Micro-grid bus voltage control method and system based on group string DCDC energy conversion

Abstract

The application relates to the technical field of power energy storage management, and discloses a microgrid bus voltage control method and system based on group string type DCDC energy conversion. The method comprises the following steps: calculating a bus voltage deviation; adopting a layered decoupling weight adjustment mechanism to perform constant voltage control; performing bus power balance determination; adopting a limiting amplitude proportional adjustment mechanism to generate a battery power reference value; and adopting a power collaborative adjustment mechanism to perform power distribution. Compared with the traditional adjustment strategy in the prior art which only relies on bus voltage deviation single-point feedback and cannot fully link the batteries, the power grid and the load side equipment, especially under the condition of simultaneous access or on-off grid dynamic switching, the technical problem that the bus cannot be quickly and stably regulated is solved. Since the application constructs a pressure difference driven coupling judgment mechanism, combines the limiting amplitude proportional adjustment and the on-off grid dynamic distribution strategy, the problem of excessive bus voltage fluctuation caused by single-point feedback adjustment failure is avoided, and the bus stable regulation and control capability is improved.

Description

Technical Field

[0001] This invention relates to the field of power energy storage management technology, and in particular to a microgrid bus voltage control method and system based on string DC-DC energy conversion. Background Technology

[0002] Currently, with the large-scale deployment of new energy storage systems, especially against the backdrop of the increasing popularity of photovoltaic-storage DC bus architecture, how to achieve stable bus voltage control in a multi-channel DC-DC parallel structure has become a key issue in system stability design. Most mainstream control methods currently employ centralized coordination strategies or independent branch voltage control methods, but in complex operating scenarios, they still have the following shortcomings: First, in string DC-DC topologies, the input sources (such as photovoltaic arrays) and output loads (such as DC buses, charging piles, and battery systems) of each branch DC-DC module have inconsistent voltage levels. This is common in designs with constant voltage output at end A, floating power supply at end B, or bidirectional DC-DC mutual coupling operation. This leads to voltage deviations and power backflow issues between modules, and traditional constant voltage or constant current control methods cannot simultaneously ensure coupling stability and inter-module coordinated response speed. Second, in practical engineering, energy storage systems need to frequently switch between grid-connected operation and off-grid islanded operation, and most current control logics fail to adapt to these system modes. For example, in grid-connected mode, fluctuations in the DC bus should be actively absorbed or released by the DCAC module to absorb or release redundant energy; while in off-grid mode, the system relies on the dynamic coordination of the batteries and photovoltaics to maintain the bus voltage. However, in existing methods, there is a lack of linkage mechanism between DCAC power control and the DC-DC module, making it difficult to quickly converge control errors, leading to severe fluctuations in bus voltage or system instability.

[0003] Therefore, there is an urgent need for a microgrid bus voltage control method based on string DC-DC energy conversion, in order to achieve higher precision bus voltage stability control and energy coordinated scheduling under complex operating conditions and multi-source dynamic environments, thereby improving the reliability, response speed and power coordination capability of the energy storage system. Summary of the Invention

[0004] To address the aforementioned technical shortcomings, the purpose of this invention is to propose a microgrid bus voltage control method based on string DC-DC power conversion. This method aims to solve the technical problem of traditional regulation strategies that rely solely on single-point feedback of bus voltage deviation and cannot fully link batteries, the power grid, and load-side equipment, especially under conditions of simultaneous connection or dynamic switching between grid and off-grid, where the bus voltage cannot be quickly and stably controlled.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention provides a microgrid bus voltage control method based on string DC-DC power conversion.

[0006] The microgrid bus voltage control method based on string DC-DC power conversion includes:

[0007] Step S10: Acquire the voltage at terminal A of the i-th DC-DC module in the string DC-DC system at time t. B-terminal voltage And based on the DC bus given value The busbar voltage deviation is calculated according to the nominal value. ;

[0008] Step S20: Based on busbar voltage deviation A weighted adjustment mechanism based on hierarchical decoupling is used to adjust the voltage at terminal A. B-terminal voltage Perform constant voltage control and output constant voltage control voltage at terminal A. and constant voltage control at terminal B ;

[0009] Step S30: Based on the constant voltage control voltage at terminal A and constant voltage control at terminal B A pressure-differential driven coupled analysis mechanism is used to perform the busbar power balance determination task and output a unified energy balance command. ;

[0010] Step S40: Based on the unified energy balance command The battery power reference value generation task is performed using a limiting proportional adjustment mechanism, and the battery reference power is output. ;

[0011] Step S50: Based on battery reference power A power coordinated regulation mechanism based on grid-connected and off-grid modes is adopted to perform the busbar voltage stabilization control task and output the busbar voltage regulation result set.

[0012] Preferably, in step S10, ,in This represents the real-time voltage of the DC bus in a string DC-DC system at time t.

[0013] Preferably, in step S20, based on the busbar voltage deviation A weighted adjustment mechanism based on hierarchical decoupling is used to adjust the voltage at terminal A. B-terminal voltage Perform constant voltage control and output constant voltage control voltage at terminal A. and constant voltage control at terminal B The steps specifically include:

[0014] Step S201: First, based on the busbar voltage deviation For the voltage at terminal A Constant voltage control is achieved using proportional-integral (PI) control, outputting a constant voltage control voltage at terminal A. ;

[0015] Step S202: Then, regarding the voltage at terminal B... Get the B-end connection status of the i-th DC-DC module at time t;

[0016] Step S203: When the connection status of terminal B is "photovoltaic connection", obtain the open-circuit voltage of the photovoltaic subarray. With real-time photovoltaic power And based on the open-circuit voltage of the photovoltaic subarray With real-time photovoltaic power The MPPT tracking task is executed to generate the photovoltaic operating voltage, which is then used as the constant voltage control voltage at terminal B. Output;

[0017] Step S204: When the connection status of terminal B is "battery connected", obtain the battery state of charge (SOC(t)) and calculate it based on the busbar voltage deviation. The battery's state of charge (SOC(t)) is dynamically adjusted using a weighted flexible regulation mechanism based on SOC partitioning to generate the battery-side operating voltage. The battery-side operating voltage is used as the constant voltage control voltage at terminal B. Output.

[0018] Preferably, in step S20, the battery-side operating voltage The formula is expressed as:

[0019] ;

[0020] in, This is the proportional adjustment coefficient; Battery response weighting factor;

[0021] Battery response weighting factor The battery state of charge (SOC(t)) is partitioned as follows:

[0022] ;

[0023] when When, it indicates that the battery's state of charge (SOC(t)) has entered the over-sufficient region; when When the battery's state of charge (SOC(t)) enters the optimal adjustment range, it indicates that the battery's SOC(t) has reached the optimal adjustment range. When the battery's state of charge (SOC(t)) enters the critical under-discharge zone, it indicates that the battery's SOC(t) has entered the critical under-discharge zone.

[0024] Preferably, in step S30, the constant voltage control voltage at terminal A is used. and constant voltage control at terminal B A pressure-differential driven coupled analysis mechanism is used to perform the busbar power balance determination task and output a unified energy balance command. The steps specifically include:

[0025] Step S301: Based on the constant voltage control voltage at terminal A and constant voltage control at terminal B The average pressure difference was calculated. , Where N is the number of DC-DC modules currently running in the string DC-DC system;

[0026] Step S302: When the busbar voltage deviation and When the busbar power is excessive, it is determined that the string DC-DC system is in a state of excess power; the state of excess power means that the busbar needs to absorb power.

[0027] When the busbar voltage deviation and When the busbar power is insufficient, it is determined that the string DC-DC system is in a state of insufficient busbar power; the state of insufficient busbar power means that the busbar needs to release power.

[0028] Step S303: Output a unified energy balance command based on the different states of the string DC-DC system. .

[0029] Preferably, in step S40, based on the unified energy balance command... The battery power reference value generation task is performed using a limiting proportional adjustment mechanism, and the battery reference power is output. The steps specifically include:

[0030] Step S401: When At that time, the upper limit limiting function is used to perform the battery power reference value generation task, and the battery reference power is output. ; ,in, This is an upper limit limiting function; This is the energy absorption adjustment ratio coefficient; This represents the current maximum charging power limit of the battery.

[0031] Step S402: When At that time, the lower limit limiting function is used to perform the battery power reference value generation task, and the battery reference power is output. ; ,in, This is the lower limit of the battery's current maximum discharge power. This is the proportional coefficient for adjusting the energy release.

[0032] Preferably, in step S50, based on the battery reference power The steps for implementing busbar voltage stabilization control using a power coordinated regulation mechanism based on grid-connected and off-grid modes, and outputting a set of busbar voltage regulation results, specifically include:

[0033] Step S501: Obtain the current system operating mode parameters, which include grid-connected operation mode and off-grid operation mode;

[0034] Step S502: When in grid-connected operation mode:

[0035] If the busbar voltage deviation And when the battery state of charge (SOC(t)) is greater than the preset battery state of charge threshold, then based on the battery reference power... Instruct the DCAC module to feed power to the grid;

[0036] If the busbar voltage deviation Based on the battery reference power The DCAC module is instructed to draw energy from the power grid;

[0037] Step S503: When in off-grid mode: Obtain real-time photovoltaic power. The DCAC module is based on the battery reference power. With real-time photovoltaic power The power supply of the charging pile is dynamically adjusted based on the priority of remaining power supply capacity;

[0038] Step S504: Output bus voltage regulation result set, which includes grid interaction power, charging pile target power, real-time regulation residual index and bus regulation status identifier.

[0039] The present invention also provides a microgrid bus voltage control system based on string DC-DC power conversion, comprising:

[0040] The busbar voltage deviation acquisition module is used to acquire the voltage at terminal A of the i-th DC-DC module in a string DC-DC system at time t. B-terminal voltage The busbar voltage deviation is calculated based on the nominal value of the DC bus given value. ;

[0041] A layered weighted constant voltage regulation module is used to regulate voltage based on busbar voltage deviation. A weighted adjustment mechanism based on hierarchical decoupling is used to adjust the voltage at terminal A. B-terminal voltage Perform constant voltage control and output constant voltage control voltage at terminal A. and constant voltage control at terminal B ;

[0042] The differential voltage coupling power determination module is used to control the voltage based on the constant voltage at terminal A. and constant voltage control at terminal B A pressure-differential driven coupled analysis mechanism is used to perform the busbar power balance determination task and output a unified energy balance command. ;

[0043] Limiting proportional power generation module, used for unified energy balance command The battery power reference value generation task is performed using a limiting proportional adjustment mechanism, and the battery reference power is output. ;

[0044] On-grid and off-grid coordinated voltage regulation module, used for battery reference power A power coordinated regulation mechanism based on grid-connected and off-grid modes is adopted to perform the busbar voltage stabilization control task and output the busbar voltage regulation result set.

[0045] The present invention also provides a microgrid bus voltage control device based on string DC-DC power conversion, comprising: a memory, a processor, and a microgrid bus voltage control program based on string DC-DC power conversion stored in the memory and executable on the processor. When the microgrid bus voltage control program based on string DC-DC power conversion is executed by the processor, a microgrid bus voltage control method based on string DC-DC power conversion is implemented.

[0046] The present invention also provides a computer program product, including a microgrid bus voltage control program based on string DC-DC power conversion, wherein the microgrid bus voltage control program based on string DC-DC power conversion, when executed by a processor, implements the microgrid bus voltage control method based on string DC-DC power conversion.

[0047] The beneficial effects of this invention are as follows: This invention, through the coupling judgment mechanism of voltage control and differential voltage drive with hierarchical decoupling, can flexibly perform constant voltage adjustment according to the voltage deviation between terminals A and B. At the same time, it dynamically generates battery reference power in combination with unified energy balance command, thereby achieving fast-response voltage stability control under conditions of multi-terminal coupling of string DC-DC modules, drastic load changes or frequent grid fluctuations, and significantly improving the system's ability to suppress fluctuation disturbances.

[0048] This invention constructs a power collaborative regulation mechanism based on system operation mode recognition. In grid-connected mode, it can automatically control the bidirectional flow of DC-AC power according to the battery state of charge and bus voltage deviation. In off-grid mode, it integrates photovoltaic power for dynamic power allocation, thereby ensuring the voltage continuity and energy supply security of the system during state switching processes such as grid faults and islanded operation, and enhancing the flexible scheduling capability and engineering adaptability of the energy storage system in real-world scenarios. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a flowchart illustrating the first embodiment of a microgrid bus voltage control method based on string DC-DC power conversion according to the present invention.

[0051] Figure 2 This is a schematic diagram of the overall control structure of a string DC-DC energy conversion system, which is the first embodiment of a microgrid bus voltage control method based on string DC-DC energy conversion according to the present invention.

[0052] Figure 3 This is a schematic diagram of a microgrid bus voltage control method based on string DC-DC power conversion according to the present invention. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Example 1: As Figure 1 The diagram shown is a flowchart of the first embodiment of the microgrid bus voltage control method based on string DC-DC energy conversion of the present invention, which presents the first embodiment of the microgrid bus voltage control method based on string DC-DC energy conversion of the present invention.

[0055] In the first embodiment, the microgrid bus voltage control method based on string DC-DC power conversion includes:

[0056] Step S10: Acquire the voltage at terminal A of the i-th DC-DC module in the string DC-DC system at time t. B-terminal voltage And based on the DC bus given value The busbar voltage deviation is calculated according to the nominal value. ;

[0057] It should be noted that "busbar voltage deviation" refers to the difference between the weighted average of the voltage at terminal A and terminal B collected by the i-th DC-DC module at time t and the preset nominal DC busbar voltage. This difference not only reflects the current output voltage state of the module itself, but also measures the instantaneous deviation of the overall busbar voltage relative to the reference value.

[0058] It should be noted that the DC bus setpoint The setpoint voltage for the DC bus is determined by the output voltage of all string DC-DC converters and the peak-to-peak value of the mains voltage under grid-connected conditions. For example, when one end of the DC-DC converter is a photovoltaic system, the DC bus setpoint is generally selected as the photovoltaic MPPT point voltage plus a margin voltage. The DC-DC converter here also needs to have a buck-boost architecture that allows energy to flow unidirectionally to the bus after buck-boost conversion. When one end of the DC-DC converter is a battery system, the DC bus setpoint is generally selected as the current total battery voltage plus a margin voltage ΔU. The DC-DC converter here needs to have the ability to flow bidirectionally (bidirectional boost). When one end of the DC-DC converter is an electric vehicle power battery, the DC bus setpoint is generally selected as the current total power battery voltage plus a margin voltage ΔU. The DC-DC converter here needs to have the ability to charge the battery unidirectionally (buck) or the ability to flow bidirectionally from VtoG (bidirectional boost). At the same time, the DC bus setpoint must be greater than the peak-to-peak value of the mains voltage plus the margin voltage ΔU to ensure that the bus will not be unstable due to backflow of energy from the mains when it enters grid-connected mode.

[0059] Understandably, by acquiring the voltages at terminals A and B in real time during each sampling period and calculating the deviation from the nominal value given by the DC bus, this step provides a more accurate basis for judging the busbar status. Compared to single-ended sampling, which only reflects local branch information, this step utilizes dual-ended information to effectively characterize the overall electrical environment of the busbar, thereby significantly improving the response speed, judgment accuracy, and dynamic adaptability of subsequent constant voltage regulation, power judgment, and coordinated control. Ultimately, this helps maintain the stability of the busbar voltage in rapidly changing scenarios such as battery charging and discharging switching, photovoltaic output fluctuations, and sudden changes in charging pile power.

[0060] Step S20: Based on busbar voltage deviation A weighted adjustment mechanism based on hierarchical decoupling is used to adjust the voltage at terminal A. B-terminal voltage Perform constant voltage control and output constant voltage control voltage at terminal A. and constant voltage control at terminal B ;

[0061] It should be noted that the "layered decoupling weight adjustment mechanism" refers to the process of layering the bus voltage deviation according to its impact on different ports during constant voltage control, and setting independent weight adjustment factors for ports A and B respectively, thereby achieving decoupling of voltage control between the output side and the feedback side. Specifically, this mechanism includes: deviation layering (e.g., dividing into static deviation layer and dynamic deviation layer), port weight allocation (setting adjustable weight coefficients for ports A and B respectively), and independent voltage correction stage (applying different adjustment amplitudes according to different port characteristics). Through the above structured adjustment, accurate dynamic constant voltage control of the port voltage can be achieved under different load conditions and different output source characteristics.

[0062] Understandably, through a weighted adjustment mechanism based on deviation hierarchy, this step decomposes the busbar deviation signal in the control path. The A-end control loop promptly handles rapid disturbances, while the B-end control loop handles slow voltage drift or load changes, thus improving the consistency and dynamic response of the voltage regulation targets at both ports. This mechanism not only maintains the steady-state voltage stability of the DCDC module on the output side (A-end) but also effectively suppresses the floating voltage at the B-end caused by load coupling, thereby providing a stable and reliable port voltage foundation for subsequent power balance determination.

[0063] It should be understood that, compared to the traditional approach using only a single PI constant voltage controller, this step significantly improves control robustness under conditions of multiple modules in parallel, sudden load changes, and strong port coupling by introducing a multi-path constant voltage strategy with hierarchical decoupling and weight adjustment. Traditional solutions often suffer from voltage regulation at terminal A causing oscillation at terminal B, or correction at terminal B causing voltage deviation at terminal A. However, this invention, through adaptive allocation of weight parameters and weak coupling design between port control loops, can maintain a stable and consistent voltage control effect under different port characteristics and different busbar operating conditions, reducing mutual interference and improving voltage regulation accuracy.

[0064] For example, in a real-world operating scenario, a DC-DC module experienced a sudden increase in system load (from 18kW to 40kW), causing its B-terminal voltage to drop by approximately 6V, while the A-terminal voltage also fluctuated by about 3V. Using a traditional PI control strategy, the controller's adjustment of the two ports exhibits a coupling effect, leading to a continuous amplification of the voltage deviations at both terminals A and B within 150ms, resulting in significant busbar voltage fluctuations. However, by employing the hierarchical decoupling weighted adjustment mechanism described in this step, the busbar deviation signal is responded to by the fast channel at terminal A in the first layer and smoothly corrected by the slow channel at terminal B in the second layer. This allows the voltages at terminals A and B to recover to 749.2V and 750.8V respectively within approximately 40ms, reducing the fluctuation amplitude by about 70% and shortening the voltage recovery time to one-quarter of the original scheme. Experimental results demonstrate that the constant voltage control after hierarchical decoupling exhibits significant resistance to sudden load changes.

[0065] Step S30: Based on the constant voltage control voltage at terminal A and constant voltage control at terminal B A pressure-differential driven coupled analysis mechanism is used to perform the busbar power balance determination task and output a unified energy balance command. ;

[0066] It should be noted that the "differential voltage driven coupling analysis mechanism" refers to extracting the voltage response differences during actual operation based on the voltage control results of each module's output port in a string DC-DC system. The constant voltage control results at terminals A and B of each module are compared one by one to form a set of voltage differences over a certain period. Subsequently, aggregation and coupling analysis are performed based on these differential voltage values ​​to determine whether there is a severe imbalance between power supply and absorption on the busbar side. This mechanism does not rely on voltage or current data at a single point, but rather starts from the relative states between multiple modules to comprehensively form the basis for judging the busbar's energy state, and ultimately outputs a unified energy balance command to guide the coordinated adjustment of each module.

[0067] Understandably, this invention enables real-time and accurate identification of busbar power status at the module level. Compared to traditional solutions that rely solely on busbar voltage levels, this invention utilizes the synergistic differences in voltage responses between modules as an analytical dimension, resulting in higher sensitivity and stability. In cases of slight power imbalance, this mechanism can quickly identify abnormal trends; in cases of significant power disturbances, it ensures that busbar voltage fluctuations are not amplified. Simultaneously, the unified energy balance command generation method guarantees consistency in multi-module control responses, avoiding issues such as "multi-module misadjustment" or "module contention for control."

[0068] For example, in a photovoltaic-storage-charging integrated site with multiple bidirectional DC-DC modules, when the photovoltaic power rises rapidly at midday, causing the busbar voltage to spike in a short period, relying solely on the traditional busbar voltage threshold triggering method may lead to response delays, or even some modules absorbing energy in reverse. Using the mechanism described in this invention, the rapid rise in the voltage at the A-end of most modules, while the voltage at the B-end does not rise synchronously, forms a significant voltage difference concentration state. This is immediately identified as a "power excess" state, and a unified power suppression command is generated, controlling some modules to switch to a low-power output state or shutting down some current paths, ultimately achieving rapid stabilization of the busbar voltage. Test data shows that compared to the traditional voltage closed-loop control scheme, this solution reduces the adjustment delay by about one-third and narrows the busbar voltage stability range by nearly half, effectively improving the adaptive stabilization capability under rapid power fluctuation scenarios.

[0069] Step S40: Based on the unified energy balance command The battery power reference value generation task is performed using a limiting proportional adjustment mechanism, and the battery reference power is output. ;

[0070] It should be noted that the "limiting ratio adjustment mechanism" refers to the process of generating a battery power reference value. Based on the power state (i.e., the power to be absorbed or released) indicated by the unified energy balance command output in the previous steps, a proportional adjustment factor is used to allocate the target power to the current battery module. Simultaneously, to prevent risks such as overcurrent or undercurrent during battery charging and discharging due to excessively high or low reference power commands, an adjustable limiting range is preset to dynamically limit and correct the reference power. The upper and lower limits of the limiting can be adjusted in real time based on the current battery pack's status information (such as temperature, voltage, and state of charge), ensuring that the generated reference power command always fluctuates within a safe operating range.

[0071] Understandably, this design step balances dynamic response speed and safety control boundaries when performing battery power regulation, achieving flexible and robust power following capability. This mechanism avoids the abrupt changes caused by "naked tracking" of the unified energy balance command, while also enhancing the battery pack's health protection capabilities during long-term operation. When the target power changes drastically, the limiting proportional adjustment mechanism effectively absorbs the impact of these changes, outputting a smooth reference power curve, thereby reducing the dynamic stress on the battery charging and discharging circuit and improving control stability and response coordination.

[0072] For example, such as Figure 2 As shown, in the microgrid bus voltage control system structure based on string DC-DC power conversion, after the control module detects that the busbar is in a state of excess power, it initiates the battery power regulation process according to the unified energy balance command. At this time, the controller first senses the voltage, current, and temperature status of the current battery cluster and dynamically limits the reference power command to be issued. Through the limiting ratio adjustment mechanism, a set of smooth and safe battery reference power commands is output and transmitted to the corresponding DC-DC modules to achieve individual power coordination control. As can be seen in the figure, multiple DC-DC modules are connected to a unified busbar. When the busbar is in a state of absorbing power demand, the DC-DC modules do not respond to maximum power charging at the same time, but generate differentiated and limited reference power according to the battery status. For example, if the battery management module on the right side of the figure provides real-time feedback that the current temperature is too high, it will reduce the reference power output of its corresponding DC-DC module to avoid the risk of overheating, and ultimately achieve the dual goals of energy balance regulation and health protection at the individual battery level.

[0073] Step S50: Based on battery reference power A power coordinated regulation mechanism based on grid-connected and off-grid modes is adopted to perform the busbar voltage stabilization control task and output the busbar voltage regulation result set.

[0074] It should be noted that the "power coordinated regulation mechanism based on grid-connected and off-grid modes" refers to the following: In this step, differentiated busbar voltage regulation strategies are adopted according to the current operating mode (whether in grid-connected or off-grid mode). In grid-connected mode, the charging and discharging power of the battery pack and the grid-connected converter's ability to regulate the busbar voltage are coordinated to achieve rapid suppression of voltage disturbances. In off-grid mode, the battery module undertakes the main voltage maintenance task, using real-time feedback control based on the deviation between the power reference value and the current load power to dynamically adjust the DC-DC output to support busbar stability. In addition, this mechanism also considers load balancing between strings, fluctuation suppression, and dynamic response constraints during grid-connected / off-grid switching to ensure that the busbar voltage does not deviate beyond limits due to switching impacts.

[0075] Understandably, this design integrates control strategies under different operating modes into the power coordination regulation logic, enabling the controller to quickly switch regulation strategies and seamlessly connect them when the state changes. Compared to traditional fixed regulation strategies, this solution can intelligently allocate voltage regulation tasks according to the actual operating state, improving the regulation accuracy of bus voltage control. It is particularly suitable for the dynamic fluctuation suppression and rapid response requirements in multi-source access scenarios of photovoltaic-storage DC buses.

[0076] It should be understood that, compared to traditional methods that rely solely on a single module to regulate bus voltage (such as relying solely on a grid-connected inverter or energy storage system), the power coordination regulation mechanism of this invention, while ensuring safety boundaries, integrates the controllable capabilities of multiple sources—energy storage, power supply, and load side—to achieve dynamic power sharing and feedback regulation among multiple sources under different operating modes. This mechanism can reduce the dependence of the bus voltage control system on any single module; especially in off-grid mode, when the grid-connected converter disconnects from the grid and exits control, it can still achieve independent and stable operation by relying on closed-loop regulation of the battery-side reference power.

[0077] For example, when operating in off-grid mode and load fluctuations cause a drop in bus voltage, the controller, based on the battery reference power command generated in step S40, instructs the DC-DC module to appropriately increase its output power to compensate for the power shortfall on the load side, thereby raising the bus voltage to the target value. Conversely, when in grid-connected mode and a surge in photovoltaic output causes a rise in bus voltage, the controller can simultaneously utilize the battery's absorption capacity and the grid-connected converter's reactive power regulation capacity to collaboratively absorb excess energy and suppress voltage overshoot. Through this mechanism, stable and continuous bus voltage regulation can be achieved regardless of whether the system is in grid-connected, off-grid, or transitional state, ensuring the stability of load power supply and the safe operation of critical equipment.

[0078] Example 2: Furthermore, the present invention provides a microgrid bus voltage control system based on string DC-DC power conversion, employing a microgrid bus voltage control method based on string DC-DC power conversion as described in the above embodiments, which can solve the technical problem of microgrid bus voltage control based on string DC-DC power conversion. Compared with the prior art, the beneficial effects of the microgrid bus voltage control system based on string DC-DC power conversion provided by the present invention are the same as those of the microgrid bus voltage control method based on string DC-DC power conversion provided in the above embodiments, and other technical features in the microgrid bus voltage control system based on string DC-DC power conversion are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0079] Example 3: This invention provides a microgrid bus voltage control device based on string DC-DC power conversion. Please refer to... Figure 3A microgrid bus voltage control device based on string DC-DC power conversion includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, which are executed by the at least one processor to enable the at least one processor to execute the microgrid bus voltage control method based on string DC-DC power conversion described in Embodiment 1 above. The microgrid bus voltage control device based on string DC-DC power conversion in this embodiment of the invention may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and in-vehicle terminals (e.g., in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers. This microgrid bus voltage control device based on string DC-DC power conversion is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of the invention. A microgrid bus voltage control device based on string DC-DC power conversion may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory 1002 or a program loaded from a storage device 1003 into a random access memory 1004. The random access memory 1004 also stores various programs and data required for the operation of the microgrid bus voltage control device based on string DC-DC power conversion. The processing unit 1001, the read-only memory 1002, and the random access memory 1004 are interconnected via a bus 1005. An I / O interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows a microgrid bus voltage control device based on string DC-DC power conversion to communicate wirelessly or wiredly with other devices to exchange data. Although a microgrid bus voltage control device based on string DC-DC power conversion with various systems is shown in the figure, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems may be implemented alternatively.

[0080] Example 4: This invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the microgrid bus voltage control method based on string DC-DC power conversion as described above. The computer program product provided by this invention can solve the technical problem of microgrid bus voltage control based on string DC-DC power conversion. Compared with the prior art, the beneficial effects of the computer program product provided by this invention are the same as those of the microgrid bus voltage control method based on string DC-DC power conversion provided in the above embodiments, and will not be repeated here.

[0081] In particular, according to the embodiments disclosed in this invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from read-only memory 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this invention.

[0082] It should be understood that the various parts disclosed in this invention can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0083] 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 microgrid bus voltage control method based on string DC-DC power conversion, characterized in that, The methods include: Step S10: Acquire the voltage at terminal A of the i-th DC-DC module in the string DC-DC system at time t. B-terminal voltage And based on the DC bus given value The busbar voltage deviation is calculated according to the nominal value. ; Step S20: Based on busbar voltage deviation A weighted adjustment mechanism based on hierarchical decoupling is used to adjust the voltage at terminal A. B-terminal voltage Perform constant voltage control and output constant voltage control voltage at terminal A. and constant voltage control at terminal B Specifically, this includes: Firstly, based on the busbar voltage deviation For the voltage at terminal A Constant voltage control is achieved using proportional-integral (PI) control, outputting a constant voltage control voltage at terminal A. ; Regarding the voltage at terminal B... Get the B-end connection status of the i-th DC-DC module at time t; When the connection status of terminal B is "PV Connection", obtain the open-circuit voltage of the PV subarray. With real-time photovoltaic power And based on the open-circuit voltage of the photovoltaic subarray With real-time photovoltaic power The MPPT tracking task is executed to generate the photovoltaic operating voltage, which is then used as the constant voltage control voltage at terminal B. Output; When the connection status at terminal B is "battery connected", obtain the battery state of charge (SOC(t)) and base it on the busbar voltage deviation. The battery's state of charge (SOC(t)) is dynamically adjusted using a weighted flexible regulation mechanism based on SOC partitioning to generate the battery-side operating voltage. The battery-side operating voltage is used as the constant voltage control voltage at terminal B. Output; Step S30: Based on the constant voltage control voltage at terminal A and constant voltage control at terminal B A pressure-differential driven coupled analysis mechanism is used to perform the busbar power balance determination task and output a unified energy balance command. Specifically, this includes: Based on constant voltage control at terminal A and constant voltage control at terminal B The average pressure difference was calculated. , Where N is the number of DC-DC modules currently running in the string DC-DC system; When the busbar voltage deviation and When the busbar power is excessive, it is determined that the string DC-DC system is in a state of excess power; the state of excess power means that the busbar needs to absorb power. When the busbar voltage deviation and When the busbar power is insufficient, it is determined that the string DC-DC system is in a state of insufficient busbar power; the state of insufficient busbar power means that the busbar needs to release power. A unified energy balance command is output based on the different states of the string DC-DC system. ; Step S40: Based on the unified energy balance command The battery power reference value generation task is performed using a limiting proportional adjustment mechanism, and the battery reference power is output. ; Step S50: Based on battery reference power A power coordinated regulation mechanism based on grid-connected and off-grid modes is adopted to perform the busbar voltage stabilization control task and output the busbar voltage regulation result set.

2. The microgrid bus voltage control method based on string DC-DC power conversion as described in claim 1, characterized in that, In step S10, ,in This represents the real-time voltage of the DC bus in a string DC-DC system at time t.

3. The microgrid bus voltage control method based on string DC-DC power conversion as described in claim 1, characterized in that, In step S20, the battery-side operating voltage The formula is expressed as: ； in, This is the proportional adjustment coefficient; Battery response weighting factor; Battery response weighting factor The battery state of charge (SOC(t)) is partitioned as follows: ； when When this occurs, it indicates that the battery's state of charge (SOC(t)) has entered the over-sufficient region. ;when When the battery's state of charge (SOC(t)) enters the optimal adjustment range, it indicates that the battery's SOC(t) has reached the optimal adjustment range. When the battery's state of charge (SOC(t)) enters the critical under-discharge zone, it indicates that the battery's SOC(t) has entered the critical under-discharge zone.

4. The microgrid bus voltage control method based on string DC-DC power conversion as described in claim 1, characterized in that, In step S40, based on the unified energy balance command The battery power reference value generation task is performed using a limiting proportional adjustment mechanism, and the battery reference power is output. The steps specifically include: Step S401: When At that time, the upper limit limiting function is used to perform the battery power reference value generation task, and the battery reference power is output. ; ,in, This is an upper limit limiting function; This is the energy absorption adjustment ratio coefficient; This represents the current maximum charging power limit of the battery. Step S402: When At that time, the lower limit limiting function is used to perform the battery power reference value generation task, and the battery reference power is output. ; ,in, This is the lower limit of the battery's current maximum discharge power. This is the proportional coefficient for adjusting the energy release.

5. The microgrid bus voltage control method based on string DC-DC power conversion as described in claim 3, characterized in that, In step S50, based on the battery reference power The steps for implementing busbar voltage stabilization control using a power coordinated regulation mechanism based on grid-connected and off-grid modes, and outputting a set of busbar voltage regulation results, specifically include: Step S501: Obtain the current system operating mode parameters, which include grid-connected operation mode and off-grid operation mode; Step S502: When in grid-connected operation mode: If the busbar voltage deviation And when the battery state of charge (SOC(t)) is greater than the preset battery state of charge threshold, then based on the battery reference power... Instruct the DCAC module to feed power to the grid; If the busbar voltage deviation Based on the battery reference power The DCAC module is instructed to draw energy from the power grid; Step S503: When in off-grid mode: Obtain real-time photovoltaic power. The DCAC module is based on the battery reference power. With real-time photovoltaic power The power supply of the charging pile is dynamically adjusted based on the priority of remaining power supply capacity; Step S504: Output bus voltage regulation result set, which includes grid interaction power, charging pile target power, real-time regulation residual index and bus regulation status identifier.

6. A microgrid bus voltage control system based on string DC-DC power conversion, applied to the microgrid bus voltage control method based on string DC-DC power conversion as described in any one of claims 1 to 5, characterized in that, The microgrid bus voltage control system based on string DC-DC power conversion includes: The busbar voltage deviation acquisition module is used to acquire the voltage at terminal A of the i-th DC-DC module in a string DC-DC system at time t. B-terminal voltage The busbar voltage deviation is calculated based on the nominal value of the DC bus given value. ; A layered weighted constant voltage regulation module is used to regulate voltage based on busbar voltage deviation. A weighted adjustment mechanism based on hierarchical decoupling is used to adjust the voltage at terminal A. B-terminal voltage Perform constant voltage control and output constant voltage control voltage at terminal A. and constant voltage control at terminal B Specifically, this includes: Firstly, based on the busbar voltage deviation For the voltage at terminal A Constant voltage control is achieved using proportional-integral (PI) control, outputting a constant voltage control voltage at terminal A. ; Regarding the voltage at terminal B... Get the B-end connection status of the i-th DC-DC module at time t; When the connection status of terminal B is "PV Connection", obtain the open-circuit voltage of the PV subarray. With real-time photovoltaic power And based on the open-circuit voltage of the photovoltaic subarray With real-time photovoltaic power The MPPT tracking task is executed to generate the photovoltaic operating voltage, which is then used as the constant voltage control voltage at terminal B. Output; When the connection status at terminal B is "battery connected", obtain the battery state of charge (SOC(t)) and base it on the busbar voltage deviation. The battery's state of charge (SOC(t)) is dynamically adjusted using a weighted flexible regulation mechanism based on SOC partitioning to generate the battery-side operating voltage. The battery-side operating voltage is used as the constant voltage control voltage at terminal B. Output; The differential voltage coupling power determination module is used to control the voltage based on the constant voltage at terminal A. and constant voltage control at terminal B A pressure-differential driven coupled analysis mechanism is used to perform the busbar power balance determination task and output a unified energy balance command. Specifically, this includes: Based on constant voltage control at terminal A and constant voltage control at terminal B The average pressure difference was calculated. , Where N is the number of DC-DC modules currently running in the string DC-DC system; When the busbar voltage deviation and When the busbar power is excessive, it is determined that the string DC-DC system is in a state of excess power; the state of excess power means that the busbar needs to absorb power. When the busbar voltage deviation and When the busbar power is insufficient, it is determined that the string DC-DC system is in a state of insufficient busbar power; the state of insufficient busbar power means that the busbar needs to release power. A unified energy balance command is output based on the different states of the string DC-DC system. ; Limiting proportional power generation module, used for unified energy balance command The battery power reference value generation task is performed using a limiting proportional adjustment mechanism, and the battery reference power is output. ; On-grid and off-grid coordinated voltage regulation module, used for battery reference power A power coordinated regulation mechanism based on grid-connected and off-grid modes is adopted to perform the busbar voltage stabilization control task and output the busbar voltage regulation result set.

7. A microgrid bus voltage control device based on string DC-DC power conversion, characterized in that, The microgrid bus voltage control device based on string DC-DC power conversion includes: a memory, a processor, and a microgrid bus voltage control program based on string DC-DC power conversion stored in the memory and executable on the processor. When the microgrid bus voltage control program based on string DC-DC power conversion is executed by the processor, it implements a microgrid bus voltage control method based on string DC-DC power conversion as described in any one of claims 1 to 5.

8. A computer program product, characterized in that, The computer program product includes a microgrid bus voltage control program based on string DC-DC power conversion. When the microgrid bus voltage control program based on string DC-DC power conversion is executed by the processor, it implements a microgrid bus voltage control method based on string DC-DC power conversion as described in any one of claims 1 to 5.

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