Calculation method of theoretical line loss in distribution network based on typical equivalent load distribution curve

Abstract

The present invention proposes a distribution network theoretical line loss calculation method based on a typical equivalent load distribution curve, including: establishing an equivalent load distribution curve for describing load distribution; clustering the electrical equivalent load distribution curves established based on data at different times of the same distribution line; using the largest number of equivalent load distribution curves obtained by clustering as the benchmark classification of the distribution line, and using the cluster center as the benchmark curve of the distribution line; comparing the line loss fluctuations between each type of curve and the benchmark curve, and quantifying the line loss change rate; and obtaining the line loss estimation result according to the line loss change rate under the corresponding situation. The line loss of the entire distribution network can be estimated in a relatively short time.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network, and in particular relates to a method for calculating theoretical line loss of a distribution network based on a typical equivalent load distribution curve. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The losses in the power system mainly include non-technical losses and technical losses. Non-technical losses are mainly caused by electricity theft, inaccurate metering systems, inaccurate settlement systems, etc. Technical losses are divided into variable losses and fixed losses, which are mainly energy losses caused by heat generation in various electrical equipment such as lines, transformers, capacitors, etc. when the power system is running.

[0004] The above technical losses can be calculated based on the structural parameters of the power system and operating parameters such as load distribution. Technical losses are also called theoretical line losses, and their calculation has an important impact on the planning, design, and operation management of the power system. In recent years, in particular, a large number of distributed renewable power sources have been connected to the distribution network, and the load distribution along the distribution lines has fluctuated frequently, which has brought great difficulties to the calculation of theoretical line losses, making it difficult to evaluate the rationality of the distributed power access method, and is not conducive to improving the economic efficiency of the distribution network operation.

[0005] In the existing technology, power flow analysis is the most accurate method for calculating theoretical line loss of power grids. However, the power flow analysis method must master the exact line parameters, power consumption data of each load point, etc., and has high requirements for data collection. It is not suitable for large-scale distribution networks with low level of information automation collection. Therefore, the current distribution system line loss has the problem of large calculation scale and drastic changes in operating status due to the influence of renewable power generation.

[0006] In addition, load distribution is the main factor affecting the line loss of the distribution network, and is also the main factor closely related to the changes in the operating status of the distribution network. Therefore, how to consider load distribution in the theoretical calculation of line loss is an issue that should be focused on in establishing a new fast calculation method.

[0007] Some literature in the prior art proposes a method of classifying load distribution in the theoretical calculation of distribution network line loss under the premise of assuming uniform distribution of line impedance. However, these classifications are relatively conceptual, which is to divide the load distribution into several types set in advance and give the corresponding distribution functions. Therefore, although these studies have provided a method for fast calculation, the classification of load distribution is not comprehensive enough and is not representative enough for the complex and changeable actual distribution network, and cannot be competent for the line loss estimation under various load distribution conditions in the actual distribution system.

[0008] In recent years, with the large-scale access of distributed power sources, the load distribution of distribution network lines has more types of changes. Taking these changes into comprehensive consideration, how to fully grasp the line loss situation of the actual distribution network and find a fast calculation method for large-scale estimation of line loss is the main technical problem that needs to be solved. Summary of the invention

[0009] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a method for calculating the theoretical line loss of a distribution network based on a typical equivalent load distribution curve, so as to complete a large-scale estimation in a short time and quickly grasp the changes in the line loss of the distribution system.

[0010] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0011] In the first aspect, a method for calculating theoretical line loss of a distribution network based on a typical equivalent load distribution curve is disclosed, including:

[0012] Establishing equivalent load distribution curves for describing load distribution;

[0013] Clustering the electrical equivalent load distribution curves established based on the data of the same distribution line at different times;

[0014] The equivalent load distribution curve of the largest number obtained by clustering is used as the benchmark classification of the distribution line, and its cluster center is used as the benchmark curve of the distribution line;

[0015] Compare the line loss fluctuations between various curves and the benchmark curve, and quantify the line loss change rate;

[0016] The line loss estimation result is obtained based on the line loss change rate in the corresponding situation.

[0017] As a further technical solution, it also includes:

[0018] Extracting the benchmark equivalent load distribution curve and its benchmark curve of each distribution line to form an equivalent load distribution curve set of the distribution network;

[0019] By comparing the equivalent load distribution curve at a certain moment with the equivalent load distribution curve set of the line, the line loss of each line is estimated.

[0020] As a further technical solution, when establishing an equivalent load distribution curve for describing load distribution, the electrical equivalent load distribution curve is extracted based on the distribution system structure diagram and the load parameters of specific load points.

[0021] As a further technical solution, the steps for forming the equivalent load distribution curve are:

[0022] Preprocess the historical data of the power distribution system to obtain the data of each distribution line;

[0023] Convert the physical distance of a line in the power distribution system into electrical distance;

[0024] Taking the electrical distance length as the horizontal axis, the load capacity of each load point on the line is evenly distributed;

[0025] Select a point with equal electrical distance as a new load point, and add up the load capacities of each load on the equivalent load point to obtain the load capacity on the equivalent load point;

[0026] Using this value as the corresponding ordinate value, the values ​​of each equivalent load point are connected to form an electrical equivalent load distribution curve.

[0027] As a further technical solution, the physical distance of a line in the power distribution system is converted into the electrical distance, and the formula is as follows:

[0028] R a L a =r a l a

[0029] Among them, let R a =1Ω, then L a is the electrical equivalent length of line section a, r a is the resistance per unit length of line section a, l a is the physical length of line segment a;

[0030] That is, the electrical length of a section of the line is:

[0031]

[0032] As a further technical solution, when clustering the electrical equivalent load distribution curves, the slope of the electrical equivalent load distribution curve between every two equivalent load points is used as a clustering feature to cluster the electrical equivalent load distribution curves.

[0033] As a further technical solution, the line loss fluctuations between various curves and the benchmark curve are compared, and the line loss change rate is quantified. The specific method is as follows:

[0034] Compare all types of equivalent load distribution curves except the benchmark curve with the benchmark curve, calculate the deviation of line loss under each type of curve and the line loss under the benchmark curve, and express it in percentage.

[0035] In the second aspect, a distribution network theoretical line loss calculation system based on a typical equivalent load distribution curve is disclosed, including:

[0036] The equivalent load distribution curve establishing module is configured to: establish an equivalent load distribution curve for describing load distribution;

[0037] The clustering module is configured to: cluster the electrical equivalent load distribution curves established based on the data of the same distribution line at different times;

[0038] The reference curve determination module is configured to: use the equivalent load distribution curve of the largest number obtained by clustering as the reference classification of the distribution line, and use the cluster center as the reference curve of the distribution line;

[0039] The line loss change rate quantification module is configured to: compare the line loss fluctuations between various curves and the reference curve, and quantify the line loss change rate;

[0040] The line loss estimation module is configured to obtain a line loss estimation result according to a line loss change rate under corresponding circumstances.

[0041] One or more of the above technical solutions have the following beneficial effects:

[0042] The present invention processes the original data in the actual distribution network, extracts the equivalent load distribution curve of each line, and establishes the equivalent load distribution curve set of the distribution network, so as to comprehensively and effectively grasp and divide the load distribution of each line of a certain actual distribution system; after clustering the equivalent load distribution curve of each line by using a clustering algorithm, the characteristics of various equivalent load distributions of the distribution system and the influence on line loss can be analyzed more specifically, and the incompatibility that may exist when a fixed load distribution type is used in various distribution networks is solved.

[0043] After the present invention determines the benchmark equivalent load distribution curve of each line, when determining the line loss situation of a certain line at a certain moment, it only needs to compare the equivalent load distribution curve at this moment with each typical curve in the equivalent load distribution curve set of the line, so that the line loss situation of the line at this moment can be estimated, without the need to determine the approximate situation of the line loss through specific numerical calculation, thereby realizing rapid large-scale estimation of line loss, and the line loss situation of the entire distribution network can be estimated in a relatively short time.

[0044] The present invention focuses on analyzing abnormal line loss conditions on the basis of large-scale estimation, and further accurately calculates these lines or areas when necessary, so as to complete large-scale estimation in a short time and quickly grasp the changes in line loss in the distribution system. This is of great significance for comprehensively grasping the line loss conditions of the distribution network and improving the level of line loss management.

[0045] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0047] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the specific implementation process of step four and step five of the embodiment of the present invention. DETAILED DESCRIPTION

[0049] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0050] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0051] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0052] As described in the background technology, the current technical status is that there is currently a lack of fast calculation methods for large-scale estimation of line losses for distribution network systems containing distributed power sources.

[0053] Classification calculation based on load distribution is a feasible solution, but the existing load distribution classification method is not detailed and complete enough to fully reflect the characteristics of various load distributions in the distribution network.

[0054] Embodiment 1

[0055] This embodiment discloses a method for calculating theoretical line loss of a distribution network based on a typical equivalent load distribution curve, including:

[0056] Combining the unevenly distributed impedance of the actual distribution network with the load distribution, a method for establishing an equivalent load distribution curve is proposed to more accurately describe the load distribution.

[0057] Then, a large number of electrical equivalent load distribution curves established based on data of the same line at different times are clustered by clustering algorithm to obtain a typical equivalent load distribution curve;

[0058] Conduct a specific analysis on each type of equivalent load distribution curve, and take the cluster of equivalent load distribution curves with the largest number as the benchmark classification of the line, and take its cluster center as the benchmark curve of the line;

[0059] Compare the line loss fluctuations between various curves and the benchmark curve, and quantify the line loss change rate;

[0060] At any time, once the equivalent load distribution is determined according to the changes in load and renewable power generation, the line loss estimation result can be quickly obtained based on the line loss change rate in the corresponding situation.

[0061] In order to more quickly estimate the line loss of the distribution line at a certain moment, the present embodiment also discloses: extracting the benchmark equivalent load distribution curve and its benchmark curve of each distribution line to form an equivalent load distribution curve set of the distribution network. In the subsequent large-scale line loss estimation, by comparing the equivalent load distribution curve at a certain moment with the equivalent load distribution curve set of the line, a rapid estimation of the line loss of each line is achieved.

[0062] In some possible implementation examples, the electrical equivalent load distribution curve is extracted according to the distribution system structure diagram and the load parameters of the specific load point. Because most distribution networks are radial, a line of the radial distribution network is taken as an example.

[0063] See attached Figure 1 As shown, the specific steps of the above method are as follows:

[0064] Step 1: Preprocess the historical data of an actual distribution system and sort out the data of each line; the data here mainly includes the load conditions of the load points on each feeder line of an actual distribution system, the access capacity and location of distributed power sources, and the line parameters between each load point (resistance value per unit line length).

[0065] Step 2: Convert the physical distance of a line in the power distribution system into electrical distance. The physical distance here is the physical length, which is obtained by actual measurement. The formula is as follows:

[0066] R a L a =r a l a

[0067] Among them, let R a =1Ω, then L a is the electrical equivalent length of line section a, r a is the resistance per unit length of line section a, l a is the physical length of line segment a.

[0068] That is, the electrical length of a section of the line is:

[0069]

[0070] Step 3: Using the electrical distance length as the horizontal axis, evenly distribute the load capacity of each load point on the line;

[0071] Since the electrical distance is the horizontal axis, the resistance value per unit length is equal. In this implementation example, a primary distribution function is selected to apportion the load capacity of each point. The specific distribution function is as follows:

[0072]

[0073] Among them, P represents the net load power at the point, that is, the net value of the load power at the load point and the distributed power access power at the point; L is the electrical length of the line; a is the electrical distance between the load point and the coordinate origin.

[0074] Step 4: Add up the load capacities of each equivalent load point on the line after conversion into electrical distance to obtain the load capacity of the equivalent load point;

[0075] Step 5: Using this value as the corresponding ordinate value, connect the values ​​of each equivalent load point to form an electrical equivalent load distribution curve;

[0076] The specific implementation process of the above steps 4 and 5 is as follows Figure 2 As shown, here is an example of a feeder with four load points:

[0077] Where a, b, c, and d represent the equivalent load points of the feeder, P 1 , P 2 , P 3 , P 4 They represent the load sizes at points a, b, c, and d respectively, and they are spread out according to the above distribution function, as shown by the dotted line in the figure; the values ​​shared at points a, b, c, and d are added together to obtain the equivalent load size at each load point, and the equivalent points are connected to obtain the equivalent load distribution curve, as shown by the solid line curve in the figure.

[0078] Step 6: According to the above steps, the electrical equivalent load distribution curves of the line at different times are extracted to form an equivalent load distribution curve set of the line.

[0079] Step 7: Use the k-means clustering algorithm improved based on the Pearson coefficient. The k-means improved based on the Pearson coefficient is used here. The clustering of the classic k-means clustering algorithm is based on the minimum sum of the Euclidean distance between each sample and its cluster center. The clustering of the k-means clustering algorithm improved based on the Pearson coefficient is based on the maximum sum of the Pearson coefficient between each sample and its cluster center. The Pearson coefficient can reflect the linear correlation between two curves. Using the Pearson coefficient as the clustering basis is better than using the Euclidean distance as the clustering basis in clustering curves with consistent shapes into one category. The slope of the electrical equivalent load distribution curve between each two equivalent load points (the equivalent load point is still the point where the original load is located, but because the distance between any two points is changed from the original physical distance to the electrical distance, it is called the equivalent load point here) is used as the clustering feature to cluster the curves in the curve concentration.

[0080] Step 8: Evaluate and analyze the characteristics of each type of curve, and describe the situation of each type of equivalent load distribution curve, such as which part of the line the load is concentrated on, whether the load distribution is more concentrated or uniform, etc.

[0081] Step 9: Select a classification containing the largest number of equivalent load distribution curves as the baseline classification of the line, and use the cluster center curve in this classification as the baseline curve of the line at this moment.

[0082] Step 10: Compare the typical curves of other types of equivalent load distribution curves with the benchmark curve, calculate the line loss under various curves, and express it in percentage;

[0083] There are many methods for calculating line loss, including the root mean square current method, maximum load loss hour method, equivalent resistance method, power flow calculation, forward and backward substitution method, etc., all of which have high accuracy and certain precision and can be selected according to the type of historical data obtained.

[0084] Step 11: Perform the above steps for each line in the distribution network to be studied to form an equivalent load distribution curve set of the distribution network.

[0085] Step 12: When evaluating the overall line loss situation of the actual distribution network at a certain moment, the equivalent load distribution curves extracted from each line at this moment are compared with their respective equivalent load distribution curve sets to determine the approximate range of the line loss of each line at this moment, thereby realizing a large-scale line loss estimation of the distribution network.

[0086] Embodiment 2

[0087] The purpose of this embodiment is to provide a computing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the program.

[0088] Embodiment 3

[0089] The purpose of this embodiment is to provide a computer-readable storage medium.

[0090] A computer-readable storage medium stores a computer program, which executes the steps of the above method when executed by a processor.

[0091] Embodiment 4

[0092] The purpose of this embodiment is to provide a distribution network theoretical line loss calculation system based on a typical equivalent load distribution curve, including:

[0093] The equivalent load distribution curve establishing module is configured to: establish an equivalent load distribution curve for describing load distribution;

[0094] The clustering module is configured to: cluster the electrical equivalent load distribution curves established based on the data of the same distribution line at different times;

[0095] The reference curve determination module is configured to: use the equivalent load distribution curve of the largest number obtained by clustering as the reference classification of the distribution line, and use the cluster center as the reference curve of the distribution line;

[0096] The line loss change rate quantification module is configured to: compare the line loss fluctuations between various curves and the reference curve, and quantify the line loss change rate;

[0097] The line loss estimation module is configured to obtain a line loss estimation result according to a line loss change rate under corresponding circumstances.

[0098] In the above-mentioned equivalent load distribution curve establishment module, when establishing the equivalent load distribution curve for describing the load distribution, the electrical equivalent load distribution curve is extracted according to the distribution system structure diagram and the load parameters of the specific load points.

[0099] Specifically, the equivalent load distribution curve is formed as follows:

[0100] Preprocess the historical data of the power distribution system to obtain the data of each distribution line;

[0101] Convert the physical distance of a line in the power distribution system into electrical distance;

[0102] Taking the electrical distance length as the horizontal axis, the load capacity of each load point on the line is evenly distributed;

[0103] Select a point with equal electrical distance as a new load point, and add up the load capacities of each load on the equivalent load point to obtain the load capacity on the equivalent load point;

[0104] Using this value as the corresponding ordinate value, the values ​​of each equivalent load point are connected to form an electrical equivalent load distribution curve.

[0105] Among them, the physical distance of a line in the power distribution system is converted into the electrical distance, and the formula is as follows:

[0106] R a L a =r a l a

[0107] Among them, let R a =1Ω, then L a is the electrical equivalent length of line section a, r a is the resistance per unit length of line section a, l a is the physical length of line segment a;

[0108] That is, the electrical length of a section of the line is:

[0109]

[0110] In the above clustering module, when clustering the electrical equivalent load distribution curves, the slope of the electrical equivalent load distribution curves between every two equivalent load points is used as a clustering feature to cluster the electrical equivalent load distribution curves.

[0111] In the above-mentioned line loss change rate quantification module, the line loss fluctuations between various curves and the reference curve are compared, and the line loss change rate is quantified. The specific method is as follows:

[0112] Compare all types of equivalent load distribution curves except the benchmark curve with the benchmark curve, calculate the deviation of line loss under each type of curve and the line loss under the benchmark curve, and express it in percentage.

[0113] The steps involved in the apparatuses of the above embodiments 2, 3 and 4 correspond to the method embodiment 1, and the specific implementation methods can refer to the relevant description part of embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood to include any medium that can store, encode or carry an instruction set for execution by a processor and enable the processor to execute any method in the present invention.

[0114] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0115] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. Theoretical line loss calculation method of distribution network based on typical equivalent load distribution curve, Its characteristics are: include: Establishing equivalent load distribution curves for describing load distribution; The steps for forming the equivalent load distribution curve are: Preprocess the historical data of the power distribution system to obtain the data of each distribution line; Convert the physical distance of a line in the power distribution system into electrical distance; Taking the electrical distance length as the horizontal axis, the load capacity of each load point on the line is evenly distributed; Select a point with equal electrical distance as a new equivalent load point, and add up the load capacities on the equivalent load point to obtain the load capacity on the equivalent load point; Using the load capacity value at the equivalent load point as the corresponding ordinate value, the values ​​of each equivalent load point are connected to form an electrical equivalent load distribution curve; Clustering the electrical equivalent load distribution curves established based on the data of the same distribution line at different times; The equivalent load distribution curve of the largest number obtained by clustering is used as the benchmark classification of the distribution line, and its cluster center is used as the benchmark curve of the distribution line; Compare the line loss fluctuations between various curves and the benchmark curve, and quantify the line loss change rate; The line loss estimation result is obtained based on the line loss change rate in the corresponding situation.

2. The method for calculating the theoretical line loss of a distribution network based on a typical equivalent load distribution curve according to claim 1, Its characteristic is that include: Extracting the benchmark equivalent load distribution curve and its benchmark curve of each distribution line to form an equivalent load distribution curve set of the distribution network; By comparing the equivalent load distribution curve at a certain moment with the equivalent load distribution curve set, the line loss of each line is estimated.

3. The method for calculating the theoretical line loss of a distribution network based on a typical equivalent load distribution curve according to claim 1, Its characteristics are: When establishing an equivalent load distribution curve for describing load distribution, the electrical equivalent load distribution curve is extracted according to the distribution system structure diagram and the load parameters of the specific load points.

4. The method for calculating the theoretical line loss of a distribution network based on a typical equivalent load distribution curve according to claim 1, Its characteristics are: The formula for converting the physical distance of a line in the power distribution system into electrical distance is as follows: Among them, ,but is the electrical equivalent length of line section a, is the resistance per unit length of line section a, is the physical length of line segment a; That is, the electrical length of a section of the line is: 。 5. The method for calculating the theoretical line loss of a distribution network based on a typical equivalent load distribution curve according to claim 1, Its characteristics are: When clustering the electrical equivalent load distribution curves, the slope of the electrical equivalent load distribution curve between every two equivalent load points is used as a clustering feature to cluster the electrical equivalent load distribution curves.

6. The method for calculating the theoretical line loss of a distribution network based on a typical equivalent load distribution curve according to claim 1, Its characteristics are: Compare the line loss fluctuations between various curves and the benchmark curve, and quantify the line loss change rate. The specific method is as follows: Compare all types of equivalent load distribution curves except the benchmark curve with the benchmark curve, calculate the deviation of line loss under each type of curve and the line loss under the benchmark curve, and express it in percentage.

7. Distribution network theoretical line loss calculation system based on typical equivalent load distribution curve, Its characteristics are: include: The equivalent load distribution curve establishing module is configured to: establish an equivalent load distribution curve for describing load distribution; The steps for forming the equivalent load distribution curve are: Preprocess the historical data of the power distribution system to obtain the data of each distribution line; Convert the physical distance of a line in the power distribution system into electrical distance; Taking the electrical distance length as the horizontal axis, the load capacity of each load point on the line is evenly distributed; Select a point with equal electrical distance as a new equivalent load point, and add up the load capacities on the equivalent load point to obtain the load capacity on the equivalent load point; Using the load capacity value at the equivalent load point as the corresponding ordinate value, the values ​​of each equivalent load point are connected to form an electrical equivalent load distribution curve; The clustering module is configured to: cluster the electrical equivalent load distribution curves established based on the data of the same distribution line at different times; The reference curve determination module is configured to: use the equivalent load distribution curve of the largest number obtained by clustering as the reference classification of the distribution line, and use the cluster center as the reference curve of the distribution line; The line loss change rate quantification module is configured to: compare the line loss fluctuations between various curves and the reference curve, and quantify the line loss change rate; The line loss estimation module is configured to obtain a line loss estimation result according to a line loss change rate under corresponding circumstances.

8. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, Its characteristics are: When the processor executes the program, the steps of the method described in any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, Its characteristics are: When the program is executed by a processor, the steps of the method described in any one of claims 1 to 6 are performed.

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