Vehicle network interaction control system based on V2G and control method thereof

Abstract

The invention discloses a V2G-based vehicle network interaction control system and a control method thereof, the system comprises a charging and discharging cloud platform, a V2G equipment core controller, a first V2G unit and a second V2G unit, the charging and discharging cloud platform and the V2G equipment core controller are in communication connection, and the V2G equipment core controller is electrically connected with the first V2G unit and the second V2G unit. According to the vehicle network interaction control method based on the V2G, each module can be utilized to the maximum extent, and the endless loss of electric quantity is reduced during charging or discharging. The charging or discharging requirements of the vehicle can be flexibly met, and one device can be used for charging and discharging. Meanwhile, the charge and discharge process is finely controlled, power compensation control is carried out by considering the influence of the residual electric quantity of the battery and the discharge depth limitation on the actual output power of the vehicle battery, the charge / discharge demand power is adjusted by adopting a fuzzy control adjustment method, and the accuracy of charge and discharge power control is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of V2G charging columns, and in particular to a V2G-based vehicle-grid interactive control system and a control method thereof. Background Art

[0002] The concept of V2G was proposed by Amory Lovins in 1995. It is a two-way interconnection technology that realizes vehicle-grid interaction. Its core lies in making full use of electric vehicle battery energy storage from vehicles to the power grid, so that electric vehicles can be used as a load and also as part of the power supply energy storage. With the continuous development of V2G technology, it can not only reduce the potential load impact of electric vehicle charging on the power system, but also enable the energy stored in electric vehicle batteries to be sustainably utilized, playing the role of "peak shaving and valley filling" for the power grid. The potential of V2G technology mainly depends on the reliability of vehicles participating in power supply at the right time, consumer acceptance, the life and discharge rate of electric vehicle batteries, etc.

[0003] The development and use of V2G technology has also achieved high benefits. (1) V2G technology uses electric vehicle batteries as a buffer for the power grid, providing auxiliary services for the power grid, such as peak load regulation and reactive power compensation; (2) The discharge function can provide additional income for car owners, offset part of the cost of purchasing electric vehicles, and is conducive to the popularization of clean cars; (3) It can increase the stability and reliability of the power grid and reduce the operating costs of the power system. In addition, in the long run, the application of V2G technology can also reduce investment in new power generation infrastructure; increase the number of electric vehicles, reduce the use of fuel vehicles, and thus reduce greenhouse gas emissions.

[0004] However, the current V2G charging column technology does not provide sufficient control over the charging and discharging process.

[0005] The subjects and objects of its charging and discharging include power grids and electric vehicles, and the methods include charging and discharging. That is, this charging mode can have up to four paths per unit time, while the traditional power grid has only one path to charge electric vehicles. If it cannot be controlled in a refined manner, it may cause unsafe factors in the power grid or electric vehicles during the charging and discharging process, and also affect the performance of the electric vehicle. Summary of the invention

[0006] The purpose of the present invention is to provide a vehicle-grid interactive control system based on V2G and a control method thereof, and a control method and system for realizing mutual transmission of electric energy between electric vehicles and AC power grids based on V2G technology, so that users can discharge to the power grid during peak hours of electricity consumption and charge during low hours of electricity consumption, thereby increasing user income, and the car can also be used as an energy storage part to store excess electricity, and realize refined control of the charging and discharging process, thereby solving the shortcomings of the existing technology.

[0007] The present invention is implemented by the following technical solutions: a V2G-based vehicle-grid interactive control system, comprising a charging and discharging cloud platform, a V2G device core controller, a first V2G unit, and a second V2G unit, wherein the charging and discharging cloud platform and the V2G device core controller are connected to each other in a communication manner, and the V2G device core controller is electrically connected to the first V2G unit and the second V2G unit;

[0008] The first V2G unit includes three first V2G modules, the second V2G unit includes three second V2G modules, the three first V2G modules and the three second V2G modules are connected to the first DC bus and the second DC bus at their DC ends, a bus contactor KM5 is connected between the positive poles of the first DC bus and the second DC bus, and a bus contactor KM6 is connected between the negative poles of the first DC bus and the second DC bus;

[0009] The AC ends of the three first V2G modules and the three second V2G modules are connected to the three-phase AC power grid through AC contactors 1TC and 2TC respectively;

[0010] The positive and negative poles of the first DC bus are connected to the first charging gun through DC contactors KM1 and KM3 respectively, and the positive and negative poles of the second DC bus are connected to the second charging gun through DC contactors KM2 and KM4 respectively;

[0011] The DC contactors KM1, KM2, KM3, KM4, the AC contactors 1TC, 2TC, and the bus contactors KM5 and KM6 are all electrically connected to the V2G equipment core controller.

[0012] Furthermore, the three-phase AC power grid is connected to a three-phase AC power meter, the first DC bus and the second DC bus are both connected to a two-phase DC power meter, and the V2G device core controller is electrically connected to the three-phase AC power meter and the two-phase DC power meter.

[0013] Furthermore, fuses FU1 and FL1 are respectively connected between the first DC bus and the DC contactors KM1 and KM3, and fuses FU2 and FL2 are respectively connected between the second DC bus and the DC contactors KM2 and KM4.

[0014] Furthermore, the V2G device core controller is also electrically connected to a display.

[0015] Furthermore, the V2G device core controller is electrically connected to the working start-up sections of the three first V2G modules and the three second V2G modules.

[0016] The present invention also proposes a control method for the vehicle-grid interactive control system based on the above V2G, including the following control process:

[0017] (1) Disconnect the single-gun charging process and single-gun discharging process of the bus contactors KM5 and KM6:

[0018] In the single-gun charging process, the AC contactor 1TC or 2TC is closed, and the V2G module under the corresponding charging line of the AC contactor 1TC or 2TC is controlled to convert AC power into DC power. Then the DC contactor under the corresponding charging line of the AC contactor 1TC or 2TC is closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device.

[0019] In the single-charger discharge process, the DC contactor corresponding to the first or second charging gun is closed, and the V2G module under the corresponding discharge circuit of the first or second charging gun is controlled to convert DC power into AC power. The AC contactor under the corresponding discharge circuit of the first or second charging gun is controlled to close to transmit AC power to the grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the core controller of the V2G device.

[0020] (2) Close the bus contactors KM5 and KM6 to connect two groups of V2G modules in parallel, and then perform the single-gun charging and single-gun discharging processes:

[0021] In the single-charger charging process, the AC contactors 1TC and 2TC are closed, and the V2G modules under the corresponding lines of the AC contactors 1TC and 2TC are controlled to convert AC power into DC power. Then the DC contactors under the first charging gun or the second charging gun are closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device.

[0022] In the single-charger discharge process, the DC contactor corresponding to the first charging gun or the second charging gun is closed, and the V2G modules under the corresponding lines of the first charging gun and the second charging gun are controlled to convert DC power into AC power. The AC contactors 1TC and / or 2TC are controlled to close to transmit AC power to the grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the V2G device core controller.

[0023] (3) Close the bus contactors KM5 and KM6 to connect the two groups of V2G modules in parallel to form a dual-gun charging process and a dual-gun discharging process:

[0024] In the dual-charger charging process, the AC contactor 1TC and / or 2TC is closed, and the V2G module under the corresponding line of the AC contactor 1TC and / or 2TC is controlled to convert AC power into DC power. Then the DC contactors under the first charging gun and the second charging gun are closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device.

[0025] In the dual-gun discharge process, the DC contactors corresponding to the first charging gun and the second charging gun are closed, and the V2G modules under the corresponding lines of the first charging gun and / or the second charging gun are controlled to convert DC power into AC power. The AC contactors 1TC and / or 2TC are controlled to close to transmit AC power to the power grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the V2G device core controller.

[0026] (4) Disconnect the single-gun charging process and single-gun discharging process of the bus contactors KM5 and KM6:

[0027] The single-gun charging process and the single-gun discharging process described in process (1) are adopted, and when the first charging gun performs the single-gun charging process, the second charging gun performs the single-gun discharging process, and when the first charging gun performs the single-gun discharging process, the second charging gun performs the single-gun charging process;

[0028] (5) Close the bus contactors KM5 and KM6 to connect two groups of V2G modules in parallel, and then perform the single-gun charging and single-gun discharging processes:

[0029] The single-gun charging process and the single-gun discharging process described in process (2) are adopted, and when the first charging gun performs the single-gun charging process, the second charging gun performs the single-gun discharging process, and when the first charging gun performs the single-gun discharging process, the second charging gun performs the single-gun charging process.

[0030] Further, when 0kW<charge / discharge required power<=20kW, one V2G module is started, and the charge / discharge power is the charge / discharge required power;

[0031] When 20kW<charge / discharge required power<=40kW, start two V2G modules, and the charge / discharge power is the charge / discharge required power;

[0032] When 40kW<charge / discharge required power<=60kW, start 3 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0033] When 60kW<charge / discharge required power<=80kW, start 4 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0034] When 80kW<charge / discharge required power<=100kW, start 5 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0035] When 100kW<charge / discharge required power<=120kW, start 6 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0036] When 120kW<the required charging / discharging power, 6 V2G modules are started and the charging / discharging power is 120kW.

[0037] Furthermore, the calculation method of the charging / discharging required power is:

[0038] (1) Charging power requirement:

[0039] First determine the rated capacity C of the electric vehicle battery battery and the expected charging time t charge ; Charging power requirement P charge The calculation formula is: where η c For battery charging efficiency;

[0040] (2) Discharge power requirement:

[0041] When considering the battery discharge efficiency, the actual power output of the vehicle battery (kW) is denoted as P battery-output , and its calculation formula is:

[0042] Among them, P grid-receive is the power expected to be received by the grid side, η discharge is the discharge efficiency of the vehicle battery, η discharge The value is between 0 and 1;

[0043] Furthermore, after obtaining the required discharge power, the actual output power of the vehicle battery is calculated in combination with the remaining battery power and the discharge depth limit, and based on the actual output power of the vehicle battery, the bus contactors KM5 and KM6 are closed to start the double-gun discharge, and the control signal duty cycle of the start compensation V2G module is calculated, where:

[0044] The actual output power of the vehicle battery is calculated based on the remaining battery power and the discharge depth limit, as follows:

[0045]

[0046] Among them, P bao is the maximum power that the battery can actually output, C r is the current remaining capacity of the vehicle battery; DOD is the depth of discharge of the battery, expressed as a percentage; t mo is the discharge time corresponding to the maximum power output of the battery, C mo The battery can output the maximum power;

[0047] The calculation control strategy starts the compensation V2G module, specifically:

[0048] Subtract the actual maximum output power from the discharge demand power to obtain the compensation power. Based on the compensation power, the control signal duty cycle of the DC / AC circuit that starts the compensation V2G module is calculated using the following formula:

[0049]

[0050] Among them, K x To obtain the duty cycle of the control signal, W Δ To compensate the power, P max is the maximum output power of the V2G module, K max is the duty cycle corresponding to the maximum output power of the V2G module.

[0051] Furthermore, after the V2G module is started, the charging / discharging required power is adjusted using a fuzzy control adjustment method, specifically:

[0052] Input variable selection, including but not limited to battery remaining capacity, charge and discharge voltage, charge and discharge current, charge and discharge capacity, grid voltage deviation, grid frequency deviation as input variables for fuzzy control;

[0053] Fuzzification processing, fuzzifying the input variables into different language values ​​and determining the membership function of each language value;

[0054] Establish a rule base, establish fuzzy rules based on experience and experiments, and form rule discrimination condition functions;

[0055] Fuzzy reasoning and decision making: when the input variables have specific values, reasoning is performed according to fuzzy rules to obtain fuzzy outputs;

[0056] Defuzzification, the center of gravity method is used to convert the fuzzy output into an accurate charging and discharging power value, and the charging and discharging power is controlled by adjusting the duty cycle of the V2G control signal.

[0057] Advantages of the present invention:

[0058] 1. The vehicle-grid interactive control system based on V2G technology realizes the unification of the charging system and the discharging system. The electric vehicle battery is used as a buffer for the power grid to provide auxiliary services for the power grid. During peak power consumption, electric vehicles act as external power sources to discharge to the power grid, and users can obtain excess income; during low power consumption, electric vehicles can be used as energy storage devices to store excess electricity and reduce power loss.

[0059] 2. The V2G-based vehicle-grid interactive control method can maximize the use of each module and reduce unnecessary power loss during charging or discharging. It can flexibly meet the charging or discharging needs of the vehicle, and one device can charge and discharge.

[0060] 3. Fine-tune the control of the charging and discharging process, including power compensation control considering the impact of the remaining battery power and discharge depth limit on the actual output power of the vehicle battery. The adjustment of the charging / discharging demand power adopts the fuzzy control adjustment method to improve the accuracy of the charging and discharging power control. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0062] Figure 1 A hardware schematic diagram of a V2G charging device according to an embodiment of the present invention;

[0063] Figure 2 This is a communication diagram between a V2G charging device and a platform according to an embodiment of the present invention;

[0064] Figure 3 This is a control diagram of a V2G charging device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] Example 1

[0067] like Figure 1 , 3 As shown, a V2G-based vehicle-grid interactive control system includes a charging and discharging cloud platform, a V2G device core controller, a first V2G unit, and a second V2G unit. The charging and discharging cloud platform and the V2G device core controller are connected with communication, and the V2G device core controller is electrically connected with the first V2G unit and the second V2G unit;

[0068] The first V2G unit includes three first V2G modules, and the second V2G unit includes three second V2G modules. The DC ends of the three first V2G modules and the three second V2G modules are respectively connected to the first DC bus and the second DC bus. The positive poles of the first DC bus and the second DC bus are connected to the bus contactor KM5, and the negative poles of the first DC bus and the second DC bus are connected to the bus contactor KM6;

[0069] The AC ends of the three first V2G modules and the three second V2G modules are connected to the three-phase AC grid through AC contactors 1TC and 2TC respectively;

[0070] The positive and negative poles of the first DC bus are connected to the first charging gun through DC contactors KM1 and KM3 respectively, and the positive and negative poles of the second DC bus are connected to the second charging gun through DC contactors KM2 and KM4 respectively;

[0071] DC contactors KM1, KM2, KM3, KM4, AC contactors 1TC, 2TC, and bus contactors KM5 and KM6 are all electrically connected to the V2G equipment core controller.

[0072] In this embodiment, a three-phase AC power meter is connected to the three-phase AC power grid, a two-phase DC power meter is connected to the first DC bus and the second DC bus, and the V2G device core controller is electrically connected to the three-phase AC power meter and the two-phase DC power meter.

[0073] In this embodiment, fuses FU1 and FL1 are respectively connected between the first DC bus and the DC contactors KM1 and KM3, and fuses FU2 and FL2 are respectively connected between the second DC bus and the DC contactors KM2 and KM4.

[0074] In this embodiment, the V2G device core controller is also electrically connected to the display.

[0075] In this embodiment, the V2G device core controller is electrically connected to the working start-up sections of the three first V2G modules and the three second V2G modules.

[0076] The principle of the present invention is: each gun of the V2G device corresponds to a group of V2G modules and one AC incoming line, with a total of two groups of V2G modules and two AC incoming lines. The two groups of V2G modules are connected in parallel and disconnected through the mother contactor, and each gun can be charged or discharged independently without being affected by the start-up state of the other gun. When a single gun is charged, the V2G module converts AC power into DC power to realize vehicle charging. When a single gun is discharged, the V2G module converts DC power into AC power and inputs it into the power grid. When one gun is charged and the other gun is discharged, the two guns are charged or discharged independently without affecting each other.

[0077] In order to achieve the above purpose, the present invention takes a 120kW dual-gun V2G device as an example to illustrate the V2G vehicle-grid interactive control strategy. The technical solution is as follows:

[0078] 1. This type of equipment includes 2G equipment core controller, two direct-connected meters, two AC meters, two AC contactors, six 20kW charging and discharging modules, auxiliary sources and other types of switches, relays, etc. Participating strategy controllers include: charging cloud platform, V2G equipment core controller.

[0079] 2. Functions that the charging cloud platform needs to realize

[0080] like Figure 2 As shown, a charging start or discharging start command is sent to the V2G device, and charging or discharging data sent by the receiving device.

[0081] 3. Functions implemented by the core controller of V2G equipment

[0082] (1) Exchange information with the charging cloud platform.

[0083] (2) Execute the charging or discharging command to control the V2G device to start the charging or discharging process.

[0084] (3) Control the start-up of the V2G charging and discharging modules and start the corresponding number of modules according to vehicle demand.

[0085] 4. V2G vehicle-network interaction control principles

[0086] (1) The charging process is separated from the discharging process. Each charging gun can start charging or discharging independently. A dual-gun V2G device can start charging with one gun and discharging with the other gun at the same time.

[0087] (2) When starting the V2G module, it is started according to the unit power, where the unit power is the rated power of a single module.

[0088] Example 2

[0089] The present invention also proposes a control method for the vehicle-grid interactive control system based on the above V2G, including the following control process:

[0090] (1) Disconnect the single-gun charging process and single-gun discharging process of the bus contactors KM5 and KM6:

[0091] In the single-gun charging process, the AC contactor 1TC or 2TC is closed, and the V2G module under the corresponding charging line of the AC contactor 1TC or 2TC is controlled to convert AC power into DC power. Then the DC contactor under the corresponding charging line of the AC contactor 1TC or 2TC is closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device.

[0092] In the single-charger discharge process, the DC contactor corresponding to the first or second charging gun is closed, and the V2G module under the corresponding discharge circuit of the first or second charging gun is controlled to convert DC power into AC power. The AC contactor under the corresponding discharge circuit of the first or second charging gun is controlled to close to transmit AC power to the grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the core controller of the V2G device.

[0093] (2) Close the bus contactors KM5 and KM6 to connect two groups of V2G modules in parallel, and then perform the single-gun charging and single-gun discharging processes:

[0094] In the single-charger charging process, the AC contactors 1TC and 2TC are closed, and the V2G modules under the corresponding lines of the AC contactors 1TC and 2TC are controlled to convert AC power into DC power. Then the DC contactors under the first charging gun or the second charging gun are closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device.

[0095] In the single-charger discharge process, the DC contactor corresponding to the first charging gun or the second charging gun is closed, and the V2G modules under the corresponding lines of the first charging gun and the second charging gun are controlled to convert DC power into AC power. The AC contactors 1TC and / or 2TC are controlled to close to transmit AC power to the grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the V2G device core controller.

[0096] (3) Close the bus contactors KM5 and KM6 to connect the two groups of V2G modules in parallel to form a dual-gun charging process and a dual-gun discharging process:

[0097] In the dual-charger charging process, the AC contactor 1TC and / or 2TC is closed, and the V2G module under the corresponding line of the AC contactor 1TC and / or 2TC is controlled to convert AC power into DC power. Then the DC contactors under the first charging gun and the second charging gun are closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device.

[0098] In the dual-gun discharge process, the DC contactors corresponding to the first charging gun and the second charging gun are closed, and the V2G modules under the corresponding lines of the first charging gun and / or the second charging gun are controlled to convert DC power into AC power. The AC contactors 1TC and / or 2TC are controlled to close to transmit AC power to the power grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the V2G device core controller.

[0099] (4) Disconnect the single-gun charging process and single-gun discharging process of the bus contactors KM5 and KM6:

[0100] The process (1) is a single-gun charging process and a single-gun discharging process, and when the first charging gun performs the single-gun charging process, the second charging gun performs the single-gun discharging process, and when the first charging gun performs the single-gun discharging process, the second charging gun performs the single-gun charging process;

[0101] (5) Close the bus contactors KM5 and KM6 to connect two groups of V2G modules in parallel, and then perform the single-gun charging and single-gun discharging processes:

[0102] The process (2) of single-gun charging process and single-gun discharging process is adopted, and when the first charging gun performs the single-gun charging process, the second charging gun performs the single-gun discharging process, and when the first charging gun performs the single-gun discharging process, the second charging gun performs the single-gun charging process.

[0103] In this embodiment, when 0kW<charge / discharge required power<=20kW, one V2G module is started, and the charge / discharge power is the charge / discharge required power;

[0104] When 20kW<charge / discharge required power<=40kW, start two V2G modules, and the charge / discharge power is the charge / discharge required power;

[0105] When 40kW<charge / discharge required power<=60kW, start 3 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0106] When 60kW<charge / discharge required power<=80kW, start 4 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0107] When 80kW<charge / discharge required power<=100kW, start 5 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0108] When 100kW<charge / discharge required power<=120kW, start 6 V2G modules, and the charge / discharge power is the charge / discharge required power;

[0109] When 120kW<the required charging / discharging power, 6 V2G modules are started and the charging / discharging power is 120kW.

[0110] In this embodiment, the calculation method of the charge / discharge required power is:

[0111] (1) Charging power requirement:

[0112] First determine the rated capacity C of the electric vehicle battery battery and the expected charging time t charge ; Charging power requirement P charge The calculation formula is: where η c For battery charging efficiency;

[0113] (2) Discharge power requirement:

[0114] When considering the battery discharge efficiency, the actual power output of the vehicle battery (kW) is denoted as P battery-output, and its calculation formula is:

[0115] Among them, P grid-receive is the power expected to be received by the grid side, η discharge is the discharge efficiency of the vehicle battery, η di sch arge The value is between 0 and 1;

[0116] In this embodiment, after obtaining the required discharge power, the actual output power of the vehicle battery is calculated in combination with the remaining battery power and the discharge depth limit, and based on the actual output power of the vehicle battery, the bus contactors KM5 and KM6 are closed, the double-gun discharge is started, and the control signal duty cycle of the start compensation V2G module is calculated, where:

[0117] The actual output power of the vehicle battery is calculated based on the remaining battery power and the discharge depth limit, as follows:

[0118]

[0119] Among them, P bao is the maximum power that the battery can actually output, C r is the current remaining capacity of the vehicle battery; DOD is the depth of discharge of the battery, expressed as a percentage; t mo is the discharge time corresponding to the maximum power output of the battery, C mo The battery can output the maximum power;

[0120] The calculation control strategy starts the compensation V2G module, specifically:

[0121] Subtract the actual maximum output power from the discharge demand power to obtain the compensation power. Based on the compensation power, the control signal duty cycle of the DC / AC circuit that starts the compensation V2G module is calculated. The calculation formula is:

[0122]

[0123] Among them, K x To obtain the duty cycle of the control signal, W Δ To compensate the power, P max is the maximum output power of the V2G module, K max is the duty cycle corresponding to the maximum output power of the V2G module.

[0124] In this embodiment, after the V2G module is started, the charging / discharging required power is adjusted using a fuzzy control adjustment method, specifically:

[0125] Input variable selection, including but not limited to battery remaining capacity, charge and discharge voltage, charge and discharge current, charge and discharge capacity, grid voltage deviation, and grid frequency deviation as input variables for fuzzy control. For example, the battery remaining capacity reflects the energy state of the battery, and it is not suitable to discharge if it is too low; the grid frequency and voltage deviation reflect the stability of the grid, and when the deviation is large, the vehicle needs to participate in the adjustment.

[0126] Fuzzy processing converts input variables into different language values. For example, the remaining battery power can be divided into "low", "medium" and "high"; the grid frequency deviation and voltage deviation can be divided into "negative large", "negative small", "zero", "positive small" and "positive large", etc. And determine the membership function of each language value, so that the precise measurement value can be converted into a fuzzy concept.

[0127] The rule base is established, and fuzzy rules are established based on experience and experiments. For example, "if the remaining battery power is high and the grid voltage deviation is positive, the discharge power is large", etc., covering various input variable combinations.

[0128] Fuzzy reasoning and decision-making, when the input variable has a specific value, reasoning is performed according to the fuzzy rules to obtain the fuzzy output. For example, by calculating the activation strength of each rule, the fuzzy set membership of the output variable (charging and discharging power) is determined.

[0129] Defuzzification, using the centroid method to convert the fuzzy output into an accurate charge and discharge power value, so as to adjust the V2G charge and discharge power and achieve effective matching of the battery and grid status. Among them, the centroid method is a commonly used defuzzification method. Assume that the charge and discharge power fuzzy output obtained by fuzzy reasoning is a fuzzy set, which contains multiple elements with non-zero membership. The centroid method is to determine the accurate charge and discharge power value by calculating the centroid of the fuzzy set. For example, if there are three elements in the fuzzy output set (low power, medium power, high power), their corresponding memberships are 0.3, 0.5, and 0.2, respectively, and assuming that the low power is 1kW, the medium power is 3kW, and the high power is 5kW, then the accurate charge and discharge power value calculated by the centroid method is (1×0.3+3×0.5+5×0.2) / (0.3+0.5+0.2)=2.8kW. In charging and discharging power adjustment, when the fuzzy rules involve multiple factors (such as battery status and grid status) and the output fuzzy set is relatively complex, the centroid method can comprehensively consider various possible power output situations and obtain a more reasonable and accurate power adjustment value.

[0130] In summary, the beneficial effects of the present invention are:

[0131] 1. The vehicle-grid interactive control system based on V2G technology realizes the unification of the charging system and the discharging system. The electric vehicle battery is used as a buffer for the power grid to provide auxiliary services for the power grid. During peak power consumption, electric vehicles act as external power sources to discharge to the power grid, and users can obtain excess income; during low power consumption, electric vehicles can be used as energy storage devices to store excess electricity and reduce power loss.

[0132] 2. The V2G-based vehicle-grid interactive control method can maximize the use of each module and reduce unnecessary power loss during charging or discharging. It can flexibly meet the charging or discharging needs of the vehicle, and one device can charge and discharge.

[0133] 3. Fine-tune the control of the charging and discharging process, including power compensation control considering the impact of the remaining battery power and discharge depth limit on the actual output power of the vehicle battery. The adjustment of the charging / discharging demand power adopts the fuzzy control adjustment method to improve the accuracy of the charging and discharging power control.

[0134] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A vehicle-grid interactive control system based on V2G, characterized in that: It includes a charging and discharging cloud platform, a V2G device core controller, a first V2G unit, and a second V2G unit. The charging and discharging cloud platform and the V2G device core controller are connected to each other in a communication manner, and the V2G device core controller is electrically connected to the first V2G unit and the second V2G unit. The first V2G unit includes three first V2G modules, the second V2G unit includes three second V2G modules, the three first V2G modules and the three second V2G modules are connected to the first DC bus and the second DC bus at their DC ends, a bus contactor KM5 is connected between the positive poles of the first DC bus and the second DC bus, and a bus contactor KM6 is connected between the negative poles of the first DC bus and the second DC bus; The AC ends of the three first V2G modules and the three second V2G modules are connected to the three-phase AC power grid through AC contactors 1TC and 2TC respectively; The positive and negative poles of the first DC bus are connected to the first charging gun through DC contactors KM1 and KM3 respectively, and the positive and negative poles of the second DC bus are connected to the second charging gun through DC contactors KM2 and KM4 respectively; The DC contactors KM1, KM2, KM3, KM4, the AC contactors 1TC, 2TC, and the bus contactors KM5 and KM6 are all electrically connected to the V2G equipment core controller.

2. A V2G-based vehicle-grid interactive control system according to claim 1, characterized in that: The three-phase AC power grid is connected to a three-phase AC power meter, the first DC bus and the second DC bus are both connected to a two-phase DC power meter, and the V2G device core controller is electrically connected to the three-phase AC power meter and the two-phase DC power meter.

3. The V2G-based vehicle-grid interactive control system according to claim 1, characterized in that: The first DC busbar is connected to the DC contactors KM1 and KM3 with fuses FU1 and FL1, respectively. The second DC busbar is connected to the DC contactors KM2 and KM4 with fuses FU2 and FL2, respectively.

4. A V2G-based vehicle-grid interactive control system according to claim 2, characterized in that: The V2G device core controller is also electrically connected to a display.

5. The V2G-based vehicle-grid interactive control system according to claim 1, characterized in that: The V2G device core controller is electrically connected to the working start-up sections of the three first V2G modules and the three second V2G modules.

6. A control method for a V2G vehicle-grid interactive control system based on any one of claims 1-5, characterized in that: The control flow includes the following: (1) Disconnect the single-gun charging process and single-gun discharging process of the bus contactors KM5 and KM6: In the single-gun charging process, the AC contactor 1TC or 2TC is closed, and the V2G module under the corresponding charging line of the AC contactor 1TC or 2TC is controlled to convert AC power into DC power. Then the DC contactor under the corresponding charging line of the AC contactor 1TC or 2TC is closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device. In the single-charger discharge process, the DC contactor corresponding to the first or second charging gun is closed, and the V2G module under the corresponding discharge circuit of the first or second charging gun is controlled to convert DC power into AC power. The AC contactor under the corresponding discharge circuit of the first or second charging gun is controlled to close to transmit AC power to the grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the core controller of the V2G device. (2) Close the bus contactors KM5 and KM6 to connect two groups of V2G modules in parallel, and then perform the single-gun charging and single-gun discharging processes: In the single-charger charging process, the AC contactors 1TC and 2TC are closed, and the V2G modules under the corresponding lines of the AC contactors 1TC and 2TC are controlled to convert AC power into DC power. Then the DC contactors under the first charging gun or the second charging gun are closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device. In the single-charger discharge process, the DC contactor corresponding to the first charging gun or the second charging gun is closed, and the V2G modules under the corresponding lines of the first charging gun and the second charging gun are controlled to convert DC power into AC power. The AC contactors 1TC and / or 2TC are controlled to close to transmit AC power to the grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the V2G device core controller. (3) Close the bus contactors KM5 and KM6 to connect the two groups of V2G modules in parallel to form a dual-gun charging process and a dual-gun discharging process: In the dual-charger charging process, the AC contactor 1TC and / or 2TC is closed, and the V2G module under the corresponding line of the AC contactor 1TC and / or 2TC is controlled to convert AC power into DC power. Then the DC contactors under the first charging gun and the second charging gun are closed to input DC power into the electric vehicle. The corresponding DC meter obtains the charging voltage, charging current, and charging power of the corresponding gun during charging and sends them to the core controller of the V2G device. In the dual-gun discharge process, the DC contactors corresponding to the first charging gun and the second charging gun are closed, and the V2G modules under the corresponding lines of the first charging gun and / or the second charging gun are controlled to convert DC power into AC power. The AC contactors 1TC and / or 2TC are controlled to close to transmit AC power to the power grid. The AC meter obtains the discharge voltage, discharge current, and discharge power of the corresponding gun during discharge and sends them to the V2G device core controller. (4) Disconnect the single-gun charging process and single-gun discharging process of the bus contactors KM5 and KM6: The single-gun charging process and the single-gun discharging process described in process (1) are adopted, and when the first charging gun performs the single-gun charging process, the second charging gun performs the single-gun discharging process, and when the first charging gun performs the single-gun discharging process, the second charging gun performs the single-gun charging process; (5) Close the bus contactors KM5 and KM6 to connect two groups of V2G modules in parallel, and then perform the single-gun charging and single-gun discharging processes: The single-gun charging process and the single-gun discharging process described in process (2) are adopted, and when the first charging gun performs the single-gun charging process, the second charging gun performs the single-gun discharging process, and when the first charging gun performs the single-gun discharging process, the second charging gun performs the single-gun charging process.

7. The control method of the V2G vehicle-grid interactive control system according to claim 6, characterized in that: When 0kW<required charging / discharging power<=20kW, start one V2G module, and the charging / discharging power is the required charging / discharging power; When 20kW<charge / discharge required power<=40kW, start two V2G modules, and the charge / discharge power is the charge / discharge required power; When 40kW<charge / discharge required power<=60kW, start 3 V2G modules, and the charge / discharge power is the charge / discharge required power; When 60kW<charge / discharge required power<=80kW, start 4 V2G modules, and the charge / discharge power is the charge / discharge required power; When 80kW<charge / discharge required power<=100kW, start 5 V2G modules, and the charge / discharge power is the charge / discharge required power; When 100kW<charge / discharge required power<=120kW, start 6 V2G modules, and the charge / discharge power is the charge / discharge required power; When 120kW<the required charging / discharging power, 6 V2G modules are started and the charging / discharging power is 120kW.

8. The control method of the V2G vehicle-grid interactive control system according to claim 7, characterized in that: The calculation method of the charging / discharging required power is: (1) Charging power requirement: First determine the rated capacity C of the electric vehicle battery battery and the expected charging time t charge ; Charging power requirement P charge The calculation formula is: where η c For battery charging efficiency; (2) Discharge power requirement: When considering the battery discharge efficiency, the actual power output of the vehicle battery (kW) is denoted as P battery-output , and its calculation formula is: Among them, P grid-receive is the power expected to be received by the grid side, η discharge is the discharge efficiency of the vehicle battery, η discharge The value is between 0 and 1; 9. The control method of the V2G vehicle-grid interactive control system according to claim 8, characterized in that: After obtaining the required discharge power, the actual output power of the vehicle battery is calculated in combination with the remaining battery power and the discharge depth limit. Based on the actual output power of the vehicle battery, the bus contactors KM5 and KM6 are closed to start the double-gun discharge, and the control signal duty cycle of the start compensation V2G module is calculated, where: The actual output power of the vehicle battery is calculated based on the remaining battery power and the discharge depth limit, as follows: C mo =C r ×DOD Among them, P bao is the maximum power that the battery can actually output, C r is the current remaining capacity of the vehicle battery; DOD is the depth of discharge of the battery, expressed as a percentage; t mo is the discharge time corresponding to the maximum power output of the battery, C mo The battery can output the maximum power; The calculation control strategy starts the compensation V2G module, specifically: Subtract the actual maximum output power from the discharge demand power to obtain the compensation power. Based on the compensation power, the control signal duty cycle of the DC / AC circuit that starts the compensation V2G module is calculated using the following formula: Among them, K x To obtain the duty cycle of the control signal, W Δ To compensate the power, P max is the maximum output power of the V2G module, K max is the duty cycle corresponding to the maximum output power of the V2G module.

10. The control method of the V2G vehicle-grid interactive control system according to claim 7, characterized in that: After the V2G module is started, the charging / discharging required power is adjusted using a fuzzy control adjustment method, specifically: Input variable selection, including but not limited to battery remaining capacity, charge and discharge voltage, charge and discharge current, charge and discharge capacity, grid voltage deviation, grid frequency deviation as input variables for fuzzy control; Fuzzification processing, fuzzifying the input variables into different language values ​​and determining the membership function of each language value; Establish a rule base, establish fuzzy rules based on experience and experiments, and form rule discrimination condition functions; Fuzzy reasoning and decision making: when the input variables have specific values, reasoning is performed according to fuzzy rules to obtain fuzzy outputs; Defuzzification, the center of gravity method is used to convert the fuzzy output into an accurate charging and discharging power value, and the charging and discharging power is controlled by adjusting the duty cycle of the V2G control signal.

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