CN103559553B - Distributing line planning and distribution transform site selection optimizing method based on load moment theory - Google Patents

Abstract

Distribution line planning and distribution transformer site selection optimization method based on load moment theory. The purpose of the present invention is to provide detection and analysis for line transformation, such as line diameter change or load cutover, by calculating the load moment of the line load when the actual or future load of the line is known when the power line is reconstructed or newly added. , to provide optimal load point layout calculation and line specification selection for new planning. In order to solve the above technical problems, the present invention is realized through the following technical solutions: a distribution line detection and power supply layout method, which takes county-level power supply enterprises as the planning object, calculates the line health degree and divides the distribution line through the power grid model. Compared with the prior art, the present invention has the advantages of: using the current power grid model, through the calculation of the load moment, load shunting is performed on lines with poor health, with as few changes as possible and under the best economical design Design power lines or transform old lines.

Description

Distribution Line Planning and Distribution Transformer Site Selection Optimization Method Based on Load Moment Theory

technical field

The invention relates to the field of power systems, in particular to a method for distribution line planning and distribution transformer site selection optimization based on load moment theory.

Background technique

At present, due to the relatively weak power foundation and planning within the jurisdiction of county-level power supply enterprises, the weak power supply capacity is still the most prominent problem. There are two reasons for this situation: First, the large jurisdiction A line has many load terminals, large line losses, and low voltage causes insufficient power supply capacity on the entire line; second, the peak and valley times of the line terminal power load load are obvious and concentrated, and the line and substation capacity is limited and the layout is difficult to adjust in time In some cases, overloading causes failure and damage of power distribution equipment, and power outages are common. For this, we need to optimize the line. In the current power network planning, the schemes with good economic indicators are often manually selected according to the size and location of the power load and the relative distance from the power supply. But such involvement often adds too many subjective factors.

Further, the invention patent "An RFID-based Power Transmission and Distribution Line Equipment Management System and Its Management Method" with the application number "CN201110381625.3" has disclosed a relatively advanced power distribution line planning method. Belonging to the field of electric power systems, it provides an RFID-based power transmission and distribution line equipment management system and its management method, using low-cost radio frequency ID cards as identification symbols for power transmission and distribution line equipment, which is small in size, light in weight, and corrosion-resistant , Long service life, the mobile handheld terminal has GPS function, which makes it more accurate and convenient to read the code of the radio frequency ID card, and can input various working condition descriptions on site, and relevant information data can be stored through the memory module. After using this device to take pictures , transmit the line data with ID information to the data server for permanent storage, realize effective management and recording of line equipment and various state-owned properties, reduce management costs, effectively manage and plan state-owned assets, and avoid duplication The occurrence of secondary investment and equipment loss of maintenance.

However, such equipment costs a lot, and the maintenance cost is also very high, so it is difficult to popularize.

In order to effectively improve the supply quality of the vast counties and ensure the scientificity of various transformations of county-level power distribution, we need a more economical and effective wiring method. The optimization of power network erection is one of the important tasks of power planning. Its core is to seek the power network with the best structure.

Therefore, we need some quantifiable and measurable standards and methods to assist in the optimization of the power network erection, and to seek the power network with the best structure.

Contents of the invention

The purpose of the present invention is to provide detection and analysis for line transformation, such as line diameter change or load cutover, by calculating the load moment of the line load when the actual or future load of the line is known when the power line is reconstructed or newly added. , to provide optimal load point layout calculation and line specification selection for new planning.

In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

The distribution line planning and distribution transformer site selection optimization method based on the load moment theory, with county-level power supply enterprises as the planning object, includes the following steps:

A. Find or select the network frame or cable line to be tested, and calculate the total load moment M _t of the line;

B. By comparing with the theoretical load moment M _max of the same voltage level and the same specification line, the health status of the current line can be obtained;

C. If the total load moment M _t is greater than the theoretical load moment, but at the same voltage level, if the theoretical load moment of other specifications can meet the current line load, replace the wire with a different wire diameter;

D. If step C is not satisfied, load distribution needs to be performed on the line, and n lines in good health with a distance of less than l from the current line are obtained as alternative shuntable lines through spatial analysis;

E. Calculate the load moment ΔM of the overload load of the current line by calculating the total load moment M _t of the line and the theoretical load moment M _max , and obtain the load to be shunted on the current line through ΔM, calculate the total load moment of the shunted line after the load is shunted, and compare it with Compare the theoretical load moment of the shunt line to confirm whether the shunt line after load shunting is healthy;

F. Real-time monitoring of the health status of the diverted N lines after capacity expansion.

Preferably, in step A, the total load moment of the line is calculated. The load moment size M of the load is proportional to the distance L and the load power P of the load from the power source, and is linearly related. Therefore, the total load moment of the line is each on the line. The sum of the load moments of the load: The unit is: kilowatt * kilometer. Among them, p _i is the load power on the i-th line among the n lines; l _i is the distance between the i-th line and the original line among the n lines. The total load moment M _t can be calculated in this way.

Preferably, in step D, the algorithm for obtaining nearby lines with good health conditions: obtain the polygonal area formed by all the devices on the current line, and obtain the terminals or connection point devices on other lines within the specified distance L through space calculation. If they exist, then The line where the terminal or connection point device is located can be used as the line to be shunted.

Preferably, in step E, obtain the algorithm of the load to be shunted: obtain the load on the line that is less than L from the line to be shunted, traverse and obtain one or more loads (multiple loads) whose load moment is the closest but slightly greater than ΔM from these loads belong to one branch as much as possible), as the load to be shunted, the distance from the load to be shunted to the shunt line and the distance from the connection point to the power source are obtained through space calculation, so as to obtain the load moment of the shunted load, and the total load moment of the shunt line is the original load moment Add the load moment for the shunt load.

Preferably, it also includes the calculation of the minimum load moment of load planning for the application research of power load moment in distribution line detection and power supply layout planning, which includes the following steps in sequence:

A. Select N load points to be measured. If the types of load points are the same, it is simple type load moment calculation, otherwise it is composite type load moment measurement;

B. Calculation of the coordinates of the optimal power supply for simple type load points: set the optimal coordinates (x, y), calculate the load moment M from the coordinate point to each selected load point, and ensure that M is the smallest, that is, the best power supply with the minimum load moment can be obtained Coordinates, the optimal power supply coordinates (x, y) satisfy the following equation:

p _i is the load power on the i-th line in the n lines

C. If the selected load point includes large users and ordinary users, it is necessary to calculate the optimal power point coordinates according to the large users and ordinary users, and then calculate the optimal power point coordinates of all loads;

D. The calculation method of the optimal power point coordinates of large users and ordinary users is the same as step B, and the optimal power point coordinates (x _c , y _c ) and (x _s , y _s ) are obtained respectively, then the optimal position of the power point distribution is Two kinds of nature load measure and calculate a certain coordinate point on the straight line position of the optimal power point, and the coordinates (x, y) of the optimal power point satisfy the following equation:

$\left.\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ></span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right\}<span\; class="notranslate">\; ;</span>$

E. Calculate the load moment of each load point according to the coordinates (x, y) of the optimal power point layout, and compare it with the theoretical load moment of various lines to obtain the specification and model recommendations of candidate lines for each load point.

Further, the optional line specifications are: LJ-120, LJ-70 and LJ-50

three kinds. These three wire diameters correspond to three Mmax of 36kW*km, 26kW*km, and 20kW*km respectively.

Compared with the prior art, the present invention has the advantages of: using the current power grid model, through the calculation of the load moment, load shunting is performed on lines with poor health, with as few changes as possible and under the best economical design Design power lines or transform old lines.

detailed description

The theoretical basis of the present invention is that under a certain allowable voltage loss condition, the larger the load, the smaller the power supply radius; on the contrary, the smaller the load, the larger the power supply radius. Therefore, the relationship between the load and its power supply radius gives rise to the concept of load moment, which is the power multiplied by the distance of the load from the power source.

Load moment = P*L (unit: kW*km)

Among them: P--power L--the distance between the load and the power supply

Similar to the torque, when the current is conducted through the line, due to the difference in the material of the line itself and the thickness of the wire, the farther away from the power point, the lower the current voltage will be. Therefore, when we know the parameters such as the wire specification and model and the terminal load, we can easily get the voltage drop, as well as the maximum transmission distance and maximum output power of different wires, which provide us with the same line or branch lines. basis of reference.

Taking an overhead line with a given voltage level and total terminal load value as an example, calculate the load moment of the line, the maximum transmission distance, the voltage drop of a certain terminal on the line, and the maximum output power.

ΔU%=(R+X·tanθ)pl/(10U ² ) (1)

Among them: R--line resistance; X--line inductance value; tanθ--line power factor; U--voltage through the line; p--active power through the line; l--line length.

Since ΔU% is a calculation base, it is often taken as a unit of p=1kW and l=1km.

Therefore, it can also be written as: ΔU%=(R+X·tanθ)/(10U ² ) (2)

Calculate the corresponding terminal voltage drop according to the specific terminal as:

ΔU＝ΔU% · P _i · l _i (3)

Among them: P _i -- the load of a certain terminal on the line l _i -- the distance from a certain terminal on the line to the power point

load moment

Among them: U _o -- power supply output voltage U _t -- rated voltage λ of load terminal -- allowable deviation voltage percentage of load terminal.

The maximum conveying distance of the line:

L _max =M/P _t (5)

Among them: P _t -- the total terminal load on the line

The maximum output power to a certain terminal on the line is:

P _imax =M/l _i (6)

If the above formula is used to pre-calculate the load moment of different lines (overhead or cable) under the conditions of maximum transmission distance and maximum output power, the obtained line load moment is also the largest (M _max ), then, when we encounter the same power point In the case of multi-distributed loads, we can calculate the "total load moment" (M _t ) of these loads and compare it with the line load moment (M _max ) under this condition to determine whether the voltage loss of these loads meets its own requirements. Rated voltage drop coefficient requirements, whether it is necessary to replace the line or adjust the load network.

The calculation method of the total load moment is:

After calculating the two load moments, it can simply and accurately guide the actual work such as on-site line safety inspection and transformation.

We know that the line loss of any branch i in the power grid can be expressed as:

In the formula, L _i and ρ _i respectively represent the line length and the resistivity of the wire material, J _i =I _i /S _i represent the economic current density, U _i and Respectively represent the voltage and power factor on the branch, _Pi represents the active power through the branch.

If the power grid has m branches, the total active power loss of the whole network is:

In the long-range planning of the power network, the load can only be an approximate estimated value. Under the same voltage level, K _i can be regarded as a constant approximately and does not change with the plan. In this way, (9) becomes:

${\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}_{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; K</span>}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

The above formula shows that as long as the total load moment is the smallest, the line loss is also the smallest.

Generally, the length L _i of each branch is a known quantity. In the general case of selecting the wire section of the grid according to the economic current density, the total loss has become a linear expression of the transmission power P _i of each branch.

In addition, according to the cross-section selected by J _i , a certain transmission power P _i must correspond to a wire cross-section S _i of a certain size. In this way, the load distance represents the volume V _i of the consumed wire material on a certain scale, namely:

$\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

therefore The smallest also means that the total wire material consumption of the grid is the smallest. When the primary investment of the transmission line mainly determines the price of the wire material, the "total load moment" is the smallest, which also means that the primary investment is the smallest.

The above is the theoretical basis of the present invention. When setting up a specific area, a distribution line detection and power distribution planning method is usually adopted, and the county-level power supply enterprise is used as the planning object, including the following steps:

A. Find or select the network frame or cable line to be tested, and calculate the total load moment _Mt of the line; The load moment is the sum of the load moments of each load on n lines: Among them, p _i is the load power on the i-th line among the n lines; l _i is the distance between the i-th line and the original line among the n lines.

B. By comparing with the theoretical load moment Mmax of the line with the same voltage level and the same specification, the health status of the current line can be obtained;

C. If the total load moment Mt is greater than the theoretical load moment, but with the same voltage level, if the theoretical load moment of other specifications can meet the current line load, replace the wire with a different wire diameter; LJ-120, LJ-70 and LJ-50 three kind. These three wire diameters correspond to three Mmax of 36kW*km, 26kW*km, and 20kW*km respectively. In this case, there is no need to split the load.

D. If step C is not satisfied, load distribution needs to be performed on the line, and n lines in good health with a distance of less than l from the current line are obtained as alternative shuntable lines through spatial analysis;

E. Calculate the load moment ΔM of the overload load of the current line by calculating the total load moment Mt of the line and the theoretical load moment Mmax, and obtain the load to be shunted on the current line through ΔM, calculate the total load moment of the shunted line after the load is shunted, and compare it with the shunted line Compare the theoretical load moment of the load to confirm whether the shunt line after load shunting is healthy; obtain the loads on the line that are less than 1 away from the line to be shunted, and traverse from these loads to obtain one or more loads with the closest load moment but greater than ΔM as the waiting Divided load: the distance from the load to be shunted to the shunted line and the distance from the connection point to the power supply is obtained through space calculation, so as to obtain the load moment of the shunted load. The total load moment of the shunted line is the original load moment plus the load moment obtained by the shunt.

Load moment to be shunted = ΔM = (Mt-Mmax)

F. Real-time monitoring of the health status of the diverted N lines after capacity expansion.

Through such a method, the distribution and design of power lines can be simply carried out, which is overall simple and economical, and is especially beneficial to the reconstruction of remote areas or older lines.

The present invention also includes the measurement and calculation of the minimum load moment of the load planning for the application research of the power load moment in the distribution line detection and power distribution planning, which includes the following steps in turn:

A. Select N load points to be measured. If the types of load points are the same, it is simple type load moment calculation, otherwise it is composite type load moment measurement;

B. Calculation of the coordinates of the optimal power supply for simple type load points: set the optimal coordinates (x, y), calculate the load moment M from the coordinate point to each selected load point, and ensure that M is the smallest, that is, the best power supply with the minimum load moment can be obtained Coordinates, the optimal power supply coordinates (x, y) satisfy the following equation: p _i is the load power on the i-th line among the n lines;

C. If the selected load point includes large users and ordinary users, it is necessary to calculate the optimal power point coordinates according to the large users and ordinary users, and then calculate the optimal power point coordinates of all loads;

D. The calculation method of the optimal power point coordinates of large users and ordinary users is the same as step B, and the optimal power point coordinates (x _c , y _c ) and (x _s , y _s ) are respectively obtained, then the optimal power point layout position is Two kinds of nature load measure and calculate a certain coordinate point on the straight line position of the optimal power point, and the coordinates (x, y) of the optimal power point satisfy the following equation:

$\left.\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ></span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right\}<span\; class="notranslate">\; ;</span>$

E. Calculate the load moment of each load point according to the coordinates (x, y) of the optimal power point layout, and compare it with the theoretical load moment of various lines to obtain the specification and model recommendation of the candidate line for each load point.

The above is only a specific embodiment of the present invention, but the technical characteristics of the present invention are not limited thereto, any changes or modifications made by those skilled in the art within the field of the present invention are covered by the patent scope of the present invention among.

Claims (6)

1. The distribution line planning and distribution transformer site selection optimization method based on the load moment theory is characterized in that it includes the following steps in sequence: A. Find or select the overhead or cable line to be tested, and calculate the total load moment M _t of the line; B. By comparing with the theoretical load moment M _max of the same voltage level and the same specification line, the health status of the current line can be obtained; C. If the total load moment M _t is greater than the theoretical load moment, but with the same voltage level, the theoretical load moment of other specifications can meet the current line load, it is recommended to replace the wire diameter; D. If the voltage level is the same as in step C, if the theoretical load moment of lines of other specifications cannot meet the current line load, it is necessary to divide the load of the line, and obtain N lines in good health with a distance of less than L from the current line through spatial analysis As a divertable line, the value of L is 200-500 meters; E. Calculate the load moment ΔM of the overload load of the current line by calculating the total load moment M _t of the line and the theoretical load moment M _max , and obtain the load to be shunted on the current line through ΔM, calculate the total load moment of the shunted line after the load is shunted, and compare it with Compare the theoretical load moment of the shunt line to confirm whether the shunt line after load shunting is healthy, F. Calculate the health status of N shuntable lines after capacity expansion, and display them in a list. 2. The distribution line planning and distribution transformer location optimization method based on load moment theory as claimed in claim 1, characterized in that: in step A, the total load moment of the line is calculated, the load moment size M of the load is related to the load distance The distance L of the power supply is proportional to the load power P and has a linear relationship. Therefore, the total load moment of the line is the sum of the load moments of each load on the line: The unit is: kilowatt * kilometer. 3. The distribution line planning and distribution transformer site selection optimization method based on load moment theory as claimed in claim 1, characterized in that: in step D, the algorithm for obtaining nearby lines with good health conditions: obtaining the current line composed of all equipment In the polygonal area, through spatial calculation, the terminal or connection point device on other lines within the specified distance L is obtained. If it exists, the line where the terminal or connection point device is located can be used as the line to be shunted. 4. The distribution line planning and distribution transformer site selection optimization method based on load moment theory as claimed in claim 1, characterized in that: in step E, the load algorithm to be shunted is obtained: the distance on the obtained line from the line to be shunted is less than L From these loads, one or more loads with the closest load moment but slightly larger than ΔM are traversed to obtain one or more loads to be shunted, and the distance from the load to be shunted to the shunt line and the distance from the connection point to the power supply are obtained through space calculation, so that The load moment of the shunt load is obtained, and the total load moment of the shunt line is the original load moment plus the load moment of the shunt load. 5. The distribution line planning and distribution transformer site selection optimization method based on load moment theory as claimed in claim 1, characterized in that: it also includes the load of the application research of power load moment in distribution line detection and power supply point layout planning. Planning the minimum load moment measurement includes the following steps in sequence: A. Select N load points to be measured. If the types of load points are the same, it is simple type load moment calculation, otherwise it is composite type load moment measurement; B. Calculation of the coordinates of the best power supply for simple type load points: set the best coordinates (x, y), calculate the load moment M from the coordinate point to each selected load point, and ensure that M is the smallest, that is, the best power supply with the minimum load moment can be obtained Coordinates, the optimal power supply coordinates (x, y) satisfy the following equation: p _i is the load power on the i-th line among the n lines; C. If the selected load point includes large users and ordinary users, it is necessary to calculate the optimal power point coordinates according to the large users and ordinary users, and then calculate the optimal power point coordinates of all loads; D. The calculation method of the optimal power point coordinates of large users and ordinary users is the same as step B, and the optimal power point coordinates (x _c , y _c ) and (x _s , y _s ) are respectively obtained, then the optimal power point layout position is Two kinds of nature load measure and calculate a certain coordinate point on the straight line position of the optimal power point, and the coordinates (x, y) of the optimal power point satisfy the following equation: $\left.\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ></span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right\}<span\; class="notranslate">\; ;</span>$ E. Calculate the load moment of each load point according to the coordinates (x, y) of the optimal power point layout, and compare it with the theoretical load moment of various lines to obtain the specification and model recommendation of the candidate line for each load point. 6. The distribution line planning and distribution transformer location optimization method based on load moment theory as claimed in claim 5, characterized in that: the line specifications and models for selection are: LJ-120, LJ-70 and LJ -50 three kinds.