Distributed V2G device with electric energy quality adjusting function and method

Abstract

The invention belongs to the technical field of distributed new energy access and intelligent power grid control, solves the problem that in the prior art, reactive compensation cannot be dynamically injected and sucked when the voltage of a power grid rises, and the support for the voltage stability of the power grid is limited, and provides distributed V2G equipment with an electric energy quality adjusting function and a method. The distributed V2G equipment with the standby power quality adjusting function comprises a power grid side interface unit and a battery side interface unit; the input end of a first voltage-sharing module of the battery side interface unit is connected with the input end of a first power module, and the output end of the first voltage-sharing module is connected with the output end of a second power module; the input end of the second voltage-sharing module is connected with the input end of the second power module, and the output end of the second voltage-sharing module is connected with the output end of the first power module. The adaptability and stability of equipment in a weak power grid environment can be improved.

Description

Technical Field

[0001] This invention belongs to the field of smart distribution network and electric vehicle-grid interaction technology, specifically relating to a distributed V2G device and method with power quality regulation function. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the widespread adoption of electric vehicles, numerous distributed charging and discharging facilities are being connected to the distribution network, posing new challenges to the power flow distribution, voltage stability, and power quality of the distribution network. Traditional electric vehicle charging equipment typically only has unidirectional charging or simple bidirectional charging and discharging functions. As a passive load or power source for the power grid, it cannot respond to changes in the operating status of the distribution network and lacks the ability to actively support the grid, further affecting the stability of the distribution network. In modern distribution networks with a high proportion of distributed power sources, especially in "weak grid" areas with high impedance (such as communities), problems such as voltage fluctuations, frequency deviations, and insufficient reactive power are becoming increasingly prominent.

[0004] Traditional power grid two-way energy exchange (V2G) systems employ current source (PI / PID) control to support DC charging and discharging control of the electric vehicle battery-side BMS (Battery Management System), enabling both charging and discharging of electrical energy. For the large-scale integration of renewable energy, the energy management system monitors and regulates photovoltaic output and charging pile loads in real time, smoothing reverse power flow and optimizing the power factor. Simultaneously, harmonic mitigation devices are configured to reduce the impact of high-frequency harmonics. However, existing control strategies passively respond to preset commands during grid frequency changes, leading to drastic fluctuations in charging and discharging power, which is detrimental to grid frequency stability. In high-impedance (weak grid) scenarios, they are slow to perceive and insufficiently respond to changes in grid voltage amplitude, easily causing zero-crossing distortion of the AC current waveform and affecting power quality. Furthermore, they lack the ability to actively provide reactive power, failing to dynamically inject reactive power compensation during grid voltage fluctuations, thus limiting their support for grid voltage stability. Summary of the Invention

[0005] To address at least one of the technical problems mentioned above, this invention provides a distributed V2G device and method with power quality regulation function, which can improve the adaptability and stability of the device in a weak power grid environment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a distributed V2G device with power quality regulation function.

[0007] A distributed V2G device with power quality regulation function includes: a grid-side interface unit and a battery-side interface unit; The input terminal of the grid-side interface unit is connected to the AC distribution network to form a grid connection point, so as to support bidirectional transmission of active and reactive power through real-time monitoring of the grid connection point electrical parameters; the battery-side interface unit includes an input power unit, a transformer, a first power module, a second power module, a first voltage equalization module, and a second voltage equalization module; the output terminal of the grid-side interface unit is connected to the input power unit of the battery-side interface unit; the input power unit is connected to the primary winding of the transformer; The first power module and the second power module are connected in parallel, and their input terminals are respectively connected to the first secondary winding and the second secondary winding of the transformer, and their output terminals are connected to the power battery of the electric vehicle; the input terminal of the first voltage equalization module is connected to the input terminal of the first power module, and the output terminal of the first voltage equalization module is connected to the output terminal of the second power module; the input terminal of the second voltage equalization module is connected to the input terminal of the second power module, and the output terminal of the second voltage equalization module is connected to the output terminal of the first power module.

[0008] In one implementation, the first voltage equalization module and the second voltage equalization module have the same structure, both being full-bridge rectifier circuits. They achieve autonomous and continuous adjustment of port parameters and automatic equalization of voltage and current between ports solely through the electrical characteristics and dynamic balance principle of their own hardware circuits.

[0009] In one implementation, the grid-side interface unit is an AC / DC unit, which is a single-phase Heric full-bridge circuit.

[0010] As one implementation method, when one of the power modules on the electric vehicle's power battery side fails, the faulty power module is isolated and automatically switched to another power module for derating operation.

[0011] A second aspect of the present invention provides a control method for a distributed V2G device with power quality regulation function.

[0012] A control method for a distributed V2G device with power quality regulation function, comprising: By default, the distributed V2G device with power quality regulation function is controlled in DC power control mode, with the battery-side interface unit dominating power regulation and the grid-side interface unit only maintaining the stability of the intermediate DC bus voltage. The system acquires grid status, load reactive power demand, and superior command information, and controls the distributed V2G device with power quality regulation function to switch to the corresponding working mode based on this acquired information. When there is power limitation on the grid side, the AC power limiting control mode is activated, and the power is adjusted in coordination between the grid side interface unit and the battery side interface unit. When the information obtained above meets the reactive power control triggering conditions, the reactive power control mode is activated. When a power grid failure occurs, the off-grid discharge control mode is automatically activated.

[0013] As one implementation method, under the charging condition of DC power control mode, the grid-side interface unit is in AC-DC conversion mode and adopts dual closed-loop control of voltage outer loop and current inner loop. The voltage outer loop tracks the DC reference voltage, and the current inner loop tracks the current command output by the outer loop to ensure that the bus voltage fluctuation is within the allowable range. The power module of the battery-side interface unit responds to the BMS command of the electric vehicle battery and achieves constant voltage, constant current and constant power charging by adjustment.

[0014] In one implementation, under the discharge condition of DC power control mode, the grid-side interface unit switches from AC-DC conversion mode to inverter mode to maintain the stability of the bus voltage; the power module of the battery-side interface unit controls the discharge power of the electric vehicle battery and injects electrical energy into the grid through phase shifting regulation.

[0015] In one implementation, under the charging condition of AC power limiting control mode, if the available power of the grid is greater than or equal to the power required by the power module of the battery-side interface unit, the grid-side interface unit maintains bus voltage regulation, and the power module of the battery-side interface unit controls the power according to the electric vehicle battery BMS command, and the power module of the battery-side interface unit controls the power. If the available power of the grid is less than the power required by the power module of the battery-side interface unit, the DC voltage is regulated by the power module of the battery-side interface unit, and the power of the power module of the battery-side interface unit is not controlled, responding to changes in the power value of the preceding stage.

[0016] As one implementation method, the reactive power control mode includes reactive power control under normal operation and reactive power compensation control. The triggering condition for reactive power control under normal operation is: calculating the current power factor or reactive power according to the grid status and comparing it with the preset target value, and finding that there is a reactive power deficit or surplus. The triggering condition for reactive power compensation control is: the reactive power demand of the load exceeds the set threshold or the upper level issues a reactive power compensation command.

[0017] In one implementation, under off-grid discharge control mode, the grid-side interface unit switches to a voltage source inverter, and stabilizes the local microgrid through dual closed-loop control of the voltage outer loop and the current inner loop. The power module of the battery-side interface unit adjusts the discharge power according to the critical load demand.

[0018] The beneficial effects of this invention are: The distributed V2G device with power quality regulation function of the present invention consists of a grid-side interface unit and a battery-side interface unit. As a distributed intelligent node deployed on the user side of the distribution network, the device can not only realize bidirectional energy interaction with the grid, but more importantly, it can sense the deviation of voltage and frequency at the grid connection point in real time, and dynamically adjust the active and reactive power exchanged with the grid accordingly. This provides the distribution network with rapid voltage support and frequency response, integrates active grid support and power quality management functions, improves the adaptability and stability of the device in weak grid environments, and realizes wide voltage range automatic voltage equalization design through innovative hardware circuits, meeting the needs of 7kW household low-power scenarios and high-voltage vehicle platforms. It also realizes orderly charging and discharging, and enhances the active support for grid operation and power quality regulation capabilities.

[0019] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a topology diagram of a distributed V2G device with power quality regulation function according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit operation of the first voltage equalization module according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the circuit operation of the second voltage equalization module according to an embodiment of the present invention; Figure 4 This is a control block diagram of the power grid side interface unit according to an embodiment of the present invention; Figure 5 This is a block diagram of reactive current compensation control according to an embodiment of the present invention; Figure 6 This is a power module charging control block diagram of the battery-side interface unit according to an embodiment of the present invention; Figure 7 This is a power module discharge control block diagram of the battery-side interface unit according to an embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] In this invention, terms such as "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "side," and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only to facilitate the description of the structural relationships of the various components or elements of this invention and do not specifically refer to any component or element in this invention. They should not be construed as limiting the invention.

[0026] In this invention, terms such as "fixed connection," "connected," and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0027] Most existing distributed single-phase low-power V2G charging piles have a narrow charging and discharging range, and the DC voltage level cannot meet the wide voltage range charging and discharging function requirements of 200Vdc-1000Vdc. In order to broaden the DC voltage range, the power module of the battery-side interface unit adopts a two-way series-parallel connection. However, the two-way series-parallel connection will bring voltage and current equalization problems. This invention designs a voltage equalization module. The voltage equalization module adopts a full-bridge rectifier circuit. It realizes the autonomous and continuous adjustment of port parameters and the automatic equalization of voltage and current between ports only through its own hardware circuit electrical characteristics and dynamic balance principle. This greatly simplifies the system control complexity. With the hardware's real-time response characteristics, it ensures the ultimate reliability and fast response of the voltage equalization process.

[0028] according to Figure 1This invention provides a distributed V2G device with power quality regulation function, comprising: a grid-side interface unit and a battery-side interface unit; the input terminal of the grid-side interface unit is connected to the AC distribution network to form a grid connection point, so as to support bidirectional transmission of active / reactive power through real-time monitoring of the grid connection point electrical parameters; the battery-side interface unit includes an input power unit, a transformer, a first power module, a second power module, a first voltage equalization module, and a second voltage equalization module; the output terminal of the grid-side interface unit is connected to the input power unit of the battery-side interface unit; the input power unit is connected to the primary winding of the transformer.

[0029] In this embodiment, the grid-side interface unit is an AC / DC unit, which is a single-phase Heric full-bridge circuit with a power of 7kW. The topology of the single-phase Heric full-bridge circuit includes IGBT switching transistors, inductor filtering, and voltage / current sampling modules, enabling efficient transmission of active power between the grid and the grid. It also has independent and rapid bidirectional reactive power regulation capabilities, thus laying the hardware foundation for participating in power quality management functions such as reactive power compensation, power factor correction, and voltage regulation in the distribution network.

[0030] It should be noted that in other embodiments, the grid-side interface unit may also be implemented using AC / DC units with other topologies, which will not be described in detail here.

[0031] In this embodiment, the first power module and the second power module are connected in parallel, and their input terminals are respectively connected to the first secondary winding and the second secondary winding of the transformer, and their output terminals are connected to the power battery of the electric vehicle; the input terminal of the first voltage equalization module is connected to the input terminal of the first power module, and the output terminal of the first voltage equalization module is connected to the output terminal of the second power module; the input terminal of the second voltage equalization module is connected to the input terminal of the second power module, and the output terminal of the second voltage equalization module is connected to the output terminal of the first power module.

[0032] exist Figure 1 In the middle, V a L is the actual grid-connected voltage. g1 and L g2 For the filter inductor, i g For grid-connected current, V bus The input voltage for the battery-side interface unit; L6 and C r These are the inductors and capacitors connected to the primary winding of the transformer; S1-S6 and Q1-Q4 are all IGBT switching transistors; C o1 and C o2These are the filter capacitors for the first and second power modules, respectively; the input terminals of the first power module are connected to Asec_MidL and Asec_MidR, respectively; the positive output terminal of the first power module is Asec_VO+, and the negative output terminal is Asec_VO-; the input terminals of the second power module are connected to Bsec_MidL and Bsec_MidR, respectively; the positive output terminal of the second power module is Bsec_VO+, and the negative output terminal is Bsec_VO-; the output voltages of the first and second power modules are respectively V. o1 and V o2 .

[0033] In this embodiment, the power module is a DC / DC module. The DC / DC converter uses two 3.5kW dual active bridge (DAB) non-resonant modules connected in parallel, forming a matched power unit with the preceding 7kW AC / DC module. Combined with the flexible series / parallel configuration capability of the output ports, it achieves an ultra-wide DC output voltage range of 200V-1000V and possesses inherent fault tolerance. When a single DAB module fails, it can be isolated, and the remaining modules can be automatically switched to derated operation, thereby ensuring uninterrupted operation of core functions such as V2G or emergency charging.

[0034] In this embodiment, the first voltage equalization module and the second voltage equalization module have the same structure, both being full-bridge rectifier circuits. They achieve autonomous and continuous adjustment of port parameters and automatic equalization of voltage and current between ports solely through the electrical characteristics and dynamic balance principle of their own hardware circuits, without any software algorithm intervention. This greatly simplifies the system control complexity, and the hardware's instant response characteristics ensure the extreme reliability and rapid response of the voltage equalization process.

[0035] The following is combined Figure 2 and Figure 3 The working principles of the first and second voltage equalization modules are given below: Both the first and second voltage equalization modules are rectifier full-bridge circuit structures; D1-D4 are diodes, and C1 and C2 are filter capacitors; L g1 and L g2 For filtering inductors; The input terminals of the first voltage equalization module are connected to Asec_MidL and Asec_MidR, which are connected in the first secondary winding of the transformer; the output terminals of the first voltage equalization module are connected to the output terminals Bsec_VO+ and Bsec_VO- of the second power module, as follows. Figure 2 As shown; The input end of the second voltage equalizing module is connected to Bsec_MidL and Bsec_MidR, and Bsec_MidL and Bsec_MidR are connected in the second secondary winding of the transformer; the output end of the second voltage equalizing module is connected to the output ends Asec_VO+ and Asec_VO- of the first power module, as Figure 3 shown.

[0036] The voltage between Asec_VO+ and Asec_VO- is ; the voltage between Bsec_VO+ and Bsec_VO- is ; when the PWM signal drives the bidirectional dual-active bridge switch tube to conduct, and : If the voltage of Asec_MidL > the voltage of Asec_MidR, the rectifying full bridge conducts in the positive half cycle, and the electric energy is transferred from the A-phase bridge arm to the B-phase bridge arm to achieve automatic voltage equalization; if the voltage of Asec_MidL < the voltage of Asec_MidR, the rectifying full bridge conducts in the negative half cycle, and the charging and voltage equalization from the A-phase bridge arm to the B-phase bridge arm are also achieved.

[0037] Similarly, when : If the voltage of Bsec_MidL > the voltage of Bsec_MidR, the rectifying full bridge conducts in the positive half cycle, and at this time, the B-phase bridge arm charges the A-phase bridge arm to achieve automatic voltage equalization; if the voltage of Bsec_MidL < the voltage of Bsec_MidR, the rectifying full bridge conducts in the negative half cycle, and the charging and voltage equalization from the B-phase bridge arm to the A-phase bridge arm are also completed.

[0038] The following details the control process of the distributed V2G device with power quality regulation function in the embodiment of the present invention: By default, control the distributed V2G device with power quality regulation function to be in the DC power control mode, use the battery-side interface unit to dominate power regulation, and use the grid-side interface unit to only maintain the stability of the output DC voltage; Obtain the grid status, load reactive power demand and superior command information, and control the distributed V2G device with power quality regulation function to switch to the corresponding working mode according to the obtained information: When there is a power limit on the grid side, start the AC power limit control mode, and use the grid-side interface unit and the battery-side interface unit to jointly regulate power; When the obtained information reaches the reactive power regulation trigger condition, start the reactive power regulation mode; When a grid fault (such as power outage, voltage dip) occurs, automatically activate the off-grid discharge control mode.

[0039] The grid-side interface unit, serving as the interaction interface between the power grid and the intermediate DC bus, possesses grid support capabilities. It can sample grid voltage amplitude and frequency in real time. Its core function is to achieve four-quadrant operation of active power (P) / reactive power (Q). During charging, it monitors grid voltage and frequency in real time. When grid voltage and frequency are outside the threshold range, it compensates the grid by actively reducing power, generating reactive power, or adjusting the power factor (PF). Figure 4 As shown, under the charging condition of DC power control mode, the grid-side interface unit (i.e., AC / DC unit) is in AC / DC conversion mode and adopts dual closed-loop control of voltage outer loop and current inner loop. The voltage outer loop tracks the DC reference voltage, and the current inner loop tracks the current command output by the outer loop to ensure that the bus voltage fluctuation is within the allowable range.

[0040] exist Figure 4 In the process, the inputs to the voltage control loop are the grid-connected side voltage reference value VL_ref and the DC bus voltage reference value Vdc_ref, which are respectively correlated with the actual grid-connected voltage V. a The difference between the actual DC bus voltage Vdc and the output voltage is used to obtain the corresponding output voltage after off-grid / grid switching. Combined with the power P_PI output by the power control loop, the output current reference value Id_ref is limited to provide a reference for the current control loop.

[0041] Active and reactive power calculation module: Collects grid current Ig and grid voltage Ug, extracts the positive and negative sequence components of the signals through two SOGI (second-order generalized integrators), and then calculates active and reactive power to provide data support for power control. The reactive power calculated by the active and reactive power calculation module, based on the reactive power reference value Qref, combined with the d-axis current reference value output from the voltage control loop, constitutes the control benchmark for the current loop.

[0042] Phase-locked loop (PLL): Input grid voltage Ug, output power factor angle θ, providing a synchronization angle for dq / αβ coordinate transformation, realizing the conversion between stationary and rotating coordinate systems.

[0043] Coordinate transformation module: Through αβ / dq transformation, the current I in the stationary coordinate system is transformed. α and I β Converted to current I in a rotating coordinate system d and I q Then, through the dq / αβ inverse transformation, the control quantity in the rotating coordinate system is converted back to the stationary coordinate system to adapt to the subsequent modulation stage.

[0044] Power control loop: input power reference value Pref and actual power P, output power P_PI.

[0045] The current control loop is divided into two paths, which perform closed-loop control on the d-axis and q-axis currents respectively. The difference between the actual current and the reference current is adjusted, and the output control quantity is filtered by low-pass filter (LPF) and arctangent operation (tanθ) before participating in subsequent modulation.

[0046] The output signals of the integrated current control loop are used to generate the SPWM (sinusoidal pulse width modulation) drive waveform.

[0047] Q flag This is the reactive power status, used to identify the current reactive power control status, Q. flag =0、Q flag =1、Q flag =2, triggering the corresponding working mode respectively, thereby adjusting the operating logic of the reactive power control loop.

[0048] The power module (i.e., DC / DC module) of the battery-side interface unit responds to the electric vehicle battery BMS commands and achieves constant voltage, constant current, and constant power charging through adjustment (e.g., PI control). When the switch is open, S=0, such as... Figure 6 As shown, MIN represents taking the minimum value, which is the minimum value of the output signal of the voltage loop PI control and the output signal of the current loop PI control, and the corresponding PWM drive signal is generated according to the corresponding control / modulation algorithm.

[0049] Under DC power control mode discharge conditions, the grid-side interface unit (i.e., AC / DC unit) switches from AC / DC conversion mode to inverter mode to maintain bus voltage stability; the power module (i.e., DC / DC module) of the battery-side interface unit controls the electric vehicle battery discharge power and injects electrical energy into the grid through phase shifting regulation. At this time, the switch is open, S=0, as... Figure 7 As shown, MIN represents taking the minimum value, which is the minimum value of the output signal of the bus voltage loop PI control and the output signal of the current loop PI control, and the corresponding PWM drive signal is generated according to the corresponding control / modulation algorithm.

[0050] Under AC power-limited control mode charging conditions, if the available grid power P_grid ≥ the required power P_dc of the power module (i.e., DC / DC module) of the battery-side interface unit, then the grid-side interface unit (i.e., AC / DC unit) maintains bus voltage regulation, and the power module (i.e., DC / DC module) of the battery-side interface unit controls power according to the electric vehicle battery BMS command. The power module (i.e., DC / DC module) of the battery-side interface unit controls the power, the switch is open, and the switch signal S=0 is defined; if the available grid power < the required power of the power module (i.e., DC / DC module) of the battery-side interface unit, the DC voltage is regulated by the power module (i.e., DC / DC module) of the battery-side interface unit, the power of the power module (i.e., DC / DC module) of the battery-side interface unit is uncontrolled, responding to changes in the preceding power value, and the switch signal S=1 is defined. Figure 6 As shown.

[0051] Under the discharge condition of AC power-limited control mode, the power coordination logic is the same as that under the charging condition, and the control block diagram is as follows: Figure 7 As shown.

[0052] Reactive power control modes include reactive power control under normal operation and reactive power compensation control. The triggering condition for reactive power control under normal operation is: calculating the current power factor or reactive power based on the grid status and comparing it with the preset target value, and finding that there is a reactive power deficit or surplus. The triggering condition for reactive power compensation control is: the reactive power demand of the load exceeds the set threshold or the upper level issues a reactive power compensation command.

[0053] Under reactive power control during normal operation: The grid-side interface unit (i.e., the AC / DC unit) dominates reactive power regulation, achieving "±" P (Active bidirectional), ± Q The specific control logic for the "(Reactive bidirectional)" four-quadrant operation is as follows: reactive power ( Q ref Control: Set the reactive power reference value to... Q ref Reactive power control is achieved through PI regulation; Power factor (PF) control: Set the power factor reference value to 100%. PF ref ; through formula The reactive power command is calculated, and then closed-loop control is achieved through PI regulation; Q ref This is a reference value for reactive power. P Active power The power factor angle.

[0054] In the reactive power compensation control process, the load current is sampled in real time to decompose it into active and reactive components. The decomposed active current is then subjected to low-pass filtering to remove high-frequency noise interference, and then summed and averaged periodically to obtain smoother and more accurate active current information for subsequent calculations and analysis.

[0055] Reactive power compensation calculation and control: such as Figure 5 As shown, based on the current decomposition results and the system's set compensation target (reactive power), the reactive current that needs to be compensated is calculated to improve the reactive power distribution and voltage quality of the power grid. , , , ; ; ; PF Here, P is the power factor, Q is the active power, and S is the reactive power. The power factor angle, I q1 To compensate for the reactive current, I Load_d_av The average active current after low-pass filtering; I Load_q This is the reactive current after low-pass filtering.

[0056] By monitoring real-time grid status (such as voltage, frequency, power factor, etc.), load reactive power demand, and superior commands, the system automatically determines whether to operate in conventional reactive power control mode or reactive power compensation mode. When the triggering conditions for reactive power compensation mode are met, it smoothly switches to that mode; when the compensation target is achieved or the triggering conditions disappear, it automatically switches back to conventional reactive power control mode, ensuring that the system can operate efficiently and stably under different operating scenarios, achieving comprehensive control and optimized compensation of grid reactive power.

[0057] In off-grid discharge control mode, the grid-side interface unit (i.e., AC / DC unit) switches to a voltage source inverter, with the output voltage set to 220V / 50Hz. The local microgrid is stabilized through dual closed-loop control of the voltage outer loop and the current inner loop. The power module of the battery-side interface unit adjusts the discharge power according to the critical load demand.

[0058] This invention, through an innovative three-tiered collaborative architecture of "grid interaction - battery management - hardware voltage equalization," fundamentally transforms the device from a "one-way power conversion terminal" to a "flexible smart grid node with plug-and-play capabilities." This invention offers the following beneficial effects: Active grid support: The grid-side interface unit can integrate independent active / reactive power decoupling control, dynamically respond to changes in grid status, realize reactive power compensation and voltage regulation, and improve the operational stability of weak grids.

[0059] Wide voltage compatibility and intelligent fault tolerance: The battery-side interface unit is designed in series and parallel to support a wide voltage range of 200V-1000V; the hardware-based independent voltage equalization mechanism combined with the system-level fault tolerance strategy ensures that the system can continue to operate at reduced derating after the faulty module is isolated, ensuring uninterrupted core functions.

[0060] Integrated and economical design: By deeply integrating grid support functions into the equipment, eliminating the need for external governance devices, this approach reduces system complexity and deployment costs while providing a feasible path for large-scale distributed applications.

[0061] This invention represents a paradigm shift from "external passive governance" to "endogenous active support." Traditional solutions rely on independent energy management systems and harmonic control devices for centralized V2G system regulation. This invention designs the grid-side interface unit as an intelligent node with multi-mode autonomous capabilities, enabling it to perform reactive power compensation, power factor correction, voltage support, and even off-grid power supply in real time without external intervention. Simultaneously, the battery-side interface unit's power module (i.e., DC / DC module) adopts a modular dual active bridge topology, achieving efficient compatibility across an ultra-wide voltage range of 200-1000V. This invention employs an integrated multi-energy distributed architecture, significantly improving system response speed, compatibility, and reliability. Furthermore, it upgrades the device from a single power interaction terminal to a plug-and-play, bidirectional interactive, user-grade "energy router," providing fundamental support for building a highly resilient distribution network.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A distributed V2G device with power quality regulation function, characterized in that, include: Power grid side interface unit and battery side interface unit; The input terminal of the grid-side interface unit is connected to the AC distribution network to form a grid connection point, so as to support bidirectional transmission of active and reactive power through real-time monitoring of the grid connection point electrical parameters; the battery-side interface unit includes an input power unit, a transformer, a first power module, a second power module, a first voltage equalization module, and a second voltage equalization module; the output terminal of the grid-side interface unit is connected to the input power unit of the battery-side interface unit; the input power unit is connected to the primary winding of the transformer; The first power module and the second power module are connected in parallel, and their input terminals are respectively connected to the first secondary winding and the second secondary winding of the transformer, and their output terminals are connected to the power battery of the electric vehicle; the input terminal of the first voltage equalization module is connected to the input terminal of the first power module, and the output terminal of the first voltage equalization module is connected to the output terminal of the second power module; the input terminal of the second voltage equalization module is connected to the input terminal of the second power module, and the output terminal of the second voltage equalization module is connected to the output terminal of the first power module.

2. The distributed V2G device with power quality regulation function as described in claim 1, characterized in that, The first voltage equalization module and the second voltage equalization module have the same structure, both being full-bridge rectifier circuits.

3. The distributed V2G device with power quality regulation function as described in claim 1, characterized in that, The grid-side interface unit is an AC / DC unit, which is a single-phase Heric full-bridge circuit.

4. The distributed V2G device with power quality regulation function as described in claim 1, characterized in that, When one of the power modules on the battery side of an electric vehicle fails, the system automatically switches to another power module for derating operation by isolating the faulty power module.

5. A control method for a distributed V2G device with power quality regulation function as described in any one of claims 1-4, characterized in that, include: By default, the distributed V2G device with power quality regulation function is controlled in DC power control mode, with the battery-side interface unit dominating power regulation and the grid-side interface unit only maintaining the stability of the intermediate DC bus voltage. The system acquires grid status, load reactive power demand, and superior command information, and controls the distributed V2G device with power quality regulation function to switch to the corresponding working mode based on this acquired information. When there is power limitation on the grid side, the AC power limiting control mode is activated, and the power is adjusted in coordination between the grid side interface unit and the battery side interface unit. When the information obtained above meets the reactive power control triggering conditions, the reactive power control mode is activated. When a power grid failure occurs, the off-grid discharge control mode is automatically activated.

6. The control method for a distributed V2G device with power quality regulation function as described in claim 5, characterized in that, In the DC power control mode of charging, the grid-side interface unit is in AC-DC conversion mode and adopts dual closed-loop control with voltage outer loop and current inner loop. The voltage outer loop tracks the DC reference voltage, and the current inner loop tracks the current command output by the outer loop to ensure that the bus voltage fluctuation is within the allowable range. The power module of the battery-side interface unit responds to the BMS command of the electric vehicle battery and achieves constant voltage, constant current and constant power charging by adjustment.

7. The control method for a distributed V2G device with power quality regulation function as described in claim 5, characterized in that, Under the discharge condition of DC power control mode, the grid-side interface unit switches from AC-DC conversion mode to inverter mode to maintain the stability of the bus voltage; the power module of the battery-side interface unit controls the discharge power of the electric vehicle battery and injects electrical energy into the grid through phase shift regulation.

8. The control method for a distributed V2G device with power quality regulation function as described in claim 5, characterized in that, Under AC power limiting control mode charging conditions, if the available power of the grid is greater than or equal to the power demand of the power module of the battery-side interface unit, the grid-side interface unit maintains bus voltage regulation, and the power module of the battery-side interface unit controls the power according to the electric vehicle battery BMS command, and the power module of the battery-side interface unit controls the power. If the available power of the grid is less than the power demand of the power module of the battery-side interface unit, the DC voltage is regulated by the power module of the battery-side interface unit, and the power of the power module of the battery-side interface unit is not controlled, responding to changes in the power value of the preceding stage.

9. The control method for a distributed V2G device with power quality regulation function as described in claim 5, characterized in that, The reactive power control mode includes reactive power control under normal operation and reactive power compensation control. The triggering condition for reactive power control under normal operation is: calculate the current power factor or reactive power according to the grid status and compare it with the preset target value, and there is a reactive power deficit or surplus. The triggering condition for reactive power compensation control is: the reactive power demand of the load exceeds the set threshold or the upper level issues a reactive power compensation command.

10. The control method for a distributed V2G device with power quality regulation function as described in claim 5, characterized in that, In off-grid discharge control mode, the grid-side interface unit switches to a voltage source inverter, which stabilizes the local microgrid through dual closed-loop control of the voltage outer loop and the current inner loop. The power module of the battery-side interface unit adjusts the discharge power according to the critical load demand.

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