CN109412140B

CN109412140B - Method for improving utilization rate of 10kV distribution line

Info

Publication number: CN109412140B
Application number: CN201810268448.XA
Authority: CN
Inventors: 李振伟; 赵树军; 王晶; 赵天翊
Original assignee: State Grid Corp of China SGCC; State Grid Hebei Electric Power Co Ltd; Handan Power Supply Co of State Grid Hebei Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; State Grid Hebei Electric Power Co Ltd; Handan Power Supply Co of State Grid Hebei Electric Power Co Ltd
Priority date: 2018-03-29
Filing date: 2018-03-29
Publication date: 2022-01-07
Anticipated expiration: 2038-03-29
Also published as: CN109412140A

Abstract

The invention discloses a method for improving the utilization rate of a 10kV distribution line, which is characterized by comprising the following steps of manufacturing a load characteristic detailed table of the 10kV distribution line according to the requirements of a power distribution network plan and a user access system and by combining with the information of a power distribution network plan data system; comprehensively analyzing the load characteristics of the target user and judging whether the properties of the line connection users are similar or not; if the line installation users are similar in nature, entering the next step; if the properties of the line installation users are not similar, returning to the previous step; overlapping loads with similar line connection user properties and different load characteristics, and accessing users with different load properties with a valley filling effect to the same distribution line; drawing a power grid target grid map through space load prediction; and reconstructing a power grid 10kV distribution line diagram according to the power grid target grid diagram and the load characteristics of the target users. The utilization efficiency of the distribution line is greatly improved, the operation benefit of the power grid is improved, the economic benefit is improved, and reliable guarantee is provided for social development.

Description

Method for improving utilization rate of 10kV distribution line

Technical Field

The invention relates to the technical field of distribution lines, in particular to a method for improving the utilization rate of a 10kV distribution line.

Background

At present, the urbanization process is rapidly developed, real estate is vigorously built, and power grid construction is relatively lagged. The conventional urban transformer substation is difficult to arrange, tense in intervals, short in corridor and difficult to wire out. The distribution network is still in a high-loss low-efficiency stage, and the operation benefit of the distribution line is low.

From 2005 to 2015, the number of public lines in Handan city was increased from 143 to 301, the maximum load of public distribution network was increased from 340MW to 512MW, and the line utilization was only 19.45% by 2015. On the basis of 2015 operation data, the utilization rate of 301 public lines is analyzed one by one. The utilization rate of the circuits is not higher than 40%, and the percentage of the circuits is 69%. The utilization rate of the 12 lines is high, and the utilization rate of the lines is only 4%. Therefore, the utilization rate of the whole line of the distribution network is low, and the situation of uneven distribution is presented.

The national grid code requires that a single distribution line recommend an attachment capacity of no greater than 11 MVA. The 135 lines with the load rate lower than 20 percent in the urban area are further analyzed: this portion of the line accounted for 44.85% and had an average mounting capacity of 9.31MVA, which was higher than the overall average (8.82 MVA), but the line peak load average was 1.05MW, which was lower than the overall average (1.7 MW). As a result of recent rapid development of the real estate industry, the number of large residential cells is rapidly increasing, as analyzed from the loads on these lines. In 2006 to 2015, the population in the urban area is increased from 143 ten thousand to 148 ten thousand, the number of low-voltage households is increased from 22 to 51 ten thousand, the population in the urban area is slowly increased, the number of resident households is rapidly increased, a large number of cells are built, the survival rate is generally low, and the load is naturally increased only by years, so that the power supply load is small, and the load rate of a power supply line and the load rate of distribution transformer are low. Therefore, the mounting capacity is high, the load level is low, and the operation benefit of the power grid is low.

The attachment capacity is high, but the actual load is small. Through the utilization rate analysis of 301 lines in the city, the utilization rate of light-load lines is below 15%. The low utilization rate of the line directly leads to low operation benefit of the distribution line.

Distribution lines are built (or rebuilt) in nearly 30 years, wherein the proportion of the transformed lines in 1998 and later is 42.5%, and the proportion of the newly built lines in nearly 5 years is 32.5%. The average load rate is lower than 396.6 km of the 20% line, and only occupies 24.2% of the total length of the line.

Therefore, it is urgently needed to improve the utilization rate of the distribution lines, improve the operation benefits of the power grid, reduce the investment of the power grid and promote the development of the economic society.

Disclosure of Invention

The invention aims to provide a method for improving the utilization rate of a 10kV line, which takes the improvement of the utilization rate of a distribution line as a means, improves the operation benefit of a power grid, reduces the investment of the power grid and promotes the development of the economic society.

The invention deeply researches and researches the current situation of the distribution line operation and the current situations of contradiction between economic and social development and power grid development and the like, determines to start from improving the utilization rate of the distribution line, and establishes a specific scheme for improving the utilization rate of the distribution line according to various urban load characteristics and a detailed distribution line load characteristic table. The line utilization rate is the ratio of the loadable capacity of the line to the actual average load. By means of different types of load superposition, the reliable access of a user to a power grid is ensured, and meanwhile, the utilization efficiency of a distribution line is greatly improved, so that the operation benefit of the power grid is improved, the economic benefit of an enterprise is improved, and the reliable guarantee is provided for social development.

The purpose of the invention is realized by the following technical scheme:

a method for improving the utilization rate of a 10kV distribution line comprises the following steps:

1) according to the power distribution network planning and the user access system requirements, a load characteristic detailed table of the 10kV power distribution line is manufactured by combining power distribution network planning data system information;

2) comprehensively analyzing the load characteristics of the target user and judging whether the properties of the line connection users are similar or not; if the line installation users are similar in property, entering step 3); if the properties of the line installation users are not similar, the method is not suitable to be applied;

3) overlapping loads with similar line connection user properties and different load characteristics, and accessing users with different load properties with a valley filling effect to the same distribution line;

4) drawing a power grid target grid map through space load prediction;

5) and reconstructing a power grid 10kV distribution line diagram according to the power grid target grid diagram and the load characteristics of the target users.

In the step 2), the load characteristics of the target user comprise load property and load characteristic.

The load characteristics include load peaks and load troughs.

In the step 3), the rule of the occurrence time of peaks and valleys of load characteristic curves of different users is summarized according to the principle of improving the utilization rate of the line but not influencing the safe and stable operation of the line during superposition, and the valley filling effect of the load curves can be realized through mutual superposition; if the cell users and the office users are accessed into the same line, the line utilization rate is improved.

Specifically, in step 3), if the load characteristics of the line of the target user have a peak a and a valley a, the analyzed line with different load characteristics has a peak B and a valley B, and if the overlapping part of the peak a and the peak B is smaller than the overlapping part of the valley a and the valley B is larger than the valley a, the valley filling effect is performed, and the two lines are accessed to the same distribution line; otherwise, the same distribution line is not accessed.

Further, if the number of the peaks a is different from that of the peaks B, and the number of the troughs a is different from that of the troughs B, the condition that the overlapping parts of all the peaks a and the peaks B are smaller than the overlapping parts of all the troughs a and the troughs B, and the sum of all the troughs B is larger than that of the troughs a is met, and the same distribution line is accessed. The method can compensate the target user in the off-peak period, and can access the same line without exceeding the met conditions due to less superposition in the peak period.

The method of the invention is based on the line load characteristic analysis, and utilizes the load valley filling effect to complete the switching of the power distribution network line, thereby not only improving the satisfaction degree of the user power utilization service, realizing the win-win situation of the safe and reliable operation of the distribution network equipment and the improvement of the line operation benefit, but also stably improving the line load rate, further reducing the line loss and effectively reducing the operation and maintenance cost. In addition, users with different load properties with the 'valley filling' effect are connected to the same distribution line, a power distribution network frame is reconstructed, a network frame diagram and a distribution line load characteristic detailed table are comprehensively utilized, and the operation benefit of the power distribution network is improved.

Drawings

FIG. 1 is a graph of residential community load characteristics;

FIG. 2 is a grid target grid diagram;

FIG. 3 is a graph of daily load characteristics of two lines for an effect example;

fig. 4 is a comparison graph of the effect example scenario before and after access.

Detailed Description

The present invention will be further explained and illustrated with reference to specific embodiments, it should be noted that the following embodiments are only preferred embodiments, not all embodiments, and should not affect the scope of the present invention.

Example 1

According to the current situation that the access of the urban power grid is limited and the development of the power grid is limited, the collected detailed power distribution network data is combined, the actual load of the power distribution line is used as a guide basis, and the connecting capacity access requirement is abandoned. Through the mode of falling the distribution network, selected 5 lines in the urban area and carried out the examination point, fall the dual supply user who originally was supplied on the circuit to above-mentioned 5 line power supplies through falling the mode. Whether the utilization rate of the 10kV distribution line can be improved or not is verified through the peak meeting crossing winter period, and the safe and stable operation of a power grid is not influenced. The circuit conditions before the modification are shown in table 1.

TABLE 1 line condition table before switching

Through the verification of the large loads of the winter and the spring festival in the peak meeting in 2016 and 10-2017 and 2, 3 lines of the test have the heavy load condition, and 1 line has the full load condition. Specifically, as shown in table 2.

TABLE 2 Table of line condition after cutting

Through analysis, the lines 1-4 are all subjected to peak adding in the peak period, but the load in the valley period is not greatly improved. But the peak load of the line 5 is not obviously improved, and the reverse valley load is greatly improved.

Further analysis shows that the original loads of the lines 1-4 are basically the same as the newly accessed loads and are residential loads; the line is originally the office load and the newly accessed line is the resident load. Therefore, the difference in load characteristics directly affects the load rate and utilization rate of the distribution line. Fig. 1 is a graph of residential cell load characteristics.

According to the power distribution network planning and the user access system requirements, a power distribution network planning data collection is combined to compile a detailed distribution line load characteristic table (see table 3), and the detailed distribution line load characteristic table can embody the load connection characteristic situation of the existing power distribution network specifically due to the fact that the accuracy of the data is guaranteed.

Table 3 detailed table of load characteristics of distribution line

1) Load property survey

The load composition of the urban distribution network is complex, the load is mainly loads of residents, businesses, enterprises, public institutions and offices, and the specific gravity of other loads is relatively low. Statistical analysis is carried out on various types of installation capacities and loads of the distribution lines, and the majority of the lines with single load property is found to be 79.4%.

The line loads with the line utilization rate not higher than 10% are single-property loads, wherein the number of residential lines is the largest; the loads of business, enterprise and public offices are the main loads, and are specifically shown in table 4.

Table 4 urban distribution line load composition table

As can be seen from table 4, the line load property is single, which tends to result in a low utilization rate; when the line load property is a mixture of multiple types, the line utilization rate is high.

2) Load signature survey

The load types in cities are widely covered, and can be roughly divided into a resident type, a business type, an office type and an industrial type. Because urban industrial loads are mainly constructed temporary power supplies, the loads occupy a small proportion in distribution networks, such as medical treatment, schools and the like. The load characteristics of the residential life lighting category, the commercial category, and the office (non-residential lighting) category are investigated.

The regularity of the commercial power load along with the change of the work and rest time is strong, the load is rapidly increased after 9 o 'clock, the load is relatively stable from 11 o' clock to 20 o 'clock, and the load is rapidly dropped after 21 o' clock. In addition, as business behaviors increase business hours in holidays, the electric load of the business behaviors is one of important factors influencing holiday load characteristics. The load is influenced by summer illumination, air conditioning and power load superposition, the annual load reaches the peak value in 7-8 months, and the annual load peak-valley difference is obvious.

The electricity load of residents is matched with living habits, the noon peak and the night peak are basically presented, and the maximum load is concentrated from 19 to 22. The load density of high-rise houses is higher than that of multi-story houses and low-rise houses. The overall level of the load density of the mature cells is higher and keeps stable, the load level of the newly developed cells is low, and the late peak is more prominent. In recent years, the influence of factors such as the fact that the ownership rate of household appliances such as fans and air conditioners is increased rapidly in summer in continuous high-temperature weather, so that the peak of the domestic electricity load of residents in summer is increased rapidly, and the influence on the electricity load of regions is large.

The daily load curve of the office (non-residential lighting) type power consumption load is characterized by the trend of a 'double-peak' curve from 8 points to 12 points and from 14 points to 18 points. The load is relatively low during non-operational time. Annual power loads mainly comprise office lighting, air conditioners and the like, and the main power utilization time is concentrated in the period of 7-8 months of peak-to-peak summer.

Through investigation and analysis of the load characteristics of the main users, the occurrence time of load characteristic curves of different users, namely 'peak' and 'trough' is obvious and regular, the load characteristics of target users are comprehensively analyzed, and whether the properties of line-connected users are similar or not is judged; if the line connection users have similar properties, the load curve valley filling effect can be realized by mutual superposition, and the same distribution line is accessed. If the line users have different properties, the method is not suitable for processing.

According to various load characteristics in a city, based on the load characteristic characteristics of the load characteristics and the current line load characteristics of a power distribution network, lines capable of carrying out the 'valley filling' effect are selected for classification, the load characteristics of surrounding land blocks of the lines are referenced, and users with different load properties and the 'valley filling' effect are accessed to the same power distribution line by adopting a load characteristic superposition method.

According to a distribution line load characteristic detailed table, a geographical information power grid system diagram is combined, the power grid condition is organically combined with an actual economic and social construction project, a power grid target net rack (as shown in figure 2) is drawn through space load prediction, and power grid planning is accurately guided.

According to a planned power grid target network frame and a detailed distribution line load characteristic table, the load characteristics of all blocks in the economic practical development are combined, the load characteristic superposition effect is fully utilized, the input-output ratio of a power grid infrastructure project is improved, and the operation benefit of a power distribution network is improved.

If the load characteristics of the line of the target user have a peak A and a valley A, the analyzed line with different load characteristics has a peak B and a valley B, if the overlapping part of the peak A and the peak B is smaller than the overlapping part of the valley A and the valley B, and the valley B is larger than the valley A, performing a valley filling effect, and connecting the two lines into the same distribution line; otherwise, the same distribution line is not accessed.

And if the number of the peaks A and the number of the peaks B are different, and the number of the valleys A and the number of the valleys B are different, the condition that the overlapped parts of all the peaks A and the peaks B are smaller than the overlapped parts of all the valleys A and the valleys B, and the sum of all the valleys B is larger than the valley A is met, and the same distribution line is accessed. The method can compensate the target user in the off-peak period, and can access the same line without exceeding the met conditions due to less superposition in the peak period.

Examples of effects

Taking access of a certain large cell in Handan city as an example, the feedback information is as follows through information reporting and distribution line load characteristic detailed table:

the total area of the building in the residential area is 21 ten thousand square meters, the building height is 99.9 meters, the total number of the buildings is 12, the comprehensive volume rate is 3.0, and the shipment volume is 6000 kVA.

A large office building comprehensive group project is arranged around the project and is put into operation before a cell is newly built, power supply points are spaced at

certain stations

066 and 069, and two lines are mutually standby. The current situation of regional power supply is as follows:

a certain station 066 line has an attachment capacity of 8000kVA, and an annual load rate of the line 2015 is 58.33%.

A station 069 line has an installed capacity of 8600kVA, and the annual load rate of the line 2015 is 48.33%.

The guiding rule requires that the mutually-supplied lines of the handles meet the N-1 criterion, namely one power supply line is planned or stopped in a fault mode, and the other line can be used for supplying all loads of the project. And it is recommended that the single line attach capacity should not be greater than 11 MVA. Therefore, the two lines are not suitable to access the load of the local cell! .

However, according to the "detailed load characteristics of distribution lines", that is, table 4, the load characteristics of a

certain station

066, 069 are found by query as shown in table 5:

TABLE 5 detailed table of load characteristics of

certain stations

066, 069

The installed capacity of one

station

066, 069 totals 16600kVA, wherein the office capacity is 11100kVA accounts for 66.87%, and the commercial capacity is 5500kVA accounts for 33.13%.

The typical daily load characteristics of the two lines are shown in fig. 3, and a typical two-peak two-valley load curve is presented. Two peaks are shown at 11 and 17. It can be known from the analyzed load characteristic curve of the residential area, i.e. fig. 1, that the two valley periods of the two lines can be compensated to a certain extent, while the peak periods are less overlapped, so that the valley filling effect in the invention is satisfied, and the access can be performed.

After an access scheme is established, the cell is put into operation for nearly one year, and through full research, the comparison curve is shown in fig. 4 when the cell is accessed and compared with the original cell-free cell, after the cell is accessed, the peak load increase amplitude of two lines is not large after the cell is overlapped, but after the cell is accessed and overlapped, the whole load peak starts in advance and ends after the cell is mistakenly accessed. The overall utilization efficiency of the line is effectively improved. The original 20.6 percent of the total content of the active carbon is increased to 37.8 percent.

Based on line load characteristic analysis, the load valley filling effect is utilized to totally complete the switching of 32 distribution network lines. The satisfaction degree of the user power utilization service is improved, and the win-win situation of safe and reliable operation of the distribution network equipment and the improvement of the line operation benefit is realized.

The utilization rate of the line cut and modified according to the 'valley filling' method is statistically analyzed, the utilization rate of the line is improved to 28.37% from the original 19.45%, the equipment utilization efficiency of the running line is greatly improved, the cost reduction and the efficiency improvement of assets are realized, and the development requirements of economy and society are met.

During the 10-12 months in 2017, the method of the invention is used for optimizing the Handan urban distribution network, the investment return and the operation benefit of the power grid are greatly improved, and the accumulated saved funds in the current year exceed 7000 ten thousand yuan:

a high-voltage customer power supply scheme is formulated for 29 times, 26 new lines are reduced compared with the previous power supply scheme, the length of a construction line is reduced by 75.6 kilometers, and the investment is saved by 6900 ten thousand yuan;

the power distribution network transformation project changes the load 43, totally changes 14 routes of the line, reduces the fault tripping frequency, improves the power supply reliability, and reduces the power failure loss 200 kilowatts of electricity in comparison with the same period of the line, so as to recover 130 ten thousand yuan of electricity charge loss;

the line load rate is stably improved, the line loss is further reduced, and meanwhile, the operation and maintenance cost is effectively reduced.

The overall social cost saved, if generalized to the entire network, would be immeasurable!

Claims

1. A method for improving the utilization rate of a 10kV distribution line is characterized by comprising the following steps: which comprises the following steps:

1) according to the power distribution network planning and the user access system requirements, combining power distribution network planning data system information, and making a load characteristic detailed table of the 10kV power distribution line;

2) comprehensively analyzing the load characteristics of target users, superposing loads with similar user properties and different load characteristics on a line, and accessing users with different load properties with a valley filling effect to the same distribution line;

3) drawing a power grid target grid map through space load prediction;

4) reconstructing a power grid 10kV distribution line diagram according to the power grid target grid diagram and by combining the load characteristics of target users;

in the step 2), the load characteristics of the target user comprise load property and load characteristics;

the load characteristics include load peaks and load troughs;

in the step 2), summarizing the time regularity of the peak and valley of the load characteristic curves of different users, and realizing the load curve valley filling effect by mutual superposition;

the judgment criteria of the rule are as follows: if the line load characteristics of the target user have a peak A and a valley A, the analyzed lines with different load characteristics have a peak B and a valley B, and if the number of the peak A and the peak B is the same, and the number of the valley A and the valley B is the same, executing according to a first path; if the number of the peak A is different from that of the peak B, and the number of the valley A is different from that of the valley B, executing according to a second path;

the first path is as follows: if the overlapping part of the peak A and the peak B is smaller than the overlapping part of the valley A and the valley B is larger than the valley A, the two lines are accessed into the same distribution line; otherwise, the same distribution line is not accessed;

the second path is as follows: if the number of the peaks A and the number of the peaks B are different, and the number of the valleys A and the number of the valleys B are different, the condition that the overlapped parts of all the peaks A and the peaks B are smaller than the overlapped parts of all the valleys A and the valleys B, and the sum of all the valleys B is larger than the valley A is met, and the same distribution line is accessed; otherwise, the same distribution line is not accessed.