A photovoltaic regulation method and system based on contribution cost-effectiveness

Abstract

The application discloses a photovoltaic regulation method based on contribution cost ratio, and has the characteristics that the method comprises the following steps: S1, obtaining operation parameters of a plurality of photovoltaic nodes connected to a power distribution line, wherein the operation parameters comprise electrical distance, reactive voltage sensitivity, adjustable reactive power margin, topological influence and photovoltaic output fluctuation factor; S2, inputting the operation parameters into a reactive power contribution cost ratio model to obtain reactive power contribution cost ratio; and S3, sorting the photovoltaic nodes according to the reactive power contribution cost ratio from high to low and dividing the photovoltaic nodes into a plurality of control partitions. The method improves the consumption capacity and voltage support capacity of a mountainous power distribution network to distributed photovoltaic, and provides an efficient solution which takes into account power grid safety and user interests for dealing with the end voltage fluctuation problem under the background of high proportion of photovoltaic access in the future.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a photovoltaic control method and system based on contribution-cost ratio. Background Technology

[0002] Mountainous power distribution networks commonly suffer from problems such as long power supply distances, weak grid structures, and significant voltage drops at the ends, which are particularly pronounced during power transfer operations. When feeders transfer power, phenomena such as equipment overload, severely low voltage at the ends, and degraded power quality often occur, affecting users' normal electricity consumption.

[0003] With the increasing scale of distributed photovoltaic (PV) grid integration in rural power distribution networks, PV inverters have the ability to provide reactive power support and, when necessary, reduce active power to improve voltage, providing a new technical approach to solving the problem of low voltage at the end of the grid.

[0004] However, existing photovoltaic inverters lack prioritization when regulating and improving voltage issues. When reactive power regulation capacity is insufficient, existing technologies often simply include all nodes that can be reduced in the reduction range, or only sort them by sensitivity, without considering the balance between the effect of unit active power reduction on the end voltage improvement and the cost of reduction. This may result in excessive total power curtailment and a degraded user experience. Summary of the Invention

[0005] To address the aforementioned shortcomings, the present invention aims to propose a photovoltaic regulation method and system based on contribution-cost ratio, thereby solving the current problem of being unable to balance grid security and user interests when low voltage issues occur.

[0006] To achieve this objective, the present invention adopts the following technical solution: a photovoltaic control method based on contribution-performance ratio, comprising the following steps: S1: Obtain the operating parameters of multiple grid-connected photovoltaic nodes on the distribution line. The operating parameters include electrical distance, reactive voltage sensitivity, adjustable reactive margin, topological influence, and photovoltaic output fluctuation factor. S2: Input the operating parameters into the reactive power contribution cost-effectiveness model to obtain the reactive power contribution cost-effectiveness; S3: Sort the photovoltaic nodes from high to low according to their reactive power contribution cost-effectiveness and divide them into multiple control zones; S4: Monitor the voltage of the end node in real time. When the end voltage is lower than the set threshold, call up the reactive power regulation capacity of the photovoltaic nodes in the order of partitions until the end voltage is restored to the normal range. If the reactive power regulation capacity of all photovoltaic nodes is insufficient to restore the end voltage, then execute step S5. Step S5: Based on the cost-effectiveness of active power contribution, prioritize calling the node with the lowest active power reduction cost for active power transfer in order to minimize the total power curtailment.

[0007] Preferably, N distributed photovoltaic power sources connected to the grid sequentially on the line are taken as photovoltaic nodes i. In step S1, the electrical distance is defined as the equivalent electrical distance from photovoltaic node i to the end node. Among them, electrical distance , representing the equivalent impedance of the line between photovoltaic node i and the downstream photovoltaic node i-1. This represents the set of line segments from photovoltaic node i to terminal node 0; The step of obtaining reactive voltage sensitivity in step S1 is as follows: divide the voltage change of the end node by the reactive power change of a single photovoltaic node i. The adjustable reactive power margin in step S1 is: ,in Grid connection limits reactive power cap. , This represents the rated apparent power of the photovoltaic inverter corresponding to the i-th photovoltaic node. This represents the real-time active power output of the i-th photovoltaic node; The definition of topological influence in step S1 is as follows: ,in This represents the number of downstream controllable user nodes of the i-th photovoltaic node, and N is the total number of user nodes under the distribution line; The preferred reactive power contribution cost-effectiveness model is expressed as follows: ; in These are the coefficients for topological influence, electrical distance, and fluctuation influence factor, respectively. These are the normalized reactive voltage sensitivity, adjustable reactive margin, topological influence, electrical distance, and photovoltaic output fluctuation factor, respectively.

[0008] Preferably, the specific steps of step S4 are as follows: Step S41: Construct the processing set ; Step S42: Store the control partition with the highest reactive power contribution cost-effectiveness in the processing set; Step S43: Calculate the maximum end voltage increase limit within the processing set, and determine whether the maximum end voltage increase limit is greater than the end gap voltage. If it is greater, proceed to step S44; if it is less, proceed to step S42. The formula for obtaining the maximum upper limit of the terminal voltage increase is as follows: ; Step S44: Based on the current processing set Perform total reactive power demand estimation: ; Combine the current processing set The photovoltaic nodes are arranged in descending order of reactive power contribution cost-effectiveness to form an adjustment sequence; Starting from the first node in the sequence, reactive power is allocated sequentially, prioritizing nodes with higher rankings, within the available reactive power margin. The reactive power output must be within the specified range, and the output reactive power cannot exceed the total reactive power demand. And update the end gap voltage after each call. until If the value is less than or equal to 0, stop calling the photovoltaic node.

[0009] Preferably, the specific steps of step S5 are as follows: Step S51: Calculate the residual voltage gap after reactive power regulation , ,in For low voltage threshold, The end gap voltage updated for all photovoltaic nodes after step S44; Step S52: In the processing set The photovoltaic nodes with a maximum active power reduction of 0 are removed from the pool to obtain the candidate set; Step S53: Define the active power voltage rise sensitivity as: the voltage change at the end node divided by the active power change per unit of a single photovoltaic node i; The active power voltage rise sensitivity was used instead of the reactive power voltage rise sensitivity to calculate the active power contribution cost-effectiveness of photovoltaic nodes in the candidate pool. ,in , Normalized active power boost sensitivity; Step S54: Sort all photovoltaic nodes in the candidate set from largest to smallest according to their active power contribution cost-effectiveness, forming an active power reduction queuing sequence; Step S55: Calculate the voltage contribution that the j-th photovoltaic node can provide under the maximum allowable reduction in the active power reduction queuing sequence. , , This represents the maximum permissible active power reduction for the j-th photovoltaic node. Step S56: Determine voltage contribution Is it greater than or equal to the residual voltage gap? If it is less than the current maximum allowable active power reduction of the photovoltaic node, then the residual voltage gap is updated. Then, call the next photovoltaic node to re-execute step S55. If it is greater than or equal to the active power reduction, obtain the active power reduction amount based on the active power voltage rise sensitivity of the current photovoltaic node, and end the adjustment.

[0010] A photovoltaic control system based on contribution-performance ratio, using the aforementioned photovoltaic control method based on contribution-performance ratio, includes: The parameter acquisition module is used to acquire the operating parameters of multiple grid-connected photovoltaic nodes on the distribution line. The operating parameters include electrical distance, reactive voltage sensitivity, adjustable reactive power margin, topological influence, and photovoltaic output fluctuation factor. The cost-effectiveness calculation module is used to input the operating parameters into the reactive power contribution cost-effectiveness model to obtain the reactive power contribution cost-effectiveness of each photovoltaic node. The partitioning and sorting module is used to sort photovoltaic nodes from high to low according to their reactive power contribution cost-effectiveness and divide the photovoltaic nodes into multiple control partitions. The reactive power regulation module is used to monitor the voltage of the end node in real time. When the end voltage is lower than the set threshold, the reactive power regulation capacity of the photovoltaic node is called in sequence according to the partition order until the end voltage returns to the normal range. The active power regulation module is used to prioritize the node with the lowest active power reduction cost for active power transfer when the reactive power regulation capacity of all photovoltaic nodes is insufficient to restore the end voltage, based on the cost-effectiveness of active power contribution, in order to minimize the total power curtailment.

[0011] Preferably, in the parameter acquisition module, N distributed photovoltaic power sources connected to the grid in sequence on the line are taken as photovoltaic node i; The electrical distance is the equivalent electrical distance from photovoltaic node i to the end node; the reactive voltage sensitivity is the ratio of the voltage change at the end node to the reactive power change per unit amount at a single photovoltaic node i. The adjustable reactive power margin is determined based on the rated apparent power of the photovoltaic inverter and the real-time active power output of the photovoltaic node. The topological influence is determined based on the ratio of the number of downstream controllable user nodes of photovoltaic node i to the total number of user nodes under the distribution line. The photovoltaic power output fluctuation factor is the ratio of the standard deviation to the mean of the active power output of the photovoltaic access node within a specified time window.

[0012] Preferably, the cost-effectiveness calculation module is equipped with a reactive power contribution cost-effectiveness model. This model combines the coefficients of topological influence, electrical distance, and fluctuation influence factor, as well as the normalized reactive voltage sensitivity, adjustable reactive power margin, topological influence, electrical distance, and photovoltaic power output fluctuation factor to calculate the reactive power contribution cost-effectiveness.

[0013] Preferably, the reactive power control module specifically performs the following: Construct a processing set and store the control partition with the highest reactive power contribution cost-effectiveness into the processing set; Calculate the maximum upper limit of the terminal voltage increase within the processing set, and determine whether the upper limit is greater than the terminal gap voltage. If it is not satisfied, continue to add the next control zone to the processing set. If the conditions are met, the total reactive power demand of the current processing set is estimated. The photovoltaic nodes in the processing set are arranged in descending order of reactive power contribution cost-effectiveness to form an adjustment sequence. Reactive power output is allocated sequentially starting from the first node in the sequence. Reactive power is output within the available reactive power margin and does not exceed the total reactive power demand. The end gap voltage is updated after each call until the end gap voltage is less than or equal to 0 and the call is stopped.

[0014] Preferably, the active power control module specifically performs the following: Calculate the residual voltage gap after reactive power regulation; remove photovoltaic nodes with a maximum active power reduction of 0 from the processing set to obtain the candidate set; The ratio of the voltage change at the end node to the unit change in active power of a single photovoltaic node i is used as the active power voltage rise sensitivity. The active power contribution cost-effectiveness of photovoltaic nodes in the candidate pool is calculated using the active power voltage rise sensitivity. The photovoltaic nodes in the candidate set are sorted from largest to smallest according to their active power contribution cost-effectiveness to form an active power reduction queuing sequence. Calculate the voltage contribution that each photovoltaic node can provide under the maximum allowable active power reduction in turn. If the voltage contribution is less than the residual voltage gap, call the maximum allowable active power reduction of the current node and update the residual voltage gap, and continue to call the next node. If the residual voltage gap requirement is met, the active power reduction amount is determined based on the current node's active power voltage rise sensitivity, and the voltage adjustment is completed.

[0015] One of the above technical solutions has the following advantages or beneficial effects: by optimizing the control strategy, it improves the ability of mountain power grid to absorb distributed photovoltaic power and the voltage support capability, and provides an efficient solution that takes into account both grid security and user interests to deal with the problem of end voltage fluctuation in the context of high proportion of photovoltaic access in the future. Attached Figure Description

[0016] Figure 1 This is a flowchart of one embodiment of the method of the present invention.

[0017] Figure 2 This is a schematic diagram of the structure of one embodiment of the system of the present invention. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] like Figures 1-2 As shown, a photovoltaic control method based on contribution-cost ratio includes the following steps: S1: Obtain the operating parameters of multiple grid-connected photovoltaic nodes on the distribution line. The operating parameters include electrical distance, reactive voltage sensitivity, adjustable reactive margin, topological influence, and photovoltaic output fluctuation factor. S2: Input the operating parameters into the reactive power contribution cost-effectiveness model to obtain the reactive power contribution cost-effectiveness; the reactive power contribution cost-effectiveness is used to characterize the ratio between the contribution of unit reactive power regulation to the improvement of terminal voltage and the cost of power output fluctuation; S3: Sort the photovoltaic nodes from high to low according to their reactive power contribution cost-effectiveness and divide them into multiple control zones; for example, the top 30% of photovoltaic nodes are used as the priority zone, the middle 40% are used as the intermediate buffer zone, and the remaining 30% are used as the upstream backup zone.

[0022] S4: Monitor the voltage of the end node in real time. When the end voltage is lower than the set threshold, call up the reactive power regulation capacity of the photovoltaic nodes in the order of partitions until the end voltage is restored to the normal range. If the reactive power regulation capacity of all photovoltaic nodes is insufficient to restore the end voltage, then execute step S5. Step S5: Based on the cost-effectiveness of active power contribution, prioritize calling the node with the lowest active power reduction cost for active power transfer in order to minimize the total power curtailment.

[0023] First, step S1 comprehensively collects operating parameters of each photovoltaic node on the distribution line, including electrical distance, reactive power voltage sensitivity, adjustable reactive power margin, topological influence, and photovoltaic output fluctuation factor. These parameters comprehensively reflect the inherent attributes of each photovoltaic node in multiple dimensions, such as spatial location, regulation capability, and impact on grid stability. Then, in step S2, these parameters are input into a pre-constructed reactive power contribution cost-effectiveness model to calculate the "reactive power contribution cost-effectiveness" of each node. This indicator quantifies the ratio between the actual contribution of a unit reactive power regulation to the voltage increase at the end point and the cost of the node's output fluctuation, accurately identifying those high-efficiency nodes that "can most effectively raise the voltage at the end point with the least reactive power regulation and have minimal fluctuation impact." Step S3 sorts the nodes from high to low based on this cost-effectiveness value and further divides them into a priority zone, an intermediate support zone, and an upstream reserve zone. This zoning strategy establishes a clear "tier" for subsequent regulation, ensuring that "nodes with good performance and low cost are called upon first" when regulation is needed. When the voltage at the end node is detected to be lower than the set threshold in real time, step S4 sequentially calls the reactive power regulation capacity of photovoltaic nodes in each zone according to the order of "priority zone, intermediate support zone, and upstream backup zone". This hierarchical calling mechanism avoids the waste of resources and over-regulation caused by indiscriminate regulation across the entire network, and prioritizes the use of the most cost-effective reactive power resources to quickly respond to voltage drops. If the voltage at the end node still cannot be restored to the normal range after all the reactive power regulation capacity of all photovoltaic nodes has been exhausted, step S5 activates the active power reduction mechanism. At this time, instead of simply including all nodes that can be reduced or sorting them only according to traditional sensitivity, the nodes are sorted according to the "cost-effectiveness of active power contribution". The nodes with the lowest active power reduction cost are prioritized for active power transfer. That is, when it is necessary to reduce active power to support the voltage, the nodes with the "best effect on the end voltage improvement per unit of active power reduction, but the smallest impact on users and power generation loss" are selected for power curtailment. In this way, the total power curtailment is kept to a minimum while ensuring voltage recovery, thus maximizing the user's electricity experience and the power generation revenue of distributed photovoltaics.

[0024] This invention improves the absorption capacity and voltage support capacity of mountain power distribution networks for distributed photovoltaic power generation by optimizing control strategies, and provides an efficient solution that balances grid security and user interests to address the end-point voltage fluctuation problem in the context of high-proportion photovoltaic access in the future.

[0025] Preferably, N distributed photovoltaic power sources connected to the grid sequentially on the line are taken as photovoltaic nodes i. In step S1, the electrical distance is defined as the equivalent electrical distance from photovoltaic node i to the end node. Among them, electrical distance , representing the equivalent impedance of the line between photovoltaic node i and the downstream photovoltaic node i-1. This represents the set of line segments from photovoltaic node i to terminal node 0; The step of obtaining reactive voltage sensitivity in step S1 is as follows: divide the voltage change of the end node by the reactive power change of a single photovoltaic node i. The adjustable reactive power margin in step S1 is: ,in Grid connection limits reactive power cap. , This represents the rated apparent power of the photovoltaic inverter corresponding to the i-th photovoltaic node. This represents the real-time active power output of the i-th photovoltaic node; The definition of topological influence in step S1 is as follows: ,in This represents the number of downstream controllable user nodes of the i-th photovoltaic node, and N is the total number of user nodes under the distribution line; Traditional control strategies prioritize proximity to the target point, such as electrical distance and reactive power voltage sensitivity, but neglect the position and extent of nodes in the overall network structure. Some nodes, although far from the target point, may be located at branch intersections or control multiple downstream paths. Prioritizing nodes with a large control range can improve the overall efficiency of voltage boosting at the end.

[0026] Current dispatching systems mostly judge photovoltaic (PV) participation based on "static capabilities" (such as reactive power margin), neglecting the "output stability" during actual operation. PV nodes with large fluctuations may be effective momentarily, but become unstable the next moment, easily causing secondary voltage dips or control rebounds. Introducing a PV output fluctuation factor is beneficial to improving the stability of the main station's control. The PV output fluctuation factor is the ratio of the standard deviation of the active power output of a PV access node to its mean within a specified time window.

[0027] The preferred reactive power contribution cost-effectiveness model is expressed as follows: ; in These are the coefficients for topological influence, electrical distance, and fluctuation influence factor, respectively. These are the normalized reactive voltage sensitivity, adjustable reactive margin, topological influence, electrical distance, and photovoltaic output fluctuation factor, respectively.

[0028] Preferably, the specific steps of step S4 are as follows: Step S41: Construct the processing set ; Step S42: Store the control partition with the highest reactive power contribution cost-effectiveness in the processing set; Step S43: Calculate the maximum end voltage increase limit within the processing set, and determine whether the maximum end voltage increase limit is greater than the end gap voltage. If it is greater, proceed to step S44; if it is less, proceed to step S42. The formula for obtaining the maximum upper limit of the terminal voltage increase is as follows: ; Step S44: Based on the current processing set Perform total reactive power demand estimation: ; Combine the current processing set The photovoltaic nodes are arranged in descending order of reactive power contribution cost-effectiveness to form an adjustment sequence; Starting from the first node in the sequence, reactive power is allocated sequentially, prioritizing nodes with higher rankings, within the available reactive power margin. The reactive power output must be within the specified range, and the output reactive power cannot exceed the total reactive power demand. And update the end gap voltage after each call. until If the value is less than or equal to 0, stop calling the photovoltaic node.

[0029] In practice, step S4 does not simply involve a one-time call to all nodes. Instead, steps S41 to S44 construct a closed-loop control process that proceeds from best to worst, gradually expands capacity, and precisely allocates resources. First, step S41 initializes a blank processing set. Then, step S42, based on the previously established reactive power contribution cost-effectiveness ranking, stores nodes in the highest priority control zone (i.e., the top 30% of nodes with the highest cost-effectiveness) into this set. This ensures that control resources are first locked onto the group of highly efficient nodes that contribute the most to the voltage increase per unit of reactive power adjustment and have the lowest output fluctuation cost. Next, step S43 introduces a crucial judgment step: using a preset formula to calculate the maximum voltage increase limit for the terminal, it quantitatively assesses the maximum theoretical voltage rise that all photovoltaic nodes in the current processing set can generate after exhausting their available reactive power margin. This value is then compared with the actual terminal voltage gap (i.e., the difference between the target voltage and the current real-time voltage). This assessment mechanism completely changes the passive mode of the traditional method of "blindly calling and observing while adjusting," achieving proactive prediction of "assessing capabilities first, then deciding on actions." If the voltage boost capacity of the current collection is insufficient to fill the gap, step S42 is executed to include the photovoltaic nodes of the next control zone (intermediate support zone) into the collection. This process is repeated until the voltage boost limit of the collection is greater than or equal to the end gap voltage. This step-by-step expansion strategy allows the control system to meet the voltage recovery requirements with the minimum number of participating nodes, avoiding the waste of reactive power resources or excessive disturbance to the upstream power grid caused by calling all nodes at once. Once it is determined that the processing collection has sufficient regulation capacity, step S44 is further refined: First, the total reactive power required to fill the end gap voltage is calculated based on the total demand reactive power estimation formula. Then, the photovoltaic nodes in the collection are arranged again according to the reactive power contribution cost-effectiveness from high to low to form a regulation sequence, and reactive power output is allocated sequentially starting from the first node in the sequence. Each node outputs reactive power within its own available reactive power margin, and the cumulative output is controlled by the total demand reactive power. The end gap voltage is updated in real time after each call, and the call is stopped immediately when the gap voltage is less than or equal to zero. This allocation method of "gradual allocation, dynamic updating, and stopping when the target is reached" ensures that the accuracy of reactive power regulation resources is achieved to the optimal state of "allocation on demand, no more and no less". This not only ensures that the terminal voltage is accurately restored to the normal range, but also reserves adjustment margin for possible voltage fluctuations in the future.

[0030] Preferably, the specific steps of step S5 are as follows: Step S51: Calculate the residual voltage gap after reactive power regulation , ,in For low voltage threshold, The end gap voltage updated for all photovoltaic nodes after step S44; Step S52: In the processing set The photovoltaic nodes with a maximum active power reduction of 0 are removed from the pool to obtain the candidate set; Step S53: Define the active power voltage rise sensitivity as: the voltage change at the end node divided by the active power change per unit of a single photovoltaic node i; The active power voltage rise sensitivity was used instead of the reactive power voltage rise sensitivity to calculate the active power contribution cost-effectiveness of photovoltaic nodes in the candidate pool. ,in , Normalized active power boost sensitivity; Step S54: Sort all photovoltaic nodes in the candidate set from largest to smallest according to their active power contribution cost-effectiveness, forming an active power reduction queuing sequence; Step S55: Calculate the voltage contribution that the j-th photovoltaic node can provide under the maximum allowable reduction in the active power reduction queuing sequence. , , This represents the maximum permissible active power reduction for the j-th photovoltaic node. Step S56: Determine voltage contribution Is it greater than or equal to the residual voltage gap? If it is less than the current maximum allowable active power reduction of the photovoltaic node, then the residual voltage gap is updated. Then, the next photovoltaic node is called to re-execute step S55. If the value is greater than or equal to the active power reduction, the active power reduction amount is obtained based on the active power voltage rise sensitivity of the current photovoltaic node, and the adjustment ends. Obtaining the active power reduction amount based on the active power voltage rise sensitivity of the current photovoltaic node means using the residual voltage gap. The result is obtained by dividing by the active power boost sensitivity of the photovoltaic node.

[0031] To fundamentally address the problem of "excessive total power curtailment and degraded user experience" caused by traditional technologies that simply include all nodes that can be reduced in the reduction scope when reactive power is insufficient, or that only sort by a single sensitivity, step S5 first calculates the residual voltage gap that still exists after the previous reactive power adjustment, i.e., the difference between the actual terminal voltage and the low voltage threshold. This quantified gap provides a precise target value for subsequent active power reduction, avoiding blind reduction. Subsequently, step S52 removes photovoltaic nodes with a maximum active power reduction of 0 from the current processing set, forming a candidate set. This screening operation ensures that the subsequent targets are all nodes that truly have active power regulation capabilities, improving regulation efficiency. Based on this, step S53 introduces the key indicator of "active power voltage rise sensitivity," which is the ratio of the voltage change of the terminal node to the unit amount of active power change of a single photovoltaic node. This is used to quantify the actual improvement effect of a unit active power reduction on the terminal voltage, and uses this indicator to replace the traditional reactive power voltage rise sensitivity. Combined with normalization processing, the "active power contribution cost-effectiveness" of each node is calculated. This indicator is designed with high precision—it no longer simply focuses on "which node's active power reduction is most sensitive to voltage increase," but comprehensively measures the ratio between "the voltage increase contribution brought by a unit of active power reduction" and "the cost of the node's output fluctuation," making a high-performance node mean "achieving the greatest voltage recovery effect with the least active power sacrifice." Step S54 then sorts the candidate set from high to low based on this cost-effectiveness, forming an active power reduction queue. This sorting logic ensures that nodes with "low cost and good effect" are prioritized when regulation is initiated, controlling the expansion of total power rationing at the source. Steps S55 and S56 constitute a closed-loop precise allocation process: the system sequentially traverses the nodes in the queue, first calculating the theoretical contribution value that the current node can provide to the terminal voltage under the maximum allowable active power reduction, and comparing it with the current residual voltage gap. If the maximum contribution of a node is still less than the gap, it means that the full adjustable capacity of the node needs to be used. The system will then call its maximum allowable active power reduction, update the residual voltage gap, and continue to call the next node. Once a node's voltage contribution is greater than or equal to the residual gap, the system will accurately back-calculate the active power reduction required to just make up for the gap based on the active power voltage lifting sensitivity of the node, and end the entire adjustment process immediately after the call.

[0032] A photovoltaic control system based on contribution-performance ratio, using the aforementioned photovoltaic control method based on contribution-performance ratio, includes: The parameter acquisition module is used to acquire the operating parameters of multiple grid-connected photovoltaic nodes on the distribution line. The operating parameters include electrical distance, reactive voltage sensitivity, adjustable reactive power margin, topological influence, and photovoltaic output fluctuation factor. The cost-effectiveness calculation module is used to input the operating parameters into the reactive power contribution cost-effectiveness model to obtain the reactive power contribution cost-effectiveness of each photovoltaic node. The partitioning and sorting module is used to sort photovoltaic nodes from high to low according to their reactive power contribution cost-effectiveness and divide the photovoltaic nodes into multiple control partitions. The reactive power regulation module is used to monitor the voltage of the end node in real time. When the end voltage is lower than the set threshold, the reactive power regulation capacity of the photovoltaic node is called in sequence according to the partition order until the end voltage returns to the normal range. The active power regulation module is used to prioritize the node with the lowest active power reduction cost for active power transfer when the reactive power regulation capacity of all photovoltaic nodes is insufficient to restore the end voltage, based on the cost-effectiveness of active power contribution, in order to minimize the total power curtailment.

[0033] Preferably, in the parameter acquisition module, N distributed photovoltaic power sources connected to the grid in sequence on the line are taken as photovoltaic node i; The electrical distance is the equivalent electrical distance from photovoltaic node i to the end node; the reactive voltage sensitivity is the ratio of the voltage change at the end node to the reactive power change per unit amount at a single photovoltaic node i. The adjustable reactive power margin is determined based on the rated apparent power of the photovoltaic inverter and the real-time active power output of the photovoltaic node. The topological influence is determined based on the ratio of the number of downstream controllable user nodes of photovoltaic node i to the total number of user nodes under the distribution line. The photovoltaic power output fluctuation factor is the ratio of the standard deviation to the mean of the active power output of the photovoltaic access node within a specified time window.

[0034] Preferably, the cost-effectiveness calculation module is equipped with a reactive power contribution cost-effectiveness model. This model combines the coefficients of topological influence, electrical distance, and fluctuation influence factor, as well as the normalized reactive voltage sensitivity, adjustable reactive power margin, topological influence, electrical distance, and photovoltaic power output fluctuation factor to calculate the reactive power contribution cost-effectiveness.

[0035] Preferably, the reactive power control module specifically performs the following: Construct a processing set and store the control partition with the highest reactive power contribution cost-effectiveness into the processing set; Calculate the maximum upper limit of the terminal voltage increase within the processing set, and determine whether the upper limit is greater than the terminal gap voltage. If it is not satisfied, continue to add the next control zone to the processing set. If the conditions are met, the total reactive power demand of the current processing set is estimated. The photovoltaic nodes in the processing set are arranged in descending order of reactive power contribution cost-effectiveness to form an adjustment sequence. Reactive power output is allocated sequentially starting from the first node in the sequence. Reactive power is output within the available reactive power margin and does not exceed the total reactive power demand. The end gap voltage is updated after each call until the end gap voltage is less than or equal to 0 and the call is stopped.

[0036] Preferably, the active power control module specifically performs the following: Calculate the residual voltage gap after reactive power regulation; remove photovoltaic nodes with a maximum active power reduction of 0 from the processing set to obtain the candidate set; The ratio of the voltage change at the end node to the unit change in active power of a single photovoltaic node i is used as the active power voltage rise sensitivity. The active power contribution cost-effectiveness of photovoltaic nodes in the candidate pool is calculated using the active power voltage rise sensitivity. The photovoltaic nodes in the candidate set are sorted from largest to smallest according to their active power contribution cost-effectiveness to form an active power reduction queuing sequence. Calculate the voltage contribution that each photovoltaic node can provide under the maximum allowable active power reduction in turn. If the voltage contribution is less than the residual voltage gap, call the maximum allowable active power reduction of the current node and update the residual voltage gap, and continue to call the next node. If the residual voltage gap requirement is met, the active power reduction amount is determined based on the current node's active power voltage rise sensitivity, and the voltage adjustment is completed.

[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A photovoltaic regulation method based on contributional cost-effectiveness, characterized in that, Includes the following steps: S1: Obtain the operating parameters of multiple grid-connected photovoltaic nodes on the distribution line. The operating parameters include electrical distance, reactive voltage sensitivity, adjustable reactive margin, topological influence, and photovoltaic output fluctuation factor. S2: Input the operating parameters into the reactive power contribution cost-effectiveness model to obtain the reactive power contribution cost-effectiveness; S3: Sort the photovoltaic nodes from high to low according to their reactive power contribution cost-effectiveness and divide them into multiple control zones; S4: Monitor the voltage of the end node in real time. When the end voltage is lower than the set threshold, call up the reactive power regulation capacity of the photovoltaic nodes in the order of partitions until the end voltage is restored to the normal range. If the reactive power regulation capacity of all photovoltaic nodes is insufficient to restore the end voltage, then execute step S5. Step S5: Based on the cost-effectiveness of active power contribution, prioritize calling the node with the lowest active power reduction cost for active power transfer in order to minimize the total power curtailment.

2. The photovoltaic regulating method based on contributional cost-effectiveness according to claim 1, characterized in that, Taking N distributed photovoltaic power generation grid-connected points sequentially connected to the line as photovoltaic nodes i, the electrical distance in step S1 is defined as: the equivalent electrical distance from photovoltaic node i to the end node. Among them, electrical distance , representing the equivalent impedance of the line between photovoltaic node i and the downstream photovoltaic node i-1. This represents the set of line segments from photovoltaic node i to terminal node 0; The step of obtaining reactive voltage sensitivity in step S1 is as follows: divide the voltage change of the end node by the reactive power change of a single photovoltaic node i. The adjustable reactive power margin in step S1 is: ,in Grid connection limits reactive power cap. , This represents the rated apparent power of the photovoltaic inverter corresponding to the i-th photovoltaic node. This represents the real-time active power output of the i-th photovoltaic node; The definition of topological influence in step S1 is as follows: ,in This represents the number of downstream controllable user nodes of the i-th photovoltaic node, and N is the total number of user nodes under the distribution line.

3. The photovoltaic control method based on contribution-performance ratio according to claim 1, characterized in that, The reactive power contribution cost-effectiveness model is expressed as follows: ； in These are the coefficients for topological influence, electrical distance, and fluctuation influence factor, respectively. These are the normalized reactive voltage sensitivity, adjustable reactive margin, topological influence, electrical distance, and photovoltaic output fluctuation factor, respectively.

4. The photovoltaic regulating method based on contributional cost-effectiveness according to claim 1, characterized in that, The specific steps of step S4 are as follows: Step S41: Constructing a processing portfolio ; Step S42: Store the control partition with the highest reactive power contribution cost-effectiveness in the processing set; Step S43: Calculate the maximum end voltage increase limit within the processing set, and determine whether the maximum end voltage increase limit is greater than the end gap voltage. If it is greater, proceed to step S44; if it is less, proceed to step S42. The formula for obtaining the maximum upper limit of the terminal voltage increase is as follows: ； Step S44: Based on the current processing portfolio Total demand reactive power estimation is performed: ; The current processing set The photovoltaic nodes are arranged in descending order according to the cost performance of reactive contribution to form an adjustment sequence. Starting from the first node in the sequence, reactive power is allocated sequentially, prioritizing nodes with higher rankings, within the available reactive power margin. The reactive power output must be within the specified range, and the output reactive power cannot exceed the total reactive power demand. And update the end gap voltage after each call. until If the value is less than or equal to 0, stop calling the photovoltaic node.

5. A photovoltaic control method based on contribution-performance ratio according to claim 4, characterized in that, The specific steps of step S5 are as follows: Step S51: Calculate the residual voltage gap after reactive power regulation , ,in For low voltage threshold, The end gap voltage updated for all photovoltaic nodes after step S44; Step S52: In the processing set , the photovoltaic node with the maximum active reduction amount of 0 is removed to obtain a candidate set; Step S53: Define the active power voltage rise sensitivity as: the voltage change at the end node divided by the active power change per unit of a single photovoltaic node i; The active power voltage rise sensitivity was used instead of the reactive power voltage rise sensitivity to calculate the active power contribution cost-effectiveness of photovoltaic nodes in the candidate pool. ,in , Normalized active power boost sensitivity; Step S54: Sort all photovoltaic nodes in the candidate set from largest to smallest according to their active power contribution cost-effectiveness, forming an active power reduction queuing sequence; Step S55: Calculate the voltage contribution that the j-th photovoltaic node can provide under the maximum allowable reduction in the active power reduction queuing sequence. , , This represents the maximum permissible active power reduction for the j-th photovoltaic node. Step S56: Determine voltage contribution Is it greater than or equal to the residual voltage gap? If it is less than the current maximum allowable active power reduction of the photovoltaic node, then the residual voltage gap is updated. Then, call the next photovoltaic node to re-execute step S55. If it is greater than or equal to the active power reduction, obtain the active power reduction amount based on the active power voltage rise sensitivity of the current photovoltaic node, and end the adjustment.

6. A contribution-based cost-effective photovoltaic regulation system, comprising: The photovoltaic control method based on contribution-performance ratio as described in any one of claims 1 to 5 includes: The parameter acquisition module is used to acquire the operating parameters of multiple grid-connected photovoltaic nodes on the distribution line. The operating parameters include electrical distance, reactive voltage sensitivity, adjustable reactive power margin, topological influence, and photovoltaic output fluctuation factor. The cost-effectiveness calculation module is used to input the operating parameters into the reactive power contribution cost-effectiveness model to obtain the reactive power contribution cost-effectiveness of each photovoltaic node. The partitioning and sorting module is used to sort photovoltaic nodes from high to low according to their reactive power contribution cost-effectiveness and divide the photovoltaic nodes into multiple control partitions. The reactive power regulation module is used to monitor the voltage of the end node in real time. When the end voltage is lower than the set threshold, the reactive power regulation capacity of the photovoltaic node is called in sequence according to the partition order until the end voltage returns to the normal range. The active power regulation module is used to prioritize the node with the lowest active power reduction cost for active power transfer when the reactive power regulation capacity of all photovoltaic nodes is insufficient to restore the end voltage, based on the cost-effectiveness of active power contribution, in order to minimize the total power curtailment.

7. A photovoltaic control system based on contribution-performance ratio according to claim 6, characterized in that, In the parameter acquisition module, N distributed photovoltaic power sources connected to the grid in sequence on the line are taken as photovoltaic node i; The electrical distance is the equivalent electrical distance from photovoltaic node i to the end node; the reactive voltage sensitivity is the ratio of the voltage change at the end node to the reactive power change per unit amount at a single photovoltaic node i. The adjustable reactive power margin is determined based on the rated apparent power of the photovoltaic inverter and the real-time active power output of the photovoltaic node. The topological influence is determined based on the ratio of the number of downstream controllable user nodes of photovoltaic node i to the total number of user nodes under the distribution line. The photovoltaic power output fluctuation factor is the ratio of the standard deviation to the mean of the active power output of the photovoltaic access node within a specified time window.

8. The contributionally cost-based photovoltaic regulating system according to claim 6, wherein, The cost-effectiveness calculation module is equipped with a reactive power contribution cost-effectiveness model. This model combines the coefficients of topological influence, electrical distance, and fluctuation influence factor, as well as the normalized reactive voltage sensitivity, adjustable reactive power margin, topological influence, electrical distance, and photovoltaic output fluctuation factor to calculate the reactive power contribution cost-effectiveness.

9. The contributionally cost-based photovoltaic regulating system according to claim 6, wherein, The reactive power control module specifically performs the following: Construct a processing set and store the control partition with the highest reactive power contribution cost-effectiveness into the processing set; Calculate the maximum upper limit of the terminal voltage increase within the processing set, and determine whether the upper limit is greater than the terminal gap voltage. If it is not satisfied, continue to add the next control zone to the processing set. If the conditions are met, the total reactive power demand of the current processing set is estimated. The photovoltaic nodes in the processing set are arranged in descending order of reactive power contribution cost-effectiveness to form an adjustment sequence. Reactive power output is allocated sequentially starting from the first node in the sequence. Reactive power is output within the available reactive power margin and does not exceed the total reactive power demand. The end gap voltage is updated after each call until the end gap voltage is less than or equal to 0 and the call is stopped.

10. The contributionally cost-based photovoltaic regulating system according to claim 6, wherein, The active power control module specifically performs the following: Calculate the residual voltage gap after reactive power regulation; remove photovoltaic nodes with a maximum active power reduction of 0 from the processing set to obtain the candidate set; The ratio of the voltage change at the end node to the unit change in active power of a single photovoltaic node i is used as the active power voltage rise sensitivity. The active power contribution cost-effectiveness of photovoltaic nodes in the candidate pool is calculated using the active power voltage rise sensitivity. The photovoltaic nodes in the candidate set are sorted from largest to smallest according to their active power contribution cost-effectiveness to form an active power reduction queuing sequence. Calculate the voltage contribution that each photovoltaic node can provide under the maximum allowable active power reduction in turn. If the voltage contribution is less than the residual voltage gap, call the maximum allowable active power reduction of the current node and update the residual voltage gap, and continue to call the next node. If the residual voltage gap requirement is met, the active power reduction amount is determined based on the current node's active power voltage rise sensitivity, and the voltage adjustment is completed.

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