Direct current collection system mutual aid operation control method

Abstract

The invention provides a direct current collection system and a mutual aid operation control method, and the method comprises the steps: carrying out the real-time monitoring of the output voltage and output current of each sub-array in the system, triggering a mutual aid operation mode under the condition that the output current of any sub-array is smaller than a first current threshold value, and determining a sub-array with a power gap as a demand side sub-array, power is transmitted to the demand side sub-array from the power redundant supply side sub-array, so that the demand side sub-array meets the requirement of continuous load operation, the risk of sub-array shutdown is reduced, the reliability of the system is improved, meanwhile, the framework of the direct current collection system does not need to be changed, the compatibility is high, and the cost is low. The system can be adapted to a direct current collection system comprising a photovoltaic sub-array, a wind sub-array or a hybrid wind and light sub-array, large equipment does not need to be added, and the early-stage investment cost and the later-stage operation and maintenance cost are low.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and in particular relates to a DC collection system and a mutual control method for operation. Background Technology

[0002] With the large-scale development of wind and solar power generation, large-scale wind and solar bases mostly adopt new energy DC collection systems, which operate in a multi-array distributed collection-long-distance transmission mode to reduce transmission loss and oscillation.

[0003] However, due to the strong fluctuations in wind and solar power output (e.g., photovoltaic power is affected by cloud cover and wind power is affected by wind speed changes), or due to faults in new energy subarrays, the system's input power may fall below the minimum operating threshold, leading to system shutdown and seriously affecting the continuous operation of the load and the reliability of energy supply. Summary of the Invention

[0004] This application provides a DC collection system and a mutual assistance operation control method. When the output current of any subarray is detected to be less than a first current threshold, a mutual assistance operation mode is triggered, in which the power redundant supply subarray outputs power to the demand subarray, enabling the demand subarray to meet the requirements of continuous load operation, reducing the risk of subarray shutdown, and thus improving the reliability of the system.

[0005] In a first aspect, embodiments of this application provide a method for mutual assistance operation control of a DC aggregation system. The DC aggregation system includes multiple subarrays, each subarray being connected to at least one of the remaining subarrays via a mutual assistance switch module. The method for mutual assistance operation control of the DC aggregation system includes: Real-time acquisition of the output current and output voltage of each subarray; If the output current of any subarray is less than the first current threshold, the mutual assistance operation mode is activated, and the subarray whose output current is less than the first current threshold is identified as the demand subarray. The output power of the candidate subarray is determined based on the output current and output voltage. The candidate subarray includes the subarray connected to the demand subarray. At least one candidate subarray that meets preset conditions is determined as the supplier subarray. The preset conditions include that the output power is greater than a first power threshold. Control the supply subarray to increase the output voltage, and / or control the demand subarray to decrease the output voltage; Control the closing of the mutual aid switch module located between the demand side subarray and the supply side subarray.

[0006] In some embodiments, the DC collection system mutual aid operation control method further includes: Obtain the power prediction parameters for each subarray; Based on the power prediction parameters, determine the predicted output power of each subarray; Determine the potential demand square array based on the predicted output power; Subarrays that satisfy the condition that the predicted output power is greater than the second power threshold and are connected to the potential demand subarrays are identified as candidate subarrays.

[0007] In some embodiments, determining at least one candidate subarray that meets preset conditions as the supplier subarray includes: The candidate subarrays that meet the requirements of having an output power greater than a first power threshold and a transmission distance less than or equal to a set distance threshold are determined as the supply subarrays.

[0008] In some embodiments, candidate subarrays that satisfy the condition of output power greater than a first power threshold and transmission distance less than or equal to a set distance threshold are determined as supply subarrays, including: Candidate subarrays that meet the following priority ordering based on the ratio of redundant power to transmission distance from largest to smallest: output power greater than a first power threshold and transmission distance less than or equal to a set distance threshold; the redundant power is determined based on the output power and the first power threshold. The supply subarray is determined based on the first priority ranking.

[0009] In some embodiments, candidate subarrays that satisfy the condition of output power greater than a first power threshold and transmission distance less than or equal to a set distance threshold are determined as supply subarrays, including: Based on the subarray type of the candidate subarrays, the candidate subarrays that meet the conditions of output power greater than the first power threshold and transmission distance less than or equal to the set distance threshold are sorted by a second priority; the subarray type includes single subarrays and hybrid subarrays, and the priority of hybrid subarrays is greater than that of single subarrays. The supply subarray is determined based on the second priority ranking.

[0010] In some embodiments, the DC collection system mutual aid operation control method further includes: Calculate the total demand power of the demand subarrays when the number of demand subarrays is greater than or equal to two. At least one candidate subarray that meets preset conditions is selected as the supplier subarray, including: Based on the total required power, at least one candidate subarray that meets the preset conditions is determined as the supply subarray, and the total redundant power of the supply subarray is greater than or equal to the total required power.

[0011] In some embodiments, controlling the supply subarray to increase the output voltage, and / or controlling the demand subarray to decrease the output voltage, includes: Control the output voltage of the supply array to increase the first voltage threshold; And / or, control the output voltage of the demand-side subarray to decrease to a second voltage threshold.

[0012] In some embodiments, the DC collection system mutual aid operation control method further includes: The output power supplied to the square array is determined once at a set interval; If the output power of the supply subarray is less than or equal to the first power threshold, the next priority candidate subarray is determined as the new supply subarray.

[0013] In some embodiments, the DC collection system mutual aid operation control method further includes: In the event of a failure in any subarray, disconnect the connection between the failed subarray and the DC collection system, and remove the failed subarray from the alternative subarrays.

[0014] In some embodiments, the DC collection system mutual aid operation control method further includes: If the output current of the demand-side subarray is greater than or equal to the second current threshold, the system will exit the mutual assistance operation mode. The second current threshold is greater than the first current threshold.

[0015] In some embodiments, the DC collection system mutual aid operation control method further includes: The output voltage of the control supply array is gradually reduced to the base voltage; In addition, the output voltage of the control demand subarray is gradually increased to the base voltage.

[0016] Secondly, embodiments of this application also provide a DC charging system, including: Multiple subarrays; each subarray is connected to at least one of the remaining subarrays via a mutual aid switch module; The mutual aid controller is configured to: acquire the output current and output voltage of each subarray in real time; determine to activate the mutual aid operation mode when the output current of any subarray is less than a first current threshold, and identify the subarray with the output current less than the first current threshold as the demand subarray; determine the output power of candidate subarrays based on the output current and output voltage, including subarrays connected to the demand subarray; identify at least one candidate subarray that meets preset conditions as the supply subarray, including the output power being greater than a first power threshold; control the supply subarray to increase its output voltage and control the demand subarray to decrease its output voltage; and control the mutual aid switch module located between the demand subarray and the supply subarray to close.

[0017] This application provides a DC aggregation system and a mutual assistance operation control method. By monitoring the output voltage and output current of each subarray in real time, when the output current of any subarray is less than a first current threshold, a mutual assistance operation mode is triggered, and the subarray with a power deficit is identified as the demand-side subarray. Power is then transferred from the power-redundant supply-side subarray to the demand-side subarray, enabling the demand-side subarray to meet the requirements for continuous load operation, reducing the risk of subarray shutdown, and thus improving the reliability of the system. At the same time, it does not require changes to the architecture of the DC aggregation system, has strong compatibility, and can be adapted to DC aggregation systems including photovoltaic subarrays, wind power arrays, or hybrid wind and solar subarrays. It does not require the addition of large equipment, and the initial investment cost and subsequent operation and maintenance cost are low. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a mutual assistance operation control method for a DC collection system provided in this embodiment; Figure 2 This is a schematic diagram of the structure of a DC collection system provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a mutual aid controller provided in an embodiment of this application. Detailed Implementation

[0020] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0021] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0022] To address the need for reliable power supply to loads via DC aggregation of renewable energy sources, related technologies suffer from significant technical shortcomings, making it difficult to balance reliability, economy, and efficiency requirements. For example, while adding energy storage devices such as lithium batteries can fill power gaps, this incurs high initial investment and maintenance costs, and the batteries have a lifespan of only 10 years, requiring periodic replacement and facing environmental pressures related to battery recycling. Another example is relying solely on the natural complementarity of output from different subarrays (e.g., the spatiotemporal differences between photovoltaic and wind power), lacking active control mechanisms. In extreme weather conditions (such as continuous rain or windless periods), when the output of multiple subarrays drops sharply simultaneously, the power gap cannot be compensated, resulting in insufficient reliability of load power supply.

[0023] In summary, the existing technologies cannot guarantee stable load operation without additional equipment redundancy and rapid response. There is an urgent need for a technical solution to achieve dynamic power allocation between subarrays in the mutual operation technology of new energy DC collection systems.

[0024] Based on this, this application provides a DC aggregation system and a mutual assistance operation control method. By monitoring the output voltage and output current of each subarray in real time, when the output current of any subarray is less than a first current threshold, a mutual assistance operation mode is triggered, and the subarray with a power gap is identified as the demand-side subarray. Power is then transferred from the power-redundant supply-side subarray to the demand-side subarray, enabling the demand-side subarray to meet the requirements of continuous load operation, reducing the risk of subarray shutdown, and thus improving the reliability of the system. At the same time, it does not require changes to the architecture of the DC aggregation system, has strong compatibility, and can be adapted to DC aggregation systems including photovoltaic subarrays, wind power arrays, or hybrid wind and solar subarrays. It does not require the addition of large equipment, and the initial investment cost and subsequent operation and maintenance cost are low.

[0025] The following describes a mutual control method for DC collection system provided in an embodiment of this application.

[0026] Figure 1This is a flowchart illustrating a mutual assistance operation control method for a DC aggregation system provided in an embodiment of this application. Figure 2 This is a schematic diagram of a DC collection system provided in an embodiment of this application. (Refer to...) Figure 2 The DC collection system includes multiple subarrays 101, each subarray 101 being connected to at least one of the remaining subarrays via a mutual aid switch module 102.

[0027] The subarray may include photovoltaic subarrays, wind power subarrays, and hybrid subarrays, with the hybrid subarray including both photovoltaic modules and wind power modules. The subarray may also include other new energy subarrays known to those skilled in the art, such as tidal power subarrays and hydropower subarrays, which are not limited herein.

[0028] A subarray is the smallest functional independent unit of a DC collection system, and may include power generation components and DC transformers. The DC components may include strings of photovoltaic modules or several wind turbines within a specific area. Subarrays possess independent operation, fault isolation, and local control capabilities. Multiple subarrays are connected in parallel to the upper DC collection bus to form a complete DC collection system.

[0029] As an example, each subarray 101 is connected to other subarrays 101 in the system except itself via a mutual aid switch module 102.

[0030] Reference Figure 1 The mutual assistance operation control method of the DC collection system may include the following steps: S110~S160.

[0031] S110: Real-time acquisition of the output current and output voltage of each subarray.

[0032] In this step, a current sensor can be used to collect the output current of each subarray, and a voltage sensor can be used to collect the output voltage of each subarray. In one example, by collecting the current and voltage at the output terminal of the DC transformer in each subarray as the output current and output voltage of each subarray, millisecond-level output fluctuations can be captured.

[0033] S120. If the output current of any subarray is less than the first current threshold, determine to start the mutual assistance operation mode, and identify the subarray whose output current is less than the first current threshold as the demand subarray.

[0034] The first current threshold is determined based on the rated current of the subarray. In one example, the first current threshold = k1 × rated current, where k1 is greater than 0 and less than 1, and the value of k1 is related to the load. For example, k1 can take values ​​of 0.11, 0.21, 0.31, or 0.81. The first current threshold is an additional margin on the minimum current threshold required for continuous operation of the subarray, in order to pre-identify subarrays with power deficits and prevent subarray shutdown due to judgment delays.

[0035] In this step, the output current of the subarray is compared with the first current threshold. If the output current is less than the first current threshold, it indicates that the subarray has a power deficit and its power output capacity cannot meet the requirements of continuous load operation, triggering the mutual assistance operation mode. At the same time, the subarray with the power deficit is identified as the demand-side subarray.

[0036] In one example, "determining to activate the mutual assistance operation mode when the output current of any subarray is less than a first current threshold" may include the following steps: calculating the current difference between the first current threshold and the output current of each subarray; and determining to activate the mutual assistance operation mode when the current difference is greater than 0.

[0037] S130. Determine the output power of the candidate subarray based on the output current and output voltage.

[0038] Among them, the alternative subarrays include subarrays connected to the demand subarrays.

[0039] In this step, the output power of the candidate subarray can be determined based on its output current and output voltage.

[0040] S140. Determine at least one candidate subarray that meets preset conditions as the supply subarray. The preset conditions include that the output power is greater than a first power threshold.

[0041] The first power threshold is determined based on the rated power of the subarray and is the minimum power required for the subarray to maintain stable operation. In one example, the first power threshold = k2 × rated power, where k2 is greater than 0 and less than 1, and the value of k2 is related to the load. For example, k2 can take values ​​of 0.11, 0.21, 0.31, or 0.81.

[0042] In this step, the output power of the subarray is compared with a first power threshold. If the output power is greater than the first power threshold, it indicates that the candidate subarray has redundant power and can be used as a supplier subarray to transfer power to the demand subarray, so that the demand subarray can meet the requirements of continuous load operation. All candidate subarrays that meet the preset conditions can be determined as supplier subarrays, or a portion (e.g., one or more) of the candidate subarrays can be selected as supplier subarrays.

[0043] In one example, “determining at least one candidate subarray that meets preset conditions as the supply subarray, the preset conditions including output power greater than a first power threshold” may include the following steps: calculating the difference between the output power of each candidate subarray and the first power threshold; if the difference is greater than 0, determining at least one of the candidate subarrays as the supply subarray.

[0044] S150, control the supply subarray to increase the output voltage, and / or control the demand subarray to decrease the output voltage.

[0045] Within the same DC collection system, the output voltages of the DC transformers in each subarray are essentially stable and similar. This step creates a voltage difference between the supply and demand subarrays by increasing the output voltage of the supply subarray and / or decreasing the output voltage of the demand subarray. After closing the mutual assistance switch module between the demand and supply subarrays, the voltage difference drives redundant power to flow from the supply subarray to the demand subarray.

[0046] In one embodiment, “controlling the supply subarray to increase the output voltage and / or controlling the demand subarray to decrease the output voltage” may include the following steps: controlling the output voltage of the supply subarray to increase a first voltage threshold; and / or controlling the output voltage of the demand subarray to decrease a second voltage threshold.

[0047] In this embodiment, a voltage boost command is issued to the supply subarray to increase its output voltage by a first voltage threshold, and / or a voltage decrease command is issued to the demand subarray to decrease its output voltage by a second voltage threshold. The first and second voltage thresholds may be equal or unequal. The first and second voltage thresholds can be dynamically adjusted according to the transmission distance between the supply and demand subarrays.

[0048] In one example, the base voltage is U base This indicates that the output voltage U after the supply subarray is improved. supply =U base +ΔU1, the output voltage after the demand subarray is reduced is U demand =U base -ΔU2 creates a voltage difference between the supply and demand subarrays, driving redundant power to flow from the supply subarray to the demand subarray.

[0049] In one embodiment, the mutual operation control method of the DC aggregation system may include the following steps: employing proportional-integral (PI) voltage closed-loop control for each subarray. Closed-loop control ensures that the input current / power of each load always meets the threshold requirements, ensuring continuous operation without current drops, resulting in a subarray voltage regulation response time ≤10ms, voltage fluctuation ≤±0.2%, and avoiding link voltage conflicts.

[0050] S160, control the closure of the mutual aid switch module located between the demand side subarray and the supply side subarray.

[0051] In this step, after closing the mutual assistance switch module between the demand-side subarray and the supply-side subarray, the supply-side subarray and the demand-side subarray are connected. Driven by the voltage difference, redundant power flows from the supply-side subarray to the demand-side subarray, enabling the demand-side subarray to meet the requirements of continuous load operation and reducing the risk of the demand-side subarray stopping operation.

[0052] This application also has certain advantages in terms of cost control and compatibility. It only requires adding mutual support switch modules between subarrays, without the need for large-scale equipment, resulting in lower initial investment and subsequent operation and maintenance costs. Furthermore, this application does not require changes to the architecture of the DC collection system and can be adapted to photovoltaic, wind power, or hybrid wind-solar subarrays, demonstrating strong compatibility.

[0053] This application provides a method for mutual assistance operation control of a DC aggregation system. By monitoring the output voltage and output current of each subarray in real time, when the output current of any subarray is less than a first current threshold, a mutual assistance operation mode is triggered, and the subarray with a power deficit is identified as the demand-side subarray. Power is then transferred from the power-redundant supply-side subarray to the demand-side subarray, enabling the demand-side subarray to meet the requirements for continuous load operation, reducing the risk of subarray outage, and thus improving the reliability of the system. At the same time, it does not require changes to the architecture of the DC aggregation system, has strong compatibility, and can be adapted to DC aggregation systems including photovoltaic subarrays, wind power arrays, or hybrid wind and solar subarrays. It does not require the addition of large equipment, and has low initial investment costs and low subsequent operation and maintenance costs.

[0054] In one embodiment, the mutual operation control method for the DC collection system further includes: acquiring power prediction parameters for each subarray; determining the predicted output power of each subarray based on the power prediction parameters; determining potential demand-side subarrays based on the predicted output power; and identifying subarrays that satisfy the condition that the predicted output power is greater than a second power threshold and are connected to potential demand-side subarrays as candidate subarrays.

[0055] The power prediction parameters may include historical operating data of the subarray, which may include all data known to those skilled in the art, such as irradiance and wind speed, and are not limited thereto.

[0056] In this embodiment, the power prediction parameters of each subarray can be input into a trained machine learning model. The machine learning model determines the predicted output power of each subarray based on the power prediction parameters, and identifies subarrays that may experience a sudden drop in output power in advance, i.e., potential demand-side subarrays. At the same time, based on the predicted output power and potential demand subarrays, potential supply-side subarrays are pre-screened, which narrows down the range of candidate subarrays in advance and helps to shorten the response delay time.

[0057] In one embodiment, "determining at least one candidate subarray that meets preset conditions as the supply subarray" may include the following steps: determining the candidate subarray that meets the conditions of having an output power greater than a first power threshold and a transmission distance less than or equal to a set distance threshold as the supply subarray.

[0058] In this embodiment, transmission distance is added as another factor to the selection of supplier subarrays in addition to output power. When multiple candidate subarrays simultaneously satisfy the condition that the output power is greater than a first power threshold, subarrays with transmission distances greater than a set distance threshold are excluded from the candidate subarrays, which helps to reduce transmission loss.

[0059] In one example, the candidate subarrays that meet the requirement of having an output power greater than the first power threshold can also be prioritized according to the transmission distance from shortest to longest. The subarray with the shorter transmission distance is selected as the supplier subarray, which helps to reduce transmission loss.

[0060] In some embodiments, "determining candidate subarrays that satisfy the condition of output power greater than a first power threshold and transmission distance less than or equal to a set distance threshold as supply subarrays" may include the following steps: sorting candidate subarrays that satisfy the condition of output power greater than a first power threshold and transmission distance less than or equal to a set distance threshold in descending order of the ratio of redundant power to transmission distance; and determining supply subarrays according to the first priority sorting.

[0061] The redundant power is determined based on the output power and a first power threshold. In one embodiment, the redundant power is the difference between the output power and the first power threshold, and the redundant power is greater than 0.

[0062] In this embodiment, the power is sorted according to the ratio of redundant power to transmission distance. The higher the ratio, the higher the priority and the lower the corresponding transmission loss, thus achieving precise power allocation.

[0063] In some embodiments, "determining candidate subarrays that satisfy the condition of output power greater than a first power threshold and transmission distance less than or equal to a set distance threshold as supplier subarrays" may include the following steps: sorting candidate subarrays that satisfy the condition of output power greater than a first power threshold and transmission distance less than or equal to a set distance threshold according to the subarray type of the candidate subarrays; and determining supplier subarrays according to the second priority sorting.

[0064] The subarray types include single subarrays and hybrid subarrays, with hybrid subarrays having a higher priority than single subarrays. For example, a single subarray refers to a subarray that includes only photovoltaic modules or only wind power modules, while a hybrid subarray refers to a subarray that includes both photovoltaic and wind power modules.

[0065] In this embodiment, the hybrid subarray includes multiple types of power generation components. Different power generation components can complement each other, giving the hybrid subarray a higher priority, which is beneficial to improving reliability.

[0066] It should be noted that, among the three influencing factors of output power, transmission distance, and subarray type, output power has the highest priority, transmission distance has a medium priority, and subarray type has the lowest priority.

[0067] In some embodiments, the DC collection system mutual operation control method may further include the following steps: when the number of demand-side subarrays is greater than or equal to two, calculating the total demand power of the demand-side subarrays.

[0068] In this embodiment, when there are multiple subarrays with insufficient output in the DC collection system, the total demand power of all demand subarrays is calculated, that is, the cumulative value of the demand power of all demand subarrays.

[0069] In one example, the required power of a single demand subarray can be determined based on the base voltage of the demand subarray and the current difference between the output current and the first current threshold. The cumulative value of the required power of all demand subarrays is then determined as the total required power.

[0070] In one example, the current difference between the output current of each demand subarray and a first current threshold is calculated; the sum of the current differences of all demand subarrays is determined as the cumulative current difference; and the product of the cumulative current difference and the base voltage is determined as the total demand power.

[0071] "Determining at least one candidate subarray that meets preset conditions as the supply subarray" may include the following steps: determining at least one candidate subarray that meets preset conditions as the supply subarray based on the total demand power, wherein the total redundant power of the supply subarray is greater than or equal to the total demand power.

[0072] In this embodiment, by adjusting the pulse width modulation (PWM) duty cycle of the subarray DC transformer, the output current is increased until the total redundant power of the supply subarray is greater than or equal to the total demand power of the demand matrix, thus filling the power gap of multiple demand subarrays.

[0073] In some embodiments, the DC collection system mutual assistance operation control method further includes: determining the output power of the supply subarray once at a set interval; and determining the second-priority candidate subarray as the new supply subarray when the output power of the supply subarray is less than or equal to a third power threshold.

[0074] In this embodiment, a dynamic replacement control strategy is adopted for the supply subarray. The output power of the supply subarray is refreshed every set time interval. If the output power of the current supply subarray drops sharply and falls below the third power threshold, the second-priority alternative matrix is ​​immediately activated as the supply subarray to fill the power gap. This avoids the demand subarray from shutting down due to the sharp drop in the output power of the supply subarray, which helps to improve the reliability of the DC collection system.

[0075] In one embodiment, the DC pooling system mutual operation control method may further include the following steps: in the event of a failure in any subarray, disconnecting the connection link between the faulty subarray and the DC pooling system, and deleting the faulty subarray from the alternative subarrays.

[0076] In this embodiment, when a fault is detected in any subarray, a control command is sent to the corresponding faulty subarray to disconnect the DC circuit breaker in the faulty subarray, cut off the faulty subarray link, and prevent the fault impact from spreading. Since the faulty subarray cannot operate normally and cannot provide redundant power to the demanding subarray, it is removed from the candidate subarrays to avoid mistakenly using it as a supplying subarray and causing ineffective control. It also helps to shorten the response time.

[0077] In one embodiment, the mutual assistance operation control method for the DC collection system may further include the following steps: determining to exit the mutual assistance operation mode when the output current of the demand-side subarray is greater than or equal to a second current threshold.

[0078] The second current threshold is also determined based on the rated current of the subarray. The second current threshold is greater than the first current threshold. In one example, the second current threshold = k3 × rated current, where k3 is greater than 0 and less than 1, and the value of k3 is related to the load. For example, k1 can take values ​​of 0.12, 0.22, 0.32, or 0.82. The second current threshold adds a certain margin to the minimum current threshold required for subarray operation to improve subarray stability and reduce the probability of misjudgment.

[0079] In this embodiment, if the output current of the demand-side subarray is greater than or equal to the second current threshold, it indicates that the subarray can meet the minimum current threshold requirement for subarray operation and can exit the mutual assistance operation mode.

[0080] In one embodiment, the mutual operation control method of the DC collection system may further include the following steps: controlling the output voltage of the supply subarray to gradually decrease to the base voltage; and controlling the output voltage of the demand subarray to gradually increase to the base voltage.

[0081] In this embodiment, after determining to exit the mutual assistance operation mode, a voltage reduction command is issued to the supply subarray to control the output voltage of the supply subarray to gradually decrease, reduce the dispatched power, until the output voltage is restored to the base voltage. At the same time, a voltage increase command is issued to the demand subarray to control the output voltage of the demand subarray to gradually increase to the base voltage, so as to avoid current surge.

[0082] For example, such as Figure 2 As shown, the mutual assistance operation control method for the DC collection system may include the following steps: ① High-precision monitoring: Upload optical power prediction parameters.

[0083] In this step, the power prediction parameters of each subarray are transmitted to the mutual aid controller.

[0084] ② Gap determination: Based on the optical power prediction, subarrays that may have power gaps are identified.

[0085] ③ Optimal allocation: Determine the optimal one or more suppliers based on the redundant power of each subarray and the transmission distance to the gap subarray.

[0086] ④ Voltage regulation: When an instruction is issued, the output voltage of the DC transformer on the supply side increases by ΔU1, and the voltage of the DC transformer on the demand side decreases by ΔU2, thus creating a power flow.

[0087] ⑤ Closed Interconnection: Issue commands to close two or more subarrays in a loop to form power mutual assistance.

[0088] ⑥ Exit Mechanism: When the self-generated power exceeds 0.12 pu, upload data and request to exit the mutual aid mechanism.

[0089] Based on the mutual assistance operation control method for the DC aggregation system provided in the above embodiments, this application also provides specific implementation methods for the DC aggregation system. Please refer to the following embodiments.

[0090] First see Figure 2 The DC aggregation system provided in this application includes: multiple subarrays 101 and mutual aid controller 103.

[0091] Each subarray 101 is connected to at least one of the remaining subarrays via a mutual aid switch module 102. Subarrays may include photovoltaic subarrays, wind power subarrays, and hybrid subarrays, with hybrid subarrays including both photovoltaic and wind power modules. Subarray 101 may also include other new energy subarrays known to those skilled in the art, such as tidal power subarrays and hydropower subarrays, which are not limited herein.

[0092] Subarray 101 is the smallest functional independent unit of the DC collection system, and may include power generation components and DC transformers. The DC components may include photovoltaic module strings or several wind turbines within a specific area. The subarray has independent operation, fault isolation, and local control capabilities. Multiple subarrays are connected in parallel to the upper DC collection bus to form a complete DC collection system.

[0093] The mutual aid controller 103 is configured to: acquire the output current and output voltage of each subarray 101 in real time; determine to start the mutual aid operation mode when the output current of any subarray 101 is less than a first current threshold, and identify the subarray with the output current less than the first current threshold as the demand subarray; determine the output power of the candidate subarray based on the output current and output voltage, the candidate subarray including the subarray connected to the demand subarray; identify at least one candidate subarray that meets preset conditions as the supply subarray, the preset conditions including the output power being greater than a first power threshold; control the supply subarray to increase the output voltage, and control the demand subarray to decrease the output voltage; and control the mutual aid switch module located between the demand subarray and the supply subarray to close.

[0094] In one example, the mutual aid controller 103 can be located at the dispatch center to remotely control each subarray 101 within the system.

[0095] This application provides a DC aggregation system that uses a mutual aid controller 103 to monitor the output voltage and output current of each subarray 101 in real time. When the output current of any subarray 101 is less than a first current threshold, a mutual aid operation mode is triggered, and the subarray with a power deficit is identified as the demand subarray. Power is then transferred from the power-redundant supply subarray to the demand subarray, enabling the demand subarray to meet the requirements for continuous load operation and reducing the risk of subarray 101 shutdown, thereby improving the reliability of the system. At the same time, it does not require changes to the architecture of the DC aggregation system, has strong compatibility, and can be adapted to DC aggregation systems including photovoltaic subarrays, wind power arrays, or hybrid wind and solar subarrays. It does not require the addition of large equipment, and the initial investment cost and subsequent operation and maintenance cost are low.

[0096] In one embodiment, such as Figure 2 As shown, the DC collection system also includes a DC transformer 104. The DC transformer 104 corresponds one-to-one with the subarray 101 and is used to modulate the output power. The modulated DC voltage is then transmitted to the upstream collection bus.

[0097] For example, the collection system for a photovoltaic subarray includes a photovoltaic combiner box and a DC transformer. The collection system for a wind turbine array includes a wind turbine inverter and a DC transformer.

[0098] For example, such as Figure 2As shown, the tributary collection system includes subarrays 101, a mutual aid controller 103, and a rigid load layer. Subarray 101 comprises photovoltaic subarrays, wind-electron subarrays, and hybrid wind-solar subarrays. Each subarray 101 is equipped with a DC transformer 104, voltage sensors, current sensors, and wind / solar power prediction devices. The mutual aid controller includes an acquisition module, a supplier screening module, a power allocation module, and a fault protection module, enabling parameter monitoring, strategy calculation, and command issuance. The rigid load layer includes electrolytic cells, converter valves, and IT cabinets, etc., used to receive stable power / current regulated by the mutual aid mechanism.

[0099] Figure 3 A schematic diagram of the hardware structure of the mutual aid controller provided in an embodiment of this application is shown.

[0100] The mutual aid controller may include a processor 301 and a memory 302 storing computer program instructions.

[0101] Specifically, the processor 301 may include a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0102] Memory 302 may include mass storage for data or instructions. For example, and not limitingly, memory 302 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 302 may include removable or non-removable (or fixed) media. Where appropriate, memory 302 may be internal or external to the controller. In a particular embodiment, memory 302 is a non-volatile solid-state memory.

[0103] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.

[0104] The processor 301 reads and executes computer program instructions stored in the memory 302 to implement any of the DC collection system mutual operation control methods in the above embodiments.

[0105] In one example, the mutual aid controller may also include a communication interface 303 and a bus 304. Wherein, as... Figure 3 As shown, the processor 301, memory 302, and communication interface 303 are connected through bus 304 and complete communication with each other.

[0106] The communication interface 303 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0107] Bus 304 includes hardware, software, or both, that couples components of an online data flow metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hypertext Transfer (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VESA Local Bus, VLB) bus, or other suitable buses, or a combination of two or more of these. Where appropriate, bus 304 may include one or more buses. Although specific buses are described and illustrated in the embodiments of this application, this application considers any suitable bus or interconnection.

[0108] Furthermore, in conjunction with the DC-DC pooling system mutual assistance operation control method in the above embodiments, this application embodiment can provide a computer storage medium for implementation. The computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the DC-DC pooling system mutual assistance operation control methods in the above embodiments.

[0109] This application also provides a computer program product, including a computer program that, when executed by a processor, implements any of the DC collection system mutual operation control methods described in the above embodiments.

[0110] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0111] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable-ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0112] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0113] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific operation processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A mutual assistance operation control method for a DC collection system, characterized in that, The DC collection system includes multiple subarrays, each of which is connected to at least one of the remaining subarrays via a mutual aid switch module; the method includes: Real-time acquisition of the output current and output voltage of each subarray; If the output current of any of the subarrays is less than the first current threshold, the mutual assistance operation mode is activated, and the subarray whose output current is less than the first current threshold is identified as the demand subarray. Based on the output current and the output voltage, the output power of the candidate subarray is determined, and the candidate subarray includes the subarray connected to the demand subarray; At least one candidate subarray that meets preset conditions is determined as the supply subarray, wherein the preset conditions include the output power being greater than a first power threshold. Control the supply subarray to increase the output voltage, and / or control the demand subarray to decrease the output voltage; The mutual assistance switch module located between the demand side subarray and the supply side subarray is closed.

2. The method according to claim 1, characterized in that, Also includes: Obtain the power prediction parameters for each of the subarrays; Based on the power prediction parameters, determine the predicted output power of each subarray; Based on the predicted output power, determine the potential demand subarray; The subarray that satisfies the condition that the predicted output power is greater than the second power threshold and is connected to the potential demand subarray is identified as a candidate subarray.

3. The method according to claim 1, characterized in that, At least one candidate subarray that meets preset conditions is selected as the supplier subarray, including: The candidate subarrays that satisfy the condition that the output power is greater than the first power threshold and the transmission distance is less than or equal to the set distance threshold are determined as the supply subarrays.

4. The method according to claim 3, characterized in that, The candidate subarrays that satisfy the condition that the output power is greater than the first power threshold and the transmission distance is less than or equal to a set distance threshold are determined as the supply subarrays, including: Candidate subarrays that satisfy the condition that the output power is greater than the first power threshold and the transmission distance is less than or equal to a set distance threshold are sorted by first priority in descending order of the ratio of redundant power to transmission distance; the redundant power is determined based on the output power and the first power threshold. The supply subarray is determined based on the first priority sorting.

5. The method according to claim 3, characterized in that, The candidate subarrays that satisfy the condition that the output power is greater than the first power threshold and the transmission distance is less than or equal to a set distance threshold are determined as the supply subarrays, including: Based on the subarray type of the candidate subarrays, the candidate subarrays that satisfy the condition that the output power is greater than the first power threshold and the transmission distance is less than or equal to a set distance threshold are sorted by a second priority; the subarray type includes single subarrays and hybrid subarrays, and the priority of the hybrid subarray is greater than the priority of the single subarray; The supply subarray is determined based on the second priority sorting.

6. The method according to any one of claims 1-5, characterized in that, Also includes: When the number of demand subarrays is greater than or equal to two, calculate the total demand power of the demand subarrays. The step of determining at least one candidate subarray that meets preset conditions as the supplier subarray includes: Based on the total required power, at least one candidate subarray that meets the preset conditions is determined as the supply subarray, and the total redundant power of the supply subarray is greater than or equal to the total required power.

7. The method according to any one of claims 1-5, characterized in that, The control of the supply subarray to increase the output voltage, and / or the control of the demand subarray to decrease the output voltage, includes: The output voltage of the supply subarray is increased to a first voltage threshold. And / or, control the output voltage of the demand subarray to decrease to a second voltage threshold.

8. The method according to any one of claims 1-5, characterized in that, Also includes: The output power of the supply subarray is determined once at a set interval; If the output power of the supply subarray is less than or equal to the first power threshold, the next lower priority candidate subarray is determined as the new supply subarray.

9. The method according to any one of claims 1-5, characterized in that, Also includes: In the event of a failure in any of the subarrays, the connection link between the failed subarray and the DC collection system is disconnected, and the failed subarray is removed from the alternative subarrays.

10. The method according to any one of claims 1-5, characterized in that, Also includes: If the output current of the demand-side subarray is greater than or equal to the second current threshold, the system is determined to exit the mutual assistance operation mode, where the second current threshold is greater than the first current threshold.

11. The method according to claim 10, characterized in that, Also includes: The output voltage of the supply subarray is gradually reduced to the base voltage; In addition, the output voltage of the demand-side subarray is gradually increased to the base voltage.

12. A DC collection system, characterized in that, include: Multiple subarrays; each of the subarrays is connected to at least one of the remaining subarrays via a mutual aid switch module; The mutual aid controller is configured to: acquire the output current and output voltage of each subarray in real time; determine to activate the mutual aid operation mode when the output current of any subarray is less than a first current threshold, and identify the subarray with the output current less than the first current threshold as the demand subarray; determine the output power of candidate subarrays based on the output current and the output voltage, the candidate subarrays including subarrays connected to the demand subarray; identify at least one candidate subarray that meets preset conditions as the supply subarray, the preset conditions including the output power being greater than a first power threshold; control the supply subarray to increase its output voltage, and / or control the demand subarray to decrease its output voltage; and control the mutual aid switch module located between the demand subarray and the supply subarray to close.

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