A load balancing control method and system for a photovoltaic energy storage charging station

Abstract

This invention discloses a load balancing control method and system for photovoltaic energy storage charging stations, comprising: determining the average load power, load deviation value, and station power deficit value based on the branch load power of each charging branch; determining the lifetime loss weight based on the state of charge, cluster temperature, cluster internal resistance, and cumulative flux of each energy storage cluster; determining the power allocation interval corresponding to each energy storage cluster based on the lifetime loss weight and instantaneous power adjustment margin, and forming a branch compensation sequence; subsequently performing power compensation on each charging branch in sequence to obtain the target power sharing result for each energy storage cluster corresponding to each charging branch; and finally, performing coordinated control on each energy storage cluster and each charging branch based on the target power sharing result. This invention can balance both the station load balance and the lifetime balance of energy storage clusters.

Description

Technical Field

[0001] This invention relates to the technical field of power scheduling and charge / discharge coordinated control of photovoltaic energy storage charging stations, and particularly to a load balancing control method and system for photovoltaic energy storage charging stations. Background Technology

[0002] With the increasing coordinated deployment of distributed photovoltaic power generation, energy storage converters, and high-power DC charging facilities, photovoltaic energy storage charging stations have gradually evolved from single energy access nodes into composite power electronic systems integrating photovoltaic absorption, energy storage regulation, and vehicle charging. Existing technologies typically focus on aspects such as power coordination within the station, DC bus stability control, energy storage state of charge management, peak shaving and valley filling of charging load, and grid-friendliness regulation. In existing solutions, the charging and discharging of the energy storage system is mainly based on the power difference between the photovoltaic output level and the charging demand to mitigate the impact of photovoltaic output fluctuations on the charging load; or multiple energy storage units are allocated and controlled based on the state of charge, rated capacity, or charge / discharge rate of the energy storage batteries to reduce the risks of local overcharging, over-discharging, and power exceeding limits; or station-level load forecasting, vehicle access timing, and electricity price factors are introduced into the scheduling process to optimize the overall output of the charging branch.

[0003] However, existing technologies still generally suffer from the following shortcomings: First, most solutions focus on station-level total power balancing. While this can adjust for insufficient photovoltaic output or sudden increases in charging load, it lacks fine-grained handling of load skew between charging branches, easily leading to long-term heavy loads and underutilization of some branches, resulting in uneven power distribution within the station. Second, when calling on energy storage systems for load compensation, existing solutions typically use state of charge or available capacity as the main allocation basis, failing to adequately consider differences in cluster temperature, internal resistance, and cumulative throughput between energy storage clusters. This causes power regulation tasks to be concentrated on a few energy storage clusters with better conditions, further leading to differentiation in the aging rate of energy storage clusters, inconsistent power boundary contraction, and increased subsequent maintenance costs. Third, although existing technologies introduce energy storage health or lifespan assessment factors, they remain at the station-level correction or total constraint level, lacking a power allocation upper limit reduction mechanism for individual energy storage clusters and a linkage control path that coordinates with the charging branch compensation sequence. Therefore, it is difficult to simultaneously address both load balancing and lifespan balancing constraints.

[0004] Therefore, if an orderly compensation rule can be formed for the load deviation of each charging branch, and the power allocation range of each energy storage cluster can be limited according to the lifespan loss state of each energy storage cluster, and the target power sharing result can be directly applied to the coordinated adjustment of the energy storage side and the charging branch side, it will be more conducive to improving the problem of uneven load distribution within the station and suppressing the problems of energy storage cluster call imbalance and aging differentiation.

[0005] In summary, existing photovoltaic energy storage charging station load regulation technologies suffer from problems such as coarse branch load distribution, insufficient consideration of differences in energy storage cluster lifespan, and low coordination between the energy storage side and the charging side. The invention of ours addresses the problem of the difficulty in simultaneously achieving load balance control and energy storage cluster lifespan balance in photovoltaic energy storage charging stations. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract and title of the invention. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0007] In view of the aforementioned existing problems, the present invention is proposed.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a load balancing control method for a photovoltaic energy storage charging station, comprising: determining an average load power based on the ratio of the sum of the branch load power of each charging branch to the number of charging branches; determining a load deviation value corresponding to each charging branch based on the difference between the branch load power of each charging branch and the average load power; determining a power deficit value within the station based on the difference between the sum of the branch load power of each charging branch and the photovoltaic output power; and determining a lifetime depreciation weight corresponding to each energy storage cluster based on the state of charge, cluster temperature, cluster internal resistance, and cumulative flux of each energy storage cluster. Based on the lifetime loss weight and instantaneous power adjustment margin corresponding to each energy storage cluster, the upper limit of power allocation for each energy storage cluster is reduced to obtain the power allocation range corresponding to each energy storage cluster; and the branch compensation order is formed according to the load deviation value corresponding to each charging branch from large to small. According to the branch compensation order, the corresponding charging branches are selected sequentially for power compensation. The power deficit value of the charging branch at the top is determined as the current total power compensation value, and the load deviation value of each of the other charging branches is determined as their respective current total power compensation value. Within the power allocation interval corresponding to each energy storage cluster, energy storage clusters are selected for power sharing in ascending order of lifetime loss weight to obtain the target power sharing result for each charging branch corresponding to each energy storage cluster. Based on the target power sharing results, the charging and discharging power of each energy storage cluster and the output power of each charging branch are controlled in a coordinated manner.

[0009] Secondly, the present invention provides a load balancing control system for a photovoltaic energy storage charging station, comprising: a load assessment module, configured to determine the average load power based on the ratio of the sum of the branch load power of each charging branch to the number of charging branches; determine the load deviation value corresponding to each charging branch based on the difference between the branch load power of each charging branch and the average load power; and determine the power deficit value within the station based on the difference between the sum of the branch load power of each charging branch and the photovoltaic output power. The lifetime assessment module is used to determine the lifetime loss weight of each energy storage cluster based on its state of charge, cluster temperature, internal resistance, and cumulative flux. The power constraint module is used to reduce the upper limit of power allocation for each energy storage cluster according to the lifetime loss weight and instantaneous power adjustment margin corresponding to each energy storage cluster, so as to obtain the power allocation interval corresponding to each energy storage cluster. The compensation scheduling module is used to form a branch compensation order according to the load deviation value corresponding to each charging branch from large to small, and to select the corresponding charging branches for power compensation in sequence according to the branch compensation order. The in-station power deficit value corresponding to the charging branch at the top is determined as the current total power compensation, and the load deviation value corresponding to each of the other charging branches is determined as their respective current total power compensation. Within the power allocation interval corresponding to each energy storage cluster, energy storage clusters are selected for power sharing according to the lifetime loss weight from small to large, so as to obtain the target power sharing result of each energy storage cluster for each charging branch. The collaborative control module is used to collaboratively control the charging and discharging power of each energy storage cluster and the output power of each charging branch based on the target power sharing result.

[0010] Thirdly, the present invention provides a computer device, comprising: One or more processors; The memory stores operable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, including the flow of the load balancing control method for a photovoltaic energy storage charging station as described above.

[0011] Fourthly, the present invention provides a computer-readable medium for storing software, the software including instructions executable by one or more computers, the instructions causing the one or more computers to perform operations, the operations including the flow of the load balancing control method for a photovoltaic energy storage charging station as described above.

[0012] The beneficial effects of this invention are as follows: By jointly determining the load deviation value of each charging branch, the power deficit value within the station, and the lifetime loss weight of each energy storage cluster, this invention obtains the load imbalance state within the station and the load-bearing state of the energy storage clusters, providing a clear basis for subsequent power allocation; by differentially reducing the upper limit of power allocation for each energy storage cluster and forming a branch compensation sequence, it suppresses the imbalance in energy storage cluster calls and the overload of local branches; by compensating the charging branches in sequence and distributing power according to the lifetime loss weight, it takes into account both load balance and lifetime balance; and by coordinating control between the energy storage side and the branch side, it improves the balance of power allocation within the station and the continuous adjustment capability of the energy storage system. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments 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. Wherein: Figure 1 This is a schematic flowchart of the load balancing control method for photovoltaic energy storage charging stations according to the present invention. Figure 2 This is a schematic diagram of the module distribution of the load balancing control system for photovoltaic energy storage charging stations shown in this invention. Detailed Implementation

[0014] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0015] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort should fall within the scope of protection of this invention.

[0016] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0017] According to an embodiment of the present invention, in combination Figure 1 The flowchart shown illustrates a load balancing control method for photovoltaic energy storage charging stations, which specifically includes the following steps: S1. Determine the average load power based on the ratio of the total branch load power of each charging branch to the number of charging branches; determine the load deviation value corresponding to each charging branch based on the difference between the branch load power of each charging branch and the average load power; determine the power deficit value within the station based on the difference between the total branch load power of each charging branch and the photovoltaic output power; determine the lifetime depreciation weight corresponding to each energy storage cluster based on the state of charge, cluster temperature, cluster internal resistance, and cumulative current flow of each energy storage cluster. Note that the following points should be noted in this step: In this embodiment, the charging branch is an independent power supply branch set up within the photovoltaic energy storage charging station corresponding to different charging terminal groups. Each charging branch is equipped with a branch voltage sampling unit and a branch current sampling unit. For any charging branch, at the same control moment, the branch voltage sampling value and the branch current sampling value of the charging branch are combined accordingly, and combined with the working state of the power conversion unit corresponding to the charging branch, the branch load power of the charging branch is determined. To avoid the interference of instantaneous fluctuations on subsequent sorting, in this embodiment, the branch load power in the three consecutive sampling periods before the same control moment is compared sequentially. When the fluctuation amplitude in the three sampling periods is less than 2% of the rated power of the charging branch, the branch load power corresponding to the latest sampling period is taken as the branch load power at the current control moment. When the fluctuation amplitude in any sampling period is greater than the rated power of the charging branch, the branch load power is determined as follows: When the branch load power is 2% of the rated power, the average branch load power over three consecutive sampling periods is taken as the branch load power at the current control moment. Then, the branch load power corresponding to all charging branches currently participating in load balancing control is accumulated one by one to obtain the sum of the branch load power of each charging branch. The number of charging branches currently in the conducting state and allowing power adjustment is determined as the number of charging branches. Then, based on the correspondence between the sum of branch load power and the number of charging branches, the average load power is obtained. After that, for each charging branch, the branch load power of the charging branch is compared with the average load power, and the difference between the two is the load deviation value corresponding to the charging branch. When the difference is positive, it indicates that the charging branch is higher than the current average load level in the station; when the difference is negative, it indicates that the charging branch is lower than the current average load level in the station.

[0018] In this embodiment, the photovoltaic output power is jointly determined by the DC power sampling unit configured on the photovoltaic array's combiner side and the AC power sampling unit configured on the grid-connected inverter side. Specifically, the output power of each combiner branch of the photovoltaic array is first summarized to obtain the DC-side summarized power, and then the three-phase power sampling values ​​on the output side of the grid-connected inverter unit are combined to obtain the AC-side output power. When the difference between the DC-side summarized power and the AC-side output power is less than or equal to 3% of the AC-side output power, the AC-side output power is determined as the photovoltaic output power; when the difference between the two is less than or equal to 3%, the AC-side output power is determined as the photovoltaic output power. When the value is greater than 3% of the AC output power, the smaller of the two values ​​is determined as the photovoltaic output power. This method is adopted because the smaller value can eliminate the amplified impact of short-time overshoot and sampling deviation on the power compensation judgment within the station. Then, the total branch load power is compared with the photovoltaic output power, and the difference between the two is the power deficit value within the station. When the total branch load power is greater than the photovoltaic output power, this positive difference is determined as the power deficit value within the station. When the total branch load power is less than or equal to the photovoltaic output power, the power deficit value within the station is determined to be 0 kW.

[0019] S1.1 For all energy storage clusters currently participating in load balancing control, determine their state of charge, cluster temperature, cluster internal resistance, and cumulative flux, and based on the state of charge, cluster temperature, cluster internal resistance, and cumulative flux of all energy storage clusters, determine their average state of charge, average cluster temperature, average cluster internal resistance, and average cumulative flux, which will serve as the cluster reference values ​​at the current control moment.

[0020] In this embodiment, the energy storage cluster is a battery cluster composed of multiple series-parallel connected battery modules and independently monitored by the cluster-level management unit. Each energy storage cluster has a unique energy storage cluster identifier; for example, the energy storage cluster identifier can be set as energy storage cluster 1, energy storage cluster 2, energy storage cluster 3, and energy storage cluster 4 in sequence.

[0021] For any energy storage cluster, the state of charge is determined by the cluster-level management unit corresponding to that energy storage cluster based on the cluster voltage, cluster current, and the changes in charge and discharge during a recent period of continuous operation. Specifically, the initial state of charge is first determined based on the open-circuit voltage range corresponding to the energy storage cluster in the resting phase, and then the initial state of charge is corrected by combining the cumulative changes in current during the continuous charge and discharge process before the current control time to obtain the state of charge at the current control time.

[0022] The cluster temperature is determined by multiple temperature sampling points located at different positions inside the energy storage cluster. Preferably, temperature sampling points can be set on the air inlet side, the central unit area, and the air outlet side of the energy storage cluster, and the sampling values ​​corresponding to each temperature sampling point are compared. When the difference between the maximum and minimum temperature values ​​is less than or equal to 3°C, the average value of the sampling values ​​of each temperature sampling point is determined as the cluster temperature of the energy storage cluster. When the difference between the maximum and minimum temperature values ​​is greater than 3°C, the maximum temperature value is determined as the cluster temperature of the energy storage cluster.

[0023] The cluster internal resistance is determined by the cluster-level management unit within the current change range of the energy storage cluster based on the correspondence between the voltage change and the current change. Preferably, within the change range of the energy storage cluster from steady-state charging to constant-current charging or from steady-state discharging to constant-current discharging, the cluster voltage change value and cluster current change value before and after the current transition are extracted, and the cluster internal resistance of the energy storage cluster is determined based on the corresponding ratio.

[0024] Furthermore, the cumulative throughput is determined based on the cumulative absolute value of the charging and discharging current of the energy storage cluster since its commissioning. It is continuously accumulated in the cluster-level management unit in chronological order, and the corresponding cumulative value is extracted at the current control moment as the cumulative throughput of the energy storage cluster.

[0025] After obtaining the state of charge, cluster temperature, cluster resistance, and cumulative flux for all energy storage clusters, the average state of charge is obtained by summing the states of charge of each cluster and dividing by the number of clusters. The average cluster temperature is obtained by summing the cluster temperatures of each cluster and dividing by the number of clusters. The average cluster resistance is obtained by summing the cluster resistance of each cluster and dividing by the number of clusters. The average cumulative flux is obtained by summing the cumulative flux of each cluster and dividing by the number of clusters. The average of these four values ​​is used as the cluster reference value at the current control time.

[0026] S1.2 For each energy storage cluster, the difference between the state of charge of the energy storage cluster and the average state of charge is taken as the state of charge deviation, the difference between the cluster temperature of the energy storage cluster and the average cluster temperature is taken as the cluster temperature deviation, the difference between the cluster internal resistance of the energy storage cluster and the average cluster internal resistance is taken as the cluster internal resistance deviation, and the difference between the cumulative flow rate of the energy storage cluster and the average cumulative flow rate is taken as the cumulative flow rate deviation. S1.3 For each energy storage cluster, the deviation of state of charge, cluster temperature, cluster internal resistance, and cumulative flux are scored according to a unified scoring rule. Specifically, a score of 1 is given when any deviation is less than or equal to 5% of the corresponding cluster reference value; a score of 2 is given when any deviation is greater than 5% but less than or equal to 10% of the corresponding cluster reference value; a score of 3 is given when any deviation is greater than 10% but less than or equal to 15% of the corresponding cluster reference value; and a score of 4 is given when any deviation is greater than 15% of the corresponding cluster reference value. The scores for state of charge, cluster temperature, cluster internal resistance, and cumulative flux for the same energy storage cluster are then summed to obtain the lifetime loss score for that energy storage cluster. S1.4 Arrange the lifetime loss scores of all energy storage clusters according to their numerical values, and determine the weight coefficient of each energy storage cluster according to a unified coefficient division rule; where the weight coefficient is 0.1 when the lifetime loss score is less than or equal to 4; 0.2 when the lifetime loss score is greater than 4 and less than or equal to 8; 0.3 when the lifetime loss score is greater than 8 and less than or equal to 12; and 0.4 when the lifetime loss score is greater than 12 and less than or equal to 16. Determine the lifetime loss weight corresponding to each energy storage cluster based on the ratio between the weight coefficient of each energy storage cluster and the sum of the weight coefficients of all energy storage clusters, and the sum of the lifetime loss weights of all energy storage clusters is 1.

[0027] It should be noted that, for any energy storage cluster, the weight coefficient corresponding to that cluster is ratioized to the sum of the weight coefficients. The result is the lifetime loss weight corresponding to that energy storage cluster. After adopting this method, the lifetime loss weights corresponding to all energy storage clusters constitute a normalized allocation result, and their sum is 1. For example, if the lifetime loss scores corresponding to four energy storage clusters are 4, 6, 10, and 12, respectively, then the corresponding weight coefficients are 0.1, 0.2, 0.3, and 0.3, respectively, and the sum of the weight coefficients is 0.9. Thus, the lifetime loss weights corresponding to the four energy storage clusters are 0.111, 0.222, 0.333, and 0.333, respectively. At this time, the energy storage cluster with a smaller lifetime loss weight indicates that its relative deviation is lower, and it can take priority in undertaking the compensation task in the subsequent power sharing process; the energy storage cluster with a larger lifetime loss weight indicates that its relative deviation is higher, and its power sharing will be subject to stricter constraints in the subsequent power sharing process.

[0028] Preferably, this embodiment first obtains the load deviation value and the power deficit value in the station, and then obtains the lifetime depreciation weight corresponding to each energy storage cluster. This allows the subsequent power sharing to address both the branch load imbalance problem and the current state of the energy storage cluster. As a result, it can reduce the additional burden on energy storage clusters in poor condition, reduce the trend of widening aging differences between energy storage clusters, and improve the stability and sustainability of the load balancing control process.

[0029] S2. Based on the lifetime loss weight and instantaneous power adjustment margin corresponding to each energy storage cluster, the upper limit of power allocation for each energy storage cluster is reduced to obtain the power allocation range corresponding to each energy storage cluster; the branch compensation order is formed according to the load deviation value corresponding to each charging branch from large to small. It should be noted that in this step: S2.1 Sort the load deviation values ​​corresponding to all charging branches in descending order of their numerical values ​​to obtain the initial compensation sequence; S2.2 For charging branches with the same load deviation value in the initial compensation sequence, they are rearranged according to the rated power of the branches from large to small to obtain the branch compensation order. S2.3 For each energy storage cluster, multiply the lifetime loss weight corresponding to the energy storage cluster with the instantaneous power adjustment margin corresponding to the energy storage cluster to obtain the power reduction value corresponding to the energy storage cluster. S2.4 For each energy storage cluster, subtract the corresponding power reduction value from the instantaneous power adjustment margin of the energy storage cluster to obtain the upper limit of power allocation for the energy storage cluster; when the subtraction result is less than 0, the upper limit of power allocation for the energy storage cluster is 0.

[0030] In a preferred embodiment, the instantaneous power adjustment margin is obtained as follows: For any energy storage cluster, the cluster-level management unit first provides the current allowable charge / discharge power boundary of the energy storage cluster, and then, in conjunction with the current charge / discharge power of the energy storage cluster, determines the power space that the energy storage cluster can continue to increase at the current control moment; specifically, when the energy storage cluster is in a discharge compensation state, the upper limit of the current allowable discharge power of the energy storage cluster is compared with the current actual discharge power of the energy storage cluster, and the difference between the two is determined as the instantaneous power adjustment margin of the energy storage cluster; when the energy storage cluster is in a charge absorption state, the upper limit of the current allowable charging power of the energy storage cluster is compared with the current actual charging power of the energy storage cluster, and the difference between the two is determined as the instantaneous power adjustment margin of the energy storage cluster.

[0031] The current allowable charge and discharge power boundary is not a single fixed value, but is jointly limited by the charge state range, cluster temperature range, continuous change state of cluster current, and rated power of the converter of the energy storage cluster. For example, when the rated discharge power of an energy storage cluster is 80 kW, the current actual discharge power is 35 kW, and the current allowable discharge power upper limit is determined to be 65 kW after considering its charge state, cluster temperature, and cluster internal resistance, then the instantaneous power regulation margin of the energy storage cluster is 30 kW.

[0032] S2.5. For each energy storage cluster, use 0 as the lower limit and the upper limit of the power allocation corresponding to the energy storage cluster as the upper limit to determine the power allocation range corresponding to the energy storage cluster.

[0033] S3. Power compensation is performed on the corresponding charging branches sequentially according to the branch compensation order. The power deficit value of the charging branch ranked first is determined as the current total power compensation, and the load deviation value of each of the remaining charging branches is determined as its respective current total power compensation. Within the power allocation range corresponding to each energy storage cluster, energy storage clusters are selected for power sharing in ascending order of lifetime loss weight, obtaining the target power sharing result for each charging branch corresponding to each energy storage cluster. It should be noted that in this step: S3.1 Select the charging branch that ranks first according to the branch compensation order as the current compensation branch, and determine the power deficit value in the station as the current power compensation total.

[0034] It should be noted that the power deficit value within the station represents the overall difference between the photovoltaic output and the total load demand of the branch at the current control moment. The charging branch with the highest deficit is the branch that needs the most priority adjustment. Therefore, the power deficit value within the station is used as the current total power compensation for the first charging branch, which ensures that the station-wide deficit compensation falls on the branch that needs the most attention first. When the power deficit value within the station is 0 kW, it indicates that the photovoltaic output has covered the total load demand of the current branch, and the current total power compensation for the first charging branch is also 0 kW. At this time, the additional compensation process undertaken by the energy storage cluster is no longer triggered. If the power deficit value within the station is positive, then this positive value is used as the current total power compensation for the first charging branch.

[0035] S3.2 Arrange all energy storage clusters in ascending order of lifetime loss weight to obtain the energy storage cluster sharing order, and determine the energy storage cluster with the highest ranking as the priority energy storage cluster to share the burden.

[0036] Specifically, among all energy storage clusters, the cluster with the lowest lifetime loss weight is selected as the first priority energy storage cluster for sharing the burden. If two or more energy storage clusters have the same lifetime loss weight, the upper limit of power allocation corresponding to these energy storage clusters is further compared, and the energy storage cluster with the larger upper limit of power allocation is ranked first. If the upper limit of power allocation is still the same, the cluster temperature corresponding to these energy storage clusters is compared, and the energy storage cluster with the lower temperature is ranked first. Through this step-by-step comparison method, when the lifetime loss weight is the same, the energy storage cluster that can bear more power and has a more stable thermal state can be further selected as the priority energy storage cluster for sharing the burden.

[0037] S3.3 For the current compensation branch, select the corresponding energy storage clusters in sequence according to the energy storage cluster sharing order, and determine the sharing power value within the power allocation range corresponding to the energy storage cluster; when the upper limit of the power allocation corresponding to the energy storage cluster is less than the current total power compensation, the upper limit of the power allocation corresponding to the energy storage cluster is determined as the sharing power value corresponding to the energy storage cluster; when the upper limit of the power allocation corresponding to the energy storage cluster is greater than or equal to the current total power compensation, the current total power compensation is determined as the sharing power value corresponding to the energy storage cluster. S3.4. Subtract the sharing power value from the current total power compensation to obtain the remaining compensation power. When the remaining compensation power is greater than 0, take the energy storage cluster identifier and the corresponding sharing power value that have participated in the power sharing as the current sharing result, and continue to select the next energy storage cluster for power sharing according to the energy storage cluster sharing order. When the remaining compensation power is equal to 0, associate all the energy storage cluster identifiers and the sharing power value corresponding to each energy storage cluster that participate in the power sharing of the current compensation branch to determine the target power sharing result corresponding to the current compensation branch.

[0038] The energy storage cluster identifier is a cluster-level number that uniquely identifies each energy storage cluster. Preferably, it can be set as energy storage cluster 1, energy storage cluster 2, energy storage cluster 3, and energy storage cluster 4 according to the access order of the energy storage clusters; it can also be formed by combining the energy storage cabinet number and the cluster number, for example, energy storage cabinet 1-energy storage cluster 1, energy storage cabinet 1-energy storage cluster 2, and energy storage cabinet 2-energy storage cluster 1.

[0039] S3.5 After the target power sharing result corresponding to the current compensation branch is determined, the charging branch located after the current compensation branch is selected as the next compensation branch according to the branch compensation order. The load deviation value corresponding to the next compensation branch is determined as the current total power compensation. The energy storage clusters are selected in sequence according to the energy storage cluster sharing order. The power sharing value corresponding to each energy storage cluster is determined within the power distribution range corresponding to each energy storage cluster until the target power sharing result corresponding to the next compensation branch is determined. S3.6. Determine the target power sharing results for the remaining charging branches in sequence according to the branch compensation order, and summarize the target power sharing results for each charging branch to obtain the target power sharing results for each charging branch corresponding to each energy storage cluster.

[0040] It should be noted that by first associating the first charging branch with the power deficit value within the station, and then associating subsequent charging branches with their respective load deviation values, and simultaneously selecting energy storage clusters for power sharing according to the lifetime loss weight from small to large, a unique and clear target power sharing result is obtained between each charging branch and each energy storage cluster. This enables the power compensation process to have a clear execution sequence and correspondence, facilitating the synchronous development of subsequent branch control and energy storage control, and reducing allocation ambiguity when multiple energy storage clusters share power in parallel.

[0041] S4. Based on the target power sharing results, coordinate the charging and discharging power of each energy storage cluster and the output power of each charging branch. It should be noted that in this step: S4.1. Accumulate all the power values ​​of the same charging branch to obtain the target output power of the charging branch; accumulate the power values ​​of all the charging branches of the same energy storage cluster to obtain the target charging and discharging power of the energy storage cluster. S4.2. Compare the target output power of each charging branch with the current output power of the corresponding charging branch; when the target output power of the charging branch is greater than the current output power of the charging branch, adjust the power of the charging branch by increasing it; when the target output power of the charging branch is less than the current output power of the charging branch, adjust the power of the charging branch by decreasing it; and compare the target charge / discharge power of each energy storage cluster with the current charge / discharge power of the corresponding energy storage cluster; when the target charge / discharge power of the energy storage cluster is greater than the current charge / discharge power of the energy storage cluster, adjust the power of the energy storage cluster by increasing it; when the target charge / discharge power of the energy storage cluster is less than the current charge / discharge power of the energy storage cluster, adjust the power of the energy storage cluster by decreasing it.

[0042] In a preferred embodiment, the power increase adjustment of the charging branch is specifically implemented as follows: when the target output power of a charging branch is greater than the current output power of the charging branch, the power difference of the charging branch is first determined, and then the power difference is decomposed into several consecutive power increase adjustment steps, and the output setting value of the converter unit corresponding to the charging branch is increased step by step in ascending order; preferably, when the power difference is less than or equal to 10 kW, the adjustment is completed in one step; when the power difference is greater than 10 kW, it is increased sequentially in increments of 5 kW until the target output power is reached; the power decrease adjustment of the charging branch is implemented in a corresponding manner, that is, when the target output power of a charging branch is less than the current output power of the charging branch, the power difference of the charging branch is first determined, and then the output setting value of the converter unit corresponding to the charging branch is decreased step by step in a consecutive power decrease adjustment step until the current output power of the charging branch drops to the target output power; the use of a graded adjustment method can reduce the bus fluctuation caused by sudden changes in branch power.

[0043] In a preferred embodiment, the power increase adjustment of an energy storage cluster is specifically implemented as follows: when the target charge / discharge power of an energy storage cluster is greater than the current charge / discharge power of that energy storage cluster, the power difference of that energy storage cluster is used as the adjustment basis, and power increase setting values ​​are sequentially issued to the bidirectional converter unit corresponding to that energy storage cluster, so that the output power or absorbed power of the energy storage cluster increases in a stepwise manner; preferably, between two consecutive sampling periods, the adjustment range does not exceed 10% of the rated charge / discharge power of the energy storage cluster each time; for the power decrease adjustment of an energy storage cluster, when the target charge / discharge power is less than the current charge / discharge power, the power setting value of the bidirectional converter unit corresponding to that energy storage cluster is gradually reduced in the same manner.

[0044] The above-mentioned charging branch adjustment and energy storage cluster adjustment are issued sequentially at the same control time, and the adjustment results are reviewed in the next sampling period. If a certain object has reached the corresponding target power in the next sampling period, the current setting value of the object is maintained. If the corresponding target power has not been reached, the next round of step adjustment is performed according to the remaining power difference.

[0045] S4.3. Compare the sum of the target charge / discharge power corresponding to each energy storage cluster with the sum of the target output power corresponding to each charging branch. When the sum of the target charge / discharge power corresponding to each energy storage cluster is greater than the sum of the target output power corresponding to each charging branch, reduce the target charge / discharge power corresponding to each energy storage cluster according to the lifetime loss weight from largest to smallest, and the corrected target charge / discharge power is greater than 0. When the sum of the target charge / discharge power corresponding to each energy storage cluster is less than the sum of the target output power corresponding to each charging branch, increase the target charge / discharge power corresponding to each energy storage cluster according to the lifetime loss weight from smallest to largest, and the corrected target charge / discharge power is less than the upper limit of the corresponding power allocation range. Continue until the sum of the target charge / discharge power corresponding to each energy storage cluster is consistent with the sum of the target output power corresponding to each charging branch.

[0046] The method for reducing power in this embodiment is as follows: First, select the energy storage cluster with the largest lifespan loss weight, and reduce the target charge / discharge power corresponding to the energy storage cluster downwards according to a fixed reduction step; preferably, the reduction amount each time can be 5% or 2 kW of the rated charge / discharge power of the energy storage cluster, and the smaller of the two values ​​is used as the single reduction amount; after completing the single reduction of the energy storage cluster, compare the corrected target charge / discharge power sum with the target output power sum again; if it is still greater than the target output power sum, continue to select the energy storage cluster with the second largest lifespan loss weight for the next reduction, and process in this order until the target charge / discharge power sum corresponding to each energy storage cluster is consistent with the target output power sum corresponding to each charging branch, or the difference is less than 1 kW; during the process, the corrected target charge / discharge power of any energy storage cluster is greater than 0 kW.

[0047] The incremental correction method in this embodiment is as follows: First, select the energy storage cluster with the smallest lifetime loss weight, and increase the target charge / discharge power corresponding to the energy storage cluster upwards in a fixed increment step; preferably, the increment for each adjustment can be 5% or 2 kW of the rated charge / discharge power of the energy storage cluster, and the smaller of the two values ​​is used as the single adjustment increment; after completing the single adjustment, compare the corrected target charge / discharge power sum with the target output power sum again; if it is still less than the target output power sum, continue to select the energy storage cluster with the second smallest lifetime loss weight for the next adjustment, and process in this order until the target charge / discharge power sum corresponding to each energy storage cluster is consistent with the target output power sum corresponding to each charging branch, or the difference is not greater than 1 kW; during the process, the corrected target charge / discharge power of any energy storage cluster is less than the upper limit of the power allocation range corresponding to that energy storage cluster.

[0048] Preferably, through this reduction correction and increment correction process, the target power sum on the energy storage cluster side can be kept consistent with the target power sum on the charging branch side, so that the branch side control quantity corresponds to the energy storage side control quantity.

[0049] It should be noted that, through the above steps, this embodiment first obtains the target output power corresponding to each charging branch and the target charging and discharging power corresponding to each energy storage cluster, then adjusts the power by increasing or decreasing it according to the comparison results, and finally makes the total power on the energy storage cluster side consistent with the total power on the charging branch side through reduction correction and increment correction, so that the entire load balancing control process forms a closed execution path, reduces the power distribution error within the station, improves the consistency of the output of each charging branch, and reduces the risk of the energy storage cluster exceeding the limit in the collaborative control process.

[0050] In the application of the above embodiments, refer to Figure 2 Other aspects disclosed in this invention also propose a load balancing control system for a photovoltaic energy storage charging station, comprising: a load assessment module, configured to determine the average load power based on the ratio of the sum of the branch load power of each charging branch to the number of charging branches; determine the load deviation value corresponding to each charging branch based on the difference between the branch load power of each charging branch and the average load power; and determine the power deficit value within the station based on the difference between the sum of the branch load power of each charging branch and the photovoltaic output power. The lifetime assessment module is used to determine the lifetime loss weight of each energy storage cluster based on its state of charge, cluster temperature, internal resistance, and cumulative flux. The power constraint module is used to reduce the upper limit of power allocation for each energy storage cluster according to the lifetime loss weight and instantaneous power adjustment margin of each energy storage cluster, so as to obtain the power allocation range corresponding to each energy storage cluster. The compensation scheduling module is used to form a branch compensation order according to the load deviation value corresponding to each charging branch from large to small, and to select the corresponding charging branches for power compensation in turn according to the branch compensation order. Among them, the in-station power deficit value corresponding to the charging branch with the first position is determined as the current power compensation total, and the load deviation value corresponding to each of the remaining charging branches is determined as their respective current power compensation total. Within the power allocation interval corresponding to each energy storage cluster, the energy storage clusters are selected for power sharing according to the lifetime loss weight from small to large, so as to obtain the target power sharing result of each energy storage cluster for each charging branch. The collaborative control module is used to collaboratively control the charging and discharging power of each energy storage cluster and the output power of each charging branch based on the target power sharing results.

[0051] Other aspects disclosed in the embodiments of the present invention also provide a computer device including one or more processors and a memory.

[0052] The memory is used to store operable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, including the flow of the load balancing control method for a photovoltaic energy storage charging station as described in the foregoing embodiments, particularly... Figure 1 The flowchart of the method is shown.

[0053] Other aspects disclosed in the embodiments of the present invention also propose a computer-readable medium for storing software including instructions executable by one or more computers, which, upon execution, cause the one or more computers to perform operations including the flow of the load balancing control method for a photovoltaic energy storage charging station described in the foregoing embodiments, particularly... Figure 1 The flowchart of the method is shown.

[0054] It should be recognized that embodiments of the present invention may be implemented or carried out by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable storage medium.

[0055] The method can be implemented using standard programming techniques, including a non-transitory computer-readable storage medium configured with a computer program in the computer program, wherein the storage medium is configured such that the computer operates in a specific and predefined manner.

[0056] Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system; however, if required, the program can be implemented in assembly or machine language.

[0057] In any case, the language can be either compiled or interpreted.

[0058] Furthermore, for this purpose, the program can run on programmed application-specific integrated circuits.

[0059] The processes described herein (or variations and / or combinations thereof) can be executed under the control of one or more computer systems configured with executable instructions, and can be implemented by hardware or a combination thereof as code (e.g., executable instructions, one or more computer programs, or one or more applications) that commonly executes on one or more processors. The computer program includes a plurality of instructions executable by one or more processors.

[0060] Furthermore, the method can be implemented in any suitable computing platform, including but not limited to personal computers, minicomputers, mainframes, workstations, networked or distributed computing environments, standalone or integrated computer platforms, or in communication with charged particle tools or other imaging devices.

[0061] Various aspects of the present invention can be implemented in machine-readable code stored on a non-transitory storage medium or device, whether portable or integrated into a computing platform, such as a hard disk, optical read and / or write storage medium, RAM, ROM, etc., such that it can be read by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the processes described herein.

[0062] Furthermore, machine-readable code, or parts thereof, can be transmitted via wired or wireless networks.

[0063] When such media includes instructions or programs that combine with a microprocessor or other data processor to implement the steps described above, the invention described herein includes these and other different types of non-transitory computer-readable storage media.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A load balancing control method for photovoltaic energy storage charging stations, characterized in that, include: The average load power is determined by the ratio of the total load power of all charging branches to the number of charging branches. Based on the difference between the branch load power of each charging branch and the average load power, the load deviation value corresponding to each charging branch is determined; based on the difference between the sum of the branch load power of each charging branch and the photovoltaic output power, the power deficit value in the station is determined; based on the state of charge, cluster temperature, cluster internal resistance and cumulative flow of each energy storage cluster, the lifetime depreciation weight corresponding to each energy storage cluster is determined. Based on the lifetime loss weight and instantaneous power adjustment margin corresponding to each energy storage cluster, the upper limit of power allocation for each energy storage cluster is reduced to obtain the power allocation range corresponding to each energy storage cluster; and the branch compensation order is formed according to the load deviation value corresponding to each charging branch from large to small. According to the branch compensation order, the corresponding charging branches are selected sequentially for power compensation. The power deficit value of the charging branch at the top is determined as the current total power compensation value, and the load deviation value of each of the other charging branches is determined as their respective current total power compensation value. Within the power allocation interval corresponding to each energy storage cluster, energy storage clusters are selected for power sharing in ascending order of lifetime loss weight to obtain the target power sharing result for each charging branch corresponding to each energy storage cluster. Based on the target power sharing results, the charging and discharging power of each energy storage cluster and the output power of each charging branch are controlled in a coordinated manner.

2. The load balancing control method for photovoltaic energy storage charging stations according to claim 1, characterized in that, The determination of the lifespan reduction weight includes: For all energy storage clusters currently participating in load balancing control, determine their state of charge, cluster temperature, cluster internal resistance, and cumulative flux. Based on the state of charge, cluster temperature, cluster internal resistance, and cumulative flux of all energy storage clusters, determine the average state of charge, average cluster temperature, average cluster internal resistance, and average cumulative flux, which will serve as the cluster reference values ​​at the current control moment. For each energy storage cluster, the difference between the state of charge of the energy storage cluster and the average state of charge is taken as the state of charge deviation, the difference between the cluster temperature of the energy storage cluster and the average cluster temperature is taken as the cluster temperature deviation, the difference between the cluster internal resistance of the energy storage cluster and the average cluster internal resistance is taken as the cluster internal resistance deviation, and the difference between the cumulative flow rate of the energy storage cluster and the average cumulative flow rate is taken as the cumulative flow rate deviation. For each energy storage cluster, the deviation of the state of charge, the deviation of the cluster temperature, the deviation of the cluster internal resistance, and the deviation of the cumulative flux are scored according to a unified scoring rule. Specifically, a score of 1 is given when any deviation is less than or equal to 5% of the corresponding cluster reference value; a score of 2 is given when any deviation is greater than 5% but less than or equal to 10% of the corresponding cluster reference value; a score of 3 is given when any deviation is greater than 10% but less than or equal to 15% of the corresponding cluster reference value; and a score of 4 is given when any deviation is greater than 15% of the corresponding cluster reference value. The scores for the same energy storage cluster—state of charge, cluster temperature, cluster internal resistance, and cumulative flux—are then summed to obtain the lifetime loss score for that energy storage cluster. The lifetime loss scores of all energy storage clusters are arranged according to their numerical values, and the weight coefficients of each energy storage cluster are determined according to a unified coefficient division rule. Specifically, when the lifetime loss score is less than or equal to 4, the weight coefficient is 0.1; when the lifetime loss score is greater than 4 and less than or equal to 8, the weight coefficient is 0.2; when the lifetime loss score is greater than 8 and less than or equal to 12, the weight coefficient is 0.3; and when the lifetime loss score is greater than 12 and less than or equal to 16, the weight coefficient is 0.

4. The lifetime loss weight corresponding to each energy storage cluster is determined based on the ratio between the weight coefficient of each energy storage cluster and the sum of the weight coefficients of all energy storage clusters, and the sum of the lifetime loss weights of all energy storage clusters is 1.

3. The load balancing control method for photovoltaic energy storage charging stations according to claim 1, characterized in that, The formation of the branch compensation sequence includes: The load deviation values ​​corresponding to all charging branches are sorted in descending order of numerical value to obtain the initial compensation sequence; For the charging branches with the same load deviation value in the initial compensation sequence, they are rearranged according to the rated power of the branches from large to small to obtain the branch compensation order.

4. The load balancing control method for photovoltaic energy storage charging stations according to claim 1, characterized in that, The power allocation range corresponding to each energy storage cluster is obtained, including: For each energy storage cluster, the lifetime loss weight corresponding to the energy storage cluster is multiplied by the instantaneous power adjustment margin corresponding to the energy storage cluster to obtain the power reduction value corresponding to the energy storage cluster. For each energy storage cluster, the power reduction value corresponding to the energy storage cluster is subtracted from the instantaneous power regulation margin corresponding to the energy storage cluster to obtain the power allocation upper limit corresponding to the energy storage cluster; when the subtraction result is less than 0, the power allocation upper limit corresponding to the energy storage cluster is 0. For each energy storage cluster, the power allocation range corresponding to that energy storage cluster is determined by using 0 as the lower limit and the upper limit of the power allocation corresponding to that energy storage cluster as the upper limit.

5. The load balancing control method for photovoltaic energy storage charging stations according to claim 1, characterized in that, The target power sharing result is obtained by: According to the branch compensation order, the charging branch that ranks first is selected as the current compensation branch, and the power deficit value in the station is determined as the current total power compensation. All energy storage clusters are arranged in ascending order of lifetime loss weight to obtain the energy storage cluster sharing order, and the energy storage clusters ranked first are determined as priority energy storage clusters; For the current compensation branch, the corresponding energy storage clusters are selected sequentially according to the energy storage cluster sharing order, and the sharing power value is determined within the power allocation interval corresponding to the energy storage cluster; when the upper limit of the power allocation corresponding to the energy storage cluster is less than the current total power compensation, the upper limit of the power allocation corresponding to the energy storage cluster is determined as the sharing power value corresponding to the energy storage cluster; when the upper limit of the power allocation corresponding to the energy storage cluster is greater than or equal to the current total power compensation, the current total power compensation is determined as the sharing power value corresponding to the energy storage cluster. The remaining compensation power is obtained by subtracting the sharing power value from the current total power compensation. When the remaining compensation power is greater than 0, the energy storage cluster identifiers and corresponding sharing power values ​​that have participated in power sharing are used as the current sharing result, and the next energy storage cluster is selected for power sharing according to the energy storage cluster sharing order. When the remaining compensation power is equal to 0, the identifiers of all energy storage clusters participating in the power sharing of the current compensation branch and the sharing power values ​​corresponding to each energy storage cluster are associated to determine the target power sharing result corresponding to the current compensation branch.

6. The load balancing control method for photovoltaic energy storage charging stations according to claim 5, characterized in that, Also includes: After the target power sharing result corresponding to the current compensation branch is determined, the charging branch located after the current compensation branch is selected as the next compensation branch according to the branch compensation order. The load deviation value corresponding to the next compensation branch is determined as the current total power compensation. Then, the energy storage clusters are selected sequentially according to the energy storage cluster sharing order. The power sharing value corresponding to each energy storage cluster is determined within the power allocation interval corresponding to each energy storage cluster until the target power sharing result corresponding to the next compensation branch is determined. The target power sharing results for the remaining charging branches are determined sequentially according to the branch compensation order. The target power sharing results for each charging branch are then summarized to obtain the target power sharing results for each charging branch corresponding to each energy storage cluster.

7. The load balancing control method for photovoltaic energy storage charging stations according to claim 1, characterized in that, The coordinated control includes: The target output power of a charging branch is obtained by summing up all the power values ​​of the same charging branch; the target charging and discharging power of an energy storage cluster is obtained by summing up all the power values ​​of the same charging branch. The target output power of each charging branch is compared with the current output power of the corresponding charging branch. When the target output power of the charging branch is greater than the current output power, the power of the charging branch is increased; when the target output power of the charging branch is less than the current output power, the power of the charging branch is decreased. Similarly, the target charge / discharge power of each energy storage cluster is compared with the current charge / discharge power of the corresponding energy storage cluster. When the target charge / discharge power of the energy storage cluster is greater than the current charge / discharge power, the power of the energy storage cluster is increased; when the target charge / discharge power of the energy storage cluster is less than the current charge / discharge power, the power of the energy storage cluster is decreased. The total target charge / discharge power corresponding to each energy storage cluster is compared with the total target output power corresponding to each charging branch. When the total target charge / discharge power corresponding to each energy storage cluster is greater than the total target output power corresponding to each charging branch, the target charge / discharge power corresponding to each energy storage cluster is reduced and corrected according to the lifetime loss weight from largest to smallest, and the corrected target charge / discharge power is greater than 0. When the total target charge / discharge power corresponding to each energy storage cluster is less than the total target output power corresponding to each charging branch, the target charge / discharge power corresponding to each energy storage cluster is increased and corrected according to the lifetime loss weight from smallest to largest, and the corrected target charge / discharge power is less than the upper limit of the corresponding power allocation range. This process continues until the total target charge / discharge power corresponding to each energy storage cluster is consistent with the total target output power corresponding to each charging branch.

8. A load balancing control system for a photovoltaic energy storage charging station, based on the load balancing control method for a photovoltaic energy storage charging station according to any one of claims 1 to 7, characterized in that, include: The load assessment module is used to determine the average load power based on the ratio of the total load power of each charging branch to the number of charging branches. The load deviation value corresponding to each charging branch is determined based on the difference between the branch load power of each charging branch and the average load power; the power deficit value in the station is determined based on the difference between the sum of the branch load power of each charging branch and the photovoltaic output power. The lifetime assessment module is used to determine the lifetime loss weight of each energy storage cluster based on its state of charge, cluster temperature, internal resistance, and cumulative flux. The power constraint module is used to reduce the upper limit of power allocation for each energy storage cluster according to the lifetime loss weight and instantaneous power adjustment margin corresponding to each energy storage cluster, so as to obtain the power allocation interval corresponding to each energy storage cluster. The compensation scheduling module is used to form a branch compensation order according to the load deviation value corresponding to each charging branch from large to small, and to select the corresponding charging branches for power compensation in sequence according to the branch compensation order. The in-station power deficit value corresponding to the charging branch at the top is determined as the current total power compensation, and the load deviation value corresponding to each of the other charging branches is determined as their respective current total power compensation. Within the power allocation interval corresponding to each energy storage cluster, energy storage clusters are selected for power sharing according to the lifetime loss weight from small to large, so as to obtain the target power sharing result of each energy storage cluster for each charging branch. The collaborative control module is used to collaboratively control the charging and discharging power of each energy storage cluster and the output power of each charging branch based on the target power sharing result.

9. A computer device, characterized in that, include: One or more processors; The memory stores operable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, including the flow of the load balancing control method for a photovoltaic energy storage charging station as described in any one of claims 1 to 7.

10. A computer-readable medium for storing software, characterized in that: The software includes instructions executable by one or more computers, which, upon execution, cause the one or more computers to perform operations including the flow of a load balancing control method for a photovoltaic energy storage charging station as described in any one of claims 1 to 7.

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