A method for assessing the capacity of distributed photovoltaic grid connection

Abstract

This invention discloses a method for evaluating the capacity of distributed photovoltaic (PV) grid connection. The method includes: first, obtaining the preset grid connection capacity of distributed PV in a preset area at at least one node, and the resistance and reactance values ​​of every two adjacent nodes in the preset area; and second, obtaining the minimum active power, minimum reactive power, and maximum voltage of each node in the preset area at time t. Then, through iterative calculation, the target grid connection voltage is determined. Finally, the target grid connection voltage of all nodes at all times is compared with the preset power supply voltage range to obtain the grid connection evaluation result. This method not only considers the complex network topology and electrical parameters within the distribution area but also incorporates the actual power load characteristics at different times. It can more accurately determine the upper limit of the PV capacity suitable for grid connection at each node within the distribution area, effectively preventing voltage exceedance issues caused by PV grid connection, thereby ensuring the safe and reliable operation of the power grid in the distribution area.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a method for assessing the capacity of distributed photovoltaic power grid connection. Background Technology

[0002] Against the backdrop of China's commitment to promoting the development of high-quality distribution networks, distributed photovoltaic (PV) power generation systems, as a key component in driving clean energy applications, are seeing their deployment scale continuously expand in low-voltage distribution networks (transformer areas). With advancements in low-voltage transformer area data acquisition technology, including the increasing frequency of data collection such as voltage, current, and power, and the continuous improvement of low-voltage grid maps, these advancements should provide a more solid foundation for assessing the adjustability of transformer areas.

[0003] However, traditional methods for assessing the capacity of distributed photovoltaic (PV) grid connections mainly rely on historical data of user electricity load and the rated capacity of transformers in the distribution area for simple estimation. While this method can ensure the safe and stable operation of the distribution area to a certain extent, it has obvious limitations.

[0004] Specifically, traditional methods for assessing distributed photovoltaic (PV) grid connection capacity fail to adequately consider the influence of various complex factors within the distribution area. This means that even if PV capacity is connected within the theoretically calculated safe range, unforeseen power flow changes may trigger power quality issues such as overvoltage, threatening the overall stable operation of the distribution area's power grid. This limitation highlights the inadequacy of current technologies in assessing distributed PV grid connection capacity. Summary of the Invention

[0005] Based on this, it is necessary to propose a distributed photovoltaic (PV) grid connection capacity assessment method to address the above-mentioned problems. This method not only considers the complex network topology and line electrical parameters within the distribution area, but also incorporates the actual power load characteristics at different times. This method can more accurately determine the upper limit of the PV capacity suitable for connection at each node within the distribution area, effectively preventing voltage over-limit problems caused by PV grid connection, thereby ensuring the safe and reliable operation of the power grid in the distribution area.

[0006] To achieve the above objectives, the present invention provides a method for assessing the capacity of distributed photovoltaic (PV) grid connection in a first aspect, the method comprising:

[0007] The system obtains the preset access capacity of distributed photovoltaic power at at least one node in the preset area, the resistance and reactance values ​​of every two adjacent nodes in the preset area, and the minimum active power, minimum reactive power and maximum voltage of each node in the preset area at time t, where t is a positive integer and the initial value of t is 1.

[0008] Based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power and maximum voltage of all nodes at time t, the access voltage of each node at time t is determined, and the access voltage is taken as the first access voltage at time t.

[0009] The k+1th access voltage of each node at time t is determined based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node, where k is a positive integer and the initial value of k is 1.

[0010] When the absolute value of the difference between the kth access voltage and the (k+1th access voltage) of each node at time t satisfies the preset iteration condition, the (k+1th access voltage) is taken as the target access voltage at time t. Let t = t+1, and return to the step of obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset region at time t, until t equals the total number of time points.

[0011] If the absolute value of the difference between the kth access voltage and the (k+1th access voltage) of at least one node at time t does not satisfy the preset iteration condition, let k = k+1, and return to the step of determining the (k+1th access voltage) of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node.

[0012] The access evaluation results are determined based on the target access voltage and preset power supply voltage range of all nodes at all times.

[0013] Optionally, determining the access voltage of each node at time t based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power, and maximum voltage of all nodes at time t includes:

[0014] Using formula Determine the access voltage of each node at time t;

[0015] Among them, R U,m,t R is the access voltage of the m-th node at time t. U,0 The voltage at the beginning of the preset region is M, where M is the total number of nodes and R is R. P,min,y,t Let R be the minimum nodal active power of the y-th node at time t. P,pv,y Let R be the preset access capacity of the y-th node. If the y-th node has no preset access capacity, then R... P,pv,y=0, R y R is the resistance value between the y-th node and the (y-1)-th node. Q,min,y,t Let X be the minimum nodal reactive power of the y-th node at time t. y R is the reactance between the y-th node and the (y-1)-th node. U,max,x-1,t Let R be the maximum node voltage of the (x-1)th node at time t. If x = 1, then R U,max,x-1,t =R U,0 .

[0016] Optionally, determining the (k+1)th access voltage of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node includes:

[0017] Using formula Determine the (k+1)th connected voltage of each node at time t;

[0018] in, Let Y be the voltage connected to the m-th node at time t (k+1). mm Let R be the self-admittance between the m-th node and the m-th node. P,min,m,t R is the minimum nodal active power of the m-th node at time t. P,pv,m R represents the preset access capacity for the m-th node. If the m-th node does not have a preset access capacity, then R... P,pv,m =0, j is the imaginary unit of the complex number, R Q,min,m,t Let be the minimum nodal reactive power of the m-th node at time t. Let Y be the conjugate of the k-th access voltage of the m-th node at time t, where M is the total number of nodes. If m = x, then Y... mx Let Y be the self-admittance between the m-th node and the x-th node. If m ≠ x, then Y mx Let be the mutual admittance between the m-th node and the x-th node. Let k be the voltage connected to the x-th node at time t.

[0019] Optionally, the preset iteration condition is that the absolute value of the difference between the k-th access voltage and the (k+1)-th access voltage of each node at time t is less than the iteration voltage difference threshold.

[0020] Optionally, determining the access evaluation result based on the target access voltage and preset power supply voltage range of all nodes at all times includes:

[0021] If the target access voltage of each node at each time is within the preset power supply voltage range, then the access evaluation result is that the preset access capacity of the distributed photovoltaic system at at least one node meets the access requirements of the preset area; otherwise, the access evaluation result is that the preset access capacity of the distributed photovoltaic system at at least one node does not meet the access requirements of the preset area.

[0022] Optionally, obtaining the minimum node active power, minimum node reactive power, and maximum node voltage of each node in the preset region at time t includes:

[0023] Obtain the active power, reactive power, and voltage of each node in the preset area at time t each day;

[0024] The minimum node active power at time t is determined based on the node active power of each node at time t across all days.

[0025] The minimum node reactive power at time t is determined based on the node reactive power of each node at time t across all days.

[0026] The maximum node voltage at time t is determined based on the node voltage of each node at time t across all days.

[0027] Optionally, obtaining the node active power, node reactive power, and node voltage of each node in the preset area at time t each day includes:

[0028] Obtain the historical active power, historical reactive power, and historical voltage of each user in the preset area at time t each day, as well as the topology diagram of the preset area;

[0029] For each user, the historical active power, historical reactive power, and historical voltage at time t of each day are cleaned to obtain the standard active power, standard reactive power, and standard voltage for each user at time t of each day.

[0030] The user nodes are merged according to the topology diagram to obtain multiple nodes;

[0031] The node active power, node reactive power, and node voltage at time t of each day are determined based on the standard active power, standard reactive power, and standard voltage of all users corresponding to each node at time t of each day.

[0032] Optionally, determining the node active power, node reactive power, and node voltage at time t of each day based on the standard active power, standard reactive power, and standard voltage of all users corresponding to each node at time t of each day includes:

[0033] Using formula Determine the active power and reactive power of each node at time t each day;

[0034] Using formula Determine the node voltage of each node at time t each day;

[0035] Where, if r = P, then R r,m,n,t Let R be the node active power of the m-th node at time t on day n. r ′ ,i,n,t Let R be the standard active power of the i-th user at time t on day n. If r = Q, then R r,m,n,t Let R be the node reactive power of the m-th node at time t on day n. r ′ ,i,n,t Let I be the standard reactive power of the i-th user at time t on day n. m R represents the total number of users at the m-th node. U,m,n,t Let R′ be the node voltage of the m-th node at time t on day n. U,i,n,t Let be the standard voltage for the i-th user at time t on day n.

[0036] Optionally, the step of cleaning the historical active power, historical reactive power, and historical voltage for each user at time t each day to obtain the standard active power, standard reactive power, and standard voltage for each user at time t each day includes:

[0037] The average active power, average reactive power, and average voltage of each user at time t are determined based on the historical active power, historical reactive power, and historical voltage of each user at time t on all days.

[0038] The variances of active power, reactive power, and voltage for each user at time t are determined based on the average active power, average reactive power, and average voltage for each user at time t across all days, as well as the historical active power, historical reactive power, and historical voltage for each user at time t.

[0039] For each user's historical active power, historical reactive power, and historical voltage at time t on each day, if the absolute value of the difference between the historical active power of user i at time t on day n and the average active power at that time is greater than a preset multiple of the variance of active power at that time, then the historical active power of user i at time t on day n is determined to be an outlier, and the historical active power of user i at time t on day n is corrected to the average active power of user i at time t. If the absolute value of the difference between the historical reactive power of user i at time t on day n and the average reactive power at that time is greater than a preset multiple of the variance of reactive power at that time... If the historical reactive power of user i at time t on day n is determined to be an outlier, the reactive power of user i at time t on day n is corrected to the average reactive power of user i at time t. If the absolute value of the difference between the historical voltage of user i at time t on day n and the average voltage at the corresponding time is greater than a preset multiple of the voltage variance at the corresponding time, the historical voltage of user i at time t on day n is determined to be an outlier, and the voltage of user i at time t on day n is corrected to the average voltage of user i at time t, so as to obtain the standard active power, standard reactive power and standard voltage of each user at time t on each day.

[0040] Optionally, determining the average active power, average reactive power, and average voltage of each user at time t based on the historical active power, historical reactive power, and historical voltage of each user at time t across all days includes:

[0041] Using formula Determine the average active power, average reactive power, and average voltage for each user at time t.

[0042] The determination of the active power variance, reactive power variance, and voltage variance for each user at time t, based on the average active power, average reactive power, and average voltage of each user at time t across all days, includes:

[0043] Using formula Determine the active power variance, reactive power variance, and voltage variance for each user at time t.

[0044] Where, if r = P, then Let R be the average active power of the i-th user at time t. r,i,n,t Let δ be the historical active power of the i-th user at time t on day n. r,i,t Let r = Q, then... Let R be the average reactive power of the i-th user at time t. r,i,n,t Let δ be the historical reactive power of the i-th user at time t on day n. r,i,t Let r = U, then... Let R be the average voltage of the i-th user at time t. r,i,n,t Let δ be the historical voltage of the i-th user at time t on day n. r,i,t Let N be the voltage variance of the i-th user at time t, and N be the total number of days.

[0045] To achieve the above objectives, the present invention provides a distributed photovoltaic (PV) grid connection capacity assessment device in a second aspect, the device comprising:

[0046] The acquisition module is used to acquire the preset access capacity of distributed photovoltaic power in at least one node in the preset area, the resistance value and reactance value of each two adjacent nodes in the preset area, and the minimum active power, minimum reactive power and maximum voltage of each node in the preset area at time t, where t is a positive integer and the initial value of t is 1.

[0047] The initial determination module is used to determine the access voltage of each node at time t based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power and maximum voltage of all nodes at time t, and to use the access voltage as the first access voltage at time t.

[0048] The iterative determination module is used to determine the (k+1)th access voltage of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node, where k is a positive integer and the initial value of k is 1.

[0049] The time iteration module is used to take the k+1 access voltage as the target access voltage at time t when the absolute value of the difference between the kth access voltage and the (k+1)th access voltage of each node at time t satisfies the preset iteration condition, and then return to the step of obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset region at time t, until t equals the total number of time points.

[0050] The voltage iteration module is used to, when there is at least one node at time t whose absolute value of the difference between the kth access voltage and the (k+1th access voltage) does not satisfy the preset iteration condition, let k = k+1, and return to execute the step of determining the (k+1th access voltage) of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node.

[0051] The access assessment module is used to determine the access assessment results based on the target access voltage and preset power supply voltage range of all nodes at all times.

[0052] To achieve the above objectives, the present invention provides, in a third aspect, a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the method as described in any one of the first aspects.

[0053] To achieve the above objectives, the present invention provides a computer device in a fourth aspect, including a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the method as described in any one of the first aspects.

[0054] The present invention provides the following advantages: The method obtains the preset access capacity of distributed photovoltaic power at at least one node in a preset region, the resistance and reactance values ​​of every two adjacent nodes in the preset region, and the minimum active power, minimum reactive power, and maximum voltage of each node in the preset region at time t (where t is a positive integer and its initial value is 1). Then, based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power, and maximum voltage of all nodes at time t, the method determines the value of each node. The system calculates the access voltage at time t and uses this voltage as the first access voltage at time t. Then, based on the k-th access voltage, minimum active power, minimum reactive power, and the preset access capacity of at least one node at time t, it determines the (k+1)-th access voltage at time t for each node, where k is a positive integer and its initial value is 1. Next, when the absolute value of the difference between the k-th and (k+1)-th access voltages at time t for each node satisfies the preset iteration condition, the (k+1)-th access voltage is taken as the target access voltage at time t. Let t = t+1, and return to the execution state to obtain the target voltage. The method involves determining the minimum active power, minimum reactive power, and maximum voltage of each node in a predefined area at time t, and repeating this process until t equals the total number of times. If the absolute value of the difference between the k-th access voltage and the (k+1)-th access voltage of at least one node at time t does not meet the predefined iteration condition, then k = k+1. The method then returns to the step of determining the (k+1)-th access voltage of each node at time t based on the k-th access voltage, minimum active power, minimum reactive power, and the predefined access capacity of at least one node. Finally, the access evaluation result is determined based on the target access voltage and the predefined supply voltage range of all nodes at all times. This method not only considers the complex network topology and line electrical parameters within the distribution area but also incorporates the actual power load characteristics at different times and performs detailed analysis. This allows for a more accurate determination of the upper limit of photovoltaic capacity suitable for each node within the distribution area, providing a scientific basis for the optimized configuration of distributed photovoltaic systems. It effectively prevents voltage over-limit problems caused by photovoltaic access, thereby ensuring the safe and reliable operation of the distribution area's power grid. This method not only significantly improves the prediction accuracy of the impact of distributed photovoltaic access but also provides strong technical support for promoting the development of high-quality distribution networks in China. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] in:

[0057] Figure 1 This is a schematic diagram of a distributed photovoltaic grid connection capacity assessment method according to an embodiment of this application;

[0058] Figure 2 This is a simplified schematic diagram of the transformer substation network in the embodiments of this application;

[0059] Figure 3 This is a schematic diagram of a distributed photovoltaic access capacity assessment device in an embodiment of this application;

[0060] Figure 4 This is a diagram showing the internal structure of a computer device in some embodiments. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] Against the backdrop of China's commitment to promoting the development of high-quality distribution networks, distributed photovoltaic (PV) power generation systems, as a key component in driving clean energy applications, are seeing their deployment scale continuously expand in low-voltage distribution networks (transformer areas). With advancements in low-voltage transformer area data acquisition technology, including the increasing frequency of data collection such as voltage, current, and power, and the continuous improvement of low-voltage grid maps, these advancements should provide a more solid foundation for assessing the adjustability of transformer areas.

[0063] However, traditional methods for assessing the capacity of distributed photovoltaic (PV) grid connections mainly rely on historical data of user electricity load and the rated capacity of transformers in the distribution area for simple estimation. While this method can ensure the safe and stable operation of the distribution area to a certain extent, it has obvious limitations.

[0064] Specifically, traditional methods for assessing distributed photovoltaic (PV) grid connection capacity fail to adequately consider the influence of various complex factors within the distribution area. This means that even if PV capacity is connected within the theoretically calculated safe range, unforeseen power flow changes may trigger power quality issues such as overvoltage, threatening the overall stable operation of the distribution area's power grid. This limitation highlights the inadequacy of current technologies in assessing distributed PV grid connection capacity.

[0065] To address the aforementioned issues, this application proposes a distributed photovoltaic (PV) grid connection capacity assessment method. This method not only considers the complex network topology and line electrical parameters within the distribution area but also incorporates the actual power load characteristics at different times. This allows for a more accurate determination of the upper limit of PV capacity suitable for each node within the distribution area, effectively preventing voltage over-limit issues caused by PV grid connection and ensuring the safe and reliable operation of the power grid in the distribution area. The specific implementation principle will be described in detail in the following embodiments.

[0066] This application provides a method for assessing the capacity of distributed photovoltaic grid connection in its first aspect.

[0067] Please see Figure 1 This is a schematic diagram of a distributed photovoltaic grid connection capacity assessment method according to an embodiment of this application. The method includes:

[0068] Step 110: Obtain the preset access capacity of distributed photovoltaic power at at least one node in the preset area, the resistance and reactance values ​​of every two adjacent nodes in the preset area, and obtain the minimum active power, minimum reactive power and maximum voltage of each node in the preset area at time t, where t is a positive integer and the initial value of t is 1.

[0069] The preset area and preset access capacity can both be determined and set by the operator according to actual needs.

[0070] In some embodiments, the preset area may be a station area.

[0071] Regarding the node partitioning method, in some embodiments, the network topology of a preset area can be obtained, and nodes can be partitioned according to the network topology.

[0072] Furthermore, after dividing the nodes, the historical data collected in the preset area can be analyzed for each node to determine the minimum active power, minimum reactive power and maximum voltage of each node at each time, as well as the resistance and reactance values ​​of each two adjacent nodes for the electrical parameters of the previously constructed lines in the preset area, and the preset access capacity of at least one node can be set.

[0073] Step 120: Based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power and maximum voltage of all nodes at time t, determine the access voltage of each node at time t, and use the access voltage as the first access voltage at time t.

[0074] It should be noted that after distributed photovoltaic (PV) systems are connected to a preset area, they will affect the voltage of that area. That is, after a preset capacity of distributed PV is connected to a node in the preset area, it will not only affect the connection voltage of that node, but also the connection voltage of other nodes in the preset area. Furthermore, the connection voltage of a node will also be affected by resistance, reactance, active power, reactive power, and voltage. Therefore, the connection voltage can be determined based on the preset connection capacity, resistance value, reactance value, minimum active power, minimum reactive power, and maximum voltage.

[0075] It should be further explained that since the access voltage of each node in the preset area will affect each other, in order to avoid overvoltage in the access voltage of each node in the preset area, the minimum active power, minimum reactive power and maximum voltage of the node are used to determine the access voltage. This ensures that the determined access voltage is the maximum, so that the access voltage of each node in the preset area can avoid overvoltage.

[0076] It is understandable that the smaller the node active power, node reactive power, and node voltage of the load, the larger its connected voltage; and when the node active power, node reactive power, and node voltage of the load are at their minimum, its connected voltage reaches its maximum.

[0077] Step 130: Determine the (k+1)th access voltage of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node. k is a positive integer and the initial value of k is 1.

[0078] In some embodiments, the transformer nodes of a preset area can be used as balancing nodes to generate node voltage equations for all nodes. The node voltage equations are then used to determine the (k+1)th access voltage based on the kth access voltage, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity.

[0079] Step 140: When the absolute value of the difference between the kth access voltage and the (k+1th access voltage) of each node at time t satisfies the preset iteration condition, take the (k+1th access voltage) as the target access voltage at time t, let t = t+1, and return to execute the steps of obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset region at time t, until t equals the total number of time points.

[0080] Among them, the preset iteration conditions can be obtained and set by the operator based on a large amount of experience, experiments or statistics.

[0081] In some embodiments, the preset iteration conditions can be the iteration conditions of existing iteration algorithms; for example, the iteration conditions can be satisfied when the threshold is less than or equal to the threshold but not satisfied when the threshold is greater than the threshold, or satisfied when the threshold is less than the threshold but not satisfied when the threshold is greater than or equal to the threshold, etc., which will not be elaborated here.

[0082] It should be noted that when the absolute value of the difference between the kth access voltage and the (k+1th access voltage) of each node at time t satisfies the preset iteration condition, the (k+1th access voltage) is taken as the target access voltage at time t. Let t = t+1, and start iterating again from step 110 in the above embodiment, which is "obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at time t", until t equals the total number of time points.

[0083] Step 150: If the absolute value of the difference between the kth access voltage and the (k+1th access voltage) of at least one node at time t does not satisfy the preset iteration condition, let k = k+1, and return to the step of determining the (k+1th access voltage) of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node.

[0084] It should be noted that if the absolute value of the difference between the k-th access voltage and the (k+1)-th access voltage of at least one node at time t does not meet the preset iteration condition, let k = k+1, and return to step 130 in the above embodiment to re-iterate until the absolute value of the difference between the k-th access voltage and the (k+1)-th access voltage of each node at time t meets the preset iteration condition.

[0085] Step 160: Determine the access evaluation results based on the target access voltage and preset power supply voltage range of all nodes at all times.

[0086] The preset power supply voltage range can be set by the operator based on extensive experience, experiments, or statistics.

[0087] In some embodiments, the preset power supply voltage range can be determined according to the power supply voltage standards formulated by the State Power Supply Bureau.

[0088] In some embodiments, the access evaluation result can be determined based on the comparison between the target access voltage of all nodes at all times and the preset supply voltage range; wherein, the access evaluation result can be either satisfying access or not satisfying access.

[0089] In this embodiment, the method first obtains the preset access capacity of distributed photovoltaic (PV) systems at at least one node in a preset area, as well as the resistance and reactance values ​​of every two adjacent nodes in the preset area. It also obtains the minimum active power, minimum reactive power, and maximum voltage of each node in the preset area at time t. Then, through iterative calculation, the target access voltage is determined. Finally, the target access voltage of all nodes at all times is compared with the preset supply voltage range to obtain the access evaluation result. This method not only considers the complex network topology and line electrical parameters within the distribution area but also incorporates the actual power load characteristics at different times and performs detailed analysis. This allows for a more accurate determination of the upper limit of PV capacity suitable for access at each node within the distribution area, providing a scientific basis for the optimized configuration of distributed PV systems. It effectively prevents voltage exceedance issues caused by PV access, thereby ensuring the safe and reliable operation of the distribution area's power grid. This method not only significantly improves the prediction accuracy of the impact of distributed PV access but also provides strong technical support for promoting the development of high-quality distribution networks in China.

[0090] Furthermore, the approach proposed in this application also has the following advantages: By incorporating the actual electricity load characteristics at different times, with particular attention to the directionality of power flow, it ensures that distributed photovoltaic power is consumed locally as much as possible, avoiding the impact of reverse power flow from distributed photovoltaic on the power grid; by accurately assessing the upper limit of photovoltaic access capacity at each node, grid planners can more flexibly design the layout and scale of distributed photovoltaic to adapt to changes in electricity demand in different regions and time periods, which helps optimize the grid structure, improve the grid's ability to absorb and dispatch renewable energy, and thus enhance the overall flexibility and resilience of the grid; accurate access capacity assessment helps eliminate the concerns of grid operators and distributed photovoltaic investors about power quality issues such as voltage exceeding limits, thereby encouraging more clean energy projects to be implemented, which will accelerate the popularization and application of clean energy, promote the green transformation of the energy structure, and contribute to achieving the "dual carbon" goal; by optimizing the access capacity and layout of distributed photovoltaic, the need for grid upgrades and renovations can be reduced, and the construction and operation and maintenance costs of the grid can be lowered. At the same time, the widespread application of distributed photovoltaic can reduce dependence on traditional fossil fuels, reduce energy costs, and improve energy utilization efficiency.

[0091] In one feasible implementation, step 120 in the above embodiments, which determines the access voltage of each node at time t based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power, and maximum voltage of all nodes at time t, includes:

[0092] Using formula Determine the access voltage of each node at time t;

[0093] Among them, R U,m,t R is the access voltage of the m-th node at time t. U,0 The voltage at the beginning of the preset region is M, where M is the total number of nodes and R is R. P,min,y,t Let R be the minimum nodal active power of the y-th node at time t. P,pv,y Let R be the preset access capacity of the y-th node. If the y-th node has no preset access capacity, then R... P,pv,y =0, R y R is the resistance value between the y-th node and the (y-1)-th node. Q,min,y,t Let X be the minimum nodal reactive power of the y-th node at time t. y R is the reactance between the y-th node and the (y-1)-th node. U,max,x-1,t Let R be the maximum node voltage of the (x-1)th node at time t. If x = 1, then R U,max,x-1,t =R U,0 .

[0094] It should be noted that the starting voltage of the preset area is the starting voltage of the transformer in the preset area.

[0095] In this embodiment of the application, a rigorous mathematical formula is provided for the access voltage of each node at time t. The rigor of the mathematical logic ensures the accuracy of the calculated access voltage. Furthermore, by showing the above-mentioned calculation formula for the access voltage, it is convenient for technicians to refer to, understand, and calculate.

[0096] Furthermore, by adopting the preferred calculation formula for the access voltage provided in this application, this method not only considers the complex network topology and line electrical parameters within the distribution area, but also incorporates the actual power load characteristics at different times. This allows for a more accurate calculation of the voltage of each node after accessing distributed photovoltaic power. This calculation method fully considers the mutual influence between various factors such as voltage, current, and power, avoiding power quality problems such as voltage exceeding limits that may occur with traditional methods.

[0097] In one feasible implementation, step 130 in the above embodiments, which determines the (k+1)th access voltage of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node, includes:

[0098] Using formula Determine the (k+1)th connected voltage of each node at time t;

[0099] in, Let Y be the voltage connected to the m-th node at time t (k+1). mm Let R be the self-admittance between the m-th node and the m-th node. P,min,m,t R is the minimum nodal active power of the m-th node at time t. P,pv,m R represents the preset access capacity for the m-th node. If the m-th node does not have a preset access capacity, then R... P,pv,m =0, j is the imaginary unit of the complex number, R Q,min,m,t Let be the minimum nodal reactive power of the m-th node at time t. Let Y be the conjugate of the k-th access voltage of the m-th node at time t, where M is the total number of nodes. If m = x, then Y... mx Let Y be the self-admittance between the m-th node and the x-th node. If m ≠ x, then Y mx Let be the mutual admittance between the m-th node and the x-th node. Let k be the voltage connected to the x-th node at time t.

[0100] In this embodiment of the application, a rigorous mathematical formula is provided for the (k+1)th access voltage of each node at time t. The rigor of the mathematical logic ensures the accuracy of the calculated (k+1)th access voltage. Furthermore, by preferably showing the above-mentioned formula for calculating the (k+1)th access voltage, it is convenient for technicians to refer to, understand, and calculate.

[0101] Furthermore, by adopting the calculation formula for the (k+1)th access voltage provided in this application, this formula fully considers the complex network topology within the distribution area. By introducing self-admittance and mutual admittance, it accurately describes the electrical connections between each node. This approach enables the evaluation method to more accurately reflect the actual operation of the power grid, improving the accuracy of the evaluation. Moreover, the formula incorporates the actual power load characteristics at different times, including the minimum active power and minimum reactive power of the nodes. These parameters can reflect the changes in power demand of the power grid at different time periods. By considering these changes, the evaluation method can more flexibly adapt to the power demand of different regions, providing a scientific basis for the optimal configuration of distributed photovoltaic systems. Furthermore, the formula also adopts an iterative calculation method, determining the access voltage of each node by continuously approximating the true value. This iterative method can gradually reduce errors and improve the accuracy of the calculation. At the same time, by setting preset iteration conditions to determine whether the iteration has converged, the stability and reliability of the calculation process are ensured.

[0102] In one feasible implementation, steps 140 and 150 in the above embodiments are based on the preset iteration condition that the absolute value of the difference between the k-th access voltage and the (k+1)-th access voltage of each node at time t is less than the iteration voltage difference threshold.

[0103] The iterative voltage difference threshold can be obtained and set by the operator based on extensive experience, experiments, or statistics.

[0104] In some embodiments, the iterative voltage difference threshold is preferably set to 0.2.

[0105] In this embodiment of the application, by setting an iterative voltage difference threshold as a preset iteration condition, the distributed photovoltaic access capacity assessment method can improve the certainty, predictability, robustness, and stability of the assessment process while ensuring assessment accuracy. This is of great significance for promoting the development of high-quality distribution networks and ensuring the safe and reliable operation of the distribution area power grid.

[0106] Understandably, by setting a clear iterative voltage difference threshold, it is possible to clearly define when the iteration process can stop. That is, when the change in the access voltage of all nodes in two consecutive iterations is less than the threshold, the iteration is considered to be close enough to the true value and can be stopped. This setting makes the evaluation process more deterministic and predictable, and the setting of the iterative voltage difference threshold can be adjusted according to actual needs to adapt to different evaluation accuracy requirements. For example, when a higher accuracy evaluation is required, a smaller iterative voltage difference threshold can be selected to obtain a more accurate access voltage value, while when the accuracy requirement is not so strict, a slightly larger threshold can be selected to save computation time and resources. Furthermore, this setting also helps to improve the robustness and stability of the evaluation method, because in practical applications, the operating state of the power grid may be affected by various factors and change, causing fluctuations in the calculated access voltage. By setting an iterative voltage difference threshold, it can be ensured that even under such circumstances, the evaluation method can stably converge to a reasonable solution, thereby avoiding misjudgment or misoperation due to computational instability.

[0107] In one feasible implementation, step 160 in the above embodiment, which determines the access evaluation result based on the target access voltage and preset power supply voltage range of all nodes at all times, includes: if the target access voltage of each node at each time is within the preset power supply voltage range, then the preset access capacity of distributed photovoltaic at at least one node that meets the access preset area is taken as the access evaluation result; otherwise, the preset access capacity of distributed photovoltaic at at least one node that does not meet the access preset area is taken as the access evaluation result.

[0108] In some embodiments, the power supply voltage standard set by the State Power Supply Bureau can be obtained, and then 0.9 times the power supply voltage standard can be used as the first power supply voltage, and 1.07 times the power supply voltage standard can be used as the second power supply voltage. A preset power supply voltage range can be determined based on the first power supply voltage and the second power supply voltage. The power supply voltage standard can be 220V.

[0109] In this embodiment, the access assessment result is determined by comparing the target access voltage with the preset supply voltage range. This not only improves the accuracy and reliability of the assessment, but also fully considers the actual operation of the power grid and the changes in the characteristics of the power load. It has high flexibility and adaptability, which is of great significance for promoting the development of high-quality distribution networks and ensuring the safe and reliable operation of the distribution area power grid. At the same time, the implementation of this step also provides a scientific basis for the optimized configuration of distributed photovoltaic systems, which helps to realize the widespread application of clean energy and the green transformation of the energy structure.

[0110] Understandably, by comparing the target access voltage of each node at each moment with the preset supply voltage range, it is possible to accurately determine whether the access of distributed photovoltaic (PV) power will affect the voltage stability of the power grid. If the target access voltage of all nodes is within the preset supply voltage range, it indicates that the access capacity of distributed PV is reasonable and will not pose a threat to the safe operation of the power grid. Conversely, if the target access voltage of any node exceeds the preset supply voltage range, then the access capacity of distributed PV needs to be reassessed to ensure the safety and stability of the power grid. This assessment method fully considers the actual operation of the power grid and the changes in electricity load characteristics. By introducing the actual electricity load characteristics at different times, the assessment method can more accurately reflect the voltage situation of the power grid at different time periods, thereby avoiding misjudgments or omissions that may be caused by traditional methods. Furthermore, this assessment method also has high flexibility and adaptability. The preset supply voltage range can be adjusted according to actual needs to adapt to different assessment accuracy and voltage stability requirements. At the same time, the assessment method can also consider other factors affecting the voltage stability of the power grid, such as reactive power compensation and line losses, to further improve the accuracy and reliability of the assessment.

[0111] In one feasible implementation, step 110 in the above embodiments, obtaining the minimum node active power, minimum node reactive power, and maximum node voltage of each node in the preset area at time t, includes: obtaining the node active power, node reactive power, and node voltage of each node in the preset area at time t each day; determining the minimum node active power of each node at time t based on the node active power of each node at time t across all days; determining the minimum node reactive power of each node at time t based on the node reactive power of each node at time t across all days; and determining the maximum node voltage of each node at time t based on the node voltage of each node at time t across all days.

[0112] In some embodiments, formulas can be used Determine the minimum active power, minimum reactive power, and maximum node voltage of each node at time t; where R P,min,m,t Let R be the minimum nodal active power of the m-th node at time t, and min() be the minimum value. P,m,n,t Let R be the node active power of the m-th node at time t on day n, where N is the total number of days and R is the node active power of the m-th node. Q,min,m,t R is the minimum nodal reactive power of the m-th node at time t. Q,m,n,t Let R be the node reactive power of the m-th node at time t on day n. U,max,m,t R is the maximum node voltage of the m-th node at time t. U,m,n,tLet be the node voltage of the m-th node at time t on day n.

[0113] In this embodiment, by collecting and comparing the power parameters of each node at time t on multiple days, the minimum active power, minimum reactive power, and maximum voltage of each node at that time can be determined more accurately. This helps to more accurately assess the impact of distributed photovoltaic access on the power grid of the distribution area, ensuring the accuracy of the assessment results. Moreover, this method assesses all time points (time t), thereby enabling analysis of the electricity load characteristics for different time periods. This enhances the flexibility of the assessment method, allowing it to adapt to changes in electricity demand in different regions and time periods.

[0114] In one feasible implementation, obtaining the node active power, node reactive power, and node voltage of each node in the preset area at time t of each day in the above embodiments includes: obtaining the historical active power, historical reactive power, and historical voltage of each user in the preset area at time t of each day, as well as the topology diagram of the preset area; performing data cleaning on the historical active power, historical reactive power, and historical voltage of each user at time t of each day to obtain the standard active power, standard reactive power, and standard voltage of each user at time t of each day; merging user nodes according to the topology diagram to obtain multiple nodes; and determining the node active power, node reactive power, and node voltage of each node at time t of each day based on the standard active power, standard reactive power, and standard voltage of all users corresponding to each node at time t of each day.

[0115] In the embodiments of this application, the above processing steps not only improve data accuracy and evaluation efficiency, but also enhance the flexibility and adaptability of the evaluation method, providing a scientific basis for the optimized configuration of distributed photovoltaic systems, and helping to promote the development of high-quality distribution networks and the safe and reliable operation of the distribution area power grid.

[0116] Understandably, this approach offers several advantages: First, it improves data accuracy. Data cleaning removes outliers and duplicates, ensuring the accuracy and reliability of subsequent analyses. This is crucial for assessing the impact of distributed photovoltaic (PV) grid integration on the local power grid. Second, it simplifies the grid model. Node merging simplifies the grid model, reducing computational load while preserving key grid characteristics. This makes the assessment process more efficient and ensures accurate results. Third, it adapts to different time periods. This implementation considers power parameters at time t each day, enabling analysis of load characteristics across different time periods. This enhances the flexibility of the assessment method, allowing it to adapt to varying electricity demand in different regions and time periods. Fourth, it provides a foundation for accurate assessment. By collecting and processing power parameters for each node at time t on multiple days, the minimum active power, minimum reactive power, and maximum voltage of each node at that time can be determined more accurately. This provides a solid foundation for subsequent assessments of the impact of distributed PV grid integration on the local power grid.

[0117] In one feasible implementation, determining the node active power, node reactive power, and node voltage at time t of each day based on the standard active power, standard reactive power, and standard voltage of all users corresponding to each node at time t of each day includes:

[0118] Using formula Determine the active power and reactive power of each node at time t each day;

[0119] Using formula Determine the node voltage of each node at time t each day;

[0120] Where, if r = P, then R r,m,n,t Let R be the node active power of the m-th node at time t on day n. r ′ ,i,n,t Let R be the standard active power of the i-th user at time t on day n. If r = Q, then R r,m,n,t Let R be the node reactive power of the m-th node at time t on day n. r ′ ,i,n,t Let I be the standard reactive power of the i-th user at time t on day n. m R represents the total number of users at the m-th node. U,m,n,t Let R′ be the node voltage of the m-th node at time t on day n. U,i,n,t Let be the standard voltage for the i-th user at time t on day n.

[0121] In this application embodiment, a rigorous mathematical formula is provided for the active power, reactive power, and voltage of each node at time t each day. The rigor of the mathematical logic ensures the accuracy of the calculated active power, reactive power, and voltage. Furthermore, by preferentially showing the above-mentioned calculation formulas for active power, reactive power, and voltage, it is convenient for technicians to refer to, understand, and calculate.

[0122] Furthermore, by adopting the calculation formulas for node active power, node reactive power, and node voltage provided in the above-mentioned preferred application, the node active power, node reactive power, and node voltage at time t of each day can be accurately calculated, which can more accurately reflect the operating status of the distribution grid in different time periods. This helps to more accurately assess the impact of distributed photovoltaic access on the distribution grid and ensure the accuracy of the assessment results.

[0123] In one feasible implementation, the above embodiments involve data cleaning of the historical active power, historical reactive power, and historical voltage for each user at time t each day to obtain the standard active power, standard reactive power, and standard voltage for each user at time t each day. This includes: determining the average active power, average reactive power, and average voltage for each user at time t based on the historical active power, historical reactive power, and historical voltage for each user across all days; determining the active power variance, reactive power variance, and voltage variance for each user at time t based on the average active power, average reactive power, and average voltage for each user at time t, as well as the historical active power, historical reactive power, and historical voltage for each user across all days at time t; and for each user's historical active power, historical reactive power, and historical voltage at time t each day, if the absolute value of the difference between the historical active power of the i-th user at time t on day n and the average active power at the corresponding time is greater than a preset multiple of the active power variance at the corresponding time, then determining that the i-th user... If the historical active power of user i at time t on day n is an outlier, the historical active power of user i at time t on day n is corrected to the average active power of user i at time t. If the absolute value of the difference between the historical reactive power of user i at time t on day n and the average reactive power at the corresponding time is greater than a preset multiple of the reactive power variance at the corresponding time, then the historical reactive power of user i at time t on day n is determined to be an outlier, and the reactive power of user i at time t on day n is corrected. The power is corrected to the average reactive power of the i-th user at time t. If the absolute value of the difference between the historical voltage of the i-th user at time t on day n and the average voltage at the corresponding time is greater than a preset multiple of the voltage variance at the corresponding time, then the historical voltage of the i-th user at time t on day n is determined to be an abnormal value, and the voltage of the i-th user at time t on day n is corrected to the average voltage of the i-th user at time t, so as to obtain the standard active power, standard reactive power and standard voltage of each user at time t on each day.

[0124] The preset multiplier can be obtained and set by the operator based on a large amount of experience, experiments or statistics.

[0125] In some embodiments, the preset multiple is preferably set to 3.

[0126] In this embodiment of the application, by cleaning the historical active power, historical reactive power and historical voltage of each user at time t every day, a more accurate and stable data foundation can be obtained, which provides a strong guarantee for subsequent distributed photovoltaic access capacity assessment. This not only improves the accuracy of the assessment results, but also enhances the adaptability and efficiency of the assessment method, and provides strong support for promoting the development of high-quality distribution networks and the safe and reliable operation of the distribution area power grid.

[0127] Understandably, data cleaning improves data quality by calculating the average active power, average reactive power, and average voltage for each user at time t. This provides typical power parameters for all times, serving as a benchmark for subsequent analysis. Using variance to identify outliers effectively removes abnormal data caused by equipment failures, data acquisition errors, etc., thus improving data accuracy and reliability. It also enhances data stability by correcting outliers to average values, ensuring the stability and consistency of the data over time. This is crucial for subsequent power flow analysis and voltage stability assessments; a stable data foundation makes assessment results more reliable and reduces uncertainty caused by data fluctuations. Finally, it optimizes analysis efficiency by automating large-scale data processing, significantly improving analysis efficiency. Reducing interference from outlier data makes subsequent iterative calculations smoother, reducing computation time and resource consumption; improving assessment accuracy: accurate data is the foundation for assessing distributed photovoltaic (PV) grid connection capacity. Data cleaning ensures that the data input into the assessment model is accurate and reliable, thereby improving the accuracy of the assessment results. Accurate assessment results can provide a scientific basis for the optimal configuration of distributed PV systems, ensuring the safe and reliable operation of the power grid in the distribution area; enhancing the adaptability of the assessment method: the data cleaning process takes into account the fluctuations in power parameters of different users at time t each day, and identifies outliers through variance analysis. This allows the assessment method to adapt to the electricity consumption characteristics and demand changes of different users. A highly adaptable assessment method can better serve the electricity demand of different regions and time periods, providing strong support for the widespread application of distributed PV systems.

[0128] In one feasible implementation, determining the average active power, average reactive power, and average voltage of each user at time t based on the historical active power, historical reactive power, and historical voltage of each user at time t across all days includes:

[0129] Using formula Determine the average active power, average reactive power, and average voltage for each user at time t.

[0130] The above embodiments, which determine the active power variance, reactive power variance, and voltage variance of each user at time t based on the average active power, average reactive power, and average voltage of each user at time t across all days, include:

[0131] Using formula Determine the active power variance, reactive power variance, and voltage variance for each user at time t.

[0132] Where, if r = P, then Let R be the average active power of the i-th user at time t. r,i,n,t Let δ be the historical active power of the i-th user at time t on day n. r,i,t Let r = Q, then... Let R be the average reactive power of the i-th user at time t. r,i,n,t Let δ be the historical reactive power of the i-th user at time t on day n. r,i,t Let r = U, then... Let R be the average voltage of the i-th user at time t. r,i,n,t Let δ be the historical voltage of the i-th user at time t on day n. r,i,t Let N be the voltage variance of the i-th user at time t, and N be the total number of days.

[0133] In this application embodiment, a rigorous mathematical formula is provided for the average active power, average reactive power, and average voltage of each user at time t, as well as the variances of active power, reactive power, and voltage. The rigor of the mathematical logic ensures the accuracy of the calculated average active power, average reactive power, and average voltage, as well as the variances of active power, reactive power, and voltage. Furthermore, by preferably showing the calculation formulas for the above-mentioned average active power, average reactive power, and average voltage, as well as the variances of active power, reactive power, and voltage, it is convenient to provide technical personnel with reference, understanding, and calculation.

[0134] Furthermore, by employing the calculation formulas for the average active power, average reactive power, and average voltage, as well as the variances of active power, reactive power, and voltage, provided in the preferred embodiment of this application, the average active power, average reactive power, and average voltage, as well as the variances of active power, reactive power, and voltage, for each user at time t can be accurately calculated. This further improves the accuracy and reliability of the data, which helps to more accurately assess the impact of distributed photovoltaic access on the power grid of the distribution area and ensures the accuracy of the assessment results.

[0135] The following is a specific implementation example, taking the calculation, evaluation and analysis of the access capacity of a certain photovoltaic distributed system in a certain area as an example.

[0136] Please see Figure 2 The diagram shows a simplified distribution network in this embodiment. The transformer capacity is 315kVA, the number of users is 73, the overhead line is used, and the conductor type is LGJ-50. The simplified distribution network contains 18 nodes, and it is planned to connect distributed photovoltaic power at nodes 5, 12 and 16.

[0137] Under the premise that the access voltage of each node in the transformer area is maintained within the preset power supply voltage range, the maximum photovoltaic capacity that can be connected to the three nodes is calculated and determined using the evaluation method of this application.

[0138] First, power parameters of each node in the distribution area, including node active power, node reactive power, and node voltage, are collected at preset time intervals (15 minutes, i.e., 96 sampling points per day). Then, data cleaning is performed based on the topology results and historical user data. On the basis of data cleaning, iterative calculations are performed to determine the access voltage of each node at different times, and the target access voltage is derived accordingly. Finally, the target access voltage of all nodes at all times is compared with the preset power supply voltage range to obtain the access evaluation results.

[0139] The results show that, under the condition that the voltage of each node in the distribution area meets the preset power supply voltage range, the maximum photovoltaic capacity that can be connected to nodes 5, 12 and 16 is 45kW, 30kW and 23kW respectively. This result not only provides a scientific basis for the optimized configuration of distributed photovoltaic systems, but also effectively prevents voltage over-limit problems caused by photovoltaic access, thereby ensuring the safe and reliable operation of the power grid in the distribution area.

[0140] As can be seen, the evaluation method of this application, by introducing the actual power load characteristics at different times and considering the complex network topology and line electrical parameters within the distribution area, can more accurately determine the upper limit of photovoltaic capacity suitable for each node in the distribution area. The results of this specific implementation example of this application also verify the effectiveness and accuracy of this application.

[0141] In a second aspect, this application provides a distributed photovoltaic grid connection capacity assessment device.

[0142] Please see Figure 3 This is a schematic diagram of a distributed photovoltaic grid connection capacity assessment device according to an embodiment of this application. The device 310 includes:

[0143] The acquisition module 311 is used to acquire the preset access capacity of distributed photovoltaic in the preset area at at least one node, the resistance value and reactance value of each two adjacent nodes in the preset area, and the minimum active power, minimum reactive power and maximum voltage of each node in the preset area at time t, where t is a positive integer and the initial value of t is 1.

[0144] The initial determination module 312 is used to determine the access voltage of each node at time t based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power and maximum voltage of all nodes at time t, and to use the access voltage as the first access voltage at time t.

[0145] The iterative determination module 313 is used to determine the (k+1)th access voltage of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node, where k is a positive integer and the initial value of k is 1.

[0146] The time iteration module 314 is used to take the k+1 access voltage as the target access voltage at time t when the absolute value of the difference between the kth access voltage and the (k+1)th access voltage of each node at time t satisfies the preset iteration condition, and then return to execute the steps of obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at time t, until t equals the total number of time points.

[0147] The voltage iteration module 315 is used to, when there is at least one node at time t whose absolute value of the difference between the kth access voltage and the (k+1th access voltage) does not meet the preset iteration condition, let k = k+1, and return to execute the step of determining the (k+1th access voltage) of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node.

[0148] The access evaluation module 316 is used to determine the access evaluation result based on the target access voltage and preset power supply voltage range of all nodes at all times.

[0149] In this embodiment, the relevant contents of the acquisition module 311, initial determination module 312, iterative determination module 313, time iteration module 314, voltage iteration module 315, and access evaluation module 316 can be found in the following references. Figure 1 The contents of the illustrated embodiments will not be repeated here.

[0150] It should be noted that the device 310 of this application also includes other modules. It is understood that the method of this application and the device 310 have a one-to-one correspondence. Therefore, the other modules of the device 310 of this application are the contents corresponding to the method of this application in the above embodiments.

[0151] In this embodiment, the system first obtains the preset access capacity of distributed photovoltaic (PV) systems at at least one node in a preset area, as well as the resistance and reactance values ​​of every two adjacent nodes in the preset area. It also obtains the minimum active power, minimum reactive power, and maximum voltage of each node in the preset area at time t. Then, through iterative calculation, the target access voltage is determined. Finally, the target access voltage of all nodes at all times is compared with the preset supply voltage range to obtain the access evaluation result. This device not only considers the complex network topology and electrical parameters within the distribution area but also incorporates the actual power load characteristics at different times and performs detailed analysis. This allows for a more accurate determination of the upper limit of PV capacity suitable for each node within the distribution area, providing a scientific basis for the optimized configuration of distributed PV systems. It effectively prevents voltage exceedance issues caused by PV access, thereby ensuring the safe and reliable operation of the distribution area's power grid. This not only significantly improves the prediction accuracy of the impact of distributed PV access but also provides strong technical support for promoting the development of high-quality distribution networks in China.

[0152] In a third aspect, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform a distributed photovoltaic access capacity assessment method as described in the above-described method embodiments.

[0153] In a fourth aspect, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs a distributed photovoltaic access capacity assessment method according to the above-described method embodiments.

[0154] Figure 4 The diagram illustrates the internal structure of a computer device in some embodiments. This computer device may specifically be a terminal, a server, or a gateway. Figure 4 As shown, the computer device includes a processor, memory, and network interface connected via a system bus.

[0155] The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When executed by a processor, this computer program causes the processor to perform the steps in the above method embodiments. The internal memory may also store a computer program, which, when executed by a processor, causes the processor to perform the steps in the above method embodiments. Those skilled in the art will understand that... Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0156] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods.

[0157] Any references to memory, storage, database, or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0158] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for assessing the capacity of distributed photovoltaic power grid connection, characterized in that, The method includes: The system obtains the preset access capacity of distributed photovoltaic power at at least one node in the preset area, the resistance and reactance values ​​of every two adjacent nodes in the preset area, and the minimum active power, minimum reactive power and maximum voltage of each node in the preset area at time t, where t is a positive integer and the initial value of t is 1. Based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power and maximum voltage of all nodes at time t, the access voltage of each node at time t is determined, and the access voltage is taken as the first access voltage at time t. The k+1th access voltage of each node at time t is determined based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node, where k is a positive integer and the initial value of k is 1. When the absolute value of the difference between the kth access voltage and the (k+1th access voltage) of each node at time t satisfies the preset iteration condition, the (k+1th access voltage) is taken as the target access voltage at time t. Let t = t+1, and return to the step of obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset region at time t, until t equals the total number of time points. If the absolute value of the difference between the kth access voltage and the (k+1th access voltage) of at least one node at time t does not satisfy the preset iteration condition, let k = k+1, and return to the step of determining the (k+1th access voltage) of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node. The access evaluation results are determined based on the target access voltage and preset power supply voltage range of all nodes at all times.

2. The method according to claim 1, characterized in that, The step of determining the access voltage of each node at time t based on the preset access capacity of at least one node, the resistance and reactance values ​​of all two adjacent nodes, and the minimum active power, minimum reactive power, and maximum voltage of all nodes at time t includes: Using formula Determine the access voltage of each node at time t; Among them, R U,m,t R is the access voltage of the m-th node at time t. U,0 The voltage at the beginning of the preset region is M, where M is the total number of nodes and R is R. P,min,y,t Let R be the minimum nodal active power of the y-th node at time t. P,pv,y Let R be the preset access capacity of the y-th node. If the y-th node has no preset access capacity, then R... P,pv,y =0, R y R is the resistance value between the y-th node and the (y-1)-th node. Q,min,y,t Let X be the minimum nodal reactive power of the y-th node at time t. y R is the reactance between the y-th node and the (y-1)-th node. U,max,x-1,t Let R be the maximum node voltage of the (x-1)th node at time t. If x = 1, then R U,max,x-1,t =R U,0 .

3. The method according to claim 1, characterized in that, The step of determining the (k+1)th access voltage of each node at time t based on the kth access voltage of each node at time t, the minimum active power of the node, the minimum reactive power of the node, and the preset access capacity of at least one node includes: Using formula Determine the (k+1)th connected voltage of each node at time t; in, Let Y be the voltage connected to the m-th node at time t (k+1). mm Let R be the self-admittance between the m-th node and the m-th node. P,min,m,t R is the minimum nodal active power of the m-th node at time t. P,pv,m R represents the preset access capacity for the m-th node. If the m-th node does not have a preset access capacity, then R... P,pv,m =0, j is the imaginary unit of the complex number, R Q,min,m,t Let be the minimum nodal reactive power of the m-th node at time t. Let Y be the conjugate of the k-th access voltage of the m-th node at time t, where M is the total number of nodes. If m = x, then Y... mx Let Y be the self-admittance between the m-th node and the x-th node. If m ≠ x, then Y mx Let be the mutual admittance between the m-th node and the x-th node. Let k be the voltage connected to the x-th node at time t.

4. The method according to claim 1, characterized in that, The preset iteration condition is that the absolute value of the difference between the k-th access voltage and the (k+1)-th access voltage of each node at time t is less than the iteration voltage difference threshold.

5. The method according to claim 1, characterized in that, The process of determining the access evaluation result based on the target access voltage and preset power supply voltage range of all nodes at all times includes: If the target access voltage of each node at each time is within the preset power supply voltage range, then the access evaluation result is that the preset access capacity of the distributed photovoltaic system at at least one node meets the access requirements of the preset area; otherwise, the access evaluation result is that the preset access capacity of the distributed photovoltaic system at at least one node does not meet the access requirements of the preset area.

6. The method according to claim 1, characterized in that, The step of obtaining the minimum node active power, minimum node reactive power, and maximum node voltage of each node in the preset region at time t includes: Obtain the active power, reactive power, and voltage of each node in the preset area at time t each day; The minimum node active power at time t is determined based on the node active power of each node at time t across all days. The minimum node reactive power of each node at time t is determined based on the node reactive power of each node at time t across all days. The maximum node voltage at time t is determined based on the node voltage of each node at time t across all days.

7. The method according to claim 6, characterized in that, The step of obtaining the node active power, node reactive power, and node voltage of each node in the preset area at time t each day includes: Obtain the historical active power, historical reactive power, and historical voltage of each user in the preset area at time t each day, as well as the topology diagram of the preset area; For each user, the historical active power, historical reactive power, and historical voltage at time t of each day are cleaned to obtain the standard active power, standard reactive power, and standard voltage for each user at time t of each day. The user nodes are merged according to the topology diagram to obtain multiple nodes; The node active power, node reactive power, and node voltage at time t of each day are determined based on the standard active power, standard reactive power, and standard voltage of all users corresponding to each node at time t of each day.

8. The method according to claim 7, characterized in that, The process of determining the node active power, node reactive power, and node voltage at time t of each day based on the standard active power, standard reactive power, and standard voltage of all users corresponding to each node at time t of each day includes: Using formula Determine the active power and reactive power of each node at time t each day; Using formula Determine the node voltage of each node at time t each day; Where, if r = P, then R r,m,n,t Let R be the node active power of the m-th node at time t on day n. r ′ ,i,n,t Let R be the standard active power of the i-th user at time t on day n. If r = Q, then R r,m,n,t Let R be the node reactive power of the m-th node at time t on day n. r ′ ,i,n,t Let I be the standard reactive power of the i-th user at time t on day n. m R represents the total number of users at the m-th node. U,m,n,t Let R′ be the node voltage of the m-th node at time t on day n. U,i,n,t Let be the standard voltage for the i-th user at time t on day n.

9. The method according to claim 7, characterized in that, The process involves cleaning the historical active power, historical reactive power, and historical voltage for each user at time t each day to obtain the standard active power, standard reactive power, and standard voltage for each user at time t each day, including: The average active power, average reactive power, and average voltage of each user at time t are determined based on the historical active power, historical reactive power, and historical voltage of each user at time t on all days. The variances of active power, reactive power, and voltage for each user at time t are determined based on the average active power, average reactive power, and average voltage for each user at time t across all days, as well as the historical active power, historical reactive power, and historical voltage for each user at time t. For each user's historical active power, historical reactive power, and historical voltage at time t on each day, if the absolute value of the difference between the historical active power of user i at time t on day n and the average active power at that time is greater than a preset multiple of the variance of active power at that time, then the historical active power of user i at time t on day n is determined to be an outlier, and the historical active power of user i at time t on day n is corrected to the average active power of user i at time t. If the absolute value of the difference between the historical reactive power of user i at time t on day n and the average reactive power at that time is greater than a preset multiple of the variance of reactive power at that time... If the historical reactive power of user i at time t on day n is determined to be an outlier, the reactive power of user i at time t on day n is corrected to the average reactive power of user i at time t. If the absolute value of the difference between the historical voltage of user i at time t on day n and the average voltage at the corresponding time is greater than a preset multiple of the voltage variance at the corresponding time, the historical voltage of user i at time t on day n is determined to be an outlier, and the voltage of user i at time t on day n is corrected to the average voltage of user i at time t, so as to obtain the standard active power, standard reactive power and standard voltage of each user at time t on each day.

10. The method according to claim 9, characterized in that, The determination of each user's average active power, average reactive power, and average voltage at time t based on each user's historical active power, historical reactive power, and historical voltage at time t across all days includes: Using formula Determine the average active power, average reactive power, and average voltage for each user at time t. The determination of the active power variance, reactive power variance, and voltage variance for each user at time t, based on the average active power, average reactive power, and average voltage of each user at time t across all days, includes: Using formula Determine the active power variance, reactive power variance, and voltage variance for each user at time t. Where, if r = P, then Let R be the average active power of the i-th user at time t. r,i,n,t Let δ be the historical active power of the i-th user at time t on day n. r,i,t Let r = Q, then... Let R be the average reactive power of the i-th user at time t. r,i,n,t Let δ be the historical reactive power of the i-th user at time t on day n. r,i,t Let r = U, then... Let R be the average voltage of the i-th user at time t. r,i,n,t Let δ be the historical voltage of the i-th user at time t on day n. r,i,t Let N be the voltage variance of the i-th user at time t, and N be the total number of days.

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