A low-voltage transformer area program-controlled load simulation system

Abstract

The application discloses a low-voltage area program-controlled load simulation system, which is powered by commercial power and is provided with power supply through an area transformer; a real line loss simulation load is arranged, and the load can be adjusted through software; in the system, the branch line current is amplified in proportion by the program-controlled load, and the total line is amplified in the same proportion; a 0.05-grade AC standard meter is configured, and the error of the meter is set and calibrated through software; the system can intelligently judge the real area condition through analysis of real data; the power consumption and line loss of each branch are supported to be configured, and the simulation function of different conditions is achieved; the load in the system is designed with overvoltage, overcurrent and overtemperature protection functions. The application can simulate and emulate the power consumption condition of the real area, and supports adjustment of different power consumption conditions, different line losses and different error conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of program-controlled load simulation of low-voltage transformer area, and particularly relates to a program-controlled load simulation system of low-voltage transformer area. BACKGROUND

[0002] Low-voltage transformer area is the main component in the construction of distribution network, as it is at the end of the power grid. In recent years, with the continuous acceleration of power grid construction and the continuous improvement of the requirement of people on power quality, voltage quality gradually becomes the main data for measuring power supply quality. Therefore, the power supply department gradually improves various measures for the control of voltage quality, and the voltage quality is greatly improved. How to improve the voltage quality becomes the main content of the work of distribution network. SUMMARY

[0003] The present application provides a program-controlled load simulation system of low-voltage transformer area, which can simulate and emulate the power consumption of real transformer area, support the adjustment of different power consumption, different line loss and different error conditions, and details are described below.

[0004] The program-controlled load simulation system of low-voltage transformer area is powered by commercial power and provides power through a transformer in the area. A real line loss simulation load is arranged, and the load can be adjusted through software.

[0005] The system uses program-controlled load to amplify the branch current by a certain proportion, and the total line is amplified by the same proportion. A 0.05-level AC standard meter is configured, and the error of the meter is set and calibrated through software.

[0006] The system can achieve intelligent judgment of the real transformer area through the analysis of real data, support the configuration of the power consumption and line loss of each branch, and achieve the simulation function of different conditions. The load in the system is designed with overvoltage, overcurrent and overtemperature protection functions.

[0007] The current line of the system is simulated with large electric quantity in the same ratio environment. The program-controlled load has current tracking property, and the precision level is 0.1 level.

[0008] Further, the meter can be switched to different loops through a relay to detect the voltage and current values in different loops, and then compare the error of each meter.

[0009] The technical scheme provided by the present application has the following beneficial effects:

[0010] The application comprehensively considers network topology of the transformer area, controllable characteristic value of power supply, load demand response characteristic value and load environment influence characteristic value, has comprehensiveness, small memory occupation, and the whole simulation system can simulate and simulate the power consumption condition of the real transformer area, and supports adjustment of different power consumption conditions, different line losses and different error conditions. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of a low-voltage transformer area program-controlled load simulation system. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical scheme and advantages of the application more clear, the embodiments of the application are further described in detail below.

[0013] A low-voltage transformer area program-controlled load simulation system, the system comprises the following modules:

[0014] The construction module is used for classifying the network structure and load characteristics of the transformer area according to basic electrical characteristic parameters, and constructing a low-voltage transformer area characteristic model.

[0015] The basic electrical characteristic parameters mainly include: the indicators reflecting the network structure characteristics are power supply radius, total length of low-voltage line, cross-sectional area of main line outgoing line, and the indicators reflecting the load characteristics are distribution transformer capacity, distribution transformer natural power factor, distribution transformer average load rate, annual load growth rate, etc.

[0016] (1) Power supply radius L. L refers to the farthest distance from the end of the power supply line to the distribution transformer, which is often used as an important indicator to judge whether the network structure is reasonable. The power supply radius of the low-voltage transformer area cannot be too long. If the power supply radius is too long, it is easy to increase the power supply torque, increase the network loss, increase the line loss rate, and cause the end voltage to be too low. The smaller the power supply radius, the better the operation state of the low-voltage transformer area.

[0017] The calculation formula of the optimal power supply radius of the transformer area is:

[0018]

[0019] Wherein, σ is the load density, and F is the copper-aluminum conductor cost coefficient.

[0020] (2) Cross-sectional area D of main line outgoing line. D refers to the cross-sectional area of the first line of the main line of the transformer area, which reflects the size of the line diameter of the overall line of the transformer area to some extent. The deviation D1 of the cross-sectional area of the line refers to the deviation of the ideal cross-sectional area corresponding to the average power flowing through the line in the low-voltage transformer area from the actual cross-sectional area divided by the ideal cross-sectional area. The smaller the deviation of the cross-sectional area of the line, the better the operation state of the low-voltage transformer area. If the cross-sectional area of the main line is too small, it is easy to cause high line loss rate and low end voltage.

[0021] The deviation calculation formula of the line section area is:

[0022]

[0023] D is the ideal section area of the line, and D is the actual section area of the line. S

[0024] (3) The capacity of the distribution transformer S N The capacity of the distribution transformer is related to the reactive power loss of the distribution transformer and the reactive power loss of the load.

[0025] (4) The natural power factor λ. The natural power factor refers to the power factor of the power users in the transformer area before the compensation equipment is installed. The level of the natural power factor directly affects the power loss of the transformer area.

[0026] (5) The electricity property and proportion X4 (%). The electricity property includes residential electricity, industrial electricity, non-general electricity and other electricity. The method selects residential electricity load and industrial electricity load. X4 is the ratio of the electricity consumption of a specific electricity property to the power supply, the proportion of residential electricity is the ratio of the electricity consumption of the residents to the power supply, and the proportion of industrial electricity is the ratio of the electricity consumption of the industry to the power supply.

[0027] (6) The comprehensive line loss rate P: refers to the ratio of the line loss of the low-voltage transformer area to the total power supply of the transformer area, and is used to reflect whether the low-voltage distribution network transformer area is running economically. The smaller the comprehensive line loss rate, the better the running state of the low-voltage distribution network transformer area. The calculation formula of the line loss rate is:

[0028]

[0029] P1 is the low-voltage transformer area power supply load, and P2 is the total electricity data of the low-voltage transformer area users.

[0030] (7) The average load rate a of the distribution transformer.

[0031] Wherein, a refers to the average load rate of the distribution transformer, which refers to the ratio of the average power of the transformer area users in a year to the rated capacity of the distribution transformer. The index reflects the average level of the load of the transformer area, and the smaller the average load rate of the distribution transformer, the better the state of the low-voltage transformer area.

[0032] In line with the idea of multi-scenario analysis, the reactive power configuration capacity calculated based on the index can reduce the probability of overcompensation and undercompensation.

[0033]

[0034] Wherein, W1 is the low-voltage distribution network transformer area power supply load in the time period T, and S is the rated capacity of the distribution transformer.

[0035] ​(8) Three-phase load unbalance degree β. It reflects the unbalance degree of load distribution in three phases. Three-phase load unbalance will increase the power loss of line and affect the safe operation of electrical equipment. The smaller the three-phase load unbalance degree is, the better.

[0036]

[0037] wherein, W A , W B , W C are the power of low-voltage area A, B and C phase in a certain period, respectively, and W av is the average power of low-voltage area in a certain period.

[0038] The characteristic description module is used for characteristic description of overhead distribution line, transformer and cable distribution line. The overhead distribution line is represented by impedance mode, and the influence of conductance and susceptance is ignored. The transformer and cable distribution line are represented by resistance, reactance and susceptance mode.

[0039] The acquisition module is used for considering the low-voltage area network topology and transfer capacity, introducing the distribution automation control level condition, and finally obtaining the network topology and transfer controllability characteristic value. The improved K-Means clustering algorithm is used to cluster different types of power user loads to obtain typical characteristic users.

[0040] The typical characteristic user is specifically obtained as follows:

[0041] (1) Initialization process is performed to determine the number of categories and initial clustering center points. The optimal value is selected by calculating the total silhouette coefficient of clustering results.

[0042] (2) Feature user clustering analysis: the distance between a plurality of samples and initial center points is randomly extracted, the samples are distributed to the nearest center points according to the distance size, and k clusters are formed.

[0043] (3) Solution of clustering center points: the samples are sorted in ascending order according to the values, the samples are divided into k-1 categories, and the center sample of each category is selected as the initial clustering center of the category.

[0044] (4) Convergence criterion: if the type distance is less than a positive fraction, it converges; otherwise, it does not converge.

[0045] The solving module is used for solving the load demand response characteristic value by considering the load characteristics of the economic influence on the transformer area load, including the proportion of the load under the peak-valley flat electricity price environment, the price incentive sensitivity (based on the price or incentive of demand side management), the important load type (primary load), and the load characteristics of the environmental influence on the transformer area load, including the influence of temperature, humidity and other weather, day and night, and season, and solving the load environmental influence characteristic value; the network topology and the transfer supply controllability characteristic value of the transformer area, the load demand response characteristic value, and the load environmental influence characteristic value are comprehensively considered, the transformer area portrait is obtained by using the analytic hierarchy process, and the typical transformer area is obtained.

[0046] The load characteristics of the transformer area load influenced by the economy and the environment are considered, and the Apriori algorithm is used to realize the extraction method, and the method specifically includes the following steps:

[0047] (1) Set the minimum support and the minimum confidence;

[0048] (2) The Apriori algorithm uses a candidate set. First, a candidate set is generated, and when the support degree of the candidate set is greater than or equal to the minimum support, the candidate set is a frequent item set.

[0049] (3) First, read the things in the database, calculate the support degree of each item (candidate 1 item set), and generate the candidate 2 item set from the frequent 1 item set.

[0050] (4) Scan the database to obtain the candidate 2 item set. Then, the candidate 3 item set is obtained through the frequent 2 item set.

[0051] (5) Repeat the scanning of the database, and the method is the same as above, until no new candidate set is generated. That is, the cycle starts from the 2 item set and generates the k frequent set from the frequent (k-1) item set. When the cycle is in the k item set and only one item set is generated, the cycle is ended.

[0052] The line loss rate refers to the proportion of the loss power and the power supply of the power grid, and the statistical line loss rate and the theoretical line loss rate are included.

[0053] The establishment of the transformer area characteristic index system includes:

[0054] (1) The electrical characteristic parameters are mainly researched from power supply, transmission and power distribution and the like. In the transmission aspect, the line loss and the structure of distribution network are mainly considered: there are many factors influencing the line loss of low-voltage transformer area, mainly including the distribution network structure, equipment state and management level and the like. The power supply radius, load distribution level, power supply mode and the like reflect the distribution network structure; the transformer performance, line type, total length of low-voltage line and the like reflect the equipment state. The management level of transformer area in different regions is quite different, the management loss is the unknown loss, and there is no exact physical factor. Considering the importance degree of the indexes to the line loss of transformer area and the difficulty degree of acquisition, the main electrical characteristic parameters related to the network structure and load of transformer area are screened out.

[0055] The main electrical characteristic parameters include the power supply radius X1 (m), the total length of low-voltage line X2 (m), the load rate X3 (%), the electric property and proportion X4 (%) and the line loss rate X5 (%) and the like.

[0056] The application provides a typical low-voltage transformer area program-controlled load simulation system platform overall architecture. The system control is based on the data model of the simulation system, the power grid simulator, the electric energy meter, the line loss and the load of the system are controlled through the serial port server, so that the intelligent simulation function is realized. The algorithm verification is based on the present power grid data and the system simulation data, so as to provide the basic data source and the result verification way for the operation error algorithm verification.

[0057] The whole simulation system can simulate and simulate the power consumption condition of the real transformer area, supports the adjustment of different power consumption conditions, different line losses and different error conditions. The specific functions are as follows:

[0058] 1) Real power grid simulation

[0059] The whole system is powered by the commercial power supply, and the transformer area transformer provides power supply for the whole system.

[0060] 2) Real line loss simulation

[0061] The system is provided with a real line loss simulation load, which can simulate the real load condition in the power grid, and the load can be adjusted through the system software

[0062] 3) Electric meter large current simulation

[0063] The system adopts the program-controlled load to amplify the branch current by a certain proportion, and the total line is amplified by the same proportion. The current line of the whole system is simulated in the same proportion environment. The program-controlled load has current tracking property, and the precision level is 0.1 level.

[0064] 4) Electric meter electric energy error detection and setting

[0065] The system is configured with a 0.05 level AC standard meter, in addition, the electric meter can be switched to different electric meter loops through a relay, so as to detect the voltage and current values in different loops, and then realize the comparison of the error of each electric meter.

[0066] In addition, the system can set and calibrate the electric meter error through software, for example, the electric meter error can be calibrated according to the user's requirements, so as to achieve the purpose of simulating the deviation of the electric meter error.

[0067] 5) Detection and setting of the daily timing error of the electric meter

[0068] The system is configured with a precision time base source, in addition, the electric meter can be switched to different electric meter loops through a relay, so as to detect the time error and running time error in different loops, and then realize the comparison of the clock error of each electric meter.

[0069] In addition, the system can set and calibrate the electric meter clock error through software, for example, the electric meter clock error can be calibrated according to the user's requirements, so as to achieve the purpose of simulating the deviation of the electric meter clock error.

[0070] 6) Support for importing actual substation operation data

[0071] The system provides a function of supporting the import of real substation data, and can intelligently judge the real substation situation through analysis of the real data.

[0072] 7) Proportion configuration of each branch

[0073] The system supports the configuration of the power consumption and line loss of each branch, and can achieve the simulation function of different situations.

[0074] 8) Equipment safety protection

[0075] The system is configured with overvoltage, overcurrent and overtemperature protection functions for the load and other equipment, which effectively ensures the safety of the system.

[0076] The types of the devices in the embodiments of the application are not limited except for the special description, and the devices that can complete the above functions can be used.

[0077] Those skilled in the art can understand that the drawings are only schematic diagrams of preferred embodiments, and the above embodiment numbers are only for description, not representing the advantages and disadvantages of the embodiments.

[0078] The above description is only the preferred embodiments of the application, and does not limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A low voltage area program-controlled load simulation system, characterized in that: The system is powered by the mains electricity and provided with power by the transformer in the substation area; a real line loss simulation load is set, and the load can be adjusted by software; The system uses program-controlled loads to proportionally amplify the branch line current, and the main line is amplified by the same proportion; Equipped with a 0.05-level AC standard meter, the meter error is set and calibrated through software; The system can achieve intelligent judgment of the actual substation situation by analyzing real data; it supports the configuration of power consumption and line loss of each branch to achieve simulation functions for different situations; the loads in the system are designed with overvoltage, overcurrent and overtemperature protection functions; Among them, the construction module is used to classify the substation network structure and load characteristics based on basic electrical characteristic parameters and build a low-voltage substation characteristic model; The basic electrical characteristic parameters used mainly include: indicators reflecting grid characteristics, such as power supply radius, total length of low-voltage lines, and cross-sectional area of ​​main line outlets; indicators reflecting load characteristics, such as distribution transformer capacity, distribution transformer natural power factor, distribution transformer average load rate, and annual load growth rate; (1) Power supply radius L. The formula for calculating the optimal power supply radius of the substation is: The calculation formula for the optimal power supply radius of the substation is: Where σ is the load density and F is the cost coefficient of copper and aluminum conductors. (2) The cross-sectional area D of the main line outlet and the deviation of the line cross-sectional area are calculated as follows: Among them, D S is the ideal cross-sectional area of ​​the line, and D is the actual cross-sectional area of ​​the line; (3) Distribution transformer capacity S N , the distribution transformer capacity is related to the distribution transformer reactive loss and the load reactive loss; (4) Natural power factor λ, which refers to the power factor of the power users in the substation before the installation of compensation equipment. The level of natural power factor directly affects the power loss of the substation; (5) The nature and proportion of electricity consumption X4, where the nature of electricity consumption includes residential electricity consumption, industrial electricity consumption, non-general electricity consumption, and other electricity consumption; (6) Comprehensive line loss rate P: refers to the ratio of the power loss of the low-voltage substation line to the total power supply of the substation. The calculation formula of the line loss rate is: Among them, P1 is the power supply load of the low-voltage area, and P2 is the total power data of users in the low-voltage area; (7) Average load factor of distribution transformer a Among them, a refers to the average load rate of the distribution transformer, which refers to the ratio of the average power of users in the substation area to the rated capacity of the distribution transformer during the year. This indicator reflects the average load level of the substation area; Consistent with the concept of multi-scenario analysis, the reactive power configuration capacity calculated based on this indicator can reduce the probability of overcompensation and undercompensation; Among them, W1 is the power supply load of the low-voltage distribution network area in the time period T, and S is the rated capacity of the distribution transformer; (8) The degree of three-phase load imbalance β reflects the degree of imbalance in the distribution of load among the three phases. The three-phase load imbalance will increase the power loss of the line and affect the safe operation of the electrical equipment. The smaller the three-phase load imbalance, the better; Among them, W A 、W B 、W C are the power consumption of phases A, B, and C in the low-voltage area during a certain period, W av The average power consumption of the low-voltage area during a certain period of time; Characterization module, used to characterize overhead distribution lines, transformers, and cable distribution lines; impedance mode is used to characterize overhead distribution lines, ignoring the influence of conduction and susceptance; resistance, reactance, and susceptance mode is used to characterize transformers and cable distribution lines; The acquisition module is used to consider the low-voltage substation network topology and transfer capacity, introduce the distribution automation control level conditions, and ultimately obtain the network topology and transfer controllability characteristic values; based on the improved K-Means clustering algorithm, different types of power user loads are clustered to obtain typical characteristic users; The solution module is used to consider the load characteristics of the substation load affected by economic factors, including important load types, the proportion of loads under peak, valley and flat electricity price environments, and price incentive sensitivity, and solve the load demand response characteristic value. It also considers the load characteristics of the substation load affected by the environment, including weather such as temperature and humidity, day and night effects, and seasonal effects, and solves the load environmental impact characteristic value. It comprehensively considers the substation network topology and transfer controllability characteristic value, load demand response characteristic value, and load environmental impact characteristic value, and uses the hierarchical analysis method to profile the substation and obtain typical substations. Considering the load characteristics of the substation area affected by economic and environmental factors, the extraction method is implemented using the Apriori algorithm, which specifically includes the following steps: (1) Set the minimum support and minimum confidence; (2) The Apriori algorithm uses candidate item sets to generate candidate item sets first. When the support of a candidate item set is greater than or equal to the minimum support, the candidate item set is a frequent item set. (3) First, read the items in the database and calculate the support of each item. The candidate 2-item set is generated from the frequent 1-item set; (4) Scan the database to obtain candidate 2-item sets, and then obtain candidate 3-item sets through the obtained frequent 2-item sets; (5) Repeatedly scan the database, starting from the 2-item set and generating a k-item frequent set from the frequent k-1 item set. The loop ends when there is only one item set in the k-item set.

2. A low voltage area program-controlled load simulation system according to claim 1, characterized in that: The current circuit of the system performs large-capacity simulation under the same ratio environment; the programmable load has current tracking and an accuracy level of 0.

1.

3. A low voltage area program-controlled load simulation system according to claim 1, characterized in that: The electric meter can be switched to different circuits through relays, and the voltage and current values ​​in the different circuits can be detected, thereby realizing the comparison of the error of each electric meter.

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