Distributed photovoltaic maximum accessible capacity analysis method considering transformer area line loss

Abstract

The invention relates to a distributed photovoltaic maximum accessible capacity analysis method considering transformer area line loss. The distributed photovoltaic maximum accessible capacity analysis method comprises the following steps: data collection; the distributed photovoltaic installed capacity is calculated according to the roof area of the user; calculating the photovoltaic power generation power under the typical transformer area; theoretical line loss load flow calculation of the transformer area at each moment is carried out; judging whether the reverse supply power under the distributed photovoltaic installed capacity of the current transformer area is out of limit or not; theoretical line loss calculation of a target transformer area is carried out; theoretical line loss calculation of a target transformer area is carried out; and completing optimization of the jth lead in the target court, replacing the lead, and completing calculation of the optimal maximum photovoltaic access capacity of the court network frame. According to the method, the distributed photovoltaic accessible capacity is quantitatively analyzed from the three aspects of the reverse supply power index, the user voltage difference index and the wire load rate index, blindness of distributed photovoltaic access is avoided, and scientific guidance can be provided for reasonable access of the distributed photovoltaic.

Description

Technical Field

[0001] The present invention relates to the technical field of power grids, and in particular to a method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss in the substation area. Background Art

[0002] Nowadays, environmental protection and energy conservation issues have attracted wide attention. In this context, renewable energy has received increasing attention from all sectors of society due to its characteristics of being clean, low-carbon, and renewable. As the main form of renewable energy, the scale of distributed power sources connected to the power grid has been increasing significantly in recent years. However, its connection has also had a greater impact on the planning, reliability, relay protection, and power quality of the distribution network. At present, the selection of the access capacity and location of distributed photovoltaic mainly relies on manual experience.

[0003] When the power generation of distributed photovoltaic can be locally consumed, it can reduce the transmission distance and effectively reduce the operating cost of power grid enterprises; when the power generation of distributed photovoltaic cannot be locally consumed and is sent back to the superior power grid, it will increase the overall line loss of the distribution network and increase the operating cost of power grid enterprises. At present, each network province company lacks a systematic method to effectively guide the access of distributed photovoltaic capacity and location, which has a certain blindness and is likely to cause high line loss and power quality problems in the distribution network. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss in the substation area, so as to provide scientific guidance for the reasonable access of distributed photovoltaic.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss in the substation area includes the following steps:

[0007] Step 1, data collection: Collect the active power output, reactive power output, voltage, current data of all users at 96 points, the roof area of all users, and the substation area topology in a typical substation area;

[0008] Step 2, calculate the installed capacity of distributed photovoltaic according to the collected roof area of users;

[0009] Step 3, calculate the photovoltaic power generation under a typical substation area in combination with the installed capacity of the distributed photovoltaic;

[0010] Step 4, carry out the theoretical line loss power flow calculation at each moment in the substation area according to the photovoltaic power generation under the typical substation area, the active power output, reactive power output, voltage, current data of all users at 96 points, the roof area of all users, and the substation area topology data. The calculation process includes two parts: the conversion of main components and the power flow calculation;

[0011] Step 5: Based on the theoretical line loss calculation results at all calculation times in the area, determine whether the reverse supply power exceeds the limit under the current distributed photovoltaic installed capacity in the area;

[0012] Step 6: When the reverse supply power does not exceed the limit, directly jump to step 8: When the reverse supply power exceeds the limit, randomly convert the photovoltaic users whose total power generation power is equal to the reverse supply power exceeding the limit into ordinary users;

[0013] Step 7, repeat steps 4-6 until you can jump directly to step 8;

[0014] Step 8: Calculate the theoretical line loss in the target area, and analyze the user voltage difference based on the theoretical line loss calculation results at all calculation times in the area to determine whether there is a voltage over-limit situation.

[0015] Step 9: When there is no voltage over-limit user, directly jump to step 11; when there is a voltage over-limit user, convert the photovoltaic user with the largest voltage difference into a normal user;

[0016] Step 10, repeat steps 8-9 until you can jump to step 11;

[0017] Step 11, perform theoretical line loss calculation in the target area, and based on the theoretical line loss calculation results at all calculation times in the area, perform wire load rate analysis starting from the end wire to determine whether there is a current over-limit situation;

[0018] Step 12: when the value of the wire load rate is equal to 0, directly jump to step 14; when the wire load rate is equal to 1, convert the photovoltaic user whose current difference with the wire over-limit value downstream of wire j is closest to that of the photovoltaic user into a normal user;

[0019] Step 13, repeat steps 11-12 until you can jump to step 14;

[0020] Step 14, complete the optimization of the jth conductor in the target area, replace the conductor, repeat steps 11-14, until the optimization of all conductors in the target area is completed, and jump to step 15;

[0021] Step 15, complete the calculation of the maximum photovoltaic access capacity of the area grid optimization.

[0022] Furthermore, the distributed photovoltaic installed capacity is calculated based on the user's roof area. Assuming that the number of users of three phases A, B, and C in a typical area is N1, N2, and N3 respectively, and the roof area of ​​the first user of phase A is represented by SA1, the three-phase distributed photovoltaic installed capacity in the typical area is obtained as follows:

[0023]

[0024] In the above formula, DGRL A, DGRL B , DGRL C respectively represent the total installable capacity of three-phase distributed photovoltaic power generation for phases A, B, and C. S1 represents the area of a single photovoltaic panel, and P DG represents the capacity of a single photovoltaic panel.

[0025] Furthermore, in step 3, the specific calculation of the photovoltaic power generation for phases A, B, and C in a typical substation area is as follows:

[0026]

[0027] In the above formula, DGP A , DGP B , DGP C respectively represent the three-phase distributed photovoltaic power generation for phases A, B, and C; HA, ES, and K respectively represent the total solar irradiance on the horizontal plane, sunshine duration, and system comprehensive efficiency coefficient, and are all represented by the average value of historical data; respectively represent the total light-receiving area of the i-th user under phases A, B, and C in the typical substation area.

[0028] Furthermore, the main component conversion in step 4 includes:

[0029] ① Conversion of the outgoing line at the head end: The outgoing line at the head end of the distribution network is equivalent to a combined component composed of a virtual bus and a balanced node. At the same time, impedance equivalence, current injection, and power injection should be carried out, and the parameters of the converted component should be consistent with those of the component before conversion;

[0030] ② Conversion of ordinary users: They are directly equivalent to loads, and the parameters of the converted components should be consistent with those of the components before conversion;

[0031] ③ Conversion of distributed photovoltaic users: They are equivalent to a combined component composed of a virtual bus, a generator, and a load. It should be noted that before this step of conversion, it is necessary to judge whether its value is greater than 0. Only when it is greater than 0 is it necessary to perform virtual bus and generator conversion, otherwise only load conversion is required. In addition, the parameters of the components before and after conversion should also be consistent.

[0032] Furthermore, the power flow calculation in step 4 is specifically as follows:

[0033] Based on the calculation results of the three-phase photovoltaic power generation for phases A, B, and C in the typical substation area, combined with other operation data and the substation area topology, a power flow equation is established, and the Newton method is used to solve the power flow equation to obtain the calculation result of the line loss of the target typical substation area.

[0034] Furthermore, in step 5, based on the calculation results of the theoretical line loss at all calculation times in the substation area, it is judged whether the reverse power supply power is out of limit under the distributed photovoltaic installed capacity of the current substation area, specifically:

[0035]

[0036] In the above formula, FGPYX = 1 indicates that the reverse power supply exceeds the limit, FGPYX = 0 indicates that the reverse power supply does not exceed the limit, SYP represents the value of the active power at the head end of the target substation area, and TRL represents the substation area capacity;

[0037] The reverse power supply over-limit value is calculated by the following formula,

[0038] FGPYXZ = |SYP| - α * TRL (4)

[0039] Further, in step 8, the theoretical line loss of the target substation area is calculated. Based on the theoretical line loss calculation results at all calculation times in the substation area, the user voltage difference analysis is carried out to determine whether there is a voltage over-limit situation. Specifically,

[0040]

[0041] In the above formula, U Ai 、U Bi 、U Ci respectively represent the voltage values of the i-th user in the A, B, and C phases; when the values of FGUYX Ai 、FGUYX Bi 、FGUYX Ci are equal to 1, they respectively indicate that the i-th user in the A, B, and C phases is a voltage over-limit user, and when they are equal to 0, they respectively indicate that the i-th user in the A, B, and C phases has normal voltage.

[0042] Further, in step 11, the theoretical line loss of the target substation area is calculated. Based on the theoretical line loss calculation results at all calculation times in the substation area, the conductor load rate analysis is carried out starting from the end conductor to determine whether there is a current over-limit situation. Specifically,

[0043] Assume that there are N conductors in the target substation area. The current-carrying capacity of the j-th conductor in the substation area is represented by DXZI j , and the actual current is represented by DXSI j . The load rate analysis process of the j-th conductor is as follows:

[0044]

[0045] In the above formula, when the value of DXGZ j is equal to 1, it indicates that the j-th conductor is overloaded, and when it is equal to 0, it indicates that the j-th conductor is not overloaded.

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] 1. Using the reverse power supply index as the quantitative analysis basis for the maximum accessible capacity of distributed photovoltaics can avoid the overall line loss rate of the distribution network from being too high while ensuring power quality.

[0048] 2. Taking the user differential pressure index as the quantitative analysis basis for the maximum accessible capacity of distributed photovoltaic can avoid the overall line loss rate of the distribution network from being too high while ensuring power quality.

[0049] 3. Taking the conductor load rate index as the quantitative analysis basis for the maximum accessible capacity of distributed photovoltaic can avoid the overall line loss rate of the distribution network from being too high while ensuring power quality. For example, in the actual application in a certain area of Hubei Province, the situation of the conductor load rate exceeding the limit has been significantly reduced. Specifically, the average value of the conductor load rate limit has decreased from 77.86% before optimization to 30.43% after optimization, a decrease of 47.43%. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0051] Figure 1 is the method flowchart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0052] The technical solutions in the embodiments of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0053] The term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0054] The terms "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and cannot be construed as indicating or implying relative importance, nor can they be construed as requiring or implying any actual relationship or order between these entities or operations.

[0055] The present invention takes a typical distribution substation as the research object, and the overall flowchart is as Figure 1, first, collect the 96-point output data of all users in the target area and the photovoltaic access area of photovoltaic users; secondly, screen the users who can install photovoltaic panels according to the roof area of each user and simulate the installation of the maximum access photovoltaic capacity; thirdly, convert the photovoltaic users into virtual generators and carry out the theoretical line loss power flow calculation of the distribution substation area; at the same time, set the evaluation rules to carry out the reverse power supply analysis, user voltage difference analysis and three-phase balance analysis of distributed photovoltaic power generation in turn; finally, eliminate the photovoltaic power generation users that affect the power quality of the distribution substation area according to the analysis results, calculate and output the maximum photovoltaic access capacity and specific location of the target area, and guide the reasonable and orderly access of distributed photovoltaics.

[0056] As Figure 1 shown, the present invention provides a method for analyzing the maximum accessible capacity of distributed photovoltaics considering the line loss of the distribution substation area, and the specific implementation process is as follows:

[0057] Data collection: Collect the 96-point output data of all users in a typical distribution substation area (including voltage, active power, reactive power, etc. at specific times), photovoltaic power generation data of photovoltaic users, roof areas of all users and the topology of the distribution substation area.

[0058] According to the roof area of users, calculate the installed capacity of distributed photovoltaics. Assume that the number of users in phases A, B, and C in a typical distribution substation area are N1, N2, and N3 respectively, and the roof area of the first user in phase A is represented by SA1. The installed capacity of three-phase distributed photovoltaics in the typical distribution substation area is obtained as follows:

[0059]

[0060] In the above formula, DGRL A 、DGRL B 、DGRL C respectively represent the total installable capacity of distributed photovoltaics in phases A, B, and C, S1 represents the area of a single photovoltaic panel, and P DG represents the capacity of a single photovoltaic panel.

[0061] Calculate the photovoltaic power generation of phases A, B, and C in the typical distribution substation area.

[0062]

[0063] In the above formula, DGP A 、DGP B 、DGP C respectively represent the photovoltaic power generation of phases A, B, and C of distributed photovoltaics; HA, ES, and K respectively represent the total horizontal solar irradiance, sunshine duration, and system comprehensive efficiency coefficient, and are all represented by the average value of historical data; respectively represent the total light-receiving area of the i-th user in phases A, B, and C of the typical distribution substation area.

[0064] Conduct theoretical line loss power flow calculations for each moment in the substation area. The calculation process includes two parts: conversion of main components and power flow calculation.

[0065] (1) Conversion of main components

[0066] ① Conversion of the outgoing line at the head end: Equivalent the outgoing line at the head end of the distribution network to a combined component composed of a virtual bus and a balanced node. At the same time, impedance equivalence, current injection, and power injection should be carried out. The parameters of the converted component should be consistent with those of the component before conversion.

[0067] ② Conversion of ordinary users: Directly equivalent them to loads. The parameters of the converted component should be consistent with those of the component before conversion.

[0068] ③ Conversion of distributed photovoltaic users: Equivalent them to a combined component composed of a virtual bus, a generator, and a load. It should be noted that before this step of conversion, it is necessary to judge whether its value is greater than 0. Only when it is greater than 0, the conversion of the virtual bus and the generator is required, otherwise only the load conversion is required. In addition, the parameters of the component before and after conversion should also be consistent.

[0069] (2) Power flow calculation

[0070] Based on the calculation results of the photovoltaic power generation of phases A, B, and C in the typical substation area, combined with other operation data and the substation area topology, establish a power flow equation, and use the Newton method to solve the power flow equation to obtain the line loss calculation results of the target typical substation area.

[0071] Based on the theoretical line loss calculation results at all calculation moments in the substation area, judge whether the reverse power supply power exceeds the limit under the current distributed photovoltaic installed capacity in the substation area.

[0072]

[0073] In the above formula, FGPYX = 1 indicates that the reverse power supply power exceeds the limit, FGPYX = 0 indicates that the reverse power supply power does not exceed the limit, SYP represents the value of the active power at the head end of the target substation area, and TRL represents the substation area capacity.

[0074] When FGPYX = 0, directly jump to step 8. When FGPYX = 1, randomly convert the photovoltaic users whose sum of power generation is equal to the reverse power supply power limit value FGPYXZ into ordinary users (only using without generating). The reverse power supply power limit value is calculated by the following formula.

[0075] FGPYXZ = |SYP| - α * TRL (4)

[0076] Repeat steps 4 - 6 until it can be directly jumped to step 8.

[0077] Conduct theoretical line loss calculation for the target substation area. Based on the theoretical line loss calculation results at all calculation times in the substation area, conduct user voltage difference analysis to determine whether there is voltage over-limit.

[0078]

[0079] In the above formula, U Ai 、U Bi 、U Ci respectively represent the voltage values of the i-th user in phases A, B, and C; FGUYX Ai 、FGUYX Bi 、FGUYX Ci When the value is equal to 1, it respectively indicates that the i-th user in phases A, B, and C is a voltage over-limit user; when the value is equal to 0, it respectively indicates that the voltage of the i-th user in phases A, B, and C is normal.

[0080] When the values of FGUYX Ai 、FGUYX Bi 、FGUYX Ci are all equal to 0, it indicates that there is no voltage over-limit user, and directly jump to step 11; when there are values of FGUYX Ai 、FGUYX Bi 、FGUYX Ci equal to 1, it indicates that there is a voltage over-limit user, and convert the PV user with the largest voltage difference into a general user (only use without generating power).

[0081] 10. Repeat steps 8 - 9 until it is possible to jump to step 11.

[0082] 11. Conduct theoretical line loss calculation for the target substation area. Based on the theoretical line loss calculation results at all calculation times in the substation area, start conducting conductor load rate analysis from the end wire to determine whether there is current over-limit. Assume that there are N wires in the target substation area, and the current-carrying capacity of the j-th wire in the substation area is represented by DXZI j and the actual current is represented by DXSI j . The load rate analysis process of the j-th wire is as follows:

[0083]

[0084] In the above formula, when the value of DXGZ j is equal to 1, it indicates that the j-th wire is overloaded; when the value is equal to 0, it indicates that the j-th wire is not overloaded.

[0085] 12. When the value of DXGZ j is equal to 0, directly jump to step 14; when it is equal to 1, convert the PV user whose current difference from the wire over-limit value is the closest among the PV users downstream of wire j into a general user (only use without generating power)

[0086] 13. Repeat steps 11 - 12 until it is possible to jump to step 14.

[0087] 14. Complete the optimization of the j-th wire in the target distribution area, replace the wire, and repeat steps 11 - 14 until the optimization of all wires in the target distribution area is traversed, then jump to step 15.

[0088] 15. Complete the calculation of the maximum photovoltaic access capacity for the optimized distribution network structure of the distribution area.

[0089] In a method for analyzing the maximum accessible capacity of distributed photovoltaics considering line losses in a distribution area according to the present invention, using the reverse power supply index as the quantitative analysis basis for the maximum accessible capacity of distributed photovoltaics can avoid an excessive overall line loss rate of the distribution network while ensuring power quality. Using the user voltage difference index as the quantitative analysis basis for the maximum accessible capacity of distributed photovoltaics can avoid an excessive overall line loss rate of the distribution network while ensuring power quality. Using the wire load rate index as the quantitative analysis basis for the maximum accessible capacity of distributed photovoltaics can avoid an excessive overall line loss rate of the distribution network while ensuring power quality. For example, in the actual application in a certain area of Hubei Province, the situation of wire load rate exceeding the limit has been significantly reduced. Specifically, the average value of the wire load rate exceeding the limit has decreased from 77.86% before optimization to 30.43% after optimization, a decrease of 47.43%.

[0090] The above are only examples of the present invention and are not intended to limit the protection scope of the present invention. For those skilled in the art, various modifications and changes can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss of the transformer substation area, characterized in that It includes the following steps: Step 1, data collection: Collect the 96-point active power output, reactive power output, voltage, current data of all users in the typical substation area, the roof area of all users, and the substation area topology; Step 2, calculate the distributed photovoltaic installed capacity based on the collected roof area of users; Step 3, calculate the photovoltaic power generation under the typical substation area in combination with the distributed photovoltaic installed capacity; Step 4, based on the photovoltaic power generation under the typical substation area, the 96-point active power output, reactive power output, voltage, current data of all users, the roof area of all users, and the substation area topology data, carry out the theoretical line loss power flow calculation at each moment in the substation area. The calculation process includes two parts: main component conversion and power flow calculation; Step 5, based on the theoretical line loss calculation results at all calculation moments in the substation area, judge whether the reverse power supply power exceeds the limit under the current distributed photovoltaic installed capacity in the substation area; Step 6, when the reverse power supply power does not exceed the limit, directly jump to Step 8. When the reverse power supply power exceeds the limit, randomly convert photovoltaic users whose sum of power generation is equal to the reverse power supply power limit value into ordinary users; Step 7, repeat Steps 4-6 until it can be directly jumped to Step 8; Step 8, carry out the theoretical line loss calculation of the target substation area. Based on the theoretical line loss calculation results at all calculation moments in the substation area, carry out the user voltage difference analysis to judge whether there is a voltage over-limit situation; Step 9, when there is no voltage over-limit user, directly jump to Step 11; when there is a voltage over-limit user, convert the photovoltaic user with the largest voltage difference into an ordinary user; Step 10, repeat Steps 8-9 until it can be jumped to Step 11; Step 11, carry out the theoretical line loss calculation of the target substation area. Based on the theoretical line loss calculation results at all calculation moments in the substation area, start the conductor load rate analysis from the end conductor to judge whether there is a current over-limit situation; Step 12, when the value of the conductor load rate is equal to 0, directly jump to Step 14. When the conductor load rate is equal to 1, convert the photovoltaic user whose current difference from the conductor over-limit value is the closest among the photovoltaic users downstream of conductor j into an ordinary user; Step 13, repeat Steps 11-12 until it can be jumped to Step 14; Step 14, complete the optimization of the j-th conductor in the target substation area, replace the conductor, repeat Steps 11-14 until the optimization of all conductors in the target substation area is completed, and jump to Step 15; Step 15, complete the calculation of the maximum photovoltaic access capacity for the substation area grid optimization.

2. The method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss of the transformer area according to claim 1, wherein The specific calculation of the distributed photovoltaic installed capacity based on the roof area of users is as follows. Assume that the number of users in phases A, B, and C in the typical substation area are N1, N2, and N3 respectively, and the roof area of the first user in phase A is represented by SA1. The three-phase distributed photovoltaic installed capacity under the typical substation area is obtained as: In the above formula, DGRL A , DGRL B , DGRL C respectively represent the total installable capacity of distributed photovoltaics for three phases A, B, and C. S1 represents the area of a single photovoltaic panel, and P DG represents the capacity of a single photovoltaic panel.

3. The method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss of the substation area according to claim 2, wherein The specific calculation of the photovoltaic power generation in phases A, B, and C under the typical substation area in Step 3 is as follows, In the above formula, DGP A , DGP B , DGP C respectively represent the distributed photovoltaic power generation of three phases A, B, and C; HA, ES, and K respectively represent the total solar irradiance on the horizontal plane, sunshine duration, and system comprehensive efficiency coefficient, all represented by the average value of historical data; respectively represent the total light-receiving area of the i-th user under phases A, B, and C of the typical substation area.

4. The distributed photovoltaic maximum accessible capacity analysis method considering the line loss of the substation area according to claim 3, wherein, The main component conversion in Step 4 includes, ① Conversion of the outgoing line at the head end: Equivalent the outgoing line at the head end of the distribution network to a combined component composed of a virtual bus and a balanced node. At the same time, impedance equivalence, current injection, and power injection should be carried out. The parameters of the converted component should be consistent with those of the component before conversion; ② Conversion for ordinary users: directly equivalent to a load, and the parameters of the converted component should be the same as those of the component before conversion. ③ Conversion for distributed PV users: equivalent to a combined component composed of a virtual bus, a generator, and a load. It should be noted that before this step of conversion, it is necessary to judge whether its value is greater than 0. Only when it is greater than 0, the virtual bus and generator conversions are required; otherwise, only the load conversion is needed. In addition, the parameters of the component before and after conversion should also be the same.

5. The method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss in the substation area according to claim 3, wherein In step 4, the power flow calculation is specifically as follows: Based on the calculation results of the photovoltaic power generation of phases A, B, and C under a typical substation area, combined with other operation data and the substation area topology, a power flow equation is established, and the Newton method is used to solve the power flow equation to obtain the calculation result of the line loss of the target typical substation area.

6. The distributed photovoltaic maximum accessible capacity analysis method considering substation area line loss according to claim 3, characterized in that In step 5, based on the calculation results of the theoretical line loss at all calculation times in the substation area, it is judged whether the reverse power supply exceeds the limit under the installed capacity of distributed PV in the current substation area. Specifically: In the above formula, FGPYX = 1 indicates that the reverse power supply exceeds the limit, FGPYX = 0 indicates that the reverse power supply does not exceed the limit, SYP represents the value of the active power at the head end of the target substation area, and TRL represents the substation area capacity. The value of the reverse power supply limit is calculated by the following formula: FGPYXZ = |SYP| - α * TRL (4).

7. The method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss in the substation area according to claim 3, characterized in that, In step 8, the theoretical line loss of the target substation area is calculated. Based on the calculation results of the theoretical line loss at all calculation times in the substation area, the user voltage difference analysis is carried out to judge whether there is a voltage over-limit situation. Specifically: In the above formula, U Ai , U Bi , U Ci respectively represent the voltage values of the ith user in the three phases A, B, and C; FGUYX Ai and FGUYX Bi and FGUYX Ci When the values are equal to 1, they respectively indicate that the i-th user of the A, B, and C phases is a user with over-voltage limit, and when they are equal to 0, they respectively indicate that the voltage of the i-th user of the A, B, and C phases is normal.

8. The method for analyzing the maximum accessible capacity of distributed photovoltaic considering the line loss in the substation area according to claim 3, characterized in that In step 11, the theoretical line loss of the target substation area is calculated. Based on the calculation results of the theoretical line loss at all calculation times in the substation area, the conductor load rate analysis is carried out starting from the end conductor to judge whether there is a current over-limit situation. Specifically: Assume that there are N conductors in the target power distribution area, and the current-carrying capacity of the j-th conductor in the area is represented by DXZI j and the actual current is represented by DXSI j The load rate analysis process of the j-th conductor is as follows: In the above formula, DXGZ j having a value equal to 1 indicates that the j-th wire is overloaded, and having a value equal to 0 indicates that the j-th wire is not overloaded.

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