Charging station resource scheduling system and method based on bridge arm balance

Abstract

The invention relates to the technical field of power grid resource scheduling, in particular to a charging station resource scheduling system and method based on bridge arm balance, and the system comprises a switching control module, a charging and discharging adjustment module, a common bus switching module and a bridge arm balance control module. The switching control module monitors the power grid three-phase load state corresponding to the charging station in real time, and generates a phase switching instruction when detecting that the unbalance degree exceeds a threshold value; the common bus switching module receives the phase switching instruction and dynamically accesses the input side of the charging station to a target power grid phase; the charging and discharging adjusting module generates a modulation signal based on the power distribution instruction, and controls the switching time sequence of power subunits in the commutation power module; and the bridge arm balance control module comprises a three-phase bridge arm circuit, generates a compensation signal according to the voltage deviation and feeds back the compensation signal to the charging and discharging adjustment module, so as to maintain the energy balance of the three-phase bridge arm circuit of the charging station. According to the invention, the problem that the reliability of the system is reduced due to the dynamic unbalance of the bridge arm energy of the multi-level converter is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of power grid resource scheduling technology, and in particular to a charging station resource scheduling system and method based on bridge arm balancing. Background Technology

[0002] As the interface between electric vehicles and the power grid, the operating efficiency and stability of charging stations directly affect the charging experience of electric vehicles and the load management of the power grid. In order to improve charging and discharging efficiency and meet higher charging and discharging demands, more and more charging stations are beginning to adopt modular multilevel converter technology. This technology achieves efficient energy conversion by having multiple power modules work in parallel and can provide a more stable current output.

[0003] Current mainstream technologies mainly rely on two approaches. The first is a fixed phase allocation strategy, which statically binds charging piles to a specific phase of the power grid. This method cannot respond to real-time load changes in the grid, resulting in insufficient utilization of lightly loaded phase resources while the capacitor voltage of heavily loaded phases continuously rises, exacerbating inter-phase energy imbalance. The second approach is voltage control based on circulating current suppression, which suppresses voltage fluctuations by injecting compensation components into the bridge arm current. However, this method mainly targets low-frequency components and has limited effectiveness in suppressing harmonic fluctuations caused by high-frequency switching operations. Furthermore, it struggles to coordinate energy interaction between upper and lower bridge arms, leading to additional electrical stress on power devices. In summary, neither existing technology has established a dynamic coordination mechanism between vehicle charging status and grid operating status. When a vehicle in a specific charging state connects to a heavily loaded phase, the instantaneous energy surge in the bridge arm can trigger systemic imbalance.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides a charging station resource scheduling system and method based on bridge arm balancing, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A charging station resource scheduling system based on bridge arm balancing, the system comprising:

[0008] Switching control module, charging and discharging regulation module, common bus switching module and bridge arm balance control module;

[0009] The switching control module monitors the three-phase load status of the power grid corresponding to the charging station in real time, and generates a phase switching command when the unbalance exceeds the threshold.

[0010] The common bus switching module receives the phase switching command and dynamically connects the charging station input side to the target power grid phase;

[0011] The charge / discharge regulation module generates a modulation signal based on the power allocation command to control the switching timing of the power sub-units;

[0012] The bridge arm balance control module includes a three-phase bridge arm circuit, which is used to convert the modulation signal into DC charging power, collect the current and capacitor voltage of each phase bridge arm in real time, generate a compensation signal based on the voltage deviation and feed it back to the charge and discharge regulation module to maintain the energy balance of the three-phase bridge arm circuit of the charging station.

[0013] Furthermore, the three-phase bridge arm circuit is divided into an upper bridge arm unit and a lower bridge arm unit, and each phase bridge arm includes two in-phase and symmetrical upper bridge arm units and lower bridge arm units;

[0014] The upper and lower bridge arm units of each phase bridge arm include a plurality of power sub-units and bridge arm smoothing reactances connected in series.

[0015] Furthermore, the power subunit includes:

[0016] Switching device group, rectifier diode group, energy storage capacitor, resistor;

[0017] The switching device group includes a first switching device and a second switching device, which switch the switching state according to the input control signal to regulate the current, and realize voltage rise and fall and current distribution based on alternating conduction and turn-off.

[0018] The rectifier diode group includes a first diode and a second diode connected in parallel with the first switching device and the second switching device, respectively, for providing a unidirectional current flow path and performing a freewheeling operation when the switching device group is turned off;

[0019] The energy storage capacitor is connected to the switching device group and the rectifier diode group to temporarily store energy and balance the power load and stabilize the output voltage when the load fluctuates.

[0020] The resistor and the energy storage capacitor form an RC network, which is used to improve circuit stability, limit instantaneous overcurrent, and dissipate excess energy.

[0021] Furthermore, the bridge arm balance control module, when performing balancing, includes:

[0022] The upper arm current of the upper arm unit and the lower arm current of the lower arm unit in each phase arm are collected respectively, and the real-time voltage of the energy storage capacitor in each power sub-unit is collected simultaneously.

[0023] Calculate the absolute current difference between the upper bridge arm current and the lower bridge arm current, and the absolute voltage difference between the capacitor voltages of the power sub-units in phase.

[0024] When the absolute current difference exceeds a preset current threshold, or the absolute voltage difference exceeds a preset voltage threshold, the compensation signal is generated. The compensation signal includes a phase compensation angle for adjusting the carrier phase and a quantity correction value for correcting the number of power submodules switched.

[0025] The compensation signal is input to the charge-discharge adjustment module, which corrects the phase offset of the carrier wave according to the phase compensation angle, and dynamically adjusts the number of power sub-modules put into operation in the upper bridge arm unit and the lower bridge arm unit according to the quantity correction value.

[0026] Furthermore, the average voltage control of the capacitor in each phase arm includes:

[0027] The voltage of the energy storage capacitor of all power sub-units in each phase bridge arm is acquired in real time.

[0028] Calculate the average capacitor voltage of each phase arm in the three-phase bridge arm circuit, and calculate the total average capacitor voltage of the three-phase bridge arm circuit based on the average capacitor voltage.

[0029] When the deviation between the average value of the capacitor voltage of any phase bridge arm and the average value of the total capacitor voltage exceeds a preset tolerance, a switching timing adjustment command is generated.

[0030] The switching timing adjustment command is sent to the charge / discharge regulation module;

[0031] The charge / discharge regulation module reallocates the conduction time of the power sub-units of the phase bridge arm with excessive deviation according to the switching timing adjustment command, so that the average value of the capacitor voltage approaches the average value of the total capacitor voltage.

[0032] Furthermore, the upper and lower bridge arm capacitor voltage balance control includes:

[0033] The sum of the capacitor voltages of all power sub-units in the upper arm unit of each phase arm is obtained in real time.

[0034] The sum of the capacitor voltages of all power sub-units in the lower arm unit of the in-phase bridge arm is obtained in real time;

[0035] Calculate the active power difference between the sum of the capacitor voltages of the upper and lower bridge arms in phase.

[0036] When the active power difference exceeds a preset difference threshold, a bridge arm power allocation correction instruction is generated. The bridge arm power allocation correction instruction includes the power allocation ratio adjustment value between the upper bridge arm and the lower bridge arm.

[0037] The bridge arm power correction command is input into the charge / discharge regulation module;

[0038] The charge / discharge adjustment module synchronously adjusts the power output time ratio between the upper bridge arm unit and the lower bridge arm unit of the corresponding phase according to the power distribution ratio adjustment value.

[0039] Furthermore, the common bus switching module performs bridge arm switching, including:

[0040] The common bus switching module corresponds to a phase selection switch for each bridge arm;

[0041] The bridge arm imbalance signal sent by the bridge arm balance control module is received, and the bridge arm imbalance signal contains an identifier of the target power grid phase that needs to be switched.

[0042] Disconnect all currently connected bridge arm end switches, and simultaneously close the power input terminal and common bus terminal of the bus switch with the bridge arm end;

[0043] Close the phase selection switch corresponding to the target power grid phase, connect the common bus to the target phase, and simultaneously disconnect the phase selection switches for the other phases.

[0044] Furthermore, the switching control module includes:

[0045] Real-time acquisition of the effective value of the three-phase current of the power grid and the state of charge of the electric vehicle to be connected;

[0046] Compare the effective values ​​of the three-phase currents and identify the grid phase with the lowest load;

[0047] When multiple phase loads are close together, the target grid phase is selected by associating the state of charge.

[0048] Generate the phase switching command containing the identifier of the target power grid phase and output it to the common bus switching module.

[0049] A charging station resource scheduling method based on bridge arm balancing, the method comprising:

[0050] Real-time acquisition of the effective value of the three-phase current of the power grid and the state of charge of the electric vehicle to be connected;

[0051] Based on the effective value of the three-phase current, the target phase with the lowest load is identified, and when the multi-phase loads are similar, the target phase is determined by associating the state of charge.

[0052] Monitor the capacitor voltage of all power sub-units in each phase bridge arm;

[0053] Calculate the average voltage of the capacitor in each phase arm and the average voltage of the total three-phase capacitor;

[0054] When the deviation between the average value of the capacitor voltage of any phase arm and the average value of the total capacitor voltage exceeds a preset tolerance, a conduction time reallocation instruction for the power sub-unit of that phase is generated and executed.

[0055] The sum of the capacitor voltages of the upper and lower bridge arms in phase is acquired in real time, and the active power difference between the sum of the capacitor voltages of the upper and lower bridge arms is calculated.

[0056] When the difference in active power of any phase arm exceeds a preset threshold, the power output time ratio of the upper and lower arms of that phase is generated and adjusted synchronously.

[0057] The technical solution of this invention can achieve the following technical effects:

[0058] It achieves dynamic coordinated control of grid phase, vehicle state of charge and converter arm energy during electric vehicle charging, fundamentally eliminating the systemic reliability risk caused by real-time imbalance of arm energy.

[0059] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 This is a schematic diagram of a charging station resource scheduling system based on bridge arm balancing.

[0062] Figure 2 A schematic diagram of the structure for average control of capacitor voltage in each phase arm;

[0063] Figure 3 A schematic diagram of the upper and lower bridge arm capacitor voltage balance control structure;

[0064] Figure 4 A flowchart illustrating the process of switching bridge arms for the common bus switching module. Detailed Implementation

[0065] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0066] Unless otherwise defined, 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. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0067] Example 1;

[0068] like Figure 1 As shown, this application provides a charging station resource scheduling system based on bridge arm balancing. The system includes:

[0069] Switching control module, charging and discharging regulation module, common bus switching module and bridge arm balance control module;

[0070] The switching control module monitors the three-phase load status of the power grid corresponding to the charging station in real time, and generates a phase switching command when the unbalance exceeds the threshold.

[0071] The common bus switching module receives the phase switching command and dynamically connects the charging station input side to the target grid phase;

[0072] The charge / discharge regulation module generates modulation signals based on power allocation instructions to control the switching timing of power sub-units in the converter power module;

[0073] The bridge arm balance control module includes a three-phase bridge arm circuit, which is used to convert the modulation signal into DC charging power, collect the current and capacitor voltage of each phase bridge arm in real time, generate a compensation signal based on the voltage deviation and feed it back to the charge and discharge regulation module to maintain the energy balance of the three-phase bridge arm circuit of the charging station.

[0074] Specifically, firstly, the switching control module performs real-time monitoring, closely observing the three-phase load status of the power grid. When it detects that the load imbalance of the power grid exceeds a preset threshold, it generates a phase switching command. By monitoring changes in current and voltage imbalance, it prepares for subsequent adjustments. The common bus switching module guides the charging station's input side to connect to the target power grid phase under dynamic conditions. This process ensures that the charging station can flexibly adjust its connection to the power grid to achieve load balance and optimization. Through automatic phase switching, the common bus switching module can more effectively cope with frequent and dynamic load changes in the power grid, thereby improving efficiency. The system enhances the stability of the power grid and the operational efficiency of charging stations. The charge / discharge regulation module generates modulation signals and, based on power allocation commands, controls the switching timing of multiple power sub-units in the converter power module. This supports the operation of the three-phase bridge arm circuit, ensuring that each power sub-unit performs precise power allocation and switching based on the received modulation signals, achieving ideal energy dispatch management. The bridge arm balance control module converts the modulation signals into DC charging power through the three-phase bridge arm circuit. This module collects the current and capacitor voltage of each phase bridge arm in real time, generates compensation signals using voltage deviations, and feeds them back to the charge / discharge regulation module. This feedback mechanism ensures the current balance of the three-phase bridge arms, ensuring that the energy allocation of the charging station is always in an optimal state. The preferred implementation can demonstrate its advantages in specific application scenarios, such as during peak electric vehicle charging periods. In this case, the system automatically adjusts the phase switching between the charging station and the power grid according to the number of vehicles and charging demand. Simultaneously, the bridge arm balance compensation mechanism improves the charging power allocation, effectively offsetting load imbalances within the power grid and improving charging efficiency and stability.

[0075] The technical solution of this invention realizes dynamic coordinated control of grid phase, vehicle state of charge and converter arm energy during electric vehicle charging, fundamentally eliminating the systemic reliability risk caused by real-time imbalance of arm energy.

[0076] Furthermore, the three-phase bridge arm circuit is divided into upper bridge arm units and lower bridge arm units. Each phase bridge arm includes two in-phase and symmetrical upper bridge arm units and lower bridge arm units.

[0077] Each phase arm's upper and lower arm units include several power sub-units connected in series and arm smoothing reactance.

[0078] As a preferred embodiment, the three-phase bridge arm circuit is subdivided into upper bridge arm units and lower bridge arm units. Each phase bridge arm structure includes two in-phase and symmetrical upper bridge arm units and lower bridge arm units. This symmetrical design not only ensures the basic balance of the three-phase circuit operation but also provides physical support for the uniform distribution of current and voltage. Each bridge arm contains several series-connected power sub-units and bridge arm smoothing reactors. These power sub-units are modularly designed components that can be flexibly configured to adapt to the power requirements of different power grids and charging stations. The power sub-units operate in series step by step, working in conjunction with the smoothing reactors, which can effectively suppress transient oscillations caused by current fluctuations, thereby improving the stability of system operation. The upper bridge arm units and lower bridge arm units... Its modular design allows it to adjust power distribution according to different load requirements. For example, when there are many power sub-units, the modules can be switched to achieve precise power matching, thereby ensuring that the in-phase characteristics of the bridge arm circuit are not affected by external load fluctuations. The function of the bridge arm smoothing reactor is to suppress transient frequency oscillations and reduce harmonic interference, thereby improving the power quality of the entire bridge arm circuit by improving the stability of current and voltage. Based on the symmetrical structure and series power sub-unit design, the three-phase bridge arm circuit also has fault redundancy handling capability. If a unit malfunctions, the control system can continue to maintain load balance by shutting down the faulty unit and adjusting the working state of other power sub-units, thereby protecting the stability of the system.

[0079] Furthermore, the power sub-unit includes:

[0080] Switching device group, rectifier diode group, energy storage capacitor, resistor;

[0081] The switching device group includes a first switching device and a second switching device, which switch the switching state according to the input control signal to regulate the current, and realize voltage rise and fall and current distribution based on alternating conduction and turn-off;

[0082] The rectifier diode group includes a first diode and a second diode connected in parallel with the first switching device and the second switching device, respectively, for providing a unidirectional current flow path and performing freewheeling operation when the switching device group is turned off;

[0083] The energy storage capacitor is connected to the switching device group and the rectifier diode group to temporarily store energy and balance the power load and stabilize the output voltage when the load fluctuates.

[0084] Resistors and energy storage capacitors form an RC network, which is used to improve circuit stability, limit transient overcurrent, and dissipate excess energy.

[0085] As a preferred embodiment of the above, the power subunit is designed to optimize the control and distribution of current and voltage, ensuring stable operation of the system under different load conditions, while improving system efficiency and reliability. The power subunit consists of a switching device group, a rectifier diode group, an energy storage capacitor, and a resistor. First, the switching device group is the core regulating component of the power subunit, including a first switching device and a second switching device. These two devices switch between on and off states by receiving input control signals, thereby regulating the current flowing through the power subunit. In a preferred design, the first and second switching devices are insulated-gate bipolar transistors or silicon carbide devices to reduce power consumption and improve switching response speed. The alternating on and off of the switching devices can realize voltage boosting and current distribution functions. For example, when the load power demand changes rapidly, the first switching device can quickly boost the voltage, while the second switching device can protect the circuit from overcurrent surges. The rectifier diode group provides a unidirectional current flow path and includes a first diode and a second diode connected in parallel with the first and second switching devices. In a preferred design, the rectifier diode group is selected with fast current flow characteristics. Diodes with fast recovery characteristics meet high-frequency freewheeling requirements. When the switching device group is in the off state, the rectifier diode group can perform freewheeling operation, continuously transferring electrical energy in the transient circuit to the downstream load. For example, when the load suddenly decreases, the first diode can quickly turn on, avoiding voltage fluctuations caused by instantaneous current interruption, thereby improving system stability. The energy storage capacitor is used to temporarily store electrical energy and balance load fluctuations. It is directly connected between the switching device group and the rectifier diode group. The energy storage capacitor preferably uses a capacitor with high capacitance and low equivalent series resistance to ensure that it can effectively and quickly absorb electrical energy in high-power charging scenarios and provide stable voltage support for the system when the load changes suddenly. For example, during the charging process of electric vehicles, if the load state is switched from low load state to high load state in a short time, the energy storage capacitor can output part of the stored electrical energy to offset the current fluctuations caused by the load surge and maintain voltage stability. The resistor and the energy storage capacitor form an RC network to further improve the stability of the circuit. This design not only limits instantaneous overcurrent, but also avoids overcharging or capacitor overload problems by dissipating excess energy.

[0086] Furthermore, the bridge arm balance control module, when performing balancing, includes:

[0087] The upper arm current of the upper arm unit and the lower arm current of the lower arm unit in each phase arm are collected separately, and the real-time voltage of the energy storage capacitor in each power sub-unit is collected simultaneously.

[0088] Calculate the absolute current difference between the upper and lower bridge arm currents and the absolute voltage difference between the capacitor voltages of the in-phase power sub-units.

[0089] When the absolute current difference exceeds the preset current threshold, or the absolute voltage difference exceeds the preset voltage threshold, a compensation signal is generated. The compensation signal includes a phase compensation angle for adjusting the carrier phase and a quantity correction value for correcting the number of power submodules switched.

[0090] The compensation signal is input to the charge-discharge adjustment module, which corrects the phase offset of the carrier wave according to the phase compensation angle, and dynamically adjusts the number of power sub-modules put into operation in the upper and lower bridge arm units according to the quantity correction value.

[0091] As a preferred embodiment of the above, the first step of the bridge arm balance control module is to collect the upper bridge arm current of the upper bridge arm unit and the lower bridge arm current of the lower bridge arm unit in each phase bridge arm, and simultaneously collect the real-time voltage of the energy storage capacitor in the power sub-unit. In a preferred design, the bridge arm current and capacitor voltage can be measured in real time by high-precision current sensors and voltage sensors, respectively. The sensors are integrated into the bridge arm circuit, and the data from each sensor module is transmitted to the processing unit through a high-speed communication bus to ensure the accuracy and timeliness of data acquisition. For example, when the load of the charging station changes, the sensor can capture transient current changes and quickly transmit the data to the control module for subsequent real-time adjustment. After acquisition, the module calculates the absolute difference between the upper and lower bridge arm currents and the absolute difference between the capacitor voltages of the in-phase power sub-units. When the calculation results show that any difference exceeds a preset threshold, a compensation signal is generated. The compensation signal includes a phase compensation angle for adjusting the carrier phase and a compensation angle for correcting the power sub-unit voltage. The quantity correction value for the number of block switching and the phase compensation angle are dynamically generated by the calculation unit based on the current difference to change the time sequence of the carrier signal operation. The quantity correction value redefines the operating state of the power sub-modules based on the actual load demand. Inputting the generated compensation signal to the charge-discharge regulation module is the key to performing compensation regulation. The charge-discharge regulation module corrects the phase offset of the carrier according to the received phase compensation angle, and dynamically adjusts the number of power sub-modules in operation in the upper and lower bridge arm units according to the quantity correction value. For example, if the load of a bridge arm suddenly increases and the current difference exceeds the threshold, the bridge arm balancing module will generate a negative compensation angle to advance the carrier phase time, and increase the number of operating power sub-modules to balance the current deviation. Similarly, when the capacitor voltage difference exceeds the threshold, the bridge arm balancing module will reduce the number of operating power sub-modules on the high-voltage bridge arm side to restore the voltage deviation to the normal range. In addition, the regulation module monitors the compensation effect in real time during operation to ensure the accuracy and stability of bridge arm control.

[0092] Furthermore, such as Figure 2 As shown, the voltage of the energy storage capacitor of all power sub-units in each phase bridge arm is acquired in real time;

[0093] Calculate the average capacitor voltage of each phase arm in the three-phase bridge arm circuit, and calculate the average total capacitor voltage of the three-phase bridge arm circuit based on the average capacitor voltage.

[0094] When the deviation between the average value of the capacitor voltage of any phase bridge arm and the average value of the total capacitor voltage exceeds the preset tolerance, a switching timing adjustment command is generated.

[0095] Send the switching timing adjustment command to the charge / discharge regulation module;

[0096] The charge / discharge regulation module reallocates the conduction time of the power sub-units of the phase bridge arm with excessive deviation according to the switching timing adjustment command, so that the average value of the capacitor voltage approaches the average value of the total capacitor voltage.

[0097] As a preferred embodiment of the above, specifically, the balance of capacitor voltages among the various power sub-units is an important prerequisite for ensuring the normal operation of the device. Taking the i-th power sub-unit in phase a bridge arm as an example, according to KCL, the following electrical relationship exists:

[0098]

[0099] In the formula K i R is the hybrid loss coefficient. i Equivalent resistance is used for parallel losses; S i (t) is the corresponding switching function; C i Indicates capacitance; u ci (t) represents the input voltage; i(t) represents the current; t represents time; considering only the fundamental frequency component, the current flowing into each power sub-unit can be expressed as:

[0100]

[0101] In the formula I + I - These are the peak reactive current and the peak negative sequence current, respectively. Let be the corresponding initial phase angle; neglecting the influence of higher harmonics, considering only the fundamental component, and setting the initial phase to 0, the switching function of each power sub-unit can be expressed as:

[0102] S i (t)=A i sinωt;

[0103] In the formula A i Let be the fundamental frequency component modulation ratio of the switching function of the i-th power sub-unit of phase a; combining the above formulas, we can obtain:

[0104]

[0105] From the above equation, it can be seen that the voltage of the power sub-unit capacitor includes a DC component and a harmonic AC component, where the harmonic AC component causes fluctuations in the voltage of the power sub-unit capacitor. Considering the average control of the phase unit capacitor voltage, the active power P of the upper arm... Pj and the active power P of the lower bridge arm Nj The sum of these values ​​yields the total active power absorbed by a single phase of the device.

[0106]

[0107] In the formula, I dcj For the DC component, i cj For AC side current, u dc To output DC voltage, u sj AC power supply; reference value U for power sub-unit capacitor voltage. c_ref The average value U of the capacitor voltage of a certain phase cj_avg Compare the DC component obtained from the device through the voltage regulator with the actual circulating current i. zj The error signal is passed through the current regulator to obtain the final average capacitor voltage regulation amount U. ref1 Actual circulation i zj From the upper bridge arm current i Pj and lower bridge arm current i Nj Calculation generation; i err This represents the error current; considering the capacitor voltage is a DC quantity, a PI controller can be used in the outer voltage loop to achieve error-free voltage tracking; considering that the device will cause circulating current i when compensating for negative sequence current. zj It includes DC components and frequency-doubled AC components, and the inner current loop uses a quasi-PR controller to achieve error-free tracking of the circulating current.

[0108] Furthermore, such as Figure 3 As shown, the upper and lower bridge arm capacitor voltage balance control includes:

[0109] Real-time acquisition of the sum of capacitor voltages of all power sub-units in the upper arm unit of each phase bridge arm;

[0110] Real-time acquisition of the sum of capacitor voltages of all power sub-units in the lower arm unit of the same phase bridge arm;

[0111] Calculate the active power difference between the sum of the capacitor voltages of the upper and lower bridge arms in phase.

[0112] When the active power difference exceeds the preset difference threshold, a bridge arm power allocation correction instruction is generated. The bridge arm power allocation correction instruction includes the power allocation ratio adjustment value between the upper bridge arm and the lower bridge arm.

[0113] Input the bridge arm power correction command into the charge / discharge regulation module;

[0114] The charge / discharge regulation module adjusts the power output time ratio of the upper and lower bridge arm units of the corresponding phase synchronously according to the power distribution ratio adjustment value.

[0115] As a preferred embodiment of the above, the active power P of the upper bridge arm is controlled by considering the voltage balance of the upper and lower bridge arm capacitors. Pj and the active power P of the lower bridge arm Nj Subtracting these values ​​yields the difference in active power absorbed by the upper and lower arms of a given phase:

[0116]

[0117] In the formula, i cPj Indicates the alternating current component of the upper bridge arm, i cNj Indicates the alternating current component of the upper bridge arm, u sj Let Δp be the AC power source; j =P Pj -P Nj ,Δi cj =i cPj -i cNj i cj =i cPj +i cNj Then we have:

[0118]

[0119] In the formula, i cj Indicates the overall AC current composition of the system; Δi cj Indicate i cj The increment; introducing an AC component, causing a DC component to be generated on the right side of the above equation. This DC component causes the upper bridge arm to absorb energy while the lower bridge arm releases energy, or vice versa, thereby balancing the capacitor voltages of the upper and lower bridge arms. Under the condition of compensating for unbalanced loads, the capacitor voltage will exhibit frequency doubling fluctuations. Therefore, the average voltage of the upper and lower bridge arms is filtered and then averaged. After being adjusted by a PI controller, it is multiplied by the grid frequency phase factor to obtain 1 / 2Δi. cj .

[0120] Furthermore, such as Figure 4 As shown, the common bus switching module performs bridge arm switching, including:

[0121] The common bus switching module corresponds to a phase selection switch for each bridge arm;

[0122] The bridge arm imbalance signal sent by the bridge arm balance control module is received. The bridge arm imbalance signal contains the identifier of the target power grid phase that needs to be switched.

[0123] Disconnect all currently connected bridge arm end switches, and simultaneously close the power input terminal, common bus terminal, and bridge arm end of the bus switch;

[0124] Close the phase selection switch corresponding to the target grid phase to connect the common bus to the target phase, and simultaneously open the phase selection switches for the other phases.

[0125] As a preferred embodiment of the above, the common bus switching module assigns a phase selection switch to each bridge arm. These switches can switch to different grid phases to achieve load balancing. A sensitive signal receiving mechanism is set up to receive the bridge arm imbalance signal sent by the bridge arm balancing control module. The bridge arm imbalance signal details the load imbalance problem that occurs in the current system operation and indicates the target grid phase identifier that needs to be switched. The advantage of this mechanism is that it can automatically adjust the phase according to the real-time grid load requirements when the bridge arm imbalance signal is transmitted in a timely manner. The first step of bridge arm switching is to disconnect all currently connected bridge arm end switches. The key to this step is to ensure that the system is not affected by transient instability caused by unexpected current impacts during the switching process. In the subsequent wiring steps, the common bus switching module synchronously closes the power input terminal, common bus terminal and bridge arm terminal of the bus switch, thereby ensuring the integrity and connection stability of the power transmission path after the new phase switch. Next, the common bus switching module, based on the target grid phase identifier conveyed in the bridge arm imbalance signal, correctly identifies the grid phase to be connected and closes the corresponding phase selection switch. In the preferred design, the phase selection switch uses a highly reliable electromagnetic operation or semiconductor switch to maintain high-speed switching and high durability during dynamic load changes. At the same time, the system control module automatically disconnects the phase selection switches of other phases, thereby avoiding unnecessary current vector interference caused by multi-phase parallel connection. In application scenarios, for example, if a charging station experiences an excessively high load on a specific phase due to ambient temperature or user demand at a certain moment, the common bus switching module can quickly identify the imbalance signal issued by the bridge arm balance control module and rapidly complete the grid phase switching to balance the output load. This rapid response effectively avoids equipment overload caused by prolonged excessive load and can also quickly optimize current regulation and power distribution between different load demands.

[0126] Furthermore, the switching control module includes:

[0127] Real-time acquisition of the effective value of the three-phase current of the power grid and the state of charge of the electric vehicle to be connected;

[0128] Compare the effective values ​​of the three-phase currents and identify the grid phase with the lowest load;

[0129] When multiple phase loads are close together, the target grid phase is selected based on the associated state of charge.

[0130] Generate a phase switching command containing the identifier of the target grid phase and output it to the common bus switching module.

[0131] As a preferred embodiment of the above, firstly, the switching control module is responsible for acquiring the effective values ​​of the three-phase currents of the power grid and the state of charge of the electric vehicle to be connected in real time, and monitoring the current status of each phase of the power grid in real time. In addition, the switching control module also needs to communicate with the electric vehicle on-board system to obtain the current state of charge information of its battery. This information can support dynamic load adjustment decisions. After collecting the relevant data, the switching control module performs a comparison between the effective values ​​of the three-phase currents to identify the power grid phase with the lowest load. Through the optimization algorithm, the system can quickly analyze and determine which power grid phase has the lowest load, so as to keep the overall load distribution of the power grid stable. When the three-phase load conditions are relatively similar, the module further selects the target power grid phase in combination with the state of charge of the electric vehicle. For example, if the loads of multiple phases are only slightly different, the system can associate and select the target phase based on the charging needs of the electric vehicle battery to ensure the maximum efficiency of power distribution and effective charging of the battery. When any two phases When the load differences are all less than a set threshold, the multi-phase loads are considered to be similar. At this time, the target phase is selected based on the state of charge of the power sub-unit. Once the target phase is determined, the switching control module generates a phase switching command containing the grid phase identifier of the target phase. In the preferred design, the command generator uses a fast-response microprocessor and software algorithm to ensure low-latency and efficient transmission. The generated phase switching command has clear phase identifier data. Subsequently, the command is output to the common bus switching module. After receiving the phase switching command, the common bus switching module performs a switching operation from the current load phase to the selected target phase, thereby realizing the optimized scheduling of grid load. In a preferred implementation scenario, for example, when multiple electric vehicles are queuing to charge at the same time in a charging station, the switching control module can quickly identify the load status of each phase and the charge level of each vehicle. When there is no significant difference in grid phase load, the system can prioritize the phase corresponding to the vehicle that still has a higher charging demand.

[0132] Example 2;

[0133] Based on the same inventive concept as the charging station resource scheduling system based on bridge arm balancing in the foregoing embodiments, the present invention also provides a charging station resource scheduling method based on bridge arm balancing, the method comprising:

[0134] Real-time acquisition of the effective value of the three-phase current of the power grid and the state of charge of the electric vehicle to be connected;

[0135] The target phase with the lowest load is identified based on the effective value of the three-phase current, and the target phase is determined by associating the state of charge when the multi-phase loads are similar.

[0136] Monitor the capacitor voltage of all power sub-units in each phase bridge arm;

[0137] Calculate the average voltage of the capacitor in each phase arm and the average voltage of the total three-phase capacitor;

[0138] When the deviation between the average value of the capacitor voltage of any phase arm and the average value of the total capacitor voltage exceeds the preset tolerance, a conduction time reallocation instruction for that phase power sub-unit is generated and executed.

[0139] The sum of the capacitor voltages of the upper and lower bridge arms in phase is obtained in real time, and the active power difference between the sum of the capacitor voltages of the upper and lower bridge arms is calculated.

[0140] When the difference in active power of any phase arm exceeds a preset threshold, the power output time ratio of the upper and lower arms of that phase is generated and adjusted synchronously.

[0141] The method described above in this invention can effectively realize a charging station resource scheduling system based on bridge arm balance, and the technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0142] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A charging station resource scheduling system based on bridge arm balancing, characterized in that, The system includes: Switching control module, charging and discharging regulation module, common bus switching module and bridge arm balance control module; The switching control module monitors the three-phase load status of the power grid corresponding to the charging station in real time, and generates a phase switching command when the unbalance exceeds the threshold. The common bus switching module receives the phase switching command and dynamically connects the charging station input side to the target power grid phase; The charge / discharge regulation module generates a modulation signal based on the power allocation command to control the switching timing of the power sub-units; The bridge arm balance control module includes a three-phase bridge arm circuit, which is used to convert the modulation signal into DC charging power, collect the current and capacitor voltage of each phase bridge arm in real time, generate a compensation signal according to the voltage deviation and feed it back to the charge and discharge regulation module to maintain the energy balance of the three-phase bridge arm circuit of the charging station. Each arm of the three-phase bridge arm circuit is composed of multiple power sub-units connected in series, and each power sub-unit can operate as the smallest unit for independent charging and discharging.

2. The charging station resource scheduling system based on bridge arm balancing according to claim 1, characterized in that, The three-phase bridge arm circuit is divided into an upper bridge arm unit and a lower bridge arm unit. Each phase bridge arm includes two in-phase and symmetrical upper bridge arm units and lower bridge arm units. The upper and lower bridge arm units of each phase bridge arm include a plurality of power sub-units and bridge arm smoothing reactances connected in series.

3. The charging station resource scheduling system based on bridge arm balancing according to claim 2, characterized in that, The power subunit includes: Switching device group, rectifier diode group, energy storage capacitor and resistor; The switching device group includes a first switching device and a second switching device, which switch the switching state according to the input control signal to regulate the current, and realize voltage rise and fall and current distribution based on alternating conduction and turn-off. The rectifier diode group includes a first diode and a second diode connected in parallel with the first switching device and the second switching device, respectively, for providing a unidirectional current flow path and performing a freewheeling operation when the switching device group is turned off; The energy storage capacitor is connected to the switching device group and the rectifier diode group to temporarily store energy and balance the power load and stabilize the output voltage when the load fluctuates. The resistor and the energy storage capacitor form an RC network, which is used to improve circuit stability, limit instantaneous overcurrent, and dissipate excess energy.

4. The charging station resource scheduling system based on bridge arm balancing according to claim 2, characterized in that, The bridge arm balance control module, when performing balancing, includes: The upper arm current of the upper arm unit and the lower arm current of the lower arm unit in each phase arm are collected respectively, and the real-time voltage of the energy storage capacitor in each power sub-unit is collected simultaneously. Calculate the absolute current difference between the upper bridge arm current and the lower bridge arm current, and the absolute voltage difference between the capacitor voltages of the power sub-units in phase. When the absolute current difference exceeds a preset current threshold, or the absolute voltage difference exceeds a preset voltage threshold, the compensation signal is generated. The compensation signal includes a phase compensation angle for adjusting the carrier phase and a quantity correction value for correcting the number of power sub-units switched. The compensation signal is input to the charge-discharge adjustment module, which corrects the phase offset of the carrier wave according to the phase compensation angle, and dynamically adjusts the number of power sub-modules put into operation in the upper bridge arm unit and the lower bridge arm unit according to the quantity correction value.

5. The charging station resource scheduling system based on bridge arm balancing according to claim 2, characterized in that, Average voltage control of each phase arm capacitor includes: The voltage of the energy storage capacitor of all power sub-units in each phase bridge arm is acquired in real time. Calculate the average capacitor voltage of each phase arm in the three-phase bridge arm circuit, and calculate the total average capacitor voltage of the three-phase bridge arm circuit based on the average capacitor voltage. When the deviation between the average value of the capacitor voltage of any phase bridge arm and the average value of the total capacitor voltage exceeds a preset tolerance, a switching timing adjustment command is generated. The switching timing adjustment command is sent to the charge / discharge regulation module; The charge / discharge regulation module reallocates the conduction time of the power sub-units of the phase bridge arm with excessive deviation according to the switching timing adjustment command, so that the average value of the capacitor voltage approaches the average value of the total capacitor voltage.

6. The charging station resource scheduling system based on bridge arm balancing according to claim 5, characterized in that, Upper and lower bridge arm capacitor voltage balance control, including: The sum of the capacitor voltages of all power sub-units in the upper arm unit of each phase arm is obtained in real time. The sum of the capacitor voltages of all power sub-units in the lower arm unit of the in-phase bridge arm is obtained in real time; Calculate the active power difference between the sum of the capacitor voltages of the upper and lower bridge arms in phase. When the active power difference exceeds a preset difference threshold, a bridge arm power allocation correction instruction is generated. The bridge arm power allocation correction instruction includes the power allocation ratio adjustment value between the upper bridge arm and the lower bridge arm. The bridge arm power correction command is input into the charge / discharge regulation module; The charge / discharge adjustment module synchronously adjusts the power output time ratio between the upper bridge arm unit and the lower bridge arm unit of the corresponding phase according to the power distribution ratio adjustment value.

7. The charging station resource scheduling system based on bridge arm balancing according to claim 1, characterized in that, The common bus switching module performs bridge arm switching, including: The common bus switching module corresponds to a phase selection switch for each bridge arm; The bridge arm imbalance signal sent by the bridge arm balance control module is received, and the bridge arm imbalance signal contains an identifier of the target power grid phase that needs to be switched. Disconnect all currently connected bridge arm end switches, and simultaneously close the power input terminal and common bus terminal of the bus switch with the bridge arm end; Close the phase selection switch corresponding to the target power grid phase, connect the common bus to the target phase, and simultaneously disconnect the phase selection switches for the other phases.

8. The charging station resource scheduling system based on bridge arm balancing according to claim 1, characterized in that, The switching control module includes: Real-time acquisition of the effective value of the three-phase current of the power grid and the state of charge of the electric vehicle to be connected; The effective values ​​of the three-phase currents are compared and the grid phase with the lowest load is identified to select the target grid phase; When multiple phase loads are close together, the target grid phase is selected by associating the state of charge. Generate the phase switching command containing the identifier of the target power grid phase and output it to the common bus switching module.

9. A charging station resource scheduling method based on bridge arm balancing, characterized in that, The method includes: Real-time acquisition of the effective value of the three-phase current of the power grid and the state of charge of the electric vehicle to be connected; Based on the effective value of the three-phase current, the target phase with the lowest load is identified, and when the multi-phase loads are similar, the target phase is determined by associating the state of charge. Monitor the capacitor voltage of all power sub-units in each phase bridge arm; Calculate the average voltage of the capacitor in each phase arm and the average voltage of the total three-phase capacitor; When the deviation between the average value of the capacitor voltage of any phase arm and the average value of the total capacitor voltage exceeds a preset tolerance, a conduction time reallocation instruction for the power sub-unit of that phase is generated and executed. The sum of the capacitor voltages of the upper and lower bridge arms in phase is acquired in real time, and the active power difference between the sum of the capacitor voltages of the upper and lower bridge arms is calculated. When the difference in active power of any phase arm exceeds a preset threshold, the power output time ratio of the upper and lower arms of that phase is generated and adjusted synchronously.

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