Three-phase unbalance regulation energy scheduling method and energy storage system

Abstract

The application discloses a three-phase imbalance regulation energy scheduling method and an energy storage system. The method comprises the following steps: determining a load distribution method according to the comparison between the total load power and the rated total power, and obtaining the final load of each phase; calculating the three-phase imbalance degree according to the final load, and performing normalization processing on the three-phase imbalance degree to obtain the global imbalance degree coefficient of each phase; transmitting the global imbalance degree coefficient of each phase from the main inverter to each slave inverter; and each slave inverter calculates the three-phase imbalance regulation instruction for local energy regulation by combining the global imbalance degree coefficient of each phase with the rated power of the slave inverter. The energy storage system is used to implement the three-phase imbalance regulation energy scheduling method. The application has the beneficial effects that the load distribution is taken as the basis, the imbalance treatment is taken as the target, the synchronization of the load safety and the imbalance treatment accuracy is achieved, and the system operation stability and adaptability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy power generation, in particular to a three-phase imbalance regulation energy scheduling method and an energy storage system. BACKGROUND

[0002] In the operation process of a three-phase energy storage system, the core requirement is to realize stable load bearing while solving the three-phase imbalance problem. The current mainstream technical solutions in the industry mainly fall into two categories:

[0003] (1) Load distribution solution: The "average distribution method" or "proportional distribution method according to total power" is mostly used, which directly distributes the total load of the system to the A, B and C phases in an average manner, or only distributes the load according to the rated power of each slave machine, without considering the actual maximum bearing capacity of each phase (such as the upper limit of inverter power and the line bearing limit); when the total load of the system approaches or exceeds the maximum bearing capacity of a certain phase, only the total output power is simply limited, without forming a distribution load logic; this may cause the single-phase load to exceed its bearing limit, causing inverter overload, line overheating and other faults, and even affecting the stability of parallel operation of the system.

[0004] (2) Three-phase imbalance regulation solution, including host unified regulation and slave independent regulation. For the host unified regulation, the host calculates the three-phase imbalance degree and directly issues a unified imbalance compensation instruction to each slave machine without considering the rated power difference of each slave machine; the unified compensation instruction after distribution may cause the overload of the slave machine with small rated power and the underutilization of the regulation capacity of the slave machine with large rated power. For the slave independent regulation, each slave machine independently regulates based on the locally collected three-phase data, which is prone to regulation conflicts, leading to an increase in the overall imbalance degree of the system. For example, some solutions use a fixed coefficient to distribute the imbalance compensation amount, which cannot adapt to scenarios with large differences in rated power of the slave machines, and is prone to cause the power difference between two phases of a slave machine to exceed the stress of the machine, causing an overload fault.

[0005] At the same time, in the face of load step changes (such as the sudden access of a single-phase high-power load) or slave machine state fluctuations (such as temporary derating of a certain slave machine), the existing solutions have no linkage regulation mechanism, and cannot quickly adjust the load distribution strategy and imbalance compensation instruction, which is prone to cause fluctuations in the operation of the system. SUMMARY

[0006] One of the purposes of the present application is to provide a three-phase imbalance regulation energy scheduling method that can solve at least one of the defects in the background art.

[0007] Another purpose of the present application is to provide an energy storage system that can solve at least one of the defects in the background art.

[0008] To achieve at least one of the above objectives, the technical solution adopted in this application is as follows: a three-phase imbalance regulation energy dispatch method, applied to a multi-inverter system with a master control architecture, comprising the following steps: obtaining the actual load of each phase of the system and calculating the total three-phase load power; comparing the total three-phase load power with the rated total power; wherein, the rated total power is equal to the sum of the rated power of the master inverter and the rated power of each slave inverter; when the total three-phase load power is less than or equal to the rated total power, using a first load allocation method to determine the final load of each phase; and when the total three-phase load power is less than or equal to the rated total power, using a first load allocation method to determine the final load of each phase; When the load power exceeds the rated total power, the second load distribution method is used to determine the final load of each phase. Based on the three-phase average load and the final load of each phase, the three-phase unbalance is calculated, and the three-phase unbalance is normalized using the sum of the rated power of all inverters as a benchmark to obtain the global unbalance coefficient of each phase. The global unbalance coefficient of each phase is transmitted from the master inverter to each slave inverter, so that each slave inverter can calculate the local three-phase unbalance regulation command for energy regulation by combining the global unbalance coefficient of each phase with its own rated power.

[0009] Preferably, the process of determining the final load of each phase using the first load distribution method is as follows: if the total load power of the three phases is less than or equal to the rated total power, the basic load of each phase is determined according to the maximum bearing capacity of each phase; based on the basic load of each phase, the total remaining load of the system and the total remaining bearing capacity of each phase are calculated, and the total remaining load is distributed according to the total remaining bearing capacity of each phase to obtain the final load of each phase.

[0010] Preferably, the determination of the base load includes the following process: if the actual load of a phase is less than or equal to the maximum load of the corresponding phase, the actual load of that phase is taken as the base load; if the actual load of a phase is greater than the maximum load of the corresponding phase, the maximum load of that phase is taken as the base load.

[0011] Preferably, the calculation of the final load includes the following process: if the calculated total remaining load is less than or equal to zero, the final load of each phase is equal to the foundation load of each phase; if the calculated total remaining load is greater than zero, the total remaining load is allocated according to the proportion of the total remaining load of each phase to obtain the remaining allocation amount of each phase; the remaining allocation amount of each phase is added to the foundation load to obtain the final load of each phase.

[0012] Preferably, the calculation of the final load includes the following process: if the calculated total remaining load is less than or equal to zero, the final load of each phase is equal to the basic load of each phase; if the calculated total remaining load is greater than zero, the rated power of each phase is calculated and the rated power ratio of each phase is calculated; the rated power ratio of each phase is multiplied by the total remaining load of the corresponding phase to obtain the rated power weight of each phase; the total remaining load is allocated based on the ratio of the rated power weight of each phase to obtain the remaining allocation amount of each phase; the remaining allocation amount of each phase is added to the basic load to obtain the final load of each phase.

[0013] Preferably, the unbalance degree of each phase is calculated based on the difference between the final load of each phase and the average load of the three phases; the global unbalance degree coefficient of each phase is obtained by dividing the unbalance degree of each phase by the sum of the rated power of all inverters.

[0014] Preferably, the global imbalance coefficients of the three phases are multiplied by the rated power of the inverter to obtain the three-phase imbalance regulation command required for energy regulation.

[0015] Preferably, during the power regulation process of the inverter, the inverter power reference for each corresponding phase in the control loop is obtained by superimposing the generated three-phase imbalance regulation command with the three-phase equally distributed inverter power command; wherein, the inverter power command is equal to the total input power of the inverter.

[0016] Preferably, the process of determining the final load of each phase using the second load distribution method is as follows: Based on the rated total power, the average power of the three phases is calculated, and the average power of the three phases is used as the final load of each phase.

[0017] An energy storage system for implementing the above-mentioned three-phase imbalance regulation energy dispatch method includes multiple energy storage inverters; one of the energy storage inverters acts as a master, and the remaining multiple energy storage inverters act as slaves; the master is used for global status monitoring and calculation of the global imbalance coefficient, and the master is adapted to send the obtained global imbalance coefficient to all the slaves; the slaves calculate the three-phase imbalance regulation command based on the received global imbalance coefficient.

[0018] Compared with the prior art, the beneficial effects of this application are as follows:

[0019] This application is based on load distribution and aims at imbalance management. Through the coherent logic of "load acquisition - load distribution - imbalance coefficient calculation - inverter execution", it achieves the simultaneous attainment of load safety and the accuracy of imbalance management, thereby improving the system's operational stability and adaptability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall working steps of this application.

[0021] Figure 2 A schematic diagram of the energy regulation control process for this application.

[0022] Figure 3 This is a schematic diagram of the energy storage system architecture in this application.

[0023] Figure 4 This is a schematic diagram illustrating the working process of the host and slave devices in this application. Detailed Implementation

[0024] The present application will now be further described in conjunction with specific embodiments. It should be noted that, in the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0025] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0026] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0027] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0030] One aspect of this application provides a three-phase imbalance regulation energy dispatch method, applied to a multi-inverter system with a main control architecture, such as... Figure 1 As shown, one preferred embodiment includes the following steps: obtaining the actual load of each phase of the system and calculating the total three-phase load power. Comparing the total three-phase load power with the rated total power; wherein the rated total power is equal to the sum of the rated power of the main inverter and the rated power of each slave inverter. When the total three-phase load power is less than or equal to the rated total power, a first load allocation method is used to determine the final load of each phase. When the total three-phase load power is greater than the rated total power, a second load allocation method is used to determine the final load of each phase. Calculating the three-phase unbalance based on the average three-phase load and the final load of each phase, and normalizing the three-phase unbalance based on the sum of the rated power of all inverters to obtain the global unbalance coefficient of each phase. Transmitting the global unbalance coefficient of each phase to each slave inverter through the main inverter, so that each slave inverter can calculate the local three-phase unbalance regulation command for energy regulation by combining the global unbalance coefficient of each phase with its own rated power.

[0031] It is understandable that the core of the technical solution in this application is based on load distribution and aims at imbalance management. Through the coherent logic of "load acquisition - load distribution - imbalance coefficient calculation - inverter execution", it achieves the simultaneous attainment of load safety and the accuracy of imbalance management, thereby improving the stability and adaptability of system operation.

[0032] Specifically, the system first determines the relationship between the total three-phase load power and the rated total power. Then, it achieves safe load distribution across the three phases through a combination of "basic distribution" and "residual distribution." Basic distribution ensures that no single phase is overloaded, while residual distribution maximizes the utilization of each phase's load capacity, resulting in the final load command for each phase. Based on the load distribution results, the three-phase imbalance is calculated, and then decomposed according to a "globally uniform ratio," avoiding inverter compatibility issues caused by direct average distribution. This means that inverters with lower rated power will not overload due to excessive compensation, while the adjustment capabilities of inverters with higher rated power can be fully utilized, achieving efficient reduction of the overall system imbalance. When faced with sudden load changes (such as sudden single-phase load changes) or inverter status fluctuations (such as temporary derating), the load distribution stage can quickly recalculate the load command for each phase, and the imbalance decomposition stage synchronously updates the global imbalance coefficient. Each inverter adapts and adjusts in real time, ensuring the system responds quickly to disturbances and maintains stable operation. It can be applied to scenarios where inverters with different rated power are connected in parallel. Through the logic of "normalization coefficient + local calculation", there is no need to design adjustment strategies for different inverters, which reduces the system deployment and debugging costs.

[0033] In this embodiment, the system can collect the actual loads PloadA, PloadB, and PloadC of the three phases A, B, and C of the inverter system through the communication network; at this time, the actual loads of the three phases can be added together to obtain the total three-phase load power of the system Pload_sum = PloadA + PloadB + PloadC.

[0034] In this embodiment, after calculating the total three-phase load power Pload_sum, the obtained total three-phase load power Pload_sum can be compared with the system's set rated total power Pn_total, and the load-bearing strategy can be determined based on the comparison result. Specifically, if Pload_sum > Pn_total, it means that the system is currently operating under overload. In order to ensure the safe operation of the system, it is necessary to perform load-limited operation with full power, that is, the total three-phase load PpcsForLoad_total = Pn_total. If Pload_sum ≤ Pn_total, it means that the system is theoretically operating normally, and the total three-phase load PpcsForLoad_total = Pload_sum.

[0035] Understandably, the scheduling method for three-phase imbalance regulation differs depending on the system's operating state. For a system operating under overload conditions, each inverter is theoretically already at full load or overload, meaning the inverters have no additional capacity for imbalance regulation. Therefore, the system can only distribute the total three-phase load power according to the principle of "average distribution + single-phase limiting," ensuring that each phase does not exceed its maximum single-phase load. For a system operating under normal conditions, some inverters still possess a certain load-bearing capacity; therefore, the total three-phase load power is distributed in a tiered manner based on three-phase imbalance regulation. For ease of understanding, the following will describe in detail the distribution process of the total three-phase load power for the two operating states of the system.

[0036] Example 1:

[0037] For a system with overloaded three-phase total load power Pload_sum, the process of allocating the three-phase total load power Pload_sum using the second load distribution method is as follows: Based on the rated total power Pn_total, the average three-phase power is calculated as Pn_total / 3, and this average three-phase power Pn_total / 3 is used as the final load PpcsForLoad_X for each phase; where X = {A, B, C}. Since the system is already in a non-ideal state of load-limited operation, priority should be given to ensuring safe operation; therefore, no further three-phase imbalance control is required in this scenario.

[0038] Example 2:

[0039] For a system with a normal three-phase total load power Pload_sum, the process of allocating the three-phase total load power Pload_sum using the first load distribution method is as follows: If the three-phase total load power Pload_sum is less than or equal to the rated total power Pn_total, the basic load Pload_X_base of each phase is determined based on the maximum carrying capacity Pmax of each phase. Based on the basic load Pload_X_base of each phase, the total remaining load Premain of the system and the total remaining load Premain_X of each phase are calculated, and the total remaining load Premain is allocated according to the total remaining load Premain_X of each phase to obtain the final load PpcsForLoad_X of each phase; where X={A, B, C}.

[0040] In this embodiment, the determination of the base load Pload_X_base needs to ensure that the load of a single phase does not exceed its maximum load Pmax_X; the specific allocation process of the base load Pload_X_base is as follows: if the actual load PloadX of a certain phase is less than or equal to the maximum load Pmax_X of the corresponding phase, the actual load PloadX of that phase is used as the base load Pload_X_base; if the actual load PloadX of a certain phase is greater than the maximum load Pmax_X of the corresponding phase, the maximum load Pmax_X of that phase is used as the base load Pload_X_base.

[0041] For ease of understanding, let's take phase A as an example. The maximum load of phase A is Pmax_A. If the actual load of phase A, PloadA, is less than or equal to Pmax_A, then the base load of phase A, Pload_A_base, equals PloadA. If the actual load of phase A, PloadA, is greater than or equal to Pmax_A, then the base load of phase A, Pload_A_base, equals Pmax_A. Based on this logic, the base loads Pload_B_base and Pload_C_base of phases B and C can be calculated sequentially.

[0042] In this embodiment, after obtaining the base loads Pload_A_base, Pload_B_base, and Pload_C_base for phases A, B, and C, the total remaining load Premain and the total remaining load Premain_X for each phase can be calculated. The specific calculation formulas for the total remaining load Premain and the total remaining load Premain_X are as follows:

[0043] Premain=Pload-sum-(Pload_A_base+Pload_B_base+Pload_C_base).

[0044] Premain_X=Pmax_X-Pload_X_base.

[0045] It is important to know that, based on the calculated total remaining load Premain, if Premain≤0, it means that during the basic load allocation, the actual load PloadX of each phase did not exceed the maximum load Pmax of the corresponding phase. Therefore, there is no total remaining load that can be used for redistribution, that is, the remaining allocation amount Pload_X_else of each phase is 0. This makes the final load PpcsForLoad_X of each phase equal to the basic load Pload_X_base of each phase; where X={A, B, C}.

[0046] If Premain > 0, it means that during the basic load allocation, the actual load PloadX of some phases exceeded the maximum load Pmax of the corresponding phase. In this case, the total remaining load Premain of the system needs to be redistributed to obtain the final load PpcsForLoad_X of each phase. There are several ways to obtain the final load PpcsForLoad_X. For ease of understanding, two specific examples will be used to describe this in detail below.

[0047] Example 1: Based on the proportion of the total remaining load Premain_X for each phase, the total remaining load Premain is redistributed to obtain the remaining allocation amount Pload_X_else for each phase; the remaining allocation amount Pload_X_else for each phase is added to the corresponding base load Pload_X_base to obtain the final load PpcsForLoad_X for each phase. Where X = {A, B, C}; the calculation expressions for the remaining allocation amount Pload_X_else and the final load PpcsForLoad_X are as follows:

[0048] Pload_X_else= Premain×[Premain_X / (Premain_A+Premain_B+Premain_C)].

[0049] PpcsForLoad_X= Pload_X_base+Pload_X_else.

[0050] Example 2: The total remaining load Premain is redistributed based on the weighted ratio of the total remaining load Premain_X to the rated power Pn_X for each phase. The specific calculation process is as follows: The rated power Pn_X of each phase is calculated, and the rated power ratio Pn_X_ratio of each phase is obtained; the rated power ratio Pn_X_ratio of each phase is multiplied by the total remaining load Premain_X of the corresponding phase to obtain the rated power weight Pn_X_η of each phase; the total remaining load Premain is allocated based on the ratio of the rated power weight Pn_X_η of each phase to obtain the remaining allocation amount Pload_X_else of each phase; the remaining allocation amount Pload_X_else of each phase is added to the base load Pload_X_else to obtain the final load PpcsForLoad_X of each phase. Where X = {A, B, C}; the specific calculation formulas for the rated power ratio Pn_X_ratio and the remaining allocation amount Pload_X_else are as follows:

[0051] Pn_X_ratio=Pn_X / ΣPn_X.

[0052] Pload_X_else=Premain×[(Premain_X×Pn_X_ratio) / Σ(Premain_X×Pn_X_ratio)].

[0053] In this embodiment, after obtaining the final load PpcsForLoad_X for each phase, the total three-phase load PpcsForLoad_total can be calculated by adding them together: PpcsForLoad_A + PpcsForLoad_B + PpcsForLoad_C. Then, the average three-phase load is calculated based on the obtained total three-phase load PpcsForLoad_total, which is PpcsForLoad_total / 3. Based on the difference between the final load PpcsForLoad_X for each phase and the average three-phase load PpcsForLoad_total / 3, the unbalance of each phase, Unbalance_X, is calculated as: Unbalance_X = PpcsForLoad_X - PpcsForLoad_total / 3; where X = {A, B, C}.

[0054] It's important to understand that unbalance is used to characterize the deviation of the average load across each phase; the larger the deviation, the higher the three-phase unbalance of the system. After obtaining the unbalance_X for each phase, directly distributing it equally among the inverters might lead to compatibility issues; for example, inverters with lower rated power might not be able to handle large unbalance compensation amounts. Therefore, in this embodiment, a globally unified unbalance coefficient, i.e., a global unbalance coefficient, can be calculated based on the unbalance of each phase, thereby normalizing the system unbalance.

[0055] Specifically, the sum of the rated power of all inverters can be used as a benchmark to normalize the three-phase imbalance, resulting in the corresponding global imbalance coefficient ratio_unbalance_X; where X = {A, B, C}. That is, by dividing the imbalance Unbalance_X of each phase by the sum of the rated power ΣPn_i of all inverters (Pn_i represents the rated power of the i-th inverter), the corresponding global imbalance coefficient ratio_unbalance_X is obtained. The specific formula for calculating the global imbalance coefficient ratio_unbalance_X is: ratio_unbalance_X = Unbalance_X / ΣPn_i.

[0056] In this embodiment, for any i-th inverter, after obtaining the global unbalance coefficient ratio_unbalance_X for each phase, the three-phase unbalance adjustment command Unbalance_X_i required for local inverter power control, X={A, B, C}, can be calculated by multiplying the global unbalance coefficient ratio_unbalance_X by the inverter's rated power Pn_i. The specific calculation formula is: Unbalance_A_i=ratio_unbalance_X×Pn_i.

[0057] In this embodiment, as Figure 2 As shown, after obtaining the three-phase imbalance adjustment command Unbalance_X_i, the process of power regulation of the inverter through inverter power control is as follows: based on the generated three-phase imbalance adjustment command Unbalance_X_i, the three-phase equally distributed inverter power command PinvRef is superimposed to obtain each corresponding inverter power reference PinvRef_X in the control loop, X={A, B, C}; where the inverter power command PinvRef is equal to the total input power of the inverter.

[0058] Understandably, the object for obtaining the inverter power command PinvRef differs depending on the application scenario of the multi-inverter system. For example, in a photovoltaic power generation scenario, the inverter power command PinvRef equals the actual output power of the photovoltaic system; in a photovoltaic energy storage scenario, the inverter power command PinvRef equals the sum of the actual output power of the photovoltaic system and the actual output power of the energy storage unit.

[0059] Another aspect of this application provides an energy storage system for implementing the above-described three-phase imbalance regulation energy dispatch method; such as Figure 3 As shown, one preferred embodiment includes multiple energy storage inverters (INVs); the entire energy storage system adopts a master-slave control architecture, which allows one energy storage inverter (INV) to act as the master, and the other multiple energy storage inverters (INVs) to act as slaves. The master is responsible for global status monitoring, strategy calculation, and coordinated control; each slave is responsible for reporting the control and status information of its local device.

[0060] It is understandable that, such as Figure 4As shown, when implementing the aforementioned three-phase imbalance regulation energy dispatch method through an energy storage system, the tasks performed by the master unit include: acquiring the total three-phase load power of the system; determining the system's load-carrying strategy based on the total three-phase load power; allocating the basic load according to the determined load-carrying strategy; redistributing the total remaining load based on the maximum single-phase load capacity; calculating the final load of each phase based on the hierarchical load-carrying allocation of the total three-phase load power; calculating the three-phase imbalance degree based on the obtained final load; calculating the global imbalance coefficient based on the obtained three-phase imbalance degree; and finally broadcasting the calculated global imbalance coefficient to all slave units. Upon receiving the global imbalance coefficient, the slave units calculate the three-phase imbalance regulation command and adjust the inverter power according to the obtained three-phase imbalance regulation command, thereby efficiently reducing the three-phase imbalance of the entire energy storage system.

[0061] It should be understood that there are various types of energy storage systems based on actual application scenarios, including photovoltaic energy storage systems, wind energy storage systems, and hydropower energy storage systems. For ease of understanding, this embodiment will take a photovoltaic energy storage system as an example to describe in detail the specific architecture of the energy storage system and the three-phase imbalance adjustment process.

[0062] Specifically, such as Figure 2 As shown, each energy storage inverter INV, connected to a photovoltaic (PV) panel (PV) and a battery pack (BAT) at its input, and a three-phase load (LOAD) at its output, constitutes a single PV-energy storage parallel unit. The battery pack (BAT) can be a single pack or n packs connected in parallel; that is, battery packs BAT#1 to BAT#n are connected in parallel and then connected to the input of the energy storage inverter INV along with the PV panel. Multiple PV-energy storage parallel units can be labeled as PV-energy storage parallel units #1 to #N. Each PV-energy storage parallel unit is connected to the grid GRID via AC coupling, and the host information is determined through a higher-level designation or a competition mechanism. The battery packs of each PV-energy storage parallel unit are connected in parallel via communication cables, and the energy storage inverters INV are also connected in parallel via communication cables.

[0063] In this embodiment, for scenarios with high imbalance accuracy requirements, a feedback correction mechanism can be set up to perform closed-loop control of the overall system imbalance to ensure that the overall system imbalance meets the actual needs of the scenario. The specific mechanism is as follows: After each slave device executes its local three-phase imbalance adjustment command, it reports the actual adjustment effect to the master device; the master device summarizes the adjustment effects of all slave devices, and if the overall system imbalance does not meet the standard, the master device corrects the global imbalance coefficient based on the actual adjustment effect reported by the slave devices and reissues it to each slave device until the overall system imbalance meets the standard.

[0064] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A three-phase imbalance regulation energy dispatch method, applied to a multi-inverter system with a main control architecture, characterized in that, Includes the following steps: Obtain the actual load of each phase of the system and calculate the total three-phase load power; Compare the total three-phase load power with the rated total power; where the rated total power is equal to the sum of the rated power of the main inverter and the rated power of each slave inverter. When the total load power of the three phases is less than or equal to the rated total power, the first load distribution method is used to determine the final load of each phase. The specific process of the first load distribution method is as follows: determine the basic load of each phase according to the maximum bearing capacity of each phase; based on the basic load of each phase, calculate the total remaining load of the system and the total remaining bearing capacity of each phase, and distribute the total remaining load according to the total remaining bearing capacity of each phase to obtain the final load of each phase. When the total three-phase load power is greater than the rated total power, the second load distribution method is used to determine the final load of each phase. The specific process of the second load distribution method is as follows: based on the rated total power, calculate the average power of the three phases, and use the average power of the three phases as the final load of each phase. The three-phase unbalance is calculated based on the average load of the three phases and the final load of each phase. The three-phase unbalance is then normalized based on the sum of the rated power of all inverters to obtain the global unbalance coefficient of each phase. The master inverter transmits the global imbalance coefficient of each phase to each slave inverter, enabling each slave inverter to calculate the local three-phase imbalance regulation command for energy regulation by combining the global imbalance coefficient of each phase with its own rated power.

2. The three-phase imbalance regulation energy dispatch method as described in claim 1, characterized in that, Determining the load on the foundation includes the following process: If the actual load of a certain phase is less than or equal to the maximum load of the corresponding phase, the actual load of that phase shall be used as the base load. If the actual load of a certain phase is greater than the maximum load of the corresponding phase, the maximum load of that phase shall be taken as the base load.

3. The three-phase imbalance regulation energy dispatch method as described in claim 1, characterized in that, The final load calculation includes the following process: If the calculated total remaining load is less than or equal to zero, the final load of each phase is equal to the base load of each phase; If the calculated total remaining load is greater than zero, the total remaining load is allocated according to the proportion of the total remaining load of each phase to obtain the remaining allocation amount of each phase. The remaining load of each phase is added to the base load to obtain the final load of each phase.

4. The three-phase imbalance regulation energy dispatch method as described in claim 1, characterized in that, The final load calculation includes the following process: If the calculated total remaining load is less than or equal to zero, the final load of each phase is equal to the base load of each phase; If the calculated total residual load is greater than zero, calculate the rated power of each phase and obtain the percentage of rated power of each phase. The rated power weight of each phase is obtained by multiplying the rated power ratio of each phase by the total remaining load of the corresponding phase. The total remaining load is allocated based on the weight of the rated power of each phase to obtain the remaining allocation of each phase; the remaining allocation of each phase is added to the base load to obtain the final load of each phase.

5. The three-phase imbalance regulation energy dispatch method as described in claim 1, characterized in that, The unbalance of each phase is calculated based on the difference between the final load of each phase and the average load of the three phases. The global imbalance coefficient for each phase is obtained by dividing the imbalance of each phase by the sum of the rated power of all inverters.

6. The three-phase imbalance regulation energy dispatch method as described in claim 1, characterized in that, The three-phase global imbalance coefficients are multiplied by the inverter's rated power to obtain the three-phase imbalance regulation command required for energy regulation.

7. The three-phase imbalance regulation energy dispatch method according to any one of claims 1-6, characterized in that, During the power regulation process of the inverter, the inverter power reference for each corresponding phase in the control loop is obtained by superimposing the generated three-phase imbalance regulation command with the three-phase equally distributed inverter power command; wherein, the inverter power command is equal to the total input power of the inverter.

8. An energy storage system for implementing the three-phase imbalance regulation energy dispatch method according to any one of claims 1-7, characterized in that, It includes multiple energy storage inverters, one of which acts as the master and the other multiple energy storage inverters act as slaves; The host is used for global status monitoring and calculation of global imbalance coefficient, and the host is adapted to send the obtained global imbalance coefficient to all the slave machines; The slave device calculates the three-phase imbalance adjustment command based on the received global imbalance coefficient.

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