Method, apparatus and computer program product for determining number of low voltage users

Abstract

The application provides a low-voltage user quantity determination method, device and computer program product. The method comprises the following steps: acquiring a first user quantity at a first time; acquiring a power supply radius difference value; determining a second user quantity at a second time according to the power supply radius difference value; and calculating the sum of the first user quantity and the second user quantity to obtain a target user quantity. The scheme solves the problem that the low-voltage user quantity of multiple transformer areas in a region cannot be predicted in the prior art, and reference basis for early prediction of low-voltage conditions in a single transformer area or a region cannot be provided for a power supply enterprise.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution network analysis, in particular to a method and device for determining the number of low-voltage users, a computer program product and a user number determination system. BACKGROUND

[0002] In recent years, with the development of economy, the load of rural power grids has grown rapidly, and the demand for electricity of users has been increasing. However, the existing rural power grids have old lines, long power supply distance, and thin wire diameter, which results in insufficient terminal voltage and seriously affects the normal use of electricity by users in rural power grids. Power supply enterprises monitor the voltage data of terminal and user smart meters in each power consumption area through the system, statistically analyze the voltage fluctuation in a period of time, screen out the areas that meet the low-voltage determination standard, and then upgrade these low-voltage areas through relevant operation and maintenance methods or engineering projects, so as to solve the low-voltage problem.

[0003] The existing method can quickly determine whether the voltage value of a node in the low-voltage line network of the current area meets the low-voltage standard (less than 198V is low voltage), and can also use the method to analyze and predict the newly installed low-voltage users to determine whether low-voltage phenomenon will occur after the users are connected.

[0004] However, the method cannot predict the number of low-voltage users in multiple areas, and cannot provide a reference basis for power supply enterprises to predict low-voltage conditions in a single area or a region in advance. SUMMARY

[0005] The main purpose of the present application is to provide a method and device for determining the number of low-voltage users, a computer program product and a user number determination system, so as to at least solve the problem that the prior art cannot predict the number of low-voltage users in multiple areas, and cannot provide a reference basis for power supply enterprises to predict low-voltage conditions in a single area or a region in advance.

[0006] To achieve the above object, according to one aspect of the present application, a method for determining the number of users under low voltage is provided, comprising: obtaining a first number of users at a first time, wherein the first number of users is the number of user nodes with a voltage value less than or equal to a preset voltage value in a power supply area of a transformer at the first time; obtaining a power supply radius difference value, wherein the power supply radius difference value is the difference between a first maximum power supply radius of the transformer at the first time and a second maximum power supply radius of the transformer at a second time, the first time being earlier than the second time; determining a second number of users at the second time according to the power supply radius difference value, wherein the second number of users is the number of newly added user nodes with a voltage value less than or equal to the preset voltage value in the power supply area of the transformer at the second time, wherein the power supply radius difference value and the second number of users are in a positive correlation; and calculating the sum of the first number of users and the second number of users to obtain a target number of users.

[0007] Optionally, obtaining the power supply radius difference value comprises: obtaining a first current value, wherein the first current value is a phase current value of the transformer at the first time; determining the first maximum power supply radius according to the first current value, wherein the first maximum power supply radius is a power supply radius greater than the preset voltage value that can be provided by the transformer at the first time; determining a second current value according to the first current value, wherein the second current value is a phase current value of the transformer at the second time; determining the second maximum power supply radius according to the second current value, wherein the second maximum power supply radius is a power supply radius greater than the preset voltage value that can be provided by the transformer at the second time; and calculating the difference between the first maximum power supply radius and the second maximum power supply radius to obtain the power supply radius difference value.

[0008] Optionally, obtaining the first current value comprises: calculating the first current value according to a first formula, wherein the first formula is:

[0009]

[0010] I0 represents the first current value, R represents the resistance value of the transformer, η% represents the maximum load rate of the transformer at the first time, and n represents the number of outgoing line loops of the transformer at the first time.

[0011] Optionally, determining the first maximum power supply radius according to the first current value comprises: calculating the first maximum power supply radius according to a second formula, wherein the second formula is:

[0012]

[0013] L0 represents the first maximum power supply radius, U0 represents a single-phase voltage value of the transformer output, S represents a cross section of a wire transmitted by the transformer, and p represents an electrical resistivity of the wire transmitted by the transformer.

[0014] Optionally, determining the second current value according to the first current value comprises: calculating the second current value according to a third formula, wherein the third formula is:

[0015]

[0016] I X represents the second current value, a represents a load natural growth rate, dp i represents a connected load of the user node in a single phase, b i represents a coefficient of the connected load, represents a power factor of the connected load, sp i represents a connected load of the user node in three phases.

[0017] Optionally, determining the second maximum power supply radius according to the second current value comprises: calculating the second maximum power supply radius according to a fourth formula, wherein the fourth formula is:

[0018]

[0019] L x represents the second maximum power supply radius.

[0020] Optionally, determining the second user quantity at the second time according to the power supply radius difference value comprises: calculating the second user quantity according to a fifth formula, wherein the fifth formula is:

[0021]

[0022] D represents the second user quantity, W represents the first user quantity, L M represents a maximum power supply radius of the transformer at present, and AL represents the power supply radius difference value.

[0023] According to another aspect of the present application, a low-voltage user quantity determination device is provided, comprising: a first acquisition unit configured to acquire a first user quantity at a first time, wherein the first user quantity is the number of user nodes with a voltage value less than or equal to a preset voltage value in a power supply area of a transformer at the first time; a second acquisition unit configured to acquire a power supply radius difference value, wherein the power supply radius difference value is the difference between a first maximum power supply radius of the transformer at the first time and a second maximum power supply radius of the transformer at a second time, the first time being earlier than the second time; a determination unit configured to determine a second user quantity at the second time according to the power supply radius difference value, wherein the second user quantity is the number of newly added user nodes with a voltage value less than or equal to the preset voltage value in the power supply area of the transformer at the second time, and the power supply radius difference value and the second user quantity are in a positive correlation; and a calculation unit configured to calculate the sum of the first user quantity and the second user quantity to obtain a target user quantity.

[0024] According to still another aspect of the present application, a computer program product is provided, comprising a computer program configured to implement the steps of any of the low-voltage user quantity determination methods when executed by a processor.

[0025] According to yet another aspect of the present application, a user quantity determination system is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs comprise instructions for performing any of the low-voltage user quantity determination methods.

[0026] By applying the technical solution of the present application, the low-voltage user quantity can be determined through the power supply range of the transformer. With the application of the power grid, more and more devices are connected to the power grid, and a large amount of voltage is needed for power supply. With the increase of devices needing power supply, the maximum power supply radius of the transformer will decrease. With the decrease of the power supply radius, the voltage value obtained by the user nodes at the end of the power supply will become smaller and smaller, so that the user nodes at the end of the power supply become low-voltage user nodes (less than 198V are low-voltage user nodes). Therefore, the present solution can determine the number of low-voltage users in a single transformer area or a slice area through the change of the power supply radius of the transformer, thereby solving the problem that the prior art cannot provide reference for the power supply enterprise to predict the low-voltage situation in a single transformer area or a slice area in advance. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings constituting a part of the specification illustrate the present application, the exemplary embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 A hardware structure block diagram of a mobile terminal for performing a method for determining a number of users under low voltage is shown according to an embodiment of the present application;

[0029] Figure 2 A flowchart of a method for determining a number of users under low voltage is shown according to an embodiment of the present application;

[0030] Figure 3 A schematic diagram of a power supply radius contraction under normal voltage is shown;

[0031] Figure 4 A structure block diagram of a device for determining a number of users under low voltage is shown according to an embodiment of the present application.

[0032] Among the above drawings, the following reference signs are included:

[0033] 102, processor; 104, memory; 106, transmission device; 108, input / output device. DETAILED DESCRIPTION

[0034] It should be noted that the embodiments and features in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0035] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0037] In addition to monitoring by the system background, the judgment of the user side voltage can also be made by the line voltage loss table. As shown in Table 1, Table 1 shows the voltage drop of a single 70mm2 aluminum core overhead line. Given the wire diameter and node load of the user node front end conductor and the node location distance, the corresponding voltage drop value can be obtained by table lookup. Under the premise that the single-phase voltage at the output end of the transformer remains 220V, the voltage value of the user node can be obtained, so as to determine whether there is low voltage.

[0038] Table 1

[0039]

[0040] As introduced in the background, the prior art cannot predict the number of low-voltage users in multiple areas in the region, and cannot provide a reference basis for power supply enterprises to predict low-voltage conditions in a single area or a region in advance. To solve the above problems, the embodiments of the present application provide a method, device, computer program product and user number determination system for determining the number of low-voltage users.

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application.

[0042] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking the case of running on a mobile terminal, Figure 1 is a hardware structure block diagram of a mobile terminal of a low-voltage user number determination method according to an embodiment of the present application. As Figure 1 shown, the mobile terminal can include one or more Figure 1Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0043] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the device information display method in this embodiment of the invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory and non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the aforementioned networks may include wireless networks provided by the mobile terminal's communication provider. In one example, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0044] This embodiment provides a method for determining the number of users operating on a low-voltage mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0045] Figure 2 This is a flowchart illustrating a method for determining the number of low-voltage users according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0046] In step S201, a first user quantity at a first time is obtained, wherein the first user quantity is a quantity of user nodes with a voltage value less than or equal to a preset voltage value in a power supply area of a transformer at the first time;

[0047] Specifically, the transformer supplies power to the power supply area in the running process at the current first time, and the power supply area includes a plurality of user nodes, which can be powered. The user node is a user who needs to be powered and is the end of the power system, that is, the final destination of power transmission, and is usually a point connected to user equipment or load. At this node, the electric energy is converted into other forms of energy such as light energy and heat energy for use by users. However, some users are far away and get low voltage, and the preset voltage value is 198V. The user node with a voltage value less than 198V is a low voltage user node. Therefore, the first user quantity at the current first time can be obtained.

[0048] In step S202, a power supply radius difference value is obtained, wherein the power supply radius difference value is a difference between a first maximum power supply radius of the transformer at the first time and a second maximum power supply radius of the transformer at a second time, and the first time is earlier than the second time.

[0049] Specifically, as the number of power supply equipment increases, the maximum power supply radius of the transformer will decrease. As the power supply radius decreases, the voltage value obtained by the user node at the power supply end will become smaller and smaller, so that the user node at the power supply end becomes a low voltage user node (a user node with a voltage value less than 198V is a low voltage user node).

[0050] Specifically, the first maximum power supply radius of the transformer at the first time and the second maximum power supply radius of the transformer at the second time can be obtained. The difference between the two radii is calculated to obtain the reduced power supply area of the transformer, that is, the power supply radius difference value.

[0051] In step S203, the second user quantity at the second time is determined according to the power supply radius difference value, wherein the second user quantity is a quantity of newly added user nodes with a voltage value less than or equal to the preset voltage value in the power supply area of the transformer at the second time, and the power supply radius difference value and the second user quantity are in a positive correlation.

[0052] Specifically, as the voltage value obtained by the user node at the power supply end becomes smaller and smaller, the user node at the power supply end becomes a low voltage user node, and the user changes from a normal user to a low voltage user, that is, the second user quantity is obtained. The greater the power supply radius difference value, the more the second user quantity.

[0053] Step S204, calculate the sum of the first user number and the second user number to obtain the target user number.

[0054] Specifically, the original low-voltage first user number and the newly added low-voltage second user number are added to obtain the total number of low-voltage users at the second moment, that is, the target user number.

[0055] Through the embodiment, the number of low-voltage users can be determined by the power supply range of the transformer. As more and more devices are connected to the power grid, a large amount of voltage is needed to supply power. As the number of devices requiring power supply increases, the maximum power supply radius of the transformer will decrease. As the power supply radius decreases, the voltage value obtained by the user node at the end of the power supply will become smaller and smaller, so that the user node at the end of the power supply becomes a low-voltage user node (less than 198V is a low-voltage user node). Therefore, the present scheme can determine the number of low-voltage users in a single transformer area or a slice area by the change of the power supply radius of the transformer, thereby solving the problem that the prior art cannot provide reference for the power supply enterprise to predict the low-voltage situation in a single transformer area or a slice area in advance.

[0056] Specifically, low voltage in a transformer area is generally prone to concentrate at the end of the power supply range of the distribution transformer, so the calculation and analysis of the power supply boundary range of the transformer area can understand the number and distribution of low-voltage users to a certain extent. The definition of low-voltage transformer area for the power supply enterprise is that the low-voltage users contained therein exceed a certain number or proportion, and only the transformer area meeting the standard can be called a low-voltage transformer area, so that the power supply enterprise will invest in the project. The overall project fund is generally issued in advance to solve the problems of inventory and increment of low-voltage transformer areas. The inventory problem is that the low-voltage transformer area meeting the standard has been monitored, and the increment problem is that the low-voltage transformer area may appear this year. This number is generally estimated according to the experience of previous years, and there is no quantitative calculation and prediction, so scientific prediction of the number of low-voltage users and the number of low-voltage transformer areas has important reference significance for accurately grasping the increment of low-voltage transformer areas and issuing project investment amount with basis.

[0057] Specifically, the above scheme of the present application can quickly predict the number of low-voltage users in a single transformer area or a slice area, and can provide a basis for the power supply enterprise to list the key monitoring objects, thereby facilitating the power supply enterprise to intervene in advance and do the pre-work of low-voltage transformer area reconstruction.

[0058] Specifically, the scheme of the present application uses the following voltage drop formula to determine the transformer current in the prediction year, thereby calculating the power supply distance of the voltage from the transformer outlet end U0 to the low-voltage critical value 198V. As the prediction current increases, the power supply distance will decrease under the same voltage drop, so the users at the boundary will have low voltage.

[0059] In the implementation process, the power supply radius difference value can be obtained by the following steps: obtaining a first current value, wherein the first current value is the phase current value of the transformer at the first time; determining the first maximum power supply radius according to the first current value, wherein the first maximum power supply radius is the power supply radius greater than the preset voltage value that the transformer can provide at the first time; determining a second current value according to the first current value, wherein the second current value is the phase current value of the transformer at the second time; determining the second maximum power supply radius according to the second current value, wherein the second maximum power supply radius is the power supply radius greater than the preset voltage value that the transformer can provide at the second time; and calculating the difference between the first maximum power supply radius and the second maximum power supply radius to obtain the power supply radius difference value.

[0060] In this scheme, as the number of power supply devices increases, the maximum power supply radius of the transformer decreases. The power supply radius greater than the preset voltage value that the transformer can provide at the first time can be subtracted from the power supply radius greater than the preset voltage value that the transformer can provide at the second time, so as to obtain the difference between the two power supply radii, and then the number of newly added second users after the power supply is reduced can be further accurately determined.

[0061] Specifically, assuming that the single-phase voltage output from the secondary side of the transformer is U0, the single-phase user will have a voltage drop loss ΔU when the load current is transmitted in the loop formed by the live wire and the neutral wire, which can be calculated by the voltage drop formula: ΔU = 2*I*R (multiplied by 2 because each phase circuit is formed by the live wire and the neutral wire, so it is equivalent to 2 times the resistance from the power supply point to the power consumption point), according to the low voltage judgment standard, the single-phase voltage value lower than 198V belongs to low voltage, therefore the critical value of the voltage value obtained by the end single-phase user after the voltage drop loss should be 198V, at this time the voltage drop ΔU should be the maximum voltage drop that can be allowed, so the following relationship can be obtained: U0-ΔU = 198, ΔU = 2*I*R = U0-198, wherein R = ρ·L / S, substituting the above formula can obtain:

[0062] (is derived by substituting the resistance formula into the voltage drop formula, which is to indicate that the power supply distance L from the distribution transformer to the user end and which factors are related),

[0063] Wherein, L represents the length of the wire from the secondary side output end of the transformer to the user side, S represents the cross section of the wire, I represents the size of the wire transmission current, ρ represents the resistivity of the wire, and R represents the resistance of the wire.

[0064] Specifically, from the above derivation, it can be concluded that when the voltage of the secondary side output end of the transformer is fixed, the voltage on the user side is related to the power supply distance L, the cross section S of the wire, the size I of the current, and the resistivity p of the wire. When the voltage on the user side reaches the normal voltage minimum critical value 198V, if the cross section S of the wire, the size I of the current, and the resistivity p of the wire are known, L at this time is the maximum power supply radius that the current transformer can provide to meet the normal voltage, denoted as L0. That is, within the circular range with the transformer as the center and the radius L0, users can obtain normal voltage greater than 198V. If the low-voltage line current of the transformer increases to I X From the above formula, if the cross section S of the wire and the resistivity p remain unchanged (that is, the current transformer maintains the original state without modification), the maximum power supply radius that the transformer can provide to meet the normal voltage will decrease, denoted as L x . Therefore, the users distributed in L0-L X will change from normal voltage users to low voltage users. As shown in Figure 3 , the star represents the user node that is squeezed out of the normal voltage power supply radius, L1 represents the maximum power supply radius of the current normal voltage (which can also be L0, the first maximum power supply radius), and L X represents the maximum power supply radius of the normal voltage after x years (that is, the second maximum power supply radius).

[0065] In the specific implementation process, the first current value can be obtained by the following steps: calculating the first current value according to the first formula, wherein the first formula is:

[0066]

[0067] I0 represents the first current value, R represents the resistance value of the transformer, η% represents the maximum load rate of the transformer at the first time, and n represents the number of outgoing line loops of the transformer at the first time. The above formula is only exemplary, and any modification of the formula falls within the protection scope of the present application.

[0068] In the scheme, the first current value of each phase of the current transformer is I0. When the three-phase current of the transformer is balanced, the actual phase current of the transformer can be calculated from the resistance value (which can also be called capacity), the maximum load rate, and the number of low-voltage outgoing line loops to obtain the first current value. Through the scheme, a more accurate first current value can be obtained.

[0069] Specifically, in the above formula, the cross section S and resistivity p of the low-voltage line of the transformer area can be obtained from the basic data of the transformer area, the current of each phase of the transformer is set as I0, and the actual phase current of the transformer can be obtained by the transformer capacity (i.e. the resistance value R of the transformer), the load rate and the number of low-voltage outgoing lines when the three-phase current of the transformer is balanced, to obtain the first formula, wherein η% is the maximum load rate of the transformer in the current year in the normal operation mode, and n also represents the number of low-voltage outgoing lines.

[0070] Specifically, the rated current of the distribution transformer is obtained from the distribution transformer capacity and the line current formula

[0071] When the load rate of the distribution transformer is η% and the number of low-voltage outgoing lines is n, the line current of the distribution transformer is

[0072]

[0073]

[0074] In the specific implementation process, the first maximum power supply radius is determined according to the first current value, and the first maximum power supply radius can be realized by the following steps: the first maximum power supply radius is calculated according to the second formula, wherein the second formula is:

[0075]

[0076] L0 represents the first maximum power supply radius, U0 represents the single-phase voltage value output by the transformer, S represents the cross section of the conductor transmitted by the transformer, and p represents the resistivity of the conductor transmitted by the transformer. The formula is only exemplary, and any modification of the formula falls within the protection scope of the present application.

[0077] In the scheme, the first maximum power supply radius can be calculated by substituting the first current value into the second formula, i.e. the maximum radius of the current transformer that can be supplied with normal voltage, and the first maximum power supply radius can be obtained more accurately by the scheme.

[0078] In some embodiments, the second current value is determined according to the first current value, and the second current value can be realized by the following steps: the second current value is calculated according to the third formula, wherein the third formula is:

[0079]

[0080] I X represents the second current value, a represents the natural growth rate of the load, dp i represents the installed load of the single-phase user node, b i ​a coefficient representing the load of the installation, a power factor representing the load of the installation, sp i The above formula is only exemplary, and any formula modification falls within the protection scope of the present application.

[0081] In the scheme, the third formula defined in the present application can be used to predict the current value of each phase of the transformer in the xth planning year X The second current value is obtained, and the increased current includes the natural growth part and the newly installed load part, and the second current value can be obtained more accurately through the scheme.

[0082] Specifically, the above various parameters are explained as follows:

[0083] I X : the current of each phase of the transformer in the xth planning year, i.e. the second current value;

[0084] I0: the current of each phase of the transformer in the current, i.e. the first current value;

[0085] α: the natural growth rate of the load, which is determined according to the predicted regional load base and the economic development level, and is generally 2%-6%;

[0086] dp i : the installed single-phase load of the ith installation in the planning year from the current to the xth planning year (i=1, 2...N), which is assumed to be evenly connected to the three-phase conductors of each outgoing line of the transformer;

[0087] sp i : the installed three-phase load of the ith installation in the planning year from the current to the xth planning year (i=1, 2...N), which is assumed to be evenly connected to the three-phase conductors of each outgoing line of the transformer;

[0088] : the power factor of the ith installed user;

[0089] β i : the utilization coefficient of the ith installed user (i=1, 2...N), which is the stable load value divided by the installed capacity, and the utilization coefficient should be checked according to the load development of the same type of mature users in the region. The recommended values of the utilization coefficients of residential, commercial, industrial and other load types are 0.35, 0.4, 0.7 and 0.4 respectively.

[0090] Specifically, the first part of the third formula is the predicted current value after the natural growth of the load, I0 is the current, and a is the natural growth rate of the load of the transformer, so the load current of next year is I0*(1+a), and the load current of the following year is I0*(1+a) 2 , and so on, in the xth planning year, the load current of the transformer is I0*(1+a) X . The second part of the formula is to calculate the increased current of the newly installed single-phase user, and the installed capacity of each user is dp i , and the utilization coefficient is β i , so the actual capacity of each newly installed single-phase user is dp*β i , and then the single-phase user current is obtained from the single-phase capacity and voltage and current (U is 0.22V) Sum all the installed single-phase user currents, assuming they are evenly connected to the three-phase conductors of each outgoing line of the transformer, a total of 3*n outgoing lines, so the denominator is 3*n. The third part of the formula is to calculate the increased current of the newly installed three-phase user, and the basic idea is the same as calculating the single-phase user current in the second part. The difference is that the calculated current of the three-phase user is a three-phase current, and it is assumed to be evenly connected to n outgoing lines, so the denominator is n.

[0091] In some embodiments, the second maximum power supply radius is determined according to the second current value, and can be achieved by the following steps: calculating the second maximum power supply radius according to a fourth formula, wherein the fourth formula is:

[0092]

[0093] L x represents the second maximum power supply radius. The formula is only exemplary, and any modification of the formula falls within the scope of the present application.

[0094] In this scheme, by substituting the second current value into the fourth formula, the power supply radius L x of the normal voltage that the transformer can provide in the xth planning year can be predicted, that is, the second maximum power supply radius, and a more accurate second maximum power supply radius can be obtained by this scheme.

[0095] Specifically, according to the second formula and the fourth formula, in the xth planning year, the power supply radius of the normal voltage that the transformer can provide is reduced from L0 to L X , denoted as ΔL, and the users in ΔL will become low-voltage users.

[0096] In some embodiments, the second user quantity at the second time is determined according to the power supply radius difference, and specifically, the second user quantity can be determined by the following steps: the second user quantity is calculated according to a fifth formula, wherein the fifth formula is:

[0097]

[0098] D represents the second user quantity, W represents the first user quantity, L M represents the maximum power supply radius of the transformer, and AL represents the power supply radius difference. The formula is only exemplary, and any formula modification falls within the protection scope of the present application.

[0099] In the scheme, the second user quantity in the power supply radius difference can be roughly estimated according to the average distribution of the transformer position, and the number of newly added user nodes can be obtained through the fifth formula, thereby further solving the problem that the prior art cannot provide reference for the power supply enterprise to predict the low-voltage condition in a single area or a region in advance.

[0100] Specifically, since the number distribution of users from the transformer position is affected by multiple factors, such as the development of the village, the limitation of the land, the transformer distribution position, and the like, the user quantity distribution law of each area is different, and therefore the user quantity in AL can only be roughly estimated. Assuming that the users are averagely distributed from the transformer distribution position, assuming that the total low-voltage user quantity of the area is W, and the farthest power supply radius of the area is L M , then the user quantity per 1 meter of power supply distance is Therefore, the user quantity in AL can be roughly estimated, that is, the number of newly added low-voltage users D of the area is predicted in the xth planning year.

[0101] The second formula and the fourth formula are substituted into the fifth formula, and the following formula can be obtained:

[0102]

[0103] In the formula, the low-voltage user quantity of the area W, the farthest power supply radius of the area L M , the transformer output voltage U0, the low-voltage conductor cross section S, the low-voltage wire return number n, the transformer capacity R, the maximum load rate η%, the conductor resistivity p, the load natural growth rate α, the practical coefficient of the installed user β, and the power factor The newly installed single-phase load dp i and the three-phase load sp iThe number of predicted newly added low-voltage users D can be obtained from the basic data and installation work order statistics of the transformer area. When the number of D reaches a certain level, the power supply enterprise can list it as a low-voltage monitoring object and intervene in advance to prevent low-voltage phenomena in the later stage.

[0104] In addition, in the scheme of the present application, the degree of reduction of the transformer power supply radius needs to consider multiple factors, including the rated power of the transformer, the power supply line voltage, the power supply line current, the resistance and reactance of the power transmission line, the terrain and environment, etc. The reduction of the power supply radius can be evaluated by the following steps:

[0105] According to the rated power and rated voltage of the transformer. According to the load of the distribution line and the resistance loss of the power transmission line, the voltage drop is calculated: this needs to consider the resistance, reactance and current size of the line. Based on the rated capacity of the transformer and the calculated voltage drop, the farthest distance that the transformer can normally supply power under ideal conditions can be obtained;

[0106] When the voltage is high, the power supply radius can be increased accordingly; when the voltage is low, the power supply radius should be reduced. When the current is large, the power supply radius will decrease due to wire loss and voltage drop. The greater the resistance and reactance, the greater the power loss, and the power supply radius should be reduced accordingly. For example, in mountainous or marshy areas, due to complex environmental conditions, the power supply radius may be reduced. When the load rate is high, the impact of the distribution line increases, and the power supply radius may be reduced;

[0107] Suppose a transformer has a rated power of 100 kVA and a rated voltage of 400 V. Under ideal conditions (i.e. without considering other factors), its power supply radius may be initially determined to be 500 meters. If the actual power supply line voltage drops to 380 V, due to the decrease in voltage, the power supply radius may need to be reduced by 10%, i.e. to 450 meters. If the power supply line current is large, assuming it reaches 80% of the rated current, due to increased wire loss, the power supply radius may need to be reduced by another 5%, i.e. to 427.5 meters. If the transformer is located in a mountainous area, due to the complex terrain, the power supply radius may need to be reduced by another 5%, i.e. to 406 meters.

[0108] In addition, when the user load increases, resulting in insufficient transformer capacity, the transformer capacity should be increased. This needs to be evaluated and predicted based on user load. For example, the original transformer capacity is 500 kVA, and it is planned to upgrade to 800 kVA to meet the growing demand for user load. After upgrading, the transformer can carry a larger load without causing voltage drop.

[0109] In addition, when the transformer is powered at low voltage, if the power supply quality is poor, the load can be reasonably distributed to avoid overloading in some areas, leading to voltage drop. Real-time monitoring and adjustment of the load can be achieved through smart meters and monitoring systems. If the load continues to grow, consider upgrading the transformer capacity to meet demand. For example, upgrade a 500kVA transformer to 800kVA to handle larger loads.

[0110] In addition, the power supply radius definition refers to the distance from the transformer to the farthest power consumption device, which is related to the relationship between the rated voltage of the transformer and the rated power of the farthest power consumption device.

[0111] In summary, the present scheme reverses the application of the voltage drop formula, and derives the farthest power supply radius of the transformer to provide normal voltage according to the maximum allowed voltage drop. According to the difference in the maximum load current carried by the transformer in different periods, the difference of the farthest power supply radius is derived. The users within the difference are the users who are predicted to easily appear low voltage. The calculation of the predicted load current is more reasonable and accurate. The predicted load current is divided into a natural growth part and a newly installed part, and the newly installed part is further divided into single-phase installation current and three-phase installation current for calculation. Compared with the prior art, the present scheme can quickly predict the number and distribution of low-voltage users that may appear in the future in the transformer area. This method can not only predict a single transformer area, but also simultaneously predict and analyze multiple transformer areas within a region. Using this method, power supply enterprises can quantitatively analyze the possible low-voltage situation in the future in the region, advance the governance threshold of low voltage, and be prepared in advance.

[0112] The scheme of the present application has been applied to actual areas. The definition of low-voltage transformer area in X province is that when the number of low-voltage users carried by the transformer area exceeds 10 households or the proportion of low-voltage users carried by the transformer area in the total number of users carried by the transformer area is 20% or more, the transformer area is a low-voltage transformer area. Therefore, using the method of the present scheme to predict the number of low-voltage users in each transformer area, when the above judgment criteria are met, it is equivalent to predicting the number of low-voltage transformer areas.

[0113] Using the scheme of the present application to predict the number of low-voltage transformer areas in X province in 2022 and 2023 (that is, according to the transformer area basic data at that time and the installation work order in 22 and 23), it is calculated that 1879 new low-voltage transformer areas are predicted in 2022, and the actual number is 1823, with a deviation of 56, a deviation rate of 3.07%; it is calculated that 1413 new low-voltage transformer areas are predicted in 2023, and the actual number is 1348, with a deviation of 65, a deviation rate of 4.82%. Therefore, it is proved that this method is feasible.

[0114] The embodiment of the present application further provides a device for determining the number of users under low voltage. It should be noted that the device for determining the number of users under low voltage can be used to execute the method for determining the number of users under low voltage. The device is used to realize the above-mentioned embodiment and preferred embodiment, and the description is not repeated. As used below, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the device described in the following embodiment is preferably realized in software, the realization of hardware or a combination of software and hardware is also possible and is conceived.

[0115] The device for determining the number of users under low voltage provided by the embodiment of the present application is introduced below.

[0116] Figure 4 Fig. 1 is a structural block diagram of a device for determining the number of users under low voltage according to the embodiment of the present application. As shown in Fig. 1, the device comprises: Figure 4

[0117] The first acquisition unit 10 is configured to acquire a first number of users at a first time point, wherein the first number of users is the number of user nodes with a voltage value less than or equal to a preset voltage value in a power supply area of a transformer at the first time point.

[0118] The second acquisition unit 20 is configured to acquire a power supply radius difference value, wherein the power supply radius difference value is the difference between a first maximum power supply radius of the transformer at the first time point and a second maximum power supply radius of the transformer at a second time point, and the first time point is earlier than the second time point.

[0119] The determination unit 30 is configured to determine a second number of users at the second time point according to the power supply radius difference value, wherein the second number of users is the number of newly added user nodes with a voltage value less than or equal to the preset voltage value in the power supply area of the transformer at the second time point, and the power supply radius difference value and the second number of users are in a positive correlation.

[0120] The calculation unit 40 is configured to calculate the sum of the first number of users and the second number of users to obtain a target number of users.

[0121] ​Through the embodiment, the number of low-voltage users can be determined through the power supply range of the transformer. As the power grid is applied, more and more devices are added to the power grid, and a large amount of voltage is required for power supply. As the number of devices requiring power supply increases, the maximum power supply radius of the transformer will also decrease. As the power supply radius decreases, the voltage value obtained by the user node at the end of the power supply will become smaller and smaller, so that the user node at the end of the power supply becomes a low-voltage user node (less than 198V is a low-voltage user node). Therefore, the number of low-voltage users in a single transformer area or a slice area can be determined through the change of the power supply radius of the transformer, thereby solving the problem that the prior art cannot provide reference for the power supply enterprise to predict the low-voltage situation in a single transformer area or a slice area in advance.

[0122] In the specific implementation process, the second acquisition unit includes an acquisition module, a first determination module, a second determination module, a third determination module, and a first calculation module. The acquisition module is configured to acquire a first current value, wherein the first current value is a phase current value of the transformer at the first time point. The first determination module is configured to determine the first maximum power supply radius according to the first current value, wherein the first maximum power supply radius is a power supply radius greater than the preset voltage value that can be provided by the transformer at the first time point. The second determination module is configured to determine a second current value according to the first current value, wherein the second current value is a phase current value of the transformer at the second time point. The third determination module is configured to determine the second maximum power supply radius according to the second current value, wherein the second maximum power supply radius is a power supply radius greater than the preset voltage value that can be provided by the transformer at the second time point. The first calculation module is configured to calculate the difference between the first maximum power supply radius and the second maximum power supply radius to obtain the power supply radius difference.

[0123] In the scheme, as the number of devices requiring power supply increases, the maximum power supply radius of the transformer will also decrease. The power supply radius greater than the preset voltage value that can be provided by the transformer at the first time point can be subtracted from the power supply radius greater than the preset voltage value that can be provided by the transformer at the second time point. The difference between the two power supply radii can be obtained, and the number of newly added second users after the power supply is reduced can be further accurately determined subsequently.

[0124] In the specific implementation process, the acquisition module includes a first calculation submodule, and the first calculation submodule is configured to calculate the first current value according to a first formula, wherein the first formula is:

[0125]

[0126] I0 represents the first current value, R represents the resistance value of the transformer, η% represents the maximum load rate of the transformer at the first moment, and n represents the number of outgoing circuit loops of the transformer at the first moment. The above formula is only exemplary, and any modification of the formula falls within the protection scope of the present application.

[0127] In the scheme, the first current value of each phase of the current transformer is I0, and when the three-phase current of the transformer is balanced, the actual phase current of the transformer can be calculated from the first current value of the resistance value (which can also be called the capacity), the maximum load rate, and the number of low-voltage outgoing circuit loops. Through the scheme, a more accurate first current value can be obtained.

[0128] In the specific implementation process, the first determination module includes a second calculation submodule, and the second calculation submodule is configured to calculate the first maximum power supply radius according to a second formula, wherein the second formula is:

[0129]

[0130] L0 represents the first maximum power supply radius, U0 represents the single-phase voltage value output by the transformer, S represents the cross section of the conductor transmitted by the transformer, and p represents the resistivity of the conductor transmitted by the transformer. The above formula is only exemplary, and any modification of the formula falls within the protection scope of the present application.

[0131] In the scheme, the first maximum power supply radius can be calculated by substituting the first current value into the second formula, that is, the maximum radius of the current transformer that can be supplied with normal voltage. Through the scheme, a more accurate first maximum power supply radius can be obtained.

[0132] In some embodiments, the second determination module includes a third calculation submodule, and the third calculation submodule is configured to calculate the second current value according to a third formula, wherein the third formula is:

[0133]

[0134] I X represents the second current value, a represents the natural growth rate of the load, dp i represents the installed load of the single-phase user node, b i represents the coefficient of the installed load, represents the power factor of the installed load, sp i represents the installed load of the three-phase user node. The above formula is only exemplary, and any modification of the formula falls within the protection scope of the present application.

[0135] In the scheme, the third formula defined in the present application can predict the current value IX The second current value is the current value of the transformer, and the increased current includes a natural growth part and a load part of the newly packaged part, and the second current value can be obtained more accurately through the scheme.

[0136] In some embodiments, the third determining module includes a fourth calculating sub-module configured to calculate the second maximum power supply radius according to a fourth formula.

[0137]

[0138] L x The second maximum power supply radius is represented by L. The formula is only exemplary, and any formula variation falls within the protection scope of the present application.

[0139] In the scheme, the second current value is substituted into the fourth formula to predict the power supply radius L of the normal voltage provided by the transformer in the xth planning year. x The second maximum power supply radius is represented by L. The second maximum power supply radius can be obtained more accurately through the scheme.

[0140] In some embodiments, the determining unit includes a second calculating module configured to calculate the second user quantity according to a fifth formula.

[0141]

[0142] D represents the second user quantity, W represents the first user quantity, and L M L represents the maximum power supply radius of the transformer, and AL represents the power supply radius difference. The formula is only exemplary, and any formula variation falls within the protection scope of the present application.

[0143] In the scheme, the second user quantity in the power supply radius difference can be roughly estimated according to the average distribution of the transformer positions, the number of newly added user nodes can be obtained through the fifth formula, and the problem that the low-voltage condition in a single area or region cannot be predicted in advance to provide a reference for the power supply enterprise in the prior art is further solved.

[0144] The low-voltage user quantity determining device includes a processor and a memory. The first obtaining unit, the second obtaining unit, the determining unit, and the calculating unit are all stored in the memory as program units, and the processor executes the program units stored in the memory to realize the corresponding functions. The modules are located in the same processor, or the modules are located in different processors in any combination.

[0145] The processor comprises a core, and the core retrieves corresponding program units in the memory. The core can be provided with one or more than one, and the number of low-voltage users in a region can be predicted by adjusting the core parameters.

[0146] The memory can include non-permanent memory in a computer readable medium, random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one memory chip.

[0147] The embodiment of the present application provides a computer readable storage medium, and the computer readable storage medium comprises a stored program, wherein the program controls a device where the computer readable storage medium is located to execute the determination method of the number of low-voltage users when the program runs.

[0148] The embodiment of the present application provides a processor, and the processor is used for running a program, wherein the program executes the determination method of the number of low-voltage users when the program runs.

[0149] The embodiment of the present application provides a device, and the device comprises a processor, a memory, and a program stored in the memory and capable of running on the processor, and the processor executes the program to realize at least the determination method of the number of low-voltage users.

[0150] The device in the present application can be a server, a PC, a PAD, a mobile phone, and the like.

[0151] A computer program product comprises a non-volatile computer readable storage medium, the non-volatile computer readable storage medium stores a computer program, and the computer program is executed by a processor to realize the steps of the determination method of the number of low-voltage users in the embodiments of the present application.

[0152] The present application further provides a user number determination system, comprising one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs comprise a determination method of the number of low-voltage users.

[0153] It should be apparent to those skilled in the art that the modules or steps of the application described above can be implemented with a general purpose computer, and can be centralized in a single computer or distributed among a network of computers, and can be implemented with program code executable by a computer, and thus can be stored in a storage device and executed by a computer, and in some cases, the steps shown or described can be executed in a different order than shown or described, or can be implemented as separate integrated circuit modules or as a single integrated circuit module, and thus the application is not limited to any particular combination of hardware and software.

[0154] Those skilled in the art will appreciate that embodiments of the application can be devised for a method, a system, or a computer program product. Accordingly, the application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the application can be embodied in the form of a computer program product on one or more computer readable storage media (including, but not limited to, disk memory, CD-ROMs, optical storage media, etc.) having computer usable program code embodied thereon.

[0155] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above.

[0156] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above.

[0157] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts described above.Figure 1 one or more processes and / or functions specified in one or more blocks Figure 1 one or more processes and / or functions specified in one or more blocks

[0158] In one typical arrangement, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0159] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, non-volatile memory, such as read-only memory (ROM), EPROM, and / or flash memory, etc. The memory is an example of computer readable media.

[0160] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassette, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer readable media does not include transitory media, such as modulated data signals and carrier waves.

[0161] It should also be noted that the terms "comprising", "containing", or any other variant thereof, are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element.

[0162] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0163] 1) The method for determining the number of low-voltage users in this application can be based on the power supply range of the transformer. With the application of the power grid, more and more equipment is being added to the grid, requiring a large amount of voltage for power supply. As the number of equipment requiring power supply increases, the maximum power supply radius of the transformer will also decrease. As the power supply radius decreases, the voltage value obtained by the user node at the end of the power supply will become smaller and smaller, making the user node at the end of the power supply a low-voltage user node (any voltage less than 198V is considered a low-voltage user node). Therefore, this solution can determine the number of low-voltage users in a single transformer area or region by changing the power supply radius of the transformer, thereby solving the problem in the prior art that it is impossible to provide a reference for power supply companies to predict the low-voltage situation in a single transformer area or region in advance.

[0164] 2) The device for determining the number of low-voltage users in this application can determine the number of low-voltage users by the power supply range of the transformer. With the application of the power grid, more and more equipment is added to the power grid, requiring a large amount of voltage to supply power. As the number of equipment requiring power supply increases, the maximum power supply radius of the transformer will also decrease. As the power supply radius decreases, the voltage value obtained by the user node at the end of the power supply will become smaller and smaller, making the user node at the end of the power supply a low-voltage user node (less than 198V is considered a low-voltage user node). Therefore, this solution can determine the number of low-voltage users in a single transformer area or region by changing the power supply radius of the transformer, thereby solving the problem in the prior art that it is impossible to provide a reference for power supply companies to predict the low-voltage situation in a single transformer area or region in advance.

[0165] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of determining a number of users at a low voltage, characterized by, The method comprises the following steps: obtaining a first user quantity at a first time, wherein the first user quantity is the number of user nodes with a voltage value less than or equal to a preset voltage value in a power supply area of a transformer at the first time; obtaining a power supply radius difference value, wherein the power supply radius difference value is the difference between a first maximum power supply radius of the transformer at the first time and a second maximum power supply radius of the transformer at a second time, the first time being earlier than the second time; determining a second user quantity at the second time according to the power supply radius difference value, wherein the second user quantity is the number of newly added user nodes with a voltage value less than or equal to the preset voltage value in the power supply area of the transformer at the second time, and the power supply radius difference value and the second user quantity are in a positive correlation relationship; calculating the sum of the first user quantity and the second user quantity to obtain a target user quantity.

2. The method of claim 1, wherein, The method for obtaining the power supply radius difference value comprises the following steps: obtaining a first current value, wherein the first current value is a phase current value of the transformer at the first time; determining the first maximum power supply radius according to the first current value, wherein the first maximum power supply radius is a power supply radius greater than the preset voltage value that can be provided by the transformer at the first time; determining a second current value according to the first current value, wherein the second current value is a phase current value of the transformer at the second time; determining the second maximum power supply radius according to the second current value, wherein the second maximum power supply radius is a power supply radius greater than the preset voltage value that can be provided by the transformer at the second time; calculating the difference between the first maximum power supply radius and the second maximum power supply radius to obtain the power supply radius difference value.

3. The method of claim 2, wherein, The method for obtaining the first current value comprises the following steps: calculating the first current value according to a first formula, wherein the first formula is: ， represents the first current value, represents a resistance value of the transformer, represents a maximum load rate of the transformer at a first time, represents a number of outgoing line circuits of the transformer at a first time.

4. The method of claim 3, wherein, The method for determining the first maximum power supply radius according to the first current value comprises the following steps: calculating the first maximum power supply radius according to a second formula, wherein the second formula is: ， denotes the first maximum power supply radius, denotes the single-phase voltage value of the transformer output, denotes the cross section of the conductor transmitted by the transformer, denotes the resistivity of the conductor transmitted by the transformer.

5. The method of claim 4, wherein, The method for determining the second current value according to the first current value comprises the following steps: calculating the second current value according to a third formula, wherein the third formula is: ， represents the second current value, represents the natural growth rate of the load, represents the installed load of the user node in single phase, represents the coefficient of the installed load, represents the power factor of the installed load, represents the installed load of the user node in three phase.

6. The method of claim 5, wherein, The method for determining the second maximum power supply radius according to the second current value comprises the following steps: calculating the second maximum power supply radius according to a fourth formula, wherein the fourth formula is: ， represents the second maximum power supply radius.

7. The method of claim 2, wherein, The method for determining the second user quantity at the second time according to the power supply radius difference value comprises the following steps: calculating the second user quantity according to a fifth formula, wherein the fifth formula is: ， representing the second number of users, representing the first number of users, representing the maximum power supply radius of the transformer at present, representing the power supply radius difference value.

8. A low voltage subscriber number determination apparatus, characterized by The method comprises the following steps: a first obtaining unit is configured to obtain a first user quantity at a first time, wherein the first user quantity is the number of user nodes with a voltage value less than or equal to a preset voltage value in a power supply area of a transformer at the first time; a second obtaining unit is configured to obtain a power supply radius difference value, wherein the power supply radius difference value is the difference between a first maximum power supply radius of the transformer at the first time and a second maximum power supply radius of the transformer at a second time, the first time being earlier than the second time; A determining unit is configured to determine a second user quantity at the second time according to the power supply radius difference, wherein the second user quantity is a quantity of newly added user nodes with a voltage value less than or equal to the preset voltage value in the power supply area of the transformer at the second time, and the power supply radius difference and the second user quantity are in a positive correlation. A calculating unit is configured to calculate a sum of the first user quantity and the second user quantity to obtain a target user quantity.

9. A computer program product comprising a computer program, characterized in that, The computer program, when executed by a processor, implements the steps of the method for determining the low-voltage user quantity according to any one of claims 1 to 7.

10. A user number determination system, characterized by The computer program product comprises: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs comprise a program for executing the method for determining the low-voltage user quantity according to any one of claims 1 to 7.

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