Photovoltaic power station time-sharing dynamic voltage optimization method and system

Abstract

The invention provides a photovoltaic power station time-sharing dynamic voltage optimization method and device, and the method comprises the steps: obtaining the open-circuit voltage Vi, j of each photovoltaic module in a plurality of original photovoltaic strings; judging whether the open-circuit voltage Vi, j of the photovoltaic module is smaller than a preset minimum threshold Vi, j, min of the open-circuit voltage of the photovoltaic module, judging the photovoltaic module of which the open-circuit voltage Vi, j is smaller than or equal to Vi, j, min as a low-voltage photovoltaic module, judging the photovoltaic module of which the open-circuit voltage Vi, j is larger than Vi, j, min as a normal-voltage photovoltaic module, and removing the low-voltage photovoltaic module from the original photovoltaic module string; according to the open-circuit voltage Vi, j of each photovoltaic module, re-stringing each photovoltaic module, and enabling the string voltage Vstr of the photovoltaic string after re-stringing to meet the preset input voltage range of the inverter; and re-stringing the photovoltaic module at an interval of T. According to the invention, the limitation of traditional fixed layout is broken, the photovoltaic system assembly string can be dynamically adjusted, and the power generation stability of the photovoltaic system is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic power stations, and in particular to a method and system for time-sharing dynamic voltage optimization of photovoltaic power stations. Background Art

[0002] Photovoltaic modules are the core power generation units of solar photovoltaic power generation. Their operating status directly impacts the power generation efficiency of the entire photovoltaic power station. However, in practice, unfavorable factors such as shading and module aging severely restrict the performance of photovoltaic modules. When some photovoltaic modules are blocked by trees, buildings, or gradually age due to long-term exposure to complex natural environments, string voltage deviation will occur. This string voltage deviation disrupts the electrical balance within the photovoltaic system and significantly reduces power generation efficiency.

[0003] Existing PV power station string systems utilize a fixed string configuration, where PV modules are connected in a specific order and pattern during installation to form a fixed string. This fixed string configuration cannot dynamically adjust to changes in the PV module's operating status or environmental conditions. Therefore, if some PV modules are obscured or age, the voltage across the entire string will be affected, leading to voltage skewness and, in turn, the overall PV system's power generation efficiency. For example, if a PV string is obscured, the operating point of the affected module will shift as the current decreases, resulting in a reduction in the output power of the entire string.

[0004] However, existing string designs and operating methods cannot dynamically adjust to changes in module performance. As a result, when the performance of some modules degrades, the performance of the entire string is affected, reducing the overall power generation efficiency of the photovoltaic system. Therefore, a method and system that can dynamically optimize the string voltage based on the real-time status of photovoltaic modules is urgently needed. Summary of the Invention

[0005] The technical problem to be solved by this application is that the existing photovoltaic power station string grouping method is fixed string grouping, which leads to shading problems and component aging problems, resulting in string voltage deviation and electrical imbalance within the photovoltaic system.

[0006] In order to solve the above problems, the present invention provides a time-sharing dynamic voltage optimization method for a photovoltaic power station, comprising: Get the open circuit voltage of each PV module in multiple original PV strings V i,j , ( i,j ) is the obtained coordinate of the photovoltaic module; Determining the open circuit voltage of the photovoltaic module V i,j Is it less than the preset minimum threshold of the PV module open circuit voltage? Vi,j,min , the open circuit voltage V i,j ≤ V i,j,min The PV modules are judged as low voltage PV modules, and the open circuit voltage V i,j > V i,j,min The photovoltaic modules are judged to be normal voltage photovoltaic modules, and the low voltage photovoltaic modules are removed from the original photovoltaic strings; According to the open circuit voltage of each photovoltaic module V i,j , each photovoltaic module is re-stringed so that the string voltage of the re-stringed photovoltaic string is V str Meet the preset input voltage range of the inverter; At intervals of time T, the photovoltaic modules are re-stringed.

[0007] Furthermore, the open circuit voltage of each photovoltaic module in the original photovoltaic string is obtained. V i,j Arrange by voltage V sorted =sort( V i,j ), the sorted values ​​are greater than the minimum threshold V i,j,min The normal voltage photovoltaic modules are connected in series, and the minimum threshold is less than V i,j,min The low-voltage photovoltaic modules should be removed or connected in strings; Preferably, the string grouping method is as follows: evenly distributing the number of photovoltaic modules according to the total number of photovoltaic modules, or adapting the strings according to voltage requirements.

[0008] Furthermore, the method for evenly distributing strings is: if the total number of photovoltaic modules N is divisible by the number of string paths K, then the number of modules per string M = N / K, and the string voltage satisfies : Furthermore, priority is given to ensuring the voltage of the original photovoltaic strings. When the input voltage range preset by the inverter is met, the remaining PV modules will continue to be grouped in descending order of voltage, and some PV modules may not be included in the string grouping.

[0009] Further, after removing the low-voltage photovoltaic components from the original photovoltaic string, the string voltage of the original photovoltaic string after removing the low-voltage photovoltaic components is calculated. V str , if the string voltage V strIf the input voltage range preset by the inverter is met, the original photovoltaic string after removing the low-voltage photovoltaic components is a re-assembled photovoltaic string.

[0010] Further, the removed multiple low-voltage photovoltaic modules are re-connected in series until the voltage of the string formed by the multiple low-voltage photovoltaic modules reconnected in series is V str If the input voltage range preset by the inverter is met, the plurality of low-voltage photovoltaic modules are reconnected in series to form a new photovoltaic string; If the voltage of the photovoltaic string after the plurality of low-voltage photovoltaic modules are removed and re-arranged, V str If the input voltage range preset by the inverter is not met, all low-voltage PV modules in the re-string will be disconnected from the inverter, and the disconnected PV modules will enter a dormant state and re-participate in the string evaluation in the next detection cycle.

[0011] Furthermore, if the plurality of normal voltage photovoltaic modules after removing the low voltage photovoltaic modules from the original photovoltaic module are connected in series to form a reorganized photovoltaic string, the string voltage V str If the input voltage range of the inverter is not met, the normal voltage photovoltaic components in the other original photovoltaic strings are disconnected from the other original photovoltaic strings, and the disconnected normal voltage photovoltaic components are reconnected in series to the reorganized photovoltaic string until the string voltage of the reorganized photovoltaic string is V str Meet the preset input voltage range of the inverter.

[0012] Furthermore, the time for re-stringing the photovoltaic components is triggered according to a preset time interval T, and the time interval T is dynamically adjusted according to a voltage deviation threshold ΔV, and re-stringing is triggered when it is detected that the string voltage deviates from the rated value by more than ΔV.

[0013] The present invention also provides a time-sharing dynamic voltage optimization system for a photovoltaic power station, for implementing the above method, the system comprising: A main controller, the main controller being electrically connected to the combiner box; Several sub-controllers electrically connected to the master controller, wherein a single sub-controller is electrically connected to at least two photovoltaic modules on a photovoltaic string, and the several sub-controllers are arranged in series; The sub-controller includes at least a voltage detection component, a switching circuit, a microcontroller, and a communication module. The voltage detection component is electrically connected to the photovoltaic component, the switching circuit is electrically connected to the microcontroller, the voltage detection component is electrically connected to the microcontroller, and the communication module is electrically connected to the microcontroller.

[0014] Furthermore, the sub-controller includes at least two voltage detection components, and a single voltage detection component is connected to a single photovoltaic component; the sub-controller includes at least two switching circuits, and a single switching circuit is connected to a single photovoltaic component, and the two switching circuits are electrically connected.

[0015] The technical effects of this application are: The photovoltaic power station time-sharing dynamic voltage optimization method provided by the present invention integrates the power electronic topology reconstruction method, breaking the traditional fixed limitations. It can dynamically adjust the power electronic structure of the photovoltaic system, accurately allocate the string voltage, and improve the power generation efficiency and stability of the photovoltaic system. It solves the problem that the existing photovoltaic power station string method is fixed, resulting in shading problems and component aging, which cause string voltage deviation and electrical imbalance within the photovoltaic system.

[0016] The photovoltaic power station time-sharing dynamic voltage optimization system provided by the present invention consists of a master controller and multiple sub-controllers. The master controller controls all sub-controllers connected to the string. The master controller is connected to the combiner box, and the master controller and sub-controllers are connected in series. The modules are connected to the sub-controllers. The sub-controllers are equipped with real-time voltage measurement of the connected modules, and communication is established between the master controller and the sub-controllers. The photovoltaic power station time-sharing dynamic voltage optimization system can be connected to two or more normally operating strings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the configuration of a photovoltaic power station time-sharing dynamic voltage optimization system in a photovoltaic power station provided by an embodiment of the present application; Figure 2 This is a schematic diagram of the circuit structure connection of the sub-controller provided in an embodiment of the present application; Figure 3 is a connection diagram of a switch circuit in an embodiment of the present invention; Figure 4 This is a schematic diagram of a photovoltaic power station string reorganization method for time-sharing dynamic voltage optimization provided by an embodiment of the present application; Figure 5 This is a schematic diagram of another photovoltaic power station time-sharing dynamic voltage optimization method re-string arrangement provided by an embodiment of the present application; Figure 6 This is another schematic diagram of re-stringing a photovoltaic power station time-sharing dynamic voltage optimization method provided by an embodiment of the present application; Figure 7 This is a schematic diagram of re-stringing another photovoltaic power station time-sharing dynamic voltage optimization method provided by an embodiment of the present application; Figure 8 This is a simplified flow chart of the time-sharing dynamic voltage optimization method for a photovoltaic power station provided by an embodiment of the present application; Description of reference numerals: 1. Main controller; 2. Sub-controller; 21. Voltage detection component; 22. Switch circuit; 221. First switch circuit; 222. Second switch circuit; 223. Third switch circuit; 23. Microcontroller; 24. Communication module; 200, combiner box; 300, original photovoltaic string; 31, photovoltaic module; 311, low-voltage photovoltaic module; 312, high-voltage photovoltaic module. DETAILED DESCRIPTION

[0018] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0019] The technical problem to be solved by the present invention is that the existing photovoltaic power station string grouping method is fixed, which leads to problems such as shading and component aging, resulting in string voltage deviation and electrical imbalance within the photovoltaic system. In order to solve the above problems, the present invention provides a photovoltaic power station time-sharing dynamic voltage optimization system, such as Figures 1-3 As shown, in one embodiment, the time-sharing dynamic voltage optimization system for a photovoltaic power station includes a master controller 1 and several sub-controllers 2. The master controller 1 is electrically connected to a combiner box 200 and is used to centrally control the entire system. It receives current, voltage, and other data transmitted by the combiner box 200, as well as information from the sub-controllers 2, and sends control instructions to each sub-controller 2. The sub-controllers 2 are electrically connected to the master controller 1. Each sub-controller 2 is electrically connected to at least two original photovoltaic modules 31 on the original photovoltaic strings 300, and the sub-controllers 2 are arranged in series.

[0020] The sub-controller includes a voltage detection component 21, a switching circuit 22, a microcontroller 23, and a communication module 24. The voltage detection component 21 is electrically connected to the photovoltaic panel 31 and measures the open-circuit voltage of the photovoltaic panel 31 in real time, transmitting the measured data to the microcontroller 23. The voltage detection component 21 can utilize a high-precision voltage sensor (such as the PD284U-9D4-3A digital voltmeter or the Oceanwide Microelectronics low-power voltage detector FS61C series) to ensure the accuracy of the measured data. The switching circuit 22 is electrically connected to the microcontroller 23 and enables or disables the photovoltaic panel 31 based on control signals sent by the microcontroller 23. The switching circuit 22 can be implemented using relays or power semiconductor devices, such as MOSFETs or IGBTs, which offer fast response times and high control accuracy. The microcontroller 23, serving as the core control unit of the sub-controller 2, is electrically connected to the voltage detection component 21, the switching circuit 22, and the communication module 24. The microcontroller 23 receives voltage data transmitted by the voltage detection component 21 and, based on instructions from the master controller 1, controls the on / off switching of the switch circuit 22 to achieve string reorganization of the photovoltaic modules. The microcontroller 23 also exchanges data with the master controller 1 via the communication module 24. The microcontroller 23 can be an embedded processor such as a single-chip microcomputer or a DSP. The communication module 24 is electrically connected to the microcontroller 23 and is used to facilitate data communication between the sub-controllers 2 and the master controller 1. The communication module 24 can utilize wired communication methods (such as RS485, CAN bus, etc.) or wireless communication methods (such as ZigBee, Wi-Fi, etc.). The appropriate communication method should be selected based on the actual conditions of the photovoltaic power station to ensure stable and reliable data transmission. The master controller can be a programmable computer. Each of the above modules is connected to a power supply module to provide continuous power supply, which will not be described in detail here.

[0021] like Figures 2 and 3 , based on the above-mentioned photovoltaic power station time-sharing dynamic voltage optimization method and system, in some preferred embodiments, the sub-controller 2 includes at least two voltage detection components 21, and a single voltage detection component 21 is connected to a single photovoltaic component 31. Each voltage detection component 21 transmits the measured open-circuit voltage data of the photovoltaic component to the microcontroller 23 of the sub-controller 2. The microcontroller 23 processes and analyzes these data so as to subsequently judge and re-string the photovoltaic components. The sub-controller 2 includes at least two switching circuits 22, and a single switching circuit 22 is connected to a single photovoltaic component 31. A one-to-one connection method is also adopted, so that each photovoltaic component can be independently connected to or removed from the photovoltaic string. The two switching circuits 22 are electrically connected through another switching circuit. This connection method can facilitate the expansion and control of the circuit. For example, when multiple photovoltaic components need to be connected or removed, the on-off sequence and combination of these switching circuits can be controlled to achieve flexible adjustment of the photovoltaic string. As Figure 3 The first switch circuit 221 is used to directly control the connection between the photovoltaic module and the main line, the second switch circuit is used to disconnect the main line on the same original photovoltaic string, and the third switch circuit 223 is used to control the connection between the photovoltaic modules of the two original photovoltaic strings 300. Figure 3 In the embodiment, the first switch circuit 221 is connected to both the positive and negative poles of the photovoltaic module 301 . Those skilled in the art may also connect the first switch circuit 221 only to either the positive or negative pole of the photovoltaic module 301 .

[0022] During system operation, the voltage detection component 21 and the switch circuit 22 work together under the control of the microcontroller 23 to achieve real-time monitoring of photovoltaic modules and dynamic stringing, including: Data acquisition and processing: The voltage detection component 21 collects the open-circuit voltage data of each photovoltaic module in real time and transmits it to the microcontroller 23. The microcontroller 23 then transmits this data to the main controller 1 through the communication module for processing and analysis to determine the status of each photovoltaic module (low voltage or normal voltage).

[0023] Re-stringing decision: The master controller 1 uses an optimization algorithm to formulate a re-stringing plan based on the status and open-circuit voltage data of each PV module and the preset input voltage range of the inverter.

[0024] Switch circuit control: The master controller 1 converts the string re-arrangement scheme into specific switch circuit control instructions. The switch circuit 22 performs on-off operations according to the received instructions to achieve the re-arrangement of the photovoltaic components.

[0025] Regular update and optimization: The system repeats the above process of data collection, processing, re-string decision-making and switching circuit control at the set time interval T to adapt to the changes in the open-circuit voltage of PV modules at different times, ensuring that the PV system is always in the best electrical balance state.

[0026] Through the above further design and optimization of the voltage detection components and switching circuits in the main controller 1 and the sub-controller 2, the time-sharing dynamic voltage optimization system of this photovoltaic power station can more accurately monitor and control the status of each photovoltaic component, realize dynamic adjustment and optimization of photovoltaic strings, and further improve the power generation efficiency and reliability of the photovoltaic power station.

[0027] Furthermore, if Figures 1 to 7 The present invention also provides a time-sharing dynamic voltage optimization method for a photovoltaic power station, which, in some embodiments, specifically includes: S100, data collection phase: obtaining the open circuit voltage of each photovoltaic module in multiple original photovoltaic strings V i,j , ( i,j) is the obtained coordinate of the photovoltaic module; In a photovoltaic power station, a voltage sensor is pre-installed on each photovoltaic module to measure the open circuit voltage of each photovoltaic module in real time. V i,j , where i represents the original PV string number and j represents the PV module number within the string. That is, (i, j) represents the coordinates of the acquired PV module. The open-circuit voltage data of each PV module is transmitted to the master controller via the data acquisition system.

[0028] For example, in a photovoltaic power station comprising 10 original photovoltaic strings 300, each of which has 15 photovoltaic modules 31, the photovoltaic power station time-sharing dynamic voltage optimization system will collect the open circuit voltage of these 150 photovoltaic modules. V i,j data and ensure its accuracy and timeliness.

[0029] S200, low voltage photovoltaic module 311 judgment and elimination stage: judging the open circuit voltage of the photovoltaic module V i,j Is it less than the preset minimum threshold of the PV module open circuit voltage? V i,j,min , the open circuit voltage V i,j ≤ V i,j,min The photovoltaic module is judged as a low-voltage photovoltaic module 311, and the open circuit voltage V i,j > V i,j,min The photovoltaic component is judged to be a normal voltage photovoltaic component 312, and the low voltage photovoltaic component 311 is removed from the original photovoltaic string; The master controller 1 receives the open circuit voltage of each photovoltaic module 31 V i,j After the data is collected, the open circuit voltage of each photovoltaic module is V i,j The lowest threshold value of the open circuit voltage of the photovoltaic module 31 is preset V i,j,min For comparison, if V i,j ≤ V i,j,min, then the photovoltaic module 31 is determined to be a low-voltage photovoltaic module 311, and the main controller 1 will record the coordinate information of these low-voltage photovoltaic modules 311. The main controller 1 sends an instruction to the sub-controller 2 connected to the original photovoltaic string 31 where the low-voltage photovoltaic module 311 is located through the communication module 24. After receiving the instruction, the sub-controller 2 controls its switch circuit 23 to remove these low-voltage photovoltaic modules 311 from the original photovoltaic string 300. In specific implementation, the switch circuit can use a relay or power semiconductor device to control its on and off to achieve the connection or removal of photovoltaic modules. For example: There are 15 PV panels in the original PV string 300, the inverter input voltage range is [360V, 540V], and the minimum threshold V i,j,min =22V, such as Figure 4 In one embodiment, the original photovoltaic string 300 has an open circuit voltage of one photovoltaic module. V i,j = 21V, the photovoltaic component is a low-voltage photovoltaic component 311, and the low-voltage photovoltaic component 311 is removed from the original photovoltaic string 300.

[0030] like Figure 5 In one embodiment, the open circuit voltage of each photovoltaic component 31 in the original photovoltaic string 300 is obtained. V i,j Finally, first sort these voltage values ​​according to the voltage size to obtain the sorted voltage sequence V sorted =sort( V i,j The sorting operation can be implemented by a common sorting algorithm, such as quick sort, merge sort, etc., to ensure that the voltage values ​​are arranged in order from small to large or from large to small.

[0031] Then, the sorted voltage sequence is compared with the preset minimum threshold of the photovoltaic module open circuit voltage. V i,j,min =22V for comparison: For sorted values ​​greater than the minimum threshold V i,j,min The PV modules are judged as normal voltage PV modules 312, which will be used for the subsequent string re-connection process. V i,j,minPV modules that are not connected to the photovoltaic string are identified as low-voltage PV modules 311. There are two ways to handle these low-voltage PV modules 311: one is to remove them from the original photovoltaic string and exclude them from subsequent string assembly. This removal can be achieved by controlling the switch circuit 23 in the sub-controller 2 to disconnect these low-voltage PV modules 311 from the photovoltaic string. The other is to string-assemble the low-voltage PV modules 311 separately. Although these modules have a lower open-circuit voltage, they can be used in separate string assembly in certain circumstances.

[0032] For the portion determined to be the normal voltage photovoltaic modules 312, the following two stringing methods are used for re-stringing.

[0033] One is to evenly distribute the number of photovoltaic panels into strings, as follows: First, determine the total number of PV panels N And the number of paths that need to be re-assembled K； If the total number of photovoltaic modules N Number of channels that can be connected in series K Divisible by M = N / K For example, if there are 100 normal voltage photovoltaic modules 312 in total and they need to be re-stringed into 5 groups, the number of modules per string is M =100 / 5=20. When stringing, select the components in order according to the sorted voltage sequence. M Components form a photovoltaic string. At the same time, it is necessary to ensure that the string voltage after stringing V str Meet the preset input voltage range of the inverter: When selecting components, you can make fine adjustments based on actual conditions. For example, if selecting a component will cause the string voltage to exceed the upper limit of the inverter input voltage range, you can choose not to select that component and instead select a suitable component from the remaining components to ensure that the string voltage is within a reasonable range.

[0034] If the total number of photovoltaic modules N Cannot be grouped together K If the value is divisible, you need to adjust it according to the actual situation. For example, you can first follow M =| N / K | (Round down) Determine the basic number of components per string, then evenly distribute the remaining components among some strings, or use other reasonable distribution methods to ensure that the number of components in each string is relatively balanced and the string voltage meets the requirements.

[0035] The other method is to adapt the string grouping according to voltage requirements, as follows: First, determine the target voltage range for each PV string based on the inverter's input voltage range and the overall design requirements of the PV power station.

[0036] Then, modules are sequentially selected from the sorted sequence of normal-voltage PV modules 312, and the sum of the voltages of the currently selected modules is calculated. When the sum of the voltages approaches the lower limit of the target voltage range, module selection continues until the sum of the voltages reaches or slightly exceeds the lower limit of the target voltage range. When the sum of the voltages approaches the upper limit of the target voltage range, module selection ceases, forming a PV string.

[0037] The above process is repeated until all normal voltage PV modules 312 are assigned to corresponding strings. During the string grouping process, the voltage characteristics of the PV modules and the input requirements of the inverter must be fully considered to ensure that the voltage of each string can meet the normal operation requirements of the inverter and maximize the power generation efficiency of the PV system.

[0038] Figure 7 This is a schematic diagram of a string sorting method in another embodiment, in which the photovoltaic modules on a plurality of original photovoltaic strings 300 are sorted as a whole and then stringed together, for example: The open circuit voltage range of a normal single battery string is 360~540V, and each battery string has 15 photovoltaic modules. The voltage of the 5 PV panels in the first battery string is 20V~22V and the voltage of the other 10 PV panels is 25V~35V; The voltage of the seven PV panels in the second battery string is 18V~22V, and the voltage of the other eight PV panels is 25V~35V; The voltage of the six PV panels in the third battery string is 18V~22V, and the voltage of the other nine PV panels is 30V~32V; The main controller 1 sorts the voltages of the photovoltaic modules detected by the sub-controller 2, and re-arranges the photovoltaic modules in the three battery strings after sorting the voltages, and sorts them from high to low voltage. After sorting, the first battery string, the second battery string, and the third battery string are re-sorted into three strings in descending order of voltage value, such as Figure 6After reordering, the 13 photovoltaic modules with voltage values ​​of 30V~35V in the original first string, second string and third string are re-stringed into one string, and the voltage of the re-organized battery string is 403V; the 14 photovoltaic modules with voltage values ​​of 25V~30V in the original first string, second string and third string are re-stringed into one string, and the voltage of the re-organized battery string is 407V; the 18 photovoltaic modules with voltage values ​​of 18V~22V in the original first string, second string and third string are re-stringed into one string, and the voltage of the re-organized battery string is 365V.

[0039] like Figure 6 In one embodiment, after the low-voltage photovoltaic modules 311 in the original photovoltaic string are removed and the remaining normal-voltage photovoltaic modules 312 are connected in series to form a reorganized photovoltaic string, the master controller collects voltage data of each normal-voltage photovoltaic module 312 in the reorganized photovoltaic string through each sub-controller. The sub-controller monitors the voltage of the normal-voltage photovoltaic modules 312 under its control in real time and uploads it to the master controller. The master controller adds the voltages of each normal-voltage photovoltaic module 312 based on the characteristics of the series circuit to obtain the string voltage of the reorganized photovoltaic string. V str .

[0040] The main controller obtains the preset input voltage range of the inverter from the system configuration file [ V min, V max ], and calculate the string voltage V str Compare with this range. V min ,≤ V str ≤ V max , it is determined that the reorganized photovoltaic string meets the input voltage requirement of the inverter and can be directly connected to the inverter for power generation; if not, the subsequent normal voltage photovoltaic component 312 adjustment process is entered.

[0041] When the voltage of the reorganized PV string does not meet the requirements, the master controller begins selecting the normal-voltage PV modules 312 from the original PV strings. This selection is primarily based on the open-circuit voltage of the normal-voltage PV modules 312 and the current operating status of the original PV strings. Normal-voltage PV modules 312 with suitable open-circuit voltages are prioritized, while minimizing the impact of removing modules on the power generation efficiency of the original PV strings. For example, normal-voltage PV modules 312 with higher open-circuit voltages and a larger number of modules and greater redundancy within the original PV strings are selected.

[0042] The master controller 1 sends instructions to the relevant sub-controllers, controlling the switching circuits within them to disconnect the selected normal-voltage PV modules 312 from their original PV strings. The sub-controllers ensure that the disconnection operation is accurate and avoids interference with other normally functioning modules. During the disconnection process, relevant information about the disconnected modules, such as their identification numbers and the original string numbers, is recorded for subsequent tracking and management.

[0043] The master controller 1 formulates a reasonable reconnection plan based on the current voltage gap in the reassembled PV string and the open-circuit voltage of the disconnected normal-voltage PV modules 312. The disconnected normal-voltage PV modules 312 are connected in series in a specific order and electrically connected to the original reassembled PV string to form a new reassembled PV string. During the connection process, the connections between the modules are ensured to be secure and reliable to avoid problems such as poor contact.

[0044] After the reconnection operation is completed, the main controller calculates the string voltage of the new reorganized photovoltaic string again V str Based on the voltage superposition principle of a series circuit, the voltage of the newly connected normal-voltage PV modules 312 is added to the voltage of the original reorganized PV string to obtain a new string voltage. This new string voltage is then compared with the inverter's preset input voltage range. If the requirements are met, the newly reorganized PV string can be connected to the inverter. If not, the above-described module screening, disconnection, and reconnection process is repeated.

[0045] Continue to refer to Figure 5~5 In one embodiment, the open circuit voltage of each photovoltaic component 31 in the original photovoltaic string 300 is obtained. V i,j After that, the PV panels are initially connected in a conventional stringing manner (e.g. according to the stringing plan in the early stage of PV power station design). However, the core goal at this time is to prioritize the voltage of each string. V str Meet the input voltage range preset by the inverter [ V min , V max ],in V min is the lower limit of the inverter input voltage, V max The upper limit of the inverter input voltage.

[0046] For example, a greedy algorithm is used for preliminary string grouping. The module with the largest open circuit voltage is selected from all photovoltaic modules as the starting module of the first string, and then other modules are added in sequence. After each addition, the sum of the voltages of the current string is calculated. When adding a module causes the string voltage to exceed Vmax When the number of PV panels exceeds 1, the addition stops, forming a string that meets the input voltage range. Repeat this process to build multiple strings until the remaining PV panels can no longer be used to form a string that meets the input voltage range.

[0047] After the initial string assembly is completed, the open circuit voltage of each photovoltaic string 31 is measured again and compared with the input voltage range preset by the inverter.

[0048] If the voltage of a string is found to be lower than V min You can try to select suitable PV modules from other unconnected PV strings and connect them to the string to increase the string voltage. When selecting modules, you should prioritize modules with high open-circuit voltages that match the voltage characteristics of the modules in the string to ensure that the string voltage meets the requirements after connection.

[0049] If the voltage of a string is higher than V max , some components need to be removed from the string. When removing components, priority should be given to components with low open-circuit voltage and minimal impact on the overall power generation efficiency of the string. At the same time, it is necessary to ensure that the string voltage after removal still meets the minimum input voltage requirement of the inverter.

[0050] After completing the priority stringing and voltage adjustment of the original photovoltaic strings, the remaining photovoltaic modules that are not involved in the string are sorted in descending order according to the open circuit voltage to obtain a voltage descending sequence. V descend =sort( V i,j ,descend). Sorting operations can also be implemented using efficient algorithms such as quick sort and merge sort.

[0051] Specifically, starting from the first component in the voltage descending sequence, components are selected in sequence for stringing. During the stringing process, the sum of the voltages of the current strings is also calculated in real time and compared with the input voltage range preset by the inverter. Unlike the initial string construction, some photovoltaic components are allowed not to participate in the stringing. When selecting components for stringing in descending voltage order, if it is found that even if the component with the largest open-circuit voltage among the remaining components is selected, the string voltage cannot reach V min , then stop stringing, and treat the components that cannot form a string that meets the input voltage range as PV components that do not participate in stringing.

[0052] In some embodiments, when obtaining the open circuit voltage of each photovoltaic module in the original photovoltaic string, V i,j Then, according to the preset minimum threshold of the open-circuit voltage of the photovoltaic module V i,j,minMake a judgment. V i,j ≤ V i,j,min The photovoltaic module is marked as a low-voltage photovoltaic module 311. This determination process can be achieved by the main controller quickly comparing the voltage data uploaded by each sub-controller. The main controller records the module information that meets the determination conditions in a specific data structure for subsequent operations.

[0053] The master controller sends instructions to each sub-controller, controlling the switching circuits within the sub-controllers to remove the components marked as low-voltage PV modules 311 from the original PV string. Specifically, each sub-controller is responsible for connecting and disconnecting PV modules within its jurisdiction. Based on instructions from the master controller, it disconnects the low-voltage PV modules 311 from the original string.

[0054] After the low-voltage PV modules 311 are removed, the master controller collects the open-circuit voltage data of the remaining PV modules. Each sub-controller uploads the remaining module voltage information to the master controller via the communication module. The master controller integrates this data into a single set containing the voltages of all remaining PV modules.

[0055] According to the connection mode of the original photovoltaic strings (such as series, parallel or series-parallel combination), calculate the string voltage of the original photovoltaic strings after removing the low-voltage photovoltaic module 311 V str If the strings are connected in series, the string voltage is equal to the sum of the open-circuit voltages of the remaining PV modules; if the strings are connected in parallel, the string voltage is equal to the same voltage value in the remaining PV modules (ideally, the voltages of parallel modules are the same); if it is a series-parallel combination, the voltage of each series branch is calculated first, and then the total string voltage is calculated based on the parallel relationship. For example, for a series string, if there is n The remaining PV modules have open circuit voltages of V 1, V 2,⋯, V n , then the string voltage V str = V 1+ V 2+⋯+ V n .

[0056] The main controller obtains the preset input voltage range of the inverter from the system configuration file or preset parameters. V min , V max] ,in V min is the lower limit of the inverter input voltage, Vmax The upper limit of the inverter input voltage. These parameters are key indicators for the normal operation of the inverter. Ensuring that the string voltage is within this range ensures that the inverter can efficiently and stably convert DC power into AC power.

[0057] The calculated string voltage V str Compare with the preset input voltage range of the inverter. V min ,≤ V str ≤ V max, it is determined that the original photovoltaic string after removing the low-voltage photovoltaic component 311 meets the input voltage requirement of the inverter. This string is the re-assembled photovoltaic string and can be directly connected to the inverter for power generation.

[0058] Reference Figure 6 ,like V str < V min , indicating that after removing the low-voltage PV module 311, the string voltage is too low and cannot meet the minimum input voltage requirement of the inverter. At this time, the system can take one of the following measures: Select appropriate modules from the spare PV module library: The PV power station can set up a spare PV module library to store some PV modules with good performance but not participating in the current string. The system selects modules with appropriate open circuit voltage from the spare library and connects them to the string according to the lack of string voltage, so that the string voltage reaches or exceeds V min .

[0059] Adjust the component allocation of other strings: If there are multiple strings, consider adjusting some components from other strings to the current string to increase the voltage of the current string. During the adjustment process, ensure that the adjusted voltage of each string still meets the input voltage range requirements of the inverter.

[0060] Mark the string as a string to be optimized and record relevant information: If the low string voltage problem cannot be immediately resolved through the above methods, the system will mark the string as a string to be optimized and record relevant information, such as the string number, current voltage, and missing voltage, for further analysis and processing.

[0061] like V str > V max, indicating that the string voltage is too high after removing the low-voltage PV module 311, which will damage the inverter. In this case, the system can take the following measures: Remove some components with higher open circuit voltage from the string: according to the open circuit voltage of each remaining photovoltaic module, remove the modules from high to low in order until the string voltage drops toV max When removing components, it is necessary to comprehensively consider the performance of the components and the overall power generation efficiency of the system, and try to remove components that have a smaller impact on power generation efficiency.

[0062] Combine the removed components with other strings: Combine the removed components with other strings with lower voltages to form new strings that meet the input voltage range, thereby achieving rational use of resources.

[0063] Reference Figure 5 In another embodiment, after the low-voltage photovoltaic modules 311 in the original photovoltaic string are removed, the main controller collects the relevant information of all the removed low-voltage photovoltaic modules 311 through each sub-controller, including but not limited to the identification number of each module, the open circuit voltage, V i,j (measured when removed), previous string position, etc. This information will be stored in the temporary data storage area of ​​the main controller to provide a data basis for subsequent re-string operations.

[0064] The collected low-voltage photovoltaic modules 311 are marked with their status, and their initial status is set to "waiting for string re-connection". At the same time, a dynamic data structure is created to record the string re-connection process, which is used to track the module combination and corresponding string voltage conditions for each string re-connection attempt.

[0065] The master controller formulates an initial string reconnection plan based on a specific strategy. For example, a simple sequential series connection method can be used to connect the discarded low-voltage PV modules 311 in series according to their identification numbers to form the first experimental string. Alternatively, the modules can be sorted in series from high to low or low to high according to their open-circuit voltages to explore the effects of different combinations on the string voltage.

[0066] After the initial string plan is formulated, the main controller calculates the string voltage of the string according to the voltage characteristics of the series circuit. V str If the string consists of n The low-voltage photovoltaic modules 311 are connected in series, and their open circuit voltages are V 1, V 2,⋯, V n , then the string voltage V str = V 1+ V 2+⋯+ V n .

[0067] Get the preset input voltage range of the inverter from the system configuration [ V min, V max ], the calculated string voltage V str Compare to this range.

[0068] like V min ,≤ V str ≤ V max , it is determined that the string formed by the reconnection of multiple low-voltage PV modules 311 in series meets the input voltage requirement of the inverter. The master controller marks the string as a "new PV string" and updates the system's string information record, including the new string's component composition, string voltage, and other information.

[0069] The master controller sends instructions to the corresponding sub-controllers, instructing them to connect the newly formed PV strings to the inverter. After connection, the system continuously monitors the operating status of the new strings, including parameters such as voltage, current, and power, to ensure their stable operation and contribution to the PV power plant.

[0070] like V str < V min ,or V str > V max , the reassembled PV strings are determined to not meet the inverter's input voltage range. The master controller sends instructions to each sub-controller, instructing them to disconnect all reassembled low-voltage PV modules 311 from the inverter. Simultaneously, these modules are marked as "dormant." In this dormant state, the modules do not participate in power generation, but the system records relevant information for subsequent processing.

[0071] At the next scheduled detection cycle, the master controller re-evaluates these dormant low-voltage PV panels 311. This evaluation process may include re-measuring the panel's open-circuit voltage (accounting for changes in panel status over time or due to environmental factors) and re-establishing the string arrangement based on the overall operation of the PV power plant at that time and the inverter's input voltage range requirements, attempting to reintegrate these panels into active PV strings.

[0072] During multiple string reconnection attempts, the master controller records the results of each attempt, including information such as the module combination, string voltage, and whether the input voltage range is met. Based on this historical data, the system can use machine learning or heuristic algorithms to optimize the string reconnection strategy. For example, by analyzing the impact of different module combinations on string voltage, the system can adjust the module selection and arrangement during subsequent string reconnections, thereby increasing the probability of successful reconnection.

[0073] Given that environmental conditions such as sunlight and temperature in PV power plants vary over time, the inverter's input voltage range requirements may also adjust based on actual operating conditions. Therefore, the system needs to dynamically adjust string re-stringing strategies and parameters. For example, during periods of strong sunlight, the open-circuit voltage of the modules may be generally higher. In this case, the upper limit of the string voltage after re-stringing can be appropriately relaxed. However, during periods of weak sunlight, the lower limit of the string voltage may need to be more strictly controlled to ensure that the strings can be properly connected to the inverter for power generation.

[0074] S300, re-string stage: according to the open circuit voltage of each photovoltaic module V i,j , each photovoltaic module is re-stringed so that the string voltage of the re-stringed photovoltaic string is V str Meet the preset input voltage range of the inverter; After removing the low-voltage photovoltaic modules 311, the master controller 1 generates the open-circuit voltages of the remaining photovoltaic modules. V i,j , re-string each photovoltaic module, the goal is to make the string voltage of the re-stringed photovoltaic string V str Meet the preset input voltage range of the inverter.

[0075] For example, a greedy algorithm can be used to sequentially select modules from the remaining PV panels, ensuring that the string voltage after each selection is as close as possible to the upper limit of the inverter input voltage range while not exceeding it. This process continues until no more suitable modules can be selected, forming a string. This process is repeated until all remaining PV panels are assigned to the appropriate strings.

[0076] The master controller sends the re-string plan to each sub-controller through the communication module. The sub-controller controls its switch circuit according to the received plan and reconnects each PV module into a new PV string.

[0077] S400, periodic re-stringing stage: re-stringing the photovoltaic modules at intervals of T; Set a time interval T, for example, 12 noon every day or other appropriate time according to local light changes. T When the system is in a low voltage state, the system automatically repeats the above process of data collection, judgment and elimination of low voltage photovoltaic modules 311, and re-stringing to adapt to the open circuit voltage changes of photovoltaic modules at different times, ensuring that the photovoltaic system is always in the best electrical balance state.

[0078] In some embodiments, the preset time interval T The setting of the time interval should take into account factors such as the light variation pattern of the area where the photovoltaic power station is located, the aging characteristics of the photovoltaic modules, and the response speed of the system. For example, in areas with frequent light changes, such as cloudy areas or areas with large temperature differences between day and night, the time interval should be T It can be set to a relatively short time, such as 15 minutes to 30 minutes, so that the system can track the impact of light changes on the voltage of photovoltaic modules in a timely manner. In areas where light changes are relatively stable, the time interval T The time interval can be appropriately extended, such as 1 to 2 hours. At the same time, the aging speed of the photovoltaic modules also needs to be considered. If the photovoltaic modules age quickly, the changes in their open circuit voltage and other parameters may be more frequent. In this case, the time interval should also be shortened appropriately. T .

[0079] When the system is initially running, the system will start at the preset time interval. T Periodically trigger the re-string operation. When each time interval arrives, the main controller collects the PV module open circuit voltage data transmitted by each sub-controller and records the current voltage value of each string. V str,k ( k These data will be used for subsequent analysis to determine whether the string voltage deviates from the rated value and for dynamic adjustment of the time interval. T basis.

[0080] In some embodiments, a rated voltage value can also be set for each photovoltaic string according to the design parameters of the photovoltaic power station and the input requirements of the inverter. V rated,k The rated voltage is the optimal operating voltage that the string can achieve under ideal light and temperature conditions, which can ensure the highest power generation efficiency of the string.

[0081] After collecting the string voltage data each time, the main controller calculates the voltage deviation of each string Δ V k =| V str,k − V rated,k |. The calculated voltage skewness Δ V k and the preset voltage skewness threshold ΔV If there is a voltage deviation of a certain string Δ V k More than Δ V , that is, Δ V k >Δ V , the re-string operation is triggered immediately without waiting for the next preset time interval T The arrival of.

[0082] When the preset time interval T No string voltage deviation from the rated value exceeding Δ V When the system dynamically adjusts the time interval according to a certain strategy T For example, exponential smoothing or statistical analysis based on historical data can be used to analyze the time interval. T Make adjustments.

[0083] Assuming the exponential smoothing method is used, let the current time interval be T n , the next time interval is T n+1 , the adjustment formula can be: T n+1 = αT n +(1− α ) T base , in α is the smoothing coefficient (0< α <1), T base It is a basic time interval and can be adjusted according to the initial settings of the system and actual operation conditions.

[0084] If the string voltage remains stable for a long time, that is, the voltage skewness is always less than Δ V , you can increase the time interval appropriately T , in order to reduce the system's calculation amount and control operation frequency, and reduce system energy consumption. On the contrary, if the string voltage fluctuates frequently, even if it does not exceed Δ V , you can also reduce the time interval appropriately T , improving the system's response speed to voltage changes.

[0085] Finally, it should be noted that unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0086] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0087] In the description of the embodiments of the present application, unless otherwise clearly specified or limited, technical terms such as "set," "provided with," "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, integration, or mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal connections between two elements or interactions between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0088] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A time-sharing dynamic voltage optimization method for a photovoltaic power station, characterized in that: include: Get the open circuit voltage of each PV module in multiple original PV strings V i,j , ( i,j ) is the obtained coordinate of the photovoltaic module; Determining the open circuit voltage of the photovoltaic module V i,j Is it less than the preset minimum threshold of the PV module open circuit voltage? V i,j,min , the open circuit voltage V i,j ≤ V i,j,min The photovoltaic module is judged as a low-voltage photovoltaic module (311), and the open circuit voltage V i,j > V i,j,min The photovoltaic component is judged to be a normal-voltage photovoltaic component (312), and the low-voltage photovoltaic component (311) is removed from the original photovoltaic string; According to the open circuit voltage of each photovoltaic module V i,j , each photovoltaic module is re-stringed so that the string voltage of the re-stringed photovoltaic string is V str Meet the preset input voltage range of the inverter; At intervals of time T, the photovoltaic modules are re-stringed.

2. The method according to claim 1, characterized in that The open circuit voltage of each photovoltaic module in the original photovoltaic string is obtained V i,j Arrange by voltage V sorted =sort( V i,j ), the sorted values ​​are greater than the minimum threshold V i,j,min The normal voltage photovoltaic components (312) are grouped into strings, and the value is less than or equal to the minimum threshold value. V i,j,min The low-voltage photovoltaic modules (311) are removed or grouped together; Preferably, the string grouping method is as follows: evenly distributing the number of photovoltaic modules according to the total number of photovoltaic modules, or adapting the strings according to voltage requirements.

3. The method according to claim 2, characterized in that The method of evenly distributing strings is: if the total number of PV modules N is divisible by the number of string paths K, then the number of modules per string M = N / K, and the string voltage satisfies :

4. The method according to claim 3, characterized in that Prioritize the string voltage of the original photovoltaic strings When the input voltage range preset by the inverter is met, the remaining PV modules will continue to be grouped in descending order of voltage, and some PV modules may not be included in the string grouping.

5. The method according to claim 1, wherein After the low-voltage photovoltaic component (311) is removed from the original photovoltaic string, the string voltage of the original photovoltaic string after removing the low-voltage photovoltaic component (311) is calculated. V str , if the string voltage V str If the input voltage range preset by the inverter is satisfied, the original photovoltaic string after removing the low-voltage photovoltaic component (311) is a re-assembled photovoltaic string.

6. The method according to claim 1, characterized in that The removed plurality of low-voltage photovoltaic modules (311) are re-connected in series until the voltage of the string formed by the re-connection of the plurality of low-voltage photovoltaic modules (311) is V str If the input voltage range preset by the inverter is satisfied, the plurality of low-voltage photovoltaic modules (311) are reconnected in series to form a new photovoltaic string; If the voltage of the photovoltaic string after the plurality of low-voltage photovoltaic components (311) are removed and re-stringed is V str If the input voltage range preset by the inverter is not met, all low-voltage photovoltaic components (311) in the re-string are disconnected from the inverter, and the disconnected photovoltaic components enter a dormant state and re-participate in the string evaluation in the next detection cycle.

7. The method according to claim 1, characterized in that If the plurality of normal voltage photovoltaic components (312) after removing the low voltage photovoltaic component (311) from the original photovoltaic string are connected in series to form a string voltage of the reorganized photovoltaic string, V str If the input voltage range preset by the inverter is not satisfied, several normal-voltage photovoltaic components (312) in other original photovoltaic strings are disconnected from the other original photovoltaic strings, and the disconnected several normal-voltage photovoltaic components (312) are reconnected in series to the reorganized photovoltaic string until the string voltage of the reorganized photovoltaic string reaches V str Meet the preset input voltage range of the inverter.

8. The method according to claim 1, characterized in that The time for re-stringing the photovoltaic components is triggered according to a preset time interval T. The time interval T is dynamically adjusted according to a voltage deviation threshold ΔV. Re-stringing is triggered when it is detected that the string voltage deviates from the rated value by more than ΔV.

9. A time-sharing dynamic voltage optimization system for a photovoltaic power station, characterized in that: include: A main controller (1), the main controller (1) being electrically connected to the combiner box (200); A plurality of sub-controllers (2) electrically connected to the master controller (1), wherein a single sub-controller (2) is electrically connected to at least two photovoltaic components (31) on photovoltaic strings (300), and the plurality of sub-controllers (2) are arranged in series; The sub-controller (2) at least includes a voltage detection component (21), a switch circuit (22), a microcontroller (23), and a communication module (24); the voltage detection component (21) is electrically connected to the photovoltaic component (31); the switch circuit (22) is electrically connected to the microcontroller (23); the voltage detection component (21) is electrically connected to the microcontroller (23); and the communication module (24) is electrically connected to the microcontroller (23).

10. The photovoltaic power station time-sharing dynamic voltage optimization system according to claim 9, characterized in that: The sub-controller (2) includes at least two voltage detection components (21), and a single voltage detection component (21) is connected to a single photovoltaic component (31); The sub-controller (2) comprises at least two switch circuits (22), a single switch circuit (22) is connected to a single photovoltaic component (31), and the two switch circuits (22) are electrically connected to each other.

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