A multi-ac-dc charging pile group control system and a charging pile flexible load group control method

Abstract

The application discloses a multi-AC / DC charging pile group control system and a charging pile flexible load group control method, wherein the system comprises a master control layer, a field sub-control layer and a device layer connected in sequence; the master control layer comprises a transformer of a transformer area, which is used for converting external power into a stable voltage suitable for the current transformer area; the field sub-control layer comprises a charging station flexible load group control module and a charging pile management module; the flexible load group control module is connected with the master control layer and the device layer, is used for acquiring transformer power parameters and self-configuration data fed back by the master control layer, and regulates and controls charging power based on a preset flexible load group control algorithm; the charging pile management module is connected with the flexible load group control module and the device layer, and is used for completing permission of starting and stopping of the charging pile, issuing of a charging model and tracking of a charging process; and the device layer comprises a plurality of DC or AC charging piles. The application can improve the regulation and control capability of the power load safety of the charging station, and realizes response of load resources of different charging piles to power grid demand.

Description

Technical Field

[0001] This invention relates to the field of charging pile power control technology, and in particular to a multi-AC / DC charging pile group control system and a flexible load group control method for charging piles. Background Technology

[0002] Charging stations are a crucial means of replenishing energy for new energy passenger vehicles, widely distributed in commercial parking lots, residential parking areas, highway service areas, bus stops, factory areas, and other locations. Charging piles typically include AC and DC piles of varying power levels to meet different charging speeds and power requirements. AC piles typically have a charging power between 3.3 and 22 kW, while DC piles typically have a charging power between 15 and 320 kW. With the increasing prevalence of public charging piles and stations, electricity load growth often outpaces the pace of grid upgrades, significantly increasing grid load pressure. Simultaneously, because the timing and number of users connecting to charging piles are random, and because battery technology advancements have increased available charging voltage and power, grid load volatility is growing. Therefore, effectively regulating the load on charging piles has become a necessary challenge to ensure the safe and stable operation of the power grid.

[0003] Currently, the common method for regulating charging pile load is peak-valley charging pricing. This method guides user behavior through price differences, encouraging users to charge during low-load periods, effectively achieving peak shaving and valley filling. However, this method is indirect, failing to accurately regulate the size of the electricity load or completely eliminate the randomness of load fluctuations. Flexible load control for charging piles is another more effective charging load control technology chosen by charging pile manufacturers and power companies. By limiting the charging power of charging piles in a timed or quantitative manner, it achieves power coordination between the load and the power grid. However, current research on flexible load control for charging piles still has two problems: 1. Lack of consideration for coordinated group control of charging piles. Flexible load control of charging piles should not only consider its own power but also the power coordination with other charging piles in the station, as well as the differences in the SOC (State of Charge) values ​​of batteries connected to different piles. For charging users, the lower the SOC value, the more urgent the charging demand; conversely, when the SOC is high, even if the charging power is limited, user dissatisfaction will not be too high. At the same time, different piles connected to different BMS systems will have different available charging power. Currently, coordination between different charging piles mainly relies on the charging pile operation management platform. There is insufficient direct coordination between individual piles. If the operation management platform and the piles communicate remotely wirelessly, then control response speed is also a potential issue. 2. There is a lack of coordination among various charging pile load-ordering adjustment commands. Orderly charging includes commands such as transformer load rate capacity safety at the charging station area, remote scheduling of virtual power plants, intelligent microgrid scheduling of power generation, grid, load, and storage, and V2G reverse energy replenishment scheduling. These commands may arrive individually or simultaneously, requiring the charging station control platform to quickly determine the legality of each command and select which to execute.

[0004] Therefore, it is necessary to propose a multi-AC / DC charging pile group control system and a flexible load group control method for charging piles, which can improve the power load safety regulation capability of charging stations and realize the coordinated response of load resources of different charging piles to the grid demand. Summary of the Invention

[0005] In view of this, the present invention provides a multi-AC / DC charging pile group control system and a charging pile flexible load group control method to solve the technical problems of the current charging pile flexible load control, which lacks consideration for the coordinated group control of charging piles and lacks the coordination of multiple charging pile load orderly charging adjustment commands, resulting in poor power load safety regulation capability of charging stations and failure to meet existing usage requirements.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a multi-AC / DC charging pile group control system, comprising a main control layer, a field sub-control layer and an equipment layer connected in sequence;

[0008] The main control layer includes the distribution transformer, which is used to convert external power into a stable voltage suitable for the current distribution area.

[0009] The on-site sub-control layer includes a charging station flexible load group control module and a charging pile management module. The flexible load group control module is connected to the main control layer and the equipment layer. It is used to obtain the transformer power parameters and its own configuration data fed back by the main control layer, and to regulate the charging power based on the preset flexible load group control algorithm. The charging pile management module is connected to the flexible load group control module and the equipment layer. It is used to complete the permission for starting and stopping the charging pile, the issuance of the billing model, and the tracking of the charging process.

[0010] The equipment layer includes multiple DC or AC charging piles, each with corresponding performance parameters, which charge the vehicles under the control of the charging pile management module.

[0011] Furthermore, the main control layer also includes a virtual power plant and a smart microgrid strategy machine;

[0012] The virtual power plant is used for the aggregation of distributed energy resources and power dispatch.

[0013] The intelligent microgrid strategy unit is used to integrate local energy and provide voltage input to the current transformer area;

[0014] The flexible load group control module is also used to acquire power data from the virtual power plant and the smart microgrid strategy machine, and to regulate the charging power in conjunction with the transformer substation and the preset flexible load group control algorithm.

[0015] Secondly, the present invention also provides a flexible load group control method for charging piles, applied to the multi-AC / DC charging pile group control system described in the above technical solution, comprising:

[0016] Obtain configuration and operational data from the device layer and the main control layer;

[0017] The total real-time charging power of the charging piles is calculated based on the operating data of the equipment layer. Based on the total real-time charging power of the charging piles, the configuration data of the field sub-control layer, and the configuration and operating data of the main control layer, the power setpoint of the entire station is determined.

[0018] Based on the overall station power setting value, equipment layer configuration data and operation data, the output power of each charging pile in the equipment layer is allocated to form a power allocation command;

[0019] The power allocation command is sent to the device layer, and the real-time operating power of each charging pile is obtained in real time. The execution error is calculated based on the real-time operating power and the power setting value of the whole station, and the execution error is uploaded to the main control layer.

[0020] Furthermore, the configuration data of the main control layer includes: the upper limit of transformer power capacity; the operation data of the main control layer includes: the real-time measured power of the transformer;

[0021] The configuration data of the device layer includes: the number of each pile, the type of each pile, the rated power of each pile, and the upper and lower limits of the charging power; the operation data of the device layer includes: the battery connection status of each pile, the real-time charging power of each pile, the power requirement read by the BMS, and the real-time data of the BMS.

[0022] The configuration data of the field control layer includes: control time interval, power regulation margin, power upper limit control coefficient, and power allocation formula coefficient matrix.

[0023] Furthermore, the determination of the total station power setpoint based on the real-time total charging power of the charging piles, the configuration data of the on-site sub-control layer, and the configuration and operation data of the main control layer includes:

[0024] The overload monitoring formula is used to determine whether the transformer is overloaded; the overload monitoring formula is as follows:

[0025] Pe>P0×(1-ep),

[0026] Where ep represents the power regulation margin, P0 represents the upper limit of the transformer power capacity, and Pe represents the actual measured power of the transformer;

[0027] If the overload monitoring formula holds true, then the formula for calculating the total station power setpoint Pset is:

[0028] Pset=K×(P-(Pe-P0+ep×P0)),

[0029] Where K represents the power upper limit control coefficient, and P represents the total real-time charging power;

[0030] If the overload monitoring formula does not hold, then the total station power setpoint Pset is set to the upper limit of transformer power capacity P0.

[0031] Furthermore, when the main control layer includes a virtual power plant and a smart microgrid strategy unit, the step of determining the total station power setpoint based on the real-time total charging power of the charging piles, the configuration data of the field sub-control layer, and the configuration and operation data of the main control layer also includes:

[0032] Determine whether the current moment is within the power command time range, and based on the determination result, determine the intermediate power variable to be executed, expressed by the formula:

[0033]

[0034] Where Pnew represents the intermediate power variable; tv0~tv1 represents the instruction time period of the virtual power plant; tx0~tx1 represents the instruction time period of the smart microgrid strategy machine;

[0035] Determine whether to execute the power intermediate variable based on the relationship between the current real-time total charging power P and the power intermediate variable Pnew;

[0036] If Pnew = Pv and P > Pnew × (1 - ep), then the intermediate power variable is executed.

[0037] If Pnew = Px, and P > Pnew × (1 + ep) or P < Pnew × (1 - ep) holds true, then the validity of the power command is judged, and the formula for judging validity is:

[0038]

[0039] Where Pup_i represents the upper limit of charging power, Pdn_i represents the lower limit of charging power, and n represents the total number of charging piles;

[0040] If the validity judgment formula is not met, the power command response will not be executed and an alarm will be triggered; if the validity judgment formula is met, the power command response will be executed and the power setting value Pset = Pnew for the entire station will be updated.

[0041] Furthermore, the process of allocating the output power of each charging pile in the equipment layer based on the overall station power setting, equipment layer configuration data, and operational data to form a power allocation instruction includes:

[0042] Calculate the SOC weighting coefficient based on real-time data from the BMS;

[0043] Calculate the power weighting coefficient based on the power upper limit control coefficient and the power allocation formula coefficient matrix;

[0044] Based on the SOC weighting coefficient, power weighting coefficient, and total station power setting, calculate the power distribution for each pile;

[0045] The legality of the power allocation for each pile is judged, the output power of each pile is determined based on the judgment result, and a power allocation instruction is generated.

[0046] Furthermore, the formula for calculating the SOC weighting coefficient based on the real-time data of the BMS is as follows:

[0047]

[0048] Where ln is a logarithmic function; SOC_i is the real-time data of BMS, and w_SOC_i is the SOC weight coefficient.

[0049] Furthermore, based on the SOC weighting coefficient, power weighting coefficient, and total station power setpoint, the power distribution for each pile is calculated, including:

[0050] The power distribution formula for each pile is as follows:

[0051]

[0052] Where Pset_i represents the current pile power allocation value, w_P_i represents the power weight coefficient, and w_SOC_i represents the SOC weight coefficient.

[0053] Furthermore, the legality of the power allocation for each pile is determined, and the output power of each pile is determined based on the determination result, including:

[0054] The formula for determining legality is:

[0055] if Pset_i≥Pdn_i and Pset_i≤Pup_i,

[0056] Where Pset_i represents the current pile power allocation value;

[0057] If the validity judgment formula is not met, then the remaining charging piles are obtained. The remaining charging piles include j piles whose current power allocation value is lower than Pdn_j, and k piles whose current power allocation value is higher than Pup_i. The power of the remaining charging piles is reset, and the power reset formula is:

[0058]

[0059] Calculate the remaining allocated power:

[0060]

[0061] The remaining allocated power of the charging piles is recalculated based on the remaining allocated power and the allocated power formula. The legality of the remaining charging piles after the power redistribution is judged again until the power of all charging piles is legal, and the output power of each pile is obtained.

[0062] Furthermore, the method also includes: a power regulation process constrained power oscillation method, which smooths the new and old power commands when the power changes at high frequencies by introducing an inter-constant, including:

[0063] Formula for smoothing changes in power command for a single pile:

[0064]

[0065] in:

[0066] Where τ is the time constant in seconds; the larger τ is, the slower the power response speed of the charging pile group, but the smoother the power change of a single pile; the smaller τ is, the faster the power response speed of the charging pile group, but the greater the power change of a single pile; Pset_target is the new power command, Pset_old is the old power command, and △Pset_ref is the critical change value of the power command. When |Pset_target-Pset_old|≥△Pset_ref, the formula for smoothing the change of power command of a single pile is triggered.

[0067] Compared with existing technologies, the multi-AC / DC charging pile group control system and flexible load group control method for charging piles proposed in this invention have the following advantages:

[0068] 1. Coordinate multiple different types of charging piles; fully consider the common types of charging piles, communication protocols, and communication interfaces on the market, so that the hardware medium is widely applicable to various AC and DC charging piles with low-voltage AC bus voltage; realize the coordinated control of multiple piles by one hardware medium, reduce investment costs, and improve the unified coordinated control capability of different types of charging piles.

[0069] 2. Power safety of charging stations based on group control and rapid response; the hardware medium is installed on-site and can directly control the charging piles independently of the charging pile management platform, making the charging pile status monitoring more timely and the response to overload faster; power limits are distributed to multiple charging piles to avoid the power of individual piles being too affected.

[0070] 3. Balancing the flexible load adjustment potential of charging piles and the satisfaction of charging users: The power allocation algorithm fully considers the charging capabilities of different vehicle models and the SOC of the connected charging piles, so that users with low SOC can be allocated more charging power, and balances the charging satisfaction of different charging users when the charging power is limited. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of the structure of the multi-AC / DC charging pile group control system provided by the present invention;

[0072] Figure 2 This is a field wiring diagram of the multi-AC / DC charging pile group control system provided by the present invention;

[0073] Figure 3 This is a communication information diagram of the multi-AC / DC charging pile group control system provided by the present invention;

[0074] Figure 4 This is a flowchart illustrating the method for setting the power setting value for the entire station.

[0075] Figure 5 This is a diagram illustrating the SOC weighting coefficients;

[0076] Figure 6 This is a schematic diagram of the power allocation process for each charging station;

[0077] Figure 7 This is a schematic diagram of the status of each charging pile, the BMS access status, and the power command matrix constructed through simulation;

[0078] Figure 8 This is a comparison chart of the total charging power before and after the flexible load group control of the charging station;

[0079] Figure 9 This is a comparison chart of the charging power of different charging piles within the power command execution range;

[0080] Figure 10 This is a graph showing the time delays caused by power capacity safety and power command response after each pile is connected to different initial SOCs.

[0081] Figure 11 This is a comparison chart of charging power of charging piles after introducing power fluctuation smoothing during the power command execution process. Detailed Implementation

[0082] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0083] Example 1

[0084] Please see Figure 1 This embodiment provides a multi-AC / DC charging pile group control system 100, including a main control layer 101, a field sub-control layer 102 and an equipment layer 103 connected in sequence;

[0085] The main control layer 101 includes a transformer for converting external power into a stable voltage suitable for the current use of the transformer area;

[0086] The on-site sub-control layer 102 includes a charging station flexible load group control module and a charging pile management module; the flexible load group control module is connected to the main control layer and the equipment layer and is used to monitor and regulate the charging power; the charging pile management module is used for permitting the start and stop of charging piles, issuing billing models, and tracking the charging process.

[0087] The equipment layer 103 includes multiple DC or AC charging piles, each with corresponding performance parameters, and charges the vehicle under the control of the charging pile management module.

[0088] The AC / DC charging pile group control system provided in this embodiment, through the connection of the flexible load group control module with the main control layer and equipment layer, enables the system to monitor and adjust the charging power in real time. It can flexibly adjust the power output of the charging piles based on factors such as grid load, charging pile usage status, and charging demand, avoiding grid overload, optimizing resource utilization, and ensuring the stability of power supply. The charging pile management module provides functions such as starting and stopping permits for charging piles, issuing billing models, and tracking the charging process, improving the level of centralized and automated management. Through centralized control and monitoring, operators can perform equipment maintenance, status monitoring, and fault diagnosis more efficiently, reducing labor costs. This system can simultaneously support DC and AC charging piles, providing greater flexibility to adapt to the charging needs of different types of electric vehicles. Whether it's a small private car or a large-capacity vehicle, effective charging services can be obtained in different charging environments. Through the charging pile management module, the system can track the charging process in real time, ensuring smooth charging completion, while automatically billing and settling accounts. Users can obtain convenient services when using charging piles, reducing waiting time and improving charging efficiency.

[0089] As a specific implementation, the charging station flexible load group control module connects to each charging pile in the charging station through a multi-charging pile communication connection interface. The external communication interfaces include RS485, Ethernet, fiber optic, and wireless 4G to ensure that the system can adapt to different charging station scenarios.

[0090] In one specific embodiment, the charging station flexible load group control module and the charging pile management module manage the charging piles in parallel. The charging pile management platform is mainly responsible for authorizing the start and stop of charging piles, issuing billing models, and tracking the charging process. In some embodiments, the charging station flexible load group control module is also equipped with a local or cloud-based display to present the monitoring results of the charging power of each pile and to configure parameters.

[0091] As a preferred embodiment, such as Figure 2 As shown, the main control layer also includes a virtual power plant and a smart microgrid strategy machine;

[0092] The virtual power plant is used for the aggregation of distributed energy resources and power dispatch.

[0093] The intelligent microgrid strategy unit is used to integrate local energy and provide voltage input to the current transformer area;

[0094] The flexible load group control module is also used to acquire power data from the virtual power plant and the smart microgrid strategy machine, and to regulate the charging power in conjunction with the transformer substation and the preset flexible load group control algorithm.

[0095] Based on the above multi-factor instructions, the upper limit or target charging power of the entire charging pile group within a certain time period is generated; when the real-time available charging power of the transformer is greater than the virtual power plant or smart microgrid dispatch instructions, the virtual power plant or microgrid dispatch instructions are executed; otherwise, the power capacity limit instructions of the transformer are executed; when the virtual power plant instructions and smart microgrid dispatch instructions exist at the same time, the execution priority of the virtual power plant instructions is higher.

[0096] This invention solves the problem of decision-making failure in scenarios with conflicting multiple instructions, and satisfies the requirements of safe operation of charging pile groups and economical load scheduling to ensure the execution of corresponding instructions.

[0097] In practical applications, the flexible load group control module must be connected to the distribution transformer, and in some cases, it may be selectively connected to the virtual power plant (VPP) and the smart microgrid strategy controller. The virtual power plant (VPP) and the smart microgrid strategy controller are used to issue power commands.

[0098] like Figure 3 As shown, Figure 3 A schematic diagram of the communication information of a multi-AC / DC charging pile group control system is shown.

[0099] Example 2

[0100] This invention provides a flexible load group control method for charging piles, applied to the flexible load group control module of the multi-AC / DC charging pile group control system described in Embodiment 1, comprising:

[0101] Obtain configuration and operational data from the device layer and the main control layer;

[0102] The total real-time charging power of the charging piles is calculated based on the operating data of the equipment layer. Based on the total real-time charging power of the charging piles, the configuration data of the field sub-control layer, and the configuration and operating data of the main control layer, the power setpoint of the entire station is determined.

[0103] Based on the overall station power setting value, equipment layer configuration data and operation data, the output power of each charging pile in the equipment layer is allocated to form a power allocation command;

[0104] The power allocation command is sent to the device layer, and the real-time operating power of each charging pile is obtained in real time. The execution error is calculated based on the real-time operating power and the power setting value of the whole station, and the execution error is uploaded to the main control layer.

[0105] In a preferred embodiment, the configuration data of the main control layer includes: the upper limit of transformer power capacity P0; the operation data of the main control layer includes: the real-time measured power Pe of the transformer;

[0106] The configuration data of the device layer includes: the numbers of each pile, the types of each pile (DC pile / AC pile), the rated power charging power Pr_i of each pile, as well as the upper limit Pup_i and the lower limit Pdn_i of the charging power; the operation data of the device layer includes: the states of each pile connected to the battery, the real-time charging power P_i of each pile, the read power demand Pask_i of the BMS, and the real-time data SOC_i of the BMS;

[0107] It should be noted here that in the charging pile communication protocol, Pask_i and SOC_i are not necessary, and there are cases of data defaults; at this time, the values of these two variables are assigned according to the following formulas:

[0108] Pask_i = P_i when the charging pile cannot upload Pask_i data

[0109] SOC_i = 0 when the charging pile cannot upload SOC_i data,

[0110] The configuration data of the on-site sub-control layer includes: the control time interval δt (for example: 10s), the power regulation margin ep (for example: 3%), the power upper limit regulation coefficient K (for example: 98%), and the power distribution formula coefficient matrix w (form: [wPr, wP, wPask]).

[0111] As a specific embodiment, the calculation formula for the total real-time charging power of the charging piles is:

[0112]

[0113] where i is the number of each pile and n is the total number of charging piles.

[0114] If the transformer only bears the load of the charging piles, then P = Pe always holds. If the transformer bears other loads, then P < Pe; Pe is the real-time measured power of the transformer.

[0115] As a preferred embodiment, determining the全站功率设定值 (total station power setting value) based on the total real-time charging power of the charging piles, the configuration data of the on-site sub-control layer, as well as the configuration data and operation data of the main control layer, includes:

[0116] Judging whether the transformer is overloaded by judging whether the overload monitoring formula holds; the overload monitoring formula is:

[0117] Pe > P0 × (1 - ep),

[0118] where ep represents the power regulation margin, P0 represents the upper limit of the transformer power capacity, and Pe represents the measured power of the transformer;

[0119] If the overload monitoring formula holds, the calculation formula for the total station power setting value Pset is:

[0120] Pset=K×(P-(Pe-P0+ep×P0)),

[0121] Where K represents the power upper limit control coefficient, and P represents the total real-time charging power;

[0122] If the overload monitoring formula does not hold, then the total station power setpoint Pset is set to the upper limit of transformer power capacity P0.

[0123] This formula reflects the principle of orderly power transfer from the charging pile group to other electrical loads of the transformer.

[0124] The purpose of the above method is to allow the charging station load to supply power to other electrical loads on the transformer.

[0125] In a preferred embodiment, when the main control layer includes a virtual power plant and a smart microgrid strategy unit, the step of determining the total station power setpoint based on the real-time total charging power of the charging piles, the configuration data of the field sub-control layer, and the configuration and operation data of the main control layer further includes:

[0126] Determine whether the current moment is within the power command time range, and based on the determination result, determine the intermediate power variable to be executed, expressed by the formula:

[0127]

[0128] Where Pnew represents the intermediate power variable; tv0~tv1 represents the instruction time period of the virtual power plant; tx0~tx1 represents the instruction time period of the smart microgrid strategy machine;

[0129] Determine whether to execute the power intermediate variable based on the relationship between the current real-time total charging power P and the power intermediate variable Pnew;

[0130] If Pnew = Pv and P > Pnew × (1 - ep), then the intermediate power variable is executed.

[0131] If Pnew = Px, and P > Pnew × (1 + ep) or P < Pnew × (1 - ep) holds true, then the validity of the power command is judged, and the formula for judging validity is:

[0132]

[0133] Where Pup_i represents the upper limit of charging power, Pdn_i represents the lower limit of charging power, and n represents the total number of charging piles;

[0134] If the validity judgment formula is not met, the power command response will not be executed and an alarm will be triggered; if the validity judgment formula is met, the power command response will be executed and the power setting value Pset = Pnew for the entire station will be updated.

[0135] like Figure 4 As shown, Figure 4 A schematic diagram illustrating the process of setting the power setting value for the entire station is shown.

[0136] In a preferred embodiment, the step of allocating the output power of each charging pile in the equipment layer according to the overall station power setting value, equipment layer configuration data, and operation data to form a power allocation instruction includes:

[0137] Calculate the SOC weighting coefficient based on real-time data from the BMS;

[0138] Calculate the power weighting coefficient based on the power upper limit control coefficient and the power allocation formula coefficient matrix;

[0139] Based on the SOC weighting coefficient, power weighting coefficient, and total station power setting, calculate the power distribution for each pile;

[0140] The legality of the power allocation for each pile is judged, the output power of each pile is determined based on the judgment result, and a power allocation instruction is generated.

[0141] As a specific example, the formula for calculating the SOC weighting coefficient w_SOC_i is:

[0142]

[0143] Here, ln is a logarithmic function; this formula ensures that the higher the SOC of the battery, the lower the SOC weight coefficient. When the power of the entire charging station is limited, it allows charging users with low SOC to be allocated more charging power, thus balancing the overall dissatisfaction of different charging users. At the same time, using a logarithmic function can alleviate the gradient difference of SOC weight coefficients under different SOCs, avoiding a sharp drop in charging power as SOC increases. 101% and 1% are parameters used for error prevention, avoiding abrupt changes in the power gradient when SOC_i is close to 0% and close to 100%.

[0144] Based on the SOC_i calculation of the SOC weight coefficient, this invention innovatively proposes a flexible formula for the SOC weight coefficient. Verification has shown that this formula can reduce the problem of sudden changes in SOC gradient and prevent the charging power from rapidly declining as SOC increases; it also achieves a balance between flexible changes in the charging process and the user's demand for charging time.

[0145] like Figure 5 As shown, Figure 5 The distribution pattern of the SOC weight coefficient is shown; it can be seen that the weight coefficient ranges from 1 to 10, which satisfies the requirement of giving higher weight to users with low SOC without causing too large gradient changes; as the charging process proceeds, the change of the weight allocation coefficient during the increase of SOC is relatively "flexible", which confirms the setting of flexible load adjustment.

[0146] In a preferred embodiment, the power weighting coefficient is calculated based on the power upper limit control coefficient and the power allocation formula coefficient matrix, including:

[0147] w_P_i=wPr×Pr_i+wP×P_i+wPask×Pask_i,

[0148] Where [wPr,wP,wPask] represents the power allocation formula coefficient matrix, which is configured according to user needs, and wPr+wP+wPask>0; Pr_i represents the rated charging power of each charging pile; P_i represents the real-time charging power of each charging pile; and Pask_i represents the power requirement read by the BMS.

[0149] In practice, wPask is taken into account because the required power is a relatively balanced power that can be received by both the charging pile and the battery after communication between the BMS and the charging pile. It does not change at any time and will not exhaust the charging potential of the charging pile.

[0150] As a preferred embodiment, the power allocation for each pile is calculated based on the SOC weighting coefficient, the power weighting coefficient, and the total station power setting value, including:

[0151] The power distribution formula for each pile is as follows:

[0152]

[0153] Where Pset_i represents the current pile power allocation value, w_P_i represents the power weight coefficient, and w_SOC_i represents the SOC weight coefficient.

[0154] In a preferred embodiment, the legality of the allocated power of each pile is determined, and the output power of each pile is determined based on the determination result, including:

[0155] The formula for determining legality is:

[0156] if Pset_i≥Pdn_i and Pset_i≤Pup_i,

[0157] Where Pset_i represents the current pile power allocation value;

[0158] If the validity judgment formula is not met, then the remaining charging piles are obtained. The remaining charging piles include j piles whose current power allocation value is lower than Pdn_j, and k piles whose current power allocation value is higher than Pup_i. The power of the remaining charging piles is reset, and the power reset formula is:

[0159]

[0160] Calculate the remaining allocated power:

[0161]

[0162] The remaining allocated power of the charging piles is recalculated based on the remaining allocated power and the allocated power formula. The legality of the remaining charging piles after the power redistribution is judged again until the power of all charging piles is legal, and the output power of each pile is obtained.

[0163] This iterative redistribution can achieve global convergence, which is an important way to increase the robustness of the algorithm. This invention innovatively transforms the control error into an active operation and maintenance action, and realizes the control error in advance at all times, forming a closed-loop control logic of error feedback.

[0164] After the flexible load group control module issues power commands to each charging pile, it also needs to monitor and calculate the power in real time and provide feedback on the execution error. The formula is as follows:

[0165]

[0166] Perror represents the real-time execution error, which is fed back to the main control layer device.

[0167] The system iterates repeatedly to ensure that the power allocation settings for all charging stations are valid, and then distributes and provides feedback on the execution results.

[0168] When a charging station executes a power command, sudden changes in the power command may cause the charging power to oscillate back and forth, or the power to change too quickly, posing a risk of battery damage. As a preferred embodiment, a critical change value ΔPset_ref for the power command needs to be set. When the absolute value of the change between the new power command Pset_target and the old power Pset_old, |Pset_target - Pset_old| ≥ ΔPset_ref, the single-station power change smoothing formula is triggered, as follows:

[0169]

[0170] in:

[0171] Where τ is the time constant, in seconds; the larger τ is, the slower the power response speed of the charging pile group, but the smoother the power change of a single pile; the smaller τ is, the faster the power response speed of the charging pile group, but the larger the power change of a single pile. Considering that a 1-second time constant can lead to a time delay of Δt ≥ 9 seconds, this is sufficient for the millisecond-level response speed of the power grid; the setting of ΔPset_ref should take into account the charging pile's ability to withstand power fluctuations. Charging piles with high rated power have more complete overload protection, short-circuit protection, and other devices; when the rated power of the charging pile is less than 100kW, it is recommended that the change rate be 60kW / min, i.e., 1kW / s, to reduce the risk of impact or charging interruption caused by excessive power fluctuations.

[0172] like Figure 6 As shown, Figure 6 The power allocation process for each charging station was demonstrated.

[0173] As a specific embodiment, to verify the effectiveness of the method of this invention, we constructed a charging pile group control simulation platform based on MATLAB, and constructed the charging pile operation function (derived from the measured operation function), the BMS operation function, and the station charging process flow program; please refer to... Figure 7 The control algorithm of this invention is encapsulated into a control function, and the control effect is simulated. The charging pile status and BMS access process are shown in the figure. The simulation conditions of the charging station with 18 DC piles, its rated power, BMS access time, and initial access state are listed. The power command matrix is ​​given, which conforms to the power command structure described in this invention. The simulated charging station has not yet undergone capacity expansion, and the upper limit of the transformer capacity is still at a relatively low 450kW.

[0174] Please see Figure 8 , Figure 8 The simulation demonstrates the overall charging power trend of the charging station. Under no restrictions, the peak charging power of the charging station exceeds 600kW. When the power capacity is controlled, the maximum charging power of the station is suppressed to around 450kW. After the power command response is executed, the total charging power in different time periods will be further restricted. When flexible load control is executed, the charging power of each pile will oscillate to a certain extent, so the time interval (set to 10s in this simulation) should not be too short. In addition, the limitation of peak power will lead to further transfer of charging load, so the orderly adjustment of charging load requires comprehensive economic value research in the future.

[0175] Please see Figure 9 , Figure 9The simulation shows the charging power changes of charging piles 9, 16, and 18 in a charging station, and the corresponding SOC changes of the charging batteries during a power output of Px = 350kW. It can be seen that when pile 9 is first connected, the initial power increase phase (the charging power increase of the charging pile is not instantaneous, but is used to protect the battery) is relatively slow. Pile 18, because its connected battery has a higher SOC, quickly reduces the charging power. Although the SOC of pile 9 is lower than that of pile 18, because pile 18 has a higher rated power and provides a higher power demand, the charging power of pile 18 is higher than that of pile 9.

[0176] Please see Figure 10 The charging time extended for each charging station due to power capacity safety and power command response is generally 20% shorter for charging stations with an initial SOC ≤ 20% compared to those with an SOC > 20%. Specifically, charging stations 4, 14, and 17, which have shorter delays, all have lower initial SOC levels. However, this is not absolute; for example, charging stations 6 and 16 have longer delays, which are related to the SOC connection time and the triggering time of the power command. It is evident that there is still room for further optimization in the charging power allocation algorithm.

[0177] Please see Figure 11 Distinguished from Figure 9 The band width exhibited by the medium power output is caused by the power oscillation when the single-pile power change smoothing formula is not enabled. Enabling the power smoothing formula does not affect the overall accuracy of the power response, but reduces power value oscillation, the band width basically disappears, and the flexibility of power change transitions increases, which is beneficial to the health of battery charging.

[0178] This invention provides a multi-AC / DC charging pile group control system and a flexible load group control method for charging piles. The system clearly defines the hardware medium wiring topology, the structure for acquiring data from the main control layer and the equipment layer, and designs the flexible load group control process in detail. The method divides the flexible load control process into two parts: power capacity safety and power quality response, and designs a complete process for power command judgment, allocation, and response execution. This invention not only improves the power load safety regulation capability of charging stations but also realizes the coordinated response of load resources from different charging piles to grid demands, demonstrating high practical value.

[0179] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-AC / DC charging pile group control system, characterized in that, This includes the main control layer, the field control layer, and the equipment layer, which are connected in sequence. The main control layer includes the distribution transformer, which is used to convert external power into a stable voltage suitable for the current distribution area. The on-site control layer includes a flexible load group control module for charging stations and a charging pile management module; The flexible load group control module is connected to the main control layer and the equipment layer. It is used to obtain the transformer power parameters and its own configuration data fed back by the main control layer, and to regulate the charging power based on the preset flexible load group control algorithm. The charging pile management module is connected to the flexible load group control module and the equipment layer. It is used to complete the permission for starting and stopping the charging pile, the issuance of the billing model, and the tracking of the charging process. The equipment layer includes multiple DC or AC charging piles, each with corresponding performance parameters, which charge the vehicle under the control of the charging pile management module. The flexible load group control module is specifically used for: Obtain configuration and operational data from the device layer and the main control layer; The total real-time charging power of the charging piles is calculated based on the operating data of the equipment layer. Based on the total real-time charging power of the charging piles, the configuration data of the field sub-control layer, and the configuration and operating data of the main control layer, the power setpoint of the entire station is determined. Based on the overall station power setting value, equipment layer configuration data and operation data, the output power of each charging pile in the equipment layer is allocated to form a power allocation command; The power allocation command is sent to the device layer, and the real-time operating power of each charging pile is obtained in real time. The execution error is calculated based on the real-time operating power and the power setting value of the whole station, and the execution error is uploaded to the main control layer. The process involves allocating the output power of each charging pile in the equipment layer based on the overall station power setting, equipment layer configuration data, and operational data, thereby generating a power allocation instruction, including: Calculate the SOC weighting coefficient based on real-time data from the BMS; Calculate the power weighting coefficient based on the power upper limit control coefficient and the power allocation formula coefficient matrix; Based on the SOC weighting coefficient, power weighting coefficient, and total station power setting, calculate the power distribution for each pile; The legality of the power allocation for each pile is judged, the output power of each pile is determined based on the judgment result, and a power allocation instruction is generated. The power weighting coefficient is calculated based on the power upper limit control coefficient and the power allocation formula coefficient matrix, including: ； Where [wPr,wP,wPask] represents the power allocation formula coefficient matrix, which is configured according to user needs, and wPr+wP+wPask>0; This indicates the rated power and charging power of each charging pile; This indicates the real-time charging power of each charging pile; This indicates the read power requirement of the BMS.

2. The multi-AC / DC charging pile group control system according to claim 1, characterized in that, The main control layer also includes virtual power plants and smart microgrid strategy machines; The virtual power plant is used for the aggregation of distributed energy resources and power dispatch. The intelligent microgrid strategy unit is used to integrate local energy and provide voltage input to the current transformer area; The flexible load group control module is also used to acquire power data from the virtual power plant and the smart microgrid strategy machine, and to regulate the charging power in conjunction with the transformer substation and the preset flexible load group control algorithm.

3. A method for flexible load group control of charging piles, characterized in that, In the flexible load group control module of the multi-AC / DC charging pile group control system as described in claim 1 or 2, the configuration data of the main control layer includes: the upper limit of transformer power capacity; the operation data of the main control layer includes: the real-time measured power of the transformer; The configuration data of the device layer includes: the number of each pile, the type of each pile, the rated power of each pile, and the upper and lower limits of the charging power; the operation data of the device layer includes: the battery connection status of each pile, the real-time charging power of each pile, the power requirement read by the BMS, and the real-time data of the BMS. The configuration data of the field control layer includes: control time interval, power regulation margin, power upper limit control coefficient, and power allocation formula coefficient matrix.

4. The flexible load group control method for charging piles according to claim 3, characterized in that, The determination of the total station power setpoint based on the real-time total charging power of the charging piles, the configuration data of the on-site sub-control layer, and the configuration and operation data of the main control layer includes: The overload monitoring formula is used to determine whether the transformer is overloaded; the overload monitoring formula is as follows: ； in, Indicates the power regulation margin. Indicates the upper limit of transformer power capacity. This indicates the measured power of the transformer; If the overload monitoring formula holds true, then the total station power setpoint... The calculation formula is: ； in, This represents the power upper limit control coefficient. This represents the total real-time charging power. If the overload monitoring formula does not hold, then the total station power setpoint will be adjusted. Set as the upper limit of transformer power capacity .

5. The flexible load group control method for charging piles according to claim 4, characterized in that, When the main control layer includes a virtual power plant and a smart microgrid strategy unit, the step of determining the total station power setpoint based on the real-time total charging power of charging piles, the configuration data of the field sub-control layer, and the configuration and operation data of the main control layer further includes: Determine whether the current moment is within the power command time range, and based on the determination result, determine the intermediate power variable to be executed, expressed by the formula: ； in, This represents the intermediate power variable; tv0~tv1 represents the instruction time period of the virtual power plant; tx0~tx1 represents the instruction time period of the smart microgrid strategy machine. Based on the current real-time total charging power P and the intermediate power variable The relationship determines whether to execute the power intermediate variable; like ,and Then execute the intermediate power variable; like ,and If true, then the validity of the power command is judged. The formula for judging validity is: ； in, Indicates the upper limit of charging power. This indicates the lower limit of charging power, and n represents the total number of charging stations. If the validity judgment formula is not met, the power command response will not be executed and an alarm will be triggered; if the validity judgment formula is met, the power command response will be executed and the power setpoints for the entire station will be updated. .

6. The flexible load group control method for charging piles according to claim 3, characterized in that, Based on the SOC weighting coefficient, power weighting coefficient, and total station power setpoint, the power distribution for each pile is calculated, including: The power distribution formula for each pile is as follows: ； in, This indicates the current pile power allocation value. Indicates the power weighting coefficient. This represents the SOC weighting coefficient.

7. The flexible load group control method for charging piles according to claim 3, characterized in that, The legality of the power allocation for each pile is determined, and the output power of each pile is determined based on the determination result, including: The legality judgment formula is as follows: ； in, This indicates the current power allocation value for the piles; If the validity judgment formula is not met, then the remaining charging piles are obtained. The remaining charging piles include j piles whose current power allocation value is lower than Pdn_j, and k piles whose current power allocation value is higher than Pup_i. The power of the remaining charging piles is reset, and the power reset formula is: ； Calculate the remaining allocated power: ； The remaining allocated power of the charging piles is recalculated based on the remaining allocated power and the allocated power formula. The legality of the remaining charging piles after the power redistribution is judged again until the power of all charging piles is legal, and the output power of each pile is obtained.

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