Evaluation method for distributed photovoltaic bearing capacity problem of current distribution network

Abstract

The invention discloses a method for evaluating the distributed photovoltaic bearing capacity problem of a current distribution network, and belongs to the technical field of power systems. Firstly, residents and industrial and commercial users are distinguished, photovoltaic development potentials of various users are calculated based on roof areas, and the industrial and commercial potentials are further subdivided into low-voltage and medium-voltage levels; secondly, in combination with user distribution, distributing potentials to power distribution and medium-voltage lines step by step, and calculating residual photovoltaic development potentials around the power distribution and medium-voltage lines; then, comprehensively considering the actual photovoltaic power generation efficiency, the midday minimum load and the equipment reverse transmission load rate limitation, and calculating the residual distributed photovoltaic accessible capacity of the distribution transformer and the medium-voltage line; and finally, comparing the residual accessible capacity with the residual development potential step by step, and accurately identifying specific equipment with the problem of insufficient bearing capacity or reverse conveying overload. According to the method, the defects that an existing region evaluation method is rough and equipment-level simulation evaluation is tedious are overcome, and an effective basis is provided for accurate planning and transformation of the power distribution network.

Description

Technical Field

[0001] This invention belongs to the field of power systems, specifically relating to a method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks. Background Technology

[0002] With the rapid development of the distributed photovoltaic (PV) industry, the installed capacity of distributed PV will continue to grow significantly in the future. The large-scale integration of distributed PV power generation equipment has a substantial impact on the operation of the power distribution network. During peak PV power generation periods, traditional electricity consumers may become power generators, changing the energy flow from unidirectional to bidirectional. Furthermore, due to the uneven distribution of power distribution network resources, electricity demand, and PV potential in some areas, localized power distribution equipment may face the risk of backfeeding overload during peak PV power generation periods, affecting the operational safety of the power distribution network. Currently, the mainstream assessment methods mainly fall into two categories:

[0003] 1. Regional Macro-Assessment Method Based on Power Supply Grid: This method typically estimates the bearing capacity based on the total substation capacity, average load, and total roof area of ​​a region (such as the entire power supply grid or county). However, this method has an inherent flaw:

[0004] Neglecting grid structure: The capacity limitations and uneven distribution of specific equipment such as distribution transformers and medium-voltage lines in the distribution network were not taken into account.

[0005] User type confusion: Residential and industrial / commercial users are lumped together, ignoring the significant differences between the two in terms of electricity regulations, user load characteristics, and photovoltaic development ratios, leading to distorted potential assessments.

[0006] The conclusion is not instructive: its assessment results cannot accurately pinpoint which specific transformer or line has a capacity bottleneck, and therefore cannot provide a direct and effective basis for precise investment and renovation of the power distribution network.

[0007] 2. Equipment-level evaluation method based on detailed modeling and simulation: This method establishes an accurate electrical model for specific power distribution equipment and calculates its connectable capacity through simulation. Although this method has high accuracy, it has significant limitations in application:

[0008] The data requirements are stringent: it requires the collection of complete network topology, line parameters, real-time load data, etc., which makes large-scale assessments costly and difficult to implement.

[0009] Low computational efficiency: The simulation process is complex and time-consuming, making it unsuitable for scenarios that require rapid screening of hundreds or thousands of distribution transformers and lines.

[0010] Lack of universality: Its strong model dependence makes it difficult to form a standardized, scalable, and rapid evaluation system.

[0011] Therefore, there is an urgent need in this field for an assessment method that can achieve a good balance between assessment accuracy and implementation efficiency, which can overcome the roughness of macro-assessment and avoid the cumbersomeness of detailed simulation, thereby enabling rapid and accurate positioning of distributed photovoltaic carrying capacity issues in distribution networks. Summary of the Invention

[0012] To promptly identify distribution network carrying capacity issues during the development of distributed photovoltaic (PV) power and facilitate advance planning for the construction and renovation of the distribution network, this invention proposes a method for assessing the carrying capacity of distributed PV power in the current distribution network.

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] In a first aspect, the present invention provides a method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks, comprising the following steps:

[0015] Step 1: Differentiate between residential and industrial / commercial users, collect the roof area of ​​each power grid in the area to be evaluated, and calculate the photovoltaic development potential for residential and industrial / commercial users; combine the current photovoltaic installation details, the number of users in each power grid, user types and distribution, and further divide the photovoltaic development potential for industrial / commercial users into low-voltage industrial / commercial and medium-voltage industrial / commercial photovoltaic development potential.

[0016] Step 2: Based on the number of users, user types, number of users and user types of distribution transformers and medium-voltage lines in each power grid of the area to be evaluated, as well as the photovoltaic development potential obtained in Step 1, calculate the remaining photovoltaic development potential around each distribution transformer and medium-voltage line.

[0017] Step 3: Based on the current status of distribution transformers and medium-voltage line equipment, and in conjunction with the current photovoltaic development situation, calculate the remaining distributed photovoltaic capacity that can be connected to the distribution transformers and medium-voltage lines, and compare it with the remaining photovoltaic development potential around the distribution transformers and medium-voltage lines to determine whether there is a distributed photovoltaic carrying capacity problem.

[0018] Furthermore, in step 1, the calculation of the residential and commercial photovoltaic development potential includes:

[0019] Obtain the roof area of ​​each power grid residential building and commercial and industrial roof area Obtain the installed capacity per unit area of ​​photovoltaic panels ;

[0020] Set the proportion of residential photovoltaic development in the area to be evaluated and the proportion of industrial and commercial photovoltaic development ;

[0021] According to the formula Calculate the potential for residential photovoltaic development ;

[0022] According to the formula Calculate the development potential of industrial and commercial photovoltaics .

[0023] Furthermore, in step 1, the further division of industrial and commercial photovoltaic development potential into low-voltage industrial and commercial and medium-voltage industrial and commercial photovoltaic development potential includes:

[0024] Calculate the average installed capacity per low-voltage distributed photovoltaic (PV) industrial and commercial user based on the total installed capacity and number of users within the power grid or the district / county to which the power grid belongs. ;

[0025] Calculate the average installed capacity per household of medium-voltage distributed photovoltaic industrial and commercial users based on the total installed capacity and number of users in the power grid or the district / county to which the power grid belongs. ;

[0026] Calculate the proportion of low-voltage industrial and commercial photovoltaic development potential separately. The proportion of medium-voltage industrial and commercial photovoltaic development potential :

[0027]

[0028]

[0029] in, This refers to the number of low-voltage industrial and commercial users; This refers to the number of medium-voltage industrial and commercial users;

[0030] According to the formula Calculate the development potential of low-voltage industrial and commercial photovoltaic systems. ;

[0031] According to the formula Calculate the development potential of medium-voltage industrial and commercial photovoltaic systems. .

[0032] Furthermore, in step 2, the remaining photovoltaic development potential around the distribution transformer includes the remaining photovoltaic development potential around the public distribution transformer and the remaining photovoltaic development potential around the dedicated distribution transformer; the sum of the remaining photovoltaic development potential around the public distribution transformer and the remaining photovoltaic development potential around the dedicated distribution transformer is the remaining photovoltaic development potential around the medium-voltage line.

[0033] Furthermore, the remaining photovoltaic development potential around the public distribution transformer = the remaining photovoltaic development potential of low-voltage industrial and commercial transformers under the public distribution transformer + the remaining photovoltaic development potential of residential transformers under the rural power grid transformers - the currently developed photovoltaic capacity under the public distribution transformers;

[0034] Remaining photovoltaic development potential around dedicated distribution transformers = Distributed photovoltaic potential around dedicated distribution transformers - Current developed photovoltaic capacity around dedicated distribution transformers

[0035] The potential of distributed photovoltaic power generation in dedicated distribution transformers is obtained by multiplying the ratio of the capacity of dedicated distribution transformers to the total capacity of dedicated distribution transformers in the power grid by the potential for medium-voltage industrial and commercial photovoltaic development within the power grid.

[0036] Furthermore, the steps for obtaining the remaining photovoltaic development potential of residents under the rural power grid distribution transformer are as follows:

[0037] Based on the number of residential users and the number of installed capacity of distributed photovoltaic users under each rural power grid distribution transformer, calculate the number of remaining undeveloped photovoltaic residential users under each rural power grid distribution transformer.

[0038] The number of remaining undeveloped photovoltaic residential users under each rural power grid distribution transformer is summed to obtain the number of remaining undeveloped photovoltaic residential users under the corresponding power supply grid.

[0039] Calculate the remaining photovoltaic development potential of residents under the power grid based on the residential photovoltaic development potential and the current developed photovoltaic capacity of residents.

[0040] The remaining photovoltaic development potential of residents under the rural power grid distribution transformer is calculated based on the ratio of the number of remaining undeveloped photovoltaic residents under the power supply grid to the number of remaining undeveloped photovoltaic residents under the power supply grid and the remaining photovoltaic development potential of residents under the power supply grid.

[0041] Furthermore, the steps for acquiring the remaining photovoltaic development potential of low-voltage industrial and commercial applications under public distribution transformers are as follows:

[0042] Based on the number of industrial and commercial users and the installed capacity of industrial and commercial distributed photovoltaic users under each public distribution transformer, calculate the number of remaining undeveloped industrial and commercial photovoltaic users under each public distribution transformer.

[0043] The number of remaining undeveloped industrial and commercial photovoltaic users under each public distribution transformer is summed to obtain the number of remaining undeveloped industrial and commercial users under the corresponding power supply grid.

[0044] Based on the photovoltaic development potential of low-voltage industrial and commercial enterprises under the power grid and the current developed photovoltaic capacity of low-voltage industrial and commercial enterprises, calculate the remaining photovoltaic development potential of low-voltage industrial and commercial enterprises under the power grid.

[0045] The remaining photovoltaic development potential of low-voltage industrial and commercial users under public distribution transformers is calculated based on the ratio of the number of undeveloped photovoltaic users in industrial and commercial sectors under public distribution transformers to the number of undeveloped industrial and commercial users in their respective power supply grids, as well as the remaining photovoltaic development potential of low-voltage industrial and commercial users under the power supply grids.

[0046] Furthermore, in step 3, the calculation of the remaining distributed photovoltaic capacity that can be connected to the distribution transformer and medium-voltage line includes:

[0047] (1) Based on the current installed distributed photovoltaic operation data, determine the moment of maximum photovoltaic power generation in the area to be evaluated, and calculate the power generation efficiency of the i-th distribution transformer in the area at that moment. and photovoltaic power generation efficiency of the transformer layer :

[0048]

[0049] in, Let be the power generation efficiency of the i-th distribution transformer in this region. Let be the photovoltaic power generation capacity of the i-th distribution transformer in this region at the maximum power generation time. This represents the sum of the photovoltaic installed capacity under this distribution transformer. Power generation efficiency of all distribution transformers The average value;

[0050] (2) Calculate the photovoltaic power generation efficiency of medium-voltage lines. The average value was taken as the line-level photovoltaic power generation efficiency. ;

[0051]

[0052] in, This represents the photovoltaic power generation capacity on medium-voltage line j at the maximum power generation time. This represents the sum of the photovoltaic installed capacity on medium-voltage line j;

[0053] (3) Based on the operating conditions of each distribution transformer, the minimum load at noon is obtained as the calculation benchmark load. Based on the calculation benchmark load, distribution transformer capacity, and distribution transformer photovoltaic power generation efficiency of each distribution transformer, combined with the maximum backfeed load rate limit of the distribution transformer in the region, the remaining distributed photovoltaic capacity that can be connected to the distribution transformer is calculated. :

[0054]

[0055] in, To calculate the baseline load for the distribution transformer, This is the absolute value of the maximum reverse load rate limit for distribution network equipment. This refers to the rated capacity of the distribution transformer.

[0056] (4) Based on the operating conditions of each medium-voltage line, the minimum load at noon is obtained as the calculation benchmark load. Based on the calculation benchmark load, line capacity, and line photovoltaic power generation efficiency of each line, combined with the maximum backfeed load rate limit of the line in the region, the remaining distributed photovoltaic capacity that can be connected to the medium-voltage line is calculated. ;

[0057]

[0058] in, Calculate the baseline load for medium-voltage lines. This refers to the rated capacity of medium-voltage lines.

[0059] Furthermore, in step 3, it is determined whether there is a distributed photovoltaic carrying capacity problem, specifically as follows:

[0060] Compare the remaining distributed photovoltaic (PV) capacity of the distribution transformer with the remaining PV development potential in its surrounding area. If the remaining distributed PV capacity of the distribution transformer is less than the remaining PV development potential in its surrounding area, then the equipment is unlikely to meet future distributed PV development needs, indicating a distributed PV carrying capacity problem. If the remaining distributed PV capacity is less than 0, then the equipment has a serious distributed PV carrying capacity problem. Similarly, compare the remaining distributed PV capacity of the medium-voltage line with the remaining PV development potential in its surrounding area. If the remaining distributed PV capacity of the medium-voltage line is less than the remaining PV development potential in its surrounding area, then the equipment is unlikely to meet future distributed PV development needs, indicating a distributed PV carrying capacity problem. If the remaining distributed PV capacity of the medium-voltage line is less than 0, then the equipment has a serious distributed PV carrying capacity problem.

[0061] In a second aspect, the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method described thereon.

[0062] The present invention has the following beneficial effects: 1. It realizes the refinement and accuracy of photovoltaic potential assessment: By distinguishing between residential and industrial and commercial users, and further subdividing industrial and commercial potential according to voltage level, the present invention fully considers the installation characteristics of different user types, overcomes the problem of potential estimation distortion caused by user type confusion in the existing macro assessment methods, and makes the potential assessment results closer to reality.

[0063] 2. Achieved precise positioning of load-bearing capacity issues: By calculating the remaining photovoltaic development potential "around" distribution transformers and medium-voltage lines at each level, this invention scientifically and rationally allocates the macro-regional potential to specific power distribution equipment, thereby shifting the assessment dimension of load-bearing capacity issues from "region" to "equipment," achieving precise identification of bottleneck equipment and providing clear targets for power distribution network transformation.

[0064] 3. Achieves practicality and reliability in capacity calculation: By introducing the concept of "power generation efficiency" and using the minimum midday load and maximum backfeed load rate limits to calculate the remaining connectable capacity, this invention fully considers the actual output characteristics of photovoltaic power generation and the backfeed constraints for safe operation of the distribution network, making the calculation results more consistent with engineering practice and more scientific and reliable than the traditional simple capacity subtraction method.

[0065] 4. A hierarchical and systematic assessment and diagnosis logic has been constructed: This invention provides a clear and operable diagnostic path that can systematically screen out load-bearing capacity problems of different degrees of severity, and the assessment conclusions are clear and highly instructive.

[0066] 5. In summary, this invention successfully achieves a "quasi-equipment-level" assessment accuracy without relying on complex simulation models. The method has moderate data requirements, efficient calculation processes, and clear and specific conclusions, perfectly filling the technical gap between existing macro-level assessments and detailed simulations. It is particularly suitable for power supply departments to conduct routine and rapid screening and assessment of the distributed photovoltaic (PV) carrying capacity of large-scale distribution networks. This method solves the problem of difficulty in early assessment of distribution network carrying capacity in the context of large-scale growth in distributed PV installed capacity, improving the efficiency of distribution network construction and renovation for distributed PV development. Attached Figure Description

[0067] Figure 1 This is a flowchart of a method for assessing the carrying capacity of distributed photovoltaic power in a current power distribution network. Detailed Implementation

[0068] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0069] like Figure 1 As shown, a method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks includes the following steps:

[0070] Step 1: Differentiate between residential and industrial / commercial users, collect the roof area of ​​each power grid in the area to be evaluated, and calculate the photovoltaic development potential for residential and industrial / commercial users; combine the current photovoltaic installation details, the number of users in each power grid, user types and distribution, and further divide the photovoltaic development potential for industrial / commercial users into low-voltage industrial / commercial and medium-voltage industrial / commercial photovoltaic development potential.

[0071] Step 1.1: Calculate the potential for residential and commercial photovoltaic development.

[0072] Obtain the roof area of ​​each power grid residential building and commercial and industrial roof area Obtain the installed capacity per unit area of ​​photovoltaic panels Set the proportion of residential photovoltaic development in the area to be evaluated. and the proportion of industrial and commercial photovoltaic development Calculate the residential photovoltaic development potential using the following formula. Industrial and commercial photovoltaic development potential :

[0073]

[0074]

[0075] Among them, the proportion of residential photovoltaic development and the proportion of industrial and commercial photovoltaic development The assessment is set as needed based on the assessment of the region to be assessed. The comprehensive assessment takes into account (1) the local roof conditions (whether the roof is suitable for installing photovoltaic panels, and the percentage of the roof area where photovoltaic panels can be installed); (2) the local users' willingness to install photovoltaic panels. The formula can be set as follows:

[0076] Photovoltaic development ratio = Proportion of suitable photovoltaic rooftops × Estimated proportion of installable photovoltaic panel area suitable for photovoltaic rooftops × Proportion of users willing to install photovoltaics among users suitable for photovoltaic rooftops.

[0077] Step 1.2 further divides the development potential of industrial and commercial photovoltaics into low-voltage industrial and commercial photovoltaic development potential and medium-voltage industrial and commercial photovoltaic development potential.

[0078] Step 1.2.1: Calculate the average installed capacity per household for low-voltage distributed photovoltaic industrial and commercial users. :

[0079] Average installed capacity of low-voltage distributed photovoltaic industrial and commercial users =Total installed capacity of low-voltage distributed photovoltaic industrial and commercial users in the power supply grid or the district / county to which the power supply grid belongs ÷Number of low-voltage distributed photovoltaic industrial and commercial users in the power supply grid or the district / county to which the power supply grid belongs

[0080] Step 1.2.2: Calculate the average installed capacity per commercial and industrial user of medium-voltage distributed photovoltaic power. :

[0081] Average installed capacity of medium-voltage distributed photovoltaic industrial and commercial users =Total installed capacity of medium-voltage distributed photovoltaic industrial and commercial users in the power grid or the district / county to which the power grid belongs ÷Number of installed medium-voltage distributed photovoltaic industrial and commercial users in the power grid or the district / county to which the power grid belongs;

[0082] The total installed capacity of the power grid or the district / county to which the power grid belongs and the number of users are obtained through the current photovoltaic installation details. The current photovoltaic installation details include (1) photovoltaic name; (2) photovoltaic access transformer, line name, power grid to which it belongs, and district / county to which it belongs; (3) photovoltaic installation nature (residential, industrial and commercial); (4) photovoltaic installation capacity; (5) voltage level.

[0083] Steps 1, 2, and 3: Calculate the proportion of low-voltage industrial and commercial photovoltaic development potential. The proportion of medium-voltage industrial and commercial photovoltaic development potential :

[0084]

[0085]

[0086] in, This refers to the number of low-voltage industrial and commercial users; This refers to the number of medium-voltage industrial and commercial users;

[0087] Step 1.2.4: Calculate the development potential of low-voltage industrial and commercial photovoltaic systems. Medium-voltage industrial and commercial photovoltaic development potential :

[0088]

[0089]

[0090] Step 2: Based on the number of users, user types, number of users and user types of distribution transformers and medium-voltage lines in each power grid of the area to be evaluated, as well as the photovoltaic development potential obtained in Step 1, calculate the remaining photovoltaic development potential around each distribution transformer and medium-voltage line.

[0091] Step 2.1: Calculate the remaining photovoltaic development potential for residents under the rural power grid distribution transformer.

[0092] Step 2.1.1: Calculate the number of remaining undeveloped photovoltaic residential users under each rural power grid distribution transformer:

[0093] The number of remaining undeveloped photovoltaic residential users under each rural power grid distribution transformer = the number of residential users under each rural power grid distribution transformer - the number of installed capacity of residential distributed photovoltaic users;

[0094] Step 2.1.2: Add up the number of remaining undeveloped photovoltaic residential users under each rural power grid distribution transformer to obtain the number of remaining undeveloped photovoltaic residential users under the corresponding power supply grid;

[0095] Step 2.1.3, calculate the remaining photovoltaic development potential for residents under the power supply grid:

[0096] Remaining Residential Photovoltaic Development Potential under the Power Supply Grid = Residential Photovoltaic Development Potential under the Power Supply Grid - Current residential photovoltaic capacity

[0097] Step 2.1.4, calculate the remaining photovoltaic development potential for residents under the rural power grid distribution transformer:

[0098] The remaining photovoltaic development potential of residents under the rural power grid distribution transformer = the number of remaining undeveloped photovoltaic residential users under the rural power grid distribution transformer ÷ the number of remaining undeveloped photovoltaic residential users under the power supply grid × the remaining photovoltaic development potential of residents under the power supply grid;

[0099] Step 2.2: Calculate the remaining photovoltaic development potential for low-voltage industrial and commercial applications under public distribution transformers.

[0100] Step 2.2.1, calculate the number of remaining undeveloped photovoltaic users in industrial and commercial sectors under each public distribution transformer:

[0101] Number of undeveloped industrial and commercial photovoltaic users under each public distribution transformer = Number of industrial and commercial users under each public distribution transformer - Installed capacity of industrial and commercial distributed photovoltaic users

[0102] Step 2.2.2: Add up the number of remaining undeveloped industrial and commercial photovoltaic users under each public distribution transformer to obtain the number of remaining undeveloped industrial and commercial users under the corresponding power supply grid;

[0103] Step 2.2.3, calculate the remaining photovoltaic development potential for low-voltage industrial and commercial applications under the power grid:

[0104] The remaining photovoltaic development potential for low-voltage industrial and commercial applications under the power grid = the photovoltaic development potential for low-voltage industrial and commercial applications under the power grid P icl0 - Current low-voltage industrial and commercial photovoltaic capacity

[0105] Step 2.2.4, calculate the remaining photovoltaic development potential for low-voltage industrial and commercial applications under public distribution transformers:

[0106] The remaining photovoltaic development potential for low-voltage industrial and commercial users under public distribution transformers = Number of remaining undeveloped photovoltaic users in industrial and commercial sectors under public distribution transformers ÷ Number of remaining undeveloped industrial and commercial users under the corresponding power grid × Remaining photovoltaic development potential for low-voltage industrial and commercial users under the power grid

[0107] Step 2.3, calculate the remaining photovoltaic development potential around the public distribution transformer:

[0108] Remaining photovoltaic development potential around public distribution transformers = Remaining photovoltaic development potential for low-voltage industrial and commercial applications under public distribution transformers + Remaining photovoltaic development potential for residential applications under rural distribution transformers - Current developed photovoltaic capacity under public distribution transformers

[0109] Step 2.4, calculate the remaining photovoltaic development potential around the dedicated distribution transformer.

[0110] Remaining photovoltaic development potential around dedicated distribution transformers =Potential of Distributed Photovoltaics Using Dedicated Distribution Transformers - Current Developed Photovoltaic Capacity Using Dedicated Distribution Transformers

[0111] Among them, the potential of distributed photovoltaic power generation under dedicated distribution transformers = capacity of dedicated distribution transformers ÷ total capacity of dedicated distribution transformers in the power grid × potential for medium-voltage industrial and commercial photovoltaic development under the power grid ;

[0112] Step 2.5, calculate the remaining photovoltaic potential around the line.

[0113] Remaining photovoltaic potential around the line = Remaining photovoltaic development potential around public distribution transformers + Remaining photovoltaic development potential around dedicated distribution transformers

[0114] Step 3: Based on the current status of distribution transformers and medium-voltage line equipment, and in conjunction with the current photovoltaic development situation, calculate the remaining distributed photovoltaic capacity that can be connected to the distribution transformers and medium-voltage lines, and compare it with the surrounding photovoltaic development potential to determine whether there is a distributed photovoltaic carrying capacity problem.

[0115] Step 3.1: Based on the currently installed distributed photovoltaic (PV) operation data, determine the moment of maximum PV power generation in the area to be evaluated, and calculate the power generation efficiency of the i-th distribution transformer in that area at that moment. and photovoltaic power generation efficiency of the transformer layer :

[0116]

[0117] in, Let be the power generation efficiency of the i-th distribution transformer in this region. Let be the photovoltaic power generation capacity of the i-th distribution transformer in this region at the maximum power generation time. This represents the sum of the photovoltaic installed capacity under this distribution transformer. Power generation efficiency of all distribution transformers The average value;

[0118] Step 3.2, calculate the photovoltaic power generation efficiency at the medium-voltage line level. The average value was taken as the line-level photovoltaic power generation efficiency. ;

[0119]

[0120] in, This represents the photovoltaic power generation capacity on medium-voltage line j at the maximum power generation time. This represents the sum of the photovoltaic installed capacity on medium-voltage line j;

[0121] Step 3.3: Obtain the lowest load at noon based on the operating status of each distribution transformer as the calculation baseline load. Calculate the remaining usable distributed photovoltaic capacity of each distribution transformer based on its baseline load, capacity, and photovoltaic power generation efficiency, taking into account the maximum backfeed load rate limit for the distribution transformer in the region. :

[0122]

[0123] in, To calculate the baseline load for the distribution transformer, This is the absolute value of the maximum reverse load rate limit for distribution network equipment. This refers to the rated capacity of the distribution transformer.

[0124] Step 3.4: Obtain the minimum load at noon for each medium-voltage line based on its operating status, and use it as the calculation baseline load. Based on the calculated baseline load, line capacity, and photovoltaic power generation efficiency for each line, and considering the maximum backfeed load rate limit for the region, calculate the remaining usable distributed photovoltaic capacity for the medium-voltage lines. ;

[0125]

[0126] in, Calculate the baseline load for medium-voltage lines. This refers to the rated capacity of medium-voltage lines.

[0127] Step 3.5 compares the remaining usable distributed photovoltaic (PV) capacity of the distribution transformer and medium-voltage lines with the surrounding remaining PV potential. If the remaining usable PV capacity is less than the surrounding remaining PV potential, the equipment is unlikely to meet future distributed PV development and has a distributed PV carrying capacity problem. If the remaining usable PV capacity is less than 0, the equipment has already experienced backfeeding overload due to distributed power supply access and other reasons, and has a serious distributed PV carrying capacity problem. Distribution transformer problems are resolved through new distribution transformer capacity expansion projects, while line problems are resolved through grid adjustment projects.

[0128] Example

[0129] Data on the current status of the distribution network is obtained through the power grid's internal information acquisition system. The invention is further illustrated below with reference to accompanying figures and a practical example (this example uses information such as rooftop area, current status of distributed photovoltaic development, and distribution network equipment in a certain district / county). The method includes the following steps:

[0130] Step 1: Based on the survey results, the installed capacity per unit area of ​​photovoltaic panels in this region. Approximately 200W / square meter, residential photovoltaic development ratio The proportion of industrial and commercial photovoltaic development is approximately 0.1. The potential proportion of low-voltage industrial and commercial photovoltaic development is approximately 0.4. The proportion of medium-voltage industrial and commercial photovoltaic development potential is approximately 0.1. The value is approximately 0.2. Data on the rooftop area of ​​residential and commercial buildings in various power supply grids of a certain district and county were collected and the photovoltaic potential was calculated as shown in Table 1.

[0131]

[0132] Step 2: Based on the number of users, user types, and the number and type of downstream users of distribution transformers and medium-voltage lines in each power grid of the area to be evaluated, the remaining photovoltaic development potential around each distribution transformer and medium-voltage line is calculated as shown in Tables 2 and 3.

[0133]

[0134]

[0135] Step 3: Based on the current status of distribution transformers and medium-voltage line equipment, and in conjunction with the current photovoltaic development situation, calculate the remaining available distributed photovoltaic capacity as shown in Tables 4 and 5.

[0136]

[0137]

[0138] Step 4: Compare the remaining distributed photovoltaic access capacity of the power grid equipment with the photovoltaic development potential of its surroundings. After diagnosis, there is no photovoltaic carrying capacity problem at the current line level, and the photovoltaic carrying capacity problem at the distribution transformer level is shown in Table 6.

[0139]

[0140] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks, characterized in that, Includes the following steps: Step 1: Differentiate between residential and industrial / commercial users, collect the roof area of ​​each power grid in the area to be evaluated, and calculate the photovoltaic development potential for residential and industrial / commercial users; combine the current photovoltaic installation details, the number of users in each power grid, user types and distribution, and further divide the photovoltaic development potential for industrial / commercial users into low-voltage industrial / commercial and medium-voltage industrial / commercial photovoltaic development potential. Step 2: Based on the number of users, user types, number of users and user types of distribution transformers and medium-voltage lines in each power grid of the area to be evaluated, as well as the photovoltaic development potential obtained in Step 1, calculate the remaining photovoltaic development potential around each distribution transformer and medium-voltage line. Step 3: Based on the current status of distribution transformers and medium-voltage line equipment, and in conjunction with the current photovoltaic development situation, calculate the remaining distributed photovoltaic capacity that can be connected to the distribution transformers and medium-voltage lines, and compare it with the remaining photovoltaic development potential around the distribution transformers and medium-voltage lines to determine whether there is a distributed photovoltaic carrying capacity problem.

2. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 1, characterized in that, In step 1, calculating the potential for residential and commercial photovoltaic development includes: Obtain the roof area of ​​each power grid residential building and commercial and industrial roof area Obtain the installed capacity per unit area of ​​photovoltaic panels ; Set the proportion of residential photovoltaic development in the area to be evaluated and the proportion of industrial and commercial photovoltaic development ; According to the formula Calculate the potential for residential photovoltaic development ; According to the formula Calculate the development potential of industrial and commercial photovoltaics .

3. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 2, characterized in that, In step 1, the further division of industrial and commercial photovoltaic development potential into low-voltage industrial and commercial and medium-voltage industrial and commercial photovoltaic development potential includes: Calculate the average installed capacity per low-voltage distributed photovoltaic (PV) industrial and commercial user based on the total installed capacity and number of users within the power grid or the district / county to which the power grid belongs. ; Calculate the average installed capacity per household of medium-voltage distributed photovoltaic industrial and commercial users based on the total installed capacity and number of users in the power grid or the district / county to which the power grid belongs. ; Calculate the proportion of low-voltage industrial and commercial photovoltaic development potential separately. The proportion of medium-voltage industrial and commercial photovoltaic development potential : ； ； in, This refers to the number of low-voltage industrial and commercial users; This refers to the number of medium-voltage industrial and commercial users; According to the formula Calculate the development potential of low-voltage industrial and commercial photovoltaic systems. ; According to the formula Calculate the development potential of medium-voltage industrial and commercial photovoltaic systems. .

4. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 1, characterized in that, In step 2, the remaining photovoltaic development potential around the distribution transformer includes the remaining photovoltaic development potential around the public distribution transformer and the remaining photovoltaic development potential around the dedicated distribution transformer; the sum of the remaining photovoltaic development potential around the public distribution transformer and the remaining photovoltaic development potential around the dedicated distribution transformer is the remaining photovoltaic development potential around the medium-voltage line.

5. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 4, characterized in that, The remaining photovoltaic development potential around the public distribution transformer = the remaining photovoltaic development potential of low-voltage industrial and commercial grids under the public distribution transformer + the remaining photovoltaic development potential of residential grids under rural distribution transformers - the currently developed photovoltaic capacity under the public distribution transformer; Remaining photovoltaic development potential around dedicated distribution transformers = Distributed photovoltaic potential of dedicated distribution transformers - Current photovoltaic capacity developed by dedicated distribution transformers; The potential of distributed photovoltaic power generation in dedicated distribution transformers is obtained by multiplying the ratio of the capacity of dedicated distribution transformers to the total capacity of dedicated distribution transformers in the power grid by the potential for medium-voltage industrial and commercial photovoltaic development within the power grid.

6. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 5, characterized in that, The steps to obtain the remaining photovoltaic development potential for residential use under the rural power grid distribution transformer are as follows: Based on the number of residential users and the number of installed capacity of distributed photovoltaic users under each rural power grid distribution transformer, calculate the number of remaining undeveloped photovoltaic residential users under each rural power grid distribution transformer. The number of remaining undeveloped photovoltaic residential users under each rural power grid distribution transformer is summed to obtain the number of remaining undeveloped photovoltaic residential users under the corresponding power supply grid. Calculate the remaining photovoltaic development potential of residents under the power grid based on the residential photovoltaic development potential and the current developed photovoltaic capacity of residents. The remaining photovoltaic development potential of residents under the rural power grid distribution transformer is calculated based on the ratio of the number of remaining undeveloped photovoltaic residents under the power supply grid to the number of remaining undeveloped photovoltaic residents under the power supply grid and the remaining photovoltaic development potential of residents under the power supply grid.

7. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 5, characterized in that, The steps to identify the remaining photovoltaic development potential in low-voltage industrial and commercial applications under public distribution transformers are as follows: Based on the number of industrial and commercial users and the installed capacity of industrial and commercial distributed photovoltaic users under each public distribution transformer, calculate the number of remaining undeveloped industrial and commercial photovoltaic users under each public distribution transformer. The number of remaining undeveloped industrial and commercial photovoltaic users under each public distribution transformer is summed to obtain the number of remaining undeveloped industrial and commercial users under the corresponding power supply grid. Based on the photovoltaic development potential of low-voltage industrial and commercial enterprises under the power grid and the current developed photovoltaic capacity of low-voltage industrial and commercial enterprises, calculate the remaining photovoltaic development potential of low-voltage industrial and commercial enterprises under the power grid. The remaining photovoltaic development potential of low-voltage industrial and commercial users under public distribution transformers is calculated based on the ratio of the number of undeveloped photovoltaic users in industrial and commercial sectors under public distribution transformers to the number of undeveloped industrial and commercial users in their respective power supply grids, as well as the remaining photovoltaic development potential of low-voltage industrial and commercial users under the power supply grids.

8. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 1, characterized in that, Step 3, calculating the remaining distributed photovoltaic capacity that can be connected to distribution transformers and medium-voltage lines includes: (1) Based on the current installed distributed photovoltaic operation data, determine the moment of maximum photovoltaic power generation in the area to be evaluated, and calculate the power generation efficiency of the i-th distribution transformer in the area at that moment. and photovoltaic power generation efficiency of the transformer layer : ； in, Let be the power generation efficiency of the i-th distribution transformer in this region. Let be the photovoltaic power generation capacity of the i-th distribution transformer in this region at the maximum power generation time. This represents the sum of the photovoltaic installed capacity under this distribution transformer. Power generation efficiency of all distribution transformers The average value; (2) Calculate the photovoltaic power generation efficiency of medium-voltage lines. The average value was taken as the line-level photovoltaic power generation efficiency. ; ； in, This represents the photovoltaic power generation capacity on medium-voltage line j at the maximum power generation time. This represents the sum of the photovoltaic installed capacity on medium-voltage line j; (3) Based on the operating conditions of each distribution transformer, the minimum load at noon is obtained as the calculation benchmark load. Based on the calculation benchmark load, distribution transformer capacity, and distribution transformer photovoltaic power generation efficiency of each distribution transformer, combined with the maximum backfeed load rate limit of the distribution transformer in the region, the remaining distributed photovoltaic capacity that can be connected to the distribution transformer is calculated. : ； in, To calculate the baseline load for the distribution transformer, This is the absolute value of the maximum reverse load rate limit for distribution network equipment. This refers to the rated capacity of the distribution transformer; (4) Based on the operating conditions of each medium-voltage line, the minimum load at noon is obtained as the calculation benchmark load. Based on the calculation benchmark load, line capacity, and line photovoltaic power generation efficiency of each line, combined with the maximum backfeed load rate limit of the line in the region, the remaining distributed photovoltaic capacity that can be connected to the medium-voltage line is calculated. ; ； in, Calculate the baseline load for medium-voltage lines. This refers to the rated capacity of medium-voltage lines.

9. The method for assessing the carrying capacity of distributed photovoltaic power in existing distribution networks according to claim 1, characterized in that, In step 3, it is determined whether there is a distributed photovoltaic carrying capacity problem, specifically: Compare the remaining distributed photovoltaic (PV) capacity of the distribution transformer with the remaining PV development potential in its surrounding area. If the remaining distributed PV capacity of the distribution transformer is less than the remaining PV development potential in its surrounding area, then the equipment is unlikely to meet the future distributed PV development and has a distributed PV carrying capacity problem; if the remaining PV capacity is less than 0, then the equipment has a serious distributed PV carrying capacity problem. Similarly, compare the remaining distributed PV capacity of the medium-voltage line with the remaining PV development potential in its surrounding area. If the remaining distributed PV capacity of the medium-voltage line is less than the remaining PV development potential in its surrounding area, then the equipment is unlikely to meet the future distributed PV development and has a distributed PV carrying capacity problem; if the remaining PV capacity of the medium-voltage line is less than 0, then the equipment has a serious distributed PV carrying capacity problem.

10. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-9.

Images