High-temperature superconducting cable economical efficiency analysis method for urban power capacity increase

Abstract

The invention relates to a high-temperature superconducting cable economical efficiency analysis method for urban power capacity increase, and belongs to the field of superconducting application. The method comprises the following steps: acquiring population data, electric vehicle permeability and charging pile configuration data of an urban area, and predicting the number of public charging piles and private charging piles newly added in the urban area; predicting a newly added load peak interval according to the predicted number of the public charging piles and the predicted number of the private charging piles in combination with an automobile charging coincidence rate; designing a superconductive low-voltage capacity increasing scheme based on the newly added peak load interval; acquiring system line loss data of the superconducting low-voltage capacity increasing scheme under different load conditions; and obtaining the annual operation and maintenance cost of the superconductive low-voltage capacity-increasing scheme based on the system line loss data, and carrying out economic analysis on the superconductive low-voltage capacity-increasing scheme based on the annual operation and maintenance cost. The objective of the invention is to solve the problems of lack of systematic economic evaluation means and difficulty in accurately judging the economic applicability of the high-temperature superconducting cable under the background of urban capacity increase in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-temperature superconducting cable economic analysis method for urban power capacity expansion, and belongs to the field of superconducting applications. BACKGROUND

[0002] With the continuous advancement of urbanization and the rapid development of new energy vehicles, the urban distribution network is facing the problem of insufficient local power supply capacity. Especially in high population density areas, the large-scale deployment of charging piles significantly increases the load level of the distribution network, and the 10kV distribution transformer in some areas is close to full load operation during peak hours, and needs to be upgraded urgently. The existing distribution network capacity expansion method mainly relies on the construction of new or expanded 110kV and above voltage level substations, and the construction of high-voltage feeder lines. Although this type of scheme is mature in technology, it has problems such as large land occupation, long construction period, high investment cost, etc., and is difficult to meet the actual needs of core urban areas with limited land resources, complex construction approval, and high response time requirements for capacity expansion.

[0003] High-temperature superconducting cables have the advantages of high current density, low energy loss, and compact size, and can increase the transmission capacity of the line without increasing the voltage level, and are considered an important development direction for flexible capacity expansion of urban distribution networks. In particular, high-temperature superconducting cables with a three same-axis structure are compact in structure and flexible in layout, and are suitable for deployment in areas with limited urban underground space. Although some high-temperature superconducting cables have been used in demonstration projects, their promotion still faces the following problems: On the one hand, the overall initial investment of high-temperature superconducting systems is high, especially the cost of tapes, refrigeration equipment and cooling system operation and maintenance is significantly higher than that of conventional technology; On the other hand, there is currently a lack of system-level economic comparison methods for superconducting and conventional schemes in typical urban distribution scenarios, and it is still not possible to effectively quantify the economic critical point under different load levels and operation periods. This makes it difficult for relevant units to make a clear decision on whether to use high-temperature superconducting technology, which restricts the industrialization process. Therefore, how to design a systematic economic analysis method for urban distribution network capacity expansion scenarios, which can comprehensively consider cable structure parameters, operating load conditions, investment and operation and maintenance costs, and compare the economic adaptability of high-temperature superconducting cables and conventional schemes in different scenarios, to provide quantitative decision-making basis for urban power grid planning and technology selection, is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0004] The purpose of the present application is to provide a high-temperature superconducting cable economic analysis method for urban power capacity expansion, aiming to solve the problem of lack of systematic economic evaluation means in the prior art and difficulty in accurately judging the economic applicability of high-temperature superconducting cables in the context of urban capacity expansion.

[0005] The technical problem of the present application is solved by the following technical scheme: a high-temperature superconducting cable economy analysis method for urban power capacity expansion, comprising the following steps:

[0006] S110: Obtain population data, electric vehicle penetration rate and charging pile configuration data of the urban area, and predict the number of newly added public charging piles and private charging piles in the urban area;

[0007] S120: According to the predicted number of public charging piles and private charging piles, and in combination with the automobile charging simultaneous rate, the newly added peak load interval is predicted;

[0008] S130: Design a superconducting low-voltage capacity expansion scheme based on the newly added peak load interval;

[0009] S140: Obtain system line loss data of the superconducting low-voltage capacity expansion scheme under different load conditions;

[0010] S150: Obtain the annual operation and maintenance cost of the superconducting low-voltage capacity expansion scheme based on the system line loss data, and perform economic analysis on the superconducting low-voltage capacity expansion scheme based on the annual operation and maintenance cost.

[0011] Optionally, the population data of the urban area includes the total number of people in the urban area and the number of people in a family, and the charging pile configuration data includes a private charging pile proportion coefficient and a public charging pile proportion coefficient, and the expression for predicting the number of newly added public charging piles and private charging piles in the urban area is:

[0012]

[0013]

[0014] wherein N 公桩 is the number of public charging piles, N 私桩 is the number of private charging piles, P 城市区域 is the total number of people in the urban area, P 家庭 is the number of people in a family, K 渗透 is the electric vehicle penetration rate, K 私 is the private charging pile proportion coefficient, and K 公 is the public charging pile proportion coefficient.

[0015] Optionally, the upper and lower limits of the newly added load peak interval are obtained according to the minimum automobile charging simultaneous rate and the maximum automobile charging simultaneous rate, respectively, and the expression of the newly added load is:

[0016]

[0017] wherein P 新增负荷 is the size of the newly added load, P 私桩 is the power of the private charging pile, and P公桩 N is the number of public charging piles 公桩 N is the number of public charging piles 私桩 K is the number of private charging piles 充电同时率 is the charging simultaneity rate.

[0018] Optionally, the superconducting low-voltage capacity expansion scheme is based on a newly added peak load interval, and a three-same-axis high-temperature superconducting cable is used to connect a newly built switching station and an original transformer substation.

[0019] Optionally, the economic analysis of the superconducting low-voltage capacity expansion scheme based on the annual operation and maintenance cost adopts a net present value method, including:

[0020] The total cost is obtained by adding the annual operation and maintenance cost and the known initial investment cost, and then combined with the annual income, the net present value of the superconducting low-voltage capacity expansion scheme within a set operation period is calculated, and the net present value is obtained based on the net present value of the total cash flow. The greater the net present value, the better the economy of the superconducting low-voltage capacity expansion scheme.

[0021] The present application has the following beneficial effects:

[0022] Compared with the existing scheme, the present application realizes the life cycle economy comparison of the high-temperature superconducting cable and the conventional scheme through a unified modeling process and simulation path, and provides quantitative decision basis for the technology selection of urban power grid in the scene of land shortage and rapid load growth. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0024] Figure 1 Fig. 1 is a flowchart of a high-temperature superconducting cable economy analysis method for urban power capacity expansion according to the present application;

[0025] Figure 2 Fig. 3 is a flowchart of predicting a newly added peak load interval according to an embodiment of the present application;

[0026] Figure 3 Fig. 4 is a simple ring network structure diagram according to an embodiment of the present application;

[0027] Figure 4 Fig. 5 is a power distribution network topology structure diagram of a superconducting low-voltage capacity expansion scheme according to an embodiment of the present application;

[0028] Figure 5The figure shows the operation cost of the superconducting low-voltage capacity increasing scheme in different capacity increasing loads. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0030] Embodiment 1: The present application proposes an economic analysis method for urban power capacity increasing of high-temperature superconducting cables, and constructs a complete economic analysis process for quantitatively analyzing the economic applicability of the superconducting low-voltage capacity increasing scheme in a typical urban scenario. For the purpose of clearly describing the implementation process of the method of the present application, please refer to Figure 1 In the embodiment, the steps S110 to S150 are specifically included.

[0031] Step S110: Obtain the population data, electric vehicle penetration rate and charging pile configuration data of the urban area, and predict the number of newly added public charging piles and private charging piles in the urban area;

[0032] Optionally, the population data of the urban area includes the total number of people in the urban area and the number of family members, and the charging pile configuration data includes a private charging pile proportion coefficient and a public charging pile proportion coefficient.

[0033] Specifically, in combination with the configuration of existing public and private charging piles, the relationship between electric vehicle penetration rate and charging pile ratio is analyzed, and further in combination with the regional residential family structure, the total amount of charging piles required to be configured is calculated, and the expression is as follows:

[0034]

[0035]

[0036] Wherein N 公桩 is the number of public charging piles, N 私桩 is the number of private charging piles, P 城市区域 is the total number of people in the urban area, P 家庭 is the number of family members, K 渗透 is the electric vehicle penetration rate, K 私 is the private charging pile proportion coefficient, and K 公 is the public charging pile proportion coefficient.

[0037] Optionally, in some specific implementations, assuming an electric vehicle penetration rate of 30%, an overall vehicle-to-charging-pile ratio of 2.5:1 for public charging piles to private charging piles, and using 4 people / household and 5 people / household as two family structures, the following calculations can be performed:

[0038] When estimated at 4 people per household, the number of private charging piles and public charging piles is approximately 857 and 2143 respectively, totaling 3000.

[0039] When estimated based on 5 people per household, the numbers are 686 and 1714 respectively, totaling 2400 units.

[0040] Step S120: Predict the peak range of new load based on the predicted number of public and private charging piles and the simultaneous charging rate of vehicles.

[0041] Optionally, such as Figure 2 The flowchart shown is a process for obtaining the peak load range based on the number of public and private charging piles in this embodiment. The flowchart calculates the load contribution value of various charging facilities under typical usage scenarios based on the rated parameters and power-on simultaneity rate of different types of charging piles.

[0042] Specifically, the total power is obtained by multiplying the number of public and private charging piles by the power of each charging pile. However, since not all charging piles are charging simultaneously, this embodiment also considers the issue of vehicle charging simultaneity, resulting in the expression for the additional load:

[0043]

[0044] Where P 新增负荷 P represents the size of the new load. 私桩 For private charging pile power, P 公桩 For the power of public charging stations, N 公桩 N represents the number of public charging stations. 私桩 For the number of private charging stations, K 充电同时率 This refers to the charging simultaneous rate.

[0045] Optionally, this embodiment refers to the current mainstream configuration of 7 kW for private charging piles and 20 kW for public charging piles, and comprehensively considers the different charging simultaneity rates of various types of piles in actual operation. This embodiment takes 0.5 as the minimum charging simultaneity rate and 0.7 as the maximum charging simultaneity rate. It can be estimated that the peak range of new load in urban areas is 19.6–34.2 MW, which can be used to provide quantitative support for the capacity configuration and technology selection of subsequent capacity expansion schemes.

[0046] S130: Design a superconducting low-voltage capacity expansion scheme based on the newly added peak load range;

[0047] Optionally, unlike the traditional method of analyzing the investment return of the cable as an isolated component, the embodiment first takes the system loss change caused by the cable into the evaluation index in the urban power grid capacity expansion scenario, and conducts economic analysis. The embodiment designs a simple ring network structure for analysis, as shown in Figure 3 The red area in the figure shows the newly added load caused by the increase of charging piles. In order to supply power to this area, according to the industry-known N-1 principle, the embodiment selects one 10kV high-temperature superconducting cable from each of bus 2 and bus 10 (two 10kV substations), and the design capacity of the superconducting cable needs to meet the newly added peak load of 34.2MW. Therefore, according to the industry-known method, a superconducting low-voltage capacity expansion scheme is designed, which is to set up a 10kV switch station in the original load area, and connect it to the adjacent substation with capacity margin through three high-temperature superconducting cables with the same axis structure to form a low-voltage flexible capacity expansion channel. The system structure is shown in Figure 4 .

[0048] S140: Obtain system line loss data of the superconducting low-voltage capacity expansion scheme under different load conditions.

[0049] Optionally, in some specific embodiments, the electromagnetic simulation software is used to obtain the system line loss data of the superconducting low-voltage capacity expansion scheme under different load conditions.

[0050] Further, since there is no ready-made component model of the three same axis high-temperature superconducting cable in the existing electromagnetic simulation software, the embodiment first determines the equivalent electrical parameters of the cable according to the structural parameters, and constructs the equivalent circuit model based on the coupling relationship of the three same axis cable. The key parameters such as self-inductance, capacitance and mutual inductance of the cable can be obtained by structural analysis method, and are used to establish the simulation model of the three same axis high-temperature superconducting cable. The design parameters used are shown in Table 1.

[0051] Table 1: Parameter table of three same axis superconducting cable

[0052]

[0053] Further, after the design parameters are determined, the self-inductance, mutual inductance and ground capacitance of each phase can be determined by the following formula. Specifically, the electrical equivalent parameters of the cable are obtained based on electromagnetic field theory, wherein the self-inductance and mutual inductance are calculated by the conductor arrangement radius, winding angle and insulation dielectric constant, and the ground capacitance is calculated by combining the relative dielectric constant and geometric size. The self-inductance, mutual inductance and ground capacitance of each phase are the core input of the equivalent circuit model, which is used to construct the high-temperature superconducting cable component model with three-phase coupling structure, and then embedded in the simulation software for power flow calculation.

[0054]

[0055]

[0056]

[0057] wherein, is the self-inductance of each phase, is the mutual inductance between phases M, is the capacitance to ground, μ0 represents the vacuum permeability; ε0 represents the vacuum permittivity; ε r represents the relative dielectric constant of the insulating material; tanα i and tanα j represents the winding angle; r i and r j represents the radius; r s represents the radius of the shielding layer; a i and a j represents the winding direction, taking +1 or -1.

[0058] Optionally, considering that the obtained capacity expansion demand is distributed in a wide load interval, in order to obtain the system line loss variation characteristics of the two schemes under different load levels, the embodiment adopts a discrete sampling strategy for segmented simulation analysis. The predicted capacity expansion load interval in the design is 19.6-34.2 MW, the sampling interval P is set to [20.0, 35.0] MW, the step ΔP is 5.0 MW, and four typical load points are set for simulation calculation. Under each sampling point, the power distribution network model of the superconducting low-voltage capacity expansion scheme is subjected to power flow simulation, the system branch active loss data is extracted and summed up, and the corresponding bus line loss is obtained. The simulation results under different load conditions are shown in Table 2.

[0059] Table 2: Tie line loss table of superconducting low-voltage capacity expansion scheme

[0060]

[0061] S150: Obtain the annual operation and maintenance cost of the superconducting low-voltage capacity expansion scheme based on the system line loss data, and perform economic analysis on the superconducting low-voltage capacity expansion scheme based on the annual operation and maintenance cost.

[0062] Optionally, based on the system line loss data, the annual operation and maintenance cost (OPEX) is obtained, and then the known initial investment cost (CAPEX) and the annual operation and maintenance cost are used to comprehensively reflect the cost composition and expenditure difference of different schemes in the long-term operation cycle.

[0063] Specifically, the initial investment cost CAPEX includes the purchase and installation expenses of main equipment, including the construction cost of a new 10 kV switch station, three same-axis high-temperature superconducting cables, refrigeration equipment and supporting infrastructure in the superconducting low-voltage capacity expansion scheme. The equipment price and installation cost are referred to the public quotation and industry estimation of the same type of project.

[0064] The annual operation and maintenance cost OPEX mainly includes three parts: ① the electricity fee expenditure generated by the line active loss; ② the system self-power consumption, including the cooling system operation power consumption (such as the annual average power consumption) in the superconducting low-voltage capacity expansion scheme; and ③ the annual maintenance and equipment inspection cost, which is estimated according to the fixed proportion according to the system complexity. Among them, the line loss data is derived from the simulation results at different load points in S140, and can be converted into annual operation energy consumption expenditure combined with the set electricity price.

[0065] In addition, the OPEX part introduces an operation load factor to adjust the annual average power consumption level to simulate the non-full load operation state of the equipment. The above CAPEX and OPEX items are respectively time accumulated and discounted in the entire life cycle, and the calculated cost is as shown in Figure 5

[0066] Optionally, in the present embodiment, the economic analysis of the superconducting low-voltage capacity expansion scheme is carried out by using the net present value (NPV) method. It should be understood that the NPV is used to evaluate the cumulative cash flow present value of a scheme within a given period to judge its investment return ability and economic applicability. In the specific calculation, the NPV value is obtained by discounting the annual net cash flow at a set discount rate, and the calculation formula is as follows:

[0067]

[0068] In the formula, C t is the net cash flow of the project in the t year; C0 is the initial investment cost (CAPEX); r is the discount rate; and n is the service life of the project.

[0069] Optionally, in some specific embodiments, the service life of the system is set to 40 years, the discount rate is set to 8%, the load factor is set to 0.35, and the electricity price is set to 0.7 yuan / kWh. The annual net cash flow is composed of the difference between the electricity fee income and the annual operation expenditure, wherein the income part is calculated according to the unit electricity price and the power supply capacity, and the operation expenditure mainly includes the line energy consumption, the system self-power consumption and the maintenance cost. The annual NPV of each scheme is calculated, and the change trend thereof with the operation life is further compared. The simulation analysis result shows that under the 20.0 MW load, the NPV of the superconducting scheme is significantly improved after the 17th year; under the 35.0 MW load, the NPV is significantly improved after the 14th year, and the economic return advantage is intensified with the increase of the load.

[0070] ​The specific embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. An economic analysis method for high-temperature superconducting cables for urban power capacity expansion, characterized in that, The method includes the following steps: S110: Obtain population data, electric vehicle penetration rate and charging pile configuration data for urban areas, and predict the number of new public and private charging piles in urban areas. S120: Predict the peak range of new load based on the predicted number of public and private charging piles and the simultaneous charging rate of vehicles. S130: Design a superconducting low-voltage capacity expansion scheme based on the newly added peak load range; S140: Obtain system line loss data of the superconducting low-voltage capacity expansion scheme under different load conditions; S150: Based on the system line loss data, obtain the annual operation and maintenance cost of the superconducting low-voltage capacity expansion scheme, and perform an economic analysis of the superconducting low-voltage capacity expansion scheme based on the annual operation and maintenance cost.

2. The economic analysis method for high-temperature superconducting cables for urban power capacity expansion as described in claim 1, characterized in that, The urban area population data includes the total urban population and household size, and the charging pile configuration data includes the proportion coefficient of private charging piles and the proportion coefficient of public charging piles. The expression for predicting the number of new public and private charging piles in the urban area is as follows: ； ； Where N 公桩 N represents the number of public charging stations. 私桩 For the number of private charging stations, P 城市区域 P represents the total population of the urban area. 家庭 For the number of family members, K 渗透 For electric vehicle penetration rate, K 私 K represents the proportion of private charging stations. 公 The percentage of public charging stations.

3. The economic analysis method for high-temperature superconducting cables for urban power capacity expansion as described in claim 1, characterized in that, The upper and lower limits of the peak range of the new load are obtained based on the minimum and maximum simultaneous charging rates of vehicles, respectively. The expression for the new load is as follows: ； Where P 新增负荷 P represents the size of the new load. 私桩 For private charging pile power, P 公桩 For the power of public charging stations, N 公桩 N represents the number of public charging stations. 私桩 For the number of private charging stations, K 充电同时率 This refers to the charging simultaneous rate.

4. The economic analysis method for high-temperature superconducting cables for urban power capacity expansion as described in claim 1, characterized in that, The superconducting low-voltage capacity expansion scheme is based on the newly added peak load range and uses three coaxial high-temperature superconducting cables to connect the newly built switch station and the existing substation.

5. The economic analysis method for high-temperature superconducting cables for urban power capacity expansion as described in claim 1, characterized in that, The economic analysis of the superconducting low-voltage capacity expansion scheme based on the annual operation and maintenance costs adopts the net present value method, including: The total cost is obtained by adding the annual operation and maintenance cost to the known initial investment cost. Then, combined with the annual revenue, the sum of the present value of net cash flow of the superconducting low-voltage capacity expansion scheme within the set operating years is calculated. The net present value is obtained based on the sum of the present value of net cash flow. The larger the net present value, the better the economic efficiency of the superconducting low-voltage capacity expansion scheme.

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