Charging and discharging control method and related device

Abstract

The invention provides a charging and discharging control method and a related device, and relates to the field of energy storage. According to the method, the power of each battery is confirmed according to the total power change amount and the power change proportion of the battery, and in the power adjusting process, the mode of distributing the total power change amount to each battery is directly adopted, so that the actual charging and discharging power of the battery does not need to be used; the problem of power oscillation caused by inaccurate actual charging and discharging power collection of the battery is avoided, so that power adjustment is smoother, the accuracy of SOC equalization operation is improved, and the method is suitable for a rapid dynamic closed-loop response scene. Besides, the power change ratio of the battery is determined based on the charge state and the rated capacity of the battery, and the battery capacity can be considered during battery power distribution, so that each converter in the optical storage system can be connected with batteries with different capacities, and the batteries with different capacities can be mixed for use.

Description

Technical Field

[0001] This application relates to the field of energy storage, and more specifically, to a charging and discharging control method and related devices. Background Technology

[0002] In a typical photovoltaic-storage system, each inverter connects to a group of batteries. In grid-connected scenarios, if the State of Charge (SOC) of the batteries connected to one or more inverters is unbalanced, it may affect the stability of the entire system. Summary of the Invention

[0003] In view of this, this application provides a charge and discharge control method and related apparatus to achieve SOC balancing operation of a battery.

[0004] To solve the above-mentioned technical problems, this application adopts the following technical solution:

[0005] In a first aspect, this application discloses a charging and discharging control method, comprising:

[0006] The total power change of each battery in the photovoltaic-storage system is obtained; wherein, the photovoltaic-storage system further includes multiple inverters, each inverter being connected to at least one battery; each battery includes at least one cell; the total power change is the total change in charging power or the total change in discharging power of each battery;

[0007] The percentage of power change of the battery is determined based on the battery's state of charge and rated capacity; the percentage of power change is used to indicate the percentage of charging or discharging of the battery.

[0008] The power of each battery is determined based on the total power change and the percentage of power change of the battery; the power includes charging power or discharging power.

[0009] The power of the battery is used to control the charging or discharging of the battery.

[0010] Optionally, determining the discharge percentage of the battery based on its state of charge and rated capacity includes:

[0011] The remaining energy of the battery is the product of its state of charge and its rated capacity.

[0012] Calculate the ratio of the remaining energy of the battery to the total remaining energy, and use the ratio as the discharge percentage of the battery; the total remaining energy is the sum of the remaining energy of all batteries.

[0013] Optionally, determining the discharge percentage of the battery based on its state of charge and rated capacity includes:

[0014] Calculate the difference between the rated capacity of the battery and the remaining energy of the battery;

[0015] The ratio of the difference to the total remaining energy is used as the charging percentage of the battery.

[0016] Optionally, the total power change is the total charging power change. Based on the total power change and the percentage of power change in each battery, the power of each battery is determined, including:

[0017] When it is necessary to increase the battery charging power, for each battery, the product of the total change in charging power and the charging percentage of the battery is calculated to obtain the power change of the battery in the current cycle.

[0018] The sum of the battery's charging power in the previous cycle and the battery's power change in the current cycle is taken as the battery's charging power in the current cycle.

[0019] Optionally, determining the power of each battery based on the total power change and the percentage of power change of the battery further includes:

[0020] When it is necessary to reduce the battery charging power, obtain the total charging power of all batteries;

[0021] If the total charging power of all batteries is greater than or equal to the total change in charging power, then for each battery, the product of the total change in charging power and the charging percentage of the battery is calculated to obtain the power change of the battery in the current cycle.

[0022] When the charging and discharging states of all batteries do not need to be consistent, the difference between the charging power of the battery in the previous cycle and the power change of the battery in the current cycle is taken as the charging power of the battery in the current cycle.

[0023] When the charging and discharging states of all batteries need to remain consistent, if the charging power of a battery in the previous cycle is greater than the power change of the battery in the current cycle, the difference between the charging power of the battery in the previous cycle and the power change of the battery in the current cycle shall be taken as the charging power of the battery in the current cycle; if the charging power of a battery in the previous cycle is less than or equal to the power change of the battery in the current cycle, the charging power of the battery in the current cycle shall be set to zero.

[0024] Optionally, determining the power of each battery based on the total power change and the percentage of power change of the battery further includes:

[0025] If the total charging power of all batteries is less than the total change in charging power, calculate the difference between the total change in charging power and the total charging power to obtain the power difference value;

[0026] The product of the battery's discharge percentage and the power difference is taken as the battery's discharge power in the current cycle.

[0027] Optionally, the total power change is the total discharge power change. Based on the total power change and the percentage of power change in each battery, the power of each battery is determined, including:

[0028] When it is necessary to increase the battery discharge power, for each battery, the product of the total change in discharge power and the discharge percentage of the battery is calculated to obtain the power change of the battery in the current cycle.

[0029] The sum of the battery's discharge power in the previous cycle and the battery's power change in the current cycle is taken as the battery's discharge power in the current cycle.

[0030] Optionally, determining the power of each battery based on the total power change and the percentage of power change of the battery further includes:

[0031] When it is necessary to reduce the battery discharge power, obtain the total discharge power of all batteries;

[0032] If the total discharge power of all batteries is greater than or equal to the total change in discharge power, then for each battery, the product of the total change in discharge power and the discharge percentage of the battery is calculated to obtain the power change of the battery in the current cycle.

[0033] When the charging and discharging states of all batteries do not need to be consistent, the difference between the discharge power of the battery in the previous cycle and the power change of the battery in the current cycle is taken as the discharge power of the battery in the current cycle.

[0034] When the charging and discharging states of all batteries need to remain consistent, if the discharge power of a battery in the previous cycle is greater than the power change in the current cycle, the difference between the discharge power of the battery in the previous cycle and the power change in the current cycle shall be taken as the discharge power of the battery in the current cycle; if the discharge power of a battery in the previous cycle is less than or equal to the power change in the current cycle, the discharge power of the battery in the current cycle shall be set to zero.

[0035] Optionally, determining the power of each battery based on the total power change and the percentage of power change of the battery further includes:

[0036] If the total discharge power of all batteries is less than the total change in discharge power, calculate the difference between the total change in discharge power and the total discharge power to obtain the power difference value;

[0037] The product of the battery's charging percentage and the power difference is taken as the battery's charging power in the current cycle.

[0038] Optionally, the charge / discharge control method further includes:

[0039] Under the condition that the preset power redistribution conditions are met, the sum of the power of each battery is taken as the total power of the battery.

[0040] The new power of the battery is the product of the percentage change in battery power and the total power of the battery.

[0041] Optionally, the total power change of each battery in the photovoltaic-storage system is obtained, including:

[0042] Obtain the output power supplied to the power grid by the photovoltaic and energy storage system;

[0043] The difference between the output power and the power demand of the power grid is taken as the total power change of each battery.

[0044] Secondly, this application discloses a converter for performing the above-described charge and discharge control method.

[0045] Optionally, the DC side of the converter is connected to at least one battery, and the AC side of the converter is connected to a load.

[0046] Optionally, the DC side of the converter is also connected to a photovoltaic module.

[0047] Thirdly, this application discloses an energy manager for executing the above-described charging and discharging control method.

[0048] Fourthly, this application discloses a combiner box for performing the above-described charge and discharge control method.

[0049] Fifthly, this application discloses a battery controller for executing the above-described charge / discharge control method.

[0050] Sixthly, this application discloses a photovoltaic energy storage system, including the aforementioned converter, or the aforementioned energy manager, or the aforementioned combiner box, or the aforementioned battery controller.

[0051] This application provides a charging and discharging control method and related apparatus. In this application, the power of each battery is determined based on the total power change and the percentage of power change in the battery. During power adjustment, this application directly allocates the total power change to each battery, thus eliminating the need to use the actual charging and discharging power of the battery. This avoids power oscillation problems caused by inaccurate acquisition of the actual charging and discharging power of the battery, resulting in smoother power adjustment and improved accuracy of SOC equalization operation, adapting to fast dynamic closed-loop response scenarios. Furthermore, in this application, the percentage of power change in the battery is determined based on the battery's state of charge and rated capacity, allowing battery capacity to be considered during power allocation. This enables each converter in the photovoltaic-storage system to connect to batteries of different capacities, achieving mixed use of batteries with different capacities. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of the structure of a photovoltaic energy storage system provided in an embodiment of this application;

[0054] Figure 2 A schematic flowchart of a charging and discharging control method provided in an embodiment of this application;

[0055] Figure 3 This is a schematic diagram of another optical energy storage system provided in an embodiment of this application;

[0056] Figure 4 A flowchart illustrating a method for calculating the charging power of a battery, provided in an embodiment of this application;

[0057] Figure 5 A flowchart illustrating a method for calculating the discharge power of a battery, provided in an embodiment of this application;

[0058] Figure 6 This is a schematic diagram of another optical energy storage system provided in an embodiment of this application;

[0059] Figure 7 This is a schematic diagram of another optical energy storage system provided in an embodiment of this application. Detailed Implementation

[0060] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] A photovoltaic-storage system, also known as a multi-unit parallel system of photovoltaic-storage converters, has the following structure: Figure 1 As shown, a photovoltaic-storage system includes multiple converters, such as converter 1, converter 2, ..., converter x, where x is a positive integer. The converters can communicate with each other via RS485 or other communication methods. A converter is an electrical device that changes the voltage, frequency, number of phases, and other electrical quantities or characteristics of a power system. Converters can be of the type found in photovoltaic-storage systems. Based on their different functions, converters can be categorized as rectifiers for converting AC to DC, inverters for converting DC to AC, or converters with bidirectional DC-AC conversion capabilities.

[0062] When there are multiple converters in a photovoltaic-storage system, the converters can be divided into converter master and converter slave. Generally, there is one converter master and multiple converter slaves.

[0063] Both the main converter and the slave converter can be connected to at least one battery; that is, the converter can be connected to one battery or multiple batteries. Figure 1 In the circuit, inverter 1 connects to two batteries, and inverter 2 connects to one battery. Each battery includes at least one cell. For example, one battery includes cell 1-cell n1, another battery includes cell 1-cell n2, yet another battery includes cell 1-cell n3, and yet another battery includes cell 1-cell n4. Here, n1, n2, n3, and n4 are all positive integers, and the values ​​of n1, n2, n3, and n4 can be the same or different.

[0064] In grid-connected scenarios, if the battery power connected to one or more converters is low, it will reduce the off-grid load capacity and stability of the entire system. In this case, the battery SOC (State of Charge) balancing operation (which keeps the SOC of battery packs or clusters relatively consistent) can be used during grid connection to maintain the SOC balance of different batteries and ensure the overall stable operation of the system.

[0065] Currently, SOC balancing in multi-unit parallel photovoltaic-storage converter systems often adopts proportional control of charging and discharging power. The SOC ratio of each battery in the total SOC is calculated based on the SOC of each battery. Then, based on the system's target charging and discharging power and the current battery's SOC ratio, the charging and discharging power of the current battery is calculated.

[0066] This approach has the following problems:

[0067] When performing SOC balancing in a closed-loop control scenario, the target charge and discharge power of the battery needs to be calculated based on the actual charge and discharge power of the battery. However, during the dynamic closed-loop adjustment process, it takes a certain amount of time to collect the power, which causes a deviation between the collected battery power and the actual battery power. This deviation will cause power oscillation and reduce the reliability of battery power adjustment, making this method unsuitable for dynamic closed-loop control scenarios.

[0068] Therefore, the battery power regulation process in this application is mostly controlled based on the total power change of all batteries rather than the total power. Furthermore, the base power of the battery power change is the power allocated in the previous cycle rather than the actual output power of the battery. This method does not require the use of the actual output power of the battery and does not have particularly strict time requirements for the acquisition of the battery output power. In a fast dynamic closed-loop response, it can also achieve smooth power regulation.

[0069] Based on the above, this application provides a charging and discharging control method, the executing entity of which can be a control device in a photovoltaic energy storage system. This control device can be an energy manager in the photovoltaic energy storage system, a converter in the system (such as the aforementioned converter host), or a combiner box or battery in the photovoltaic energy storage system.

[0070] Reference Figure 2 A charging and discharging control method may include:

[0071] S11. Obtain the total power change of each battery in the photovoltaic-storage system.

[0072] The photovoltaic-storage system also includes multiple inverters. This application does not specify the structure or type of the inverters. Each inverter connects to at least one battery. In this embodiment, the battery can be an energy storage battery, and each battery includes at least one cell. It should be noted that when multiple batteries are connected to one inverter, the multiple batteries are treated as a whole, forming a battery pack. The SOC of this battery pack refers to the sum of the SOCs of all the batteries. The entire battery pack has only one charging power or discharging power, and the batteries in the battery pack are charged and discharged according to this charging power or discharging power. That is, in this case, multiple batteries connected to the same inverter are treated as one battery to execute subsequent processing logic. The specific connection structure between the battery and the inverter can be referred to the corresponding description above.

[0073] In this embodiment, the battery operates in multiple modes. In one implementation, all batteries are charged or discharged simultaneously. That is, each battery is either charging or discharging at the same time, and it is not allowed for some batteries to be charging while others are discharging. In this case, since all batteries are in the same state of charge and discharge, the total power change of each battery refers to the total power change of all batteries.

[0074] In another implementation, some batteries are charged while others are discharged, meaning each battery can have a different state of charge / discharge. For example, out of N batteries, N1 batteries need to be charged and N2 batteries need to be discharged. In this case, the total power change of each battery is determined based on the overall state of charge / discharge of the battery system. If the charging power is greater than the discharging power, the battery system is considered to be in a charging state; if the charging power is less than the discharging power, the battery system is considered to be in a discharging state. Regardless of whether the battery system is in a charging or discharging state, the total power change of each battery refers to the total power change of all batteries. In other words, regardless of the operating mode, the total power change of each battery refers to the total power change of the battery system as a whole. Here, N1 and N2 are positive integers, and N1 and N2 can have different or the same values.

[0075] In real-world scenarios, the specific operating mode used by each battery can be determined based on the actual configuration.

[0076] In one implementation, the impact of battery capacity on power allocation is considered during power distribution. Therefore, the capacities of different batteries in this embodiment can be different, making it suitable for scenarios where battery capacities are mixed. Subsequent dynamic equalization of incremental battery power allocation based on battery SOC and battery capacity will also make the dynamic adjustment process smoother.

[0077] During operation, a photovoltaic (PV) and energy storage (ESS) system generates multiple power outputs, such as grid feed power. Grid feed power refers to the output power supplied by the PV / ESS system to the grid. This output power is related to the grid's power demand; the higher the grid's power demand, the higher the output power supplied by the PV / ESS system. Changes in the power consumption of grid-connected loads and other electrical equipment cause variations in the grid's power demand, resulting in a discrepancy between the PV / ESS system's output power and the grid's power demand, creating a power difference. In this case, the operating status during operation can be monitored to obtain the corresponding power values. For example, the difference between the PV / ESS system's output power and the grid's power demand can be used as the total power change of each battery.

[0078] The output power of the photovoltaic-storage system supplied to the grid can be collected by meters installed on the grid side. For example, if the output power of the photovoltaic-storage system supplied to the grid is 1000 kW, and the grid's power demand is 3000 kW, the difference between the output power and the grid's power demand is 2000 kW. This means the total power change of each battery is 2000 kW, and the total discharge power of all batteries needs to be adjusted from 1000 kW to 3000 kW. This ensures that the battery power changes accordingly to match the grid's power demand.

[0079] Another implementation method could be to receive the total power change of each battery from a third-party control system, such as a scheduling system. Alternatively, the total power change of each battery could be estimated based on historical operating data.

[0080] In the above embodiments, the photovoltaic-storage system is used as the main source of power for supplying electricity to the power grid. Furthermore, as... Figure 3 As shown, the photovoltaic-storage system can also be combined with photovoltaic modules to supply power to the grid. In this case, each converter can be connected to one photovoltaic module.

[0081] It should be noted that the output power of photovoltaic (PV) modules fluctuates due to the influence of sunlight intensity. When the output power of the PV modules exceeds the grid's power demand, the excess energy generated by the PV modules is stored in a photovoltaic-storage system. When the output power of the PV modules is less than the grid's power demand, the photovoltaic-storage system supplies energy to the grid. The sum of the output power of the PV modules and the output power of the photovoltaic-storage system is the grid's power demand.

[0082] At this point, the total power change of each battery is the grid demand power value minus the output power of the photovoltaic module minus the output power of the photovoltaic-storage system.

[0083] It should be noted that since the battery as a whole can be in a charging state or a discharging state, the total power change in the embodiments of this application can be the total change in charging power or the total change in discharging power of each battery.

[0084] Whether the batteries are charging and discharging simultaneously, or only some batteries are charging or discharging, if the entire battery is in a charging state, the total power change is the total power change of each battery. If the entire battery is in a discharging state, the total power change is the total power change of each battery.

[0085] S12. Determine the percentage of power change of the battery based on the battery's state of charge and rated capacity;

[0086] The power change percentage is used to indicate the battery's charging or discharging percentage.

[0087] In practical applications, related technologies do not consider the impact of battery capacity on battery SOC balancing, and cannot support scenarios where batteries of different capacities are used in combination. Therefore, in this embodiment, battery capacity is also included in the calculation of the charge / discharge ratio, so that the multi-machine parallel system can be compatible with scenarios where battery capacities are mixed, allowing batteries of different capacities to be connected to each converter.

[0088] In real-world scenarios, because different batteries have different states of charge (SOC), if each battery is charged and discharged at the same power, some batteries will have a lower SOC while others will have a higher SOC, reducing the overall off-grid load capacity and stability of the system. Therefore, in this embodiment, different charging and discharging powers are used for batteries with different SOCs.

[0089] Different charging and discharging powers result in different power change percentages. In a battery charging scenario, the power change percentage represents the battery's charging percentage, while in a battery discharging scenario, the power change percentage represents the battery's discharging percentage.

[0090] Specifically, when calculating the percentage change in power for each battery, this application considers not only the differences in State of Charge (SOC) of each battery but also their rated capacity. This is because the batteries connected to the inverter may be mixed. If power allocation is based solely on SOC, batteries with smaller rated capacities may have higher power outputs, while batteries with larger rated capacities may have lower power outputs, resulting in a mismatch between battery power and rated capacity, and consequently, low accuracy in power allocation. Therefore, in this embodiment, the influence of battery rated capacity on power allocation is considered, thereby improving the accuracy of battery power allocation.

[0091] Optionally, there are multiple ways to determine the percentage of power change of a battery based on its state of charge and rated capacity. For example, in one implementation, the product of the battery's state of charge and rated capacity can be used as the battery's remaining energy. Then, the ratio of the battery's remaining energy to the total remaining energy can be calculated, and this ratio can be used as the battery's discharge percentage. Here, the total remaining energy is the sum of the remaining energy of all batteries.

[0092] In practical implementation, when determining the discharge percentage of each battery, the discharge percentage of the corresponding battery is determined based on the remaining energy of that battery. The remaining energy of a battery refers to the remaining charge of the battery, which is related to the battery's state of charge and rated capacity. In one implementation, the remaining energy of the k-th battery = Soc_k * Capacity_k, where Soc_k is the state of charge of the k-th battery, and Capacity_k is the rated capacity of the k-th battery.

[0093] After calculating the remaining energy of the battery, the discharge percentage of the battery can be calculated using that remaining energy.

[0094] The formula for calculating the discharge percentage of the k-th battery is as follows:

[0095]

[0096] DisCRatio_k=(Soc_k*Capacity_k) / BatRE;

[0097] Where BatRE is the sum of the remaining energy of all batteries in the photovoltaic-storage system, n is the total number of batteries in the photovoltaic-storage system, Soc_k is the state of charge of the k-th battery (also known as the battery under the k-th converter), Capacity_k is the rated capacity of the k-th battery, and DisCRatio_k is the discharge ratio of the k-th battery.

[0098] Optionally, the difference between the battery's rated capacity and its remaining energy can be calculated, and the ratio of this difference to the total remaining energy can be used as the battery's charging percentage.

[0099] To elaborate, the formula for calculating the charging percentage of the k-th battery is:

[0100] CRation_k=((1-Soc_k)*Capacity_k) / BatRE;

[0101] Where CRation_k represents the charging percentage of the k-th battery, and the meanings of the other formulas are explained in the corresponding descriptions above.

[0102] In this embodiment, the remaining energy of the battery is considered when calculating the charging and discharging percentages. The remaining energy of the battery is obtained based on the rated capacity and state of charge, so that an accurate charging and discharging percentage can be allocated to the battery based on its current SOC and rated capacity.

[0103] S13. Based on the total power change and the percentage of power change of each battery, determine the power of each battery.

[0104] Power includes charging power or discharging power.

[0105] In practical implementation, once the total power change and the percentage of power change of the battery (including the percentage of charging and discharging) are known, the total power change can be allocated according to the percentage of power change of the battery to obtain the power change of each battery in the current cycle. For example, the power change percentage of the battery can be multiplied by the total power change to obtain the power change of the battery in the current cycle.

[0106] Furthermore, the charging and discharging power of the battery in the current cycle is calculated based on the power change of the battery in the current cycle. For example, the sum of the power change of the battery in the current cycle and the power of the previous cycle can be used as the charging and discharging power of the battery in the current cycle, so as to perform the charging and discharging operation of the battery. Here, the charging and discharging power includes charging power or discharging power.

[0107] S14. Use the battery's power to control the charging or discharging of the battery.

[0108] In this step, after obtaining the charging power of the battery connected to the inverter, the battery can be controlled to perform charging operations according to that charging power. Similarly, after obtaining the discharging power of the battery connected to the inverter, the battery can be controlled to perform discharging operations according to that discharging power.

[0109] All batteries can be charged or discharged simultaneously, or some batteries can be charged while others are discharged. The specific operating mode can be determined based on the actual configuration.

[0110] It should be noted that in the working mode where all batteries can be charged or discharged at the same time, if the power of a certain battery is consistent with the charging or discharging state of the battery, then that power will be used for charging or discharging operations. If the power of a certain battery is inconsistent with the charging or discharging state of the battery, then the power of that battery can be zero, so as to ensure that the charging and discharging state of all batteries is consistent.

[0111] In scenarios where some batteries are charging and others are discharging, since the charging and discharging states of each battery may be inconsistent, each battery can be charged or discharged according to its actual power.

[0112] In this embodiment, the power of each battery is determined based on the total power change and the percentage of power change per battery. During power adjustment, this application directly allocates the total power change to each battery, eliminating the need to use the actual charging and discharging power of the batteries. This avoids power oscillations caused by inaccurate acquisition of the actual charging and discharging power, resulting in smoother power adjustment and improved accuracy of SOC balancing operation. This ensures balanced battery SOC and adapts to fast dynamic closed-loop response scenarios. Furthermore, in this application, the percentage of power change per battery is determined based on the battery's state of charge and rated capacity. This allows battery capacity to be considered during power allocation, enabling each converter in the photovoltaic-storage system to connect to batteries of different capacities, facilitating the mixed use of batteries with varying capacities.

[0113] The above embodiments mention that the battery power allocation operation needs to utilize the total power change during charging and discharging operations. Since charging and discharging operations are divided into charging and discharging operations, and charging operations can be further divided into increasing and decreasing battery charging power, and similarly, discharging operations can also be divided into increasing and decreasing battery discharging power, this embodiment can describe the battery power allocation process in each operating scenario based on the charging and discharging conditions. These operating scenarios include increasing battery discharging power, decreasing battery discharging power, increasing battery charging power, and decreasing battery charging power.

[0114] Specifically, if the battery in the current photovoltaic-storage system is in a discharging state, and the total power change indicates that a certain amount of discharge power needs to be increased, then the current operating scenario is a scenario of increasing battery discharge power.

[0115] If the batteries in the current photovoltaic-storage system are in a discharging state, and the total power change indicates that a certain amount of discharge power needs to be reduced, then the current operating scenario is a scenario of reducing battery discharge power.

[0116] If the battery in the current photovoltaic-storage system is in a charging state, and the total power change indicates that a certain amount of charging power needs to be increased, then the current operating scenario is a scenario of increasing battery charging power.

[0117] If the battery in the current photovoltaic-storage system is in a charging state, and the total power change is a reduction in charging power, then the current operating scenario is a scenario of reducing battery charging power.

[0118] In one implementation, when the total change in power is equal to the total change in charging power, it indicates that the current operating scenario is a charging scenario. This scenario is further subdivided into two cases: a scenario that increases battery charging power and a scenario that decreases battery charging power.

[0119] In one embodiment, in scenarios where increased battery charging power is required, determining the power of each battery based on the total power change and the percentage of power change per battery can be as follows:

[0120] For each battery, the product of the total change in charging power and the battery's charging percentage is calculated to obtain the power change of the battery in the current cycle. Then, the sum of the charging power of the battery in the previous cycle and the power change of the battery in the current cycle is taken as the charging power of the battery in the current cycle.

[0121] Specifically, when it is necessary to increase the battery charging power, since the sum of the increased charging power of all batteries is the total power change mentioned above, the total power change can be allocated to obtain the power change of each battery in the current cycle. This power change specifically refers to the change in charging power.

[0122] When allocating power, since different batteries have different states of charge (SOC), an equal distribution would result in some batteries having lower SOCs, affecting the system's off-grid load capacity and stability. Therefore, in this embodiment, instead of equal distribution, the total power change is allocated according to the proportion of power change in each battery, resulting in the power change amount for each battery. Knowing the power change amount for each battery, the charging power for that battery is calculated, and the battery can then be charged according to that power.

[0123] Since the goal is to increase the battery's charging power, it is necessary to know the baseline for increasing the battery's charging power. This baseline is the battery's charging power in the previous cycle. Therefore, it is necessary to obtain the battery's charging power in the previous cycle and sum the change in the battery's charging power with the battery's charging and discharging power in the previous cycle. This sum is the battery's charging and discharging power in the current cycle.

[0124] Specifically, when increasing battery charging power, the percentage change in battery power refers to the percentage change in charging power, where the percentage change in charging power for the k-th battery is denoted as CCRRaation_kk. The formula for calculating the battery power change ΔPbat_k is as follows:

[0125] ΔPbat_k=CRatio_k*ΔPbat

[0126] Where CRatio_k is the charging percentage of the k-th battery, and ΔPbat is the total power change, specifically the total change in charging power.

[0127] The actual charging power Pbat_k allocated to the battery in the current cycle scheduling is then... 充 The calculation formula is:

[0128] Pbat_k 充 =Pbat_kLast 充 +ΔPbat_k.

[0129] Among them, Pbat_kLast 充 ΔPbat_k represents the charging power of the battery in the previous cycle, and ΔPbat_k represents the change in battery power.

[0130] In this embodiment, power allocation is performed directly using the total power change. Furthermore, when allocating power based on the total power change, the charging power allocated in the previous cycle is used to calculate the charging power of the battery in the current cycle, eliminating the need to use the collected battery power and thus avoiding the power oscillation problem caused by using the collected battery power.

[0131] When it is necessary to reduce battery charging power, refer to Figure 4When determining the power of each battery based on the total power change and the percentage of power change in the battery, the following steps may also be included:

[0132] S21. Obtain the total charging power of all batteries.

[0133] Based on any of the above embodiments, if it is necessary to reduce the battery charging power while the battery is charging, the battery may still be in a charging state after the charging power is reduced, or it may switch from a charging state to a discharging state. At this time, the battery charging and discharging state is switched. Therefore, in this embodiment, when reducing the battery charging power, it is necessary to determine whether the battery charging and discharging state has switched.

[0134] One method of determination involves comparing the total charging power of all batteries with the total change in charging power to determine whether a state switch is necessary. Therefore, in this embodiment, it is necessary to obtain the total charging power of all batteries.

[0135] The total charging power of all batteries refers to the sum of the charging power of each individual battery. The charging power of each individual battery can be collected, and the sum of the charging power of all batteries can be calculated to obtain the total charging power of all batteries.

[0136] It should be noted that the charging power of each battery can be collected according to the power acquisition cycle. When it is necessary to calculate the total charging power of all batteries, the charging power of each battery can be directly obtained and the total charging power of all batteries can be calculated.

[0137] S22. If the total charging power of all batteries is greater than or equal to the total change in charging power, then for each battery, calculate the product of the total change in charging power and the battery's charging percentage to obtain the power change of the battery in the current cycle.

[0138] If the total charging power of all batteries is greater than or equal to (i.e. not less than) the total change in charging power, it means that the difference between the current total charging power of all batteries and the total change in charging power is positive. In this case, after the total charging power of all batteries is reduced, they will still work according to the original charging state and there is no need to switch between charging and discharging scenarios.

[0139] In practice, the total charging power PbatReal of all batteries is obtained. 充 And obtain the total power change Δpbat, which specifically refers to the total change in charging power.

[0140] If it is PbatReal 充If –Δpbat>=0, it means that when the total charging power of all batteries is reduced, the power reduction is less than the total charging power of all batteries. After the power is reduced, the overall charging power of the batteries is greater than zero, and the batteries are still in the charging state and do not need to switch to the discharging state.

[0141] If it is PbatReal 充 -ΔPbat<0 indicates that when the total charging power of all batteries is reduced, the power reduction is greater than the total charging power of all batteries. After the power is reduced, the overall charging power of the batteries is less than zero, and the batteries need to switch from charging to discharging.

[0142] It should be noted that in this embodiment, PbatReal is compared. 充 When calculating the magnitude of -ΔPbat and 0, first calculate PbatReal. 充 When the difference -ΔPbat is compared with zero, in PbatReal 充 When the difference between Pbat and ΔPbat is large, even if PbatReal 充 Even if there is a deviation in the data acquisition, it will not affect the comparison result between the difference and zero. Using this comparison result for power adjustment results in less power oscillation, making power control smoother.

[0143] Only in PbatReal 充 When the difference between Pbat and ΔPbat is small, PbatReal 充 Only acquisition bias will affect the comparison result between the difference and zero, which will cause power oscillation. However, due to PbatReal 充 The time period with a small difference from ΔPbat is relatively short, resulting in a shorter period of power oscillation, which does not affect the smoothness of the overall power control.

[0144] In one implementation, when the total charging power is greater than or equal to the total change in charging power, since there is no need to switch between charging and discharging states, it is only necessary to distribute the total change in charging power to each battery according to the proportion of the battery's power change to obtain the power change of the battery. When the charging power is reduced, this power change specifically refers to the power reduction.

[0145] In a scenario where battery charging power is reduced without switching to discharging, for the k-th battery, the power reduction change ΔPbat_k is calculated based on the charging percentage and is given by the formula: ΔPbat_k = CRation_k * ΔPbat.

[0146] Where CRatio_k is the charging percentage of the k-th battery, and ΔPbat is the total power change, specifically the total change in charging power.

[0147] S23. When the charging and discharging states of all batteries do not need to be consistent, the difference between the charging power of the battery in the previous cycle and the power change of the battery in the current cycle shall be taken as the charging power of the battery in the current cycle.

[0148] In this embodiment, the fact that the charge / discharge states of all batteries do not need to be consistent means that some batteries are allowed to charge while others are allowed to discharge. In this embodiment, the actual charging power Pbat_k allocated to the batteries in the current cycle is... 充 The calculation formula is:

[0149] Pbat_k 充 =Pbat_kLast 充 -ΔPbat_k.

[0150] Among them, Pbat_kLast 充 ΔPbat_k represents the charging power of the battery in the previous cycle, and ΔPbat_k represents the change in battery power.

[0151] If it is Pbat_k 充 If it is a positive number, the battery continues to charge; if it is Pbat_k 充 If the value is negative, the battery changes from charging to discharging.

[0152] S24. If the charging and discharging states of all batteries need to remain consistent, and if the charging power of the battery in the previous cycle is greater than the power change of the battery in the current cycle, the difference between the charging power of the battery in the previous cycle and the power change of the battery in the current cycle shall be taken as the charging power of the battery in the current cycle; if the charging power of the battery in the previous cycle is less than or equal to the power change of the battery in the current cycle, the charging power of the battery in the current cycle shall be set to zero.

[0153] Specifically, maintaining a consistent state of charge and discharge for all batteries means that all batteries need to be charged or discharged simultaneously. If the charging power of a battery in the previous cycle is greater than the power change in the current cycle, it indicates that the battery does not need to switch from charging to discharging after the charging power decreases. In this case, the charging power can still be determined by using the difference between the charging power of the battery in the previous cycle and the power change in the current cycle as the charging power of the battery in the current cycle.

[0154] If the charging power of a battery in the previous cycle is less than or equal to the change in power in the current cycle, it means that a battery needs to switch from charging to discharging due to a decrease in power. Since it is necessary to maintain a consistent charging and discharging state for batteries that need to be charged or discharged simultaneously, its charging state can only be set to zero.

[0155] Therefore, the actual charging power allocated to the battery in this dispatch is:

[0156] When (Pbat_kLast) 充 When -ΔPbat_k>=0): Pbat_k 充 =Pbat_kLast 充 -ΔPbat_k;

[0157] When (Pbat_kLast) 充 When -ΔPbat_k<0): Pbat_k 充 =0.

[0158] This embodiment provides two scenarios for reducing battery charging power, thereby enabling the corresponding charging power of the battery to be obtained in both cases where the battery charging and discharging states need to be kept consistent and cases where they do not need to be kept consistent.

[0159] The above embodiments describe the logic for determining charging power when the total charging power of all batteries is greater than or equal to the total change in charging power. Based on any of the above embodiments, another implementation of this application provides the determination of charging power when the total charging power of all batteries is less than the total change in charging power. Specifically, in determining the power of each battery based on the total change in power and the percentage of power change in each battery, the following may also be included:

[0160] If the total charging power of all batteries is less than the total change in charging power, calculate the difference between the total change in charging power and the total charging power to obtain the power difference. Then, multiply the battery's discharge percentage by the power difference as the battery's discharge power in the current cycle.

[0161] Specifically, when the total charging power of all batteries is less than the total change in charging power, it means that the difference between the current total charging power of all batteries and the total change in charging power is negative. At this time, after the total charging power of all batteries decreases, the original charging state changes and switches to the discharging state, which means that a charge / discharge scenario switch is required. When a charge / discharge state switch is required, a power allocation operation needs to be performed on all batteries again.

[0162] When reducing the battery charging power to switch the battery from a charging state to a discharging state, the total charging power required after switching back to charging is: Pbat = ΔPbat – PbatReal 充 Here, ΔPbat refers to the total change in power; specifically, during battery charging, it refers to the total change in charging power, PbatReal. 充 Pbat refers to the power difference, which represents the total charging power. Pbat represents the total power required to be allocated to all batteries when power distribution is needed. In this embodiment, Pbat needs to be allocated to each battery according to the charging ratio.

[0163] Given Pbat, calculate the product of Pbat and the discharge percentage to obtain the battery's discharge power in the current cycle. Then, when reducing the battery charging power to switch the battery from charging to discharging, the discharge power allocated to each battery is: Pbat_k 放 =DisCRatio_k*Pbat, where DisCRatio_k refers to the discharge ratio.

[0164] In this embodiment, if the charging power that needs to be reduced is large enough to require the battery to switch from charging to discharging, then all the power of the battery is redistributed to ensure the accuracy of the power distribution for each battery.

[0165] The above embodiments describe the processing logic for increasing or decreasing battery charging power. In another implementation of this application, the processing logic for increasing or decreasing battery discharging power is described. In this case, the total power change is the total discharge power change. This situation is further subdivided into two cases: increasing battery discharge power and decreasing battery discharge power.

[0166] In one implementation, when it is necessary to increase the battery discharge power, the power of each battery can be determined based on the total power change and the percentage of power change in the battery.

[0167] For each battery, the product of the total change in discharge power and the battery's discharge percentage is calculated to obtain the power change of the battery in the current cycle. The sum of the battery's discharge power in the previous cycle and the power change of the battery in the current cycle is taken as the battery's discharge power in the current cycle.

[0168] Specifically, when increasing battery discharge power, the percentage change in battery power refers to the discharge percentage, where the discharge percentage of the k-th battery is denoted as DisCRatio_k. The formula for calculating the battery power change ΔPbat_k within the current cycle is:

[0169] ΔPbat_k=DisCRation_k*ΔPbat.

[0170] Where DisCRation_k is the discharge percentage of the k-th battery, and ΔPbat is the total power change, specifically the total change in discharge power.

[0171] So, the actual discharge power Pbat_k sent to the battery in the current cycle scheduling 放 for:

[0172] Pbat_k 放 =Pbat_kLast 放 +ΔPbat_k.

[0173] Among them, Pbat_kLast 放 ΔPbat_k represents the battery's discharge power in the previous cycle, and ΔPbat_k represents the change in the battery's power.

[0174] In this embodiment, the total amount of charging power change is allocated according to the proportion of battery power change, without needing to use the real-time power of the battery, thereby avoiding the problem of inaccurate power allocation caused by inaccurate real-time power acquisition.

[0175] In another implementation of this application, when it is necessary to reduce battery discharge power, refer to... Figure 5 When determining the power of each battery based on the total power change and the percentage of power change in the battery, the following may also be included:

[0176] S31. Obtain the total discharge power of all batteries.

[0177] In this embodiment, reducing battery discharge power is the same as reducing battery charging power; it requires obtaining the total discharge power PbatReal of all batteries. 放 And obtain the total power change Δpbat, which specifically refers to the total change in discharge power.

[0178] S32. If the total discharge power of all batteries is greater than or equal to the total change in discharge power, then for each battery, calculate the product of the total change in discharge power and the discharge percentage of the battery to obtain the power change of the battery in the current cycle.

[0179] Specifically, if it is PbatReal 放 –Δpbat 放 If the value is greater than or equal to 0, it means that when the total discharge power of all batteries is reduced, the power reduction is less than the total discharge power of all batteries. After the power is reduced, the battery discharge power is greater than zero, and the battery is still in the discharge state and does not need to be switched to the charging state.

[0180] If it is PbatReal 放 -ΔPbat 放 A value <0 indicates that when the total discharge power of all batteries is reduced, the power reduction is greater than the total discharge power of all batteries. After the power is reduced, the battery discharge power is less than zero, and the battery needs to switch from the discharge state to the charging state.

[0181] It should be noted that in this embodiment, PbatReal is compared. 放 -ΔPbat 放 When dealing with a value of 0, first calculate PbatReal. 放 -ΔPbat 放 When the difference is compared with zero, in PbatReal放 With ΔPbat 放 When the sizes differ significantly, even PbatReal 放 Even if there is a deviation in the data acquisition, it will not affect the comparison result between the difference and zero. Therefore, the power oscillation is smaller, making the power control smoother.

[0182] Only in PbatReal 放 With ΔPbat 放 When the size difference is small, PbatReal 放 Only acquisition bias will affect the comparison result between the difference and zero, which will cause power oscillation. However, due to PbatReal 放 With ΔPbat 放 The time periods with smaller magnitude differences are shorter, resulting in shorter periods of power oscillation, which does not affect the smoothness of the overall power control.

[0183] In this embodiment, the total discharge power of all batteries is greater than or equal to the total change in discharge power, i.e., PbatReal 放 –Δpbat 放 When the value is greater than or equal to 0, since there is no need to switch between charging and discharging states, it is only necessary to distribute the total change in discharge power to each battery according to the discharge ratio of the battery to obtain the power change of the battery in the current cycle.

[0184] At this point, in a scenario where the battery discharge power is reduced and there is no need to switch to charging, the power conversion amount of the k-th battery is ΔPbat_k = DisCRation_k * ΔPbat.

[0185] Where DisCRation_k is the discharge percentage of the k-th battery, ΔPbat 放 This represents the total change in discharge power.

[0186] S33. When the charging and discharging states of all batteries do not need to be consistent, the difference between the battery's discharge power in the previous cycle and the change in battery power in the current cycle shall be taken as the battery's discharge power in the current cycle.

[0187] In this embodiment, the statement that the charge / discharge state of all batteries does not need to be consistent means that some batteries are allowed to charge while others are allowed to discharge.

[0188] Since the battery's discharge power in the current cycle is related to the battery's discharge power in the previous cycle and the magnitude of the battery's power change, in this embodiment, the actual discharge power Pbat_k scheduled to be given to the battery in the current cycle is... 放 for:

[0189] Pbat_k 放 =Pbat_kLast放 -ΔPbat_k.

[0190] Among them, Pbat_kLast 放 It refers to the battery's discharge power in the previous cycle, and ΔPbat_k is the change in the battery's power.

[0191] If it is Pbat_k 放 If it is a positive number, the battery continues to discharge; if it is Pbat_k 放 If the value is negative, the battery changes from a discharging state to a charging state.

[0192] S34. If the charging and discharging states of all batteries need to remain consistent, and if the battery's discharge power in the previous cycle is greater than the battery's power change in the current cycle, the difference between the battery's discharge power in the previous cycle and the battery's power change in the current cycle shall be taken as the battery's discharge power in the current cycle; if the battery's discharge power in the previous cycle is less than or equal to the battery's power change in the current cycle, the battery's discharge power in the current cycle shall be set to zero.

[0193] Specifically, when reducing battery discharge power, if the battery's discharge power in the previous cycle is Pbat_kLast 放 The power change ΔPbat_k is greater than or equal to that of the battery, and Pbat_kLast 放 -ΔPbat_k>=0 indicates that even if Pbat_kLast is reduced according to the change in battery power ΔPbat_k, 放 If the obtained discharge power is still greater than zero after the value is calculated, the battery is still in a discharge state. In this case, the difference between the battery's discharge power in the previous cycle and the change in battery power is directly taken as the battery's discharge power in the current cycle.

[0194] The actual discharge power Pbat_k sent to the battery in the current cycle scheduling is then... 放 for:

[0195] Pbat_k 放 =Pbat_kLast 放 -ΔPbat_k.

[0196] Among them, Pbat_kLast 放 It refers to the battery's discharge power in the previous cycle, and ΔPbat_k is the change in the battery's power.

[0197] The battery's discharge power Pbat_kLast in the previous cycle 放 When it is less than the change in battery power ΔPbat_k, i.e., Pbat_kLast 放If -ΔPbat_k < 0, reducing the battery charging and discharging power by ΔPbat_k will cause the battery's discharging power to be less than zero, thus switching the battery from a discharging state to a charging state. However, as discussed above, this control method is only applicable in scenarios where the charging and discharging power is not switched. Therefore, the battery's discharging power Pbat_k can only be reduced. 放 Set it to zero to stop the battery from charging and discharging; that is, at this time, Pbat_k 放 =0.

[0198] This embodiment provides two scenarios for reducing battery discharge power, thereby enabling the corresponding battery discharge power to be obtained in both cases where the battery charge and discharge states need to be kept consistent and cases where they do not need to be kept consistent.

[0199] The above embodiments describe the logic for determining discharge power when the total discharge power of all batteries is greater than or equal to the total change in discharge power. Based on any of the above embodiments, another implementation of this application provides the determination of discharge power when "the total discharge power of all batteries is less than the total change in discharge power". Specifically, determining the power of each battery based on the total change in power and the percentage of power change in each battery further includes:

[0200] If the total discharge power of all batteries is less than the total change in discharge power, calculate the difference between the total change in discharge power and the total discharge power to obtain the power difference. Then, the product of the battery's charging percentage and the power difference is taken as the battery's charging power in the current cycle.

[0201] In this embodiment, when the total discharge power is less than the total change in discharge power, a charge / discharge state switch is required. When a charge / discharge state switch is required, a power allocation operation needs to be performed on all batteries.

[0202] When reducing the battery discharge power to switch the battery from a discharging state to a charging state, the total charging power required after switching to charging is: Pbat = ΔPbat – PbatReal 放 .

[0203] Where ΔPbat refers to the total change in power, PbatReal 放 Pbat represents the total discharge power, while Pbat refers to the power difference.

[0204] In this embodiment, Pbat represents the total power required for power allocation when all batteries need to be allocated. Since it is necessary to switch from the discharging state to the charging state, Pbat is allocated to each battery according to the charging ratio.

[0205] In this embodiment, after Pbat is known, the product of Pbat and the charging percentage is calculated to obtain the charging power of the battery in the current cycle.

[0206] Specifically, when reducing the battery discharge power to switch the battery from a discharging state to a charging state, the charging power allocated to each battery is: Pbat_k 充 =CRatio_k*Pbat, where CRatio_k refers to the charging percentage.

[0207] In this embodiment, the total amount of discharge power change is allocated according to the proportion of battery power change, without needing to use the real-time power of the battery, thereby avoiding the problem of inaccurate power allocation caused by inaccurate real-time power acquisition.

[0208] As can be seen from the above embodiments, the power allocation logic under various scenarios is introduced. Now, all scenarios are summarized and introduced to give a clear view of the power allocation logic under various scenarios.

[0209] A. Increase battery charging power:

[0210] For the battery under the k-th inverter, the charging power that needs to be increased according to the charging ratio is: ΔPbat_k=CRatio_k*ΔPbat.

[0211] The actual charging power allocated to the battery in this dispatch is: Pbat_k 充 =Pbat_kLast 充 +ΔPbat_k.

[0212] B. Reduce battery charging power:

[0213] First, determine if the battery needs to be switched from charging to discharging:

[0214] If it is PbatReal 充 If Δpbat >= 0, then there is no need to switch to discharge.

[0215] If it is PbatReal 充 If -ΔPbat < 0, then it is necessary to switch to discharge mode.

[0216] Scenarios where switching to discharge is not required:

[0217] For the battery under the k-th inverter, the charging power that needs to be reduced according to the charging ratio is: ΔPbat_k=CRation_k*ΔPbat;

[0218] The actual discharge power allocated to the battery in this dispatch was:

[0219] When (Pbat_kLast) 充 When -ΔPbat_k>=0): Pbat_k 充 =Pbat_kLast 充-ΔPbat_k;

[0220] When (Pbat_kLast) 充 When -ΔPbat_k<0): Pbat_k 充 =0.

[0221] Scenarios requiring switching to discharge mode:

[0222] Total charging power required after switching to discharge: Pbat = ΔPbat – PbatReal 充 ;

[0223] The discharge power allocated to each battery group is: Pbat_k 充 =DisCRatio_k*Pbat.

[0224] C. Increase battery discharge power:

[0225] For the battery under the k-th inverter, the increase in discharge power based on the discharge ratio is: ΔPbat_k 放 =DisCRation_k*ΔPbat.

[0226] The actual discharge power assigned to the battery in this dispatch is: Pbat_k 放 =Pbat_kLast 放 +ΔPbat_k.

[0227] D. Reduce battery discharge power:

[0228] First, determine whether the battery needs to be switched from discharging to charging;

[0229] Among them, if PbatReal 放 If Δpbat>=0, then there is no need to switch to charging.

[0230] If it is PbatReal 放 If -ΔPbat < 0, then you need to switch to charging mode.

[0231] For scenarios where switching to charging is not required

[0232] For the battery under the k-th inverter, the discharge power that needs to be reduced according to the discharge ratio is: ΔPbat_k=DisCRation_k*ΔPbat

[0233] The actual discharge power allocated to the battery in this dispatch was:

[0234] When (Pbat_kLast) 放 When -ΔPbat_k>=0): Pbat_k 放 =Pbat_kLast 放-ΔPbat_k;

[0235] When (Pbat_kLast) 放 When -ΔPbat_k<0): Pbat_k 放 =0.

[0236] For scenarios where switching to charging is required;

[0237] Total charging power required after switching to charging mode: Pbat = ΔPbat – PbatReal 放 ;

[0238] The charging power allocated to each battery group is: Pbat_k 放 =CRatio_k*Pbat.

[0239] In this embodiment, except before the battery charging / discharging state switches, the adjustment is performed on the incremental power, i.e., the total power change mentioned above. This method does not have particularly strict time requirements for the acquisition of battery output power, and the entire adjustment process is smoother. The PbatReal value is only used when the battery charging / discharging state switches, so that the power oscillation problem caused by PbatReal only exists when the charging / discharging state switches. However, since the time period for switching charging / discharging states is very short, there is only a very small period of power oscillation, and the power adjustment is smooth most of the time, improving the reliability of power adjustment.

[0240] In addition, because the adjustment is based on the incremental battery power required by the system, even if one or more batteries cannot respond normally, the remaining normal batteries can be adjusted by continuously adding incremental power to achieve the system's output target.

[0241] Based on any of the above embodiments, during the process of adjusting the battery charging and discharging power according to the above control method, if a certain battery has its own problem, the actual charging and discharging power of a certain battery may be inconsistent with the required charging and discharging power. This may result in a deviation between the actual charging and discharging power of the system and the target value due to the actual charging and discharging power of a certain battery not meeting the standard.

[0242] Therefore, in this application, power redistribution is performed periodically based on the actual power of each battery to avoid deviations in the total charge / discharge power when a battery's actual charge / discharge power fails to meet the power requirement corresponding to the SOC proportional coefficient due to its own issues. Thus, in one implementation,

[0243] Therefore, in this embodiment of the application, a power redistribution operation can be performed at a certain period to correct batteries whose actual charging and discharging power does not meet the standard.

[0244] In one implementation, the charge / discharge control method further includes:

[0245] Under the condition of satisfying the preset power redistribution, the sum of the power of each battery is taken as the total power of the battery. Furthermore, the product of the percentage change in battery power and the total power of the battery is taken as the new power of the battery.

[0246] The preset power redistribution conditions can include reaching the power redistribution cycle, encountering a fault, system startup, or receiving a power redistribution command, at which point the battery power is redistributed. The power redistribution cycle can be configured, such as once every two minutes. Within two minutes, power redistribution can be performed according to the incremental power redistribution logic. The execution cycle of one incremental power redistribution logic step can be 200ms, so within two minutes, incremental power redistribution is performed every 200ms. At the two-minute mark, the battery power redistribution is performed according to the power redistribution cycle.

[0247] The process of battery power redistribution is explained using the preset power redistribution conditions to achieve the power redistribution cycle as an example.

[0248] At the current moment, which is the power redistribution cycle moment, the charging and discharging power of each battery is acquired. The charging and discharging power of the k-th battery is Pbatreal_k, and the total number of batteries is n. The sum of the charging and discharging power of each battery is the total charging and discharging power PbatReal at the power redistribution cycle moment. This total charging and discharging power can be called the total battery power, and its calculation formula is as follows:

[0249]

[0250] Given the total charge and discharge power PbatReal at a known power redistribution cycle, this power needs to be allocated according to the percentage change in battery power.

[0251] Specifically, if the system is in a discharging state, then the charging and discharging power of the battery under the k-th converter, i.e., the k-th battery, at the moment of the power redistribution cycle is:

[0252] Pbat_k=DisCRatio_k*PbatReal.

[0253] If the system is in a charging state, the charging and discharging power of the battery under the k-th inverter at the power redistribution cycle is:

[0254] Pbat_k = CRatio_k * PbatReal.

[0255] Where DisCRatio_k is the discharge percentage of the k-th battery, and CRatio_k is the charging percentage of the k-th battery.

[0256] In this embodiment, the full redistribution of battery power is performed periodically. Since the actual charging and discharging power of the battery is obtained when the preset power redistribution condition is met, and the battery power is fully redistributed, the problem of large deviation between the actual power and the required power of the system caused by the power of a certain battery not being in accordance with the required power for a long time can be avoided. It can also solve the problem that the actual battery charging and discharging power is not output in a balanced ratio due to disturbances, battery SOC jumps, or restart behavior.

[0257] In another implementation of this application, a converter is disclosed for performing the above-described charge-discharge control method.

[0258] In one implementation, the DC side of the converter is connected to at least one battery, and the AC side of the converter is connected to the load.

[0259] A schematic diagram of a photovoltaic energy storage system is shown below. Figure 6 As shown, the converter in this embodiment is an inverter. Since there are multiple inverters, the inverter is divided into inverter master and inverter slave.

[0260] The inverter's DC (Direct Current) side is connected to at least one battery via a DC power line. Each battery can consist of multiple cells. The inverter communicates with the battery via a CAN (Controller Area Network) bus, and the inverters communicate with each other via RS485 bus, etc. The inverter's AC (Alternating Current) side is connected to a combiner box via an AC power line. The combiner box directly connects to the load and to the power grid via a meter. The inverter can monitor and manage modules such as the battery, combiner box, load, and power grid.

[0261] When the inverter executes the above-mentioned charging and discharging control method, it can be executed by the inverter master or by a certain inverter slave. The inverter executing this method needs to obtain the output power of the photovoltaic energy storage system to the grid, take the difference between the output power and the grid demand power value as the total power change of each battery, and then perform the charging and discharging power distribution operation of the battery according to the total power change, and send the charging power or discharging power of the battery to the corresponding battery so that the battery can perform the corresponding charging and discharging operation according to the charging power or discharging power.

[0262] In another implementation of this application, the DC side of the converter is also connected to the photovoltaic module.

[0263] like Figure 7 As shown, the DC side of the inverter is connected to the battery and photovoltaic (PV) modules via DC power lines. The inverter can also monitor and manage the PV modules.

[0264] In another implementation of this application, an energy manager is disclosed for executing the above-described charging and discharging control method.

[0265] Specifically, the energy manager can be a controller in a photovoltaic energy storage system. The controller can communicate directly with each battery or indirectly through the inverter, allocate the charging and discharging power of the batteries according to the total power change, and send the charging or discharging power of the batteries directly or indirectly through the inverter to the corresponding batteries so that the batteries can perform the corresponding charging and discharging operations according to the charging or discharging power.

[0266] In another implementation of this application, a combiner box is disclosed for performing the above-described charging and discharging control method.

[0267] like Figure 7 As shown, a communication link between the combiner box and the battery can be configured. This communication link can use either CAN communication or RS485 communication. Furthermore, a communication link between the combiner box and the inverter can also be configured, in which case the combiner box indirectly performs battery power distribution operations through the inverter. Additionally, a communication link between the combiner box and the energy manager can also be configured, in which case the combiner box indirectly performs battery power distribution operations through the energy manager.

[0268] After the charging or discharging power of each battery is determined in the combiner box, the corresponding power can be directly sent to the corresponding battery, or indirectly sent to the corresponding battery through the inverter, or indirectly sent to the corresponding battery through the energy manager, so as to realize the battery power adjustment operation.

[0269] In another implementation of this application, a battery controller is disclosed for executing the above-described charge-discharge control method.

[0270] In this embodiment, the battery controller can be the controller of any battery in the photovoltaic-storage system. The battery controller can communicate with other batteries directly or through an inverter. After obtaining the charging or discharging power of each battery, the battery controller transmits the power to the corresponding battery directly or through an inverter to achieve battery power regulation.

[0271] In this embodiment, the above-mentioned charging and discharging control method can be implemented through various devices in the photovoltaic-storage system. Furthermore, the corresponding devices can be configured to implement the charging and discharging control method according to the needs, so as to achieve the purpose of adjusting the battery power according to the power demand of the power grid.

[0272] Based on the above-described embodiments of the control device, another embodiment of this application provides a photovoltaic energy storage system, including the aforementioned inverter, or the aforementioned energy manager, or the aforementioned combiner box, or the aforementioned battery controller. A schematic diagram of the photovoltaic energy storage system can be found [here]. Figure 7 As shown.

[0273] This application also provides a computer program product including computer-readable instructions, which, when executed on an electronic device, cause the electronic device to implement any of the charging and discharging control methods provided in this application.

[0274] This application also provides a computer-readable storage medium that carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any of the charging and discharging control methods provided in this application.

[0275] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A charging and discharging control method, characterized in that, include: The total power change of each battery in the photovoltaic-storage system is obtained; wherein, the photovoltaic-storage system further includes multiple inverters, each inverter being connected to at least one battery; each battery includes at least one cell; the total power change is the total change in charging power or the total change in discharging power of each battery; The percentage of power change of the battery is determined based on the battery's state of charge and rated capacity; the percentage of power change is used to indicate the percentage of charging or discharging of the battery. The power of each battery is determined based on the total power change and the percentage of power change of the battery; the power includes charging power or discharging power. The power of the battery is used to control the charging or discharging of the battery.

2. The charging and discharging control method according to claim 1, characterized in that, Determining the discharge percentage of the battery based on its state of charge and rated capacity includes: The remaining energy of the battery is the product of its state of charge and its rated capacity. Calculate the ratio of the remaining energy of the battery to the total remaining energy, and use the ratio as the discharge percentage of the battery; the total remaining energy is the sum of the remaining energy of all batteries.

3. The charging and discharging control method according to claim 2, characterized in that, Determining the discharge percentage of the battery based on its state of charge and rated capacity includes: Calculate the difference between the rated capacity of the battery and the remaining energy of the battery; The ratio of the difference to the total remaining energy is used as the charging percentage of the battery.

4. The charging and discharging control method according to claim 1, characterized in that, The total power change is the total charging power change. Based on the total power change and the percentage of power change in each battery, the power of each battery is determined, including: When it is necessary to increase the battery charging power, for each battery, the product of the total change in charging power and the charging percentage of the battery is calculated to obtain the power change of the battery in the current cycle. The sum of the battery's charging power in the previous cycle and the battery's power change in the current cycle is taken as the battery's charging power in the current cycle.

5. The charging and discharging control method according to claim 4, characterized in that, Based on the total power change and the percentage of power change in the battery, the power of each battery is determined, further including: When it is necessary to reduce the battery charging power, obtain the total charging power of all batteries; If the total charging power of all batteries is greater than or equal to the total change in charging power, then for each battery, the product of the total change in charging power and the charging percentage of the battery is calculated to obtain the power change of the battery in the current cycle. When the charging and discharging states of all batteries do not need to be consistent, the difference between the charging power of the battery in the previous cycle and the power change of the battery in the current cycle is taken as the charging power of the battery in the current cycle. When the charging and discharging states of all batteries need to remain consistent, if the charging power of a battery in the previous cycle is greater than the power change of the battery in the current cycle, the difference between the charging power of the battery in the previous cycle and the power change of the battery in the current cycle shall be taken as the charging power of the battery in the current cycle; if the charging power of a battery in the previous cycle is less than or equal to the power change of the battery in the current cycle, the charging power of the battery in the current cycle shall be set to zero.

6. The charging and discharging control method according to claim 5, characterized in that, Based on the total power change and the percentage of power change in the battery, the power of each battery is determined, further including: If the total charging power of all batteries is less than the total change in charging power, calculate the difference between the total change in charging power and the total charging power to obtain the power difference value; The product of the battery's discharge percentage and the power difference is taken as the battery's discharge power in the current cycle.

7. The charging and discharging control method according to claim 1, characterized in that, The total power change is the total discharge power change. Based on the total power change and the percentage of power change in each battery, the power of each battery is determined, including: When it is necessary to increase the battery discharge power, for each battery, the product of the total change in discharge power and the discharge percentage of the battery is calculated to obtain the power change of the battery in the current cycle. The sum of the battery's discharge power in the previous cycle and the battery's power change in the current cycle is taken as the battery's discharge power in the current cycle.

8. The charging and discharging control method according to claim 7, characterized in that, Based on the total power change and the percentage of power change in the battery, the power of each battery is determined, further including: When it is necessary to reduce the battery discharge power, obtain the total discharge power of all batteries; If the total discharge power of all batteries is greater than or equal to the total change in discharge power, then for each battery, the product of the total change in discharge power and the discharge percentage of the battery is calculated to obtain the power change of the battery in the current cycle. When the charging and discharging states of all batteries do not need to be consistent, the difference between the discharge power of the battery in the previous cycle and the power change of the battery in the current cycle is taken as the discharge power of the battery in the current cycle. When the charging and discharging states of all batteries need to remain consistent, if the discharge power of a battery in the previous cycle is greater than the power change in the current cycle, the difference between the discharge power of the battery in the previous cycle and the power change in the current cycle shall be taken as the discharge power of the battery in the current cycle; if the discharge power of a battery in the previous cycle is less than or equal to the power change in the current cycle, the discharge power of the battery in the current cycle shall be set to zero.

9. The charging and discharging control method according to claim 8, characterized in that, Based on the total power change and the percentage of power change in the battery, the power of each battery is determined, further including: If the total discharge power of all batteries is less than the total change in discharge power, calculate the difference between the total change in discharge power and the total discharge power to obtain the power difference value; The product of the battery's charging percentage and the power difference is taken as the battery's charging power in the current cycle.

10. The charging and discharging control method according to claim 1, characterized in that, The charging and discharging control method further includes: Under the condition that the preset power redistribution conditions are met, the sum of the power of each battery is taken as the total power of the battery. The new power of the battery is the product of the percentage change in battery power and the total power of the battery.

11. The charging and discharging control method according to claim 1, characterized in that, Obtain the total power change of each battery in the photovoltaic-storage system, including: Obtain the output power supplied to the power grid by the photovoltaic and energy storage system; The difference between the output power and the power demand of the power grid is taken as the total power change of each battery.

12. A converter, characterized in that, Used to perform the charge / discharge control method as described in any one of claims 1-11.

13. The converter according to claim 12, characterized in that, The DC side of the converter is connected to at least one battery, and the AC side of the converter is connected to the load.

14. The converter according to claim 13, characterized in that, The DC side of the converter is also connected to the photovoltaic module.

15. An energy manager, characterized in that, Used to perform the charge / discharge control method as described in any one of claims 1-11.

16. A junction box, characterized in that, Used to perform the charge / discharge control method as described in any one of claims 1-11.

17. A battery controller, characterized in that, Used to perform the charge / discharge control method as described in any one of claims 1-11.

18. A photovoltaic energy storage system, characterized in that, This includes the inverter as described in claim 12, the energy manager as described in claim 15, the combiner box as described in claim 16, or the battery controller as described in claim 17.

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