding charging settlement modules of the present invention:

[0100] Nighttime electricity price low period: The transformer load is 30%, and the energy storage system charge and discharge management module controls the battery energy storage module to supplement power at 200kW for 2.5 hours.

[0101] During peak daytime electricity prices: transformer load reaches 95%, the energy storage system charge and discharge management module controls the battery energy storage module to discharge at 360kW (2×180kW), and two 180kW DC charging guns are used.

[0102] Effect after expansion: The transformer utilization rate of this charging station increased from 30%-100% to 70%-95%, the number of charging guns increased by 50%, and the investment cost was only 1 / 3 of the traditional transformer expansion method.

[0103] In summary, the present invention has the following three design highlights:

[0104] 1. Dynamic load response: The present invention adjusts energy storage charging and discharging based on real-time transformer load to maximize the capacity utilization of existing transformers.

[0105] 2. Off-grid power supply: The energy storage cabinet of the present invention directly outputs to the DC charging gun through the boost module, without the need for additional charging module modification.

[0106] 3. Incremental capacity expansion: The number of newly added DC charging guns in the present invention is positively correlated with the energy storage capacity and the idle capacity of the transformer, and can be expanded on demand.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Charging station expansion system based on energy storage and transformer dynamic load management, characterized by: include: The energy storage system consists of a battery energy storage module and a boost module, an energy management system between the transformer and the energy storage system consisting of a transformer load detection module and an energy storage system charge and discharge management module, and a newly added DC charging gun and charging settlement module; among them, The battery energy storage module is responsible for storing electric energy through the charging station transformer and outputting electric energy to the DC charging gun; The boost module is responsible for boosting the electric energy output by the battery energy storage module to the charging voltage required by the DC charging gun for external charging; The transformer load detection module is responsible for real-time monitoring of the load rate of the transformer of the charging station and each original charging gun; The energy storage system charge and discharge management module is responsible for real-time monitoring of the stored power of the battery energy storage module, for judging the current capacity of the transformer according to the measured load rate of the transformer and each original charging gun, for judging the peak and valley period of the current electricity price according to the current time of the charging station, and for taking the obtained stored power, current capacity of the transformer and peak and valley period of the electricity price as reference, and according to a specific dynamic charge and discharge strategy, controlling the battery energy storage module to charge through the charging station transformer when the electricity price is low and the transformer capacity is surplus, or to discharge to the DC charging gun that needs to be charged externally during the peak period of electricity consumption; The DC charging gun is equipped with multiple ones, and is responsible for charging the boosted electric energy output by the energy storage system to the new energy vehicle that needs to be charged; The charging settlement module is responsible for independently charging the electric energy added by the DC charging gun to the new energy vehicle, and can interact with the main system of the charging station.

2. The charging station capacity expansion system based on energy storage and transformer dynamic load management according to claim 1 is characterized in that: The battery energy storage module includes but is not limited to a lithium-ion battery energy storage module, a sodium-ion battery energy storage module or a flywheel energy storage module.

3. The charging station expansion system based on energy storage and transformer dynamic load management according to claim 1 is characterized in that: The boost module outputs 200-1000V adjustable DC power to adapt to different charging protocols.

4. The charging station capacity expansion system based on energy storage and transformer dynamic load management according to claim 1 is characterized in that: The energy storage system adopts energy storage units in the form of energy storage cabinets, and supports on-demand capacity expansion by connecting multiple cabinets in parallel.

5. The charging station capacity expansion system based on energy storage and transformer dynamic load management according to claim 1 is characterized in that: The transformer load detection module includes but is not limited to using a current sensor or a smart meter.

6. The charging station expansion system based on energy storage and transformer dynamic load management according to claim 1 is characterized in that: The DC charging gun is independent of the original charging gun circuit, is directly powered by the energy storage system after being boosted, and supports fast charging protocols including CCS / CHAdeMO.

7. The charging station capacity expansion system based on energy storage and transformer dynamic load management according to claim 1 is characterized in that: The charging settlement module integrates multiple billing units, supports electricity fee settlement methods including code scanning payment and V2G, and all of them are interoperable with the main system data of the charging station.

8. The charging station expansion system based on energy storage and transformer dynamic load management according to claim 1 is characterized in that: The specific dynamic charging and discharging strategy follows the priority logic of "transformer capacity is prioritized to ensure the power supply of the original charging gun, and the remaining capacity is allocated to the energy storage system", as follows: 1) During the low electricity price period, when the storage capacity of the battery energy storage module is lower than the set external charging allowable value, the battery energy storage module is given priority for recharging; 2) During the low electricity price period, when the storage capacity of the battery energy storage module is higher than the set external charging allowable value, and all the existing charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority; 3) During the low electricity price period, when the battery energy storage module is not fully charged and the original charging gun is idle, the battery energy storage module is given priority for charging; 4) During the peak period of electricity prices, when the battery energy storage module is not fully charged, the transformer is not fully loaded, and the original charging gun is idle, the battery energy storage module is given priority for recharging; 5) During the peak electricity price period, when the storage capacity of the battery energy storage module is not fully charged but is higher than the set external charging allowable value, and all the original charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority.

9. The charging station capacity expansion system based on energy storage and transformer dynamic load management according to claim 1, characterized in that: The energy storage system charge and discharge management module sets the load rate thresholds of the transformer of the charging station and each original charging gun, and dynamically adjusts the charge and discharge power of the battery energy storage module through the PID algorithm.

10. A charging and discharging management method for a charging station expansion system according to claims 1 to 9, characterized in that: The steps include: Step 1: Before the charging station is activated, the external charging allowable value of the battery energy storage module of the energy storage system and the load rate threshold of the transformer and each original charging gun of the charging station are set through the energy storage system charging and discharging management module of the energy management system between the transformer and the energy storage system; Step 2: After the charging station is enabled, the energy storage system charge and discharge management module monitors the storage power of the battery energy storage module in real time, and determines the peak and valley period of the current electricity price according to the current time of the charging station; Step 3: After the charging station is activated, the transformer load detection module of the energy management system between the transformer and the energy storage system monitors the load rate of the transformer and each original charging gun of the charging station in real time, and then the energy storage system charge and discharge management module calculates the current capacity of the transformer according to the measured load rate of the transformer and each original charging gun; Step 4: During the operation of the charging station, the energy storage system charge and discharge management module uses the monitored storage power information, the current electricity price peak and valley period information, and the calculated current transformer capacity information as references, and then controls the battery energy storage module to charge or discharge according to the built-in specific dynamic charge and discharge strategy; the specific strategy is as follows: 1) During the low electricity price period, when the storage capacity of the battery energy storage module is lower than the set external charging allowable value, the battery energy storage module is given priority for recharging; 2) During the low electricity price period, when the storage capacity of the battery energy storage module is higher than the set external charging allowable value, and all the existing charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority; 3) During the low electricity price period, when the battery energy storage module is not fully charged and the original charging gun is idle, the battery energy storage module is given priority for charging; 4) During the peak period of electricity prices, when the battery energy storage module is not fully charged, the transformer is not fully loaded, and the original charging gun is idle, the battery energy storage module is given priority for recharging; 5) During the peak electricity price period, when the storage capacity of the battery energy storage module is not fully charged but is higher than the set external charging allowable value, and all the existing charging guns are working on external charging, the external charging of the newly added DC charging guns shall be given priority; Step 5: In the charging mode, the energy storage system charging and discharging management module uses the remaining capacity of the transformer to charge the battery energy storage module. The charging power is calculated by the energy storage system charging and discharging management module according to the real-time load rate of the transformer and each original charging gun and the set load rate threshold through the PID algorithm. Step 6: In the external charging mode, the energy storage system charge and discharge management module uses the stored electric energy of the battery energy storage module to discharge externally, and the discharge power is calculated by the energy storage system charge and discharge management module according to the real-time load rate of the transformer and each original charging gun and the set load rate threshold through the PID algorithm; Step 7: During the external discharge process, the boost module of the energy storage system boosts the output electric energy to the charging voltage required for the DC charging gun to charge externally, so as to meet the charging needs of the new energy vehicle; Step 8: During the external charging process of the DC charging gun, the charging settlement module records the power consumption in real time, and calculates the corresponding charging fee of the DC charging gun after the external charging is completed, and feeds back the power consumption and fee information to the charging station main system.

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