A non-impact collaborative control method and system for heterogeneous energy storage module hot plug-in

Abstract

The present application relates to the technical field of modular light storage integrated system control and energy storage management, and discloses a non-impact collaborative control method and system for heterogeneous energy storage module hot plug-in. After detecting that a heterogeneous energy storage module to be connected is inserted, the method sequentially performs communication registration, state parameter acquisition, access feasibility domain determination, pre-charging control, soft parallel control and post-access power redistribution, and performs bypass isolation or fallback control in an abnormal state. The access feasibility domain determination comprehensively considers terminal voltage, state of charge, temperature and equivalent internal resistance difference; the pre-charging control makes the module terminal voltage approach the DC bus voltage; the soft parallel control makes the output current smoothly rise; and the power redistribution determines the power reference value according to the state parameters of each energy storage module. The present application can suppress bus voltage fluctuation and circulating current overshoot during the hot plug-in process, and realize online smooth access and capacity expansion of heterogeneous energy storage modules.

Description

Technical Field

[0001] This invention belongs to the field of modular photovoltaic-energy storage integrated system control and energy storage management technology, specifically relating to a shockless collaborative control method and system for online hot-swappable access of heterogeneous energy storage modules. Background Technology

[0002] With the widespread application of distributed photovoltaic and energy storage systems, modular photovoltaic-energy storage systems are gradually becoming an important development direction for integrated photovoltaic-energy storage systems due to their advantages such as on-demand capacity expansion, flexible deployment, ease of maintenance, and fault isolation. Existing modular photovoltaic-energy storage systems are typically composed of multiple power modules and energy storage modules, and their capacity can be configured and expanded according to load demand and photovoltaic output.

[0003] In practical applications, newly added energy storage modules often differ from existing modules in batch, capacity, aging level, and operating conditions. This results in variations in state of charge, health status, terminal voltage, temperature, and equivalent internal resistance among the modules. When these modules are directly connected to the DC bus with inconsistent parameters, significant bus voltage fluctuations, inter-module circulating current overshoot, and power mismatch can easily occur. In severe cases, this can trigger protection actions, affecting the stable operation of the system.

[0004] Furthermore, existing technologies focus more on the physical pluggable interfaces of energy storage modules, simple pre-charging stages, or static equalization control. They lack integrated design for pre-connection status assessment of heterogeneous energy storage modules, soft parallel adjustment during connection, dynamic power redistribution after connection, and fallback control under abnormal conditions. This makes it difficult to simultaneously address heterogeneous compatibility, smooth connection capability, seamless capacity expansion capability, and system operational reliability. Existing solutions typically struggle to simultaneously achieve pre-connection feasibility assessment, shock-free connection control, post-connection power coordination, and abnormal fallback protection.

[0005] Therefore, how to provide a shock-free collaborative control method and system for hot-swappable access of heterogeneous energy storage modules, so as to reduce the impact of module access, improve heterogeneous compatibility and achieve rapid rollback in abnormal situations, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] Technical problems to be solved

[0007] This invention provides a shockless collaborative control method and system for hot-swappable access of heterogeneous energy storage modules, which solves the technical problems in the prior art that easily cause bus voltage fluctuations, module circulating current overshoot, power mismatch and unsmooth abnormal exit when heterogeneous energy storage modules are connected online.

[0008] Technical solution

[0009] To achieve the above objectives, the present invention provides the following technical solution: a shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules, applied to a modular photovoltaic-energy storage system, wherein the modular photovoltaic-energy storage system includes a DC bus, heterogeneous energy storage modules to be connected, at least one operating energy storage module, at least one power conversion unit, a local controller, a local communication bus, a pre-charge branch, a main power branch, and a bypass branch; the method includes the following steps:

[0010] Step S1: Detect the insertion status of the heterogeneous energy storage module to be connected, establish a communication connection between the heterogeneous energy storage module to be connected and the operating energy storage module, and complete the module identity registration;

[0011] Step S2: Collect the status parameters of the heterogeneous energy storage module to be connected and the energy storage module in operation. The status parameters include at least the state of charge (SOC), state of health (SOH), module terminal voltage, module temperature, and equivalent internal resistance.

[0012] Step S3: Combining the state parameters obtained in step S2 and the DC bus operating status, perform the access feasible region determination for the heterogeneous energy storage module to be connected, and generate pre-charge control parameters and soft parallel control parameters based on the access feasible region determination results; wherein, the access feasible region determination takes into account at least the terminal voltage difference, state of charge difference, temperature difference and equivalent internal resistance difference between the heterogeneous energy storage module to be connected and the operating energy storage module;

[0013] Step S4: When the access feasible region determination result indicates that the heterogeneous energy storage module to be accessed meets the access conditions, combined with the pre-charge control parameters obtained in step S3, the pre-charge control is performed on the heterogeneous energy storage module to be accessed through the pre-charge branch, so that the terminal voltage of the heterogeneous energy storage module to be accessed gradually approaches the DC bus voltage.

[0014] Step S5: When the pre-charge control reaches the preset voltage difference threshold, close the main power branch and, in conjunction with the soft parallel control parameters obtained in step S3, perform soft parallel control on the heterogeneous energy storage module to be connected, so that the reference value of the output current of the heterogeneous energy storage module to be connected gradually changes from the initial value to the target output current, so as to suppress the bus voltage fluctuation and circulating current overshoot at the moment of module connection.

[0015] Step S6: Combined with step S5, complete the operation status after the heterogeneous energy storage modules to be connected are connected, execute the power redistribution control of each energy storage module through local communication, and execute bypass isolation or backoff control when an abnormal state is detected.

[0016] A further technical solution is as follows: In step S1, after detecting the insertion status of the heterogeneous energy storage module to be connected, an auxiliary power supply connection is first established, then a local communication connection is established, and the registration of the module number, rated capacity, rated voltage and operating status identifier is completed.

[0017] A further technical solution is that, in step S2, the state parameters further include at least one of rated capacity, number of cycles, available capacity, temperature rise margin, and available power margin.

[0018] A further technical solution is that, in step S3, the access feasibility domain determination is performed through a comprehensive access index function, which is:

[0019] (1);

[0020] In equation (1), For heterogeneous energy storage modules to be connected Comprehensive access metrics; The voltage at the end of the heterogeneous energy storage module to be connected; This is the DC bus voltage; , , These are the state of charge, temperature, and equivalent internal resistance of the heterogeneous energy storage module to be connected; , , These are the average state of charge, average temperature, and average equivalent internal resistance of the energy storage modules in operation, respectively. , , , These are the corresponding thresholds; , , , These are the weighting coefficients, and ;

[0021] when When, it is determined that the heterogeneous energy storage module to be connected meets the access conditions; when At the same time, the heterogeneous energy storage modules to be connected are kept in a waiting or isolated state.

[0022] A further technical solution is that: in step S4, the pre-charge control is executed through a pre-charge current command, and the pre-charge current command satisfies:

[0023] (2);

[0024] In equation (2), Pre-charge current command for the heterogeneous energy storage module to be connected; Precharge control gain; This is a limiting function; For heterogeneous energy storage modules to be connected at any time The terminal voltage; when the condition is met At that time, the pre-charging is determined to be complete, among which This is a preset voltage difference threshold.

[0025] A further technical solution is that, in step S5, soft parallel control is achieved through gradual adjustment of the output current reference value of the heterogeneous energy storage module to be connected, wherein the output current reference value satisfies:

[0026] (3);

[0027] In equation (3), For heterogeneous energy storage modules to be connected at any time The output current reference value; The target output current; This is the soft parallel adjustment coefficient; The closing time of the main power branch.

[0028] A further technical solution is that, in step S6, the power allocation weights of each energy storage module satisfy the following:

[0029] (4);

[0030] Total power reference value Distribute as follows:

[0031] (5);

[0032] In equations (4) and (5), Assign weights to the power of the energy storage module i to be connected; The available capacity of the energy storage module i to be connected; For reference temperature; to These are the weighting coefficients; The power reference value is the power of the energy storage module i to be connected. This is a reference value for the total power of the system.

[0033] A further technical solution is to perform bypass isolation or backoff control when overvoltage, overcurrent, overtemperature, communication abnormality or insulation abnormality is detected. The bypass isolation or backoff control includes at least one of disconnecting the main power branch, closing the bypass branch, maintaining the pre-charge branch disconnected, and switching the heterogeneous energy storage module to be connected to the isolation state.

[0034] Beneficial effects

[0035] Compared with existing technologies, this invention provides a shockless collaborative control method and system for hot-swappable access of heterogeneous energy storage modules, which has the following advantages:

[0036] 1. This invention determines the feasible access domain and comprehensively evaluates the differences in voltage difference, state of charge, health status, temperature and equivalent internal resistance between the heterogeneous energy storage module to be connected and the operating energy storage module before module connection, thereby reducing the impact risk caused by blind connection.

[0037] 2. By using pre-charge control and soft parallel control, the terminal voltage of the heterogeneous energy storage module to be connected is gradually brought close to the DC bus voltage, and the output current is made to rise smoothly according to the target trajectory, thereby suppressing bus voltage fluctuations and circulating current overshoot.

[0038] 3. By using dynamic power redistribution control based on local communication, energy storage modules with different capacities, aging levels, and operating states can share power according to their state weights, thereby improving the compatibility, capacity utilization, and lifespan balancing effect of heterogeneous energy storage modules.

[0039] 4. By bypassing isolation or backoff control, abnormal modules can be quickly disconnected in case of overvoltage, overcurrent, overtemperature, communication abnormality or insulation abnormality, thereby improving the operational reliability of the modular optical storage system. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the modular photovoltaic energy storage system and the hot-swappable electrical connection architecture of the heterogeneous energy storage module of the present invention;

[0041] Figure 2 This is a flowchart of the impact-free collaborative control method of the present invention;

[0042] Figure 3 This is a schematic diagram of the state machine for the heterogeneous energy storage module to be connected in this invention;

[0043] Figure 4 This is a schematic diagram of the access feasible domain determination process of the present invention;

[0044] Figure 5 This is a timing diagram of the pre-charge control and soft parallel control of the present invention;

[0045] Figure 6 This is a schematic diagram of the power redistribution control after the present invention is connected;

[0046] Figure 7 This is the flowchart of the abnormal rollback control of the present invention;

[0047] Figure 8 This is a comparison diagram of the response of hard access and module integration under the scheme of this invention;

[0048] Figure 9 It is a dynamic response and error convergence diagram of power redistribution of each energy storage module after connection. Detailed Implementation

[0049] The purpose of this invention is to provide a collaborative control method and system capable of suppressing bus voltage fluctuations and inter-module circulating current overshoot when heterogeneous energy storage modules are hot-swapped into a modular photovoltaic-energy storage system. Considering the differences in state of charge, health status, terminal voltage, temperature, and equivalent internal resistance between the heterogeneous energy storage modules to be connected and the operating energy storage modules, this invention first identifies the connection conditions before module connection through a feasible connection domain determination strategy; secondly, it reduces the voltage difference between the heterogeneous energy storage modules to be connected and the DC bus through a pre-charge control scheme; then, it suppresses bus fluctuations and circulating current overshoot at the moment of module connection through a soft parallel control scheme; finally, after module connection, it performs power redistribution control based on the state parameters of each energy storage module, and performs bypass isolation or backoff control in abnormal situations, thereby improving the heterogeneous compatibility, smooth expansion capability, and operational reliability of the modular photovoltaic-energy storage system.

[0050] To make the technical solution of the present invention clearer, the embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the embodiments described are for illustrating the present invention and should not be construed as limiting the scope of protection of the present invention.

[0051] Reference Appendix Figure 1 The modular photovoltaic-storage system of the present invention includes a heterogeneous energy storage module to be connected, an in-operation energy storage module, a power conversion unit, a local controller, a local communication bus, a DC bus, a pre-charge branch, a main power branch, a bypass branch, a photovoltaic side interface, and a load side / grid-connected side interface.

[0052] Both the heterogeneous energy storage modules to be connected and those already in operation can be connected to the DC bus via a pre-charge branch, a main power branch, and a bypass branch. The pre-charge branch reduces the voltage difference between the heterogeneous energy storage module to be connected and the DC bus before the module is connected; the main power branch enables the module to operate normally after the connection conditions are met; and the bypass branch enables bypass or isolation control of the module when an abnormal state is detected. Each local controller interacts with other controllers via a local communication bus and works in conjunction with the power conversion unit to complete module connection control and system power regulation.

[0053] In this embodiment, a heterogeneous energy storage module refers to an energy storage module that differs from an operational energy storage module in at least one of the following parameters: rated capacity, rated voltage, state of charge, state of health, terminal voltage, temperature, equivalent internal resistance, cycle count, or available capacity. These differences may arise from different module batches, different capacity configurations, different degrees of aging, or different operating conditions.

[0054] Reference Appendix Figure 2 The shockless collaborative control method of the present invention includes module insertion detection and communication registration, status parameter acquisition, access feasible domain determination, pre-charge control, soft parallel control, power redistribution and abnormal backoff control.

[0055] When the heterogeneous energy storage module to be connected is inserted into the standardized hot-swappable interface, the local controller first detects the insertion status and establishes auxiliary power supply and local communication connections. Preferably, the local communication bus uses a CAN bus, where CAN is the controller's local area network; other peer-to-peer communication buses can also be used.

[0056] In this step, the heterogeneous energy storage module to be connected broadcasts its module number, rated capacity, rated voltage, current SOC, current SOH, and alarm flag information to the system; the operating energy storage module in the system provides feedback on its current operating status, thereby completing the communication registration and identification of the heterogeneous energy storage module to be connected.

[0057] Step S2 involves collecting the status parameters of the heterogeneous energy storage module to be connected and the energy storage module in operation, obtaining information on SOC, SOH, terminal voltage, temperature, and equivalent internal resistance.

[0058] After communication registration is completed, the local controller collects the status parameters of the heterogeneous energy storage modules to be connected and the energy storage modules in operation. These status parameters include at least: State of Charge (SOC), State of Health (SOH), module terminal voltage U, module temperature T, and equivalent internal resistance R. Preferably, rated capacity, cycle count, temperature rise margin, and available capacity may also be collected.

[0059] Among them, SOC is used to characterize the current remaining power status of the energy storage module; SOH is used to characterize the health status or aging degree of the energy storage module; module terminal voltage U is used to determine the voltage difference between the module and the DC bus; module temperature T is used to determine the thermal safety status of the energy storage module; and equivalent internal resistance R is used to reflect the current surge risk and aging status of the energy storage module.

[0060] Step S3 involves combining the state parameters obtained in step S2 and the bus operating status to perform access feasible region determination and generate pre-charge control parameters and soft parallel control parameters. To avoid excessive impact when heterogeneous energy storage modules are directly connected to the DC bus, this invention uses a comprehensive access index function to perform access feasible region determination for the heterogeneous energy storage modules to be connected, as shown in equation (1).

[0061] (1);

[0062] In equation (1), For heterogeneous energy storage modules to be connected Comprehensive access metrics; The voltage at the end of the heterogeneous energy storage module to be connected; This is the DC bus voltage; , , These are the state of charge, temperature, and equivalent internal resistance of the heterogeneous energy storage module to be connected; , , These are the average state of charge, average temperature, and average equivalent internal resistance of the energy storage modules in operation, respectively. , , , These are the corresponding thresholds; , , , These are the weighting coefficients, and

[0063] ;

[0064] when When, it is determined that the heterogeneous energy storage module to be connected meets the access conditions; when If the system determines that the heterogeneous energy storage module to be connected does not yet meet the access conditions, the local controller maintains it in a waiting or isolated state. Thus, the system can identify the state differences between the module to be connected and the module already in operation before closing the main power branch.

[0065] In this embodiment, the precharge control parameters include at least the precharge control gain and the preset voltage difference threshold; the soft parallel control parameters include at least the target output current, the soft parallel adjustment coefficient, and the closing time of the main power branch.

[0066] In a preferred embodiment, to facilitate the description of the control objectives during the online integration process of the heterogeneous energy storage modules to be connected, the following error variables are defined:

[0067] (6);

[0068] (7);

[0069] (8);

[0070] in, The voltage difference error between the terminal voltage of the heterogeneous energy storage module to be connected and the DC bus voltage; The current tracking error between the actual output current and the target output current of the heterogeneous energy storage module to be connected; This represents the power distribution error between the actual output power of the energy storage module i to be connected and the target power reference value.

[0071] The control objectives of this invention include: after the access determination is passed, the differential voltage error enters the preset voltage difference threshold range within a preset time; after the main power branch is closed, the current tracking error is smoothly reduced to the preset error range; after the module is connected and running, the power distribution error is converged to the vicinity of the corresponding target power reference value, thereby realizing the smooth connection and coordinated operation of heterogeneous energy storage modules.

[0072] Step S4 involves combining the judgment result obtained in step S3 with the pre-charge control parameters to execute pre-charge control through the pre-charge branch. After the heterogeneous energy storage module to be connected meets the access conditions, the local controller controls the pre-charge branch to be turned on to execute pre-charge control on the heterogeneous energy storage module to be connected. Preferably, the pre-charge control adopts the pre-charge current command shown in equation (2).

[0073] (2);

[0074] In equation (2), Pre-charge current command for the heterogeneous energy storage module to be connected; Precharge control gain; This is a limiting function; For heterogeneous energy storage modules to be connected at any time The terminal voltage; when the condition is met At that time, the pre-charging is determined to be complete, among which A preset voltage difference threshold is set. Through the above pre-charge control, the voltage at the end of the heterogeneous energy storage module to be connected gradually approaches the DC bus voltage, thereby reducing the voltage difference and inrush current at the moment the main power branch is closed.

[0075] In a preferred embodiment, the pre-charge control satisfies the finite-time completion condition. To ensure that the terminal voltage of the heterogeneous energy storage module to be connected approaches the DC bus voltage within a finite time, the pre-charge current command can also be written as follows, based on equation (2):

[0076] (9);

[0077] In equation (9), , For pre-charge feedback gain, It is a fractional power exponent and satisfies , The sign function is used. Since the pre-charge current command includes both linear and fractional power feedback terms, the differential pressure error... It can reach the voltage difference threshold within a limited time. The corresponding bounded region.

[0078] Furthermore, there exists a preset upper bound for the time. , making when When satisfied:

[0079] (10);

[0080] In equation (10), This sets the upper limit for the pre-charge completion time. By setting the upper limit for the pre-charge completion time, the heterogeneous energy storage module to be connected can enter the main power branch closing stage only after meeting the safe differential pressure condition.

[0081] Step S5 involves closing the main power branch and executing soft parallel control based on the soft parallel control parameters obtained in step S3. After pre-charging is completed and the preset voltage difference threshold is met, the main power branch is closed, allowing the heterogeneous energy storage module to be connected to the DC bus. To avoid circulating current overshoot during connection, the heterogeneous energy storage module to be connected adopts the gradually changing output current reference value shown in equation (3), so that its output current gradually transitions from the initial value to the target value.

[0082] (3);

[0083] In equation (3), For heterogeneous energy storage modules to be connected at any time The output current reference value; The target output current; This is the soft parallel adjustment coefficient; This refers to the moment when the main power branch closes. By making the output current of the heterogeneous energy storage module to be connected track the output current reference value, the peak circulating current and bus voltage disturbance at the moment the module is connected can be reduced.

[0084] In a preferred embodiment, the soft parallel control satisfies the finite-time smooth connection requirement. The current tracking error is defined as:

[0085] (11);

[0086] In equation (11), The actual output current of the heterogeneous energy storage module to be connected. The target output current trajectory.

[0087] Furthermore, there exists a preset upper bound for the time. , making when When satisfied:

[0088] (12);

[0089] In equation (12), For the allowable error of current, This is the upper bound of the soft parallel connection completion time. Therefore, heterogeneous energy storage modules to be connected can be smoothly integrated within a finite time.

[0090] Reference Appendix Figure 5 Pre-charge control and soft parallel control are executed sequentially according to time. to During the pre-charging phase, the pre-charging branch is in a conducting state, and the terminal voltage of the heterogeneous energy storage module to be connected is... Gradually approaching the DC bus voltage The corresponding pre-charge current It gradually decays as the voltage difference decreases; when it satisfies At that time, the pre-charging is considered complete. Then... The module output current is constantly closed and enters the soft parallel phase. The current gradually increases from the initial value to the target output current. This enables the smooth integration and operation of heterogeneous energy storage modules to be connected.

[0091] Step S6 combines step S5 to complete the operation status after the module is integrated, and performs power redistribution control and abnormal bypass back-off control.

[0092] Reference Appendix Figure 6 After the heterogeneous energy storage modules are connected to the system, each energy storage module sends its state of charge, health status, temperature, equivalent internal resistance, and available capacity to the dynamic power redistribution control unit. The dynamic power redistribution control unit calculates the power allocation weight based on the state parameters of each energy storage module. In conjunction with the system's total power reference value Generate power reference values ​​for each energy storage module. Then, the corresponding power reference value is sent to the local controller of each module, thereby realizing dynamic power redistribution control under the mixed operation conditions of heterogeneous energy storage modules.

[0093] The power allocation weights of each energy storage module satisfy the following:

[0094] (4);

[0095] Total power reference value Distribute as follows:

[0096] (5);

[0097] In equations (4) and (5), Assign weights to the power of the energy storage module i to be connected; The available capacity of the energy storage module i to be connected; For reference temperature; to These are the weighting coefficients; The power reference value is the power of the energy storage module i to be connected. The total power of the system is the reference value. As can be seen from equation (4), the energy storage module with better health, higher available capacity and lower risk of temperature rise bears higher power; the energy storage module with poorer health, higher equivalent internal resistance or higher temperature bears lower power, thereby achieving smooth power distribution and balanced lifespan when heterogeneous energy storage modules are mixed and operated.

[0098] In a preferred embodiment, the local controllers of each energy storage module constitute peer-to-peer cooperative control nodes. The local controllers of each energy storage module exchange status parameters via a local communication bus and perform distributed power redistribution control based on neighbor node information. Let the... The set of neighbor nodes corresponding to each local controller is: Then its power reference value update law can be expressed as:

[0099] (13);

[0100] In equation (13), For the first The estimated power reference value currently maintained by each local controller. For the first The node and the first The communication weight between nodes For local correction gain, The target power reference value is calculated according to equations (4) and (5). Through the above update law, each local controller achieves consistent and coordinated updating of the power reference value under local communication conditions, so that each energy storage module can still achieve smooth power distribution under heterogeneous parameter conditions.

[0101] In a preferred embodiment, when overvoltage, overcurrent, overtemperature, communication anomaly, or insulation anomaly is detected, the local controller immediately performs bypass isolation or backoff control. Preferably, the anomaly triggering condition is met:

[0102] (14);

[0103] when When an abnormality occurs, the abnormal backoff control is triggered. The local controller disconnects the main power branch and controls the bypass branch to close or maintain the module isolation state according to the type of abnormality, so as to prevent the abnormal module from affecting the normal operation of the DC bus and other operating energy storage modules.

[0104] Reference Appendix Figure 7 When the system detects an abnormal state, it first performs anomaly detection and determines the type of anomaly. The anomaly types include overvoltage, overcurrent, overtemperature, communication anomalies, and insulation anomalies. Once any anomaly type is determined, the system disconnects the main power branch and, depending on the anomaly, closes the bypass branch or switches to isolation mode. Subsequently, it outputs an alarm message and returns to the waiting state or ends the rollback process.

[0105] In a preferred embodiment, the precharge control and soft parallel control are non-vulnerable. This is because the precharge control gain and soft parallel adjustment coefficient are subject to parameter perturbations, i.e.:

[0106] (15);

[0107] In equation (15), To precharge the control gain perturbation, This represents the perturbation of the soft parallel control coefficient. Under the condition that the parameter perturbation is bounded, the differential pressure error in the pre-charge stage and the current tracking error in the soft parallel stage remain bounded and can enter their respective allowable error ranges, thus demonstrating that the control scheme described in this invention is non-vulnerable.

[0108] Reference Appendix Figure 3 The connection process for heterogeneous energy storage modules includes the following states: idle, inserted, registered, under judgment, pre-charging, soft parallel connection, parallel operation, abnormal rollback, and isolation. When a module insertion is detected, the system switches from idle to inserted; after completing communication registration, it enters the registered state and then the under judgment state; when the connection judgment passes, it enters the pre-charging state; after pre-charging is completed and the voltage difference threshold is met, it enters the soft parallel connection state; after the main branch is closed and soft parallel connection is completed, it enters the parallel operation state; if an abnormality is triggered in the pre-charging, soft parallel, or parallel operation states, it switches to the abnormal rollback state; after disconnecting the main branch and completing bypass or isolation, it enters the isolation state; when the module is reset or physically removed, the system returns to idle.

[0109] Reference Appendix Figure 4 The feasibility domain determination process first collects the terminal voltage of the heterogeneous energy storage module to be connected. State of charge ,temperature and equivalent internal resistance The comprehensive access index is calculated by combining the status parameters and the operating status of the DC bus. .when When the heterogeneous energy storage module to be connected is determined to meet the access conditions, it enters the pre-charging stage; when If the heterogeneous energy storage module to be connected does not meet the access conditions, it will remain in a waiting or isolated state.

[0110] In a preferred embodiment, to analyze the overall stability of the control scheme, the following Lyapunov function is constructed, whereby the Lyapunov function is a function used to characterize the energy of the system error:

[0111] (16);

[0112] In equation (16), These are weighting coefficients. The number of energy storage modules participating in power redistribution. Under the action of the designed pre-charge control law, soft parallel control law, and power redistribution control law, the derivative of the Lyapunov function satisfies:

[0113] (17);

[0114] In equation (17), , , It is a positive coefficient. , For exponential parameters, This is a bounded disturbance term. Therefore, it can be seen that under the condition of bounded disturbance, the differential pressure error, current tracking error, and power distribution error all remain bounded.

[0115] Furthermore, within the permitted access area, if the error system satisfies the following contraction condition:

[0116] (18);

[0117] In equation (18), It is a symmetric positive definite metric matrix. For system state variables, For time variables, For the error system matrix, The shrinkage rate indicates that the distance between error trajectories decreases over time, thereby enhancing the local convergence and trajectory robustness of the process of integrating heterogeneous energy storage modules.

[0118] Reference Appendix Figure 8 Compared to the hard-access solution, the present invention can significantly reduce the DC bus voltage fluctuation amplitude and effectively suppress the peak output current of the module during the connection of the heterogeneous energy storage module, thereby reducing the impact of the module connection moment.

[0119] Reference Appendix Figure 9 After the heterogeneous energy storage modules are connected to the system, the output power of each energy storage module is redistributed to the new target power reference value; the power redistribution error is within a finite time. Entering the preset error threshold Within the corresponding range, it indicates that the dynamic power redistribution control described in this invention can enter the stable redistribution error band within a finite time.

[0120] The improvements of this invention mainly include: an access feasible domain determination strategy based on heterogeneous state parameters; a shockless access strategy combining pre-charge control and soft parallel control; a dynamic power redistribution strategy based on local communication; and a bypass isolation and backoff control strategy for abnormal operating conditions.

[0121] The beneficial effects of adopting the above technical solution are as follows: the present invention can identify the state differences between the heterogeneous energy storage module to be connected and the operating energy storage module before module connection through the access feasible domain determination strategy, thereby reducing the impact risk caused by blind connection; through the combination of pre-charge control and soft parallel control, it can effectively suppress bus voltage fluctuations and circulating current overshoot at the moment of module connection; through dynamic power redistribution control based on local communication, it can improve the compatibility and utilization rate of energy storage modules of different batches, capacities and aging degrees; through bypass isolation or backoff control, it can quickly disconnect abnormal modules in the event of overvoltage, overcurrent, overtemperature, communication abnormality or insulation abnormality, thereby improving the reliability of system operation.

[0122] To facilitate a comprehensive understanding of the technical solution of this invention, the technical concept is summarized and briefly described below. This invention addresses the problems of bus fluctuations, circulating current overshoot, and power mismatch that easily arise when heterogeneous energy storage modules are hot-swapped into modular photovoltaic-energy storage systems due to differences in state of charge, health status, terminal voltage, temperature, and equivalent internal resistance between the module to be connected and the operating module. It proposes a shockless collaborative control scheme that combines feasible access domain determination, pre-charge control, soft parallel control, power redistribution control, and abnormal bypass backoff control. First, upon detecting the insertion of a heterogeneous energy storage module to be connected, a communication connection is established between it and the operating module, and module registration is completed. Second, the status parameters of the module to be connected and the operating module are collected, and the access feasibility domain is determined in conjunction with the bus operating status, generating pre-charge control parameters and soft parallel control parameters. Then, pre-charge control is executed through the pre-charge branch to gradually bring the voltage at the end of the module to be connected close to the DC bus voltage. After pre-charging is completed, the main power branch is closed to execute soft parallel control to suppress bus voltage fluctuations and circulating current overshoot at the moment of module connection. Finally, after the module is connected, power redistribution control is executed in conjunction with the operating status of each energy storage module, and bypass isolation or back-off control is executed in abnormal conditions, thereby realizing smooth online connection of heterogeneous energy storage modules and shockless expansion of system capacity.

Claims

1. A shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules, characterized in that: The method is applied to a modular photovoltaic-energy storage system, which includes a DC bus, heterogeneous energy storage modules to be connected, at least one operating energy storage module, at least one power conversion unit, a local controller, a local communication bus, a pre-charge branch, a main power branch, and a bypass branch; the method includes the following steps: S1: Detect the insertion status of the heterogeneous energy storage module to be connected, establish a communication connection between the heterogeneous energy storage module to be connected and the operating energy storage module, and complete the module identity registration; S2: Collect the status parameters of the heterogeneous energy storage module to be connected and the energy storage module in operation. The status parameters include at least the state of charge (SOC), state of health (SOH), module terminal voltage, module temperature, and equivalent internal resistance. S3: Combining the state parameters obtained in step S2 and the DC bus operating status, perform the access feasible region determination for the heterogeneous energy storage module to be connected, and generate pre-charge control parameters and soft parallel control parameters based on the access feasible region determination result; wherein, the access feasible region determination takes into account at least the terminal voltage difference, state of charge difference, temperature difference and equivalent internal resistance difference between the heterogeneous energy storage module to be connected and the operating energy storage module. S4: When the access feasible region determination result indicates that the heterogeneous energy storage module to be accessed meets the access conditions, combined with the pre-charge control parameters obtained in step S3, the pre-charge control is performed on the heterogeneous energy storage module to be accessed through the pre-charge branch, so that the terminal voltage of the heterogeneous energy storage module to be accessed gradually approaches the DC bus voltage. S5: When the pre-charge control reaches the preset voltage difference threshold, close the main power branch and, in conjunction with the soft parallel control parameters obtained in step S3, perform soft parallel control on the heterogeneous energy storage module to be connected, so that the reference value of the output current of the heterogeneous energy storage module to be connected gradually changes from the initial value to the target output current, so as to suppress the bus voltage fluctuation and circulating current overshoot at the moment of module connection. S6: Combined with step S5, complete the operation status after the heterogeneous energy storage modules to be connected are connected, execute the power redistribution control of each energy storage module through local communication, and execute bypass isolation or backoff control when an abnormal state is detected.

2. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 1, characterized in that: In step S1, after detecting the insertion status of the heterogeneous energy storage module to be connected, an auxiliary power supply connection is first established, then a local communication connection is established, and the module number, rated capacity, rated voltage and operating status identifier are registered.

3. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 1, characterized in that: In step S2, the status parameters further include at least one of rated capacity, number of cycles, available capacity, temperature rise margin, and available power margin.

4. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 1, characterized in that: In step S3, the access feasibility domain determination is performed using a comprehensive access index function, which is: ； In the formula, For heterogeneous energy storage modules to be connected Comprehensive access metrics; The voltage at the end of the heterogeneous energy storage module to be connected; This is the DC bus voltage; , , These are the state of charge, temperature, and equivalent internal resistance of the heterogeneous energy storage module to be connected; , , These are the average state of charge, average temperature, and average equivalent internal resistance of the energy storage modules in operation, respectively. , , , These are the corresponding thresholds; , , , These are the weighting coefficients, and ; when When, it is determined that the heterogeneous energy storage module to be connected meets the access conditions; when At the same time, the heterogeneous energy storage modules to be connected are kept in a waiting or isolated state.

5. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 4, characterized in that: In step S4, the pre-charge control is executed through a pre-charge current command, which satisfies the following: ； In the formula, Pre-charge current command for the heterogeneous energy storage module to be connected; Precharge control gain; This is a limiting function; For heterogeneous energy storage modules to be connected at any time The terminal voltage; when the condition is met At that time, the pre-charging is determined to be complete, among which This is a preset voltage difference threshold.

6. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 5, characterized in that: In step S5, soft parallel control is achieved by gradually adjusting the output current reference value of the heterogeneous energy storage module to be connected, wherein the output current reference value satisfies: ； In the formula, For heterogeneous energy storage modules to be connected at any time The output current reference value; The target output current; This is the soft parallel adjustment coefficient; The closing time of the main power branch.

7. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 6, characterized in that: In step S6, the power allocation weights of each energy storage module satisfy the following: ； Total power reference value Distribute as follows: ； In the formula, The health status of the heterogeneous energy storage module i to be connected. Assign weights to the power of the energy storage module i to be connected; The available capacity of the energy storage module i to be connected; For reference temperature; to These are the weighting coefficients; The power reference value is the power of the energy storage module i to be connected. This is a reference value for the total power of the system.

8. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 1, characterized in that: In step S6, when overvoltage, overcurrent, overtemperature, communication abnormality, or insulation abnormality is detected, bypass isolation or backoff control is executed. The bypass isolation or backoff control includes at least one of disconnecting the main power branch, closing the bypass branch, maintaining the pre-charge branch disconnected, and switching the heterogeneous energy storage module to be connected to the isolation state.

9. The shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules according to claim 4, characterized in that: When multiple heterogeneous energy storage modules are inserted simultaneously, the comprehensive access index function applies. The access feasible domain determination, pre-charge control, and soft parallel control are executed in ascending order.

10. A modular photovoltaic energy storage system, characterized in that: It includes a heterogeneous energy storage module to be connected, at least one operating energy storage module, a power conversion unit, a local controller, a local communication bus, a pre-charge branch, a main power branch, a bypass branch, and a DC bus. The local controller is configured to execute a shockless collaborative control method for hot-swappable access of heterogeneous energy storage modules as described in any one of claims 1 to 9. The precharge branch includes a precharge switch and a precharge resistor, the main power branch includes a main power switch, and the bypass branch includes a bypass switch or an isolating switch. The local controller is connected to the precharge switch, the main power switch, and the bypass switch respectively, and is used to control the on / off state of the corresponding branch according to the access status.

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