Distributed photovoltaic access capacity assessment method

Abstract

The embodiment of the invention discloses a distributed photovoltaic access capacity assessment method, which comprises the following steps of: firstly, acquiring a preset access capacity of distributed photovoltaic in a preset area at at least one node, and a resistance value and a reactance value of every two adjacent nodes in the preset area; and obtaining the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the t-th moment, then determining a target access voltage through iterative calculation, and finally comparing the target access voltages of all nodes at all moments with a preset power supply voltage range to determine the target access voltage of all nodes at all moments. Obtaining an access evaluation result; the method not only considers the complex network topology structure and line electrical parameter factors in the transformer area, but also introduces the actual electrical load characteristics at different moments, can more accurately determine the photovoltaic capacity upper limit suitable for the access of each node in the transformer area, effectively prevents the voltage out-of-limit problem caused by photovoltaic access, and improves the reliability of the transformer area. Therefore, safe and reliable operation of the district power grid is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a distributed photovoltaic access capacity assessment method. Background Art

[0002] In the context of China's efforts to promote the development of high-quality distribution networks, the deployment scale of distributed photovoltaic power generation systems in low-voltage distribution networks (substations) is continuing to expand as a key link in promoting the application of clean energy. With the improvement of low-voltage substation data collection technology, the frequency of data collection including voltage, current, power, etc. is increasing, and the low-voltage power grid diagram is constantly improving. These advances should provide a more solid foundation for the evaluation of substation adjustable capacity.

[0003] However, the traditional distributed photovoltaic access capacity assessment method mainly relies on the user's power load historical data and the rated capacity of the substation transformer for simple estimation. Although this method can ensure the safety and stability of substation operation to a certain extent, it has obvious limitations.

[0004] Specifically, the traditional distributed photovoltaic access capacity assessment method fails to fully consider the impact of various complex factors within the substation area. This means that even if the photovoltaic capacity is connected within the theoretically calculated safety range, it may cause power quality problems such as overvoltage due to unforeseen changes in power flow, thus posing a threat to the overall stable operation of the substation area power grid. The existence of this limitation highlights the inadequacy of current technical means in assessing the access capacity of distributed photovoltaics. Summary of the invention

[0005] Based on this, it is necessary to propose a distributed photovoltaic access capacity assessment method to address the above problems. It not only takes into account the complex network topology and line electrical parameter factors within the substation, but also introduces the actual power load characteristics at different times. It can more accurately determine the upper limit of photovoltaic capacity suitable for access to each node in the substation, and effectively prevent the voltage over-limit problem caused by photovoltaic access, thereby ensuring the safe and reliable operation of the substation power grid.

[0006] To achieve the above object, the present invention provides a distributed photovoltaic access capacity assessment method in a first aspect, the method comprising:

[0007] Obtaining the preset access capacity of distributed photovoltaics in at least one node in a preset area, and the resistance and reactance values ​​of each two adjacent nodes in the preset area, and obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at the tth moment, where t is a positive integer and the initial value of t is 1;

[0008] Determine the access voltage of each node at the tth moment according to the preset access capacity of at least one node, the resistance value and the reactance value of all two adjacent nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment, and use the access voltage as the first access voltage at the tth moment;

[0009] Determine the k+1th access voltage of each node at the tth moment according to the kth access voltage of each node at the tth moment, the minimum node active power and the minimum node reactive power, 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 the tth moment satisfies the preset iteration condition, the k+1th access voltage is used as the target access voltage at the tth moment, and t=t+1 is set, and the step of obtaining the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth moment is returned until t is equal to the total number of moments;

[0011] When there is at least one node whose absolute value of the difference between the kth access voltage and the k+1th access voltage at the tth time 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 the tth time according to the kth access voltage of each node at the tth time, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node;

[0012] The access assessment result is determined according to the target access voltage of all nodes at all times and the preset power supply voltage range.

[0013] Optionally, determining the access voltage of each node at the tth moment according to the preset access capacity of at least one node, the resistance value and the reactance value of all two adjacent nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment includes:

[0014] Using the formula Determine the access voltage of each node at the tth moment;

[0015] Among them, R U,m,t is the access voltage of the mth node at the tth moment, R U,0 is the voltage at the head end of the preset area, M is the total number of nodes, R P,min,y,t is the minimum node active power of the yth node at the tth moment, R P,pv,y is the preset access capacity of the yth node. If the yth node has no preset access capacity, then R P,pv,y=0, R y is the resistance between the yth node and the y-1th node, R Q,min,y,t is the minimum node reactive power of the yth node at the tth moment, X y is the reactance value between the yth node and the y-1th node, R U,max,x-1,t is the maximum node voltage of the x-1th node at the tth moment. If x=1, then R U,max,x-1,t =R U,0 .

[0016] Optionally, determining the k+1th access voltage of each node at the tth moment according to the kth access voltage of each node at the tth moment, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node includes:

[0017] Using the formula Determine the k+1th access voltage of each node at the tth time;

[0018] in, is the k+1th access voltage of the mth node at the tth time, Y mm is the self-admittance between the mth node and the mth node, R P,min,m,t is the minimum node active power of the mth node at the tth moment, R P,pv,m is the preset access capacity of the mth node. If the mth node has no preset access capacity, then R P,pv,m =0, j is the imaginary unit of the complex number, R Q,min,m,t is the minimum node reactive power of the mth node at the tth moment, is the conjugate of the kth access voltage of the mth node at the tth time, M is the total number of nodes, if m = x, then Y mx is the self-admittance between the mth node and the xth node. If m≠x, then Y mx is the mutual admittance between the mth node and the xth node, is the kth access voltage of the xth node at the tth time.

[0019] Optionally, the preset iteration condition is that the absolute value of the difference between the kth access voltage and the k+1th access voltage of each node at the tth moment is less than an iteration voltage difference threshold.

[0020] Optionally, determining the access assessment result according to the target access voltages of all nodes at all times and a preset power supply voltage range includes:

[0021] If the target access voltage of each node at each moment is within the preset power supply voltage range, the preset access capacity of the distributed photovoltaic at at least one node satisfies the access to the preset area as the access evaluation result; otherwise, the preset access capacity of the distributed photovoltaic at at least one node does not satisfy the access to the preset area as the access evaluation result.

[0022] Optionally, the obtaining of the minimum node active power, the minimum node reactive power, and the maximum node voltage of each node in the preset area at the tth moment includes:

[0023] Obtaining the node active power, node reactive power and node voltage of each node in the preset area at the t-th moment of each day;

[0024] Determine the minimum node active power of each node at the tth moment according to the node active power of each node at the tth moment of all days;

[0025] Determine the minimum node reactive power of each node at the tth moment according to the node reactive power of each node at the tth moment of all days;

[0026] The maximum node voltage of each node at the tth moment is determined according to the node voltage of each node at the tth moment of all days.

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

[0028] Obtaining the historical active power, historical reactive power and historical voltage of each user in the preset area at the t-th moment of each day, and the topological wiring diagram of the preset area;

[0029] The historical active power, historical reactive power and historical voltage of each user at the t-th moment of each day are cleaned to obtain the standard active power, standard reactive power and standard voltage of each user at the t-th moment of each day;

[0030] Merging user nodes according to the topology wiring diagram to obtain multiple nodes;

[0031] The node active power, node reactive power and node voltage of each node at the tth moment of each day are determined according to the standard active power, standard reactive power and standard voltage of all users corresponding to each node at the tth moment of each day.

[0032] Optionally, determining the node active power, node reactive power and node voltage of each node at the tth moment of each day according to the standard active power, standard reactive power and standard voltage of all users corresponding to each node at the tth moment of each day includes:

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

[0034] Using the formula Determine the node voltage of each node at the tth moment of each day;

[0035] Among them, if r = P, then R r,m,n,t is the active power of the mth node at the tth moment on the nth day, R r ' ,i,n,t is the standard active power of the ith user at the tth time on the nth day. If r = Q, then R r,m,n,t is the node reactive power of the mth node at the tth moment on the nth day, R r ' ,i,n,t is the standard reactive power of the i-th user at the t-th moment on the n-th day, I m is the total number of users of the mth node, R U,m,n,t is the node voltage of the mth node at the tth time on the nth day, R′ U,i,n,t is the standard voltage of the i-th user at the t-th moment on the n-th day.

[0036] Optionally, the data of the historical active power, historical reactive power and historical voltage of each user at the t-th moment of each day are cleaned to obtain the standard active power, standard reactive power and standard voltage of each user at the t-th moment of each day, including:

[0037] Determine the average active power, average reactive power and average voltage of each user at the tth moment according to the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days;

[0038] Determine the active power variance, reactive power variance and voltage variance of each user at the tth moment according to the average active power, average reactive power and average voltage of each user at the tth moment and the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days;

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

[0040] Optionally, determining the average active power, average reactive power and average voltage of each user at the tth moment according to the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days includes:

[0041] Using the formula Determine the average active power, average reactive power and average voltage of each user at the tth moment;

[0042] Determining the active power variance, reactive power variance and voltage variance of each user at the tth moment according to the average active power, average reactive power and average voltage of each user at the tth moment, and the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days, includes:

[0043] Using the formula Determine the active power variance, reactive power variance and voltage variance of each user at the tth moment;

[0044] Among them, if r = P, then is the average active power of the i-th user at the t-th time, R r,i,n,t is the historical active power of the ith user at the tth moment on the nth day, δ r,i,t is the active power variance of the ith user at the tth moment. If r = Q, then is the average reactive power of the ith user at the tth moment, R r,i,n,t is the historical reactive power of the ith user at the tth moment on the nth day, δ r,i,t is the reactive power variance of the ith user at the tth moment. If r = U, then is the average voltage of the ith user at the tth moment, R r,i,n,t is the historical voltage of the ith user at the tth moment on the nth day, δ r,i,t is the voltage variance of the i-th user at the t-th moment, and N is the total number of days.

[0045] To achieve the above object, the present invention provides a distributed photovoltaic access capacity assessment device in a second aspect, the device comprising:

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

[0047] An initial determination module, used to determine the access voltage of each node at the tth moment according to the preset access capacity of at least one node, the resistance value and the reactance value of all two adjacent nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment, and use the access voltage as the first access voltage at the tth moment;

[0048] an iterative determination module, configured to determine the k+1th access voltage of each node at the tth moment according to the kth access voltage of each node at the tth moment, the minimum node active power and the minimum node reactive power, 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] A time iteration module, for when the absolute value of the difference between the kth access voltage and the k+1th access voltage of each node at the tth time satisfies the preset iteration condition, taking the k+1th access voltage as the target access voltage at the tth time, setting t=t+1, and returning to execute the step of obtaining the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth time, until t is equal to the total number of times;

[0050] A voltage iteration module, configured to, when the absolute value of the difference between the kth access voltage and the k+1th access voltage of at least one node at the tth time does not satisfy the preset iteration condition, set k=k+1, and return to the step of determining the k+1th access voltage of each node at the tth time according to the kth access voltage of each node at the tth time, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node;

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

[0052] To achieve the above-mentioned object, the present invention provides in a third aspect a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the method as described in any one of the first aspects.

[0053] To achieve the above-mentioned purpose, the present invention provides a computer device in a fourth aspect, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the method as described in any one of the first aspects.

[0054] The embodiment of the present invention has the following beneficial effects: the method obtains the preset access capacity of the distributed photovoltaic in at least one node in the preset area, the resistance value and the reactance value of each adjacent two nodes in the preset area, and obtains the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth moment, t is a positive integer, and the initial value of t is 1, and then determines the access capacity of each node according to the preset access capacity of at least one node, the resistance value and the reactance value of all adjacent two nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment. The access voltage of the point at the tth moment is obtained, and the access voltage is used as the first access voltage at the tth moment. Then, the k+1th access voltage of each node at the tth moment is determined according to the kth access voltage of each node at the tth moment, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node. k is a positive integer, and the initial value of k is 1. Then, when the absolute value of the difference between the kth access voltage and the k+1th access voltage of each node at the tth moment meets the preset iteration condition, the k+1th access voltage is used as the target access voltage at the tth moment, and t=t+1 is set. Return to execute and obtain The method comprises the steps of determining the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth moment, until t is equal to the total number of moments, when the absolute value of the difference between the kth access voltage and the k+1th access voltage of at least one node at the tth moment does not meet the preset iteration condition, setting k=k+1, returning to execute the step of determining the k+1th access voltage of each node at the tth moment according to the kth access voltage, the minimum node active power and the minimum node reactive power of each node at the tth moment, and the preset access capacity of at least one node, and finally determining the access evaluation result according to the target access voltage of all nodes at all times and the preset power supply voltage range; the method not only considers the complex network topology structure and line electrical parameter factors within the substation area, but also introduces the actual power load characteristics at different times, and conducts a detailed analysis thereof, so as to more accurately determine the upper limit of the photovoltaic capacity suitable for access of each node in the substation area, provide a scientific basis for the optimal configuration of the distributed photovoltaic system, effectively prevent the voltage over-limit problem caused by photovoltaic access, thereby ensuring the safe and reliable operation of the substation area power grid, which not only significantly improves the prediction accuracy of the impact of distributed photovoltaic access, but also provides a strong technical support for promoting the development of high-quality distribution networks in China. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] in:

[0057] Figure 1 A schematic diagram of a distributed photovoltaic access capacity assessment method in an embodiment of the present application;

[0058] Figure 2 A schematic diagram of a simplified substation network in an embodiment of the present application;

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

[0060] Figure 4 1 is a diagram of the internal structure of a computer device in some embodiments. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] In the context of China's efforts to promote the development of high-quality distribution networks, the deployment scale of distributed photovoltaic power generation systems in low-voltage distribution networks (substations) is continuing to expand as a key link in promoting the application of clean energy. With the improvement of low-voltage substation data collection technology, the frequency of data collection including voltage, current, power, etc. is increasing, and the low-voltage power grid diagram is constantly improving. These advances should provide a more solid foundation for the evaluation of substation adjustable capacity.

[0063] However, the traditional distributed photovoltaic access capacity assessment method mainly relies on the user's power load historical data and the rated capacity of the substation transformer for simple estimation. Although this method can ensure the safety and stability of substation operation to a certain extent, it has obvious limitations.

[0064] Specifically, the traditional distributed photovoltaic access capacity assessment method fails to fully consider the impact of various complex factors within the substation area. This means that even if the photovoltaic capacity is connected within the theoretically calculated safety range, it may cause power quality problems such as overvoltage due to unforeseen changes in power flow, thus posing a threat to the overall stable operation of the substation area power grid. The existence of this limitation highlights the inadequacy of current technical means in assessing the access capacity of distributed photovoltaics.

[0065] In response to the above problems, the present application proposes a distributed photovoltaic access capacity assessment method, which not only takes into account the complex network topology and line electrical parameter factors within the substation, but also introduces the actual power load characteristics at different times. It can more accurately determine the upper limit of photovoltaic capacity suitable for access to each node in the substation, and effectively prevent voltage over-limit problems caused by photovoltaic access, thereby ensuring the safe and reliable operation of the substation power grid. The specific implementation principle will be described in detail in the following embodiments.

[0066] In a first aspect, the present application provides a method for evaluating distributed photovoltaic access capacity.

[0067] See also Figure 1 , is a schematic diagram of a distributed photovoltaic access capacity assessment method in an embodiment of the present application, the method comprising:

[0068] Step 110: Obtain the preset access capacity of distributed photovoltaics 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 obtain the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at the tth moment, where t is a positive integer and the initial value of t is 1.

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

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

[0071] Regarding the node division method, in some embodiments, the network topology structure of a preset area may be obtained, and the nodes may be divided according to the network topology structure.

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

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

[0074] It should be noted that after the distributed photovoltaics are connected to the preset area, they will affect the voltage of the preset area. That is, after a node in the preset area is connected to the distributed photovoltaics with a preset access capacity, it will not only affect the access voltage of the node in the preset area, but also affect the access voltage of other nodes in the preset area. The access voltage of the node will also be affected by resistance, reactance, node active power, node reactive power and node voltage. Therefore, the access voltage can be determined according to the preset access capacity, resistance value, reactance value, minimum node active power, minimum node reactive power and maximum node voltage.

[0075] It should be further explained that since the access voltages 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 access voltage is determined by the minimum node active power, the minimum node reactive power and the maximum node voltage of the node, thereby ensuring 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 can be understood that the smaller the node active power, node reactive power and node voltage of the load are, the greater the access voltage is, and when the node active power, node reactive power and node voltage of the load are minimum, the access voltage is maximum.

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

[0078] In some embodiments, the substation transformer nodes in a preset area can be used as balancing nodes to generate node voltage equations for all nodes, so as to utilize the node voltage equation to determine the k+1th access voltage based on the kth access voltage, minimum node active power, minimum node reactive power and 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 the tth moment meets the preset iteration condition, the k+1th access voltage is used as the target access voltage at the tth moment, and t=t+1 is set. Return to execute the step of obtaining the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth moment until t is equal to the total number of moments.

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

[0081] In some embodiments, the preset iteration condition can adopt the iteration condition of the existing iteration algorithm; for example, the iteration condition is satisfied when it is less than or equal to a threshold but not satisfied when it is greater than the threshold, or satisfied when it is less than the threshold but not satisfied when it is greater than or equal to the threshold, etc., which will not be repeated 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 the tth moment meets the preset iteration condition, the k+1th access voltage is used as the target access voltage at the tth moment, and t=t+1 is set. Return to step 110 in the above embodiment and start re-iteration from "obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at the tth moment" until t is equal to the total number of moments.

[0083] Step 150: When there is at least one node whose absolute value of the difference between the kth access voltage and the k+1th access voltage at the tth moment does not satisfy the preset iteration condition, set k=k+1, and return to the step of determining the k+1th access voltage of each node at the tth moment based on the kth access voltage of each node at the tth moment, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node.

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

[0085] Step 160: Determine an access assessment result according to the target access voltages of all nodes at all times and a preset power supply voltage range.

[0086] The preset power supply voltage range may be obtained and set by an operator based on a large amount of experience, experiments or statistics.

[0087] In some embodiments, the preset power supply voltage range may be determined according to the power supply voltage standard established by the State Power Supply Bureau.

[0088] In some embodiments, the access evaluation result may be determined based on a comparison result between the target access voltage of all nodes at all times and a preset supply voltage range; wherein the access evaluation result may be satisfactory for access or unsatisfactory for access.

[0089] In an embodiment of the present application, the preset access capacity of distributed photovoltaics in at least one node in a preset area, the resistance value and reactance value of each two adjacent nodes in the preset area, and the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at the tth moment are first obtained, and then the target access voltage is determined through iterative calculation. 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 result; this method not only takes into account the complex network topology and line electrical parameter factors within the substation, but also introduces the actual power load characteristics at different times and performs a detailed analysis on them. It can more accurately determine the upper limit of photovoltaic capacity suitable for access to each node in the substation, provide a scientific basis for the optimal configuration of the distributed photovoltaic system, and effectively prevent the voltage over-limit problem caused by photovoltaic access, thereby ensuring the safe and reliable operation of the substation power grid. It 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 domestic distribution networks.

[0090] In addition, the method of the present application also has the following advantages: by introducing the actual power load characteristics at different times, special attention is paid to the directionality of its power flow, ensuring that distributed photovoltaic power is consumed locally as much as possible, and avoiding the impact of distributed photovoltaic reverse flow on the power grid; by accurately evaluating the upper limit of photovoltaic access capacity of each node, grid planners can more flexibly design the layout and scale of distributed photovoltaics to adapt to changes in electricity demand in different regions and time periods, which helps to optimize the grid structure and improve the grid's absorption and dispatching capabilities for renewable energy, thereby enhancing the overall flexibility and resilience of the grid; accurate access capacity assessment helps to eliminate the concerns of grid operators and distributed photovoltaic investors about power quality issues such as voltage over-limit, 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 the realization of the "dual carbon" goal; by optimizing the access capacity and layout of distributed photovoltaics, the need for grid upgrades and renovations can be reduced, and the cost of grid construction and operation and maintenance can be reduced. At the same time, the widespread application of distributed photovoltaics can reduce dependence on traditional fossil energy, reduce energy costs, and improve energy utilization efficiency.

[0091] In a feasible implementation, step 120 in the above embodiment determines the access voltage of each node at the tth moment according to the preset access capacity of at least one node, the resistance value and the reactance value of all two adjacent nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment, including:

[0092] Using the formula Determine the access voltage of each node at the tth moment;

[0093] Among them, R U,m,t is the access voltage of the mth node at the tth moment, R U,0 is the voltage at the head end of the preset area, M is the total number of nodes, R P,min,y,t is the minimum node active power of the yth node at the tth moment, R P,pv,y is the preset access capacity of the yth node. If the yth node has no preset access capacity, then R P,pv,y =0, R y is the resistance between the yth node and the y-1th node, R Q,min,y,t is the minimum node reactive power of the yth node at the tth moment, X y is the reactance value between the yth node and the y-1th node, R U,max,x-1,t is the maximum node voltage of the x-1th node at the tth moment. If x=1, then R U,max,x-1,t =R U,0 .

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

[0095] In the embodiments of the present application, a rigorous formula for the access voltage of each node at the tth moment is provided from a mathematical perspective. The accuracy of the calculated access voltage can be ensured from the rigor of mathematical logic, and the calculation formula of the access voltage is preferably shown to provide reference, understanding and calculation for technical personnel.

[0096] In addition, by adopting the calculation formula for the access voltage preferably provided in the above-mentioned application, that is, in this way, not only the complex network topology structure and line electrical parameters within the substation are taken into account, but also the actual power load characteristics at different times are incorporated, so that the voltage of each node after connecting to distributed photovoltaics can be calculated more accurately. This calculation method fully considers the mutual influence of multiple factors such as voltage, current, and power, and avoids power quality problems such as voltage over-limit that may be caused by traditional methods.

[0097] In a feasible implementation, step 130 in the above embodiment, determining the k+1th access voltage of each node at the tth time according to the kth access voltage of each node at the tth time, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node, includes:

[0098] Using the formula Determine the k+1th access voltage of each node at the tth time;

[0099] in, is the k+1th access voltage of the mth node at the tth time, Y mm is the self-admittance between the mth node and the mth node, R P,min,m,t is the minimum node active power of the mth node at the tth moment, R P,pv,m is the preset access capacity of the mth node. If the mth node has no preset access capacity, then R P,pv,m =0, j is the imaginary unit of the complex number, R Q,min,m,t is the minimum node reactive power of the mth node at the tth moment, is the conjugate of the kth access voltage of the mth node at the tth time, M is the total number of nodes, if m = x, then Y mx is the self-admittance between the mth node and the xth node. If m≠x, then Y mx is the mutual admittance between the mth node and the xth node, is the kth access voltage of the xth node at the tth time.

[0100] In the embodiments of the present application, a rigorous formula for the k+1th access voltage of each node at the tth moment is provided from a mathematical perspective. The accuracy of the calculated k+1th access voltage can be ensured from the rigor of mathematical logic, and the calculation formula for the above-mentioned k+1th access voltage is preferably shown to provide reference, understanding and calculation for technical personnel.

[0101] In addition, by adopting the calculation formula for the k+1th access voltage provided by the above-mentioned preferred embodiment of the present application, the formula fully considers the complex network topology structure within the substation, and accurately describes the electrical connection between each node by introducing self-admittance and mutual admittance. This processing method enables the evaluation method to more accurately reflect the actual operation of the power grid and improves the accuracy of the evaluation. The actual power load characteristics at different times are incorporated into the formula, including the minimum node active power and the minimum node reactive power. These parameters can reflect the changes in power demand of the power grid in 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 to determine the access voltage of each node by continuously approaching the true value. This iterative method can gradually reduce the error and improve the accuracy of the calculation. At the same time, by setting preset iteration conditions to determine whether the iteration converges, the stability and reliability of the calculation process are ensured.

[0102] In a feasible implementation, in step 140 and step 150 in the above embodiment, the preset iteration condition is that the absolute value of the difference between the kth access voltage and the k+1th access voltage of each node at the tth moment is less than the iteration voltage difference threshold.

[0103] The iterative voltage difference threshold value may be obtained and set by an operator based on a large amount of experience, experiments or statistics.

[0104] In some embodiments, the present application preferably sets the iterative voltage difference threshold to 0.2.

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

[0106] It can be understood that by setting a clear iterative voltage difference threshold, it is possible to clearly define when the iteration process can be stopped, that is, when the change in the access voltage of all nodes in two consecutive iterations is less than the threshold, it is considered that the iteration is close enough to the true value and the iteration can be stopped. Such a setting makes the evaluation process more certain 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-precision evaluation is required, a smaller iterative voltage difference threshold can be selected to obtain a more accurate access voltage value, and when the accuracy requirements are not so strict, a slightly larger threshold can be selected to save computing time and resources. Furthermore, this setting also helps to improve the robustness and stability of the evaluation method, because in actual applications, the operating state of the power grid may be affected by a variety of factors and change, resulting in fluctuations in the calculation results of the access voltage. By setting the iterative voltage difference threshold, it can be ensured that even in this case, the evaluation method can stably converge to a reasonable solution, thereby avoiding misjudgment or misoperation due to unstable calculations.

[0107] In a feasible implementation, step 160 in the above embodiment determines the access evaluation result based on the target access voltage of all nodes at all times and the preset power supply voltage range, including: 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 the distributed photovoltaic at at least one node satisfies the preset access area as the access evaluation result; otherwise, the preset access capacity of the distributed photovoltaic at at least one node does not satisfy the preset access area as the access evaluation result.

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

[0109] In the embodiment of the present application, the access assessment result is determined by comparing the target access voltage with the preset power supply voltage range, which 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 power load characteristics, and has high flexibility and adaptability. This is of great significance for promoting the development of high-quality distribution networks and ensuring the safe and reliable operation of substation power grids. At the same time, the implementation of this step also provides a scientific basis for the optimal configuration of distributed photovoltaic systems, which helps to achieve the widespread application of clean energy and the green transformation of the energy structure.

[0110] It can be understood that by comparing the target access voltage of each node at each moment with the preset power supply voltage range, it is possible to accurately determine whether the access of distributed photovoltaics will affect the voltage stability of the power grid. If the target access voltage of all nodes is within the preset power supply voltage range, then the access capacity of distributed photovoltaics is reasonable and will not pose a threat to the safe operation of the power grid. On the contrary, if the target access voltage of a node exceeds the preset power supply voltage range, then it is necessary to re-evaluate the access capacity of distributed photovoltaics to ensure the safety and stability of the power grid. This evaluation method fully considers the actual operation of the power grid and the changes in the power load characteristics. By introducing the actual power load characteristics at different times, the evaluation method can more accurately reflect the voltage conditions of the power grid in different time periods, thereby avoiding misjudgment or missed judgment that may be caused by traditional methods. Furthermore, this evaluation method is also highly flexible and adaptable. The preset power supply voltage range can be adjusted according to actual needs to adapt to different evaluation accuracy and voltage stability requirements. At the same time, the evaluation method can also consider other factors affecting the voltage stability of the power grid, such as reactive power compensation, line loss, etc., to further improve the accuracy and reliability of the evaluation.

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

[0112] In some embodiments, the formula Determine the minimum node active power, minimum reactive power and maximum node voltage of each node at the tth moment; where R P,min,m,t is the minimum node active power of the mth node at the tth time, min() is the minimum value, R P,m,n,t is the active power of the mth node at the tth time on the nth day, N is the total number of days, R Q,min,m,t is the minimum node reactive power of the mth node at the tth moment, R Q,m,n,t is the node reactive power of the mth node at the tth moment on the nth day, R U,max,m,t is the maximum node voltage of the mth node at the tth moment, R U,m,n,t is the node voltage of the mth node at the tth moment on the nth day.

[0113] In an embodiment of the present application, by collecting and comparing the power parameters of each node at the t-th moment of multiple days, the minimum active power, minimum reactive power and maximum voltage of each node at that moment can be determined more accurately, which helps to more accurately evaluate the impact of distributed photovoltaic access on the substation power grid and ensure the accuracy of the evaluation results. In this way, all time points (t-th moment) are evaluated, so that the power load characteristics of different time periods can be analyzed, which enhances the flexibility of the evaluation method and enables it to adapt to changes in power demand in different regions and different time periods.

[0114] In a feasible implementation, the obtaining of the node active power, node reactive power and node voltage of each node in the preset area at the tth moment of each day in the above embodiment includes: obtaining the historical active power, historical reactive power and historical voltage of each user in the preset area at the tth moment of each day, and the topological wiring diagram of the preset area; performing data cleaning on the historical active power, historical reactive power and historical voltage of each user at the tth moment of each day to obtain the standard active power, standard reactive power and standard voltage of each user at the tth moment of each day; merging user nodes according to the topological wiring diagram to obtain multiple nodes; determining the node active power, node reactive power and node voltage of each node at the tth moment of each day according to the standard active power, standard reactive power and standard voltage of all users corresponding to each node at the tth moment of each day.

[0115] In the embodiment of the present application, through the above-mentioned processing steps, not only the data accuracy and evaluation efficiency are improved, but also the flexibility and adaptability of the evaluation method are enhanced, which provides a scientific basis for the optimal configuration of distributed photovoltaic systems, and helps to promote the development of high-quality distribution networks and the safe and reliable operation of substation power grids.

[0116] It can be understood that improving data accuracy: through the data cleaning step, outliers and duplicate values ​​are removed, ensuring the accuracy and reliability of subsequent analysis, which is crucial for evaluating the impact of distributed photovoltaic access on the substation power grid; simplifying the power grid model: through the node merging step, the power grid model is simplified, the amount of calculation is reduced, while maintaining the main characteristics of the power grid, which makes the evaluation process more efficient and ensures the accuracy of the evaluation results; adapting to different time periods: this implementation method takes into account the power parameters at the tth moment of each day, and can analyze the power load characteristics of different time periods, which enhances the flexibility of the evaluation method and enables it to adapt to changes in power demand in different regions and different time periods; providing a basis for accurate evaluation: by collecting and processing the power parameters of each node at the tth moment of multiple days, the minimum active power, minimum reactive power and maximum voltage of each node at that moment can be determined more accurately, which provides a solid foundation for the subsequent evaluation of the impact of distributed photovoltaic access on the substation power grid.

[0117] In a feasible implementation, the above embodiment determines the node active power, node reactive power and node voltage of each node at the tth moment of each day according to the standard active power, standard reactive power and standard voltage of all users corresponding to each node at the tth moment of each day, including:

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

[0119] Using the formula Determine the node voltage of each node at the tth moment of each day;

[0120] Among them, if r = P, then R r,m,n,t is the active power of the mth node at the tth moment on the nth day, R r ' ,i,n,t is the standard active power of the ith user at the tth time on the nth day. If r = Q, then R r,m,n,t is the node reactive power of the mth node at the tth moment on the nth day, R r ' ,i,n,t is the standard reactive power of the i-th user at the t-th moment on the n-th day, I m is the total number of users of the mth node, R U,m,n,t is the node voltage of the mth node at the tth time on the nth day, R′ U,i,n,t is the standard voltage of the i-th user at the t-th moment on the n-th day.

[0121] In the embodiments of the present application, rigorous formulas for the node active power, node reactive power and node voltage of each node at the t-th moment of each day are provided from a mathematical perspective. The accuracy of the calculated node active power, node reactive power and node voltage can be ensured from the rigor of mathematical logic, and the calculation formulas for the above-mentioned node active power, node reactive power and node voltage are preferably shown to provide reference, understanding and calculation for technical personnel.

[0122] In addition, by adopting the calculation formulas of node active power, node reactive power and node voltage preferably provided in the above-mentioned application, the node active power, node reactive power and node voltage of each node at the tth moment of each day can be accurately calculated, which can more accurately reflect the operating status of the substation power grid in different time periods. This helps to more accurately evaluate the impact of distributed photovoltaic access on the substation power grid and ensure the accuracy of the evaluation results.

[0123] In a feasible implementation, the historical active power, historical reactive power and historical voltage of each user at the t-th moment of each day in the above embodiment are cleaned to obtain the standard active power, standard reactive power and standard voltage of each user at the t-th moment of each day, including: determining the average active power, average reactive power and average voltage of each user at the t-th moment according to the historical active power, historical reactive power and historical voltage of each user at the t-th moment of all days; determining the active power variance, reactive power variance and voltage variance of each user at the t-th moment according to the average active power, average reactive power and average voltage of each user at the t-th moment, and the historical active power, historical reactive power and historical voltage of each user at the t-th moment of all days; for the historical active power, historical reactive power and historical voltage of each user at the t-th moment of each day, if the absolute value of the difference between the historical active power of the i-th user at the t-th moment of the n-th day and the average active power at the corresponding moment is greater than a preset multiple of the active power variance at the corresponding moment, then determining the i-th user as the i-th user. The historical active power of the i-th user at the t-th moment on the n-th day is an abnormal value, and the historical active power of the i-th user at the t-th moment on the n-th day is corrected to the average active power of the i-th user at the t-th moment; if the absolute value of the difference between the historical reactive power of the i-th user at the t-th moment on the n-th day and the average reactive power at the corresponding moment is greater than the preset multiple of the reactive power variance at the corresponding moment, then the historical reactive power of the i-th user at the t-th moment on the n-th day is determined to be an abnormal value, and the reactive power of the i-th user at the t-th moment on the n-th day is corrected to the average active power of the i-th user at the t-th moment on the n-th day. The power correction is the average reactive power of the ith user at the tth moment. If the absolute value of the difference between the historical voltage of the ith user at the tth moment on the nth day and the average voltage at the corresponding moment is greater than the preset multiple of the voltage variance at the corresponding moment, the historical voltage of the ith user at the tth moment on the nth day is determined to be an abnormal value, and the voltage of the ith user at the tth moment on the nth day is corrected to the average voltage of the ith user at the tth moment, so as to obtain the standard active power, standard reactive power and standard voltage of each user at the tth moment of each day.

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

[0125] In some embodiments, the present application preferably sets the preset multiple to 3.

[0126] In an embodiment of the present application, by performing data cleaning on the historical active power, historical reactive power and historical voltage of each user at the t-th moment of each day, a more accurate and stable data basis can be obtained, providing a strong guarantee for the subsequent distributed photovoltaic access capacity assessment, which 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 substation power grids.

[0127] It can be understood that improving data quality: by calculating the average active power, average reactive power and average voltage of each user at the tth moment, the typical power parameters of the user at all times can be obtained, providing a benchmark for subsequent analysis, and using variance to identify outliers, which can effectively eliminate abnormal data caused by equipment failure, data collection errors, etc., thereby improving data accuracy and reliability; enhancing data stability: the data cleaning process ensures the stability and consistency of the data in the time series by correcting the outliers to the average value, which is crucial for subsequent power flow analysis, voltage stability assessment, etc. A stable data foundation can make the assessment results more reliable and reduce the uncertainty caused by data fluctuations; optimizing analysis efficiency: the data cleaning process has a high degree of automation and can process large amounts of data in batches, thereby greatly improving analysis efficiency. Reducing the interference of abnormal data can make the subsequent iterative calculation process smoother and reduce computing time and resource consumption; improving evaluation accuracy: accurate data is the basis for evaluating distributed photovoltaic access capacity. Through data cleaning, it can ensure that the data input into the evaluation model is accurate and reliable, thereby improving the accuracy of the evaluation results. Accurate evaluation results can provide a scientific basis for the optimal configuration of distributed photovoltaic systems and ensure the safe and reliable operation of the power grid in the substation area; enhancing the adaptability of the evaluation method: the data cleaning process takes into account the fluctuations in power parameters of different users at the tth moment of the day, and identifies outliers through variance analysis, which enables the evaluation method to adapt to the power consumption characteristics and demand changes of different users. The adaptable evaluation method can better serve the power demand in different regions and different time periods, and provide strong support for the widespread application of distributed photovoltaic systems.

[0128] In a feasible implementation, the above embodiment determines the average active power, average reactive power and average voltage of each user at the tth moment according to the historical active power, historical reactive power and historical voltage of each user at the tth moment of all days, including:

[0129] Using the formula Determine the average active power, average reactive power and average voltage of each user at the tth moment;

[0130] In the above embodiment, the active power variance, reactive power variance and voltage variance of each user at the tth moment are determined according to the average active power, average reactive power and average voltage of each user at the tth moment, and the historical active power, historical reactive power and historical voltage of each user at the tth moment of all days, including:

[0131] Using the formula Determine the active power variance, reactive power variance and voltage variance of each user at the tth moment;

[0132] Among them, if r = P, then is the average active power of the i-th user at the t-th time, R r,i,n,t is the historical active power of the ith user at the tth moment on the nth day, δ r,i,t is the active power variance of the ith user at the tth moment. If r = Q, then is the average reactive power of the ith user at the tth moment, R r,i,n,t is the historical reactive power of the ith user at the tth moment on the nth day, δ r,i,t is the reactive power variance of the ith user at the tth moment. If r = U, then is the average voltage of the ith user at the tth moment, R r,i,n,t is the historical voltage of the ith user at the tth moment on the nth day, δ r,i,t is the voltage variance of the i-th user at the t-th moment, and N is the total number of days.

[0133] In the embodiments of the present application, rigorous formulas for the average active power, average reactive power and average voltage, as well as the active power variance, reactive power variance and voltage variance of each user at the tth moment are provided from a mathematical perspective. The accuracy of the calculated average active power, average reactive power and average voltage, as well as the active power variance, reactive power variance and voltage variance can be ensured from the rigor of mathematical logic. The calculation formulas for the above-mentioned average active power, average reactive power and average voltage, as well as the active power variance, reactive power variance and voltage variance are preferably shown to provide reference, understanding and calculation, etc. for technical personnel.

[0134] In addition, by adopting the above-mentioned preferred calculation formulas of the average active power, average reactive power and average voltage, as well as the active power variance, reactive power variance and voltage variance provided by the present application, the average active power, average reactive power and average voltage, as well as the active power variance, reactive power variance and voltage variance of each user at the tth moment can be accurately calculated, which can further improve the accuracy and reliability of the data, which helps to more accurately evaluate the impact of distributed photovoltaic access on the substation power grid and ensure the accuracy of the evaluation results.

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

[0136] See also Figure 2 , is a schematic diagram of a simplified substation network in an embodiment of the present application. The capacity of the substation transformer is 315kVA, the number of users is 73, overhead lines are used, and the conductor model is LGJ-50. The simplified substation network contains 18 nodes, and it is planned to connect distributed photovoltaics at nodes 5, 12 and 16.

[0137] On the premise that the access voltage of each node in the substation is maintained within the preset power supply voltage range, the evaluation method of the present application is used to calculate and determine the maximum photovoltaic capacity that can be accessed by these three nodes.

[0138] First, the power parameters of each node in the substation are collected at preset time intervals (15 minutes, i.e. 96 sampling points a day), including node active power, node reactive power and node voltage. Then, data cleaning is performed according to 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 obtained 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 substation 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 optimal configuration of distributed photovoltaic systems, but also effectively prevents the voltage over-limit problem caused by photovoltaic access, thereby ensuring the safe and reliable operation of the substation power grid.

[0140] It can be seen that the evaluation method of the present application can more accurately determine the upper limit of photovoltaic capacity suitable for access to each node in the substation by introducing the actual power load characteristics at different times and taking into account the complex network topology structure and line electrical parameter factors within the substation. The results of this specific implementation example of the present application also verify the effectiveness and accuracy of the present application.

[0141] In a second aspect, the present application provides a distributed photovoltaic access capacity assessment device.

[0142] See also Figure 3 , is a schematic diagram of a distributed photovoltaic access capacity assessment device in an embodiment of the present application, the device 310 includes:

[0143] The acquisition module 311 is used to obtain the preset access capacity of the distributed photovoltaic in the preset area at at least one node, the resistance value and the reactance value of each two adjacent nodes in the preset area, and the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth moment, 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 the tth moment according to the preset access capacity of at least one node, the resistance value and the reactance value of all two adjacent nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment, and use the access voltage as the first access voltage at the tth moment;

[0145] An iterative determination module 313 is used to determine the k+1th access voltage of each node at the tth time according to the kth access voltage of each node at the tth time, the minimum node active power and the minimum node reactive power, 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 for, when the absolute value of the difference between the kth access voltage and the k+1th access voltage of each node at the tth time satisfies the preset iteration condition, taking the k+1th access voltage as the target access voltage at the tth time, setting t=t+1, and returning to execute the step of obtaining the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth time, until t is equal to the total number of time;

[0147] The voltage iteration module 315 is used for, when the absolute value of the difference between the kth access voltage and the k+1th access voltage of at least one node at the tth time does not satisfy the preset iteration condition, setting k=k+1, and returning to the step of determining the k+1th access voltage of each node at the tth time according to the kth access voltage of each node at the tth time, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node;

[0148] The access assessment module 316 is used to determine an access assessment result according to the target access voltages of all nodes at all times and a preset power supply voltage range.

[0149] In the embodiment of the present application, the relevant contents of the acquisition module 311, the initial determination module 312, the iteration determination module 313, the time iteration module 314, the voltage iteration module 315 and the access evaluation module 316 can be referred to. Figure 1 The contents in the illustrated embodiment will not be described in detail here.

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

[0151] In an embodiment of the present application, the preset access capacity of distributed photovoltaics in at least one node in a preset area, the resistance value and reactance value of each two adjacent nodes in the preset area, and the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at the tth moment are first obtained, and then the target access voltage is determined through iterative calculation. 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 result; the device not only takes into account the complex network topology and line electrical parameter factors within the substation, but also introduces the actual power load characteristics at different times and performs a detailed analysis on them. It can more accurately determine the upper limit of photovoltaic capacity suitable for access to each node in the substation, provide a scientific basis for the optimal configuration of the distributed photovoltaic system, and effectively prevent the voltage over-limit problem caused by photovoltaic access, thereby ensuring the safe and reliable operation of the substation power grid. It 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 domestic distribution networks.

[0152] In a third aspect, the present application further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes a distributed photovoltaic access capacity assessment method in the above method embodiment.

[0153] In a fourth aspect, the present application further 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 executes a distributed photovoltaic access capacity assessment method in the above method embodiment.

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

[0155] The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor can implement each step in the above method embodiment. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor can implement each step in the above method embodiment. Those skilled in the art can understand that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0156] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing related hardware through a computer program. 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-mentioned methods.

[0157] Among them, any reference to memory, storage, database or other media used in the embodiments provided in the present 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. As an illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synch li nk) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0158] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A distributed photovoltaic access capacity assessment method, characterized in that: The method comprises: Obtaining the preset access capacity of distributed photovoltaics in at least one node in a preset area, and the resistance and reactance values ​​of each two adjacent nodes in the preset area, and obtaining the minimum node active power, minimum node reactive power and maximum node voltage of each node in the preset area at the tth moment, where t is a positive integer and the initial value of t is 1; Determine the access voltage of each node at the tth moment according to the preset access capacity of at least one node, the resistance value and the reactance value of all two adjacent nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment, and use the access voltage as the first access voltage at the tth moment; Determine the k+1th access voltage of each node at the tth moment according to the kth access voltage of each node at the tth moment, the minimum node active power and the minimum node reactive power, 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 the tth moment satisfies the preset iteration condition, the k+1th access voltage is used as the target access voltage at the tth moment, and t=t+1 is set, and the step of obtaining the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth moment is returned until t is equal to the total number of moments; When there is at least one node whose absolute value of the difference between the kth access voltage and the k+1th access voltage at the tth time 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 the tth time according to the kth access voltage of each node at the tth time, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node; The access assessment result is determined according to the target access voltage of all nodes at all times and the preset power supply voltage range.

2. The method according to claim 1, characterized in that The method of determining the access voltage of each node at the tth moment according to the preset access capacity of at least one node, the resistance value and the reactance value of all two adjacent nodes, and the minimum node active power, the minimum node reactive power and the maximum node voltage of all nodes at the tth moment comprises: Using the formula Determine the access voltage of each node at the tth moment; Among them, R U,m,t is the access voltage of the mth node at the tth moment, R U,0 is the voltage at the head end of the preset area, M is the total number of nodes, R P,min,y,t is the minimum node active power of the yth node at the tth moment, R P,pv,y is the preset access capacity of the yth node. If the yth node has no preset access capacity, then R P,pv,y =0, R y is the resistance between the yth node and the y-1th node, R Q,min,y,t is the minimum node reactive power of the yth node at the tth moment, X y is the reactance value between the yth node and the y-1th node, R U,max,x-1,t is the maximum node voltage of the x-1th node at the tth moment. If x=1, then R U,max,x-1,t =R U,0 .

3. The method according to claim 1, characterized in that The method of determining the k+1th access voltage of each node at the tth time according to the kth access voltage of each node at the tth time, the minimum node active power and the minimum node reactive power, and the preset access capacity of at least one node includes: Using the formula Determine the k+1th access voltage of each node at the tth time; in, is the k+1th access voltage of the mth node at the tth time, Y mm is the self-admittance between the mth node and the mth node, R P,min,m,t is the minimum node active power of the mth node at the tth moment, R P,pv,m is the preset access capacity of the mth node. If the mth node has no preset access capacity, then R P,pv,m =0, j is the imaginary unit of the complex number, R Q,min,m,t is the minimum node reactive power of the mth node at the tth moment, is the conjugate of the kth access voltage of the mth node at the tth time, M is the total number of nodes, if m = x, then Y mx is the self-admittance between the mth node and the xth node. If m≠x, then Y mx is the mutual admittance between the mth node and the xth node, is the kth access voltage of the xth node at the tth time.

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

5. The method according to claim 1, characterized in that The step of determining the access assessment result according to the target access voltages of all nodes at all times and the preset power supply voltage range includes: If the target access voltage of each node at each moment is within the preset power supply voltage range, the preset access capacity of the distributed photovoltaic at at least one node satisfies the access to the preset area as the access evaluation result; otherwise, the preset access capacity of the distributed photovoltaic at at least one node does not satisfy the access to the preset area as the access evaluation result.

6. The method according to claim 1, characterized in that The obtaining of the minimum node active power, the minimum node reactive power and the maximum node voltage of each node in the preset area at the tth moment includes: Obtaining the node active power, node reactive power and node voltage of each node in the preset area at the t-th moment of each day; Determine the minimum node active power of each node at the tth moment according to the node active power of each node at the tth moment of all days; Determine the minimum node reactive power of each node at the tth moment according to the node reactive power of each node at the tth moment of all days; The maximum node voltage of each node at the tth moment is determined according to the node voltage of each node at the tth moment of all days.

7. The method according to claim 6, characterized in that The obtaining of the node active power, node reactive power and node voltage of each node in the preset area at the t-th moment of each day includes: Obtaining the historical active power, historical reactive power and historical voltage of each user in the preset area at the t-th moment of each day, and the topological wiring diagram of the preset area; The historical active power, historical reactive power and historical voltage of each user at the t-th moment of each day are cleaned to obtain the standard active power, standard reactive power and standard voltage of each user at the t-th moment of each day; Merging user nodes according to the topology wiring diagram to obtain multiple nodes; The node active power, node reactive power and node voltage of each node at the tth moment of each day are determined according to the standard active power, standard reactive power and standard voltage of all users corresponding to each node at the tth moment of each day.

8. The method according to claim 7, characterized in that Determining the node active power, node reactive power and node voltage of each node at the tth moment of each day according to the standard active power, standard reactive power and standard voltage of all users corresponding to each node at the tth moment of each day includes: Using the formula Determine the node active power and node reactive power of each node at the tth moment of each day; Using the formula Determine the node voltage of each node at the tth moment of each day; Among them, if r = P, then R r,m,n,t is the active power of the mth node at the tth moment on the nth day, R r ' ,i,n,t is the standard active power of the ith user at the tth time on the nth day. If r = Q, then R r,m,n,t is the node reactive power of the mth node at the tth moment on the nth day, R r ' ,i,n,t is the standard reactive power of the i-th user at the t-th moment on the n-th day, I m is the total number of users of the mth node, R U,m,n,t is the node voltage of the mth node at the tth time on the nth day, R′ U,i,n,t is the standard voltage of the i-th user at the t-th moment on the n-th day.

9. The method according to claim 7, characterized in that: The data of the historical active power, historical reactive power and historical voltage of each user at the t-th moment of each day are cleaned to obtain the standard active power, standard reactive power and standard voltage of each user at the t-th moment of each day, including: Determine the average active power, average reactive power and average voltage of each user at the tth moment according to the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days; Determine the active power variance, reactive power variance and voltage variance of each user at the tth moment according to the average active power, average reactive power and average voltage of each user at the tth moment and the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days; For each user's historical active power, historical reactive power and historical voltage at the t-th moment of each day, if the absolute value of the difference between the historical active power of the ith user at the t-th moment of the n-th day and the average active power at the corresponding moment is greater than the preset multiple of the active power variance at the corresponding moment, the historical active power of the ith user at the t-th moment of the n-th day is determined to be an abnormal value, and the historical active power of the ith user at the t-th moment of the n-th day is corrected to the average active power of the ith user at the t-th moment. If the absolute value of the difference between the historical reactive power of the ith user at the t-th moment of the n-th day and the average reactive power at the corresponding moment is greater than the preset multiple of the reactive power variance at the corresponding moment, the historical active power of the ith user at the t-th moment of the n-th day is corrected to the average active power of the ith user at the t-th moment. If the historical reactive power of the i-th user at the t-th moment on the n-th day is an abnormal value, the reactive power of the i-th user at the t-th moment on the n-th day is corrected to the average reactive power of the i-th user at the t-th moment; if the absolute value of the difference between the historical voltage of the i-th user at the t-th moment on the n-th day and the average voltage at the corresponding moment is greater than the preset multiple of the voltage variance at the corresponding moment, the historical voltage of the i-th user at the t-th moment on the n-th day is determined to be an abnormal value, and the voltage of the i-th user at the t-th moment on the n-th day is corrected to the average voltage of the i-th user at the t-th moment, so as to obtain the standard active power, standard reactive power and standard voltage of each user at the t-th moment of each day.

10. The method according to claim 9, characterized in that Determining the average active power, average reactive power and average voltage of each user at the tth moment according to the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days includes: Using the formula Determine the average active power, average reactive power and average voltage of each user at the tth moment; Determining the active power variance, reactive power variance and voltage variance of each user at the tth moment according to the average active power, average reactive power and average voltage of each user at the tth moment, and the historical active power, historical reactive power and historical voltage of each user at the tth moment on all days, includes: Using the formula Determine the active power variance, reactive power variance and voltage variance of each user at the tth moment; Among them, if r = P, then is the average active power of the i-th user at the t-th time, R r,i,n,t is the historical active power of the ith user at the tth moment on the nth day, δ r,i,t is the active power variance of the ith user at the tth moment. If r = Q, then is the average reactive power of the ith user at the tth moment, R r,i,n,t is the historical reactive power of the ith user at the tth moment on the nth day, δ r,i,t is the reactive power variance of the ith user at the tth moment. If r = U, then is the average voltage of the ith user at the tth moment, R r,i,n,t is the historical voltage of the ith user at the tth moment on the nth day, δ r,i,t is the voltage variance of the i-th user at the t-th moment, and N is the total number of days.

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