Power optimization control method and system based on SST bidirectional flexible interconnection

Abstract

This invention discloses a power optimization control method and system based on SST bidirectional flexible interconnection, belonging to the field of electric vehicle charging technology. The method includes: constructing a bidirectional interconnected DC architecture for both service areas, with the output sides of both SSTs connected to a DC bus, and charging piles suspended on the DC bus; real-time monitoring of the grid status, with the SST on the normal service area supplying power to the lost side when one service area loses power; during normal operation of both service areas, performing SST-level power optimization, including light load merging strategy, overload support strategy, and full load power limiting strategy to ensure stable system operation; and performing charging pile-level power optimization based on SST optimization, dynamically integrating charging loads, prioritizing full-power operation of online charging piles, and shutting down unloaded or lightly loaded charging piles. This invention solves the charging tidal phenomenon in service areas, realizes capacity sharing and mutual assistance, and improves power supply reliability and equipment utilization.

Description

Technical Field

[0001] This invention belongs to the field of solid-state transformer technology, specifically relating to a power optimization control method and system based on SST bidirectional flexible interconnection. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the number of new energy vehicles and their driving range continue to increase. Charging infrastructure, as a core support for the promotion and application of new energy vehicles, directly impacts the sustainable development of the industry. Among these, highway service areas, as key replenishment nodes for long-distance travel of new energy vehicles, play a crucial role in promoting the popularization of new energy vehicles and alleviating users' charging anxiety during long-distance travel.

[0003] However, the current charging infrastructure sector at highway service areas faces multiple prominent technical challenges, severely restricting the improvement and sustainable development of charging service capabilities. Specific technical issues are as follows: First, there is a significant contradiction between charging demand and power supply capacity configuration, resulting in insufficient system flexibility. The charging demand at service areas on both sides of the highway exhibits a clear imbalance, with the tidal effect of charging demand being particularly pronounced during holidays. However, due to the inherent constraints of the existing route layout and transformer capacity, power supply resources cannot be shared between service areas on both sides. This leads to a rigid power supply capacity configuration for a single service area, which cannot be flexibly adjusted according to the dynamic changes in charging demand. Consequently, a supply-demand imbalance occurs, with charging resources scarce in one service area and power supply capacity idle in the other.

[0004] Secondly, the existing charging system architecture suffers from low energy conversion efficiency and significant energy waste. The current mainstream implementation of charging systems in highway service areas adopts a traditional architecture combining power frequency transformers and charging equipment. This architecture involves numerous energy conversion stages and long energy transmission links, resulting in low overall system energy efficiency. Especially under light load conditions, the system efficiency can only be maintained at a low level of 88%–91%, with a large amount of energy lost during conversion and transmission. This not only increases the operating costs of charging services but also fails to meet the requirements of energy conservation and emission reduction for industrial development.

[0005] Third, the operational efficiency and reliability of charging systems still need further improvement. Currently, most highway service area charging systems are built on traditional power electronic equipment. In the long run, these systems not only struggle to overcome efficiency bottlenecks but also face insufficient operational reliability, making them prone to equipment failures and charging interruptions. This affects the user charging experience and further restricts the large-scale, high-quality development of highway charging services.

[0006] In summary, existing highway service area charging infrastructure suffers from technical deficiencies such as rigid capacity configuration, low energy conversion efficiency, and insufficient system reliability. These deficiencies, when combined, severely limit the improvement of highway charging service capabilities and fail to meet the charging demands of long-distance travel in the context of the rapid development of the new energy vehicle industry. Therefore, there is an urgent need for a technical solution that can effectively address the aforementioned technical problems and provide efficient, flexible, and reliable technical support for highway service area charging services. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of limited charging capacity, inability to share capacity on the opposite side, and low charging efficiency in highway service areas. It proposes a power optimization control method and system based on bidirectional flexible interconnection of solid-state transformers (SST). Under the premise of meeting basic charging needs, it increases the number of charging spaces, maximizes the utilization of solid-state transformer (SST) capacity, realizes bidirectional energy optimization in service areas, and improves charging efficiency.

[0008] This invention is achieved through the following technical solution: In a first aspect, this invention provides a power optimization control method based on SST bidirectional flexible interconnect, comprising: Based on the constructed bidirectional interconnected DC architecture of the two-sided service areas, charging load data of the two-sided service areas are obtained in real time. Based on the charging load data of both service areas, power optimization control is performed on the SST of both service areas according to the preset strategy. Based on the power optimization control results of the dual-side service area SST, the charging load of the charging pile is dynamically integrated, prioritizing the charging piles in online operation to reach full power operation, and shutting down the charging piles that are unloaded or lightly loaded, thereby realizing the power optimization control of the charging pile. The preset strategies include: When the preset light load conditions are met, the charging load of one service area SST is controlled to operate within the preset load range, and the SST of one service area is controlled to shut down. When the charging load of one service area exceeds the rated capacity of the SST, the SST of that service area is controlled to operate at full power, and the load power exceeding its rated capacity is replenished across the region through the SST of the other service area. When the charging load of both service areas exceeds the rated capacity of the SST, the SST in both service areas is controlled to operate at the rated capacity, and the power of the charging pile is limited.

[0009] Preferably, the preset load range is 40%-50% of the SST rated capacity.

[0010] Preferably, the preset light load conditions include: the charging load of a single service area is 0; the total charging load of both service areas is less than or equal to 50% of the rated capacity of a single SST unit.

[0011] Preferably, before acquiring the charging load data of both service areas in real time, the method further includes: Real-time monitoring of the power supply status of the medium-voltage AC power grid in both service areas; If a power grid failure is detected in only one service area, the SST in the service area on the side with the power failure will be shut down and isolated from the power grid. The SST in the other service area, which is operating normally, will be used as a voltage source to build a DC bus to provide power support for the charging load of the service area on the side with the power failure. If it is detected that the power grids of both service areas are supplying power normally, the SST power optimization control mode of both service areas will be executed.

[0012] Preferably, the dynamic integration of the charging load of the charging pile specifically includes: Obtain the real-time operating power of all online charging piles in one service area and calculate the total charging load of that service area; Based on the ratio of the total charging load to the rated power of a single charging pile, determine the minimum number of charging piles required to carry the current total load. ; If the number of charging piles currently actually in operation is greater than Then, the integration operation will be performed, including: Concentrate the current total charging load to On the charging pile, to make it operational Once one charging stack reaches full power operation, it controls the other charging stacks to shut down. If the number of charging piles currently operating online is equal to If the real-time operating power of each charging pile exceeds half of its rated power, the current operating state will remain unchanged.

[0013] Preferably, the current total charging load is concentrated to On the charging pile, to make it operational The charging pile has reached full power operation, specifically: Divide the total charging load by the rated power of a single charging pile. The integer part of the quotient corresponds to the number of charging piles operating at full power. If the remainder of the division is greater than zero, the charging load corresponding to the remainder is handled by one charging pile, and the remaining charging piles are shut down.

[0014] Preferably, the bidirectional interconnected DC architecture of the dual-side service areas specifically includes: SSTs are configured in both service areas. The input side of each SST is connected to the medium-voltage AC power grid of both service areas, and the output side of the SSTs is connected to the DC bus. Multiple charging piles are connected to the DC bus, and the charging piles are interconnected on the DC side. Among them, the total capacity of the charging piles configured in a single service area is greater than the rated capacity of a single SST.

[0015] Preferably, the total capacity of the charging piles configured in the single-sided service area is twice the rated capacity of the single-sided SST.

[0016] In a second aspect, the present invention provides a power optimization control system based on SST bidirectional flexible interconnect, comprising: Solid-state transformers, multiple charging piles, and controllers are respectively configured in the service areas on both sides; The input side of the solid-state transformer is connected to the medium-voltage AC power grid of the corresponding service area, and the output side of the solid-state transformer is connected to the DC bus. The multiple charging piles are connected to the DC bus, and the charging piles are interconnected on the DC side. The controller is configured to execute the power optimization control method based on SST bidirectional flexible interconnect.

[0017] Preferably, the solid-state transformer has a capacity of 1MW, an input of AC10kV, and an output of DC800V.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a power optimization control method based on bidirectional flexible interconnection of SST (Service Stations). Through a bidirectional interconnected DC architecture in both service areas, it monitors the power supply status of the medium-voltage AC grid and the charging load data on both sides in real time. When one side of the grid loses power, the SST on the normal side provides power support to the side that lost power. When both grids are normal, power optimization control between the two SSTs is completed according to a preset strategy. Then, the load of multiple charging piles on this side is dynamically integrated, prioritizing full-power operation of individual charging piles and shutting down unloaded / lightly loaded charging piles. This invention enables real-time sharing of charging capacity and load balancing in highway bidirectional service areas, effectively solving the problems of limited capacity, tidal charging, and low efficiency in traditional charging systems. Charging efficiency is improved by 3%-5% compared to traditional solutions, while also improving power supply reliability. It is suitable for the efficient and stable operation of charging systems in highway service areas.

[0019] This invention also provides a power optimization control system based on SST bidirectional flexible interconnection. It constructs a bidirectional interconnected DC architecture for both service areas using SST with a common DC bus. The architecture design, employing a bidirectional SST common DC bus and DC-side interconnection of charging piles, establishes a flexible interconnection channel for bidirectional power flow. This breaks the power supply capacity limitation of a single service area, enabling pooled sharing of charging capacity. It provides hardware support for power optimization control, improving system scheduling flexibility and overall power supply capacity. The system can stably execute power optimization control methods, achieving fully automatic power scheduling and load optimization. The hardware architecture and control method work in synergy to ensure that the high-speed service area charging system achieves the technical effects of capacity sharing, efficient operation, and highly reliable power supply.

[0020] Furthermore, this invention limits the optimal operating load range of the SST to 40%-50% of its rated capacity, which ensures that the SST always operates in the highest efficiency range under light load conditions, minimizes SST operating losses, further improves the overall energy conversion efficiency of the system, and avoids energy waste caused by inefficient operation under light load.

[0021] Furthermore, when light load conditions are met, the present invention shuts down one side of the SST, and the other side of the SST independently bears all the charging load on both sides. This can effectively reduce the SST's no-load and light-load operation losses, simplify the system operation topology, and maximize the reduction of system standby losses while ensuring charging power supply, thereby further improving the system's operating economy and overall efficiency.

[0022] Furthermore, by real-time detection of the medium-voltage AC power grid supply status and execution of single-sided power failure support control, this invention can quickly isolate the power failure side SST to prevent power backfeeding in the event of a single-sided grid failure. A stable DC bus is constructed from the normal side SST to supply power to the power failure side, which greatly improves the system's power supply reliability and fault redundancy capability, and enables uninterrupted operation of charging services in both service areas.

[0023] Furthermore, by calculating the minimum number of operating charging piles and performing centralized load consolidation, this invention can ensure that the charging piles always operate at full power, shut down redundant lightly loaded / unloaded charging piles, minimize charging pile operating losses, improve the working efficiency and capacity utilization of charging equipment, and at the same time avoid system oscillation caused by frequent equipment switching.

[0024] Furthermore, this invention configures the total capacity of a single-sided charging pile to be twice the rated capacity of the SST, which can expand the number of charging spaces without increasing the SST capacity, improve the charging service capacity of the service area, and at the same time achieve efficient capacity utilization by relying on power optimization control, taking into account both system expansion and operating efficiency. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a diagram of the power optimization control system architecture based on SST bidirectional flexible interconnection. Figure 2 This is a flowchart of a power optimization control method based on SST bidirectional flexible interconnect. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely for explaining the invention and do not constitute any limitation on the scope of protection of the invention. All modifications, equivalent substitutions, or improvements made based on the concept of this invention should be included within the scope of protection of this invention.

[0028] Power optimization control methods based on SST bidirectional flexible interconnect, such as Figure 1 and Figure 2 As shown, it includes: S1, based on the constructed bidirectional interconnected DC architecture of the two-sided service areas, obtains charging load data of the two-sided service areas in real time; The bidirectional interconnected DC architecture for the dual-side service areas specifically includes: Solid-State Transformers (SSTs) are configured in both service areas. The input side of the SSTs is connected to the medium-voltage AC power grid of both service areas, and the output side of the SSTs is connected to the DC bus. Multiple charging piles are connected to the DC bus, and the charging piles are interconnected on the DC side. Among them, the total capacity of the charging piles configured in a single service area is greater than the rated capacity of a single SST.

[0029] Specifically, acquiring charging load data from both service areas involves: The input current and DC bus voltage of each charging pile in the service area on both sides are collected in real time, the real-time output power of each charging pile is calculated, and the output power data of all charging piles in the service area on both sides are summarized to obtain the charging load data of the service area on both sides. For example, a current sensor and a voltage sensor are set at the DC side input terminal of each charging pile to collect the input current and bus voltage of each charging pile in real time at a sampling frequency of 1kHz. Each charging pile calculates and updates its real-time power value with an adoption period of 100ms. The controller collects power data of the charging pile with a sampling period of 200ms; The controller performs a moving average filter on the power values ​​of the same charging pile for three consecutive cycles to eliminate abnormal data such as communication timeouts or excessively large value jumps. The filtered power data of all charging piles in both service areas are summed to obtain the total charging load data of both service areas.

[0030] In some embodiments, before acquiring charging load data from both service areas in real time, the method further includes: Real-time monitoring of the power supply status of the medium-voltage AC power grid (e.g., 10kV) in both service areas; When a power grid failure is detected on only one side of the service area, the SST of the service area on the side with the power failure is shut down and isolated from the power grid. Meanwhile, the SST on the other side of the service area, which is operating normally, forms a voltage source through interconnected DC buses to provide power support for the charging load of the service area on the side that has lost power.

[0031] By monitoring the power supply status of the medium-voltage AC grid on both sides in real time, the SST on the power failure side can be quickly isolated and power backfeed can be prevented when the power grid on one side fails. The SST on the normal side can provide power support to the power failure side by building a stable voltage source based on the interconnected DC bus. This significantly improves the reliability of the system power supply and the fault redundancy capability, ensuring uninterrupted and stable operation of charging services in both service areas under the condition of a single-side grid failure.

[0032] In some embodiments, the total capacity of the charging piles configured in the single-sided service area is twice the rated capacity of the single-sided SST.

[0033] This double-capacity configuration ensures that even in extreme conditions where one service area loses power and the other SST supplies power alone, the power limiting strategy can still provide basic power supply to the charging loads on both sides, preventing system failure due to insufficient capacity. During normal power supply, this double-capacity configuration also provides sufficient load regulation margin for optimization strategies such as overload support and power integration in steps S2 and S3, enabling the system to fully utilize the mutual capacity advantage of both sides and improve equipment utilization and charging efficiency.

[0034] S2, based on the real-time charging load data of both service areas, performs power optimization control on the SST of both service areas according to the preset strategy; The preset strategies include: (1) Scenario 1: When the preset light load conditions are met, the following control strategy is executed, specifically including: For example, the preset light load condition is defined as any of the following situations occurring: The charging load in a single service area is 0. The total charging load of both service areas is less than or equal to the rated capacity of a single SST unit.

[0035] When the above light load conditions are met, the following control strategy is executed: Control the SST of one service area to operate within a preset load range, or control the SST of one service area to shut down.

[0036] In a preferred embodiment, when the charging load of one service area is 0, the SST of that service area is controlled to be in standby or off state and electrically isolated from the DC bus to reduce power loss. The SST of the other service area then undertakes the entire charging load of both service areas, and the charging load undertaken operates within a preset load range, wherein the preset load range is 40%-50% of the rated capacity of the SST, and is powered through the DC bus. This control method eliminates unnecessary transformer no-load losses to the greatest extent.

[0037] As another preferred implementation, when the total charging load of both service areas is less than or equal to the rated capacity of a single SST, the power of the SST in one service area is adjusted so that the charging load it undertakes operates within a preset load range, while the SST in the other service area is shut down. The preset load range is 40%-50% of the rated capacity of the SST. This strategy greatly reduces the inefficient operation loss and power consumption of the SST itself.

[0038] One strategy involves shutting down the SST in one service area and isolating it from the DC bus, while the SST in the other service area independently constructs the DC bus voltage to handle the entire charging load of both service areas. This strategy significantly reduces the transformer's no-load loss and auxiliary power consumption.

[0039] For example, if the total load is 0.4MW, the SST of one service area is controlled to output 0.4MW, while the SST of the other side is on standby or stopped. At this time, the SST of one service area is operating in the high-efficiency range of 40% load, avoiding the high-loss state of both SSTs operating at the extremely low load of 20% at the same time.

[0040] (2) Scenario 2: Support strategy for heavy load on one side and light load on the other side When the charging load of one service area exceeds the rated capacity of the SST on that side, and the charging load of the other service area is low, the SST on that service area is controlled to operate at full power, and the load power exceeding the rated capacity of its SST is supplied across areas through the interconnected DC bus via the SST on the other service area. (3) Scenario 3: Power limiting strategy with full load on both sides When the charging load in both service areas exceeds the rated capacity of the SST, the SST in both service areas will be controlled to operate at the rated capacity, and power limiting control will be implemented on the charging pile. Under this condition, SST will no longer have cross-zone adjustment space and will instead enter the power limiting control mode for the charging pile, appropriately reducing the distribution current of each charging gun to ensure that SST does not trip and shut down due to overload.

[0041] S3, based on SST power optimization control, further dynamically integrates the charging load of the charging pile, prioritizes the charging piles running online to reach full power operation, and shuts down the charging piles that are unloaded or lightly loaded, thus realizing the power optimization control of the charging pile. In some embodiments, the dynamic integration of the charging load of the charging pile specifically includes: Obtain the real-time operating power of all online charging piles within one side of the service area, and calculate the total charging load of that side of the service area. ; according to With the rated power of a single charging pile The ratio of these values ​​determines the minimum number of online charging stacks required to handle the current total charging load. ,in ; Let the number of charging piles currently actually in operation be... ; like The total charging load will then be concentrated to On a single charging pile, the total charging load is divided by the rated power of a single charging pile. The integer part of the quotient corresponds to a number of charging piles operating at full power. If the remainder of the division is greater than zero, the remaining load corresponding to the remainder is borne by one charging pile, and the other charging piles are shut down.

[0042] For example, when it is detected that the actual operating power of the first charging pile is less than the rated power and the operating power of the second charging pile is greater than zero (under load), the total charging load of the two charging piles is calculated, and it is determined whether the total load can be fully borne by one of the charging piles and reach the full power operation state. If it is determined that the total load of the two charging piles is sufficient for one of the charging piles to operate at full power, then load consolidation is performed: Control one of the charging piles carrying the total load to output the integrated total power, so that it operates at full power and efficiently; at the same time, control the other charging pile to shut down immediately, exit the operating state, and eliminate light load / no-load losses.

[0043] The above-mentioned method for dynamically integrating the charging load of charging piles concentrates the charging loads that are dispersed across multiple charging piles onto the minimum necessary number of charging piles, enabling as many charging piles as possible to operate at full power, while shutting down unloaded or lightly loaded charging piles in a timely manner. This eliminates the no-load loss and light-load inefficiency problems caused by multiple charging piles operating simultaneously, significantly improving the load rate and operating efficiency of the charging piles and reducing the overall energy consumption of the system.

[0044] This invention also provides a power optimization control system based on SST bidirectional flexible interconnect, such as... Figure 1 As shown, it includes: Solid-state transformers, multiple charging piles, and controllers are respectively configured in the service areas on both sides; The input side of the solid-state transformer is connected to the medium-voltage AC power grid of the corresponding service area, and the output side of the solid-state transformer is connected to the DC bus. The multiple charging piles are connected to the DC bus, and the charging piles are interconnected on the DC side. The controller is configured to execute the power optimization control method based on SST bidirectional flexible interconnect.

[0045] For example, the structure of the two service areas is symmetrical, with each service area equipped with one SST. The input side of the SST is connected to the 10kV medium-voltage AC power grid of the corresponding service area; the output side of the SST is connected to the DC bus of the service area on its side. The SST has a rated capacity of 1MW and its function is to convert 10kV AC power into 800V high-voltage DC power (i.e., input AC10kV, output DC800V).

[0046] Each service area is equipped with a DC 800V bus. The two DC buses are interconnected bidirectionally through a DC tie switch or direct electrical connection, allowing power to flow freely between the two sides.

[0047] Each service area has multiple flexible DC charging piles connected to the DC bus. In a preferred embodiment, four piles are configured on one side, each with a rated power of 480kW; the output end of the charging pile is matched with multiple fast charging terminals (e.g., each charging pile is connected to eight 120kW dual-gun fast charging terminals).

[0048] Among them, multiple charging piles within the same service area are electrically interconnected on the DC side (output side or input side) to achieve capacity sharing among the charging piles; The present invention will be further described in detail below with reference to the accompanying drawings. Taking a dual-sided highway service area as an application scenario, it fully realizes a power optimization control method and system based on SST bidirectional flexible interconnection. Those skilled in the art can refer to and implement it without creative effort, and it completely covers all the technical solutions described in the claims.

[0049] Example 1: Construction of a power optimization control system architecture based on SST bidirectional flexible interconnection Step 1: This embodiment first describes the hardware foundation for implementing power optimization control - a bidirectional interconnected DC architecture with two-sided service areas based on solid-state transformers (SST).

[0050] The power optimization control system includes a first service area subsystem and a second service area subsystem that are structurally symmetrical and bidirectionally interconnected via a DC bus.

[0051] Specifically, the first service area subsystem includes: First solid-state transformer (SST1): The input of SST1 is connected to the 10kV medium-voltage AC power grid of the first service area, and the output of SST1 is connected to the first DC bus. SST1 is configured with a rated capacity of 1MW to convert AC 10kV AC power into DC 800V high-voltage DC power.

[0052] First DC Bus (DC Bus1): The voltage level is DC800V, serving as the power distribution and transmission backbone within the first service area subsystem.

[0053] Multiple Flexible Charging Stacks: In this embodiment, four flexible DC charging stacks with a rated power of 480kW are configured on one side of the service area. The input end of each charging stack is directly connected to the first DC bus. The output side of each charging stack is matched and connected to eight dual-gun DC fast charging terminals with a rated power of 120kW to provide charging services for electric vehicles.

[0054] Flexible charging pile interconnection: The four 480kW flexible charging piles are electrically interconnected on the output side or on the DC side before the charging terminal bus is connected, forming a charging pile group, which enables the sharing and mutual assistance of output power among the charging piles.

[0055] The hardware configuration of the second service area subsystem is exactly the same as that of the first service area subsystem, including the second SST (SST2), the second DC bus (DC Bus2), four 480kW charging piles and corresponding fast charging terminals.

[0056] Bidirectional interconnection: The first DC bus and the second DC bus are electrically connected via a DC tie switch or direct connection, thereby establishing a high-voltage DC (DC 800V) interconnection channel. This channel allows power to flow freely in both directions between the two service area subsystems.

[0057] Key capacity configuration: The total capacity of the charging piles configured in the first service area is [missing information]. The second service area also has a capacity of 1.92MW. The total capacity of the charging piles on both sides is much larger than the rated capacity of a single SST (1MW), and in this embodiment, it is preferably twice the rated capacity of a single SST. This configuration of large charging capacity and small SST capacity is a prerequisite for this system to achieve resource sharing and efficient operation through power optimization.

[0058] The system also includes a controller, which is communicatively connected to SST1, ST2, all flexible charging piles, and the detection unit on the grid side. The controller has an embedded computer program for executing the power optimization control method of this invention. Its core logic is: first, perform global optimization at the SST level, then perform local optimization at the charging pile level.

[0059] Step 2: Before acquiring real-time charging load data from both service areas for power optimization, the controller first executes power supply reliability assurance logic, specifically: Assuming a 10kV power grid failure is detected in the first service area subsystem, the controller will perform the following operations: SST1 in the first service area was shut down and electrically isolated from the de-energized 10kV power grid to prevent power backflow.

[0060] Meanwhile, the SST2 in the second service area serves as a voltage source, maintaining its normal operation. The normally functioning SST2 acts as a voltage source, constructing a stable DC 800V voltage through interconnected DC buses, thereby providing power support for the charging load of the first service area subsystem.

[0061] In this mode, SST2 prioritizes meeting the charging needs of the non-power-loss side (second service area subsystem), while the remaining capacity of SST2 is used to support the charging load of the first service area subsystem on the power-loss side.

[0062] For example, SST1 and SST2 have a rated capacity of 1MW. Assume that before the power outage, the first service area had a charging load of 600kW, and the second service area had a charging load of 400kW. After the first service area loses power, SST2 first meets the 400kW demand of the second service area, and the remaining 600kW capacity is used to support the first service area, fully covering its 600kW demand. If the demand of the first service area exceeds 600kW, the excess capacity is handled by power limiting by the charging stack.

[0063] If it is detected that the 10kV power grids of both service areas are supplying power normally, the system will automatically switch to the SST-level power optimization control mode in step 3.

[0064] Step 3: With normal power supply from the 10kV grid in both service areas, the controller performs power optimization control between the two SST units based on real-time collected charging load data from both service areas. The control strategies under various operating conditions are illustrated below with specific numerical examples.

[0065] Case 1: Charging load in one service area is 0; Operating conditions: The charging load of the first service area is 0kW (i.e., there is no charging demand), and the charging load of the second service area is 300kW (i.e., the total charging demand on this side is 300kW, which is less than the SST rated capacity of 1MW).

[0066] Strategy: The controller shuts down SST1 in the first service area to reduce no-load losses, and all charging load is provided by SST2 in the second service area.

[0067] Case 2: The total charging load in both service areas reaches 40%-50% of the SST's rated capacity; Operating conditions: The charging load in the first service area is 200kW, the charging load in the second service area is 300kW, and the total load on both sides is 500kW. At this time, the rated capacity of a single SST unit is 1MW, and 500kW is exactly 50% of 1MW. The load rate of the first service area is 20%, and the load rate of the second service area is 30%.

[0068] Strategy: The controller optimizes the power to the SST with a higher load rate (i.e., SST2 in the second service area), so that SST2 provides the full 500kW load, making SST2 operate in the optimal load range (i.e., 40%~50% of the rated capacity of SST, corresponding to 400kW~500kW), while shutting down SST1.

[0069] Case 3: The charging power on both sides is greater than 50% of the SST's rated capacity but less than the SST's rated capacity; Operating conditions: The charging load in the first service area is 600kW, and the charging load in the second service area is 700kW. Here, 600kW and 700kW are respectively greater than 50% of the rated capacity of a single SST unit (1MW) (i.e., 500kW), and both are less than the rated capacity of the SST unit (1MW) (i.e., 1000kW). The total load on both sides is 1.3MW (1300kW), which is greater than 500kW.

[0070] Strategy: The two SSTs operate independently, each bearing the charging load of its respective service area.

[0071] Case 4: Charging power in a single service area exceeds the rated capacity of the SST. Operating conditions: The charging load in the first service area is 1.2MW, which exceeds the rated capacity of 1MW of SST1 on this side; the charging load in the second service area is 300kW.

[0072] Strategy: The controller controls SST1 in the first service area to operate at full power (outputting its rated capacity of 1MW). The load power exceeding its rated capacity of 200kW is supplied by SST2 in the second service area through the interconnected DC bus.

[0073] Case 5: Charging power at both service areas exceeds the rated capacity of SST. Operating conditions: The charging load in the first service area is 1.1MW, and the charging load in the second service area is 1.05MW, both of which exceed the rated capacity of 1MW for a single SST unit.

[0074] Strategy: The controller controls both service areas' SSTs to operate at their rated capacity and limits the power of the flexible charging piles on both sides, ensuring that the charging load power of each service area does not exceed 1MW, thus guaranteeing stable full-power operation of the system (the total system power limit is 2MW, which is the sum of the rated capacities of the two SSTs).

[0075] Case 6: Power State of Other Charging Loads For other load conditions other than those mentioned above (e.g., the total load on both sides is greater than 50% of the SST's rated capacity (i.e., 500kW) but has not triggered an overload and is not subject to light load merging conditions), the controller controls the SST in this service area to provide the corresponding charging load demand for this service area, achieving power self-optimization and not performing cross-regional scheduling.

[0076] Step 4, Charge Stack Level Power Optimization Control After the SST-level power optimization control is completed, the controller further performs refined power optimization on the charging pile clusters within the service area on this side, with the goal of reducing the number of charging piles in operation online and reducing no-load losses.

[0077] Example 1: Consolidating multiple charging piles to the minimum required number In this embodiment, four charging piles are configured in a single service area, each with a rated power of [missing information]. The controller executes the following general integration algorithm: Obtain the real-time power of all online charging piles and calculate the total charging load of this service area. (Unit: kW)

[0078] Calculate the minimum number of online charging piles required to support the current total load. If the number of charging piles currently in operation is The total charging load will then be concentrated to On the charging pile, the specific allocation method is as follows: Will Divide by 480, and the integer part of the quotient corresponds to the number of charging piles operating at full power (480kW); if there is a remainder after division, the charging load corresponding to the remainder is handled by one charging pile, and the remaining charging piles are shut down.

[0079] like If the power of each online charging pile is greater than 240kW (i.e. half of the rated power), the current operating state will remain unchanged.

[0080] Example 2: Power integration of two charging piles (Part 1) Initial state: Within the first service area, charging pile 1 is operating at 280kW, charging pile 2 at 200kW, and charging piles 3 and 4 are shut down. Here, 280kW and 200kW are both less than the rated power of the charging piles (480kW).

[0081] Judgment: Neither charging pile 1 nor charging pile 2 is at full power (480kW), and the sum of their power is 480kW, which is exactly equal to the rated power of a single charging pile.

[0082] Execution: The controller performs power optimization, transferring the 200kW load of charging pile 2 to charging pile 1, so that charging pile 1 operates at 480kW (full power), while controlling charging pile 2 to shut down.

[0083] Example 3: Power integration of two charging piles (Part 2) Initial state: Charger pile 1 operates at 350kW, Charger pile 2 operates at 200kW, total load is 550kW, and the rated power of a single charger pile is 480kW.

[0084] Assessment: If the load is integrated into charging pile 1, its power will reach 550kW, exceeding its rated capacity of 480kW, which is not feasible. If integrated into charging pile 2, its power will also reach 550kW, which is also over the limit. Therefore, it is impossible to achieve full-power operation by merging the two piles.

[0085] Execution: The controller maintains the current state, or considers distributing the load across the three charging piles (e.g., charging pile 1 at full power of 480kW, charging pile 2 at 70kW, and charging pile 3 at 0kW). However, based on the principle of prioritizing full-power operation, charging pile 1 is prioritized to operate at full power, with the remaining 70kW handled by charging pile 2, and charging piles 3 and 4 shut down. Compared to the initial state, the number of charging piles operating at full power increases, while the power of charging piles operating under light load decreases, resulting in an overall improvement in efficiency.

[0086] Example 4: Multiple charging piles are operating at more than half power. Initial state: Charger unit 1 is operating at 280kW, Charger unit 2 is operating at 300kW, Charger units 3 and 4 are shut down. Each charger unit has a rated power of 480kW, half of which is 240kW. Both 280kW and 300kW are greater than 240kW.

[0087] Judgment: The power of each online charging pile exceeds half of its rated power (i.e., greater than 240kW).

[0088] Execution: The controller maintains the current power operation and does not perform consolidation. At this time, both stacks have high load rates, and forcibly consolidating them into one would cause that stack to overload, and frequent switching may affect system stability.

[0089] To verify the actual operational efficiency of the power optimization control method based on SST bidirectional flexible interconnection described in this invention, a full-link power loss measurement and statistical analysis was conducted on the charging system of both service areas on highways using this scheme for four consecutive days. The measured data are shown in Table 1 below: Table 1 shows the measured statistics of the continuous operation full-link power loss of the dual-side service area charging system.

[0090] As shown in the above measured data, after adopting the power optimization control method based on SST bidirectional flexible interconnection of the present invention, the comprehensive power loss rate of the two service areas is stably maintained at a low level of 4.25%~5.11%, and the corresponding comprehensive system operating efficiency can reach 94.89%~95.75%. Compared with the traditional operating efficiency of 88%-90%, the present invention optimizes the full-load operation of SST and charging pile, and the power loss rate of the system is greatly reduced. It effectively solves the technical pain points of low efficiency and high power loss of traditional solutions under light load, and fully meets the all-weather, high-reliability charging service needs of highway service areas.

[0091] As can be seen from the above embodiments, the power optimization control method and system based on SST bidirectional flexible interconnect proposed in this invention are as follows: Improved power supply reliability: Enabled automatic switching function of the dual-side power grid, allowing the other side to provide support when one side loses power.

[0092] Improved equipment utilization: solved the tidal phenomenon of uneven charging load on both sides of highway service areas, and realized capacity sharing and mutual assistance.

[0093] Improved system operating efficiency: SST-level light-load merging ensures transformers operate at their optimal efficiency point; power integration at the charging pile level reduces the number of devices operating under no-load conditions. Overall, charging efficiency is improved by 3%-5% compared to traditional AC grid-connected solutions.

[0094] Therefore, this method can be replicated and promoted to highway services, improve the user charging experience, and provide a model construction project for the construction of charging facilities in highway service areas.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A power optimization control method based on SST bidirectional flexible interconnection, characterized in that, include: Based on the constructed bidirectional interconnected DC architecture of the two-sided service areas, charging load data of the two-sided service areas are obtained in real time. Based on the charging load data of both service areas, power optimization control is performed on the SST of both service areas according to the preset strategy. Based on the power optimization control results of the dual-side service area SST, the charging load of the charging pile is dynamically integrated, prioritizing the charging piles in online operation to reach full power operation, and shutting down the charging piles that are unloaded or lightly loaded, thereby realizing the power optimization control of the charging pile. The preset strategies include: When the preset light load conditions are met, the charging load of the SST in one service area is controlled to operate within the preset load range, while the SST in the other service area is shut down. When the charging load of one service area exceeds the rated capacity of the SST, the SST of that service area is controlled to operate at full power, and the load power exceeding its rated capacity is replenished across the region through the SST of the other service area. When the charging load of both service areas exceeds the rated capacity of the SST, the SST in both service areas is controlled to operate at the rated capacity, and the power of the charging pile is limited.

2. The power optimization control method based on SST bidirectional flexible interconnection according to claim 1, characterized in that, The preset load range is 40%-50% of the SST's rated capacity.

3. The power optimization control method based on SST bidirectional flexible interconnection according to claim 1, characterized in that, The preset light load conditions include: the charging load of a single service area is 0; the total charging load of both service areas is less than or equal to 50% of the rated capacity of a single SST unit.

4. The power optimization control method based on SST bidirectional flexible interconnection according to claim 1, characterized in that, Before acquiring real-time charging load data from both service areas, the process also includes: Real-time monitoring of the power supply status of the medium-voltage AC power grid in both service areas; If a power grid failure is detected in only one service area, the SST in the service area on the side with the power failure will be shut down and isolated from the power grid. The SST in the other service area, which is operating normally, will be used as a voltage source to build a DC bus to provide power support for the charging load of the service area on the side with the power failure. If it is detected that the power grids of both service areas are supplying power normally, the SST power optimization control mode of both service areas will be executed.

5. The power optimization control method based on SST bidirectional flexible interconnection according to claim 1, characterized in that, The dynamic integration of the charging load of the charging pile specifically includes: Obtain the real-time operating power of all online charging piles in one side of the service area, and calculate the total charging load of that side of the service area; Based on the ratio of the total charging load to the rated power of a single charging pile, determine the minimum number of charging piles required to carry the current total load. ; If the number of charging piles currently actually in operation is greater than Then, the integration operation will be performed, including: Concentrate the current total charging load to On the charging pile, to make it operational Once one charging stack reaches full power operation, it controls the other charging stacks to shut down. If the number of charging piles currently operating online is equal to If the real-time operating power of each charging pile exceeds half of its rated power, the current operating state will remain unchanged.

6. The power optimization control method based on SST bidirectional flexible interconnection according to claim 5, characterized in that, Concentrate the current total charging load to On the charging pile, to make it operational The charging pile has reached full power operation, specifically: Divide the total charging load by the rated power of a single charging pile. The integer part of the quotient corresponds to the number of charging piles operating at full power. If the remainder of the division is greater than zero, the charging load corresponding to the remainder is handled by one charging pile, and the remaining charging piles are shut down.

7. The power optimization control method based on SST bidirectional flexible interconnection according to claim 1, characterized in that, The bidirectional interconnected DC architecture for the dual-side service areas specifically includes: SSTs are configured in both service areas. The input side of each SST is connected to the medium-voltage AC power grid of both service areas, and the output side of the SSTs is connected to the DC bus. Multiple charging piles are connected to the DC bus, and the charging piles are interconnected on the DC side. Among them, the total capacity of the charging piles configured in a single service area is greater than the rated capacity of a single SST.

8. The power optimization control method based on SST bidirectional flexible interconnection according to claim 7, characterized in that, The total capacity of the charging piles configured in the single-sided service area is twice the rated capacity of the single-sided SST.

9. A power optimization control system based on SST bidirectional flexible interconnection, characterized in that, include: Solid-state transformers, multiple charging piles, and controllers are respectively configured in the service areas on both sides; The input side of the solid-state transformer is connected to the medium-voltage AC power grid of the corresponding service area, and the output side of the solid-state transformer is connected to the DC bus. The multiple charging piles are connected to the DC bus, and the charging piles are interconnected on the DC side. The controller is configured to perform the power optimization control method based on SST bidirectional flexible interconnect as described in any one of claims 1 to 8.

10. The power optimization control system based on SST bidirectional flexible interconnection according to claim 9, characterized in that, The solid-state transformer is configured with a capacity of 1MW, an input of AC10kV, and an output of DC800V.

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