Power regulation method for energy storage system and energy storage system

Abstract

This application discloses a power regulation method and an energy storage system for an energy storage system. The power regulation method includes: determining the step feedback ratio corresponding to each effective energy storage converter; determining a target deficit value based on the total deficit power and total surplus power when the operating period is a charging period or a standby period; determining the target deficit value based on the total mutual assistance power and total deficit power when the operating period is a discharging period; executing a step adjustment step based on the target deficit value: performing differentiated adjustment on the power adjustment value that matches the adjustment direction and adapts to the equipment operating state based on the target deficit value and its represented adjustment direction, the net exchange power corresponding to each effective energy storage converter, and the equipment operating state represented by the step feedback ratio; determining the photovoltaic target power of each energy storage converter based on the minimum value among the sum of the load power, the maximum allowable charging power of the battery, and the power adjustment value, and the maximum photovoltaic power. Through the above method, the photovoltaic utilization rate can be effectively improved.

Description

TECHNICAL FIELD

[0001] The embodiments of the present application relate to the technical field of power regulation, in particular to a power regulation method of an energy storage system and the energy storage system. BACKGROUND

[0002] With the popularity of distributed photovoltaic and energy storage, multiple energy storage power conversion systems (PCSs) are often deployed in a household or commercial scenario, each of which is connected to a photovoltaic module and an energy storage battery and is connected to a power grid in parallel through an alternating current bus, and all the PCSs are centrally controlled by an energy management system (EMS).

[0003] At present, the traditional centralized EMS control scheme generally adopts an open-loop power distribution method, that is, the EMS directly issues a target output power instruction to each PCS mainly according to a photovoltaic power prediction result. This control method has the following defects: first, the control strategy has a high dependence on photovoltaic output prediction, and it is necessary to accurately obtain the maximum photovoltaic power prediction value of a single PCS, and environmental factors such as sudden weather changes and light fluctuations can easily cause prediction deviation, thereby causing inaccurate system power distribution; second, the overall pure open-loop control mechanism is adopted, and after the power instruction is issued, it is impossible to real-time correct the deviation according to the actual photovoltaic output and the system power gap, and the control precision is poor; third, the system uses a unified power control strategy throughout the process, and it is not optimized and adjusted differently for different operating conditions, and it is unable to adapt to the power grid interaction power constraint condition. The above defects can all cause the photovoltaic utilization rate of the system to be low, and it is difficult to fully exert the power generation benefits of the distributed photovoltaic. SUMMARY

[0004] The embodiments of the present application provide a power regulation method of an energy storage system and the energy storage system, which can effectively improve the photovoltaic utilization rate.

[0005] In a first aspect, the embodiments of the present application provide a power regulation method of an energy storage system. The energy storage system includes a plurality of energy storage converters. Any energy storage converter is electrically connected to a photovoltaic module and a battery, respectively. All energy storage converters are electrically connected to a power grid. The power regulation method includes: determining effective energy storage converters, wherein the effective energy storage converters are energy storage converters receiving a voltage output by the photovoltaic module greater than a preset voltage threshold; determining a step feedback ratio corresponding to each effective energy storage converter, wherein the step feedback ratio represents a tracking accuracy of a photovoltaic actual power corresponding to the effective energy storage converter to a photovoltaic target power in a current control period; determining a current operation period, wherein the operation period includes a charging period, a discharging period, and a standby period; when the operation period is the charging period or the standby period, determining a net exchange power corresponding to each energy storage converter according to a difference between the photovoltaic actual power corresponding to each energy storage converter in the current control period and a load power and a maximum allowable charging power of the battery; determining a total surplus power according to a sum of the net exchange powers greater than 0; determining a total deficiency power according to a sum of the net exchange powers less than 0; determining a target gap value according to a difference between the total deficiency power and the total surplus power, and performing a step regulation step according to the target gap value; when the operation period is the discharging period, determining the net exchange power corresponding to each energy storage converter according to a difference between the photovoltaic actual power corresponding to each energy storage converter in the current control period and the load power; determining the total surplus power according to a sum of the net exchange powers greater than 0; determining the total deficiency power according to a sum of the net exchange powers less than 0; sequentially distributing the total surplus power for grid feeding and battery charging, and calculating a total mutual aid power remaining after the distribution is completed; when the total mutual aid power is less than the total deficiency power, determining a target gap value according to a difference between the total deficiency power and the total mutual aid power, and performing the step regulation step according to the target gap value; wherein the step regulation step includes: performing a differential regulation of matching a regulation direction of a power adjustment value and adapting a device operation state of each effective energy storage converter according to the target gap value and the regulation direction represented by the target gap value, and the device operation state represented by the net exchange power and the step feedback ratio corresponding to each effective energy storage converter; determining the photovoltaic target power corresponding to each energy storage converter in the current control period according to a minimum value in the photovoltaic maximum power corresponding to each energy storage converter and a sum of the load power, the maximum allowable charging power of the battery, and the power adjustment value.

[0006] In a second aspect, the embodiments of the present application provide an energy storage system. The energy storage system includes: a plurality of energy storage converters, any of which is electrically connected to a photovoltaic module and a battery, respectively, and all of which are electrically connected to a power grid; and an energy management system electrically connected to each of the energy storage converters, including: at least one processor and a memory; the memory is coupled to the processor, and the memory is used to store instructions or programs, when the instructions or programs are executed by the at least one processor, the at least one processor executes the power regulation method of the energy storage system as in the first aspect.

[0007] The application provides a power regulation method of an energy storage system, wherein the energy storage system comprises a plurality of energy storage converters, any energy storage converter is respectively connected with a photovoltaic module and a battery, and all the energy storage converters are connected with a power grid. The power regulation method first performs threshold determination on the photovoltaic input voltage of each energy storage converter, screens out effective energy storage converters in an effective working state, introduces a step feedback ratio as a dynamic evaluation index for representing the tracking accuracy of the actual photovoltaic power to the target photovoltaic power, thereby constructing a closed-loop feedback mechanism, and overcoming the technical defects that the open-loop control cannot correct in real time. On this basis, the current operation period of the system is divided into a charging period, a discharging period and a standby period, and a differentiated power distribution strategy is adopted according to the power balance demand in different periods: in the charging or standby working condition, the net exchange power of each converter is calculated according to the actual photovoltaic power, the load power and the maximum allowable charging power of the battery, and then the target gap value is determined according to the difference between the total excess power and the total deficiency power; in the discharging working condition, the power grid feeding and the battery charging demand are preferentially met, and the target gap value is determined according to the difference between the remaining mutual aid power and the total deficiency power. No matter what operation period, the method executes differentiated step regulation on the power adjustment value based on the regulation direction indicated by the target gap value, in combination with the net exchange power of each effective energy storage converter and the real-time running state of the equipment reflected by the step feedback ratio, and finally determines the photovoltaic target power of each energy storage converter in the current control period by taking the sum of the load power, the maximum allowable charging power of the battery and the power adjustment value as a constraint, and cooperating with the photovoltaic maximum power limiting. Through the synergistic effect of the above-mentioned closed-loop feedback mechanism, the working condition self-adaptive partition control and the differentiated step regulation strategy, the application can effectively reduce the dependence on the photovoltaic power prediction accuracy, track the system power gap in real time and dynamically correct, effectively avoid the prediction deviation problem caused by light fluctuation, and thereby improve the system power control accuracy and the photovoltaic consumption utilization rate. BRIEF DESCRIPTION OF DRAWINGS

[0008] One or more embodiments are illustrated by way of example in the figures that are attached to this description, these illustrative examples not configuring a limitation to the embodiments, the elements with the same reference numerals in the figures representing similar elements.

[0009] Figure 1 is the flow of the power regulation method of the energy storage system provided by the embodiment of the application Figure 1 ; Figure 2 is the flow of the power regulation method of the energy storage system provided by the embodiment of the application Figure 2 ; Figure 3 is the flow of the power regulation method of the energy storage system provided by the embodiment of the application Figure 3 ; Figure 4is a flow of a power regulation method of an energy storage system provided by an embodiment of the present application Figure 4 ; Figure 5 is a flow of a power regulation method of an energy storage system provided by an embodiment of the present application Figure 5 ; Figure 6 is a flow of a power regulation method of an energy storage system provided by an embodiment of the present application Figure 6 ; Figure 7 is a flow of a power regulation method of an energy storage system provided by an embodiment of the present application Figure 7 ; Figure 8 is a schematic diagram of an energy management system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0010] For the purpose of clarity, technical solutions and advantages of the present application, the technical solutions of the present application will be described in detail below with reference to the drawings in the present application. Obviously, the embodiments in the present application are part of the embodiments, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0011] It should be noted that when an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements can be present therebetween.

[0012] In addition, the technical features involved in each of the embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0013] Please refer to Figure 1 , Figure 1 is a flow of a power regulation method of an energy storage system provided by an embodiment of the present application. The energy storage system includes a plurality of energy storage converters, any energy storage converter is electrically connected to a photovoltaic module and a battery, and all energy storage converters are electrically connected to a power grid. Specifically, the energy storage system is a direct current distributed and alternating current parallel architecture, each energy storage converter in the energy storage system has independent photovoltaic input and independent battery energy storage unit; the alternating current output side of all energy storage converters is connected in parallel to a common alternating current bus and connected to the power grid.

[0014] In a specific embodiment, the energy storage converter integrates an inverter inside the whole machine. The inverter is used to realize bidirectional conversion between direct current power and alternating current power. The inverter has a rated capacity. Any power transmitted through the alternating current side, including local alternating current load power, grid feeding power, grid charging power, and power exchange between energy storage converters, needs to pass through the inverter and occupy the rated capacity of the inverter. When the power generated by the photovoltaic module connected to the same energy storage converter is used to charge the battery connected to the energy storage converter, the charging process is completed in the direct current loop. The power is directly transmitted from the photovoltaic module to the battery through the direct current loop and does not pass through the alternating current-direct current conversion unit of the inverter. Therefore, the part of the direct current charging power does not occupy the capacity of the inverter. The self-direct current charging is only constrained by the maximum allowed charging power of the battery management system and is decoupled from the capacity of the inverter. The inverter can simultaneously and independently process the power exchange business on the alternating current side.

[0015] As shown in Figure 1 The power regulation method includes the following steps S110 to S170.

[0016] Step S110: Determine the effective energy storage converter, wherein the effective energy storage converter is an energy storage converter that receives a voltage output by a photovoltaic module greater than a preset voltage threshold.

[0017] The effective energy storage converter is an energy storage converter that has photovoltaic input and can participate in closed-loop step adjustment of photovoltaic output. The determination basis is to collect the direct current voltage output by the local photovoltaic module of the energy storage converter and compare the sampled voltage with the preset voltage threshold. If the output voltage of the photovoltaic module collected by the energy storage converter is greater than the preset voltage threshold, the energy storage converter is determined to be an effective energy storage converter. If the output voltage of the photovoltaic module collected by the energy storage converter is less than or equal to the preset voltage threshold, the energy storage converter is determined to be an ineffective energy storage converter. The preset voltage threshold is a preset direct current voltage threshold value used to determine whether the photovoltaic module is electrically connected to the energy storage converter. The energy storage converter determined to be effective will participate in subsequent step adjustment related to photovoltaic output. The power adjustment value of the energy storage converter determined to be ineffective is set to 0, but the energy storage converter still retains the ability of battery charging and discharging, equipment mutual assistance, and grid power exchange.

[0018] Step S120: Determine the step feedback ratio corresponding to each effective energy storage converter, wherein the step feedback ratio represents the tracking accuracy of the actual photovoltaic power of the effective energy storage converter corresponding to the target photovoltaic power in the current control period.

[0019] The step feedback ratio is a feedback quantity of closed-loop control.

[0020] The actual photovoltaic power of the effective energy storage converter in the current control period is the actual output power value of the photovoltaic module.

[0021] The photovoltaic target power refers to a photovoltaic output power instruction value expected to be reached by the effective energy storage converter in the current control period.

[0022] The tracking accuracy refers to the consistency between the actual execution result and the instruction target. The higher the tracking accuracy, the closer the actual output is to the target value; the lower the tracking accuracy, the farther the actual output deviates from the target value. The accuracy is quantitatively reflected by the numerical value of the step feedback ratio.

[0023] Specifically, the step is used to determine the step feedback ratio as the core feedback basis for the subsequent step adjustment step, so that the system can adaptively determine whether the photovoltaic target power needs to be adjusted.

[0024] It should be noted that in the embodiments of the present application, "corresponding" refers to a one-to-one mapping relationship; for example, the step feedback ratio corresponding to each effective energy storage converter means that each effective energy storage converter is respectively configured with an independent step feedback ratio.

[0025] In some embodiments, the specific implementation process of step S120 includes steps S210 to S230.

[0026] Step S210: When the photovoltaic target power corresponding to the bth effective energy storage converter is less than the photovoltaic maximum power corresponding to the bth effective energy storage converter, the step feedback ratio corresponding to the bth effective energy storage converter is the ratio of the photovoltaic actual power to the photovoltaic target power corresponding to the bth effective energy storage converter, wherein the bth effective energy storage converter is any effective energy storage converter.

[0027] Step S220: When the photovoltaic target power corresponding to the bth effective energy storage converter is 0, the step feedback ratio corresponding to the bth effective energy storage converter is configured as 1.

[0028] Step S230: When the photovoltaic target power corresponding to the bth effective energy storage converter is greater than or equal to the photovoltaic maximum power, and the photovoltaic actual power corresponding to the bth effective energy storage converter is equal to the photovoltaic target power, the step feedback ratio corresponding to the bth effective energy storage converter is configured to be greater than a preset lower threshold and less than a preset upper threshold.

[0029] Specifically, the photovoltaic target power corresponding to the bth effective energy storage converter is denoted as P PvTarget(b). The maximum PV power corresponding to the bth active energy storage converter is denoted as MaxPvPower(b), which represents the maximum theoretical output power value of the PV module connected to the bth active energy storage converter under the current illumination and temperature conditions, and is the physical upper limit of the PV module. The step feedback ratio corresponding to the bth active energy storage converter is denoted as η(b). The actual PV power corresponding to the bth active energy storage converter is denoted as P ActPv (b). The preset lower threshold is denoted as DownThrd, which represents the boundary value preset by the system for determining whether to lower. The preset upper threshold is denoted as UpThrd, which represents the boundary value preset by the system for determining whether to raise.

[0030] When P PvTarget (b) < MaxPvPower(b), η(b) = P ActPv (b) / P PvTarget (b). At this time, the upper limit of the PV hardware is not reached, and the tracking accuracy is directly represented by the actual output / power command. η(b) close to 1 represents that the actual power is close to the target, and the tracking effect is good, and the power can be tried to continue to be raised; η(b) much less than 1 represents that the actual power cannot reach the target due to insufficient illumination and the like, and the power adjustment value needs to be lowered in the future.

[0031] When P PvTarget (b) = 0, the bias is forced to be η(b) = 1 to avoid division by zero. The target power is 0, which means that the PV output is not required, and the ideal value 1 is assigned to the ratio to avoid entering the power reduction branch and causing algorithm abnormalities.

[0032] When P PvTarget (b) ≥ MaxPvPower(b), and P ActPv (b) = P PvTarget (b), DownThrd < η(b) < UpThrd is configured, such as η(b) = DownThrd + 0.01. Wherein, P PvTarget (b) ≥ MaxPvPower(b), and P ActPv (b) = P PvTarget (b) means that the PV target power of the bth active energy storage converter has reached or exceeded its maximum output capacity, and the actual output has indeed reached the target value, the device has reached the physical ceiling and cannot increase the output. At this time, η(b) is forced to be configured between DownThrd and UpThrd, so that the system does not trigger the raise or the lower in the subsequent step adjustment, thereby maintaining the current power stable.

[0033] Through steps S210 to S230, three determination methods of step feedback ratio are defined according to different working conditions of the effective energy storage converter. In the normal working condition of the photovoltaic target power being less than the photovoltaic maximum power, the ratio of the photovoltaic actual power to the photovoltaic target power is used to quantify the tracking accuracy; in the boundary working condition of the photovoltaic target power being zero, the step feedback ratio is forcibly configured as 1 to avoid division by zero error; in the physical saturation working condition of the photovoltaic target power reaching or exceeding the photovoltaic maximum power and the actual output being equal to the target value, the step feedback ratio is forcibly configured between the preset lower threshold and the preset upper threshold to guide the system to enter the adjustment and maintenance state. The three working conditions cover the full operation scene from normal tracking, boundary processing to physical saturation, ensuring that the step feedback ratio can effectively represent the device state in various situations.

[0034] Step S130: determining the current operation period, wherein the operation period includes a charging period, a discharging period and a standby period.

[0035] The charging period refers to an operation mode mainly characterized by absorbing electric energy; in this period, power is allowed to be taken from the power grid.

[0036] The discharging period refers to an operation mode mainly characterized by releasing electric energy; in this period, power is allowed to be fed to the power grid.

[0037] The standby period refers to an operation mode mainly characterized by zero power grid interaction; in this period, the system neither takes power from the power grid nor feeds power to the power grid.

[0038] Step S140: when the operation period is the charging period or the standby period, determining the net exchange power corresponding to each energy storage converter according to the difference between the photovoltaic actual power corresponding to each energy storage converter in the current control period and the load power and the maximum allowable charging power of the battery; determining the total excess power according to the sum of the net exchange power greater than 0; determining the total deficiency power according to the sum of the net exchange power less than 0; determining the target gap value according to the difference between the total deficiency power and the total excess power, and performing the step adjustment step according to the target gap value.

[0039] The load power corresponding to each energy storage converter refers to the electric power value required by the local load connected to each energy storage converter in the current control period. The maximum allowable charging power of the battery corresponding to each energy storage converter refers to the maximum charging power that can be safely absorbed by the battery connected to the energy storage converter in the current state given by the battery management system.

[0040] For the xth energy storage converter, the corresponding photovoltaic actual power is denoted as P ActPv (x), the load power is denoted as P Load (x), and the maximum allowable charging power of the battery is denoted as P BmsMax(x), the net exchange power is recorded as P net (x), wherein the xth energy storage converter is any energy storage converter in the energy storage system. Then P net (x)=P ActPv (x)-P Load (x)-P BmsMax (x)。P net (x)>0 means that the local photovoltaic still has surplus power after meeting the local load and the maximum charging of the local battery, and the energy storage converter is recorded as a surplus device; P net (x)<0 means that the local photovoltaic is insufficient to cover the local load and the charging demand of the battery, and there is a power gap, and the energy storage converter is recorded as a deficiency device; P net (x)=0 means that the local power balance, neither output nor need external power, and the energy storage converter is recorded as a balanced device.

[0041] The total surplus power P surplus is determined according to the following formula: The total deficiency power P deficit is determined according to the following formula: .

[0042] The target gap value is recorded as R1, and R1=P deficit -P surplus . Based on R1, the step adjustment step is performed, that is, step S160 is performed.

[0043] Step S150: When the running period is the discharge period, the net exchange power corresponding to each energy storage converter is determined according to the difference between the actual power of the photovoltaic and the load power corresponding to each energy storage converter in the current control period; the total surplus power is determined according to the sum of the net exchange power greater than 0; the total deficiency power is determined according to the sum of the net exchange power less than 0; the total mutual aid power remaining after the total surplus power is sequentially distributed for grid feeding and battery charging is calculated; when the total mutual aid power is less than the total deficiency power, the target gap value is determined according to the difference between the total deficiency power and the total mutual aid power, and the step adjustment step is performed according to the target gap value.

[0044] According to the foregoing, when the electrical energy generated by the photovoltaic module connected to the same energy storage converter is used to charge the battery connected to the energy storage converter itself, the direct current charging power generated does not occupy the capacity of the inverter. Based on this, in the discharge period, for the xth energy storage converter, P net (x)=P ActPv (x)-P Load (x)。

[0045] Grid feeding refers to delivering electric energy to the public grid. Battery charging refers to storing electric energy into local energy storage batteries. The total surplus power is sequentially allocated for grid feeding and battery charging, and the total mutual power remaining after the allocation is calculated, specifically, the total surplus power is allocated in the order: first for grid feeding, and then the remaining power is used for battery charging; after the two processes of grid feeding allocation and battery charging allocation, if there is still surplus, the surplus part is counted as the total mutual power. If the first two processes have consumed all the surplus power, the total mutual power is zero.

[0046] If the total mutual power is greater than or equal to the total deficiency power, the mutual aid is sufficient, and the step adjustment step does not need to be performed. If the total mutual power is less than the total deficiency power, there is a mutual aid interface (i.e. the target gap value R1), R1 = P deficit -P mutual_avail , where P mutual_avail is the total mutual power. The step adjustment step is performed based on R1, i.e. step S160 is performed.

[0047] , the step adjustment step is performed, i.e. step S160 is performed.

[0048] Step S160: According to the target gap value and the adjustment direction it represents, and the device operating state of each effective energy storage converter represented by the net exchange power and the step feedback ratio value corresponding to each effective energy storage converter, the power adjustment value is matched with the adjustment direction and adapted to the difference in device operating state.

[0049] , the target gap value can represent the overall power supply and demand state of the system. The positive and negative of the target gap value determines the direction of the step adjustment, specifically, a positive value indicates that the system is power deficient and needs to be adjusted positively; a negative value indicates that the system is power surplus and needs to be adjusted negatively; 0 indicates that the system is power balanced and does not need to be adjusted.

[0050] Matching the adjustment direction means that the increase or decrease operation of the power adjustment value performed is consistent with the adjustment direction indicated by the target gap value.

[0051] Adapting to the device operating state means that the specific adjustment amount performed or whether to perform adjustment needs to be matched with the operating state of each device.

[0052] Specifically, step S160 integrates the system global energy gap (target gap value and its adjustment direction) and the actual performance of each device (net exchange power and step feedback ratio) to accurately and differentially adjust the power adjustment value. In this way, the system not only ensures the correctness of the overall adjustment trend (matches the adjustment direction), but also takes into account the current real physical capability and tracking effect of each device (adapts to the device operating state). Through this differential adjustment, the system can accurately identify which devices have power generation potential and which devices have reached the limit, thereby effectively reducing the dependence on photovoltaic power prediction accuracy, tracking the system power gap in real time and dynamically correcting the deviation, effectively avoiding the prediction deviation problem caused by light fluctuation, and improving the system power control accuracy and photovoltaic utilization rate.

[0053] In some embodiments, as shown in FIG. 16, the specific implementation process of step S160 includes steps S310 to S340. Figure 2

[0054] Step S310: According to the state of charge value of the battery corresponding to each effective energy storage converter from low to high, each effective energy storage converter is set as the ith effective energy storage converter in turn.

[0055] The state of charge value of the battery corresponding to each effective energy storage converter refers to the remaining capacity percentage of the battery connected to each effective energy storage converter.

[0056] Specifically, all effective energy storage converters are arranged in order of their respective battery SOC values from low to high. When traversing the sorted sequence, the index i (i = 1, 2,..., Y, Y is the total number of effective energy storage converters) is used to refer to the device currently being processed, i.e., the first device processed is the device with the lowest SOC in the sequence, the second device processed is the device with the second lowest SOC, and so on, thereby ensuring that low-capacity batteries are processed first. In this way, the battery SOC balancing of each device can also be achieved simultaneously in the power dynamic allocation process.

[0057] Step S320: When the target gap value is less than 0, the power adjustment value corresponding to the ith effective energy storage converter is updated according to the maximum value of the first difference and 0, and the target gap value is updated according to the sum of the target gap value and the preset down step threshold value, wherein the first difference is the difference between the power adjustment value corresponding to the ith effective energy storage converter and the down step threshold value.

[0058] Specifically, the power adjustment value corresponding to the ith effective energy storage converter is denoted as P adj (i). The preset down step threshold value refers to the single step size preset by the system for negative adjustment, denoted as Δdown, which represents the amount of power adjustment reduced each time.

[0059] ​When R1 < 0, the first difference = P adj (i)-Δdown, according to P adj (i)=max(0,P) adj (i) - Δdown) yields the updated power adjustment value. The updated target gap value is obtained based on R1 = R1 + Δdown.

[0060] This step defines the adjustment operation when the target deficit value is less than 0 (power surplus). The power adjustment value of the current i-th effective energy storage converter is subtracted from the downward adjustment step threshold, and the result is compared with 0. The larger value is taken as the new power adjustment value (ensuring that it does not fall into a negative number); at the same time, the target deficit value is added to the downward adjustment step threshold to make it approach zero.

[0061] Step S330: When the target gap value is greater than 0, the power adjustment value is adjusted to adapt to the operating status of the equipment by using a lower step threshold or a preset upper step threshold, and the target gap value is updated according to the lower step threshold or the upper step threshold. When using an upper step threshold, the target gap value is updated according to the difference between the target gap value and the upper step threshold.

[0062] The preset upward adjustment step threshold refers to the single step size for positive adjustment that is pre-set by the system, denoted by Δup, which represents the amount of power adjustment increased each time.

[0063] Specifically, this step defines the adjustment operation when the target deficit value is greater than 0 (insufficient power). Based on the operating status of the i-th effective energy storage converter, it is determined whether to perform a positive step (increase) or a negative step (decrease) on its power adjustment value. At the same time, the target deficit value is updated synchronously according to the step direction adopted: when stepping positively, the target deficit value is reduced by the upward adjustment threshold; when stepping negatively, the target deficit value is added to the downward adjustment threshold, both approaching zero.

[0064] In one specific embodiment, such as Figure 3 As shown, the specific implementation process of step S330 includes the following steps S410 to S440.

[0065] S410: When the net switching power corresponding to the i-th effective energy storage converter is less than 0, update the power adjustment value corresponding to the i-th effective energy storage converter according to the maximum value between the first difference and 0, and update the target gap value according to the sum of the target gap value and the downward adjustment step threshold.

[0066] Specifically, P net (i) < 0 means that the local photovoltaic output is insufficient to cover the local consumption. Even if the entire system has a power deficit, if the local photovoltaic system itself lacks power, it is not suitable to further increase the photovoltaic target, and a downward step needs to be performed. In this case, the first difference = P adj(i) - Δdown, according to P adj (i) = max(0, P adj (i) - Δdown) to obtain an updated power adjustment value. According to R1 = R1 + Δdown, an updated target gap value is obtained.

[0067] When the net exchange power corresponding to the ith active energy storage converter is greater than or equal to 0, the following steps are performed: S420: If the step feedback ratio is greater than or equal to a preset upper limit threshold, the upper limit step threshold is updated according to the minimum value of the target gap value and the upper limit step threshold, the power adjustment value corresponding to the ith active energy storage converter is updated according to the minimum value of the first sum value and the maximum power value of the photovoltaic corresponding to the ith active energy storage converter, and the target gap value is updated according to the difference between the target gap value and the upper limit step threshold, wherein the first sum value is the sum of the power adjustment value corresponding to the ith active energy storage converter and the upper limit step threshold.

[0068] Specifically, P net (i) ≥ 0 and η(i) ≥ UpThrd means that the local power is surplus, and the actual output of the photovoltaic is well tracked, and has the potential to continue to increase the output of the photovoltaic. In this case, first, the updated upper limit step threshold is obtained according to Δup = min(R1, Δup); then, the first sum value P adj (i) + Δup is calculated; then, the updated power adjustment value corresponding to the ith active energy storage converter is obtained according to P adj (i) = min(P adj (i) + Δup, MaxPvPower(i)); finally, the updated target gap value is obtained according to R1 = R1 - Δup.

[0069] This step defines the adjustment operation when the step feedback ratio is greater than or equal to the preset upper limit threshold (high tracking accuracy) under the premise that the target gap value is greater than 0 and the device is a surplus or balanced device (the net exchange power is greater than or equal to 0). The device has high tracking accuracy and the ability to continue to increase the output, so the positive step is performed: the power adjustment value is added to the upper limit step threshold, and is constrained by the upper limit of the maximum power of the photovoltaic; at the same time, the target gap value is subtracted by the actual upper limit step threshold, and approaches zero.

[0070] It should be noted that in the embodiments of the present application, min() represents taking the minimum value, and max() represents taking the maximum value.

[0071] S430: If the step feedback ratio is less than the preset lower limit threshold, the power adjustment value corresponding to the ith active energy storage converter is updated according to the maximum value of the first difference value and 0, and the target gap value is updated according to the sum of the target gap value and the lower limit step threshold.

[0072] Specifically, P net (i) ≥ 0 and η(i) < DownThrd, means that the local is surplus in net power, but the step feedback ratio is very low; the actual photovoltaic output is far from the issued photovoltaic target power, which indicates that the illumination / hardware is limited, and it is not suitable to continue to increase the instruction, and it is necessary to reduce the power adjustment value. In this case, first, the first difference value P adj (i) - Δdown is calculated; then, according to P adj (i) = max(P adj (i) - Δdown, 0), the updated power adjustment value corresponding to the i-th effective energy storage converter is obtained; finally, according to R1 = R1 + Δdown, the updated target gap value is obtained.

[0073] This step defines the adjustment operation when the step feedback ratio is less than the preset lower limit threshold (low tracking accuracy) under the premise that the target gap value is greater than 0 and the device is a surplus or balanced device (net exchange power is greater than or equal to 0). The device is a surplus device, but its actual photovoltaic output is much lower than the target value, indicating that its output capacity is limited (such as light shading), and it does not have the condition to continue to increase the output, so the negative step is performed: the power adjustment value is reduced by the downward step threshold (but not less than 0); at the same time, the target gap value is added to the downward step threshold, and the gap is further expanded.

[0074] S440: If the step feedback ratio is greater than or equal to the preset lower limit threshold and less than the preset upper limit threshold, the power adjustment value is kept unchanged.

[0075] Specifically, P net (i) ≥ 0 and DownThrd ≤ η(i) < UpThrd, means that the step feedback ratio falls in the middle maintenance interval; it may be that the photovoltaic has reached the hardware saturation, or the tracking effect is general, and it is neither suitable to be lifted up nor to be lowered. In this case, P adj (i) remains unchanged; and the target gap value R1 does not change.

[0076] Step S340: When the target gap value is equal to 0, the power adjustment value corresponding to the i-th effective energy storage converter is kept unchanged.

[0077] This step defines the processing operation when the target gap value is equal to 0 (power balance). When the system power supply and demand has reached balance, there is no need to continue to adjust, and the power adjustment value of the current effective energy storage converter is kept unchanged.

[0078] Step S170: According to the sum of the load power, the maximum allowed charging power of the battery, and the power adjustment value, and the minimum value in the maximum power of the photovoltaic corresponding to each energy storage converter, the photovoltaic target power corresponding to each energy storage converter in the current control period is determined.

[0079] Specifically, the photovoltaic target power P PvTarget (i) is: PvTarget (i) = min(P Load (i) + P BmsMax (i) + P adj (i), MaxPvPower(i)).

[0080] This step sums the load power, the maximum allowed charging power of the battery and the power adjustment value of each energy storage converter to obtain the total expected power demand of the device, and compares the sum with the maximum photovoltaic power of the device to obtain the minimum value, so as to determine the photovoltaic target power of each energy storage converter in the current control period. The power adjustment value determined by the step-by-step adjustment in step S160 is superimposed on the rigid basic demand of the device in this step, so that the adjustment intention can be converted into specific photovoltaic output instructions: when the system needs to increase power, the power adjustment value is positive, the photovoltaic target power is correspondingly raised, and the device is driven to generate more photovoltaic power; when the system needs to reduce power, the power adjustment value is reduced, and the photovoltaic target power is correspondingly lowered, and the device is driven to generate less photovoltaic power. At the same time, by taking the minimum value of the photovoltaic target power and the maximum photovoltaic power, it is ensured that the target instruction issued does not exceed the physical output upper limit of the photovoltaic module in any case, so as to prevent the issuance of instructions exceeding the physical upper limit from the source. This step, as the final execution instruction generation link of the whole control process, accurately maps the global step-by-step adjustment result to the photovoltaic output target of each device, and completes the closed-loop connection from system-level decision to device-level execution.

[0081] In summary, the present application realizes the synergistic effect of the closed-loop feedback mechanism, the working condition self-adaptive partition control and the differentiated step-by-step adjustment strategy, thereby effectively reducing the dependence on the photovoltaic power prediction accuracy, tracking the system power gap in real time and dynamically correcting the deviation, effectively avoiding the prediction deviation problem caused by light fluctuation, and thus improving the system power control accuracy and the photovoltaic consumption utilization rate.

[0082] In some embodiments, the power adjustment method of the energy storage system further includes the following steps: when the operation period is a charging period or a standby period, if the i-th effective energy storage converter meets one of the following conditions one, condition two and condition three, the power adjustment value corresponding to the i-th effective energy storage converter remains unchanged; when the operation period is a discharging period, if the i-th effective energy storage converter meets one of the following conditions one, condition three and condition four, the power adjustment value corresponding to the i-th effective energy storage converter remains unchanged.

[0083] wherein the condition one is that the sum of the photovoltaic actual power and the power adjustment value corresponding to the i-th effective energy storage converter is greater than the maximum photovoltaic power. That is, P ActPv (i) + P adj(i) > MaxPvPower(i). Condition one specifically represents: the device photovoltaic output has approached / touched the upper limit of the native photovoltaic hardware output; even if the power adjustment value continues to increase, the photovoltaic output cannot be further improved, and the continued step adjustment is an invalid action. Therefore, the device is exited from the step adjustment, and the power adjustment value remains unchanged, avoiding invalid iterative operation. This condition is applicable to the charging, standby, and discharging periods.

[0084] Condition two is that the battery corresponding to the ith effective energy storage converter has been fully charged, and the mutual output power of the inverter in the ith effective energy storage converter is equal to the maximum power available for mutual aid. Among them, the battery has been fully charged, which means that the native battery SOC reaches the full charge threshold, and the BMS no longer allows the direct current side to continue to charge, P BmsMax (i) ≈ 0. The maximum power available for mutual aid = the rated power of the inverter - the native load power = P invmax (i) - P Load (i), then the mutual output power of the inverter in the ith effective energy storage converter is equal to the maximum power available for mutual aid, and the corresponding mutual output has occupied all the remaining AC capacity of the inverter except the local load. Condition two specifically represents: in the charging / standby period, the native battery has been fully charged, and the mutual output capacity of the inverter AC side has also reached the upper limit; the photovoltaic power locally has no place to consume, and continuing to increase the power adjustment value has no practical significance, so the step adjustment is exited, and the power adjustment value remains unchanged. This condition only takes effect in the charging and standby periods, and condition two is not used in the discharging period.

[0085] Condition three is that the ith effective energy storage converter has communication abnormalities or response timeouts. Specifically, it refers to the communication link between the ith effective energy storage converter and the EMS fails, such as data packet loss, frame error, check failure, etc., causing the EMS to be unable to normally receive the reported data of the device or issue instructions to it. Condition three specifically represents: the device data is not reliable, in order to prevent making incorrect step adjustments based on incorrect data, directly causing the device to exit the increase / decrease adjustment of the power adjustment value, maintaining the existing power adjustment value unchanged, avoiding control abnormalities and protecting system safety. This condition is applicable to the charging, standby, and discharging periods.

[0086] Condition four is that the battery corresponding to the ith effective energy storage converter has been fully charged, and the actual output power of the inverter in the ith effective energy storage converter is equal to its rated power. Among them, the actual output power of the inverter is equal to its rated power P invmax(i), indicating that the total output of the inverter AC side (local load + grid feed + mutual output) has reached the upper limit of the inverter hardware rating, and there is no excess AC power capacity. Condition four specifically represents: in the discharge scenario, the battery is fully charged, and the inverter AC output capacity has reached the upper limit; all destinations of photovoltaic output are fully saturated, and further increasing the power adjustment value cannot be absorbed by the system, which is invalid adjustment; the discharge period meets this condition, that is, the step adjustment is exited. This condition only applies to the discharge period.

[0087] In some embodiments, when the operation period is a charging period, the step adjustment step further includes: if the net exchange power corresponding to the i-th effective energy storage converter is greater than the rated power of the inverter in the i-th effective energy storage converter, setting the step feedback ratio to be less than the preset lower threshold.

[0088] Specifically, when the operation period is a charging period, the step adjustment step further includes special processing logic for inverter overload protection: when the net exchange power of the i-th effective energy storage converter is greater than its inverter rated power, it indicates that the device still has surplus power to be output externally through the inverter after meeting the local load and charging its own battery, but the mutual output demand has exceeded the upper limit of the physical capacity of the inverter. At this time, the system temporarily forces the step feedback ratio of the device to be set to a value lower than the preset lower threshold (such as DownThrd-0.01), so that it automatically enters the derating branch of step S430, and the step adjustment logic accordingly reduces its power adjustment value from cycle to cycle, thereby reducing the photovoltaic target power of the next cycle, and finally making the net exchange power fall within the rated capacity of the inverter.

[0089] This special processing does not need to add independent overload judgment and adjustment logic, but through the manipulation of the step feedback ratio, a unified signal, the overload protection is naturally integrated into the existing step adjustment framework, so that the device actively senses that it is in an overload risk and reduces the capacity. This design not only avoids overheating, damage or protective shutdown of the inverter due to long-term overrated power operation, but also maintains the unity and simplicity of the control logic, without the need to write additional adjustment branches for overload protection.

[0090] In some embodiments, as shown in Figure 4 When the operation period is a charging period, the step S160 of performing step adjustment according to the target gap value is performed, and the following steps S510 to S540 are further performed.

[0091] Step S510: According to the state of charge values of the batteries corresponding to all gap devices from low to high, the total surplus power is sequentially distributed to each gap device, and the mutual power corresponding to each gap device is determined, wherein the gap device is the energy storage converter with a net exchange power less than 0.

[0092] This step is the distribution of mutual aid power in the charging period. All short devices are sorted in order of the SOC value of the battery connected to each device from low to high, and then the total surplus power P surplus is distributed to each short device in this order, thereby determining the mutual aid power that each short device can obtain. Low SOC devices have priority in this distribution.

[0093] In a specific embodiment, the specific implementation process of distributing the total surplus power to each short device in order of the state of charge value of all short devices from low to high in step S510 includes the following steps S610 to step S660.

[0094] Step S610: Initialize the first remaining mutual aid power equal to the total surplus power.

[0095] Step S620: According to the order of the state of charge value of the battery corresponding to each short device from low to high, each short device is set as the jth short device in turn.

[0096] Step S630: Determine the mutual aid power corresponding to the jth short device according to the minimum value of the difference between the rated power and the load power of the inverter corresponding to the jth short device, the absolute value of the net exchange power and the first remaining mutual aid power.

[0097] Step S640: Update the first remaining mutual aid power according to the difference between the first remaining mutual aid power and the mutual aid power corresponding to the jth short device.

[0098] Step S650: Determine the remaining short power corresponding to the jth short device according to the difference between the absolute value of the net exchange power corresponding to the jth short device and the mutual aid power.

[0099] Step S660: Determine the remaining available capacity of the inverter in the jth short device according to the maximum value of the difference between the rated power and the load power of the inverter in the jth short device and the mutual aid power, and 0.

[0100] Specifically, (1) initialize the first remaining mutual aid power: R mutual1 =P surplus , where R mutual1 is the first remaining mutual aid power, and P surplus is the total surplus power calculated in step S140.

[0101] (2) Select the entire set of short devices. According to the ascending order of the battery SOC from low to high, take out the devices one by one in the order of sorting and mark them as the jth short device. The lower the SOC, the earlier the device is placed in the traversal sequence, and the mutual aid power is allocated preferentially to achieve battery SOC balancing.

[0102] (3) According to Pmutual1 (j)=min(P invmax (j)-P Load (j), |P net (j)|,Rmutual1), determine the mutual assistance power P corresponding to the j-th defective device. mutual1 (j). Among them, P invmax (j)-P Load (j) indicates the maximum amount of mutual charging power the inverter can receive after removing the local load; |P net (j)| represents the power shortfall of the device itself, that is, the total power that the device needs to make up; Rmutual1 represents the mutual aid resources that can be allocated at present. The minimum operation ensures that the allocation result simultaneously satisfies the capacity constraint, demand constraint, and total amount constraint.

[0103] (4) According to R mutual1 =R mutual1 -P mutual1 Update the first remaining mutual aid power. This means deducting the already allocated mutual aid power from the allocation pool to obtain the new first remaining mutual aid power; if R mutual1 =0 means that all mutual aid power has been allocated, and subsequent equipment with insufficient capacity will not be allocated mutual aid power.

[0104] (5) According to P RemainDeficit (j)=|P net (j)|-P mutual1 (j), determine the remaining deficit power P corresponding to the j-th deficit device. RemainDeficit (j). This represents the power gap that has not yet been filled by the deficient equipment after mutual power replenishment. If P RemainDeficit (j)=0 means that the mutual assistance has completely filled the gap in the equipment and there is no need to allocate grid charging.

[0105] (6) According to P Chg_invremain (j)=max(P invmax (j)-P Load (j)-P mutual1 (j), 0), determine the remaining available capacity P of the inverter in the j-th defective device. Chg_invremain (j). This represents the inverter's total charging capacity. First, the local load is deducted, then the allocated mutual charging power is deducted; only the remaining capacity can be used for grid charging. It is also necessary to prevent the calculation result from being negative.

[0106] The steps S620 to S660 are executed cyclically until the first remaining mutual aid power is equal to 0 or all the gap devices are traversed, and mutual aid power, remaining gap power, and inverter remaining available capacity of each gap device are output, which are used for the power grid power compensation power distribution step in step S520. The set of steps completely realizes multi-level constraint distribution of mutual aid power in the charging period, outputs intermediate state parameters required in the power grid power compensation link, realizes two-level distribution logic of "priority internal mutual aid, and then power grid power compensation", and simultaneously considers inverter hardware capacity constraint and battery state of charge balance target.

[0107] Step S520: If the target gap value is greater than 0, the power grid is used to compensate for each gap device to determine the power grid power compensation power corresponding to each gap device until the available power grid charging total power is 0 or all the gap devices have been distributed.

[0108] Wherein, the power grid power compensation power refers to the charging power value obtained by each gap device from the power grid, and the power grid power compensation power corresponding to the jth gap device is denoted as P GridAlloc (i) The available power grid charging total power refers to the total physical upper limit or remaining available amount of charging electric energy obtained by the energy storage system from the public power grid at the current moment, which cannot exceed the pre-set system maximum power grid charging power MaxGridChargePower.

[0109] Specifically, after step S160 realizes step adjustment, the target gap value is greater than 0, which represents that there is still a power gap after the internal mutual aid distribution, and the power grid needs to be compensated. The available power grid charging total power is distributed to each gap device in order until the power grid power is exhausted or the gap of all the gap devices is filled.

[0110] In a specific embodiment, the specific implementation process of compensating each gap device by the power grid in step S520 includes the following steps S710 to S730.

[0111] Step S710: Determine the power grid charging total power according to the minimum value between the target gap value and the pre-set maximum power grid charging power.

[0112] Step S720: Determine the power grid power compensation power corresponding to the jth gap device according to the minimum value among the remaining gap power of the jth gap device, the power grid charging total power, and the remaining available capacity of the inverter in the jth gap device.

[0113] Step S730: Update the power grid charging total power according to the difference between the power grid charging total power and the power grid power compensation power corresponding to the jth gap device.

[0114] Specifically, according to P GridChargeTotal =min(R1, MaxGridChargePower), the power grid charging total power PGridChargeTotal represents the grid supplemental power that the grid can output, which cannot exceed the system gap, and cannot exceed the grid charging upper limit set by the user.

[0115] According to P GridAlloc (j)=min(P RemainDeficit (j), P GridChargeTotal , P Chg_invremain (j)), the grid supplemental power P GridAlloc (j) corresponding to the jth gap device is determined. Wherein, P RemainDeficit (j) is the remaining gap power corresponding to the jth gap device, which is obtained by step S650; P Chg_invremain (j) is the remaining available capacity of the inverter in the jth gap device, which is obtained by step S660.

[0116] According to P GridChargeTotal =P GridChargeTotal -P GridAlloc (j), the updated grid charging total power is determined. represents that the grid supplemental power that has been allocated is deducted from the grid charging resource pool to be allocated; when P GridChargeTotal =0, the grid charging resource is exhausted, and the grid supplemental power allocation of subsequent devices is stopped.

[0117] Step S530: set the grid supplemental power corresponding to the energy storage converter other than the gap device to 0.

[0118] Specifically, the energy storage converter other than the gap device refers to the energy storage converter with P net (j)≥0, including the surplus device (energy storage converter with P net (j)>0) and the balanced device (energy storage converter with P net (j)=0). Set the grid supplemental power corresponding to the energy storage converter with P net (j)≥0 to 0, which means that only the device with power gap is allowed to accept grid charging; the device with surplus or balanced power is not allocated grid charging power.

[0119] Step S540: according to the difference between the sum of the mutual aid power and the grid supplemental power corresponding to each energy storage converter and the load power, determine the inverter target power corresponding to each energy storage converter in the current control period.

[0120] Specifically, according to P InvTarget (j)=P mutual1 (j)+P( GridAlloc (j)-P Load (j), the inverter target power P InvTarget (j) corresponding to the jth energy storage converter is determined.

[0121] For the gap device (Pnet (j) < 0): P mutual1 (j) is the received mutual assistance power, P GridAlloc (j) is the received grid complementary power; when the mutual assistance power and the grid complementary power are greater than the load power, P InvTarget (j) > 0, indicating that the inverter absorbs power from the AC side and performs charging; when the mutual assistance power and the grid complementary power are equal to the load power, P InvTarget (j) = 0, indicating that the inverter is on standby; when the mutual assistance power and the grid complementary power are less than the load power, P InvTarget (j) < 0, indicating that the inverter discharges to the load and the battery makes up the remaining load power.

[0122] For the surplus device (P net (j) > 0): P GridAlloc (j) = 0; P InvTarget (j) = -P mutual1 (j) - P Load (j). Where the surplus device outputs mutual assistance to the outside, so a negative sign needs to be added in front of P mutual1 (j). The final calculation of P InvTarget (j) is negative, indicating that the inverter discharges to the outside.

[0123] For the balanced device (P net (j) = 0): P mutual1 (j) = 0, P GridAlloc (j) = 0; P InvTarget (j) = -P Load (j), indicating that the inverter only outputs power to supply the local load, and a negative value represents discharging.

[0124] Through the allocation process, the charging period realizes the power allocation strategy of "photovoltaic surplus priority internal mutual assistance, and gap supplemented by the grid", ensuring the maximum utilization of photovoltaic and system power balance under the upper limit constraint of grid power in the charging period; at the same time, the mutual assistance and grid charging are sorted in low SOC priority, effectively promoting the SOC balance among the batteries.

[0125] In some embodiments, as Figure 5 shown, for the discharging period, the specific implementation process of the total surplus power in step S150 being allocated in turn for grid feeding and battery charging and the total mutual assistance power remaining after the allocation is completed includes the following steps S810 to step S840.

[0126] Step S810: Perform sequencing on the surplus devices: take the net exchange power from high to low as the first sequencing condition, and take the state of charge value of the battery from high to low as the second sequencing condition when the net exchange power is equal; according to the order after sequencing, each surplus device is set as the kth surplus device in turn, wherein the surplus device is the energy storage converter with the net exchange power greater than 0.

[0127] Specifically, this step includes two-level sequencing rules: First priority: the net exchange power from high to low; the device with greater surplus power is arranged in front, and preferentially participates in the grid feeding power distribution.

[0128] Second priority: when the net exchange power values of two or more devices are equal, the battery SOC is sequenced from high to low; the higher the SOC, the more preferentially the device participates in the feeding output, and the higher the SOC, the more preferentially the device outputs power in the discharging period, so as to realize the battery balancing.

[0129] Then, according to the order after sequencing, the devices are taken out one by one and recorded as the kth surplus device, and then enter the subsequent step for power distribution.

[0130] Step S820: When the total surplus power is greater than or equal to the preset maximum grid feeding power, the total surplus power is distributed for grid feeding to determine the feeding power corresponding to the kth surplus device, and if there is remaining power of the kth surplus device after the distribution is completed, the remaining power of the kth surplus device is used for charging the battery corresponding to the kth surplus device, and the remaining power after charging is the mutual aid power corresponding to the kth surplus device.

[0131] This step defines the distribution process when the total surplus power is sufficient (P surplus ≥ MaxGridDischargePower). In this branch, the total surplus power is preferentially used to meet the maximum feeding demand, and the distribution order is: first, the feeding power is distributed to each surplus device according to the sequencing of step S810, and the total feeding stops feeding distribution when the total feeding reaches the maximum grid feeding power; then each surplus device uses the remaining power to charge its own battery; if there is still remaining power after charging, the remaining power is used as mutual aid power for the deficient device.

[0132] In some embodiments, the specific implementation process of step S820 includes steps S910 to S950.

[0133] Step S910: Initialize the first feeding target power equal to the maximum grid feeding power.

[0134] Step S920: When the first power supply target power is greater than 0, determine the power supply power corresponding to the kth surplus device based on the minimum value among the difference between the rated power of the inverter and the load power corresponding to the kth surplus device, the net switching power, and the first power supply target power, and update the first power supply target power based on the difference between the first power supply target power and the power supply power corresponding to the kth surplus device.

[0135] Step S930: When the first power supply target power is less than or equal to 0, set the power supply corresponding to the kth surplus device to 0.

[0136] Specifically, initialize the first feed target power P G1 :P G1 =P MaxGridDischarge This indicates that the first target power variable for power supply is assigned the maximum grid power supply, which serves as the starting remaining power supply quota for subsequent allocation operations.

[0137] In P G1 When >0, it is determined that there is still an allocable grid feed quota, according to P. grid (k)=min(P invmax (k)-P Load (k), P net (k), P G1 Determine the feed power P corresponding to the k-th surplus device. grid (k). And according to P G1 =P G1 -P grid (k) determines the updated first feed target power.

[0138] In P G1 When P ≤ 0 grid (k)=0 indicates that the grid power supply quota has been fully allocated, and no further grid power supply will be allocated to the surplus equipment.

[0139] Step S940: Determine the remaining power corresponding to the k-th surplus device based on the difference between the net switching power and the feed power corresponding to the k-th surplus device.

[0140] Specifically, according to P remain_after_feed (k)=P net (k)-P grid (k), determine the remaining power corresponding to the k-th surplus device. This remaining power P remain_after_feed (k) represents the remaining power of the k-th surplus device that can be used for charging its own battery and for external power output.

[0141] Step S950: When the remaining power corresponding to the kth surplus device is greater than 0, the charging power of the battery corresponding to the kth surplus device is determined according to the minimum value of the remaining power corresponding to the kth surplus device and the maximum allowed charging power of the battery, and the mutual aid power corresponding to the kth surplus device is determined according to the difference between the remaining power corresponding to the kth surplus device and the charging power of the battery corresponding to the kth surplus device.

[0142] Specifically, in the P remain_after_feed (k) > 0, the kth surplus device charges its own battery with its own remaining power (DC side, without passing through the inverter), and the charging power of the battery corresponding to the kth surplus device is determined according to P charge (k) = min(P remain_after_feed (k), P BmsMax (k)).

[0143] After the charging power is allocated, the mutual aid power corresponding to the kth surplus device is determined according to P remain_after_charge (k) = P remain_after_feed (k) - P charge (k).

[0144] The above process realizes the step-by-step consumption and total conservation of the feed-in allowance through the chain structure of "initializing the feed-in allocation, calculating the charging and mutual aid, and determining the charging and mutual aid"; ensures the physical execution of the feed-in allocation through the triple minimum constraint; and strictly follows the power direction sequence of "feed-in -> photovoltaic DC charging (i.e., self-charging) -> mutual aid" to strictly follow the three-level priority of the discharging period, thereby ensuring the optimal use of the photovoltaic surplus power under the maximum feed-in power constraint.

[0145] Step S830: When the total surplus power is less than the maximum grid feed-in power, the total surplus power is used for grid feed-in to determine the photovoltaic feed-in power corresponding to the kth surplus device, the remaining feed-in gap is determined according to the difference between the maximum grid feed-in power and the total surplus power, and the remaining feed-in gap is supplemented by discharging the battery corresponding to the dischargeable device to determine the feed-in power corresponding to the kth surplus device until the remaining feed-in gap is 0 or all dischargeable devices have been allocated, wherein the mutual aid power corresponding to the kth surplus device is 0, and the dischargeable device is an energy storage converter that allows the battery to discharge.

[0146] This step defines the allocation process when the total surplus power is insufficient (P surplus < MaxGridDischargePower). In this branch, all photovoltaic surpluses are used for feed-in, and the insufficient part is supplemented by discharging the battery of the dischargeable device. Since all photovoltaic surpluses have been used for feed-in, the mutual aid power of each surplus device is zero.

[0147] In some embodiments, the implementation process of step S830 includes steps S1010-S1040.

[0148] Step S1010: initialize the second feeding target power equal to the total surplus power.

[0149] Step S1020: when the second feeding target power is greater than 0, determine the photovoltaic feeding power corresponding to the kth surplus device according to the minimum value among the difference between the inverter rated power and the load power corresponding to the kth surplus device, the net exchange power and the second feeding target power, and update the second feeding target power according to the difference between the second feeding target power and the photovoltaic feeding power corresponding to the kth surplus device.

[0150] Step S1030: when the second feeding target power is equal to 0, determine the remaining feeding gap power according to the difference between the maximum grid feeding power and the total surplus power.

[0151] Step S1040: determine the inverter remaining available capacity corresponding to the kth surplus device according to the maximum value among the difference between the inverter rated capacity and the feeding power and the load power corresponding to the kth surplus device and 0; determine the battery discharge power corresponding to the kth surplus device according to the minimum value among the remaining feeding gap power, the maximum allowed battery discharge power corresponding to the kth surplus device and the inverter remaining available capacity; determine the feeding power corresponding to the kth surplus device according to the sum of the photovoltaic feeding power and the battery discharge power corresponding to the kth surplus device, and update the remaining feeding gap power according to the difference between the remaining feeding gap power and the battery discharge power corresponding to the kth surplus device.

[0152] Specifically, initialize the second feeding target power P G2 G2 =P surplus . It means that the second feeding target power variable is assigned to the total surplus power as the starting surplus feeding quota for the subsequent allocation operation.

[0153] When P G2 > 0, it is determined that there is still unallocated photovoltaic surplus feeding quota, and P grid_pv (k) = min(P invmax (k) - P Load (k), P net (k), P G2 ), the photovoltaic feeding power P grid_pv (k) corresponding to the kth surplus device is determined. And P G2 =P G2 - P grid_pv (k) is determined to update the second feeding target power.

[0154] When P G2 ​=0, it is determined that the photovoltaic surplus power has been fully allocated for grid feeding. At this time, according to R batt =MaxGridDischargePower-P surplus , the remaining feeding gap power R batt is determined. The remaining feeding gap power R batt is the feeding gap that still needs to be supplemented by battery discharge; if R batt ≤0 is calculated, the gap is 0, and no battery discharge is needed.

[0155] According to P invremain (k)=max(0, P invmax (k)-P grid_pv (k)-P Load (k)), the remaining available capacity P invremain (k) of the inverter corresponding to the kth surplus device is determined.

[0156] According to P batt_discharge (k)=min(R batt , P BmsDischargeMax (k), P invremain (k)), the battery discharge power P batt_discharge (k) corresponding to the kth surplus device is determined. Wherein, P BmsDischargeMax (k) is the maximum allowed discharge power of the battery, which is the maximum discharge power that the battery connected to the device can safely output in the current state given by the battery management system.

[0157] The battery discharge power corresponding to the kth surplus device is added to the feeding instruction of the device, and the feeding power P grid (k) corresponding to the kth surplus device is obtained: P grid (k)=P grid_pv (k)+P batt_discharge (k).

[0158] According to R batt =R batt -Pbatt_discharge(k), the updated remaining feeding gap power is determined.

[0159] The above process ensures that the battery discharge allocation is physically executable through the triple minimum constraint, realizes the feeding strategy of "photovoltaic priority and battery gap filling" through the three-stage structure of "photovoltaic feeding allocation→gap calculation→battery discharge supplement" when the total surplus power is insufficient, and promotes battery balancing through the SOC of the dischargeable device from high to low.

[0160] It can be understood that after steps S1010 to S1040 are executed, all photovoltaic surpluses have been fully used for feeding, and there is no remaining power, so the total mutual aid power P mutual_availThe value is 0. In this case, the equipment in short supply cannot receive mutual assistance and needs to draw power from the grid or make up the gap through step-by-step regulation.

[0161] Step S840: Determine the total mutual assistance power based on the sum of the mutual assistance power of each surplus device with a mutual assistance power greater than 0.

[0162] Specifically, the mutual assistance power of the kth surplus device is P. remain_after_charge (k), then the total mutual assistance power P mutual_avail for: Where T represents the surplus equipment with mutual assistance power greater than 0.

[0163] Thus, during the discharge period, a three-tiered allocation sequence is achieved: "power supply priority, photovoltaic DC charging second, and mutual assistance last." This prioritizes power supply to the grid to generate revenue, followed by using surplus power to charge the batteries and improve energy storage levels, with the remaining power used for mutual assistance output. Simultaneously, the first prioritization condition ensures that the equipment with the largest surplus power undertakes the power supply task, while the second prioritization condition further prioritizes high-SOC equipment among high-net-power exchange equipment. This promotes overall battery SOC balance, maximizing photovoltaic utilization and achieving battery SOC balance under the constraint of maximum power supply during the discharge period.

[0164] In some embodiments, such as Figure 6 As shown, during the operation period when it is the discharge period, after performing step S160 to calculate the remaining total mutual assistance power after the allocation is completed, the following steps S1110 to S1140 are also performed.

[0165] Step S1110: Determine the corresponding mutual assistance output power of each surplus device based on the total mutual assistance power.

[0166] This step determines the mutual aid output power to be undertaken by each surplus device based on the total mutual aid power, and this power will be transmitted to the deficit device via the AC bus.

[0167] In a specific embodiment, the specific implementation process of step S1110 includes the following steps: determining the mutual assistance output power corresponding to the k-th surplus device based on the minimum value among the difference between the rated power of the inverter corresponding to the k-th surplus device, the load power, and the feed power, and the mutual assistance power corresponding to the k-th surplus device.

[0168] Specifically, according to P mutual_out (k)=min(P remain_after_charge (k), P invmax (k)-P Load (k)-P grid (k)), determine the mutual aid output power P corresponding to the kth surplus device. mutual_out (k). Wherein, P invmax(k) - P Load (k) - P grid (k) the upper limit of the power that the AC side of the inverter can be used for internal mutual assistance output after deducting the local load and grid feed-in.

[0169] Step S1120: determining the second remaining mutual assistance power according to the minimum value between the total mutual assistance power and the total deficiency power.

[0170] Specifically, the second remaining mutual assistance power is determined according to R mutual2 = min (P mutual_avail , P deficit ).

[0171] This step is a total amount constraint link of the mutual assistance power in the discharging period. The minimum value between the total mutual assistance power and the total deficiency power is obtained, and the total amount of the mutual assistance power that can be actually distributed to the deficiency devices (the second remaining mutual assistance power) is obtained, so as to ensure that the distributed mutual assistance power does not exceed the available supply amount and does not exceed the total demand amount of the system.

[0172] Step S1130: distributing the second remaining mutual assistance power to all the deficiency devices to determine the mutual assistance input power corresponding to each deficiency device until the second remaining mutual assistance power is 0 or all the deficiency devices have been distributed.

[0173] Specifically, the mutual assistance power is distributed to each deficiency device in turn, so that the mutual assistance input power corresponding to the kth deficiency device can be obtained. This step is an input end distribution link of the mutual assistance power in the discharging period. The second remaining mutual assistance power is distributed to all the deficiency devices (in the priority order from low to high SOC), and the mutual assistance input power actually obtained by each deficiency device is determined until the mutual assistance power is exhausted or the deficiency of all the deficiency devices is filled up.

[0174] In a specific embodiment, the specific implementation process of step S1130 includes the following steps S1210 to step S1230.

[0175] Step S1210: sequentially setting each deficiency device as the mth deficiency device according to the order from low to high of the state of charge values of the batteries corresponding to the deficiency devices.

[0176] Step S1220: determining the mutual assistance input power corresponding to the mth deficiency device according to the minimum value between the difference between the rated power of the inverter corresponding to the mth deficiency device and the load power, the absolute value of the net exchange power, and the second remaining mutual assistance power and the maximum allowed charging power of the battery.

[0177] Step S1230: updating the second remaining mutual assistance power according to the difference between the second remaining mutual assistance power and the mutual assistance input power corresponding to the mth deficiency device.

[0178] Specifically, the batteries corresponding to each deficient device are sorted in ascending order of SOC, and each deficient device is designated as the m-th deficient device. This ensures that the deficient device with the lowest SOC receives mutual power first, thereby promoting SOC balance among the batteries.

[0179] According to P mutual_in (m)=min(|P net (i)|,R mutual2 P BmsMax (m), P invmax (m)-P Load (m)), determine the mutual assistance input power P corresponding to the m-th defective device. mutual_in (m).

[0180] According to R mutual2 =R mutual2 -P mutual_in (m), determine the updated second residual mutual aid power R mutual2 .

[0181] Step S1140: Determine the inverter target power corresponding to each energy storage converter in the current control cycle based on the difference between the mutual input power and mutual output power, the feed power and the load power corresponding to each energy storage converter.

[0182] Specifically, according to P InvTarget (m)=P mutual_in (m)-P Load (m)-P grid (m)-P mutual_out (m), determine the target inverter power corresponding to the m-th energy storage converter.

[0183] For surplus equipment: P mutual_in (m)=0, P InvTarget (m) = -P Load (m)-P grid (m)-P mutual_out (m). P InvTarget A negative value for (m) indicates that the inverter is discharging. The total inverter output (P) Load (m)+P grid (m)+P mutual_out (m) Subject to the rated power P of the inverter invmax limit.

[0184] For equipment shortages: P grid (m)=0, P mutual_out (m)=0, P InvTarget (m)=P mutual_in (m)-P Load (m). If P Load (m)>P mutual_in(m), the result is negative (battery discharging with load); if P Load (m) < P mutual_in (m), the result is positive (battery charging).

[0185] For the balanced device: P grid (m) = 0, P mutual_out (m) = 0, P mutual_in (m) = 0, P InvTarget (m) = -P Load (m).

[0186] Where, when P surplus ≥ MaxGridDischargePower, P grid (i) is provided by the photovoltaic surplus; P mutual_out (i) is allocated by the feed-in and the remaining power after charging; the deficient device can receive the mutual power P mutual_in (i); when P surplus < MaxGridDischargePower, P grid (i) is provided by the photovoltaic surplus and the battery discharge together, the total feed-in target is MaxGridDischargePower, and all surpluses are used for feed-in.

[0187] Through the above process, the remaining mutual power is preferentially supplied to the deficient device with the lowest SOC after completing the feed-in and the photovoltaic direct current charging during the discharging period to promote the battery balancing; the calculation of the inverter target power considers the mutual input, mutual output, feed-in and load four AC side power components, so that the PCS can accurately execute the charging and discharging instructions; the minimum operation of the total mutual power and the total deficient power avoids the excessive allocation to the deficient device, and ensures that the discharging period realizes the self-balancing of internal power mutual under the premise of meeting the grid feed-in target.

[0188] In some embodiments, when the running period is the standby period, the step of step-by-step adjustment further includes the following steps: when the total surplus power is less than the difference between the total deficient power and the preset threshold, increasing the power adjustment value corresponding to the i-th effective energy storage converter; when the total surplus power is greater than the sum of the total deficient power and the preset threshold, decreasing the power adjustment value corresponding to the i-th effective energy storage converter.

[0189] Specifically, P surplus < P deficit -margin (preset threshold), indicating that the total surplus power is significantly less than the total deficient power, indicating that the internal mutual power of the system is insufficient to fill all deficiencies, at which time the power adjustment value of the effective energy storage converter needs to be increased to increase the photovoltaic output and increase the mutual supply.

[0190] If P surplus > Pdeficit +margin indicates that the total surplus power is significantly greater than the total deficit power, which means that there is too much surplus power in the system and there is a risk of backfeeding power to the grid. In this case, the power adjustment value of the effective energy storage converter should be reduced to reduce the photovoltaic output and reduce the mutual assistance supply.

[0191] This mechanism, through the design of a hysteresis range with a preset threshold, ensures that regulation is not triggered when there are small power fluctuations, effectively avoiding frequent reversals of control commands and system oscillations.

[0192] In some embodiments, such as Figure 7 As shown, during the standby period of the running segment, before executing the step adjustment step based on the target gap value in step S160, the following steps S1310 to S1350 are also executed: Step S1310: Allocate the total surplus power to all deficit devices to determine the mutual assistance input power corresponding to each deficit device.

[0193] This step involves allocating the mutual power during standby periods. The total surplus power is distributed to all devices with insufficient power, determining the actual mutual power input that each device can obtain.

[0194] In a specific embodiment, the specific implementation process of step S1310 includes the following steps S1410 to S1440.

[0195] Step S1410: Initialize the third remaining mutual aid power to equal the total surplus power.

[0196] Step S1420: Sort each missing device by its battery state value from low to high and set it as the nth missing device.

[0197] Step S1430: Determine the mutual assistance power corresponding to the nth slack device based on the minimum value among the difference between the rated power and load power of the inverter corresponding to the nth slack device, the absolute value of the net exchange power, and the third remaining mutual assistance power.

[0198] Step S1440: Update the third remaining mutual aid power based on the difference between the third remaining mutual aid power and the mutual aid power corresponding to the nth slack device.

[0199] Specifically, initializing the third residual mutual aid power yields: R mutual3 =P surplus Among them, R mutual3 This is the third remaining mutual aid power.

[0200] According to P mutual3 (n)=min(|P net (n)|,R mutual3 P invmax(n) - P Load (n)) determining the mutual aid power P corresponding to the nth deficient device mutual3 (n).

[0201] According to R mutual3 = R mutual3 - P mutual3 (n), determining the third updated mutual aid power.

[0202] The above process realizes fine allocation of mutual aid power through layer-by-layer screening of three physical constraints, under the hard constraint of zero grid exchange during the standby period, which ensures the priority of low SOC devices to ensure battery balancing, and ensures that the allocation result is safe and executable under multiple boundaries of inverter capacity and total mutual aid amount.

[0203] Step S1320: When the total excess power is greater than the total deficient power, determining the excess power according to the difference between the total excess power and the total deficient power, and reducing the excess power to 0 by reducing the power adjustment value and / or limiting the output power of the photovoltaic module.

[0204] This step is a processing link for power surplus during the standby period. Specifically, two means are adopted to eliminate the excess: one is to reduce the power adjustment step in the step adjustment (to reduce the output of the excess device from the control strategy level), and the other is to directly limit the power generation of the photovoltaic module (to reduce the output from the energy source level). The two ways can be used alone or jointly, and the ultimate goal is to make the excess power zero and realize the accurate balance of the overall energy of the system.

[0205] In a specific embodiment, the specific implementation process of step S1320 includes the following steps S1510 to step S1530.

[0206] Step S1510: According to the order of the actual power of each effective excess device from high to low, each effective excess device is sequentially set as the ath effective excess device, wherein the effective excess device is an effective energy storage converter with a net exchange power greater than 0.

[0207] Step S1520: Reduce the power adjustment value corresponding to the ath effective excess device.

[0208] In a specific embodiment, when the power adjustment value corresponding to the ath effective excess device is reduced, the upper limit value of the power adjustment value reduction per cycle is the down step threshold.

[0209] Step S1530: If the power adjustment value of all effective excess devices has been reduced to 0 and the excess power is still greater than 0, limit the output power of the photovoltaic module corresponding to at least one effective excess device to reduce the excess power to 0.

[0210] Specifically, all available surplus equipment is first sorted from highest to lowest according to the actual photovoltaic power, and each piece of equipment is designated as the a-th available surplus equipment, ensuring that the equipment with the highest photovoltaic output is processed first to reduce excess power in the most efficient way.

[0211] Then, the power adjustment values ​​of each available spare equipment are reduced one by one in the sorted order, so as to gently reduce the output by lowering the photovoltaic target power. This is a soft adjustment method.

[0212] When the power adjustment values ​​of all available surplus equipment have dropped to 0 but excess power still exists, it indicates that soft regulation measures have been exhausted, and hard regulation measures are activated at this point. Specifically, the actual output power of the photovoltaic modules connected to at least one available surplus equipment is limited, forcibly reducing the output until the excess power is completely eliminated.

[0213] Under the hard constraint of zero grid exchange during standby periods, this two-stage regulation mechanism prioritizes the soft regulation method of reducing the power adjustment value to maintain MPPT efficiency and system stability. Only when the soft regulation means are exhausted will the hard measure of limiting photovoltaic output power be activated. This maximizes the maintenance of photovoltaic power generation efficiency and ensures that the system will not feed back power to the grid under any circumstances.

[0214] Step S1330: Determine the inverter target power corresponding to each device in deficit based on the difference between the mutual input power and the load power of each device in deficit.

[0215] Step S1340: Determine the target inverter power corresponding to each surplus device based on the difference between the negative value of the net switching power corresponding to each surplus device and the load power.

[0216] Step S1350: Determine the target inverter power corresponding to each balancing device based on the load power corresponding to each balancing device, wherein the balancing device is an energy storage converter with a net switching power of 0.

[0217] Specifically, any one of the energy storage converters is designated as the l-th energy storage converter, as follows: When the l-th energy storage converter is a deficit device, according to P InvTarget (l) = -P Load (l)+P mutual3 (l) Determine the target inverter power P corresponding to the l-th energy storage converter. InvTarget (l).

[0218] When the l-th energy storage converter is a surplus device, according to P InvTarget (l) = -P Load (l)-P net (l) Determine the target inverter power P corresponding to the l-th energy storage converter. InvTarget (l).

[0219] When the lth energy storage converter is a balanced device, according to P InvTarget (l)=-P Load (l), the inverter target power P InvTarget (l) corresponding to the lth energy storage converter is determined.

[0220] The following is described in three specific embodiments.

[0221] Embodiment one: charging period (insufficient photovoltaic, need to be supplemented by the grid).

[0222] 1. System configuration.

[0223] In this embodiment, the energy storage system includes three energy storage converters PCS1, PCS2 and PCS3.

[0224] PCS1 has no photovoltaic access, the SOC of the battery connected thereto is 30%, the local load power is 0W, the maximum allowable charging power of the battery is 2000W, the rated power of the inverter is 1000W, and the net exchange power thereof is -2000W, belonging to a deficient device.

[0225] PCS2 has no photovoltaic access, the SOC of the battery connected thereto is 60%, the local load power is 0W, the maximum allowable charging power of the battery is1000W, the rated power of the inverter is 1000W, and the netexchange power thereof is -1000W, belonging to a deficient device.

[0226] PCS3 has photovoltaic access, the SOC of the battery connected thereto is 50%, the local load power is 100W, the maximum allowable charging power of the battery is 1500W, the rated power of the inverter is 1000W, the maximum power of the photovoltaic is 3000W, the initial actual power of the photovoltaic is 1600W, and the net exchange power thereof is 0W, belonging to a balanced device.

[0227] The maximum grid charging power MaxGridChargePower is set to 1500W, the up-step threshold Δup=the down-step threshold Δdown=50W, the preset upper threshold UpThrd=0.95, and the preset lower threshold DownThrd=0.85. The illumination condition is that the illumination of PCS3 is sufficient, and the actual output can always reach the target value.

[0228] 2. Initial period (t=0).

[0229] 2.1. Initial state.

[0230] The initial power adjustment value P adj (3) of PCS3 is 0. PCS3 calculates the photovoltaic target power P PvTarget (3)=P BmsMax (3)+ PLoad (3) + P adj (3), i.e. 1500 + 100 + 0 = 1600W. The actual output P ActPV (3) is 1600W, then P net (3) = 1600 - 100 - 1500 = 0W.

[0231] The data reported by each device is as follows: PCS1 is an invalid energy storage converter, SOC is 30%, P ActPV is 0W, P net is -2000W. PCS2 is an invalid energy storage converter, SOC is 60%, P ActPV is 0W, P net is -1000W. PCS3 is a valid energy storage converter, SOC is 50%, P ActPV is 1600W, P net is 0W.

[0232] 2.2, Statistics and step adjustment.

[0233] The EMS performs statistical calculation according to the data reported by each device. The total surplus power P surplus is 0, and the total deficit power P deficit is 3000W. Since P surplus is 0W, which is less than 3000W of P deficit , the photovoltaic is insufficient, and the remaining gap is supplemented by the power grid.

[0234] The target gap value P deficit -P surplus = 3000 - 0 = 3000W, i.e. R1 = 3000W.

[0235] According to step S310, the SOC corresponding to each valid energy storage converter is sorted from low to high. Since PCS1 and PCS2 have no photovoltaic, their power adjustment values remain 0. For PCS3, according to step S420, when the target gap value is greater than 0 and the net exchange power is greater than or equal to 0, if the step feedback ratio is greater than or equal to the preset upper threshold, calculate its power adjustment value increment Δup = min(Δup, R1) = min(50, 3000) = 50W, then P adj (3) = min(P adj (3) + Δup, MaxPvPower(3)) = min(0 + 50, 1000) = 50W. Update the target gap value R1 = 3000 - 50 = 2950W. Note: the upper limit of P adj (3) is 900W (P invmax (3) - P Load (3) = 1000 - 100 = 900W), and the inverter will be overloaded if it exceeds this value.

[0236] 2.3, Mutual aid distribution.

[0237] According to step S510, the total surplus power is distributed to each deficit device. Since P surplus = 0, there is no power available for mutual aid, P mutual = 0, and P mutual = 0. mutual = 0.

[0238] 2.4, Grid charging power distribution.

[0239] According to steps S710 to S730, the total grid charging power P GridChargeTotal = min(R1, MaxGridChargePower) = min(2950, 1500) = 1500 W. According to step S620, the deficit devices are ordered by SOC from low to high, i.e. PCS1 (30%) is prioritized over PCS2 (60%).

[0240] For PCS1, its grid charging power P GridAlloc (1) = min(|P net (1)|, P GridChargeTotal , P invmax (1) - P Load (1)) = min(2000, 1500, 1000) = 1000 W, and the remaining grid charging power is updated to 1500 - 1000 = 500 W For PCS2, its grid charging power P GridAlloc (2) = min(|P net (2)|, 500, 1000) = 500 W, and the remaining grid charging power is updated to 500 - 500 = 0 W.

[0241] The grid charging power P GridAlloc (3) for PCS3 is 0.

[0242] 2.5, Issue instructions.

[0243] According to step S540, the target inverter power P InvTarget (i) = -P Load (i) + P mutual (i) + P GridAlloc (i) is calculated for each device.

[0244] The P Load for PCS1 is 0 W, the P mutual is 0 W, and the P GridAlloc is 1000 W, and its inverter target power is +1000 W, meaning charging 1000 W.

[0245] PCS2's P Load is 0W, P mutual is 0W, P GridAlloc is 500W, its inverter target power is +500W, meaning charging 500W.

[0246] PCS3's P Load is 100W, P mutual is 0W, P GridAlloc is 0W, its inverter target power is -100W, meaning inverter output 100W for local load. PCS3's P adj (3) is updated to 50W, which takes effect in the next cycle.

[0247] 3. Step adjustment process (cycle 1 and subsequent cycles).

[0248] In each adjustment cycle, PCS3's P adj (3) is increased by 50W until P adj (3) reaches 900W, the inverter output reaches the inverter upper limit of 1000W, and the command in step S540 is executed in each cycle.

[0249] In cycle 0, PCS3's actual photovoltaic power is 1600W, its own BMS charging power is 1500W, and the inverter target power is -100W; PCS1's grid charging power is 1000W, mutual aid power is 0W, and the inverter target power is +1000W; PCS2's grid charging power is 500W, mutual aid power is 0W, and the inverter target power is +500W; the target gap value R1 is 2950W, which is the initial state, and the grid charging is the main.

[0250] In cycle 1, PCS3's actual photovoltaic power rises to 1650W, its own BMS charging power remains 1500W, and the inverter target power is -150W; PCS1's grid charging power is 950W, mutual aid power is 50W, and the inverter target power remains +1000W; PCS2's grid charging power is 550W, mutual aid power is 0W, and the inverter target power is +550W; R1 drops to 2900W, and PCS3 starts to have surplus power for mutual aid.

[0251] In cycle 2, PCS3's actual photovoltaic power rises to 1700W, and the inverter target power is -200W; PCS1's grid charging power is 900W, and mutual aid power is 100W; PCS2's grid charging power is 600W, R1 drops to 2850W, and PCS3's mutual aid power continues to increase.

[0252] At cycle 3, the photovoltaic actual power of PCS3 rises to 1750W, and the inverter target power is -250W; the grid charging power of PCS1 is 850W, and the mutual aid power is 150W; the grid charging power of PCS2 is 650W, and R1 falls to 2800W.

[0253] At cycle 4, the photovoltaic actual power of PCS3 rises to 1800W, and the inverter target power is -300W; the grid charging power of PCS1 is 800W, and the mutual aid power is 200W; the grid charging power of PCS2 is 700W, and R1 falls to 2750W.

[0254] Thereafter, the photovoltaic actual power of PCS3 continues to increase by 50W every cycle until reaching a steady state. At the steady state, the photovoltaic actual power of PCS3 is 2500W, the self BMS charging power is 1500W, and the inverter target power is -1000W; the grid charging power of PCS1 is 100W, the mutual aid power is 900W, and the inverter target power is +1000W; the grid charging power of PCS2 is 1000W, the mutual aid power is 0W, and the inverter target power is +1000W; R1 is 2100W, and the inverter outputs at full capacity, and the system reaches a steady state. The unit is W, and a positive value indicates charging and a negative value indicates discharging. The self BMS charging of PCS3 is completed at the DC side and does not pass through the inverter, and is not reflected in P InvTarget

[0255] 4. Issue instructions and trends.

[0256] Step S540 of issuing instructions is performed every control cycle.

[0257] At cycle 0, P adj (3) is 50W, the inverter target power of PCS1 is +1000W, the inverter target power of PCS2 is +500W, the inverter target power of PCS3 is -100W, and the mutual aid output of PCS3 is 0W, which is the initial state, and PCS3 only carries the local load.

[0258] At cycle 1, P adj (3) rises to 100W, the inverter target power of PCS2 rises to +550W, the inverter target power of PCS3 becomes -150W, and the mutual aid output of PCS3 is 50W, and PCS3 starts to discharge mutual aid.

[0259] At cycle 2, P adj (3) rises to 150W, the inverter target power of PCS2 rises to +600W, the inverter target power of PCS3 becomes -200W, and the mutual aid output of PCS3 is 100W.

[0260] At cycle 3, P adj ​(3) up to 200W, PCS2 inverter target power up to +650W, PCS3 inverter target power becomes -250W, PCS3 grid export is 150W.

[0261] At cycle 4, P adj (3) up to 250W, PCS2 inverter target power up to +700W, PCS3 inverter target power becomes -300W, PCS3 grid export is 200W.

[0262] Every cycle P adj (3) continues to increase by 50W until steady state at P adj (3) up to 900W, PCS1 inverter target power is +1000W, PCS2 inverter target power is +1000W, PCS3 inverter target power is -1000W, PCS3 grid export is 900W, inverter full power output, system reaches steady state.

[0263] 5. Steady state conditions.

[0264] At steady state, P adj (3) = 900W.

[0265] The power distribution for PCS3 is as follows: photovoltaic output 2500W, of which 1500W is used for self BMS charging (DC side, already at P BmsMax (3) = 1500W upper limit), and the remaining 1000W enters the inverter side (AC side). The inverter outputs 1000W (already at P invmax (3) = 1000W upper limit), of which 100W is supplied to the local load, and 900W is used for grid export. The net exchange power P net (3) for PCS3 is P ActPV (3) - P Load (3) - P BmsMax (3) = 2500 - 100 - 1500 = 900W, inverter target power P InvTarget (3) = -P Load (3) + P mutual (3) + P GridAlloc (3) = -100 - 900 - 0 = -1000W.

[0266] PCS1 is a deficit device, P net (1) = -2000W, of which 900W is grid export, and 100W is grid charging, for a total charging power of 900 + 100 = 1000W, which has reached the inverter upper limit. Inverter target power P InvTarget (1) = -P Load (1) + P mutual (1) + P GridAlloc(1) = -0 + 900 + 100 = +1000W.

[0267] PCS2 is a deficient device, P net (2) = -1000W, mutual aid received is 0W (mutual aid power has been fully allocated to PCS1), grid charging is 1000W, total charging power is 0 + 1000 = 1000W, which has reached the upper limit of the inverter. The target power of the inverter P InvTarget (2) = -P Load (2) + P mutual (2) + P GridAlloc (2) = -0 + 0 + 1000 = +1000W.

[0268] The steady-state power of the three devices is as follows: the photovoltaic output of PCS1 is 0W, the photovoltaic DC charging is 0W, the local load is 0W, the mutual aid received is 900W, the mutual aid output is 0W, the grid charging is 100W, and the target power of the inverter is +1000W. The photovoltaic output of PCS2 is 0W, the photovoltaic DC charging is 0W, the local load of PCS2 is 0W, the mutual aid received is 0W, the mutual aid output is 0W, the grid charging is 1000W, and the target power of the inverter is +1000W. The photovolta ic output of PCS3 is 2500W, the photovoltaic DC charging is 1500W, the local load is 100W, the mutual aid received is 0W, the mutual aid output is 900W, the grid charging is 0W, and the target power of the inverter is -1000W.

[0269] The steady-state results are as follows: PCS1 charges 1000W (mutual aid 900W + grid 100W), which has reached the upper limit of the inverter; PCS2 charges 1000W (all from the grid), which has reached the upper limit of the inverter; PCS3 photovoltaic output is 2500W, of which 1500W is DC charging, 100W is local load, 900W is mutual aid output, and the inverter is full 1000W output. The total grid charging is 100W + 1000W = 1100W, which does not exceed the MaxGridChargePower = 1500W limit.

[0270] 6、Summary.

[0271] First, the step S540 is executed every control cycle to issue instructions, P InvTarget It is dynamically updated with the change of PV output, and it is issued once every cycle.

[0272] Second, the charging allocation follows the principle of low SOC priority, PCS1 (SOC = 30%) is given priority to mutual aid and grid charging, and PCS2 (SOC = 60%) is given priority.

[0273] Third, step adjustment gradually increases photovoltaic output, P adj (3) increase 50W per cycle until reach the upper limit 900W (Pinvmax -P Load =1000-100=900 W), the system achieves power balance.

[0274] Fourth, hardware constraints are effectively handled, and the total output of the inverter is equal to the sum of the local load and the mutual aid output, subject to the P invmax limit. When PCS1 cannot absorb more charging power due to the upper limit of the inverter, the grid charging is automatically transferred to the PCS2 of the next priority.

[0275] Fifth, the SOC balancing effect is significant, and the device with the lowest SOC (PCS1, 30%) obtains mutual aid priority, and finally both devices with insufficient capacity reach the inverter upper limit of 1000 W charging, the system power balance, and the control logic is self-consistent.

[0276] This embodiment fully demonstrates the whole process of the charging period under insufficient photovoltaic conditions, in which the EMS gradually increases the photovoltaic output through step feedback, and allocates mutual aid power first and then grid charging power according to the SOC priority (low SOC priority). When allocating mutual aid power and grid charging power, the rated capacity limit of each device is fully considered. When PCS1 cannot absorb more charging power due to the upper limit of the inverter, grid charging is automatically transferred to the PCS2 of the next priority, achieving reasonable allocation between devices with insufficient capacity. Finally, in the steady state, PCS1 charges at the inverter upper limit of 1000 W (mutual aid 900 W + grid 100 W), PCS2 charges at 1000 W (all from the grid), and PCS3 outputs at the inverter full capacity of 1000 W (local load 100 W + mutual aid output 900 W), the system power balance, and the device with the lowest SOC obtains priority charging. All inverter target powers are correctly signed (positive for charging and negative for discharging), the control logic is self-consistent, and the effectiveness and SOC balancing ability of the present application under hardware constraints are verified.

[0277] Example Two: Discharging Period

[0278] Example 1: Sufficient photovoltaic (no battery discharging)

[0279] 1. System configuration

[0280] In this embodiment, the energy storage system includes three energy storage converters PCS1, PCS2 and PCS3.

[0281] PCS1 has photovoltaic access, and the corresponding battery SOC is 80%, the local load power is 200 W, the maximum allowed charging power of the battery is 200 W, the inverter rated power is 1000 W, the initial photovoltaic actual power is 1000 W, and the maximum photovoltaic power is 1200 W.

[0282] PCS2 has photovoltaic (PV) access, with a corresponding battery SOC of 60%, a local load power of 300W, a maximum allowable battery charging power of 500W, an inverter rated power of 1000W, an initial actual PV power of 1000W, and a maximum PV power of 1400W.

[0283] PCS3 has photovoltaic access, with a corresponding battery SOC of 30%, a local load power of 700W, a maximum allowable battery charging power of 800W, an inverter rated power of 1000W, and an initial actual photovoltaic power of 600W.

[0284] The maximum grid discharge power (MaxGridDischargePower) is preset to 1200W. When distributing discharge power, it is first sorted by net exchange power from highest to lowest; if the net exchange power is equal, it is then sorted by State of Charge (SOC) from highest to lowest (higher SOC discharges first). The illumination conditions are such that the actual output of all devices reaches the target value, with initial P... adj (i)=0. Discharge time period, P net (i)=P ActPV (i)-P Load (i). P charge (Self-charged BMS) is completed on the DC side, without going through the inverter, and is not reflected in P. InvTarget middle.

[0285] 2. Execution process (cycle 0).

[0286] In step S150, system power statistics are obtained. PCS1's P net (1) = 1000 - 200 = 800W, which is surplus equipment. PCS2's P net (2) = 1000 - 300 = 700W, which is surplus equipment. PCS3's P net (3) = 600 - 700 = -100W, representing the equipment in short supply. The total surplus power P of the system. surplus =800+700=1500W, the total power deficit of the system P deficit =100W. Because P surplus If 1500W is greater than or equal to 1200W of MaxGridDischargePower, proceed to step S820.

[0287] According to step S810, the surplus equipment is arranged in descending order of net exchange power, with PCS1 (800W, 80%) taking precedence over PCS2 (700W, 60%).

[0288] According to step S820, the first feed target power P is initialized. G1 =1200W.

[0289] The upper limit of the power supply for PCS1 is Pinvmax (1)-P Load (1)=100 0-200=800W, its feeding power P grid (1)=min(800, 800, 1200)=800W, update P G1 =1200-800=400W, its remaining power after feeding is 800-800=0W.

[0290] The upper limit of the feeding of PCS2 is P invmax (2)-P Load (2)= 1000-300=700W, its feeding power P grid (2)=min(700, 400, 700)=400W, update P G1 =400-400=0W, its remaining power after feeding is 700-400=300W.

[0291] PCS3 is a deficient device and does not participate in the feeding distribution, its P grid (3)=0W.

[0292] The feeding target is achieved and the distribution is stopped. The remaining available power of each device is: PCS1 is 0W, PCS2 is 300W, and PCS3 is 0W.

[0293] According to step S940, only PCS2 has remaining power 300W, and PCS2 charges its own battery (DC side, not through the inverter) with its own remaining power, P charge (2)=300W. The remaining available power of each device after distribution is 0W. According to step S840, P mutual_avail =0W, no mutual aid output. Mutual aid gap judgment: P mutual_avail is 0W less than 100W of P deficit , there is a mutual aid gap R1=100-0=100W, and the step adjustment step is called.

[0294] According to step S1140, the instructions are issued. P Load of PCS1 is 200W, P grid of PCS1 is 800W, P mutual_out of PCS1 is 0W, and the target power of the inverter of PCS1 is -1000W, which means that the total output of the inverter is 1000W (load 200W+feeding 800W). P Load of PCS2 is 300W, P grid of PCS2 is 400W, P mutual_out of PCS2 is 0W, and the target power of the inverter of PCS2 is -700W, which means that the total output of the inverter is 700W (load 300W+feeding 400W). P Load of PCS3 is 700W, P grid of PCS3 is 0W, and Pmutual_out For 0W, its inverter target power is -700W, meaning that the inverter outputs 700W in total (700W for load, 700W for discharging from battery). The total grid feeding power is 800+400=1200W, reaching MaxGridDischargePower.

[0295] 3. Step adjustment process (period 1~6).

[0296] In each adjustment period, EMS issues a +50W instruction to PCS1 and PCS2 at the same time (parallel issue), and each period executes step S1140 to issue the instruction.

[0297] The key constraint is that the total grid feeding power remains 1200W constant; the upper limit of PCS1 feeding power is P invmax (1)-P Load (1)= 1000-200=800W; the upper limit of PCS2 feeding power is P invmax (2)-P Load (2)= 1000-300=700W; the upper limit of MaxPvPower(1) of PCS1 is 1200W; the upper limit of MaxPvPower(2) of PCS2 is 1400W; the newly added PV power is allocated according to priority, that is, when the total feeding power is less than 1200W, it is preferentially fed, followed by photovoltaic DC charging, and finally mutual aid output.

[0298] Period 0 is the initial state, P adj are all 0, the actual PV power of PCS1 is 1000W, the feeding power is 800W, and the photovoltaic DC charging is 0W; the actual PV power of PCS2 is 1000W, the feeding power is 400W, the photovoltaic DC charging is 300W, and the mutual aid output is 0W. The total feeding power is 1200W, R1 is 100W, and the inverter target powers of the three devices are -1000W, -700W and -700W respectively.

[0299] In period 1, PCS1 and PCS2 each obtain a +50W P adj , the actual PV power of PCS1 rises to 1050W, and the photovoltaic DC charging rises to 50W; the actual PV power of PCS2 rises to 1050W, and the photovoltaic DC charging rises to 350W. The total feeding power remains 1200W, R1 remains 100W, and the inverter target power remains unchanged.

[0300] In period 2, PCS1 and PCS2 each obtain a +50W P adj , the actual PV power of PCS1 rises to 1100W, and the photovoltaic DC charging rises to 100W; the actual PV power of PCS2 rises to 1100W, and the photovoltaic DC charging rises to 400W.

[0301] Period 3, PCS1 and PCS2 each obtain +50W of P adj PCS1 photovoltaic actual power rises to 1150W, photovoltaic DC charging rises to 150W, PCS2 photovoltaic actual power rises to 1150W, photovoltaic DC charging rises to

[0302] Period 4, PCS1 and PCS2 each obtain +50W of P adj PCS1 photovoltaic actual power rises to 1200W, photovoltaic DC charging rises to 200W, reaching the upper limit of PBmsMax(1); PCS2 photovoltaic actual power rises to 1200W, photovoltaic DC charging rises to

[0303] Period 5, only PCS2 obtains +50W of P adj (PCS1 has reached the PV upper limit), PCS2 photovoltaic actual power rises to 1250W, photovoltaic DC charging remains at 500W, which has reached the upper limit, adds 50W to mutual aid output, mutual aid output rises to 50W, R1 falls to 50W, PCS2 inverter target power becomes -750W, and PCS3 inverter target power becomes -650W.

[0304] Period 6, only PCS2 obtains +50W of P adj PCS2 photovoltaic actual power rises to 1300W, photovoltaic DC charging remains at 500W, mutual aid output rises to 100W, R1 falls to 0W, and stepping stops. PCS2 inverter target power becomes -800W, and PCS3 inverter target power becomes -600W.

[0305] 4. Issue instruction change trend.

[0306] Each adjustment period executes step S1140 to issue instructions. The final stable state is: The initial photovoltaic actual power of PCS1 is 1000W, and the cumulative P adj (1) is +200W, the final photovoltaic actual power is 1200W, the local load is 200W, the feed power is 800W, the photovoltaic DC charging is 200W, the mutual aid output is 0W, and the final inverter target power is -1000W, which has reached the upper limits of MaxPvPower(1) and PBmsMax(1).

[0307] The initial photovoltaic actual power of PCS2 is 1000W, and the cumulative P adj(2) is +300W, the final actual power of the photovoltaic is 1300W, the local load is 300W, the power supply is 400W, the photovoltaic DC charging is 500W, the mutual output is 100W, and the final inverter target power is -800W, which has reached the upper limit of PBmsMax(2).

[0308] The initial actual photovoltaic power of PCS3 is 600W, and the cumulative P adj (3) is 0W, the final actual photovoltaic power is 600W, the local load is 700W, the feed power is 0W, the photovoltaic DC charging is 0W, the mutual aid output is 0W, and the final inverter target power is -600W, the shortfall has been supplemented by mutual aid.

[0309] P InvTarget The meaning is: a negative value indicates that the inverter is discharging (power supply or mutual assistance output), and a positive value indicates that the inverter is charging (mutual assistance reception). P charge (Self-charged BMS) is completed on the DC side, without going through the inverter, and is not reflected in P. InvTarget The total power fed into the grid is 800 + 400 = 1200W, reaching the MaxGridDischargePower. PCS2's 100W output is completely transferred to PCS3, fully compensating for PCS3's shortfall. After receiving the 100W from the grid, PCS3 still needs to discharge 600W from the battery to supply the remaining load (700W load - 100W grid transfer = 600W).

[0310] 5. Complete explanation of power flow direction (taking the final cycle 6 as an example).

[0311] PCS1 is a spare device, P net (1) = 800W. Its photovoltaic output is 1200W, of which 200W supplies the local load, 800W is fed into the grid (after the inverter, reaching the inverter's power supply limit), and 200W charges its own battery (DC side, without going through the inverter, reaching P). BmsMax (1) = 200W upper limit), mutual aid output is 0W, inverter target power is -1000W.

[0312] PCS2 is a spare device, P net (2) = 700W. Its photovoltaic output is 1300W, of which 300W supplies the local load, 400W is fed into the grid (through the inverter), and 500W charges its own battery (DC side, without going through the inverter, already reaching P). BmsMax (2) = 500W upper limit), 100W mutual aid output to PCS3 (through inverter), the inverter target power is -800W.

[0313] PCS3 is a missing device, P net(3) = -100 W. Its photovoltaic output is 600 W, the local load demand is 700 W, the photovoltaic output is insufficient, and 100 W is received from PCS2 for mutual aid (through the inverter, the charging direction), and the shortage is completely supplemented by mutual aid, and the target power of the inverter is -600 W.

[0314] 6. Power balance check (final period).

[0315] The input of PCS1 is photovoltaic 1200 W, and the output is load 200 W plus feed 800 W plus charging 200 W, totaling 1200 W, power balance. The input of PCS2 is photovoltaic 1300 W, and the output is load 300 W plus feed 400 W plus charging 500 W plus mutual aid 100 W, totaling 1300 W, power balance. The input of PCS3 is photovoltaic 600 W plus mutual aid 100 W, and the output is load 700 W, totaling 700 W, power balance. The total grid feed-in is 800 plus 400, which equals 1200 W, meeting the requirement.

[0316] Inverter capacity check: the load 200 W of PCS1 plus the feed 800 W equals 1000 W, which does not exceed the rated power 1000 W of the inverter. The load 300 W of PCS2 plus the feed 400 W plus the mutual aid output 100 W equals 800 W, which does not exceed the rated power 1000 W of the inverter. The PCS3 load 700 W minus the mutual aid input 100 W equals 600 W, which does not exceed the rated power 1000 W of the inverter. All meet the capacity constraints.

[0317] 7. Summary.

[0318] First, each step period executes the instruction under step S1140, P InvTarget Dynamic update with PV output change, issued once per period.

[0319] Second, the total grid feed-in power remains constant at 1200 W, and the sum of the feeds of PCS1 and PCS2 always equals MaxGridDischargePower.

[0320] Third, step adjustment is executed in two stages. In stage one (periods 1 to 4), the PV output of PCS1 and PCS2 is increased synchronously from 1000 W to 1200 W, and the PCS1 photovoltaic DC charging is increased from 0 to 200 W (reaching P BmsMax (1) upper limit), and the PCS2 photovoltaic DC charging is increased from 300 W to 500 W (reaching P BmsMax (2) upper limit). In stage two (periods 5 to 6), the PCS2 charging has reached the upper limit, the new output is diverted to mutual aid output, which is increased from 0 to 100 W, and R1 is gradually reduced from 100 W to 0 W, and the mutual aid gap is completely filled.

[0321] Fourth, PV power goes to completion. PCS1's PV increases from 1000W to 1200W, an increase of 200W, reaching the MaxPvPower(1) upper limit, feeds 800W, charges 200W (reaching the PBmsMax(1) upper limit). PCS2's PV increases from 1000W to 1300W, an increase of 300W, feeds 400W, charges 500W (reaching the PBmsMax(2) upper limit), and shares 100W.

[0322] Fifth, the sharing power goes to completion. PCS2's 100W sharing output goes to completion to PCS3, and PCS3's shortage is made up.

[0323] Sixth, the SOC balancing effect is good. The high SOC device (PCS1, 80%) prioritizes feeding, the medium SOC device (PCS2, 60%) undertakes the main charging and sharing output, and the low SOC device (PCS3, 30%) receives the sharing charging.

[0324] Example 2: PV is insufficient (battery discharging is needed to make up).

[0325] 1. System configuration.

[0326] In this embodiment, PCS1 has no PV access, the SOC is 80%, the local load power is 200W, the maximum allowable charging power of the battery is 200W, the maximum allowable discharging power of the battery is 800W, the inverter rated power is 1000W, and the actual PV power is 0W.

[0327] PCS2 has PV access, the SOC is 60%, the local load power is 300W, the maximum allowable charging power of the battery is 400W, the maximum allowable discharging power of the battery is 600W, the inverter rated power is 1000W, the maximum PV power is 1200W, and the initial actual PV power is 900W.

[0328] PCS3 has PV access, the SOC is 40%, the local load power is 500W, the maximum allowable charging power of the battery is 600W, the maximum allowable discharging power of the battery is 400W, the inverter rated power is 1000W, the maximum PV power is 1 200W, and the initial actual PV power is 800W.

[0329] Parameter description: MaxPvPower is the maximum available power of the PV module under the current light condition (physical upper limit), which is limited by step adjustment.

[0330] PCS2 currently generates 900W, with a maximum of 1200W, and can increase by a maximum of 300W by step. PCS3 currently generates 800W, with a maximum of 1200W, and can increase by a maximum of 400W by step.

[0331] The inverter output constraint is PLoad (i) + P grid (i) + P mutual_out (i) ≤ P invmax (i), PV exceeds inverter output capability can be through P charge (i) absorption, not subject to P invmax Limit.

[0332] Set MaxGridDischargePower = 1600W, Δup = Δdown = 50W, UpThrd = 0.95, DownThrd = 0.85.

[0333] The sorting rule is: the photovoltaic power distribution is sorted by P net from high to low; the battery discharge distribution is sorted by SOC from high to low. The light condition is that all devices can actually output the target value, and the initial P adj (i) = 0. The discharge time period, P net (i) = P ActPV (i) - P Load (i).

[0334] 2, Execution process (initial period 0).

[0335] In step S150, the system power statistics are obtained.

[0336] The P net (1) of PCS1 = 0-200 = -200W, which is a deficient device.

[0337] The P net (2) of PCS2 = 900-300 = 600W, which is a surplus device.

[0338] The P net (3) of PCS3 = 800-500 = 300W, which is a surplus device.

[0339] The total surplus P surplus of the system = 600+300 = 900W, and the total deficiency P deficit of the system = 200W. Since P surplus is 900W, which is less than MaxGridDischargePower of 1600W, step S830 is executed.

[0340] According to step S830, all photovoltaic surpluses are used for power feeding, and P G2 = P surplus = 900W is initialized. The sorting is that PCS2 (600W) is preferred to PCS3 (300W).

[0341] The upper limit of the power feeding of PCS2 is P invmax (2) - PLoad (2) = 1000 - 300 = 700 W, its photovoltaic feed power P grid_pv (2) = min(600, 900, 700) = 600 W, update P G2 = 900 - 600 = 300 W.

[0342] The upper feed limit of PCS3 is P invmax (3) - P Load (3) = 1000 - 500 = 500 W, its photovoltaic feed power P grid_pv (3) = min(300, 300, 500) = 300 W, update P G2 = 300 - 300 = 0 W.

[0343] PCS1 is the deficient device, P grid_pv (1) = 0. All photovoltaic surpluses have been allocated, but the total feed power is still insufficient MaxGridDischargePower.

[0344] Perform battery discharge to supplement the remaining deficiency. The remaining feed deficiency R batt = 1600 - 900 = 700 W. The order is PCS1 (80%) first, PCS2 (60%) second, and PCS3 (40%) third. Initialize R batt = 700 W. The inverter remaining capacity of PCS1 is P invmax (1) - P Load (1) - P grid_pv (1) = 1000 - 200 - 0 = 800 W, its dischargeable power is min(700, 800, 800) = 700 W, update R batt = 700 - 700 = 0 W. PCS2 and PCS3 are not allocated discharge power because R batt has been 0.

[0345] The total feed power of each device is: P grid (1) = 0 + 700 = 700 W for PCS1, P grid (2) = 600 + 0 = 600 W for PCS2, and P grid (3) = 300 + 0 = 300 W for PCS3.

[0346] Inverter output check: the load of 200 W plus the feed of 700 W of PCS1 equals 900 W, which does not exceed 1000 W; the load of 300 W plus the feed of 600 W of PCS2 equals 900 W, which does not exceed 1000 W; the load of 500 W plus the feed of 300 W of PCS3 equals 800 W, which does not exceed 1000 W, all of which satisfy the capacity constraint.

[0347] Since all photovoltaic surplus has been fully used for feeding, P charge (1), P charge (2), and P charge (3) are all 0, P mutual_avail is 0, all mutual aid outputs and mutual aid inputs are 0. The mutual aid gap is judged to be P mutual_avail (0W) < P deficit (200W), there is a mutual aid gap R1 = 200-0 = 200W. The step adjustment step is executed, the photovoltaic output is increased by a positive step, the goal is to close the mutual aid gap, and the output continues to increase until all go to saturation.

[0348] According to the instruction issued under step S1140 (period 0). P Load of PCS1 is 200W, P grid of PCS1 is 700W, P mutual_out (1) of PCS1 is 0W, P mutual_in (1) of PCS1 is 0W, the inverter target power P InvTarget (1) of PCS1 is -900W, which means that the battery discharges 900W (200W load + 700W inverter output).

[0349] P Load of PCS2 is 300W, P grid of PCS2 is 600W, the inverter target power P InvTarget (2) of PCS2 is -900W, which means that the photovoltaic output is 900W (300W load + 600W feeding).

[0350] P Load of PCS3 is 500W, P grid of PCS3 is 300W, the inverter target power P InvTarget (3) of PCS3 is -800W, which means that the photovoltaic output is 800W (500W load + 300W feeding).

[0351] The total feeding grid power is 700+600+300=1600W, reaching MaxGridDischargePower.

[0352] 3, Step adjustment process (period 1~8).

[0353] The key constraints are: the upper limit of the feeding of PCS2 is P invmax (2)-P Load (2)= 1000-300=700W, the current 600W, there are 100W incremental space; the upper limit of the feeding of PCS3 is P invmax (3)-P Load(3)=1000-500=500W, current 300W, 200W incremental space; MaxPvPower(2) of PCS2 upper limit is 1200W; MaxPvPower(3) of PCS3 upper limit is 1200W; PBmsMax(2) of PCS2 upper limit is 400W; PBmsMax(3) of PCS3 upper limit is 600W. In each regulation period, EMS simultaneously issues a +50W instruction to PCS2 and PCS3 (parallel issue), and each period executes step S1140 to issue the instruction.

[0354] Period 0 is the initial state, the PCS1 feeding power is 700W; the PCS2 photovoltaic actual power is 900W, the feeding power is 600W, the photovoltaic DC charging is 0W; the PCS3 photovoltaic actual power is 800W, the feeding power is 300W, the photovoltaic DC charging is 0W. The total feeding is 1600W, R1 is 200W, and the inverter target powers of the three devices are -900W, -900W and -800W, respectively.

[0355] In period 1, PCS2 and PCS3 each obtain a +50W P adj , the PCS2 photovoltaic actual power rises to 950W, the feeding power rises to 650W, the PCS3 photovoltaic actual power rises to 850W, the feeding power rises to 350W, the total PV feeding increases by 100W, the PCS1 battery discharges by 100W, the PCS1 feeding power decreases to 600W, and the inverter target powers become -800W, -950W and -850W.

[0356] In period 2, PCS2 and PCS3 each obtain a +50W P adj , the PCS2 photovoltaic actual power rises to 1000W, the feeding power rises to 700W (reaching the feeding upper limit), the PCS3 photovoltaic actual power rises to 900W, the feeding power rises to 400W, the PCS1 feeding power decreases to 500W, and the PCS1 inverter target power becomes -700W, and the PCS2 inverter target power becomes -1000W.

[0357] In period 3, PCS2 and PCS3 each obtain a +50W P adj , the PCS2 photovoltaic actual power rises to 1050W, the feeding power remains 700W and reaches the upper limit, and the photovoltaic DC charging rises to 50W, the PCS3 photovoltaic actual power rises to 950W, the feeding power rises to 450W, the total feeding is still 1600W, the PCS1 feeding power decreases to 450W, the PCS1 inverter target power becomes -650W, the PCS2 inverter target power is -1000W, and the PCS3 inverter target power is -950W.

[0358] At cycle 4, PCS2 and PCS3 each obtain +50W of P adj PCS2 photovoltaic actual power rises to 1100W, feed power remains 700W, photovoltaic DC charging rises to 100W, PCS3 photovoltaic actual power rises to 1000W, feed power rises to 500W (reached the upper limit of feed), PCS1 feed power drops to 400W, PCS1 inverter target power becomes -600W, and PCS3 inverter target power becomes -1000W.

[0359] At cycle 5, PCS2 and PCS3 each obtain +50W of P adj PCS2 photovoltaic actual power rises to 1150W, feed power remains 700W, photovoltaic DC charging rises to 150W, PCS3 photovoltaic actual power rises to 1050W, feed power remains 500W, photovoltaic DC charging rises to 50W, and PCS1 feed power remains 400W unchanged, and inverter target power remains unchanged.

[0360] At cycle 6, PCS2 and PCS3 each obtain +50W of P adj PCS2 photovoltaic actual power rises to 1200W (reached the upper limit of PV), feed power remains 700W, photovoltaic DC charging rises to 200W, PCS3 photovoltaic actual power rises to 1100W, feed power remains 500W, photovoltaic DC charging rises to 100W, and PCS1 feed power remains 400W.

[0361] At cycle 7, only PCS3 obtains +50W of P adj (reached the upper limit of PV), PCS3 photovoltaic actual power rises to 1150W, and photovoltaic DC charging rises to 150W.

[0362] At cycle 8, only PCS3 obtains +50W of P adj PCS3 photovoltaic actual power rises to 1200W (reached the upper limit of PV) and photovoltaic DC charging rises to 200W, and the stepping stops. The final PCS1 feed power is 400W, PCS2 photovoltaic actual power is 1200W, feed power is 700W, and photovoltaic DC charging is 200W, and PCS3 photovoltaic actual power is 1200W, feed power is 500W, and photovoltaic DC charging is 200W.

[0363] 4. Issue instruction change trend.

[0364] Each adjustment cycle executes step S1140 of issuing instructions. The final stable state is: PCS1 has initial PV of 0 W, final PV of 0 W, local load of 200 W, grid feed of 400 W, PV DC charging of 0 W, mutual aid output of 0 W, mutual aid input of 0 W, inverter target power of -600 W, and state of battery discharge 600 W (200 W load + 400 W inverter output).

[0365] PCS2 has initial PV of 900 W, final PV of 1200 W, local load of 300 W, grid feed of 700 W, PV DC charging of 200 W, mutual aid output of 0 W, mutual aid input of 0 W, inverter target power of -1000 W, and state of reach PV upper limit (300 W load + 700 W grid feed).

[0366] PCS3 has initial PV of 800 W, final PV of 1200 W, local load of 500 W, grid feed of 500 W, PV DC charging of 200 W, mutual aid output of 0 W, mutual

[0367] The total grid feed is 400 + 700 + 500 = 1600 W, which reaches MaxGridDischargePower. After step adjustment, the battery discharge of PCS1 is reduced from 700 W to 400 W (300 W reduction), and the PV output of PCS2 and PCS3 is increased by 300 W and 400 W respectively, effectively reducing the battery discharge requirement.

[0368] 5. Complete power flow description (take the final period 8 as an example).

[0369] PCS1 is a deficient device, Pnet(1) = -200 W. Its battery discharge of 600 W passes through the inverter, of which 200 W is supplied to the local load and 400 W is fed into the grid, and the inverter target power is -600 W. net (1) = -200 W. Its battery discharge of 600 W passes through the inverter, of which 200 W is supplied to the local load and 400 W is fed into

[0370] PCS2 is a surplus device, Pnet(2) = 900 W. Its PV output of 1200 W, of which 300 W is supplied to the local load (through the inverter), 700 W is fed into the grid (through the inverter), and 200 W is charged to its own battery (DC side, not through the inverter), and the inverter target power is -1000 W.

[0371] PCS3 is a surplus device, Pnet(3) = 700 W. Its PV output of 1200 W, of which 500 W is supplied to the local load (through the inverter), 500 W is fed into the grid (through the inverter), and 200 W is charged to the battery (DC side, not through the inverter), and the inverter target power is - 1000 W.

[0372] 6. Power balance check (final period).

[0373] The input of PCS1 is 600W battery discharge, and the output is 200W load plus 400W feed, totaling 600W, power balance. The input of PCS2 is 1200W photovoltaic, and the output is 300W load plus 700W feed plus 200W charging, totaling 1200W, power balance. The input of PCS3 is 1200W photovoltaic, and the output is 500W load plus 500W feed plus 200W charging, totaling 1200W, power balance. The total grid feed-in is 400+700+500=1600W, which meets the requirements.

[0374] Inverter capacity check: the load of 200W of PCS1 plus the feed of 400W equals 600W, which does not exceed the rated power of the inverter 1000W. The load of 300W of PCS2 plus the feed of 700W equals 1000W, which does not exceed the rated power of the inverter 1000W. The feed of 500W of PCS3 plus the feed of 500W equals 1000W, which does not exceed the rated power of the inverter 1 000W. All meet the capacity constraints.

[0375] 7. Summary.

[0376] First, each step cycle executes step S1140 to issue instructions, P InvTarget Dynamic update with increasing PV output, issued once per cycle.

[0377] Second, the total grid feed-in power remains constant at 1600W, and the sum of the feeds of PCS1, PCS2 and PCS3 is 400+700+500=1600W, which is always equal to MaxGridDischargePower.

[0378] Third, the step adjustment is executed in two stages. In stage one (periods 1 to 4), the PV output of PCS2 and PCS3 is increased synchronously, and the newly added power is preferentially increased to the feed, and the battery discharge of PCS1 is reduced synchronously. In stage two (periods 5 to 8), PCS2 and PCS3 both reach the upper limit of the feed, the newly added power is transferred to photovoltaic DC charging, and the battery discharge of PCS1 remains unchanged until both devices reach the PV upper limit.

[0379] Fourth, PV power goes to full. PCS2's PV increases from 900W to 1200W, increases by 300W, reaches the upper limit of MaxPvPower(2), the feed increases from 600W to 700W, increases by 100W, reaches the upper limit of the inverter feed, and the charge increases from 0 to 200W. PCS3's PV increases from 800W to 1200W, increases by 300W, reaches the upper limit of MaxPVPower(3), the feed increases from 300W to 500W, increases by 200W, reaches the upper limit of the inverter feed, and the charge increases from 0W to 200W. The newly added PV power increases the feed first, and when the feed is saturated, it turns to photovoltaic DC charging.

[0380] Fifth, the battery discharge is gradually reduced, and the PCS1 battery discharge is gradually reduced from the initial 700W to the final 400W, reduced by 300W, effectively reducing the battery discharge depth and prolonging the battery life.

[0381] Sixth, the SOC balancing effect is good, the high SOC device (PCS1, 80%) undertakes the battery discharge, the medium SOC device (PCS2, 60% and PCS3, 40%) undertakes the photovoltaic feed and photovoltaic DC charging, and promotes the battery SOC balancing.

[0382] Summary: The two examples of Example Two respectively demonstrate the discharge control in the photovoltaic sufficient (P surplus ≥ MaxGridDischargePower) and photovoltaic insufficient (P surplus < MaxGridDischargePower) scenarios. When the photovoltaic is sufficient, the EMS allocates the feed power in descending order of P net , and in descending order of SOC when they are equal, preferentially using the photovoltaic of the high SOC device to discharge to the grid without battery supplement; the surplus power is used for BMS charging and mutual aid output in turn. When the photovoltaic is insufficient, all photovoltaic surplus is preferentially used for feed, and the remaining gap is supplemented by dischargeable devices in descending order of SOC, with high SOC devices preferentially discharging; at the same time, the photovoltaic output is increased through step adjustment to reduce the battery discharge demand, and when the feed channel is saturated, the newly added output is turned to BMS charging. In both scenarios, the total feed power is accurately equal to MaxGridDischargePower, and the balancing principle of high SOC preferential discharge is followed.

[0383] Example Three: Standby period (internal mutual aid, no grid exchange).

[0384] 1. System configuration.

[0385] In this embodiment, PCS1 has photovoltaic access, the SOC is 80%, the local load power is 100W, the maximum allowed charging power of the battery is 1500W, the actual power of the photovoltaic is 2000W, and the net exchange power is 400W, which is a surplus device.

[0386] PCS2 has PV access, SOC is 60%, local load power is 200W, maximum allowed charging power of battery is 1000W, actual PV power is 500W, net exchange power is -700W, it is a deficit device.

[0387] PCS3 has no PV access, SOC is 40%, local load power is 50W, maximum allowed charging power of battery is 2000W, actual PV power is 0W, net exchange power is -2050W, it is a deficit device.

[0388] Set standby mode, system does not exchange power with grid (no power taking, no power feeding). Total surplus power P surplus = 400W, total deficit power P deficit = 700 + 2050 = 2750W. The rated power of inverters is 1000W, assuming that the PV and battery capacity is sufficient, but the PV capacity of PCS1 has reached the upper limit MaxPvPower(1) = 2000W.

[0389] 2. Execution process.

[0390] According to step S1310, perform mutual aid power distribution. PCS1 uses its surplus power 400W for internal mutual aid (supplying deficit devices). Deficit devices are sorted by SOC from low to high, that is, PCS3 (SOC = 40%) is preferred to PCS2 (SOC = 60%).

[0391] According to steps S1410 to S1440, initialize R mutual3 = 400W. For PCS3, its mutual aid power P mutual (3) = min(|P net (3)|, R mutual3 , P invmax (3) - P Load (3)) = min(2050, 400, 1000) = 400W, update R mutual3 = 400 - 400 = 0W. For PCS2, since R mutual3 has been 0, its mutual aid power is 0W. The allocation result is that PCS3 obtains all 400W mutual aid, and PCS2 does not obtain mutual aid.

[0392] The physical flow direction of mutual aid power is: PCS1 feeds the net surplus power after deducting local load and its own BMS charging into the internal AC bus of the system through the inverter, and this 400W power is transmitted through the AC line and is absorbed by the inverter of PCS3 to supplement its charging deficit.

[0393] According to step S1320, handle power imbalance. P surplus is 400W which is less than Pdeficit of 2750W, meeting the standby constraint (no feeding to the grid). Since P deficit - P surplus = 2750 - 400 = 2350W, greater than the margin of 50W, the EMS attempts to step up the power regulation value P adj (1) of PCS1 to boost its photovoltaic output and increase P surplu s.

[0394] The step regulation determines that: PCS1 current P ActPV (1) = 2000W, MaxPvPower(1) = 2000W, P ActPV (1) + P adj (1) ≥ MaxPvPower(1), PCS1 has reached the photovoltaic physical upper limit, meeting the device exit condition of the standby period (condition one), PCS1 cannot continue to increase the output, and the step regulation is exited.

[0395] The step regulation is stopped, and the mutual aid is insufficient. Since the mutual aid is insufficient and PCS1 has reached the PV upper limit, the 200W local load of PCS2 is supplied by the discharge of its own battery (the standby period allows internal battery discharge to carry the load). The charge deficiency of PCS3 is still 2050 - 400 = 1650W, which cannot be made up, and the system maintains the current state.

[0396] According to the instructions issued in steps S1330 to S1350.

[0397] The inverter target power P InvTarget (1) of PCS1 is -P Load (1) - P mutual_out (1) = -100 - 400 = -500W, meaning that the inverter discharges 500W (load 100W + mutual aid 400W), which has reached the PV upper limit.

[0398] The inverter target power P InvTarget (2) of PCS2 is -P Load (2) + P mutual_in (2) = -200 + 0 = -200W, meaning that the inverter discharges 200W (battery discharge to carry the load).

[0399] The inverter target power P InvTarget (3) of PCS3 is -P Load (3) + P mutual_in (3) = -50 + 400 = +350W, meaning that the inverter charges 350W (mutual aid 400W charging minus load 50W).

[0400] P adj is updated to: P adj(1)=50W, P adj (2)=0W, P adj (3)=0W. EMS will update P adj (i) and P InvTarget (i) of each device to each PCS.

[0401] 3. Power balance check.

[0402] The input of PCS1 is photovoltaic 2000W, the output is photovoltaic direct current charging 1500W plus load 100W plus mutual aid 400W, totaling 2000W, and the power is balanced.

[0403] The input of PCS2 is photovoltaic 500W plus battery discharge 200W, and the output is load 200W, but there are 300W of excess that cannot be output, so photovoltaic power limiting is required, the actual input is 200W, and the output is 200W.

[0404] The input of PCS3 is mutual aid 400W, and the output is load 50W plus battery charging 350W, totaling 400W, and the power is balanced.

[0405] The power balance check result is that the input of PCS1 is 2000W, equal to the output 2000W, which satisfies the balance. The actual input of PCS2 is 200W, equal to the output 200W, which satisfies the balance. The input of PCS3 is 400W, equal to the output 400W, which satisfies the balance.

[0406] 4. Conclusion.

[0407] In the standby period, the EMS distributes the surplus power through centralized mutual aid, and transfers the surplus power to the devices with insufficient power according to the SOC from low to high priority. The device with low SOC obtains mutual aid first, which effectively promotes the SOC balance of the battery pack. In this example, PCS3 with the lowest SOC obtains all 400W of mutual aid, while PCS2 with higher SOC does not obtain mutual aid, which reflects the priority rule. The device with insufficient power (PCS2) is supplied by its own battery discharge to the local load, and the part of the charging demand that cannot be met is cut off when the mutual aid is insufficient. Step adjustment can be used to further increase the photovoltaic output and increase the mutual aid power when the light intensity increases and the device does not reach the PV upper limit, but in this example, PCS1 has reached the MaxPvPower(1)=2000W upper limit, and step adjustment cannot continue. During the entire process, the system has no power exchange with the grid, meets the standby constraint, and does not require additional hardware. The control logic is simple and reliable, and is suitable for self-balancing operation of a household energy storage system.

[0408] The embodiment of the application also provides an energy storage system. The energy storage system comprises a plurality of energy storage converters and an energy management system.

[0409] Any one of the energy storage converters is electrically connected with the photovoltaic module and the battery respectively, and all the energy storage converters are electrically connected with the power grid. Specifically, each energy storage converter is provided with a direct-current side power control unit, an alternating-current side power control unit, a data acquisition unit and a communication unit.

[0410] The direct-current side power control unit: realizes MPPT maximum power point tracking control of the photovoltaic module and charge-discharge power control of the battery, can receive photovoltaic target power instructions issued by the energy management system, and adjusts the actual output power of the photovoltaic module; meanwhile, the direct-current side power control unit is constrained by the battery management system (BMS) and executes the maximum allowable charge-discharge power limit of the battery.

[0411] The alternating-current side power control unit: realizes power regulation of the alternating-current side of the inverter, can receive inverter target power instructions issued by the energy management system, completes local load power supply, power grid power interaction and power transmission between units; the alternating-current side operation is constrained by the rated power of the inverter to avoid hardware overload.

[0412] The data acquisition unit: acquires real-time local operation parameters, including photovoltaic actual power, battery state of charge (SOC), local load power, maximum allowable charge-discharge power of the battery, rated power of the inverter, upper limit of photovoltaic maximum output, equipment communication state and the like, and provides data support for control decisions of the energy management system.

[0413] The communication unit: establishes real-time communication with the energy management system, reports local operation parameters, receives and analyzes control instructions issued by the energy management system.

[0414] The energy management system is electrically connected with each energy storage converter. Specifically, the energy management system is the core control unit of the entire energy storage system, including a communication unit, a data processing unit and a control instruction generation unit, and is used to execute the full-process steps of the power regulation method of the energy storage system.

[0415] The communication unit: establishes bidirectional real-time communication with all energy storage converters, periodically receives operation parameters reported by each energy storage converter, and simultaneously issues control instructions generated to the corresponding energy storage converter.

[0416] The data processing unit: executes system-level data processing and control logic, including: based on the operation parameters of each device, calculating the net exchange power of each energy storage converter, the total surplus power and the total deficiency power of the system, judging the current operation period (charging period, discharging period and standby period) of the system; according to the control rules of the corresponding period, executing power distribution, mutual aid distribution and step adjustment logic, and calculating the corresponding photovoltaic target power and inverter target power of each energy storage converter; executing device exit condition judgment, hardware constraint limiting and SOC priority sorting and the like auxiliary logic to ensure the rationality and safety of the control instructions.

[0417] The control instruction generation unit packs the photovoltaic target power and the inverter target power calculated by the data processing unit into a standard control message, and sends the standard control message to the corresponding energy storage converter through the communication unit to form a closed-loop iterative control.

[0418] The energy storage system provided by the embodiments of the present application can flexibly schedule the power flow among the photovoltaic power, the battery and the power grid under different operation scenarios (charging, discharging and standby) through centralized coordination control of the multiple energy storage converters by the energy management system. The system not only realizes the maximized utilization of the photovoltaic energy and the accurate control of the interactive power of the power grid, but also effectively balances the state of charge of the batteries of the energy storage converters through the SOC priority-based allocation strategy, prolongs the service life of the battery pack, and improves the overall operation efficiency and reliability of the energy storage system.

[0419] As shown in Figure 8 The energy management system 1600 includes at least one processor 1610 and a memory 1620. The memory 1620 can be built-in or external to the energy management system 1600, and can also be a remote memory connected to the energy management system 1600 through a network.

[0420] The memory 1620 is a non-volatile computer readable storage medium, which can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory 1620 can include a program storage area and a data storage area. The program storage area can store an operating system and application programs required by at least one function; the data storage area can store data created by the terminal during use, etc. In addition, the memory 1620 can include a high-speed random access memory, and can also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state memory device. In some embodiments, the memory 1620 can optionally include a memory remotely arranged with respect to the processor 1610, which can be connected to the terminal through a network. Examples of the above network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0421] The processor 1610 executes various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 1620 and calling data stored in the memory 1620, thereby monitoring the terminal as a whole, such as implementing the power regulation method of the energy storage system and the energy storage system in any embodiment of the present application.

[0422] The processor 1610 can be one or more, Figure 8The processor 1610 and the memory 1620 can be connected through a bus or other means. The processor 1610 can include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, or the like. The processor 1610 can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0423] The above merely illustrates the embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

[0424] The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; the technical features of the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power regulation method for an energy storage system, characterized in that, The energy storage system includes multiple energy storage converters, each of which is electrically connected to a photovoltaic module and a battery, and all of the energy storage converters are electrically connected to the power grid. The power regulation method includes: Determine an effective energy storage converter, wherein the effective energy storage converter is an energy storage converter that receives a voltage greater than a preset voltage threshold from the photovoltaic module; Determine the step feedback ratio corresponding to each effective energy storage converter, wherein the step feedback ratio characterizes the tracking accuracy of the actual photovoltaic power of the effective energy storage converter to the photovoltaic target power in the current control cycle; Determine the current runtime segment, wherein the runtime segment includes a charging segment, a discharging segment, and a standby segment; When the operating period is the charging period or the standby period, the net exchange power corresponding to each energy storage converter is determined based on the difference between the actual photovoltaic power, load power, and maximum allowable charging power of the battery corresponding to each energy storage converter in the current control cycle; the total surplus power is determined based on the sum of net exchange powers greater than 0; the total deficit power is determined based on the sum of net exchange powers less than 0; the target deficit value is determined based on the difference between the total deficit power and the total surplus power, and a step adjustment step is executed based on the target deficit value. When the operating period is the discharge period, the net exchange power corresponding to each energy storage converter is determined based on the difference between the actual photovoltaic power and the load power corresponding to each energy storage converter in the current control cycle; the total surplus power is determined based on the sum of net exchange powers greater than 0; the total deficit power is determined based on the sum of net exchange powers less than 0; the total surplus power is allocated sequentially for grid feeding and battery charging, and the remaining total mutual assistance power is calculated after allocation; when the total mutual assistance power is less than the total deficit power, the target deficit value is determined based on the difference between the total deficit power and the total mutual assistance power, and the step adjustment steps are executed based on the target deficit value; The step adjustment step includes: performing differentiated adjustment on the power adjustment value that matches the adjustment direction and adapts to the equipment operating state, based on the target gap value and the adjustment direction it represents, as well as the net exchange power and step feedback ratio of each effective energy storage converter and the equipment operating state of each effective energy storage converter. The target photovoltaic power for each energy storage converter in the current control cycle is determined by the sum of the load power, the maximum allowable charging power of the battery, and the power adjustment value, and the minimum value among the maximum photovoltaic power corresponding to each energy storage converter.

2. The power regulation method according to claim 1, characterized in that, The step of performing differentiated adjustment on the power adjustment value, matching the adjustment direction and adapting to the equipment operating state, based on the target gap value and its represented adjustment direction, and the net exchange power and step feedback ratio of each effective energy storage converter, respectively, representing the equipment operating state of each effective energy storage converter, includes: According to the sorting of the state of charge values ​​of the batteries corresponding to each effective energy storage converter from low to high, each effective energy storage converter is set as the i-th effective energy storage converter. When the target gap value is less than 0, the power adjustment value corresponding to the i-th effective energy storage converter is updated according to the maximum value between the first difference and 0, and the target gap value is updated according to the sum of the target gap value and the preset downward adjustment threshold, wherein the first difference is the difference between the power adjustment value corresponding to the i-th effective energy storage converter and the downward adjustment threshold. When the target gap value is greater than 0, the power adjustment value is adjusted to adapt to the device operating state by using the lowering step threshold or the preset upper step threshold, and the target gap value is updated according to the lowering step threshold or the upper step threshold. When the upper step threshold is used, the target gap value is updated according to the difference between the target gap value and the upper step threshold. When the target gap value is equal to 0, the power adjustment value corresponding to the i-th effective energy storage converter remains unchanged.

3. The power regulation method according to claim 2, characterized in that, The step of applying the lowering step threshold or a preset upper step threshold to perform differentiated adjustment of the power adjustment value to adapt to the operating state of the equipment, and updating the target gap value according to the lowering step threshold or the upper step threshold, includes: When the net switching power corresponding to the i-th effective energy storage converter is less than 0, the power adjustment value corresponding to the i-th effective energy storage converter is updated according to the maximum value between the first difference and 0, and the target gap value is updated according to the sum of the target gap value and the downward adjustment step threshold. When the net switching power corresponding to the i-th effective energy storage converter is greater than or equal to 0, the following steps are performed: If the step feedback ratio is greater than or equal to a preset upper limit threshold, then the upward step threshold is updated according to the minimum value between the target gap value and the upward step threshold; the power adjustment value corresponding to the i-th effective energy storage converter is updated according to the minimum value between the first sum and the maximum photovoltaic power corresponding to the i-th effective energy storage converter; and the target gap value is updated according to the difference between the target gap value and the upward step threshold, wherein the first sum is the sum of the power adjustment value corresponding to the i-th effective energy storage converter and the upward step threshold; If the step feedback ratio is less than the preset lower threshold, then the power adjustment value corresponding to the i-th effective energy storage converter is updated according to the maximum value between the first difference and 0, and the target gap value is updated according to the sum of the target gap value and the lower step threshold. If the step feedback ratio is greater than or equal to the preset lower threshold and less than the preset upper threshold, then the power adjustment value remains unchanged.

4. The power regulation method according to claim 2 or 3, characterized in that, The method further includes: When the operating period is the charging period or the standby period, if the i-th effective energy storage converter satisfies one of the following conditions one, two, and three, the power adjustment value corresponding to the i-th effective energy storage converter remains unchanged. When the operating period is the discharge period, if the i-th effective energy storage converter satisfies one of the following conditions one, three, and four, then the power adjustment value corresponding to the i-th effective energy storage converter remains unchanged. Among them, the first condition is that the sum of the actual photovoltaic power and the power adjustment value corresponding to the i-th effective energy storage converter is greater than the maximum photovoltaic power; the second condition is that the battery corresponding to the i-th effective energy storage converter is fully charged and the mutual assistance output power of the inverter in the i-th effective energy storage converter is equal to its maximum power that can be used for mutual assistance; the third condition is that the i-th effective energy storage converter experiences a communication abnormality or response timeout; and the fourth condition is that the battery corresponding to the i-th effective energy storage converter is fully charged and the actual output power of the inverter in the i-th effective energy storage converter is equal to its rated power.

5. The power regulation method according to claim 3, characterized in that, When the running period is the charging period, the step adjustment step further includes: If the net switching power corresponding to the i-th effective energy storage converter is greater than the rated power of the inverter in the i-th effective energy storage converter, then the step feedback ratio is set to be less than the preset lower threshold.

6. The power regulation method according to claim 1, characterized in that, The method further includes: When the running segment is the charging period, after performing the step adjustment based on the target gap value, the following steps are also performed: Based on the state of charge values ​​of the batteries corresponding to all the deficit devices, sorted from low to high, the total surplus power is allocated to each deficit device in sequence, and the mutual assistance power corresponding to each deficit device is determined. The deficit device is an energy storage converter with a net exchange power of less than 0. If the target gap value is greater than 0, then the power grid is used to supplement the power of each of the missing devices to determine the power grid supplementation power corresponding to each of the missing devices, until the total available power grid charging power is 0 or all missing devices have been allocated. Set the grid power supply for energy storage converters other than those with insufficient capacity to 0. Based on the sum of the mutual assistance power and the grid supplementary power corresponding to each energy storage converter, and the difference between the sum and the load power, the target inverter power corresponding to each energy storage converter in the current control cycle is determined.

7. The power regulation method according to claim 6, characterized in that, The step of allocating the total surplus power to each of the deficit devices in order of their state of charge values ​​from low to high includes: Initialize the first remaining mutual aid power to be equal to the total surplus power; According to the sorting of the state of charge values ​​of the batteries corresponding to each missing device from low to high, each missing device is set as the j-th missing device. The mutual assistance power corresponding to the j-th slack device is determined based on the minimum value among the difference between the rated power and the load power of the inverter corresponding to the j-th slack device, the absolute value of the net exchange power, and the first remaining mutual assistance power. The first remaining mutual assistance power is updated based on the difference between the first remaining mutual assistance power and the mutual assistance power corresponding to the j-th deficit device. The remaining deficit power corresponding to the j-th deficit device is determined based on the difference between the absolute value of the net exchange power corresponding to the j-th deficit device and the mutual assistance power. The remaining available capacity of the inverter in the j-th slack device is determined based on the difference between the rated power, load power, and mutual assistance power of the inverter in the j-th slack device, and the maximum value among 0.

8. The power regulation method according to claim 7, characterized in that, The process of replenishing power to each of the deficient devices through the power grid includes: The total grid charging power is determined based on the minimum value between the target gap value and the preset maximum grid charging power. The grid replenishment power corresponding to the j-th defective device is determined based on the minimum value among the remaining defective power corresponding to the j-th defective device, the total grid charging power, and the remaining available capacity of the inverter in the j-th defective device. The total power of the grid charging is updated based on the difference between the total power of the grid charging and the power of the grid supplementation corresponding to the j-th deficient device.

9. The power regulation method according to claim 1, characterized in that, The step of allocating the total surplus power sequentially for grid power supply and battery charging, and calculating the remaining total mutual assistance power after allocation, includes: The surplus equipment is sorted as follows: the first sorting condition is based on the net exchange power from high to low, and when the net exchange power is equal, the second sorting condition is based on the state of charge value of the battery from high to low; according to the order after sorting, each surplus equipment is set as the kth surplus equipment, wherein the surplus equipment is an energy storage converter with a net exchange power greater than 0. When the total surplus power is greater than or equal to the preset maximum grid power, the total surplus power is allocated for grid power supply to determine the power supply corresponding to the k-th surplus device. If the k-th surplus device has residual power after allocation, the residual power of the k-th surplus device is used for charging the battery corresponding to the k-th surplus device. The remaining power after charging is the mutual assistance power corresponding to the k-th surplus device. When the total surplus power is less than the maximum grid feed power, all of the total surplus power is used for grid feed to determine the photovoltaic feed power corresponding to the k-th surplus device. The remaining feed gap is determined based on the difference between the maximum grid feed power and the total surplus power, and the remaining feed gap is supplemented by discharging the battery corresponding to the dischargeable device to determine the feed power corresponding to the k-th surplus device. This process continues until the remaining feed gap is 0 or all dischargeable devices have been allocated. Here, the mutual assistance power corresponding to the k-th surplus device is 0, and the dischargeable device is the energy storage converter whose corresponding battery is allowed to discharge. The total mutual assistance power is determined by summing the mutual assistance power of all surplus equipment with mutual assistance power greater than 0.

10. The power regulation method according to claim 9, characterized in that, When the total surplus power is greater than or equal to the preset maximum grid feed power, the total surplus power is allocated for grid feed to determine the feed power corresponding to the k-th surplus device. If the k-th surplus device has remaining power after allocation, the remaining power of the k-th surplus device is used for charging the battery corresponding to the k-th surplus device. The remaining power after charging is the mutual assistance power corresponding to the k-th surplus device, including: The initial target power of the first power supply is equal to the maximum power supply power of the grid. When the first power supply target power is greater than 0, the power supply power corresponding to the kth surplus device is determined based on the minimum value among the difference between the rated power of the inverter and the load power corresponding to the kth surplus device, the net switching power, and the first power supply target power, and the first power supply target power is updated based on the difference between the first power supply target power and the power supply power corresponding to the kth surplus device. When the first power supply target power is less than or equal to 0, the power supply corresponding to the kth surplus device is set to 0; The remaining power corresponding to the kth surplus device is determined based on the difference between the net switching power and the feed power of the kth surplus device. When the remaining power corresponding to the k-th surplus device is greater than 0, the charging power of the battery corresponding to the k-th surplus device is determined based on the minimum value between the remaining power corresponding to the k-th surplus device and the maximum allowable charging power of the battery. The mutual assistance power corresponding to the k-th surplus device is determined based on the difference between the remaining power corresponding to the k-th surplus device and the charging power of the battery corresponding to the k-th surplus device.

11. The power regulation method according to claim 9, characterized in that, The step of using all the total surplus power for grid feeding to determine the photovoltaic feeding power corresponding to the k-th surplus device, determining the remaining feeding gap based on the difference between the maximum grid feeding power and the total surplus power, and supplementing the remaining feeding gap by discharging the batteries corresponding to the dischargeable devices to determine the feeding power corresponding to the k-th surplus device includes: The initial second feed target power is equal to the total surplus power; When the second power supply target power is greater than 0, the photovoltaic power supply corresponding to the kth surplus device is determined based on the minimum value among the difference between the rated power of the inverter and the load power corresponding to the kth surplus device, the net exchange power, and the second power supply target power. The second power supply target power is then updated based on the difference between the second power supply target power and the photovoltaic power supply corresponding to the kth surplus device. When the second power supply target power is equal to 0, the remaining power supply gap power is determined based on the difference between the maximum power supply to the grid and the total surplus power. The remaining usable capacity of the inverter corresponding to the k-th surplus device is determined by the maximum value among the differences between the rated capacity of the inverter corresponding to the k-th surplus device, the feed power, and the load power, and 0. The battery discharge power corresponding to the k-th surplus device is determined by the minimum value among the remaining feed power gap power, the maximum allowable discharge power of the battery corresponding to the k-th surplus device, and the remaining usable capacity of the inverter. The feed power corresponding to the k-th surplus device is determined by the sum of the photovoltaic feed power and the battery discharge power corresponding to the k-th surplus device, and the remaining feed power gap power is updated based on the difference between the remaining feed power gap power and the battery discharge power corresponding to the k-th surplus device.

12. The power regulation method according to any one of claims 9-11, characterized in that, The method further includes: When the running segment is the discharge period, after performing the step of calculating the remaining total mutual assistance power after the allocation is completed, the following steps are also performed: Based on the total mutual assistance power, determine the mutual assistance output power corresponding to each surplus device; The second remaining mutual aid power is determined based on the minimum value between the total mutual aid power and the total deficit power; The second remaining mutual aid power is allocated to all the deficient equipment to determine the mutual aid input power corresponding to each deficient equipment, until the second remaining mutual aid power is 0 or all the deficient equipment has been allocated. Based on the differences between the mutual input power and mutual output power, feed power and load power of each energy storage converter, the target inverter power of each energy storage converter in the current control cycle is determined.

13. The power regulation method according to claim 12, characterized in that, The step of determining the mutual assistance output power corresponding to each surplus device based on the total mutual assistance power includes: The mutual aid output power corresponding to the kth surplus device is determined based on the minimum value among the difference between the rated power of the inverter corresponding to the kth surplus device, the load power, and the feed power, and the mutual aid power corresponding to the kth surplus device.

14. The power regulation method according to claim 12, characterized in that, The step of allocating the second remaining mutual aid power to all deficit devices to determine the mutual aid input power corresponding to each deficit device includes: According to the sorting of the state of charge values ​​of the batteries corresponding to each missing device from low to high, each missing device is designated as the m-th missing device. The mutual assistance input power corresponding to the m-th defective device is determined based on the difference between the rated power of the inverter and the load power, the absolute value of the net exchange power, the minimum value among the second remaining mutual assistance power and the maximum allowable charging power of the battery. The second remaining mutual aid power is updated based on the difference between the second remaining mutual aid power and the mutual aid input power corresponding to the m-th deficit device.

15. The power regulation method according to claim 2 or 3, characterized in that, When the running period is the standby period, the step adjustment step further includes: When the total surplus power is less than the difference between the total deficit power and the preset threshold, the power adjustment value corresponding to the i-th effective energy storage converter is increased; When the total surplus power is greater than the sum of the total deficit power and the preset threshold, the power adjustment value corresponding to the i-th effective energy storage converter is reduced.

16. The power regulation method according to claim 1, characterized in that, The method further includes: When the running period is the standby period, before performing the step adjustment step based on the target gap value, the following steps are also performed: The total surplus power is allocated to all deficit devices to determine the mutual assistance input power corresponding to each deficit device; When the total surplus power is greater than the total deficit power, the excess power is determined based on the difference between the total surplus power and the total deficit power, and the excess power is reduced to 0 by decreasing the power adjustment value and / or limiting the output power of the photovoltaic module; The target inverter power for each device with a shortage is determined based on the difference between the input power and the load power of the device with the shortage. The target inverter power for each surplus device is determined based on the difference between the negative net switching power of each surplus device and the load power. Based on the load power corresponding to each balancing device, the target inverter power corresponding to each balancing device is determined, wherein the balancing device is an energy storage converter with a net switching power of 0.

17. The power regulation method according to claim 16, characterized in that, The step of allocating the total surplus power to all deficit devices to determine the mutual assistance input power corresponding to each deficit device includes: The third remaining mutual aid power is initialized to be equal to the total surplus power; According to the sorting of the state of charge values ​​of the batteries corresponding to each missing device from low to high, each missing device is designated as the nth missing device. The mutual assistance power corresponding to the nth slack device is determined based on the minimum value among the difference between the rated power and the load power of the inverter corresponding to the nth slack device, the absolute value of the net exchange power, and the third remaining mutual assistance power. The third remaining mutual aid power is updated based on the difference between the third remaining mutual aid power and the mutual aid power corresponding to the nth deficit device.

18. The power regulation method according to claim 16, characterized in that, The step of reducing the excess power to 0 by decreasing the power adjustment value and / or limiting the output power of the photovoltaic module includes: According to the order of the actual photovoltaic power corresponding to each effective surplus device from high to low, each effective surplus device is set as the a-th effective surplus device, wherein the effective surplus device is an effective energy storage converter with a net exchange power greater than 0. Reduce the power adjustment value corresponding to the a-th effective surplus device; If the excess power is still greater than 0 after the power adjustment values ​​of all available surplus equipment have been reduced to 0, then the output power of the photovoltaic module corresponding to at least one available surplus equipment shall be limited so that the excess power is reduced to 0.

19. The power regulation method according to claim 1, characterized in that, Determining the step feedback ratio corresponding to each effective energy storage converter includes: When the photovoltaic target power corresponding to the b-th effective energy storage converter is less than the photovoltaic maximum power corresponding to the b-th effective energy storage converter, the step feedback ratio corresponding to the b-th effective energy storage converter is the ratio of the actual photovoltaic power corresponding to the b-th effective energy storage converter to the photovoltaic target power, wherein the b-th effective energy storage converter is any effective energy storage converter; When the photovoltaic target power corresponding to the b-th effective energy storage converter is 0, the step feedback ratio corresponding to the b-th effective energy storage converter is configured to 1; When the photovoltaic target power corresponding to the b-th effective energy storage converter is greater than or equal to the maximum photovoltaic power, and the actual photovoltaic power corresponding to the b-th effective energy storage converter is equal to the photovoltaic target power, the step feedback ratio corresponding to the b-th effective energy storage converter is configured to be greater than a preset lower threshold and less than a preset upper threshold.

20. An energy storage system, characterized in that, include: Multiple energy storage converters, each of which is electrically connected to a photovoltaic module and a battery, and all of which are electrically connected to the power grid; And an energy management system, electrically connected to each of the energy storage converters, including: at least one processor and a memory; The memory is coupled to the processor and is used to store instructions or programs that, when executed by the at least one processor, cause the at least one processor to perform the power regulation method of the energy storage system as described in any one of claims 1-19.

Images