Mobile megawatt three-level busbar power distribution system and method based on DC 800V primary direct current busbar

Abstract

This invention provides a mobile megawatt-level three-stage combiner and distribution system and method based on a DC 800V primary DC bus, relating to the fields of mobile energy storage and power electronic distribution technology. The system employs a three-stage architecture: a primary high-voltage combiner, a secondary DC main combiner, and a tertiary terminal DC distribution system, coupled with AC and DC terminal combiner and distribution modules, to achieve power combiner, conversion, and distribution. This invention utilizes a single combiner node architecture on a DC 800V common DC main bus, simplifying the energy transmission link, reducing AC / DC conversion stages, and improving system energy efficiency. Simultaneously, a dedicated parallel control method is implemented to suppress high-voltage energy storage parallel inrush current, ensuring stable bus voltage. Combined with a dynamic power allocation algorithm, real-time closed-loop control of fast charging power is achieved, adapting to dynamic fluctuations under multiple operating conditions, significantly improving power utilization, reducing equipment size and weight, and meeting the mobile deployment requirements of mobile platforms.

Description

Technical Field

[0001] This invention relates to the field of mobile energy storage and power electronic distribution technology, and in particular to a mobile megawatt-level three-level bus distribution system and method based on a DC 800V primary DC bus. Background Technology

[0002] With the rapid popularization of new energy vehicles and the continuous growth in demand for motorized power supply in scenarios such as large-scale emergency support and field operations, mobile megawatt-level power distribution systems that integrate energy storage, AC power supply, and DC fast charging have become an important equipment direction in the field of power security. Such systems are usually carried by special vehicles and require the integration of large-capacity energy storage battery packs (total capacity is usually in the range of 1MWh to several MWh), high-power power conversion equipment (rated power is usually in the range of 1MW to several MW), and multi-functional power distribution devices within a limited vehicle space. They also need to be able to be quickly deployed and put into use after being transported by motor, which places extremely high demands on system integration, efficiency, and reliability.

[0003] In existing technologies, the mainstream architecture of mobile energy storage charging vehicles typically adopts an AC-coupled topology. In this architecture, external grid power is stepped down by the on-board power frequency transformer and then rectified and charged by the power conversion systems (PCS) of each energy storage unit. When supplying power to external systems, each energy storage unit is inverted by its respective PCS and then fed into the on-board AC bus for output. For DC fast charging output, the AC bus power needs to be rectified again by a dedicated charging module before it can be used. In the above architecture, the energy flow for DC fast charging output is: energy storage battery → PCS inversion → AC bus → charging module rectification → DC fast charging interface, with the energy undergoing at least three AC-DC conversions. At megawatt-level power scales, the loss per conversion is approximately 2% to 4%, and the accumulated conversion losses result in ineffective heat dissipation of tens or even hundreds of kilowatts, severely restricting the system's energy efficiency and exacerbating the heat dissipation pressure inside the vehicle.

[0004] At the same time, the superposition of multiple independent PCS and power frequency transformers occupies a large amount of vehicle space and load-bearing weight, which restricts the maximum battery loading capacity under the same chassis, thereby limiting the system's energy storage capacity and range, and is not conducive to the requirements of lightweight and high integration of mobile platforms.

[0005] In terms of control technology for multiple large-capacity energy storage units connected to a DC bus, existing systems generally face the engineering challenge of parallel inrush current. When multiple large-capacity battery packs with capacities in the hundreds of ampere-hours are connected to the same DC bus with differences in their terminal voltages, the peak value of the transient inrush current generated in the DC connection circuit is proportional to the difference in terminal voltages between the battery packs and inversely proportional to the equivalent impedance of the circuit. Under a DC 800V high-voltage platform, to ensure controllable conductor heat generation, the DC connection circuit typically uses low-impedance copper busbars with large cross-sectional areas, resulting in a relatively small equivalent impedance. Even if the terminal voltages of the battery packs differ by only a few volts, the peak inrush current can reach hundreds or even thousands of amperes. This can easily cause the main circuit breaker to withstand short-term overcurrent surges far exceeding its rated value without sufficient preheating. This can lead to minor protective tripping errors or, in severe cases, oxidation, adhesion, or even damage to the contacts of the main circuit breaker during high-current arcing, and cause serious disturbances to the instantaneous stability of the DC 800V common DC main bus voltage. While existing technologies include pre-charging circuit designs for parallel connection of single battery groups, there is no systematic technical disclosure on how to quantitatively determine the parallel connection sequence and voltage equalization threshold when multiple large-capacity batteries are connected in parallel under DC800V high voltage on a mobile platform.

[0006] In terms of multi-channel DC fast charging power management, existing mobile energy storage charging systems typically adopt a static power configuration mode, which pre-allocates a fixed maximum output power quota to each charging gun. Each channel operates independently without dynamic allocation. This mode results in a large amount of unused power resources when the number of charging guns connected is small, or when the charging power demand of the receiving equipment is far below the quota, leading to low overall fast charging power utilization. Furthermore, when some charging guns are disconnected due to interface failure, the static configuration mode cannot automatically redistribute the power quota of the faulty guns to the remaining normal guns, further reducing the actual output efficiency of the system.

[0007] In view of this, there is an urgent need for a mobile megawatt-level three-stage busbar distribution system and method based on a DC 800V primary DC bus, in order to at least solve the above-mentioned shortcomings. Summary of the Invention

[0008] One of the objectives of this invention is to provide a mobile megawatt-level three-stage busbar distribution system and method based on a DC 800V primary DC bus, in order to solve the problems pointed out in the background art.

[0009] The mobile megawatt-level three-stage busbar distribution system based on a DC 800V primary DC bus provided in this embodiment of the invention includes: The first-level high-voltage combiner module is used to convert external medium- and high-voltage AC power through a bidirectional power conversion unit, and output the converted DC 800V DC power to the DC 800V common DC main bus. The secondary DC main bus module is used to connect all N energy storage units in the system to the DC800V common DC main bus through their respective independent DC access circuits, so that the DC800V common DC main bus becomes the only common bus node for DC power exchange between all energy storage units and bidirectional power conversion units in the system. The three-level terminal DC distribution module is used to stabilize the DC power collected by the DC800V common DC main bus and shunt the current through the DC voltage regulation and shunt unit, and output it to the first and second terminal power distribution circuits that are electrically independent of each other. The AC terminal power distribution module is used to convert the DC power of the first terminal power distribution circuit into AC power through the inverter unit, and to aggregate and manage it with the external AC backup power supply at the dual power supply automatic switching unit. It automatically selects the priority power supply according to the availability of the external AC backup power supply and outputs it to the AC load in a unified manner. The DC terminal power distribution module is used to separately combine the DC power of the second terminal power distribution circuit to the DC fast charging power distribution unit, and after internal hierarchical protection and power distribution, independently distribute it to multiple DC fast charging output interfaces for external output.

[0010] Preferably, the primary high-voltage combiner module performs the following operations: External medium- and high-voltage AC power in the range of 6kV to 35kV is connected to the high-voltage input side of the bidirectional power conversion unit via the high-voltage incoming line protection unit; The bidirectional power conversion unit performs high-frequency isolation rectification on medium and high voltage AC power through built-in wide bandgap semiconductor power devices, converting medium and high voltage AC power into DC 800V DC power that matches the nominal total voltage level of the N groups of energy storage units in the system. The converted DC 800V DC power is output to the DC 800V common DC main bus. When the energy storage unit needs to feed energy back to the external power grid, the bidirectional power conversion unit is controlled to operate in reverse, converting the DC power on the DC 800V common DC main bus into medium- and high-voltage AC power and outputting it to the external power grid through the high-voltage incoming line protection unit.

[0011] Preferably, the secondary DC main bus module performs the following operations: Each energy storage unit is equipped with an independent DC access circuit, and a pre-charge current limiting branch and a main circuit circuit breaker are connected in series in the DC access circuit. Before each energy storage unit is connected in parallel to the DC800V common DC main bus, the corresponding energy storage unit is first subjected to voltage equalization and current limiting processing through the pre-charge current limiting branch; the terminal voltage of the energy storage unit and the real-time voltage of the DC800V common DC main bus are collected by their respective voltage monitoring units. After the difference between the terminal voltage and the DC800V common DC main bus voltage is less than the preset voltage equalization threshold, the corresponding main circuit breaker is closed to complete the parallel connection and eliminate the parallel inrush current. After the parallel connection is completed, the current of each energy storage unit branch is continuously monitored by the current monitoring unit set in each DC access circuit. When the current of any branch exceeds the overcurrent protection action threshold of the corresponding branch, the corresponding main circuit circuit breaker is independently disconnected to achieve single-group fault isolation, and the remaining energy storage units and DC800V common DC main bus maintain normal operation.

[0012] Preferably, the three-level terminal DC distribution module performs the following operations: The DC800V common DC main bus voltage is collected in real time. When the DC800V common DC main bus voltage fluctuates within the preset voltage fluctuation range due to the change in the state of charge of the energy storage unit, the DC voltage regulation and shunt unit adjusts the control parameters of the internal power devices to keep the output voltage of the first end distribution circuit and the second end distribution circuit stable within the preset deviation range of their respective rated values. The current direction monitoring unit of the corresponding circuit detects the current conduction direction in the first and second terminal power distribution circuits respectively. When the reverse conduction of current from the load side to the DC800V common DC main bus is detected in either terminal power distribution circuit, the electrical connection between the corresponding circuit and the DC800V common DC main bus is cut off to prevent the fault from spreading to the main bus level. When the system starts up or the end load is connected, soft start slope control is performed on the output current of the first end power distribution circuit and the second end power distribution circuit respectively, limiting the rise rate of the output current to within a preset value, and suppressing the disturbance of the power-on impact on the stability of the DC800V common DC main bus voltage.

[0013] Preferably, the AC terminal busbar distribution module performs the following operations: The dual-power automatic switching unit continuously monitors the voltage amplitude, frequency, and phase sequence of the external AC backup power supply to determine whether the external AC backup power supply is in a qualified and usable state. When the external AC backup power supply is in a qualified and available state, the dual power automatic switching unit will switch the AC output of the inverter unit to the standby state and give priority to using the external AC backup power supply to supply power to the AC load. When the external AC backup power supply fails or its parameters exceed the acceptable range, the dual power supply automatic switching unit automatically switches to the AC output of the inverter unit within a preset switching time to continuously supply power to the AC load. The power interruption time during the switching process does not exceed the preset interruption time threshold.

[0014] Preferably, the DC terminal busbar distribution module performs the following operations: The DC fast charging power distribution unit obtains the charging request power and rated voltage of the power receiving platform of the power receiving equipment connected to each DC fast charging output interface in real time through the DC fast charging communication protocol. The DC fast charging power distribution unit collects the real-time bus current and real-time bus voltage of the DC800V common DC main bus in real time, calculates and determines the current total power limit that the system can allocate to the DC fast charging side; based on the total power limit and the charging request power of the powered devices connected to each DC fast charging output interface, it dynamically calculates and allocates the output power of each DC fast charging output interface according to the power allocation strategy determined based on the relationship between the charging request power of each channel and the total power limit, so that the sum of the output power of each channel does not exceed the total power limit; Each DC fast charging output interface is independently deployed and continuously implemented with output overcurrent protection, short circuit protection, and insulation fault detection. When any interface triggers any protection action condition, the output of the corresponding interface is independently cut off. After the faulty interface is eliminated, the power distribution calculation is re-executed and the remaining interfaces continue to output normally.

[0015] Preferably, the execution sequence of connecting each group of energy storage units in parallel to the DC 800V common DC main bus is determined as follows: Using the real-time voltage of the DC800V common DC main bus as a reference, the N groups of energy storage units are sorted in ascending order of the difference between their respective terminal voltage and the real-time voltage of the DC800V common DC main bus. The pre-charge equalization parallel connection of each group of energy storage units is performed in ascending order of the difference. Between the parallel connection operations of two adjacent groups, the pre-charge equalization parallel connection operation of the next group is performed only after the DC800V common DC main bus voltage has stabilized back to the preset voltage stability range.

[0016] Preferably, the total power limit is calculated in real time using the following formula: ; in, This is the upper limit of total power. This refers to the real-time voltage of the DC 800V common DC main bus. This represents the real-time current of the busbar. This refers to the power ratio coefficient on the DC fast charging side. The current power consumption of other loads in the system is calculated by multiplying the output current and output voltage of the first terminal power distribution circuit in real time. Among them, the power ratio of DC fast charging side The following rules will be dynamically adjusted: When the system is only operating the DC terminal busbar distribution module Take the preset maximum value; When the system operates both the AC terminal combiner and the DC terminal combiner, priority is given to ensuring the power supply requirements of the AC load in the AC terminal combiner, and the remaining power after ensuring the AC load is fully allocated to the DC fast charging side. When the real-time voltage of the DC800V common DC main bus is lower than the preset low-voltage threshold... As the real-time bus voltage decreases, it decreases linearly according to the preset derating curve, so that the total power limit is reduced smoothly, preventing the real-time bus voltage from dropping further due to excessive load on the DC fast charging side.

[0017] Preferably, after each triggering of power allocation re-execution, the output power of each DC fast charging output interface is smoothly adjusted to the corresponding target allocation power at a rate not exceeding the preset power adjustment slope; when the real-time voltage deviation of the DC800V common DC main bus exceeds the preset bus voltage stability threshold during the adjustment process, the power increase adjustment of all interfaces is suspended first, and the unfinished power increase adjustment is continued after the real-time voltage of the DC800V common DC main bus recovers to the preset bus voltage stability range.

[0018] The mobile megawatt-level three-stage busbar distribution method based on a DC 800V primary DC bus provided in this embodiment of the invention includes: Step 1: The external medium- and high-voltage AC power is bidirectionally converted by the bidirectional power conversion unit, and the converted DC 800V DC power is uniformly output to the DC 800V common DC main bus. Step 2: Connect all N energy storage units in the system to the DC 800V common DC main bus through their respective independent DC access circuits, so that the DC 800V common DC main bus becomes the only common junction node for DC power exchange between all energy storage units and bidirectional power conversion units in the system. Step 3: The DC power collected by the DC800V common DC main bus is regulated and current is shunted by the DC voltage regulation and shunting unit, and then output to the first and second terminal power distribution circuits which are electrically independent of each other. Step 4: Convert the DC power of the first terminal distribution circuit into AC power through the inverter unit, and then combine and manage it with the external AC backup power supply at the dual power supply automatic switching unit. Based on the availability of the external AC backup power supply, the priority power supply is automatically selected and output to the AC load in a unified manner. Step 5: The DC power from the second terminal power distribution circuit is separately fed into the DC fast charging power distribution unit, and after internal hierarchical protection and power distribution, it is independently distributed to multiple DC fast charging output interfaces for external output.

[0019] The beneficial effects of this invention are as follows: This invention replaces the power frequency AC bus in the traditional AC-coupled architecture with a DC 800V common DC main bus, reducing the energy flow of DC fast charging output to: energy storage battery → DC 800V common DC main bus → DC fast charging distribution unit → DC fast charging interface. Compared to the traditional three-stage conversion architecture, this reduces two unnecessary AC-DC conversions. At megawatt-level power scales, it significantly improves system energy efficiency and vehicle cooling capacity.

[0020] This invention uses a DC 800V common DC main bus as the only common combiner node of the system, enabling multiple energy storage units and bidirectional power conversion units to share the same DC access level. This eliminates the need for redundant configuration of multiple PCS devices and power frequency transformers in the AC coupling architecture, effectively reducing the number of system devices, wiring complexity, and overall weight and volume, and enhancing the integration and mobile deployment capabilities of the mobile platform.

[0021] This invention addresses the inrush current problem of multiple large-capacity batteries connected in parallel under DC800V high voltage on mobile platforms. It proposes a sequential parallel control method based on the order of terminal voltage differences for pre-charging and voltage equalization of each battery group. This method fundamentally constrains the inrush current at the moment the main circuit breaker closes within a preset safety range, solving the problem of the lack of systematic parallel control logic for DC800V high-voltage and large-capacity scenarios in existing technologies. This significantly improves the system's startup reliability and DC bus voltage stability.

[0022] This invention proposes a real-time calculation formula for the total power limit based on real-time bus sampling. Combined with a multi-mode dynamic adjustment mechanism for the power proportion coefficient of the DC fast charging side and a closed-loop redistribution algorithm with multiple trigger conditions, it elevates the power management of multiple DC fast charging lines from a static quota mode to a real-time closed-loop dynamic management level. The system can automatically recalculate and optimize the allocation of charging power for each line under various dynamic operating conditions, such as changes in the number of charging guns, changes in the demand of powered equipment, fluctuations in AC load, or changes in bus voltage. This maximizes the total power utilization rate of the fast charging side and prevents disturbances to the stability of the DC800V common DC main bus voltage during the redistribution process through power smoothing slope control.

[0023] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in this application.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of a mobile megawatt-level three-stage busbar distribution system based on a DC 800V primary DC busbar in an embodiment of the present invention; Figure 2 This is a schematic diagram of a mobile megawatt-level three-stage busbar distribution method based on a DC 800V primary DC bus in an embodiment of the present invention. Detailed Implementation

[0026] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0027] This invention provides a mobile megawatt-level three-stage busbar distribution system based on a DC 800V primary DC bus, such as... Figure 1 As shown, it includes: The first-level high-voltage combiner module 1 is used to convert external medium- and high-voltage AC power through a bidirectional power conversion unit, and output the converted DC 800V DC power to the DC 800V common DC main bus.

[0028] The core function of the primary high-voltage combiner module is to achieve efficient bidirectional power conversion between the external medium- and high-voltage AC power grid and the DC 800V common DC main bus, and to provide necessary electrical isolation and incoming line protection.

[0029] External 6kV to 35kV medium-high voltage AC power is connected to the high-voltage input side of the bidirectional power conversion unit via the high-voltage incoming line protection unit. The high-voltage incoming line protection unit typically includes a high-voltage circuit breaker and surge protection device, used to quickly disconnect from the power grid in case of external power grid anomalies or internal system faults, protecting the safety of system equipment.

[0030] The bidirectional power converter integrates wide-bandgap semiconductor power devices such as silicon carbide MOSFETs, employing a dual-active-bridge converter topology to achieve high-frequency isolation conversion between the high-voltage side and the DC 800V DC side at mid-to-high frequencies (not lower than 20kHz). In charging mode, the bidirectional power converter rectifies and converts the mid-to-high voltage AC power into DC 800V DC power, which is then fed into the DC 800V common DC main bus and shunted through the DC access circuits of each energy storage unit to charge each battery group. In feedback mode, the bidirectional power converter operates in reverse, inverting and boosting the DC power on the DC 800V common DC main bus into mid-to-high voltage AC power synchronized with the external power grid in frequency and phase, which is then fed back to the external power grid via the high-voltage incoming line protection unit.

[0031] The core advantage of high-frequency isolation transformers over traditional power frequency transformers lies in their significant reduction in size and weight. The cross-sectional area of ​​a power frequency transformer core is approximately inversely proportional to its operating frequency. When operating with a DAB topology at frequencies above 20kHz, the transformer core volume can be reduced to about one-hundredth of that of a power frequency solution. At the megawatt-level power rating, this reduction significantly improves the overall vehicle weight and space layout, making it one of the key enabling technologies for achieving high integration in megawatt-level mobile platforms.

[0032] The secondary DC main bus module 2 is used to connect all N groups of energy storage units in the system to the DC800V common DC main bus through their respective independent DC access circuits, so that the DC800V common DC main bus becomes the only common bus node for DC power exchange between all energy storage units and bidirectional power conversion units in the system.

[0033] The core function of the secondary DC main bus module is to safely and reliably connect all N (N≥2) energy storage units in the system into the DC800V common DC main bus, and continuously monitor the status of each branch during operation to achieve rapid and independent isolation of single-unit faults.

[0034] Each energy storage unit is equipped with an independent DC access circuit. Each DC access circuit consists of a pre-charge current-limiting branch (including a current-limiting resistor and a pre-charge contactor), a main circuit breaker, a voltage monitoring unit, and a current monitoring unit connected in series. Initially, the main circuit breakers of all N energy storage units remain open.

[0035] When the main circuit breaker of a certain energy storage unit is closed, if there is a voltage difference between the terminal voltage of the energy storage unit and the DC 800V common DC main bus voltage, a peak inrush current will be generated in the DC access circuit at the moment the circuit breaker closes. This peak value is proportional to the voltage difference and inversely proportional to the total impedance of the circuit (i.e., the sum of the bus equivalent internal resistance and the line impedance).

[0036] Under the actual engineering parameters of the DC 800V high-voltage platform, to ensure controllable conductor heat generation during full-load operation, the DC input circuit uses a low-impedance copper busbar with a cross-sectional area of ​​1000mm², whose conductor resistance is approximately 0.02mΩ / m. The typical circuit length is about 5m. Combined with the on-resistance of the main circuit breaker and contactor, the typical line impedance is approximately 0.5mΩ to 2mΩ; the equivalent internal resistance of the busbar is approximately 0.1mΩ to 0.5mΩ, and the typical total circuit impedance is approximately 0.6mΩ to 2.5mΩ. Due to the extremely low total circuit impedance, even if the voltage difference between the battery terminals is only a few volts, the peak inrush current can easily exceed several thousand amperes. For example, with a typical parameter of 5V terminal voltage difference and a total circuit impedance of 1mΩ, the peak inrush current reaches as high as 5000A. Although this inrush current lasts only a few milliseconds, it is sufficient to cause arc erosion and accelerated wear of the main circuit breaker contacts, even leading to contact adhesion, and severely disrupting the voltage stability of the DC 800V common DC main bus.

[0037] In this embodiment of the invention, multiple energy storage units are connected in parallel to the DC 800V common DC main bus and controlled by sequential pre-charging and voltage equalization.

[0038] The core of the sequential parallel control method of this invention lies in reducing the difference between the terminal voltage of the energy storage unit and the DC 800V common DC main bus voltage to a preset voltage equalization threshold before the main circuit breaker of any group of energy storage units is closed. Therefore, the peak inrush current when the circuit breaker closes is constrained to the preset maximum allowable inrush current. Within this range. Simultaneously, the parallel operation of N groups of energy storage units is performed sequentially in a specific order. After each group is completed, the bus voltage is allowed to stabilize before proceeding to the next group.

[0039] The specific implementation steps are as follows: Before the system is put into operation, the power distribution control unit calculates and sets the preset voltage equilibration threshold according to the pre-stored system parameters using the following formula. : ; in, The maximum allowable parallel inrush current of the system is determined by the system engineer based on the contact life of the main circuit breaker, the rated making current of the contactor, and the DC800V common DC main bus voltage disturbance tolerance. The equivalent internal resistance of the DC 800V common DC main bus; This refers to the line impedance of the corresponding DC access circuit (including the sum of the copper busbar resistance, circuit breaker on-resistance, and contactor on-resistance).

[0040] Taking the engineering parameters of this embodiment as an example: Calibration The total circuit impedance is approximately 1.5mΩ. Substituting this into the above formula, we get... That is, the corresponding main circuit breaker can only be closed when the difference between the terminal voltage of a certain energy storage unit and the DC 800V common DC main bus voltage drops below 0.75V.

[0041] The power distribution control unit collects the current terminal voltage of all N groups of energy storage units through the voltage monitoring units corresponding to each group of energy storage units. Using the real-time voltage of the DC 800V common main DC bus as a reference, it calculates the difference between the terminal voltage of each group of energy storage units and the bus voltage, and sorts them in ascending order of difference to form a parallel priority queue. The energy storage unit with the terminal voltage closest to the bus voltage is placed at the head of the queue and performs parallel operation first. The energy storage unit with the smallest terminal voltage difference meets the requirements most quickly after the limited pre-charge equalization time of the pre-charge current-limiting branch. This constraint allows for the fastest possible parallel connection, enabling the DC 800V common DC main bus to quickly obtain voltage support from the first group of energy storage units, thus providing a more stable voltage reference for subsequent parallel operations.

[0042] According to the sorted queue, perform the following sequence of operations on each group of energy storage units in turn: First, close the pre-charge contactor corresponding to the energy storage unit group to establish a current-limited electrical connection between the energy storage unit group and the DC800V common DC main bus through the current-limiting resistor; the current-limiting resistor limits the peak value of the pre-charge current to a safe range (usually not exceeding 20% ​​of the rated charging current), and the terminal voltage of the energy storage unit group then gradually approaches the bus voltage.

[0043] Secondly, the power distribution control unit continuously reads the terminal voltage of the energy storage unit and the real-time voltage of the DC800V common DC main bus output by the voltage monitoring unit at a sampling frequency of not less than 1000Hz, and calculates and updates the difference between the two in real time.

[0044] Then, when the difference is detected to be less than When the power distribution control unit determines that the energy storage unit has met the conditions for parallel connection without impact, it immediately closes the corresponding main circuit circuit breaker while keeping the pre-charge contactor closed, thus completing the parallel connection of the energy storage unit.

[0045] Finally, after the main circuit breaker is closed, the pre-charge contactor immediately opens, the pre-charge current-limiting resistor exits the circuit, and the energy storage unit enters the formal parallel operation state.

[0046] After each set of energy storage units is connected in parallel, the power distribution control unit continuously monitors the real-time voltage of the DC800V common DC main bus. Once the voltage stabilizes again within the preset voltage stability range (e.g., ±0.5% of the rated value), the next set of energy storage units is taken out from the queue, and the pre-charge equalization parallel operation sequence is repeated until all N sets of energy storage units are connected in parallel.

[0047] The mandatory stability waiting interval set between two adjacent parallel operations is of significant engineering importance. Even after each new energy storage unit is connected in parallel, its terminal voltage must still meet the voltage requirements of the DC 800V common DC main bus. Due to constraints, a limited inrush current will still be injected into the busbar at the moment the circuit breaker closes, causing a minor disturbance to the busbar voltage. If the next parallel operation is executed immediately before the busbar voltage stabilizes, the cumulative effect of multiple disturbances may cause the busbar voltage to deviate from the preset voltage stability range. This could lead to the overcurrent protection of the branch current monitoring unit of the already paralleled energy storage unit being falsely triggered, resulting in the false tripping and isolation of the already paralleled energy storage unit. The stabilization waiting mechanism effectively avoids the above-mentioned cascading failure risk.

[0048] Taking N=4 energy storage units in this embodiment as an example, the estimated time required to complete the sequential parallel connection of all 4 energy storage units according to the method of this invention is as follows: the pre-charging and equalization time for each group is approximately 3 to 10 seconds (depending on the initial magnitude of the terminal voltage difference and the resistance value of the current limiting resistor), the bus voltage stabilization waiting time is approximately 1 to 3 seconds, and the total sequential parallel connection time is approximately 16 to 52 seconds. The above times are completely acceptable for the field deployment process of mobile megawatt-level systems and are far superior to the time spent on equipment inspection and maintenance after traditional high-current surges.

[0049] After all N energy storage units are connected in parallel, the power distribution control unit continuously reads the real-time current values ​​of the current monitoring units in each DC input circuit at a sampling frequency of no less than 1000Hz. The current monitoring units use Hall effect current sensors with a wide frequency response from DC to several kilohertz, which can accurately capture impulse overcurrent events.

[0050] The power distribution control unit continuously compares the current value of each branch with the overcurrent protection threshold corresponding to that branch. The overcurrent protection threshold is calibrated based on the rated charging and discharging current of each energy storage unit and the rated current of the main circuit breaker, with a safety factor of not less than 120% of the rated value. When the current in any branch exceeds the corresponding overcurrent protection threshold and the duration exceeds the preset delay (usually 5ms to 20ms to filter out normal current fluctuations), the power distribution control unit immediately issues a trip command to the corresponding main circuit breaker, independently disconnecting the electrical connection between that energy storage unit and the DC 800V common DC main bus, thus achieving single-group fault isolation. The DC access circuits of the remaining N-1 energy storage units are unaffected, and the DC 800V common DC main bus resumes stable operation within approximately tens of milliseconds after the fault group isolation is completed.

[0051] After a single energy storage unit fails and is isolated, the system's total power capacity is reduced accordingly. After completing the fault isolation, the power distribution control unit will recalculate the total power capacity that the DC 800V common main bus can sustainably output, based on the actual available capacity and current state of charge of the remaining N-1 normally operating energy storage units. This updated value will then be transmitted to the DC fast-charging power distribution unit, which will use the updated parameter values ​​in subsequent total power capacity calculations. This ensures the system continues to operate stably under derating conditions and avoids cascading failures caused by excessive power extraction from the remaining energy storage units.

[0052] The three-level terminal DC distribution module 3 is used to stabilize the DC power collected from the DC800V common DC main bus through the DC voltage regulation and current shunting unit, and output it to the first and second terminal power distribution circuits that are electrically independent of each other.

[0053] The core function of the three-level terminal DC distribution module is to reliably distribute the DC power collected by the DC800V common DC main bus to two electrically independent terminal distribution circuits, and to complete voltage regulation, reverse current protection and soft start control during the distribution process.

[0054] The DC voltage regulation and shunt unit acquires the DC 800V common DC main bus voltage in real time. Because the state of charge (SOC) of each energy storage unit continuously changes during charging and discharging, the DC 800V common DC main bus voltage fluctuates continuously within the system design's allowable range (typically 720V to 840V in this embodiment, corresponding to the SOC of each lithium iron phosphate battery pack ranging from approximately 10% to 100% of its full state of charge). The DC voltage regulation and shunt unit internally employs a wide input voltage range DC / DC converter topology (such as a phase-shifted full-bridge or LLC resonant converter). By adjusting the control parameters of the power devices in real time (such as duty cycle or resonant parameters), it actively compensates for the impact of bus voltage fluctuations, stabilizing the output voltages of the first and second terminal distribution circuits within their respective preset deviation ranges of their rated values ​​(calibrated in this embodiment to be within ±2% of the rated value). This voltage stabilization function ensures that the input voltage of the terminal AC inverter unit and DC fast charging distribution unit is always within their respective normal operating range, avoiding the risk of undervoltage protection activation of the terminal equipment when the bus voltage is too low, or overvoltage damage to the terminal equipment when the bus voltage is too high.

[0055] Regarding reverse current protection, the current direction monitoring unit of the corresponding circuit continuously detects the current conduction direction in the first and second terminal distribution circuits. Under normal operating conditions, the current direction in both distribution circuits flows from the DC800V common DC main bus to the terminal load. When reverse current is detected in either distribution circuit (i.e., conduction from the load side to the DC800V common DC main bus), the distribution control unit determines that an abnormality has occurred in the corresponding terminal circuit, immediately disconnects the electrical connection between the corresponding circuit and the DC800V common DC main bus, isolates the fault at the terminal distribution level, and prevents it from spreading to other modules through the DC800V common DC main bus.

[0056] Regarding soft-start control, when the system is first powered on or when a terminal load is connected, the DC voltage regulation and shunt unit performs adjustable-slope soft-start control on the output current of the first and second terminal power distribution circuits, respectively. Within a preset soft-start time window (calibrated to 200ms to 500ms in this embodiment), the output current linearly climbs from 0 to the rated output current at a preset slope, limiting the peak power-on inrush current to within 150% of the rated value, effectively suppressing disturbances to the stability of the DC800V common DC main bus voltage when large capacitive or inductive loads are suddenly connected.

[0057] The AC terminal power distribution module 4 is used to convert the DC power of the first terminal power distribution circuit into AC power through the inverter unit, and to aggregate and manage it with the external AC backup power supply at the dual power supply automatic switching unit. It automatically selects the priority power supply according to the availability of the external AC backup power supply and outputs it to the AC load in a unified manner.

[0058] The core function of the AC terminal busbar distribution module is to enable rapid switching between the system's own inverter power supply and the external AC backup power supply based on the dual power supply automatic switching mechanism, so as to provide continuous and stable AC power to the AC load.

[0059] The DC power from the first terminal distribution circuit is converted into AC power at the rated frequency (50Hz) and rated voltage (e.g., three-phase 380V / single-phase 220V) by the inverter unit. The inverter unit has a built-in phase-locked loop (PLL) and closed-loop control of the output voltage, ensuring that the frequency deviation of the output AC voltage does not exceed ±0.2Hz and the voltage deviation does not exceed ±2% of the rated value, meeting the power supply quality requirements of general industrial and civil electrical equipment.

[0060] The dual-power automatic transfer unit continuously monitors the three-phase voltage amplitude, frequency, and phase sequence of the external AC backup power supply at a sampling frequency of no less than 100Hz. Qualification criteria typically include: each phase voltage amplitude within ±15% of its rated value, the frequency within ±2Hz of its nominal value, and the correct phase sequence. When the external AC backup power supply meets all qualification criteria, the dual-power automatic transfer unit switches the inverter unit's AC output to standby mode, prioritizing power supply to the AC load from the external AC backup power supply. This reduces unnecessary energy consumption by the system's energy storage unit and extends its operating range.

[0061] The inverter unit does not completely shut down while powered by an external AC backup power supply. Instead, it continuously operates in a tracking-synchronous standby mode: its internal power circuit and controller remain energized, the phase-locked loop continuously locks onto and tracks the output voltage waveform of the external AC backup power supply, and adjusts the phase and amplitude of the inverter unit's own output voltage in real time to maintain the phase difference within 5° and the amplitude deviation within 2% of the rated value. The inverter unit's AC output is isolated from the AC load through the switching contacts in the dual-power automatic switching unit, and does not output current to the AC load during tracking-synchronous standby, thus not affecting the normal power supply of the external power source.

[0062] When the external AC backup power supply fails or any of its electrical parameters exceeds the acceptable range, the dual-power automatic switching unit detects the power failure event and immediately sends an action command to the switching contacts. Since the inverter unit is already in a tracking synchronization standby state with real-time phase synchronization with the external power supply, after the switching contacts are activated, the inverter unit can immediately supply power to the AC load with a near-zero phase difference, without needing to re-establish the output voltage waveform. This allows for a seamless switching from the external power supply to the inverter unit within a preset switching time (calibrated to no more than 20ms in this embodiment), with the power interruption time not exceeding the preset interruption time threshold. The 20ms switching time is shorter than the minimum tolerance time for power interruption for most industrial control and IT equipment (typically 20ms to 50ms), enabling near-uninterrupted power supply protection for AC loads.

[0063] The DC terminal power distribution module 5 is used to separately combine the DC power of the second terminal power distribution circuit to the DC fast charging power distribution unit, and after internal hierarchical protection and power distribution, independently distribute it to multiple DC fast charging output interfaces for external output.

[0064] The core function of the DC terminal busbar distribution module is to efficiently and safely distribute the DC power from the second terminal distribution circuit to multiple DC fast charging output interfaces via the DC fast charging distribution unit, and maximize the utilization rate of fast charging power resources through real-time calculation of the total power limit and closed-loop dynamic redistribution algorithm.

[0065] After the powered device is connected to the DC fast charging output interface, the DC fast charging power distribution unit and the powered device complete a handshake process through the DC fast charging communication protocol (this embodiment supports the GB / T 27930 national standard communication protocol). After the handshake is completed, the DC fast charging power distribution unit obtains and continuously updates the charging request power of the powered devices connected to each interface in real time (denoted as the charging request power of each interface as...). , , The total number of currently active interfaces and the rated voltage of the powered platform are used as real-time inputs for subsequent power allocation calculations.

[0066] The DC fast charging power distribution unit continuously collects the real-time bus voltage of the DC 800V common DC main bus at a sampling frequency of not less than 100Hz. Real-time bus current , Provided by a high-precision DC voltage sensor installed at the DC800V common DC main bus junction. Power is supplied by a Hall effect current sensor installed on the main conductor of the DC 800V common DC main bus. Current power consumption of other loads in the system. The calculation is performed by multiplying the output current and output voltage of the first terminal power distribution circuit in real time, and this calculation is continuously executed at a sampling frequency of not less than 100Hz.

[0067] The DC fast charging power distribution unit calculates the current maximum total power available for allocation to the DC fast charging side in real time using the following formula. : ; in, The DC fast charging power ratio coefficient is the maximum proportion of the total available power of the DC 800V common DC main bus that can be allocated to the DC fast charging side. The introduction of this parameter enables the system to dynamically adjust the upper limit of power allocated to the DC fast charging side according to the operating mode and bus voltage status. It is the core parameter for achieving coordinated management of the power at the two ends of AC power supply and DC fast charging.

[0068] The dynamic adjustment follows three rules, arranged in descending order of priority: Rule 1: When the system is only operating the DC terminal combiner module (i.e., the AC terminal combiner module has no AC load connected or the inverter unit is not started), , Take the preset maximum value (This embodiment is calibrated) Approximately 5% power margin is reserved for bus voltage regulation and internal auxiliary power consumption. At this time... Maximize the available power resources on the DC fast charging side.

[0069] Rule 2: When the system is operating both the AC terminal combiner and the DC terminal combiner simultaneously... Still take the preset maximum value No numerical adjustment is made. At this time, By real-time monitoring of the product of the output current and output voltage of the first terminal power distribution circuit, this accurately reflects the total power consumption actually output by the AC terminal combiner module to the AC load; this consumption is... The power supply to the AC load is directly deducted as a subtraction term in the calculation formula, thus automatically ensuring that the power supply to the AC load is not compressed at the formula level. The remaining usable power after deduction is calculated accordingly. The full proportion is allocated to the DC fast charging side. The reason for not reducing the value is because The reduction function has fully achieved automatic coordination of the power at both ends, eliminating the need for further reduction. This provides an extra margin for AC power supply, avoiding the problem of excessive compression of available power on the DC fast charging side due to double reserves.

[0070] Rule 3: When the real-time voltage of the DC 800V common DC main bus... Below the preset low voltage threshold (This embodiment is calibrated) When the SOC of each energy storage unit drops to approximately 15% (a low state of charge), the DC fast charging distribution unit determines that the entire energy storage unit has entered the low-charge range and activates the low-voltage derating protection, following these steps: Implement linear reduction adjustment: Determine if it has entered the reduction range: If Higher than or equal to ,but Keep If unchanged, the reduced amount will not be activated; if Lower than or equal to the system's minimum allowable operating voltage (This embodiment is calibrated) ),but Maintain the lower limit value (This embodiment is calibrated) It will no longer decrease; exist to Perform linear interpolation between them: correspond Starting from, with correspond As the endpoint, For every 1V decrease, Decrease accordingly ;Right now Deviation The farther away, The smaller, The corresponding smooth reduction; The above linear interpolation result is used as the control cycle result. Take the value and substitute it. The calculation formula is applied to the current period.

[0071] The above linear depreciation steps ensure that The smooth reduction in the rate of bus voltage drop avoids... The sudden drop in fast charging output power caused by step changes can impact the charging process of the powered equipment, preventing excessive load on the DC fast charging side from causing a further drop in the real-time voltage of the bus and creating a positive feedback collapse risk.

[0072] DC fast charging power distribution unit To constrain the upper limit, dynamic power allocation is performed on the M active DC fast charging output interfaces according to the following steps: The first step is to determine if the total request power exceeds the limit: Summ up the charging request power of all currently active M interfaces to obtain the total request power; if the total request power does not exceed the limit... If the total requested power is exceeded, each interface will allocate the required power to its respective charging request, and no further steps are required. Then proceed to the second step.

[0073] The second step is to determine the SOC balancing condition: read the current SOC of each powered device and calculate the maximum difference in SOC between the devices. If the maximum difference is not less than the preset SOC balancing threshold (calibrated to 20% in this embodiment), then more power is allocated to the interface with the lowest SOC, and power is allocated to each interface in order of SOC from low to high until the threshold is reached. If the resource is exhausted, proceed to the third step to process the interfaces that have not received sufficient allocation. If the maximum difference is less than the SOC balancing threshold, then proceed to the handshake timing rule, that is, allocate resources to each interface in order of handshake completion time from earliest to latest, until... If the quota is exhausted, proceed to the third step to handle the interface that has not received sufficient allocation.

[0074] The third step is to perform a proportional reduction on interfaces that have not received sufficient allocation: All interfaces that have not yet received allocation after the above allocation steps are grouped into a set S, and the following calculations are performed. The remaining allocatable power after deducting the sum of the fully allocated power of each path (denoted as ) );by To determine the total allocated power, the power quota is calculated and allocated for each interface in set S according to its proportion of the total charging request power in set S. The allocated power for each interface is the same as its proportion of the total charging request power in set S, and the sum of all allocated quotas is exactly equal to the total power allocated to each interface in set S. The value should not exceed or fall below this value to ensure that each channel maintains a certain continuous charging output and to prevent any interface from being completely deprived of charging power.

[0075] In this embodiment, M=4 DC fast charging output interfaces, Taking a typical scenario as an example: the charging power requests of the four powered devices are 350kW, 300kW, 250kW, and 200kW respectively, with a total requested power of 1100kW exceeding [a certain threshold]. If the SOC difference is less than the balancing threshold, the power is allocated in full according to the handshake sequence: 350kW for the first path, 300kW for the second path, and the remaining... The third and fourth channels form a set S, which is reduced proportionally according to the charging power request ratio: the third channel's requested power accounts for 250 / 450 of the total requested power of set S, and is allocated approximately 83kW; the fourth channel accounts for 200 / 450, and is allocated approximately 67kW; the sum of the total allocated power of the four channels is exactly 800kW, the constraint is satisfied, and all four channels are in the charging output state.

[0076] After completing power distribution output, the DC fast charging power distribution unit does not execute statically all at once, but continuously monitors the system's operating status and immediately triggers re-execution when one of the following three conditions is met. Calculation and power allocation: Condition a: The difference between the actual output power of any interface and the corresponding allocated power exceeds a preset power deviation threshold (defined as 5% of the corresponding allocated power in this embodiment). This condition is set to address scenarios where the actual charging power received by the device is lower than its handshake request power (e.g., the device's BMS detects that the cell temperature is too high and actively limits the power). When the actual output power is lower than the allocated power, this difference represents unused reallocatable power resources. Triggering a redistribution can transfer these resources to other interfaces that require them, thereby improving the overall fast charging power utilization rate.

[0077] Condition b: Any interface triggers a protection action and is disconnected. This condition ensures that after a faulty interface exits the protection mode, its original allocated power quota is immediately recovered, and... After the update, the remaining active interfaces are re-allocated according to the allocation logic to optimize the allocation and eliminate the problem of idle and wasted power quotas of faulty interfaces under the fixed quota mode.

[0078] Condition c: The change exceeds the preset power fluctuation trigger threshold (calibrated in this embodiment as ). 3%, that is, the current The trigger threshold is approximately 24kW. This condition covers the continuous drop in bus voltage due to SOC changes. Continuously reduce AC load In typical scenarios such as significant fluctuations or a failure in a group of energy storage units leading to a decrease in the total output power of the bus, the system can proactively respond to system-level power resource changes. During reduction, promptly tighten the power distribution of each circuit to prevent the total output from exceeding the limit. When the power needs to be increased, the power distribution of each circuit should be expanded in a timely manner to make full use of the newly available power resources.

[0079] To prevent sudden changes in the output power of each interface after a redistribution trigger from disturbing the stability of the DC800V common DC main bus voltage, the output power of each interface is not switched to the new target allocation power in a step manner after each redistribution trigger. Instead, it is smoothly adjusted to the corresponding target allocation power in each control cycle according to the following steps: The first step is to calculate the maximum allowable adjustment amount for this cycle: based on the preset upper limit of the power adjustment slope. (In this embodiment, the speed is calibrated to be no more than 200 kW / s, meaning the time to climb from 0 to 1 MW is no less than 5 seconds) multiplied by the control cycle duration. This yields the maximum allowable power change for the current cycle.

[0080] The second step is to calculate the target deviation: subtract the current actual output power from the target allocated power to obtain the total deviation that still needs to be adjusted, and record its positive or negative direction (positive if the target is higher than the current, negative if the target is lower than the current).

[0081] The third step is to determine the actual adjustment amount for this period: take the smaller of the maximum allowable adjustment amount and the absolute value of the total deviation amount as the actual adjustment range for this period. The adjustment direction is consistent with the direction recorded in the second step, that is, when the target is higher than the current value, the power increases, and when the target is lower than the current value, the power decreases.

[0082] Fourth, repeat the above three steps until the actual output power converges to the target allocated power.

[0083] During the power smoothing adjustment process, the DC fast charging distribution unit continuously monitors the real-time voltage of the DC800V common DC main bus at a sampling frequency of no less than 100Hz. .when When the real-time value deviates from the nominal value of DC800V by more than the preset bus voltage stability threshold (calibrated to ±3% in this embodiment, i.e., an absolute value of approximately ±24V), the DC fast charging power distribution unit prioritizes suspending the power increase adjustment of all interfaces (the power decrease adjustment is not subject to this restriction, as power decrease is beneficial to reducing the bus load), in order to reduce the power extraction pressure on the bus from the DC fast charging side; After the voltage returns to the preset stable range of the bus voltage, the DC fast charging distribution unit continues to execute the unfinished power smoothing process from the power value before the pause, instead of recalculating from 0, thus avoiding excessive power ramp-up delay caused by repeated resets.

[0084] This power-priority pause mechanism and the DC fast charging power ratio coefficient in Rule 3 are related. The low-voltage linear derating mechanism together constitutes a dual-layer protection mechanism for stabilizing the DC 800V common DC main bus voltage. Low-voltage linear derating provides a trend-based preventative limit on the total power ceiling over a timescale of minutes to hours during natural SOC consumption, thus constituting slow protection. Power ramp-up pause, on the other hand, responds rapidly over a timescale of seconds when voltage disturbances occur, constituting fast protection. The two timescales complement each other, jointly ensuring the continuous stability of the DC 800V common DC main bus voltage during high-power output from multiple fast charging circuits.

[0085] The system also includes a human-machine collaborative intelligent operation and maintenance and adaptive scheduling module, which includes: The terminal multimodal perception unit is used to capture the three-dimensional physical movement trajectory data of maintenance personnel in real time and continuously through the sensor matrix built into the maintenance mobile terminal. The sensor matrix includes a six-axis gyroscope, a heart rate sensor and a three-dimensional displacement sensor. It also collects the multi-touch dwell time and fine interactive action sliding trajectory of maintenance personnel on the human-computer interaction GUI interface of the maintenance mobile terminal, thereby constructing a multi-dimensional dynamic behavior parameter vector set. The system mapping and intent cognition unit is used to collect the voltage fluctuation characteristics of the current DC800V common DC main bus through the pre-installed voltage sampling circuit, collect the state of charge of N energy storage units through the external battery management system, and collect the real-time power dispatch characteristic parameters of the bidirectional power conversion unit. Through the graph neural network digital twin model pre-installed on the local controller, the multi-dimensional dynamic behavior parameter vector set and the real-time power dispatch characteristic parameters are fused and extracted in a spatiotemporal manner. The system then calculates and generates an evolutionary feature vector that represents the current human-machine collaborative response state of the operation and maintenance personnel. The evolutionary feature vector includes the system anomaly optimization action index, the high-voltage environment operation pressure index, and the intervention urgency index. The adaptive strategy generation and decoupling unit is used to match and generate auxiliary intervention strategy parameters based on the comprehensive mapping of the intervention urgency index, system anomaly optimization action index and high-pressure environment operation pressure index in the evolution feature vector. The auxiliary intervention strategy parameters are decoupled into sub-units and decomposed into power limit commands for DC voltage regulation and shunt units and delay threshold update commands for dual power supply automatic switching units. At the same time, a spatiotemporal correlation trajectory mapping representation model for the decoupled commands is constructed based on the real-time operation topology of the system. The dynamic execution and fault-tolerant closed-loop unit is used to push auxiliary intervention strategy parameters to the maintenance mobile terminal in real time in the form of block streaming data packets divided according to time windows and dynamic guidance instructions in the human-machine interaction GUI floating window. This drives maintenance personnel to make collaborative decision-making responses in a closed loop. During the response execution process, the unit activates the technical constraint detection mechanism, extracts the preset maintenance target node by parsing the spatiotemporal correlation trajectory mapping representation model, and calculates the spatial deviation between the three-dimensional physical movement trajectory data of the maintenance mobile terminal and the preset maintenance target node in real time. When the spatial deviation exceeds the preset tolerance time threshold or a feedback interruption instruction is detected, the system automatically triggers the adaptive degradation control mechanism, terminates the current strategy matching flow, and locks the parameter modification permissions of the first and second end power distribution circuits, thereby completing the safe closed-loop feedback of human-machine collaborative interactive control.

[0086] In the prevailing understanding of existing technology, the safety of the aforementioned electrical system can be guaranteed simply by setting the operating thresholds for each circuit breaker and protective relay. However, in actual disaster relief or emergency power grid expansion and power supply tasks, environmental factors are extremely variable (high temperature, high humidity, drastic load changes), and operators are often in a state of "high stress." Once an alarm is triggered, due to the extremely high complexity of the system, the operator's actions can easily lead to secondary high-voltage accidents.

[0087] Based on the aforementioned deep-seated pain points in engineering sites, this invention constructs a complete closed-loop logic for human-machine collaborative intelligent operation and maintenance. This control logic runs within a local controller equipped with a high-performance edge computing chip, and works in conjunction with industrial-grade intelligent terminals on the personnel side.

[0088] The terminal multimodal sensing unit monitors the behavioral characteristics of maintenance personnel in real time at a sampling frequency of 100Hz, and simultaneously collects data in the following two modalities: The first mode is spatial positioning and motion characteristic data. Maintenance personnel wear smart bracelets or industrial helmets containing a six-axis inertial measurement unit (IMU) and UWB tags. The six-axis IMU consists of a three-axis accelerometer and a three-axis gyroscope, acquiring raw high-dynamic attitude and acceleration data of the personnel at a frequency of 500Hz. The UWB tags communicate in real-time with positioning anchor points at the four corners of the container's top wall using a two-way ranging protocol, obtaining flight time distance measurements from the tags to each anchor point, with a single ranging accuracy better than ±15 cm. The local controller incorporates an extended Kalman filter algorithm, fusing data using UWB ranging values ​​as observations and IMU integration results as predictions to eliminate zero-bias drift caused by long-term gyroscope integration. Finally, it outputs the three-dimensional absolute coordinates of the maintenance personnel in the container coordinate system, i.e., the three-dimensional physical movement trajectory data, at an update frequency of no less than 20Hz. Meanwhile, the system acquires pulse wave signals from the heart rate sensor and extracts the short-time frequency domain features of heart rate variability using the Lorenz scatter plot algorithm. Specifically, it extracts the ratio of low-frequency power to high-frequency power. This ratio serves as a characterization parameter for quantifying the degree of physiological stress in individuals. A higher ratio indicates a stronger degree of sympathetic nerve excitation and a more severe stress state.

[0089] The second modality is the operation trajectory data of the human-computer interaction GUI interface. The system records the landing point coordinate sequence of each touch event, the continuous dwell time (in milliseconds) of each control button, and the pixel-level trajectory coordinate stream of the sliding action through the touch driver layer of the mobile terminal being maintained. The touch dwell time reflects the degree of hesitation of the operator before executing the control action, and the number of backtracking steps and the deflection amplitude of the sliding trajectory reflect the stability of the operator's hand.

[0090] The above-mentioned three-dimensional absolute coordinate sequence, heart rate variability frequency domain ratio, touch dwell time vector, and sliding trajectory coordinate stream are normalized and then spliced ​​into a multi-dimensional dynamic behavior parameter vector set, which is then reported to the local controller in real time via Wi-Fi 6 LAN.

[0091] The system mapping and intent recognition unit within the local controller first reads the transient voltage sampling value of the DC800V main bus, the real-time output power of the bidirectional power conversion unit, and the bridge arm temperature via the CAN-FD bus. It then reads the state of charge and the highest temperature of each energy storage unit via the battery management system interface. These electrical and thermal parameters together constitute a set of real-time power dispatch characteristic parameters.

[0092] Subsequently, a graph neural network digital twin model pre-installed in the local controller memory is invoked. In this model, the physical power grid and the human-machine interface are jointly mapped to a graph structure according to the following rules: The set of nodes in the graph includes each group of energy storage units, bidirectional power conversion units, DC voltage regulation and shunt units, dual power supply automatic switching units, and each functional operation control on the human-machine interface. The initial static characteristics of each node are its rated electrical parameters (including rated voltage, rated power, and rated current); The set of edges in the graph includes two types of directed edges: one is the power edge, which connects two nodes with a direct power conduction relationship (such as a bus node and a converter node), and the initial weight of the edge is the rated current carrying capacity of the corresponding cable; the other is the control logic edge, which connects the GUI operation control node and its corresponding controlled equipment node, and the initial weight of the edge is the response priority coefficient of the instruction. During real-time operation, the local controller injects real-time power scheduling feature parameters into the dynamic feature domain of the corresponding device nodes and injects a multi-dimensional dynamic behavior parameter vector set into the dynamic feature domain of the GUI operation control nodes. Subsequently, the graph neural network iteratively calculates across the entire graph through a graph convolution message passing mechanism. After two to three layers of aggregation, it outputs a global graph embedding vector, which is then output through three independent fully connected regression heads. The values ​​of the three indicators are all normalized to between 0 and 1: The first indicator is the System Anomaly Optimization Action Index, which quantifies the degree to which operators are in a "confused exploration" state. This indicator is calculated by the corresponding regression head driven by the touch dwell time vector and the activation frequency sequence of the control logic edge. The higher the value, the more likely the operator is rapidly switching between multiple system status pages but has not issued any effective commands.

[0093] The second indicator is the high-pressure environment operation stress index, which is used to quantify the physiological stress level of operators. This indicator uses the ratio of low-frequency power to heart rate variability and the amplitude of high-frequency hand tremors (characterized by the root mean square value of the frequency components above 3Hz from the inertial measurement unit accelerometer) as the main input features, and is calculated by the corresponding regression head. The higher the value, the more physiologically stressed the personnel are.

[0094] The third indicator is the intervention urgency index, a core decision-making factor for comprehensively judging whether system intervention is necessary. This indicator is derived by weighted summation of three factors: the system abnormal optimization action index, the high-voltage environment operation pressure index, and the bus voltage over-limit margin. The formula for calculating the bus voltage over-limit margin is as follows: ; In the formula, The preset overvoltage protection setting (in volts) for the system. This is the current measured bus voltage value (in volts) acquired via the CAN-FD bus. The smaller the value, the closer the busbar is to the overvoltage limit, and the more dangerous the system. The complete formula for calculating the intervention urgency index is: ; In the formula, The intervention urgency index ranges from 0 to 1; The index for optimizing actions in response to system anomalies; This refers to the operating pressure index in a high-pressure environment. This refers to the over-limit margin of the bus voltage; , , These are the weighting coefficients corresponding to the three input items, and the sum of the three equals 1. The specific values ​​are determined by actual vehicle calibration when the system leaves the factory.

[0095] When either the intervention urgency index or the high-pressure environment operation pressure index exceeds the preset safety threshold (uniformly set to 0.75 in this preferred embodiment), the adaptive strategy generation and decoupling unit generates the corresponding degradation protection instruction parameter set and decouples it into two independent sub-instructions, which are then issued separately: First, the instruction is issued to the DC voltage regulation and shunt unit via the CAN-FD bus to reduce the upper limit of the converter current loop setpoint to 10% of the rated value to limit the system short-circuit capacity; Second, the instruction is written to the protection control register of the dual power supply automatic switching unit via the RS-485 bus to forcibly extend the switching trigger delay threshold from the default value of 10 milliseconds to 500 milliseconds, ensuring that the arc between the contacts has sufficient time to extinguish naturally when the operator accidentally touches the switching instruction.

[0096] Simultaneously, the system, combining the calibrated container three-dimensional coordinate system and the safety protection distance regulations for each high-voltage equipment (in this embodiment, the high-risk area for arcing is within 0.8 meters of the outer casing of each high-voltage equipment), calculates the nearest safe position point where maintenance personnel should retreat under the current operating conditions in the coordinate space, i.e., the preset maintenance target node. This node is ensured to be no less than 1.5 meters away from the outer casing of all high-voltage equipment, and the three-dimensional coordinates of this node are stored for subsequent steps. At the same time, the system renders a swipe gesture confirmation trajectory with mandatory completion constraints on the human-computer interaction GUI interface. This trajectory is a diagonal path from the lower left corner to the upper right corner of the interface, with three intermediate checkpoints that must be triggered sequentially. Each checkpoint requires a touch dwell time of no less than 500 milliseconds before further progress can be made.

[0097] The local controller splits the policy instruction parameter set into multiple subframes according to the intervention level. Each subframe contains a complete and independent operation guidance message. The message is pushed sequentially to the operation and maintenance mobile terminal via Wi-Fi 6 LAN at fixed time window intervals of no more than 200 milliseconds. The message is displayed one by one in the form of floating dynamic bubbles in the human-machine interaction GUI interface to avoid overloading of high-pressure emergency information.

[0098] Within the interval of each frame push, the system synchronously activates a technical constraint detection mechanism to calculate the straight-line distance between the current location of the maintenance personnel and the preset maintenance target node in real time, in order to determine whether the personnel have retreated to a safe area. The formula for calculating this straight-line distance is: ; In the formula, The Euclidean distance (in meters) between the current location of the maintenance personnel and the preset maintenance target node. , , These are the three-dimensional coordinate components (in meters) of the maintenance personnel in the container coordinate system, output in real time by the extended Kalman filter algorithm. , , These are the three-dimensional coordinate components (in meters) of the preset maintenance target node in the container coordinate system.

[0099] The system determines that the current human-machine collaborative execution exceeds the fault tolerance boundary when any of the following conditions are met: Condition 1 is the calculated distance. If the distance is still greater than the safe retreat distance threshold of 1.5 meters for more than 2000 milliseconds; the second condition is that the trajectory is interrupted during the GUI confirmation trajectory execution process, that is, the operator leaves after staying at any intermediate checkpoint for less than 500 milliseconds, or the touch point deviates from the center line of the preset trajectory path by more than 15% of the short side of the screen.

[0100] Once the above conditions are triggered, the local controller immediately broadcasts an emergency degradation frame via the CAN-FD bus, notifying all power conversion units to stop receiving parameter modification messages from the maintenance terminal. This means that the communication receive filters of each converter's control unit block write messages containing the maintenance terminal's IP address, retaining only read-only query permissions, thus locking the software-level parameter modification permissions for the first and second terminal power distribution circuits. Simultaneously, the local controller outputs a low-level blocking signal to the PWM enable pin of each power device's gate driver board via a dedicated hardwired digital output channel, forcibly preventing the driver board from sending any switching pulses to the power devices, putting the power circuits into a fully shut-off safety state. The response time of the hardwired digital output is no more than 1 millisecond, and its priority is higher than all software-level protocols, ensuring that the locking command can still be reliably executed when the software communication link is abnormal. At this point, the system completes a full human-machine collaborative closed-loop control from the identification of maintenance personnel's improper actions to the hardware-level safety shutdown.

[0101] Through this complete closed loop, the system combines the advantages of centralized high-voltage current collection of physical equipment with dual-track insurance functions for human perception recognition and rigid error prevention. This ensures that under most extreme working conditions, even if personnel movements are deformed or operations are improper, the system can perform hydraulic-level flexible control and cut-off protection in advance, thereby avoiding system collapse and personal safety risks.

[0102] This invention provides a mobile megawatt-level three-stage busbar distribution method based on a DC 800V primary DC bus, such as... Figure 2 As shown, it includes: Step 1: The external medium- and high-voltage AC power is bidirectionally converted by the bidirectional power conversion unit, and the converted DC 800V DC power is uniformly output to the DC 800V common DC main bus. Step 2: Connect all N energy storage units in the system to the DC 800V common DC main bus through their respective independent DC access circuits, so that the DC 800V common DC main bus becomes the only common junction node for DC power exchange between all energy storage units and bidirectional power conversion units in the system. Step 3: The DC power collected by the DC800V common DC main bus is regulated and current is shunted by the DC voltage regulation and shunting unit, and then output to the first and second terminal power distribution circuits which are electrically independent of each other. Step 4: Convert the DC power of the first terminal distribution circuit into AC power through the inverter unit, and then combine and manage it with the external AC backup power supply at the dual power supply automatic switching unit. Based on the availability of the external AC backup power supply, the priority power supply is automatically selected and output to the AC load in a unified manner. Step 5: The DC power from the second terminal power distribution circuit is separately fed into the DC fast charging power distribution unit, and after internal hierarchical protection and power distribution, it is independently distributed to multiple DC fast charging output interfaces for external output.

[0103] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A mobile megawatt three-level bus power distribution system based on a DC 800V primary DC bus, characterized in that, include: The first-level high-voltage combiner module is used to convert external medium- and high-voltage AC power through a bidirectional power conversion unit, and output the converted DC 800V DC power to the DC 800V common DC main bus. The secondary DC main bus module is used to connect all N energy storage units in the system to the DC800V common DC main bus through their respective independent DC access circuits, so that the DC800V common DC main bus becomes the only common bus node for DC power exchange between all energy storage units and bidirectional power conversion units in the system. The three-level terminal DC distribution module is used to stabilize the DC power collected by the DC800V common DC main bus and shunt the current through the DC voltage regulation and shunt unit, and output it to the first and second terminal power distribution circuits that are electrically independent of each other. The AC terminal power distribution module is used to convert the DC power of the first terminal power distribution circuit into AC power through the inverter unit, and to aggregate and manage it with the external AC backup power supply at the dual power supply automatic switching unit. It automatically selects the priority power supply according to the availability of the external AC backup power supply and outputs it to the AC load in a unified manner. The DC terminal power distribution module is used to separately combine the DC power of the second terminal power distribution circuit to the DC fast charging power distribution unit, and after internal hierarchical protection and power distribution, independently distribute it to multiple DC fast charging output interfaces for external output.

2. The mobile megawatt three-level bus power distribution system based on DC 800V primary DC bus according to claim 1, characterized in that, The primary high-voltage combiner module performs the following operations: External medium- and high-voltage AC power in the range of 6kV to 35kV is connected to the high-voltage input side of the bidirectional power conversion unit via the high-voltage incoming line protection unit; The bidirectional power conversion unit performs high-frequency isolation rectification on medium and high voltage AC power through built-in wide bandgap semiconductor power devices, converting medium and high voltage AC power into DC 800V DC power that matches the nominal total voltage level of the N groups of energy storage units in the system. The converted DC 800V DC power is output to the DC 800V common DC main bus. When the energy storage unit needs to feed energy back to the external power grid, the bidirectional power conversion unit is controlled to operate in reverse, converting the DC power on the DC 800V common DC main bus into medium- and high-voltage AC power and outputting it to the external power grid through the high-voltage incoming line protection unit.

3. The mobile megawatt three-level bus power distribution system based on DC 800V primary DC bus according to claim 1, characterized in that, The secondary DC main bus module performs the following operations: Each energy storage unit is equipped with an independent DC access circuit, and a pre-charge current limiting branch and a main circuit circuit breaker are connected in series in the DC access circuit. Before each energy storage unit is connected in parallel to the DC800V common DC main bus, the corresponding energy storage unit is first subjected to voltage equalization and current limiting processing through the pre-charge current limiting branch; the terminal voltage of the energy storage unit and the real-time voltage of the DC800V common DC main bus are collected by their respective voltage monitoring units. After the difference between the terminal voltage and the DC800V common DC main bus voltage is less than the preset voltage equalization threshold, the corresponding main circuit breaker is closed to complete the parallel connection and eliminate the parallel inrush current. After the parallel connection is completed, the current of each energy storage unit branch is continuously monitored by the current monitoring unit set in each DC access circuit. When the current of any branch exceeds the overcurrent protection action threshold of the corresponding branch, the corresponding main circuit circuit breaker is independently disconnected to achieve single-group fault isolation, and the remaining energy storage units and DC800V common DC main bus maintain normal operation.

4. The mobile megawatt three-level bus power distribution system based on DC 800V primary DC bus according to claim 1, characterized in that, The third-level terminal DC distribution module performs the following operations: The DC800V common DC main bus voltage is collected in real time. When the DC800V common DC main bus voltage fluctuates within the preset voltage fluctuation range due to the change in the state of charge of the energy storage unit, the DC voltage regulation and shunt unit adjusts the control parameters of the internal power devices to keep the output voltage of the first end distribution circuit and the second end distribution circuit stable within the preset deviation range of their respective rated values. The current direction monitoring unit of the corresponding circuit detects the current conduction direction in the first and second terminal power distribution circuits respectively. When the reverse conduction of current from the load side to the DC800V common DC main bus is detected in either terminal power distribution circuit, the electrical connection between the corresponding circuit and the DC800V common DC main bus is cut off to prevent the fault from spreading to the main bus level. When the system starts up or the end load is connected, soft start slope control is performed on the output current of the first end power distribution circuit and the second end power distribution circuit respectively, limiting the rise rate of the output current to within a preset value, and suppressing the disturbance of the power-on impact on the stability of the DC800V common DC main bus voltage.

5. The mobile megawatt three-level bus power distribution system based on DC 800V primary DC bus according to claim 1, characterized in that, The AC terminal busbar distribution module performs the following operations: The dual-power automatic switching unit continuously monitors the voltage amplitude, frequency, and phase sequence of the external AC backup power supply to determine whether the external AC backup power supply is in a qualified and usable state. When the external AC backup power supply is in a qualified and available state, the dual power automatic switching unit will switch the AC output of the inverter unit to the standby state and give priority to using the external AC backup power supply to supply power to the AC load. When the external AC backup power supply fails or its parameters exceed the acceptable range, the dual power supply automatic switching unit automatically switches to the AC output of the inverter unit within a preset switching time to continuously supply power to the AC load. The power interruption time during the switching process does not exceed the preset interruption time threshold.

6. The mobile megawatt three-level bus power distribution system based on DC 800V primary DC bus according to claim 1, characterized in that, The DC terminal busbar distribution module performs the following operations: The DC fast charging power distribution unit obtains the charging request power and rated voltage of the power receiving platform of the power receiving equipment connected to each DC fast charging output interface in real time through the DC fast charging communication protocol. The DC fast charging power distribution unit collects the real-time bus current and real-time bus voltage of the DC800V common DC main bus in real time, calculates and determines the current total power limit that the system can allocate to the DC fast charging side; based on the total power limit and the charging request power of the powered devices connected to each DC fast charging output interface, it dynamically calculates and allocates the output power of each DC fast charging output interface according to the power allocation strategy determined based on the relationship between the charging request power of each channel and the total power limit, so that the sum of the output power of each channel does not exceed the total power limit; Each DC fast charging output interface is independently deployed and continuously implemented with output overcurrent protection, short circuit protection, and insulation fault detection. When any interface triggers any protection action condition, the output of the corresponding interface is independently cut off. After the faulty interface is eliminated, the power distribution calculation is re-executed and the remaining interfaces continue to output normally.

7. The mobile megawatt three-level bus power distribution system based on DC 800V primary DC bus according to claim 3, characterized in that, The execution sequence of connecting each group of energy storage units in parallel to the DC 800V common DC main bus is determined as follows: Using the real-time voltage of the DC800V common DC main bus as a reference, the N groups of energy storage units are sorted in ascending order of the difference between their respective terminal voltage and the real-time voltage of the DC800V common DC main bus. The pre-charge equalization parallel connection of each group of energy storage units is performed in ascending order of the difference. Between the parallel connection operations of two adjacent groups, the pre-charge equalization parallel connection operation of the next group is performed only after the DC800V common DC main bus voltage has stabilized back to the preset voltage stability range.

8. The mobile megawatt three-level bus power distribution system based on DC 800V primary DC bus according to claim 6, characterized in that, The total power limit is calculated in real time using the following formula: ； Wherein, is the total power upper limit; is the real-time voltage of the DC 800V public DC main bus; is the real-time current of the bus; is the DC fast charging side power ratio coefficient; is the current consumption power of other loads of the system calculated by multiplying the output current and output voltage of the first end power distribution circuit detected in real time. Wherein, the direct current fast charging side power ratio coefficient Adjust dynamically according to the following rules: When the system only runs the DC end bus power distribution module, Take the preset maximum value; When the system operates both the AC terminal combiner and the DC terminal combiner, priority is given to ensuring the power supply requirements of the AC load in the AC terminal combiner, and the remaining power after ensuring the AC load is fully allocated to the DC fast charging side. When the real-time voltage of the DC800V common DC main bus is lower than the preset low-voltage threshold... As the real-time bus voltage decreases, it decreases linearly according to the preset derating curve, so that the total power limit is reduced smoothly, preventing the real-time bus voltage from dropping further due to excessive load on the DC fast charging side.

9. A mobile megawatt-level three-stage busbar distribution system based on a DC 800V primary DC busbar as described in claim 8, characterized in that, Each time the power allocation is re-executed, the output power of each DC fast charging output interface is smoothly adjusted to the corresponding target allocation power at a rate not exceeding the preset power adjustment slope. When the real-time voltage deviation of the DC800V common DC main bus exceeds the preset bus voltage stability threshold during the adjustment process, the power increase adjustment of all interfaces is suspended first. After the real-time voltage of the DC800V common DC main bus recovers to the preset bus voltage stability range, the unfinished power increase adjustment is continued.

10. A mobile megawatt-level three-stage busbar distribution method based on a DC 800V primary DC bus, characterized in that, include: Step 1: The external medium- and high-voltage AC power is bidirectionally converted by the bidirectional power conversion unit, and the converted DC 800V DC power is uniformly output to the DC 800V common DC main bus. Step 2: Connect all N energy storage units in the system to the DC 800V common DC main bus through their respective independent DC access circuits, so that the DC 800V common DC main bus becomes the only common junction node for DC power exchange between all energy storage units and bidirectional power conversion units in the system. Step 3: The DC power collected by the DC800V common DC main bus is regulated and current is shunted by the DC voltage regulation and shunting unit, and then output to the first and second terminal power distribution circuits which are electrically independent of each other. Step 4: Convert the DC power of the first terminal distribution circuit into AC power through the inverter unit, and then combine and manage it with the external AC backup power supply at the dual power supply automatic switching unit. Based on the availability of the external AC backup power supply, the priority power supply is automatically selected and output to the AC load in a unified manner. Step 5: The DC power from the second terminal power distribution circuit is separately fed into the DC fast charging power distribution unit, and after internal hierarchical protection and power distribution, it is independently distributed to multiple DC fast charging output interfaces for external output.

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