A power distribution method for an energy storage coupling system

Abstract

The application discloses a power distribution method of an energy storage coupling system, and relates to the field of energy storage systems. A direct current coupling architecture containing multiple power conversion units is constructed inside an energy storage module, so that a load can directly obtain direct current power from an energy storage battery through the power conversion units, avoiding an energy conversion link of first converting direct current power of the energy storage into alternating current power and then performing secondary rectification. Meanwhile, the first converter unit and the second converter unit are mainly used for energy interaction with a power grid or establishing a direct current side output voltage, and when the energy storage battery supplies power to the load, the direct current energy supply is directly completed through the power conversion units without passing through an alternating current link, thereby significantly reducing unnecessary alternating current-direct current conversion links. Meanwhile, in combination with a distribution strategy based on an operation mode, an on-grid state, a load carrying state and a start-stop state of a power generation unit, precise, safe and efficient energy scheduling under multi-source cooperation is realized.

Description

Technical Field

[0001] This invention relates to the field of energy storage systems, and more particularly to a power distribution method for an energy storage coupled system. Background Technology

[0002] With the rapid development of the new energy industry, the integrated application of commercial and industrial energy storage systems and electric vehicle charging facilities is becoming increasingly widespread. However, existing photovoltaic-storage-charging systems still face many challenges in actual operation. On the one hand, the traditional AC-side coupling technology route requires the DC power from the energy storage battery to be inverted into AC power through a converter, and then converted to AC-DC power by the charging module in the charging pile to meet the charging needs of electric vehicles. This dual energy conversion not only increases the complexity of the system but also leads to significant energy loss and reduces the overall energy conversion efficiency. On the other hand, the energy management system in the existing technology cannot directly intervene in the power allocation of the charging module and cannot perform fine-grained control of photovoltaic power generation, diesel power generation, and energy storage release, thus limiting the full utilization of the advantages of the photovoltaic-storage-charging system. Especially when facing complex grid state changes and diverse user needs (such as different charging priorities, grid peak and valley periods, and demand control), the existing energy management strategies are not flexible and efficient enough. Summary of the Invention

[0003] To address the problems of high energy conversion losses and low efficiency in existing photovoltaic-energy storage-charging systems due to AC-side coupling, as well as the difficulty in achieving precise power allocation, this invention proposes a power allocation method for an energy storage coupling system. The energy storage coupling system includes:

[0004] The power generation unit is connected to the power grid via an inverter;

[0005] One or more energy storage modules; the energy storage module includes a power conversion module and a first converter unit and a second converter unit respectively connected to the power grid;

[0006] The power conversion module includes multiple power conversion units, each connected to a load.

[0007] Power allocation methods include:

[0008] Based on the combination of modes and states consisting of the operating modes of each converter unit in the energy storage module, the grid connection and off-grid status of the energy storage coupling system, the load-carrying status of the energy storage coupling system to the load, and the startup status of the power generation unit, the allocation strategy corresponding to the mode and state combination is determined.

[0009] Based on the allocation strategy, the allocated power values ​​corresponding to the first converter unit and the second converter unit are determined respectively, and based on the allocated power values, power is allocated to all power conversion units in the corresponding energy storage module.

[0010] Furthermore, the combination of patterns and states includes:

[0011] Off-grid-load-excess power generation-bidirectional converter combination: When the energy storage coupling system is off-grid, the power conversion unit is connected to a load, and the output power of the power generation unit is greater than the total power request of the load, each converter unit operates in bidirectional converter mode to store electrical energy in the energy storage battery;

[0012] Grid-load-generator unit not started-unidirectional rectification combination: When the energy storage coupling system is in grid-connected state, the power conversion unit is connected to a load, and the generator unit is not started, each converter unit operates in unidirectional rectification mode to obtain power from the grid to establish its DC side output voltage and ensure the normal operation of each power conversion unit;

[0013] Grid-load-excess generation-bidirectional converter combination: When the energy storage coupling system is in grid-connected state, its power conversion unit is connected to a load, and the output power of the power generation unit is greater than the total power request of the load, each converter unit operates in bidirectional converter mode.

[0014] Off-grid-load-generator unit not started-bidirectional converter combination: When the energy storage coupling system is off-grid, its power conversion unit is connected to a load, and the generator unit is not started, each converter unit operates in bidirectional converter mode, and the energy storage battery supplies power to the load.

[0015] Furthermore, the allocation strategy includes:

[0016] A first strategy that includes a power allocation algorithm based on the state of charge of energy storage batteries and a branch power allocation algorithm;

[0017] A second strategy that includes a unidirectional rectification power allocation algorithm and a branch power allocation algorithm;

[0018] The combination of off-grid, on-load, excess power generation, and bidirectional converter corresponds to the first strategy;

[0019] The combination of grid connection, load-generating unit not started, and unidirectional rectification corresponds to the second strategy;

[0020] The combination of grid connection, load-carrying, excess power generation, and bidirectional converter corresponds to the first strategy;

[0021] The combination of off-grid, on-load, generator unit not started, and bidirectional converter corresponds to the first strategy.

[0022] Furthermore, the power conversion module also includes a first branch unit and a second branch unit;

[0023] The first branch unit includes multiple energy storage batteries and a first branch corresponding to each energy storage battery. The second branch unit includes multiple energy storage batteries and a second branch corresponding to each energy storage battery. The first branch and the second branch correspond to each other.

[0024] One end of each first branch is connected to one end of the corresponding second branch through a power conversion unit. The other end of the first branch is connected to the first converter unit and the corresponding energy storage battery. The other end of the second branch is connected to the second converter unit and the corresponding energy storage battery.

[0025] Based on the allocation strategy, the allocated power values ​​for the first and second converter units are determined respectively. Then, based on these allocated power values, power is allocated to all power conversion units within the corresponding energy storage modules, specifically as follows:

[0026] Determine the maximum allowable power of the branch units corresponding to the first and second branch units in the energy storage module;

[0027] Based on the combination of mode and state, the corresponding preset method is invoked. The preset method determines the actual allocable power of the first converter unit and the second converter unit based on the maximum allowable power of each branch unit, the total requested power of the load undertaken by each branch unit, and the allocated power values ​​of the first converter unit and the second converter unit respectively.

[0028] The actual allocatable power corresponding to the first converter unit and the second converter unit is used as input, and the power is allocated to all power conversion units in the corresponding energy storage module through the branch power allocation algorithm.

[0029] The method for calculating the allocated power value is determined based on the strategy adopted:

[0030] When the first strategy is adopted, the power allocation algorithm based on the state of charge of the energy storage battery is used to calculate the allocated power values ​​corresponding to the first converter unit and the second converter unit in the energy storage module by using the preset divisible power corresponding to the energy storage module.

[0031] When the second strategy is adopted, the power allocation values ​​corresponding to the first converter unit and the second converter unit in the energy storage module are calculated by using the preset divisible power corresponding to the energy storage module through the unidirectional rectification power allocation algorithm.

[0032] Furthermore, the maximum allowable power of the branch unit is the maximum allowable discharge power or the maximum allowable charging power of the corresponding branch unit;

[0033] The methods for obtaining the maximum allowable discharge power of each branch unit include:

[0034] For each branch unit, the maximum allowable discharge power of each energy storage battery is determined according to its state of charge, and the sum of the maximum discharge power of each energy storage battery is taken as the maximum allowable discharge power of the branch unit.

[0035] The methods for obtaining the maximum allowable charging power of each branch unit include:

[0036] For each branch unit, the maximum allowable charging power of each energy storage battery is determined according to its state of charge, and the sum of the maximum charging power of each energy storage battery is taken as the maximum allowable charging power of the branch unit.

[0037] Furthermore, the power allocation algorithm based on the state of charge of the energy storage battery is as follows:

[0038] The state of charge (SOC) of all energy storage batteries in the first branch unit and the second branch unit is obtained respectively, and their average values ​​are calculated and used as the SOC of the first converter unit and the SOC of the second converter unit respectively.

[0039] The available capacity ratios of the first and second converter units are determined respectively; for each converter unit, its available capacity ratio is the difference between its corresponding state of charge and 100%.

[0040] The preset power distribution is allocated according to the ratio of the available capacity of the two converter units.

[0041] Furthermore, the unidirectional rectified power distribution algorithm specifically includes:

[0042] When the power request values ​​of both converter units are greater than or equal to the half-power threshold, the preset divisible power is allocated to the two converter units in an equal distribution manner; wherein, the half-power threshold is equal to the preset divisible power divided by 2;

[0043] When the power request value of one converter unit is less than half the power threshold and the other is greater than or equal to half the power threshold, the converter unit with the smaller power request value is allocated its requested power, and the remaining part of the preset divisible power is allocated to the other converter unit, but not exceeding its power request value.

[0044] When the power request values ​​of both converter units are less than the half power threshold, the preset divisible power will be allocated according to the power request values ​​of the two converter units respectively.

[0045] The calculation of the power request value for each converter unit specifically includes:

[0046] Obtain the total requested power of the load undertaken by the first branch unit and the second branch unit respectively;

[0047] The total requested power of the load borne by the branch unit is compared with the current maximum allowable discharge power of the branch unit, and the smaller value is taken as the power request value of the strain gauge unit.

[0048] Furthermore, the preset methods include:

[0049] The first preset method includes:

[0050] For the first branch unit, the minimum value among the total requested load power of the first branch unit, the maximum allowable power of the branch unit corresponding to the first branch unit, and the allocated power value corresponding to the first converter unit is obtained as the actual allocable power of the first converter unit; for the second branch unit, the minimum value among the total requested load power of the second branch unit, the maximum allowable power of the branch unit corresponding to the second branch unit, and the allocated power value corresponding to the second converter unit is obtained as the actual allocable power of the second converter unit.

[0051] The second preset method includes:

[0052] The smaller of the maximum allowable discharge power of the first branch unit and the total requested power of the load undertaken by the first branch unit is determined as the actual allocable power corresponding to the first converter unit.

[0053] The smaller of the maximum allowable discharge power of the second branch unit and the total requested power of the load undertaken by the second branch unit is determined as the actual allocable power corresponding to the second converter unit.

[0054] When using the combination of off-grid-load-excess power generation-bidirectional converter, grid-connected-load-power generation unit not started-unidirectional rectifier, or grid-connected-load-excess power generation-bidirectional converter, the first preset method is used to determine the actual allocable power.

[0055] When using the combination of off-grid, on-load, generator unit not started, and bidirectional converter, the actual allocable power is determined by the second preset method.

[0056] Furthermore, the branch power allocation algorithm specifically includes:

[0057] The actual allocable power corresponding to the first converter unit is evenly distributed to each power conversion unit to obtain the first pre-allocated power.

[0058] The actual allocable power corresponding to the second converter unit is evenly distributed to each power conversion unit to obtain the second pre-allocated power.

[0059] For each power conversion unit, the smaller value between its first pre-allocated power and its second pre-allocated power is taken as the initial allocated power of that power conversion unit;

[0060] For each power conversion unit, its initial allocated power is compared with its requested power:

[0061] If the initial allocated power is greater than its requested power, the actual allocated power of the power conversion unit is set to its requested power, and the excess is taken as the remaining power contribution of the power conversion unit.

[0062] If the initial allocated power is less than or equal to its requested power, the actual allocated power of the power conversion unit is set to its initial allocated power, and its additional required power is recorded as the difference between the requested power and the initial allocated power.

[0063] The requested power of the power conversion unit is the power demand of the load connected to the power conversion unit.

[0064] Calculate the sum of the remaining power contributions of all power conversion units as the current redistributable power;

[0065] The number of power conversion units with an additional power demand greater than zero is counted as the number of additional units that need to be allocated.

[0066] Furthermore, the branch power allocation algorithm also includes:

[0067] If the redistributable power is greater than zero and the number of additional allocations required is greater than zero, then perform the redistribution operation:

[0068] The redistributable power is allocated equally to all power conversion units with additional power demand, with the allocation increment for each power conversion unit not exceeding its current additional power demand.

[0069] Based on the allocation results, update the actual allocated power, remaining power contribution, and additional power demand of each power conversion unit, and recalculate the redistributable power and the number of additional allocations required.

[0070] Repeat the redistribution operation until the redistributable power is zero, or the additional power demand of all power conversion units is zero.

[0071] Furthermore, the acquisition of the total requested power of the load undertaken by the first branch unit and the second branch unit respectively includes:

[0072] Get the total power request for the load;

[0073] Calculate the average state of charge of all energy storage batteries in the first branch unit and the second branch unit respectively;

[0074] For each branch unit, calculate the difference between its average state of charge and 100%, and multiply the difference by its corresponding maximum allowable discharge power to obtain the allocation weight factor for that branch unit.

[0075] The weighting factors of the two branch units are added together to obtain the total weighting factor;

[0076] Divide the weighting factor of each branch unit by the total weighting factor to obtain the weighting coefficient of that branch unit.

[0077] Multiply the total power request of the load by the weighting coefficient of each branch unit to obtain the total power request of the load that the first branch unit and the second branch unit should each bear.

[0078] Compared with the prior art, the present invention has at least the following beneficial effects:

[0079] (1) This invention constructs a DC-coupled architecture containing multiple power conversion units within the energy storage module, enabling the load to directly obtain DC power from the energy storage battery through the power conversion units, avoiding the energy conversion stage of first inverting the stored DC power to AC power and then performing secondary rectification. Simultaneously, the first and second converter units are mainly used for energy interaction with the grid or to establish DC-side output voltage. When the energy storage battery supplies power to the load, it does not need to go through an AC stage; it directly completes the DC energy supply through the power conversion units, significantly reducing unnecessary AC / DC conversion stages. Therefore, it effectively reduces system energy loss, improves overall energy conversion efficiency, simplifies the system structure, and enhances the operational economy and reliability in industrial and commercial photovoltaic-energy storage-charging scenarios. Furthermore, by combining allocation strategies based on operating modes, grid-connected / off-grid status, load status, and generator unit start / stop status, it achieves precise, safe, and efficient energy dispatch under multi-source collaboration.

[0080] (2) This invention constructs a combination of modes and states based on the converter operating mode, the system's grid connection and disconnection status, the load-carrying status of the load, and the startup status of the power generation unit. Based on this, a corresponding allocation strategy is determined to calculate the allocated power value, and a corresponding preset method is invoked to determine the actual allocatable power of each converter unit. Subsequently, a multi-round redistribution mechanism is used to implement refined scheduling of the power conversion unit. Therefore, even under complex grid conditions and diverse user demands (such as peak-valley arbitrage and demand control), the system can still achieve flexible, efficient, and secure energy management, overcoming the limitation in existing technologies where upper-level scheduling commands are difficult to accurately implement at the lower-level power conversion unit level.

[0081] (3) This invention employs differentiated preset methods for different operating conditions: When using the off-grid-load-power generation unit not started-bidirectional converter combination, the second preset method is used, taking the smaller of the maximum allowable discharge power of the branch unit and the total requested power of the load as the actual allocable power to ensure power supply safety; under other modes and state combinations, the first preset method is used, taking the minimum of the total requested power of the load, the maximum allowable power of the branch unit, and the allocated power value as the actual allocable power, taking into account both the physical limits of the battery and the load requirements. At the same time, the maximum allowable power of the branch unit is the maximum allowable discharge power or the maximum allowable charging power of the corresponding branch unit, so that the battery always works within the safety boundary. Thus, it not only ensures the long-term health of the energy storage battery, but also improves the response accuracy and robustness of the system in the multi-source collaborative scenario of photovoltaic, energy storage, and charging.

[0082] (4) This invention implements a closed-loop adjustment mechanism of "dual-path pre-allocation - minimum initial allocation - demand comparison - surplus recovery - multi-round redistribution" for each power conversion unit through a branch power allocation algorithm: First, the actual allocable power corresponding to the first converter unit and the second converter unit is evenly allocated to each power conversion unit to obtain two sets of pre-allocated power, and the smaller of the two values ​​for each unit is taken as the initial allocated power; then, it is compared with the requested power of the power conversion unit, and redundant power is dynamically recovered and redistributed to units with gaps, and this process is repeated until resources are exhausted or demand is met. This mechanism fully taps the collaborative potential between power conversion units, realizes on-demand and waste-free allocation of load power, and is especially suitable for power consumption scenarios with strong fluctuations and differences, such as electric vehicle charging, which significantly improves the user's energy consumption experience and the overall resource utilization rate of the system.

[0083] (5) This invention dynamically determines the corresponding allocation strategy and preset method based on the combination of modes and states constituted by the operating modes of the converter unit (including bidirectional converter mode and unidirectional rectifier mode), the grid connection and disconnection status of the energy storage coupling system, the load-carrying status of the load, and the start-up status of the power generation unit. This mechanism enables the system to adaptively adjust its operating mode according to the grid interaction requirements, load changes, and power generation output, significantly improving the scheduling flexibility and energy utilization efficiency under complex operating conditions.

[0084] (6) This invention uses a power allocation algorithm based on the state of charge of the energy storage battery or a unidirectional rectification power allocation algorithm, combined with a preset available power, to reasonably calculate the allocated power value of each converter unit: in the power allocation algorithm based on the state of charge of the energy storage battery, the preset available power is allocated according to the ratio of the available capacity of the two converter units; in the unidirectional rectification scenario, it is dynamically allocated according to the power request value of each converter unit. Thus, overcharging and over-discharging of the battery are avoided, enabling the energy storage battery to participate in power supply safely and efficiently under different charging and discharging conditions, effectively extending its cycle life. Attached Figure Description

[0085] Figure 1 This is a structural diagram of the energy storage coupling system in an embodiment of the present invention. Detailed Implementation

[0086] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0087] To address the problems of high energy conversion losses and low efficiency in existing photovoltaic-storage-charging systems due to AC-side coupling, as well as the difficulty in achieving fine-grained power allocation, this invention proposes a power allocation method for energy storage coupling systems, such as... Figure 1 As shown, the energy storage coupling system includes:

[0088] Energy management system, used to issue control signals (such as preset power distribution).

[0089] A power generation unit that is connected to the power grid via an inverter; the power generation unit includes a photovoltaic unit.

[0090] One or more energy storage modules; the energy storage module includes: a local controller, a power conversion module, and a first converter unit and a second converter unit respectively connected to the power grid; wherein:

[0091] The power conversion module includes a first branch unit, a second branch unit, and multiple power conversion units that are respectively connected to the load (a charging pile in this embodiment);

[0092] In this embodiment, there are three power conversion units, which are labeled as power conversion unit 1, power conversion unit 2 and power conversion unit 3 respectively;

[0093] The first branch unit contains multiple energy storage batteries (such as...) Figure 1 The energy storage battery 1, energy storage battery 3 and energy storage battery 5) and the first branch corresponding to each energy storage battery;

[0094] The second branch unit contains multiple energy storage batteries (e.g.) Figure 1 The first branch corresponds to each of the energy storage batteries 2, 4, and 6; the second branch corresponds to each energy storage battery.

[0095] One end of each first branch is connected to one end of the corresponding second branch through a power conversion unit; the other end of the first branch is simultaneously connected to the first converter unit and the corresponding energy storage battery; the other end of the second branch is simultaneously connected to the second converter unit and the corresponding energy storage battery.

[0096] Other external loads are also connected to the power grid.

[0097] The local controller communicates with the energy management system.

[0098] Power allocation methods, including those performed by the local controller:

[0099] Based on the combination of modes and states consisting of the operating modes of each converter unit in the energy storage module, the grid connection and off-grid status of the energy storage coupling system, the load-carrying status of the energy storage coupling system to the load, and the startup status of the power generation unit, the allocation strategy corresponding to the mode and state combination is determined.

[0100] The operating modes of the converter unit include:

[0101] The bidirectional converter mode is used to support the charging and discharging of energy storage batteries and to enable energy exchange with the grid in grid-connected mode; that is, in this mode, each converter unit can achieve bidirectional energy conversion.

[0102] Rectification mode: Converts AC power from the grid to DC power to provide power to its DC side, which can be used to power the load (via the power conversion unit) or charge the energy storage battery;

[0103] Inverter mode: The inverter unit converts its DC-side electrical energy (which can come from the discharge of the energy storage battery or the output of the generator unit) into AC power and feeds it back to the grid to achieve peak shaving, demand control or energy dispatch.

[0104] The unidirectional rectification mode is used to obtain electrical energy from the grid to establish the output voltage on the DC side of the converter unit, ensuring the normal operation of the power conversion unit;

[0105] Combinations of modes and states include:

[0106] Grid-load-generator unit not started-bidirectional converter combination: When the energy storage coupling system is in grid-connected state, the power conversion unit is connected to a load and the generator unit is not started, and the energy storage battery is allowed to participate in energy exchange, each converter unit operates in bidirectional converter mode.

[0107] Whether or not the energy storage battery is allowed to participate in energy exchange is dynamically determined by the local controller based on the energy storage battery's state of charge, health status, instructions from the energy management system, or user configuration.

[0108] Off-grid-load-excess power generation-bidirectional converter combination: When the energy storage coupling system is off-grid, the power conversion unit is connected to a load, and the output power of the power generation unit is greater than the total power request of the load, each converter unit operates in bidirectional converter mode to store electrical energy in the energy storage battery;

[0109] Grid-no-load-unidirectional rectification combination: When the energy storage coupling system is in grid-connected state, its power conversion unit is not connected to the load and has no DC power supply, each converter unit works in unidirectional rectification mode to obtain power from the grid to establish DC side output voltage and ensure the normal operation of the power conversion unit.

[0110] Grid-load-generator unit not started-unidirectional rectification combination: When the energy storage coupling system is in grid-connected state, the power conversion unit is connected to a load, the generator unit is not started, and the energy storage battery is prohibited from participating in energy exchange, each converter unit operates in unidirectional rectification mode to obtain power from the grid to establish its DC side output voltage and ensure the normal operation of each power conversion unit.

[0111] Grid-load-excess generation-bidirectional converter combination: When the energy storage coupling system is in grid-connected state, its power conversion unit is connected to a load, and the output power of the power generation unit is greater than the total power request of the load, each converter unit operates in bidirectional converter mode.

[0112] Off-grid-load-generator unit not started-bidirectional converter combination: When the energy storage coupling system is off-grid, its power conversion unit is connected to a load, and the generator unit is not started, each converter unit operates in bidirectional converter mode, and the energy storage battery supplies power to the load.

[0113] Grid-load-insufficient power generation-bidirectional converter combination: When the energy storage coupling system is in grid-connected state, its power conversion unit is connected to a load, and the output power of the power generation unit is less than the total power request of the load, each converter unit operates in bidirectional converter mode, and the load demand is met by discharging the energy storage battery, and the insufficient power is provided by the grid.

[0114] Grid-load-excess power generation-converter hybrid mode combination: When the energy storage coupling system is in grid-connected state, its power conversion unit is connected to a load, and the output power of the power generation unit is greater than the total power request of the load, in the same energy storage module, one converter unit operates in unidirectional rectification mode, and the other converter unit operates in bidirectional conversion mode.

[0115] in:

[0116] The combination of grid connection, load-carrying, generator unit not started, and bidirectional converter is used as the first mode and state combination.

[0117] Off-grid-load-excess power generation-bidirectional converter combination is used as the second mode and state combination;

[0118] The grid-connected-no-load-unidirectional rectification combination is used as the third mode and state combination;

[0119] The combination of grid connection, load-generating unit not started, and unidirectional rectification is the fourth mode and state combination.

[0120] The combination of grid connection-load-excess power generation-bidirectional converter is the fifth mode and state combination;

[0121] Off-grid - Load-generating unit not started - bidirectional converter combination is the sixth mode and state combination;

[0122] The combination of grid connection-load-insufficient power generation-bidirectional converter is the seventh mode and state combination;

[0123] The combination of grid connection-load-excess power generation-converter hybrid mode is the eighth mode and state combination.

[0124] This invention dynamically determines the corresponding allocation strategy and preset method based on the combination of modes and states constituted by the converter unit's operating mode (including bidirectional converter mode and unidirectional rectification mode), the grid connection and disconnection status of the energy storage coupling system, the load-carrying status of the load, and the startup status of the generation unit. This mechanism enables the system to adaptively adjust its operating mode according to grid interaction needs, load changes, and generation output, significantly improving dispatch flexibility and energy utilization efficiency under complex operating conditions.

[0125] Allocation strategies include:

[0126] A first strategy that includes a power allocation algorithm based on the state of charge of energy storage batteries and a branch power allocation algorithm;

[0127] A second strategy that includes a unidirectional rectification power allocation algorithm and a branch power allocation algorithm;

[0128] The grid-loaded-generator unit not started-bidirectional converter combination corresponds to the first strategy;

[0129] The combination of off-grid, on-load, excess power generation, and bidirectional converter corresponds to the first strategy;

[0130] The combination of grid connection, load-generating unit not started, and unidirectional rectification corresponds to the second strategy;

[0131] The combination of grid connection, load-carrying, excess power generation, and bidirectional converter corresponds to the first strategy;

[0132] The combination of off-grid, on-load, generator unit not started, and bidirectional converter corresponds to the first strategy.

[0133] Specifically, this invention selects a corresponding allocation strategy based on the current combination of mode and state, wherein:

[0134] (1) First Strategy: This strategy is applicable to scenarios where the converter unit operates in bidirectional converter mode. In this scenario, the system uses the preset divisible power issued by the energy management system, combined with the state of charge of the energy storage batteries in the first and second branch units, to calculate the allocated power value of each converter unit, and performs fine allocation of each power conversion unit through the branch power allocation algorithm, thereby meeting the load demand while taking into account the battery charging and discharging safety, which helps to extend the service life of the energy storage battery.

[0135] (2) Second strategy: This strategy is applicable to scenarios where the converter unit operates in unidirectional rectification mode and the power conversion unit is connected to a load. In this scenario, the system dynamically determines the allocated power value according to the power request value of each converter unit and the half-power threshold comparison rule, and completes the power allocation of the power conversion unit in combination with the branch power allocation algorithm to ensure the stability of the DC side output voltage and the normal operation of the system.

[0136] The specific strategy adopted depends on the current combination of system modes and states. Through this mechanism, the system can automatically match the appropriate allocation strategy under different operating conditions, achieving precise power regulation and efficient energy management.

[0137] Based on the allocation strategy, the allocated power values ​​corresponding to the first converter unit and the second converter unit are determined respectively, and based on the allocated power values, power is allocated to all power conversion units in the corresponding energy storage module.

[0138] Based on the allocation strategy, the allocated power values ​​for the first and second converter units are determined respectively. Then, based on these allocated power values, power is allocated to all power conversion units within the corresponding energy storage modules, specifically as follows:

[0139] Determine the maximum allowable power of the branch units corresponding to the first and second branch units in the energy storage module;

[0140] The maximum allowable power of a branch unit is the maximum allowable discharge power or the maximum allowable charging power of the corresponding branch unit;

[0141] The methods for obtaining the maximum allowable discharge power of each branch unit include:

[0142] For each branch unit, the maximum allowable discharge power of each energy storage battery is determined according to its state of charge, and the sum of the maximum discharge power of each energy storage battery is taken as the maximum allowable discharge power of the branch unit.

[0143] The methods for obtaining the maximum allowable charging power of each branch unit include:

[0144] For each branch unit, the maximum allowable charging power of each energy storage battery is determined according to its state of charge, and the sum of the maximum charging power of each energy storage battery is taken as the maximum allowable charging power of the branch unit.

[0145] Based on the combination of mode and state, the corresponding preset method is invoked. The preset method determines the actual allocable power of the first converter unit and the second converter unit based on the maximum allowable power of each branch unit, the total requested power of the load undertaken by each branch unit, and the allocated power values ​​of the first converter unit and the second converter unit respectively.

[0146] Preset methods include:

[0147] The first preset method includes:

[0148] For the first branch unit, the minimum value among the total requested load power of the first branch unit, the maximum allowable power of the branch unit corresponding to the first branch unit, and the allocated power value corresponding to the first converter unit is obtained as the actual allocable power of the first converter unit; for the second branch unit, the minimum value among the total requested load power of the second branch unit, the maximum allowable power of the branch unit corresponding to the second branch unit, and the allocated power value corresponding to the second converter unit is obtained as the actual allocable power of the second converter unit.

[0149] The second preset method includes:

[0150] The smaller of the maximum allowable discharge power of the first branch unit and the total requested power of the load undertaken by the first branch unit is determined as the actual allocable power corresponding to the first converter unit.

[0151] The smaller of the maximum allowable discharge power of the second branch unit and the total requested power of the load undertaken by the second branch unit is determined as the actual allocable power corresponding to the second converter unit.

[0152] When using the following combinations: grid-loaded-generator unit not started-bidirectional converter combination, off-grid-loaded-generator surplus-bidirectional converter combination, grid-loaded-generator unit not started-unidirectional rectifier combination, or grid-loaded-generator surplus-bidirectional converter combination, the first preset method is used to determine the actual allocable power.

[0153] When using the combination of off-grid, on-load, generator unit not started, and bidirectional converter, the actual allocable power is determined by the second preset method.

[0154] This invention employs differentiated preset methods for different operating conditions: When using an off-grid, on-load, generator unit not started, bidirectional converter combination, a second preset method is used, taking the smaller of the maximum allowable discharge power of the branch unit and the total requested load power as the actual allocable power to ensure power supply safety; under other modes and state combinations, a first preset method is used, taking the minimum of the total requested load power, the maximum allowable power of the branch unit, and the allocated power value as the actual allocable power, taking into account both battery physical limits and load requirements. Simultaneously, the maximum allowable power of the branch unit is the maximum allowable discharge power or the maximum allowable charging power of the corresponding branch unit, ensuring the battery always operates within safe boundaries. This not only guarantees the long-term health of the energy storage battery but also improves the system's response accuracy and robustness in multi-source collaborative scenarios involving photovoltaic, energy storage, and charging.

[0155] The actual allocatable power corresponding to the first converter unit and the second converter unit is used as the algorithm input. Through the branch power allocation algorithm, power is allocated to all power conversion units in the corresponding energy storage module.

[0156] The branch power allocation algorithm specifically includes:

[0157] The actual allocable power corresponding to the first converter unit is evenly distributed to each power conversion unit to obtain the first pre-allocated power.

[0158] The actual allocable power corresponding to the second converter unit is evenly distributed to each power conversion unit to obtain the second pre-allocated power.

[0159] For each power conversion unit, the smaller value between its first pre-allocated power and its second pre-allocated power is taken as the initial allocated power of that power conversion unit;

[0160] For each power conversion unit, its initial allocated power is compared with its requested power:

[0161] If the initial allocated power is greater than its requested power, the actual allocated power of the power conversion unit is set to its requested power, and the excess is taken as the remaining power contribution of the power conversion unit.

[0162] If the initial allocated power is less than or equal to its requested power, the actual allocated power of the power conversion unit is set to its initial allocated power, and its additional required power is recorded as the difference between the requested power and the initial allocated power.

[0163] The requested power of the power conversion unit is the power demand of the load connected to the power conversion unit.

[0164] Calculate the sum of the remaining power contributions of all power conversion units as the current redistributable power;

[0165] The number of power conversion units with an additional power demand greater than zero is counted as the number of additional units that need to be allocated.

[0166] Branch power allocation algorithms also include:

[0167] If the redistributable power is greater than zero and the number of additional allocations required is greater than zero, then perform the redistribution operation:

[0168] The redistributable power is allocated equally to all power conversion units with additional power demand, with the allocation increment for each power conversion unit not exceeding its current additional power demand.

[0169] Based on the allocation results, update the actual allocated power, remaining power contribution, and additional power demand of each power conversion unit, and recalculate the redistributable power and the number of additional allocations required.

[0170] Repeat the redistribution operation until the redistributable power is zero, or the additional power demand of all power conversion units is zero.

[0171] This invention employs a branch power allocation algorithm to implement a closed-loop adjustment mechanism for each power conversion unit: "dual-path pre-allocation - minimum initial allocation - demand comparison - surplus recovery - multi-round redistribution." First, the actual allocable power corresponding to the first and second converter units is evenly distributed to each power conversion unit, resulting in two sets of pre-allocated power. The smaller of the two values ​​for each unit is taken as the initial allocated power. Then, this power is compared with the requested power of the power conversion unit, dynamically recovering redundant power and redistributing it to units with power shortages. This process is repeated until resources are exhausted or demand is met. This mechanism fully leverages the collaborative potential between power conversion units, achieving on-demand, waste-free allocation of load power. It is particularly suitable for power consumption scenarios with strong fluctuations and variations, such as electric vehicle charging, significantly improving the user's energy experience and the overall system resource utilization rate.

[0172] The method for calculating the allocated power value is determined based on the strategy adopted:

[0173] When the first strategy is adopted, the power allocation algorithm based on the state of charge of the energy storage battery is used to calculate the allocated power values ​​corresponding to the first converter unit and the second converter unit in the energy storage module by using the preset divisible power corresponding to the energy storage module issued by the energy management system.

[0174] The power allocation algorithm based on the state of charge of energy storage batteries is as follows:

[0175] The state of charge (SOC) of all energy storage batteries in the first branch unit and the second branch unit is obtained respectively, and their average values ​​are calculated and used as the SOC of the first converter unit and the SOC of the second converter unit respectively.

[0176] The available capacity ratios of the first and second converter units are determined respectively; for each converter unit, its available capacity ratio is the difference between its corresponding state of charge and 100%.

[0177] The preset power distribution is allocated according to the ratio of the available capacity of the two converter units.

[0178] Taking two branch units within an energy storage module as an example, assuming the first branch unit has an average state of charge (SOC) of 70%, its available capacity ratio is 30%; and the second branch unit has an average SOC of 40%, its available capacity ratio is 60%. First, the available capacity ratios of the two branch units are added together to obtain the total available capacity ratio. Then, based on the share of each branch unit's available capacity ratio in this total available capacity ratio, the preset distributable power issued by the energy management system is allocated. Since the available capacity ratio of the second branch unit accounts for two-thirds of the total available capacity ratio, the power allocated to the second converter unit is approximately two-thirds of the preset distributable power, and the power allocated to the first converter unit is approximately one-third.

[0179] When the second strategy is adopted, the power allocation values ​​corresponding to the first converter unit and the second converter unit in the energy storage module are calculated by using the preset divisible power corresponding to the energy storage module through the unidirectional rectification power allocation algorithm.

[0180] The unidirectional rectified power distribution algorithm specifically includes:

[0181] When the power request values ​​of both converter units are greater than or equal to the half-power threshold, the preset divisible power is allocated to the two converter units in an equal distribution manner; wherein, the half-power threshold is equal to the preset divisible power divided by 2;

[0182] When the power request value of one converter unit is less than half the power threshold and the other is greater than or equal to half the power threshold, the converter unit with the smaller power request value is allocated its requested power, and the remaining part of the preset divisible power is allocated to the other converter unit, but not exceeding its power request value.

[0183] When the power request values ​​of both converter units are less than the half power threshold, the preset divisible power will be allocated according to the power request values ​​of the two converter units respectively.

[0184] This invention utilizes a power allocation algorithm based on the state of charge (SBC) of the energy storage battery or a unidirectional rectification power allocation algorithm, combined with a preset available power, to rationally calculate the allocated power value for each converter unit. In the SBC-based power allocation algorithm, the preset available power is allocated according to the ratio of the available capacity of the two converter units. In the unidirectional rectification scenario, the power is dynamically allocated based on the power request value of each converter unit. This avoids overcharging and over-discharging of the battery, enabling the energy storage battery to participate in power supply safely and efficiently under different charging and discharging conditions, effectively extending its cycle life.

[0185] The calculation of the power request value for each converter unit specifically includes:

[0186] The total requested power of the loads undertaken by the first branch unit and the second branch unit is obtained through the energy management system.

[0187] The total requested power of the load borne by the branch unit is compared with the current maximum allowable discharge power of the branch unit, and the smaller value is taken as the power request value of the strain gauge unit.

[0188] The acquisition of the total requested power of the loads undertaken by the first branch unit and the second branch unit respectively includes:

[0189] Get the total power request for the load;

[0190] Calculate the average state of charge of all energy storage batteries in the first branch unit and the second branch unit respectively;

[0191] For each branch unit, calculate the difference between its average state of charge and 100%, and multiply the difference by its corresponding maximum allowable discharge power to obtain the allocation weight factor for that branch unit.

[0192] The weighting factors of the two branch units are added together to obtain the total weighting factor;

[0193] Divide the weighting factor of each branch unit by the total weighting factor to obtain the weighting coefficient of that branch unit.

[0194] Multiply the total power request of the load by the weighting coefficient of each branch unit to obtain the total power request of the load that the first branch unit and the second branch unit should each bear.

[0195] The following is a detailed explanation of power allocation based on different combinations of modes and states in various scenarios:

[0196] I. Application Scenario 1:

[0197] The converter unit operates in bidirectional converter mode.

[0198] The grid-connected and off-grid states of the energy storage coupling system are: grid-connected operation state.

[0199] Power conversion unit: operates under load.

[0200] The startup status of the power generation unit is: not started (i.e., the energy storage coupling system currently has no photovoltaic power generation or other forms of power generation input).

[0201] Energy storage batteries are allowed to participate in energy exchange.

[0202] Therefore, the mode and state combination is: grid-connected - under load - generator unit not started - bidirectional converter combination.

[0203] Under this combination, the maximum allowable power of each branch unit under each converter unit is taken as the maximum allowable discharge power of the corresponding branch unit, which is used to limit the output power of the converter unit to not exceed the battery's safe discharge capacity.

[0204] Under this combination of pattern and state, the first strategy is adopted:

[0205] 1. Power allocation algorithm based on the state of charge of energy storage batteries:

[0206] Based on the state of charge of the energy storage batteries in the corresponding branches of each converter unit, calculate the proportion of available capacity (i.e., the difference between 100% and the average state of charge), and allocate the preset distributable power to each converter unit according to this proportion.

[0207] 2. Branch power allocation algorithm:

[0208] After determining the actual allocable power of the first converter unit and the second converter unit, the actual allocable power is evenly distributed to each power conversion unit to obtain two sets of pre-allocated power. For each power conversion unit, the smaller value of its two sets of pre-allocated power is taken as the initial allocated power. Combined with the requested power of the load connected to the power conversion unit, the actual allocated power of each power conversion unit is finally determined through a multi-round residual power recovery and redistribution mechanism.

[0209] It should be noted that, under this combination of mode and state, the actual allocable power is determined by the first preset method.

[0210] Using the above strategy, under the combination of grid connection-load-generator unit not started-bidirectional converter, the following can be achieved:

[0211] Precise power control: Dynamically adjust power allocation based on demand management commands, the state of charge of the energy storage battery, and the power request from the power conversion unit.

[0212] High-efficiency energy utilization: Reduce redundant power waste and improve the overall energy efficiency of the system;

[0213] Extending battery life: A state-of-charge (POC)-based allocation strategy can prevent overcharging and over-discharging of the battery, thereby improving system safety and reliability.

[0214] II. Application Scenario 2:

[0215] Mode and state combination: grid-connected - load-carrying - excess generation - bidirectional converter combination.

[0216] In this application scenario, the converter unit operates in a bidirectional converter mode, meaning that each converter unit has the ability to both rectify and invert energy; the energy storage coupling system operates in a grid-connected state; the power conversion unit connects to the outside and drives the load (including powering electric vehicle charging piles); the power generation unit starts up and generates more electrical energy than the current load demand.

[0217] Under this combination, the maximum allowable power of each branch unit under each converter unit is taken as the maximum allowable charging power of the corresponding branch unit, which is used to limit the input power of the converter unit from not exceeding the battery's safe charging capacity.

[0218] Furthermore, under this combination, a first strategy is employed to safely and efficiently store excess electrical energy from the power generation unit into the energy storage battery, while simultaneously meeting the load's power demand. The actual allocable power is determined through a first preset method to ensure that the battery remains within a safe operating range during charging.

[0219] III. Application Scenario 3:

[0220] Mode and state combination: grid-connected - no-load - unidirectional rectification combination.

[0221] In this configuration, the converter units operate in unidirectional rectification mode; the energy storage coupling system is grid-connected; the power conversion unit is not connected to a load; and the power conversion unit has no DC power supply. At this time, each converter unit obtains AC power from the grid, rectifies it, and establishes a DC output voltage to ensure the normal standby or startup preparation of the power conversion unit.

[0222] Since there is no load, the total requested power is zero, and the system does not need to perform complex power allocation calculations. The maximum allowable power of the branch unit can be set according to the system's standby requirements, or it can be set to zero by default. This mode is mainly used to maintain the system's basic operating conditions, rather than for energy dispatching or battery charging and discharging.

[0223] IV. Application Scenario 4:

[0224] Mode and state combination: Off-grid - On-load - Excess power generation - Bidirectional converter combination.

[0225] In this application scenario, the converter unit operates in bidirectional converter mode; the energy storage coupling system operates off-grid; the power conversion unit is connected to the outside and drives the load; and the power generation unit starts up and generates more electrical energy than the current load demand.

[0226] Under this combination, the maximum allowable power of each branch unit under each converter unit is taken as the maximum allowable charging power of the corresponding branch unit, which is used to limit the input power of the converter unit from not exceeding the battery's safe charging capacity.

[0227] The first strategy is used for power allocation.

[0228] The actual allocatable power is determined by a first preset method.

[0229] V. Application Scenario 5:

[0230] Mode and state combination: grid-connected - load-generating unit not started or insufficient power generation - unidirectional rectification combination.

[0231] In this application scenario, the converter unit operates in unidirectional rectification mode; the energy storage coupling system is grid-connected; the power conversion unit is connected to a load; and the generator unit is not started or its output power is insufficient to meet the load demand. At this time, the energy storage coupling system obtains electrical energy from the grid through the converter unit, and after rectification, provides DC power to the power conversion unit to support the normal operation of the power conversion unit and the load.

[0232] In this configuration, the maximum allowable power of each branch unit is taken as its maximum allowable charging power or maximum allowable discharging power (specifically, based on the current energy exchange direction of the energy storage battery, the corresponding maximum allowable charging power (if charging) or maximum allowable discharging power (if discharging) is taken) to ensure that the battery does not exceed the safety boundary when participating in energy exchange (such as auxiliary power supply). It should be noted that in unidirectional rectification mode, the converter unit is only responsible for absorbing active power from the grid to maintain the DC-side output voltage and does not have the ability to feed power to the grid or directly control the charging and discharging of the energy storage battery; the charging and discharging behavior of the energy storage battery is autonomously coordinated by the local controller on the DC side through the power conversion unit.

[0233] The energy storage coupling system obtains electrical energy from the grid in a unidirectional rectification mode to meet the power requirements of the total load.

[0234] In this combination of mode and state, the second strategy is used for power allocation.

[0235] The actual allocatable power is determined by a first preset method.

[0236] VI. Application Scenario 6:

[0237] Mode and state combination: grid-connected - load-in-insufficient generator unit - bidirectional converter combination.

[0238] In this application scenario, the converter unit operates in bidirectional converter mode; the energy storage coupling system is in grid-connected state; the power conversion unit is connected to a load; the power generation unit has been started, but its output power is less than the total power request of the load.

[0239] Under this combination, the maximum allowable power of each branch unit is the maximum allowable discharge power of its corresponding energy storage battery, which is used to constrain the battery discharge power to not exceed the safety limit.

[0240] Under this combination, the first strategy is used for power allocation.

[0241] The actual allocatable power is determined by a first preset method.

[0242] Through this strategy, the energy storage coupling system can simultaneously utilize the discharge of the energy storage battery and the power replenishment from the grid to jointly meet the power demand of the load, ensuring power supply continuity and system stability.

[0243] VII. Application Scenario 7:

[0244] Mode and state combination: Grid-connected-load-excess generation-converter hybrid mode combination.

[0245] It should be noted that the power conversion unit integrates a bidirectional isolated DC / DC converter to achieve bidirectional power flow and voltage matching between the first and second branch units. This DC / DC converter has independent power regulation capabilities, and can distribute power between the first and second branches according to power commands issued by the local controller, while maintaining the stability of the DC voltage on both sides. Therefore, when the first and second converter units operate in different operating modes (e.g., the first converter unit is in unidirectional rectification mode, and the second converter unit is in bidirectional conversion mode), the bidirectional isolated DC / DC converter in the power conversion unit can dynamically balance the power and voltage between the two branches, avoiding circulating currents or system instability caused by differences in converter output characteristics. Based on this, the local controller can issue operating mode commands to the first and second converter units respectively, thereby supporting mixed operating modes of converter units within the same energy storage module.

[0246] In this application scenario, the energy storage coupling system operates in a grid-connected state; the power conversion unit connects to the outside and drives the load; the power generation unit starts up and generates more electrical energy than the current load demand; the converter unit operates in a hybrid mode: one converter unit operates in unidirectional rectification mode and only performs unidirectional rectification operation; the other converter unit operates in bidirectional conversion mode and has the ability to perform both rectification and inversion bidirectional energy flow.

[0247] Under this combination, the maximum allowable power of each branch unit is determined according to its energy flow direction:

[0248] For a converter unit operating in bidirectional converter mode, if its corresponding branch is in a charging state, the maximum allowable power is taken as the maximum allowable charging power of that branch; if it is in a discharging state (such as participating in demand regulation), the maximum allowable discharging power is taken.

[0249] For converter units operating in unidirectional rectification mode, they only obtain power from the grid and do not actively control the charging and discharging of the energy storage battery. The maximum allowable power of the branch units connected to them is determined according to the actual energy exchange direction: if the branch unit participates in charging, the maximum allowable charging power is taken; if it participates in discharging, the maximum allowable discharging power is taken; if it does not participate in energy exchange, it is set to zero, in order to ensure that the energy storage battery always operates within the safety boundary.

[0250] In this hybrid mode, the local controller independently applies corresponding allocation algorithms to the two converter units: for units operating in bidirectional converter mode, a power allocation algorithm based on the state of charge of the energy storage battery is used; for units operating in unidirectional rectification mode, a unidirectional rectification power allocation algorithm is used; finally, the scheduling of the power conversion units is completed through a unified branch power allocation algorithm, wherein:

[0251] Power allocation algorithm based on the state of charge of energy storage batteries: For converter units in bidirectional converter mode, the charging or discharging power of each converter unit is reasonably allocated according to the state of charge level of the energy storage battery corresponding to each converter unit, so as to ensure that the energy storage system operates in the optimal state and extend battery life.

[0252] Unidirectional rectification power allocation algorithm: Used for converter units in unidirectional rectification mode, it dynamically adjusts the power allocation method according to the power request value of each converter unit to ensure the efficient operation of the system under different load requirements.

[0253] The actual power allocation for each power conversion unit is still determined by the branch power allocation algorithm.

[0254] Through the above strategies, under the combined grid-load-excess generation-converter hybrid mode, the energy storage coupling system can achieve precise power control. Based on demand management commands, the state of charge of the energy storage battery, and the power requests of each power conversion unit, it can dynamically coordinate the power allocation of converter units in different operating modes; effectively improve energy utilization efficiency, reduce redundant power waste; enhance system operation flexibility and dynamic response capability, and ensure stable power supply to loads and electric vehicle charging piles.

[0255] The actual allocatable power is determined by a first preset method.

[0256] VIII. Application Scenario 8:

[0257] Mode and state combination: Off-grid - Loaded - Generator unit not started - Bidirectional converter combination.

[0258] In this application scenario, the energy storage coupling system operates in an off-grid state; the power generation unit is not started (no photovoltaic or other power generation input); the power conversion unit is connected to a load; each converter unit operates in bidirectional converter mode, relying on the energy storage battery to supply power to the load.

[0259] Under this combination, the actual allocable power is determined by the second preset method, and the power is allocated using the first strategy.

[0260] In this way, in extreme conditions where there is no power grid or power generation, priority can be given to ensuring continuous power supply to the load, while avoiding over-discharge of the energy storage battery, thus improving the off-grid autonomy and emergency power supply reliability of the energy storage coupling system.

[0261] This invention constructs a DC-coupled architecture within the energy storage module, consisting of a first branch unit, a second branch unit, and multiple power conversion units. This allows the load to directly obtain DC power from the energy storage battery through the power conversion units, avoiding the energy conversion process of first inverting the stored DC power to AC power and then performing secondary rectification. Simultaneously, the first and second converter units are primarily used for energy interaction with the grid or to establish DC-side output voltage. When the energy storage battery supplies power to the load, it directly provides DC energy through the power conversion units without needing an AC stage, significantly reducing unnecessary AC / DC conversion steps. This effectively reduces system energy loss, improves overall energy conversion efficiency, simplifies the system structure, and enhances the operational economy and reliability in commercial and industrial photovoltaic-energy storage-charging scenarios. Furthermore, by combining allocation strategies based on operating modes, grid-connected / off-grid status, load status, and generator unit start / stop status, precise, safe, and efficient energy dispatch under multi-source collaboration is achieved.

[0262] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0263] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0264] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0265] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A power allocation method for an energy storage coupling system, characterized in that, The energy storage coupling system includes: The power generation unit is connected to the power grid via an inverter; One or more energy storage modules; the energy storage module includes a power conversion module and a first converter unit and a second converter unit respectively connected to the power grid; The power conversion module includes multiple power conversion units that are respectively connected to the load; The power conversion module further includes a first branch unit and a second branch unit; The first branch unit includes multiple energy storage batteries and a first branch corresponding to each energy storage battery. The second branch unit includes multiple energy storage batteries and a second branch corresponding to each energy storage battery. The first branch and the second branch correspond to each other. One end of each first branch is connected to one end of the corresponding second branch through a power conversion unit. The other end of the first branch is connected to the first converter unit and the corresponding energy storage battery. The other end of the second branch is connected to the second converter unit and the corresponding energy storage battery. The power allocation method includes: Based on the combination of modes and states formed by the operating modes of each converter unit in the energy storage module, the grid connection and off-grid status of the energy storage coupling system, the load-carrying status of the energy storage coupling system to the load, and the startup status of the power generation unit, the allocation strategy corresponding to the combination of modes and states is determined. Based on the allocation strategy, the allocated power values ​​corresponding to the first converter unit and the second converter unit are determined respectively, and based on the allocated power values, power is allocated to all power conversion units within the corresponding energy storage module; specifically: Determine the maximum allowable power of the branch units corresponding to the first and second branch units in the energy storage module; Based on the combination of modes and states, the corresponding preset method is invoked. The preset method determines the actual allocatable power of the first converter unit and the second converter unit based on the maximum allowable power of each branch unit, the total requested power of the load undertaken by each branch unit, and the allocated power values ​​of the first converter unit and the second converter unit. Using the actual allocatable power corresponding to the first and second converter units as input, the branch power allocation algorithm is used to allocate power to all power conversion units within the corresponding energy storage module.

2. The power allocation method for an energy storage coupling system according to claim 1, characterized in that, The combination of modes and states includes: Off-grid-load-excess power generation-bidirectional converter combination: When the energy storage coupling system is off-grid, the power conversion unit is connected to a load, and the output power of the power generation unit is greater than the total power request of the load, each converter unit operates in bidirectional converter mode to store electrical energy in the energy storage battery; Grid-load-generator unit not started-unidirectional rectification combination: When the energy storage coupling system is in grid-connected state, the power conversion unit is connected to a load, and the generator unit is not started, each converter unit operates in unidirectional rectification mode to obtain power from the grid to establish its DC side output voltage and ensure the normal operation of each power conversion unit; Grid-load-excess generation-bidirectional converter combination: When the energy storage coupling system is in grid-connected state, its power conversion unit is connected to a load, and the output power of the power generation unit is greater than the total power request of the load, each converter unit operates in bidirectional converter mode. Off-grid-load-generator unit not started-bidirectional converter combination: When the energy storage coupling system is in an off-grid state, its power conversion unit is connected to a load, and the generator unit is not started, each converter unit operates in bidirectional converter mode, and the energy storage battery supplies power to the load.

3. The power distribution method for an energy storage coupling system according to claim 2, characterized in that, The allocation strategy includes: A first strategy that includes a power allocation algorithm based on the state of charge of energy storage batteries and a branch power allocation algorithm; A second strategy that includes a unidirectional rectifier power allocation algorithm and a branch power allocation algorithm; The method for calculating the allocated power value is determined based on the strategy adopted: When the first strategy is adopted, the power allocation algorithm based on the state of charge of the energy storage battery is used to calculate the power allocation values ​​corresponding to the first converter unit and the second converter unit in the energy storage module by using the preset divisible power corresponding to the energy storage module. When the second strategy is adopted, the power allocation values ​​corresponding to the first converter unit and the second converter unit in the energy storage module are calculated by using the preset divisible power corresponding to the energy storage module through the unidirectional rectification power allocation algorithm. The off-grid-load-excess power generation-bidirectional converter combination corresponds to the first strategy; The grid-load-generator unit not started-unidirectional rectification combination corresponds to the second strategy; The grid-load-excess power generation-bidirectional converter combination corresponds to the first strategy; The off-grid-load-generator unit not started-bidirectional converter combination corresponds to the first strategy.

4. The power allocation method for an energy storage coupling system according to claim 3, characterized in that, The maximum allowable power of the branch unit is the maximum allowable discharge power or the maximum allowable charging power of the corresponding branch unit; The methods for obtaining the maximum allowable discharge power of each branch unit include: For each branch unit, the maximum allowable discharge power of each energy storage battery is determined according to its state of charge, and the sum of the maximum discharge power of each energy storage battery is taken as the maximum allowable discharge power of the branch unit. The methods for obtaining the maximum allowable charging power of each branch unit include: For each branch unit, the maximum allowable charging power of each energy storage battery is determined according to its state of charge, and the sum of the maximum charging power of each energy storage battery is taken as the maximum allowable charging power of the branch unit.

5. The power allocation method for an energy storage coupling system according to claim 4, characterized in that, The power allocation algorithm based on the state of charge of the energy storage battery is as follows: The state of charge (SOC) of all energy storage batteries in the first branch unit and the second branch unit is obtained respectively, and their average values ​​are calculated and used as the SOC of the first converter unit and the SOC of the second converter unit respectively. The available capacity ratios of the first and second converter units are determined respectively; for each converter unit, its available capacity ratio is the difference between its corresponding state of charge and 100%. The preset divisible power is allocated according to the ratio of the available capacity of the two converter units.

6. The power distribution method for an energy storage coupling system according to claim 5, characterized in that, The unidirectional rectification power allocation algorithm specifically includes: When the power request values ​​of both converter units are greater than or equal to the half-power threshold, the preset divisible power is allocated to the two converter units in an equal distribution manner; wherein, the half-power threshold is equal to the preset divisible power divided by 2; When the power request value of one converter unit is less than half the power threshold and the other is greater than or equal to half the power threshold, the converter unit with the smaller power request value is allocated its requested power, and the remaining part of the preset divisible power is allocated to the other converter unit, but not exceeding its power request value. When the power request values ​​of both converter units are less than half the power threshold, the preset divisible power is allocated according to the power request values ​​of the two converter units respectively. The calculation of the power request value for each converter unit specifically includes: Obtain the total requested power of the load undertaken by the first branch unit and the second branch unit respectively; The total requested power of the load borne by the branch unit is compared with the current maximum allowable discharge power of the branch unit, and the smaller value is taken as the power request value of the strain gauge unit.

7. The power distribution method for an energy storage coupling system according to claim 4, characterized in that, The preset method includes: The first preset method includes: For the first branch unit, the minimum value among the total requested load power of the first branch unit, the maximum allowable power of the branch unit corresponding to the first branch unit, and the allocated power value corresponding to the first converter unit is obtained as the actual allocable power of the first converter unit; for the second branch unit, the minimum value among the total requested load power of the second branch unit, the maximum allowable power of the branch unit corresponding to the second branch unit, and the allocated power value corresponding to the second converter unit is obtained as the actual allocable power of the second converter unit. The second preset method includes: The smaller of the maximum allowable discharge power of the first branch unit and the total requested power of the load undertaken by the first branch unit is determined as the actual allocable power corresponding to the first converter unit. The smaller of the maximum allowable discharge power of the second branch unit and the total requested power of the load undertaken by the second branch unit is determined as the actual allocable power corresponding to the second converter unit. When using the combination of off-grid-load-excess power generation-bidirectional converter, grid-connected-load-power generation unit not started-unidirectional rectifier, or grid-connected-load-excess power generation-bidirectional converter, the first preset method is used to determine the actual allocable power. When using the combination of off-grid, on-load, generator unit not started, and bidirectional converter, the actual allocable power is determined by the second preset method.

8. The power allocation method for an energy storage coupling system according to claim 6, characterized in that, The branch power allocation algorithm specifically includes: The actual allocable power corresponding to the first converter unit is evenly distributed to each power conversion unit to obtain the first pre-allocated power. The actual allocable power corresponding to the second converter unit is evenly distributed to each power conversion unit to obtain the second pre-allocated power. For each power conversion unit, the smaller value between its first pre-allocated power and its second pre-allocated power is taken as the initial allocated power of that power conversion unit; For each power conversion unit, its initial allocated power is compared with its requested power: If the initial allocated power is greater than its requested power, the actual allocated power of the power conversion unit is set to its requested power, and the excess is taken as the remaining power contribution of the power conversion unit. If the initial allocated power is less than or equal to its requested power, the actual allocated power of the power conversion unit is set to its initial allocated power, and its additional required power is recorded as the difference between the requested power and the initial allocated power. The requested power of the power conversion unit is the power demand of the load connected to the power conversion unit; Calculate the sum of the remaining power contributions of all power conversion units as the current redistributable power; The number of power conversion units with an additional power demand greater than zero is counted as the number of additional units that need to be allocated.

9. The power distribution method for an energy storage coupling system according to claim 8, characterized in that, The branch power allocation algorithm also includes: If the redistributable power is greater than zero and the number of additional allocations required is greater than zero, then perform a redistribution operation: The redistributable power is allocated equally to all power conversion units with additional power demand, with the allocation increment for each power conversion unit not exceeding its current additional power demand. Based on the allocation results, update the actual allocated power, remaining power contribution, and additional power demand of each power conversion unit, and recalculate the redistributable power and the number of additional allocations required. Repeat the redistribution operation until the redistributable power is zero, or the additional power demand of all power conversion units is zero.

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