1. A firefly algorithm-based offshore booster station site selection method is characterized by comprising the following steps:

step 1: inputting basic information of an offshore wind farm, including the position of a fan of the offshore wind farm and engineering constraint conditions;

step 2: randomly selecting initial positions of a plurality of offshore booster stations in an offshore wind farm according to the position of an offshore wind turbine;

and step 3: determining the rationality of the geographical position of the initial offshore booster station according to the geographical position and the environmental position;

and 4, step 4: calculating the suitable value of the position number of the offshore booster stations through an objective function, and determining the most suitable position of the offshore booster stations and the optimal distance between the offshore booster stations and an offshore wind turbine;

and 5: calculating through the optimized position formula to obtain the latest position option of the offshore booster station;

step 6: calculating the values of alpha, beta and gamma according to the optimized firefly algorithm;

and 7: the number of iterations is increased by 1;

and 8: judging whether the algorithm is converged or not, wherein the booster station is the optimal position, carrying out the next step, and returning to the step 2 without convergence;

and step 9: and comparing the site selection schemes of different booster stations, and selecting the lowest scheme of the life cycle cost as the optimal site.

2. The firefly algorithm-based offshore booster station site selection method according to claim 1, wherein the initial conditions include offshore wind farm fan position, engineering constraints, and sea cable unit price.

3. The firefly algorithm-based offshore booster station site selection method according to claim 1, wherein the optimized firefly algorithm includes the life cycle economic cost of the entire offshore booster station, and the life cycle economic cost is used as a main standard for site selection of the offshore booster station.

4. A firefly algorithm-based marine booster station site selection method as recited in claim 3, wherein the life cycle economic costs include construction investment costs, operating costs and maintenance costs.

5. The method of claim 3A firefly algorithm-based offshore booster station site selection method is characterized in that a life cycle economic cost optimal model is as follows: m is M_a+M_b+M_c；

Wherein M is_aFor investment costs, M_bFor operating costs, M_CFor maintenance costs.

6. The firefly algorithm-based offshore booster station site selection method according to claim 5, wherein M is_aCalculated by the following way:

where N is the number of offshore booster stations being built, f (M)_i) Represents the construction investment cost, M, of the ith offshore booster station_mRepresents the material cost for building an offshore booster station, J is the total number of onshore centralized control centers, mu is the investment cost of a unit length line, l_ijLength of sea cable line from booster station i to centralized control center j on land_izIs the length of the sea cable line from booster station i to wind farm z.

7. The firefly algorithm-based offshore booster station site selection method according to claim 5, wherein M is_bRespectively calculated by the following methods:

wherein, f' (M)_i) For the operating cost of the offshore booster station, lambda is the service life of the offshore booster station, M_SThe annual cost of the sea area is, and gamma is the running cost of the line with unit length.

8. The firefly algorithm-based offshore booster station site selection method according to claim 5, wherein M is_CRespectively pass throughCalculated in the following way:

M_c＝n_BM_B+n_sM_s

wherein n is_BFor the number of maintenance times of the offshore booster station, n_sFor maintenance times of sea cables, M_BFor a single maintenance charge of the offshore booster station, M_sThe single maintenance cost of the submarine cable.

Background

Wind power generation is an unavailable part of new energy, where the offshore booster station is the heart of the entire wind farm. The electrical energy generated by all wind generators is concentrated in a booster station and then connected to the land-based grid by a sea cable. Offshore booster stations are very expensive to manufacture and require nearly a decade of operation before they can be brought to profit. The reasonable site selection can reduce the cost of the whole offshore booster station and improve the operation efficiency of the whole system.

The basis of the offshore booster station site selection planning construction system is mainly an economic scheme. At present, the position of the offshore booster station is generally determined according to the overall investment of the submarine cable in the site selection stage. Since the investment cost of the submarine cable accounts for 10% of the total investment, reducing the investment cost of the submarine cable can reduce the overall investment cost. However, this approach lacks comprehensiveness and requires optimization of an economic solution.

Disclosure of Invention

The invention aims to provide a firefly algorithm-based offshore booster station site selection method aiming at one-sidedness of site selection of an offshore booster station in the prior art.

The invention is realized by adopting the following technical scheme:

a firefly algorithm-based offshore booster station site selection method comprises the following steps:

step 1: inputting basic information of an offshore wind farm, including the position of a fan of the offshore wind farm and engineering constraint conditions;

step 2: randomly selecting initial positions of a plurality of offshore booster stations in an offshore wind farm according to the position of an offshore wind turbine;

and step 3: determining the rationality of the geographical position of the initial offshore booster station according to the geographical position and the environmental position;

and 4, step 4: calculating the suitable value of the position number of the offshore booster stations through an objective function, and determining the most suitable position of the offshore booster stations and the optimal distance between the offshore booster stations and an offshore wind turbine;

and 5: calculating through the optimized position formula to obtain the latest position option of the offshore booster station;

step 6: calculating the values of alpha, beta and gamma according to the optimized firefly algorithm;

and 7: the number of iterations is increased by 1;

and 8: judging whether the algorithm is converged or not, wherein the booster station is the optimal position, carrying out the next step, and returning to the step 2 without convergence;

and step 9: and comparing the site selection schemes of different booster stations, and selecting the lowest scheme of the life cycle cost as the optimal site.

A further improvement of the invention is that the initial conditions include offshore wind farm wind turbine location, engineering constraints and sea cable unit price.

The invention has the further improvement that the optimized firefly algorithm comprises the life cycle economic cost of the whole offshore booster station, and the life cycle economic cost is used as the main standard for site selection of the offshore booster station.

A further improvement of the present invention is that the full life cycle economic costs include construction investment costs, operating costs and maintenance costs.

The further improvement of the invention is that the life cycle economic cost optimal model is as follows: m is M_a+M_b+ M_c；

Wherein M is_aFor investment costs, M_bFor operating costs, M_CFor maintenance costs.

In a further development of the invention, M_aCalculated by the following way:

where N is the number of offshore booster stations being built, f (M)_i) Represents the construction investment cost, M, of the ith offshore booster station_mRepresents the material cost for building an offshore booster station, J is the total number of onshore centralized control centers, mu is the investment cost of a unit length line, l_ijLength of sea cable line from booster station i to centralized control center j on land_izIs the length of the sea cable line from booster station i to wind farm z.

In a further development of the invention, M_bRespectively calculated by the following methods:

wherein, f' (M)_i) For the operating cost of the offshore booster station, lambda is the service life of the offshore booster station, M_SThe annual cost of the sea area is, and gamma is the running cost of the line with unit length.

In a further development of the invention, M_CRespectively calculated by the following methods:

M_c＝n_BM_B+n_sM_s

wherein n is_BFor the number of maintenance times of the offshore booster station, n_sFor maintenance times of sea cables, M_BFor a single maintenance charge of the offshore booster station, M_sThe single maintenance cost of the submarine cable.

The invention has at least the following beneficial technical effects:

the existing site selection method comprises the steps of calculating the total life cycle cost of different submarine cables by determining the positions of a wind power plant and a land transformer substation, then selecting a submarine cable scheme, calculating the installation cost of the submarine cables, and selecting the scheme with the lowest cost as the final position of a booster station. However, the existing site selection method has the defects that the mean clustering method does not consider the total cost of different coordinates of the offshore wind power plant and the difference of the prices of high and medium voltage submarine cables, and the firefly algorithm-based offshore booster station site selection method integrates the life cycle economic cost optimal model of the offshore booster station into the firefly algorithm, including the overall construction investment cost, the operation cost and the maintenance cost. And screening out the optimal offshore booster station position from more aspects. Firstly, according to the basic information of the offshore wind farm given by a user, the initial position of the offshore booster station is randomly selected according to the position of a fan of the offshore wind farm and other engineering constraint conditions, the initial position of the offshore booster station is preliminarily screened according to the offshore environment, the most suitable position of the offshore booster station and the optimal distance between the offshore booster station and the offshore fan are determined through a target function, and the optimal position of the offshore booster station is determined through a full life cycle economic cost optimal model.

Drawings

FIG. 1 is a flow chart of a firefly algorithm-based offshore booster station site selection method of the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The method comprises the following specific steps of the whole life cycle economic cost of offshore booster station site selection:

(1) full life cycle economic cost optimization model

M＝M_a+M_b+M_c

Wherein M is_aFor investment costs, M_bFor operating costs, M_CFor maintenance costs.

Investment cost M_aExpression (c):

where N is the number of offshore booster stations being built, f (M)_i) Represents the construction investment of the ith offshore booster stationCost, M_mRepresents the material cost for building an offshore booster station, J is the total number of onshore centralized control centers, mu is the investment cost of a unit length line, l_ijLength of sea cable line from booster station i to centralized control center j on land_izIs the length of the sea cable line from booster station i to wind farm z.

Running cost M_bExpression (c):

wherein, f' (M)_i) For the operating cost of the offshore booster station, lambda is the service life of the offshore booster station, M_SThe annual cost of the sea area is, and gamma is the running cost of the line with unit length.

Maintenance cost M_cExpression (c):

M_c＝n_BM_B+n_sM_s

wherein n is_BFor the number of maintenance times of the offshore booster station, n_sFor maintenance times of sea cables, M_BFor a single maintenance charge of the offshore booster station, M_sThe single maintenance cost of the submarine cable.

(2) Firefoy Algorithm Firefly Algorithm

The firefly algorithm is based on the principle of firefly luminescence, which can transmit information to its partners via light signals. In the algorithm, the fireflies are randomly distributed in the space, the content of the luciferin in each firefly is different, and when the signal is emitted, the luciferin reacts with oxygen in the air under the catalysis of the luciferase, so that the signal is transmitted by luminescence. The moving speed and direction of the fireflies are determined by their attraction force, which is determined by the relative distance between the fireflies, which is determined by their brightness. Therefore, a function is formed, the luminance of the firefly is an objective function, and other factors are determined by the luminance.

Expression of relative fluorescence brightness:

wherein, I₀Is the maximum fluorescence brightness of firefly, gamma is the light absorption coefficient, r_ijIs the distance between fireflies i, j.

Expression of attraction degree:

wherein, beta₀J (t) is the objective function value of the iterative process, 1.

The expression for the position:

x_i(n+1)＝x_i(n)+β(x_j(n)-x_i(n))+α(rand-0.5)

wherein, α is a step factor, rand is a disturbance factor, and n is the nth iteration.

(3) Optimization of firefly algorithm

The early stage searching capability of the original firefly algorithm is poor, and the later stage optimization is easy to cause disorder. An algorithm for optimizing original parameters (alpha, beta, gamma) by using a chaos theory is proposed by Chen Jun et al. The optimization algorithm mainly divides the iteration process into an initial stage and a later stage through the iteration times of the population, and different parameters are adopted at different stages. It is an improved firefly algorithm based on parameter variance adjustment.

Normalization formula:

wherein, I_iIs the individual fluorescence intensity of firefly, I_aThe average fluorescence intensity.

Expression of fluorescence intensity variance:

wherein y is the number of fireflies.

Optimizing expression of alpha, beta, gamma

Wherein alpha is_n、γ_nTo end, α₀、γ₀To begin with. Alpha is alpha_iReflecting the convergence degree of the firefly population, and the larger value indicates

Decentralization, the parameter values are close to the starting values and vice versa.

Expression of the optimized position:

x(i+1)＝x(i)+kβ_ij(x(j)-x(i))+α(rand-0.5)

wherein the content of the first and second substances,is the difference between the actual position and the ideal position.

4) Mathematical modeling

Step 1: and inputting basic information of the offshore wind power plant, including the position of a fan of the offshore wind power plant and engineering constraint conditions.

Step 2: the random firefly location represents the initial location of the booster station.

And step 3: and determining the reasonability of the booster station position according to the geography and the environment position.

And 4, step 4: and calculating the proper value of the firefly individual through the full life cycle value of the target function, and determining the brightest position of the firefly and the moving direction of the firefly.

And 5: and calculating through the optimized position formula to obtain the latest position of the firefly individual.

Step 6: and calculating the values of alpha, beta and beta according to the optimized firefly algorithm.

And 7: the number of iterations increases by 1.

And 8: and (4) judging whether the algorithm is converged, if so, judging that the booster station is the optimal position, carrying out the next step without convergence, and returning to the step (2).

And step 9: and comparing the site selection schemes of different booster stations, and selecting the lowest scheme of the life cycle cost as the optimal site.

Examples

Site selection wind power plant site (coordinates: 111.665 degree E, 111.552 degree E, 21.339 degree N, 21.377 degree N, sea related area about 48km²) The water depth of the site ranges from 23m to 27m, the distance between the center and the offshore area is about 20km, and the onshore centralized control center is positioned on the northeast side of the wind power plant. An example is to construct a 220kv offshore booster station. According to a wind power plant and a land centralized control center, 3 station site preselection schemes (table 1) of the offshore booster station are provided, wherein the preselection schemes are respectively located at the center position, the north side land near position and the northeast side land near position of the site. By exploration for the surrounding environment and the sea area, solution three is not adopted.

According to the requirement of rated ampacity, 5 choices (table 2) of the 220KV submarine cable are available. The life cycle costs of the five submarine cable solutions were first calculated when the site of the offshore booster station was built at the site center, as shown in table 3, with the life cycle cost of the 220kv submarine cable solution being the lowest. Then, the life cycle costs of the five submarine cable solutions when the site of the offshore booster station is constructed on the north side of the site are calculated, as shown in table 4, and the life cycle cost of the 220kv submarine cable solution three is the lowest.

Finally, comparing the life cycle cost of the offshore booster station site selection scheme, when the offshore booster station is built at the north position of the site, and the single-loop 3x1000mm is selected²When the submarine cable is used, the cost of the whole life cycle is the lowest, and the position is the best.

TABLE 1 offshore booster station site plan

Meter 2220 KV submarine cable scheme

TABLE 3 Total Life cycle cost of offshore booster station construction at site center location

TABLE 4 Marine Booster station construction Overall Life cycle cost at site North position

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.