CN113723820A - Evaluation method and device for high-temperature superconducting cable access system - Google Patents

Abstract

The invention provides an evaluation method and a device of a high-temperature superconducting cable access system, wherein the method comprises the following steps: acquiring relevant parameters of the superconducting cable, and calculating technical and economic indexes according to the relevant parameters of the superconducting cable; wherein the technical and economic indicators include: power supply reliability index, transferred power quantity, short-circuit current, line loss rate and life cycle cost; grading the technical and economic indexes through a rank and ratio method to obtain an index grading interval value; and taking the interval value of the index grading as a parameter of the membership function, and grading the technical and economic index to obtain a grading value of the technical and economic index. The invention combines the classic evaluation method of power grid planning and the characteristics of a superconducting power transmission system, and can carry out grade division on indexes and carry out quantitative evaluation on the schemes to be selected no matter the comparison indexes have little difference or the schemes to be selected are more.

Description

Evaluation method and device for high temperature superconducting cable access system

technical field

The invention relates to the technical field of high-temperature superconducting cables, in particular to a method and device for evaluating a high-temperature superconducting cable access system.

Background technique

For power grid planning, the power supply reliability and investment cost of the power grid are the most important, so today's commonly used power grid evaluation mechanisms in my country are mainly related to the analysis from the two aspects of economy and safety. The comprehensive evaluation method of power grid can integrate economic indicators (life cycle cost) and technical indicators (such as power outage frequency, transferred power, etc.) to determine the final quantitative evaluation results. The common fuzzy comprehensive evaluation method and TOPSIS method.

However, both the fuzzy comprehensive evaluation method and the TOPSIS method have certain defects. The fuzzy comprehensive evaluation method often only considers the main factors and ignores the secondary factors, so that the evaluation results are not comprehensive enough, and the subjectivity of the evaluation is also obvious. However, the TOPSIS method cannot obtain accurate results when the indicators are symmetrical, and it can only sort the pros and cons of each evaluation object, and cannot manage by grades, and the sensitivity is not high. At the same time, because the high-temperature superconducting cable access system and conventional power grid access are quite different in terms of system structure, cost composition, and technical impact on the power grid, the above two methods are difficult to comprehensively evaluate the high-temperature superconducting cable access system. Apply directly.

SUMMARY OF THE INVENTION

In order to solve the above existing problems, the present invention provides an evaluation method and device for a high-temperature superconducting cable access system, which provides a reference for superconducting cable application site selection and scheme comparison.

A first aspect of the present invention provides an evaluation method for a high-temperature superconducting cable access system, including:

Obtain the relevant parameters of the superconducting cable, and calculate the technical and economic indicators according to the relevant parameters of the superconducting cable; wherein, the technical and economic indicators include: power supply reliability index, transferred power, short-circuit current, line loss rate and life cycle cost ;

The technical and economic indicators are classified by the rank sum ratio method to obtain the interval value of the index classification;

The interval value of the index bin is used as a parameter of the membership function, and the technical and economic indicators are scored to obtain the score value of the technical and economic indicators.

Further, after obtaining the score value of the technical and economic indicators, it also includes:

Select several feasible application scenarios based on reliability boundary conditions and the full life cycle cost;

A more feasible application scenario is selected from the several feasible application scenarios according to the score value of the technical and economic indicators; wherein, the higher the score value of the technical and economic indicators, the higher the feasibility of the application scenario.

Further, the calculation of technical and economic indicators according to the relevant parameters of the superconducting cable includes:

The power supply reliability index is calculated based on the relevant parameters of the failure rate of the superconducting cable; wherein, the power supply reliability index includes: the system average power outage frequency, the system average power outage duration and the system power supply reliability rate;

Calculate the transfer power of the superconducting cable access system based on the power flow results;

Calculate the short-circuit current after the superconducting cable is connected to the system based on the impedance value of the superconducting cable and the electrical simulation model;

Calculate the line loss rate of the superconducting cable added to the system based on the power supply and sales;

Based on the cost of the superconducting cable, the cost of the refrigerator, the electricity price, and the transmission capacity, the life cycle cost of the superconducting cable is calculated.

Further, the average power outage frequency of the system is calculated by the following formula:

为负荷节点g的用户数，λ_g为负荷节点g的年故障停运频率。Among them, I _SAIF is the average power failure frequency of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node g, and λ _g is the annual fault outage frequency of load node g.

Further, the average power outage duration of the system is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _SAID is the average power outage duration of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

Further, the system power supply reliability rate is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _ASA is the reliability rate of power supply of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

A second aspect of the present invention provides an evaluation device for a high-temperature superconducting cable access system, including:

The technical and economic index calculation module is used to obtain the relevant parameters of the superconducting cable, and calculate the technical and economic indicators according to the relevant parameters of the superconducting cable; wherein, the technical and economic indicators include: power supply reliability index, transferred electricity, short-circuit current, Line loss rate and life cycle cost;

The binning module is used for binning the technical and economic indicators through the rank sum ratio method to obtain the interval value of the binning of the indicators;

The scoring module is configured to use the interval value of the index classification as a parameter of the membership function, to score the technical and economic indicators, and obtain the score value of the technical and economic indicators.

Further, the described evaluation device for a high-temperature superconducting cable access system also includes:

The application scenario selection module is used to select several feasible application scenarios based on the reliability boundary conditions and the whole life cycle cost; according to the score value of the technical and economic indicators, select a higher feasible application scenario from the several feasible application scenarios Application scenario; wherein, the higher the score of the technical and economic indicators, the higher the feasibility of the application scenario.

Further, the technical and economic index calculation module is also used for:

The power supply reliability index is calculated based on the relevant parameters of the failure rate of the superconducting cable; wherein, the power supply reliability index includes: the system average power outage frequency, the system average power outage duration and the system power supply reliability rate;

Calculate the transfer power of the superconducting cable access system based on the power flow results;

Calculate the short-circuit current after the superconducting cable is connected to the system based on the impedance value of the superconducting cable and the electrical simulation model;

Calculate the line loss rate of the superconducting cable added to the system based on the power supply and sales;

Based on the cost of the superconducting cable, the cost of the refrigerator, the electricity price, and the transmission capacity, the life cycle cost of the superconducting cable is calculated.

Further, the average power outage frequency of the system is calculated by the following formula:

为负荷节点g的用户数，λ_g为负荷节点g的年故障停运频率。Among them, I _SAIF is the average power failure frequency of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node g, and λ _g is the annual fault outage frequency of load node g.

Further, the average power outage duration of the system is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _SAID is the average power outage duration of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

Further, the system power supply reliability rate is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _ASA is the reliability rate of power supply of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

Compared with the prior art, the beneficial effects of the embodiments of the present invention are:

The present invention provides an evaluation method and device for a high-temperature superconducting cable access system, wherein the method includes: acquiring relevant parameters of the superconducting cable, and calculating technical and economic indicators according to the relevant parameters of the superconducting cable; The indicators include: power supply reliability index, transferred power, short-circuit current, line loss rate and life cycle cost; the technical and economic indicators are classified by the rank sum ratio method to obtain the interval value of the index classification; The interval value of the bin is used as a parameter of the membership function, and the technical and economic indicators are scored to obtain the score value of the technical and economic indicators. The invention combines the classical evaluation method of power grid planning and the characteristics of the superconducting power transmission system. No matter when the comparison index is not very different or there are many options to be selected, the index can be classified into grades, and the options to be selected can be quantitatively evaluated to connect the superconducting cables. The power grid system provides a comprehensive evaluation method, which provides a reference for the application site selection and scheme comparison of superconducting cables, and has a positive effect on promoting the practical application of superconducting cables.

Description of drawings

In order to illustrate the technical solutions of the present invention more clearly, the following will briefly introduce the accompanying drawings used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, which are common in the art. As far as technical personnel are concerned, other drawings can also be obtained based on these drawings without any creative effort.

1 is a flow chart of a method for evaluating a high-temperature superconducting cable access system provided by an embodiment of the present invention;

2 is a flowchart of an evaluation method for a high-temperature superconducting cable access system provided by another embodiment of the present invention;

3 is a flowchart of an application of the rank sum ratio method provided by an embodiment of the present invention;

4 is a device diagram of a fuzzy converter provided by an embodiment of the present invention;

5 is a flowchart of a fuzzy comprehensive evaluation process provided by an embodiment of the present invention;

6 is a schematic diagram of a membership function of a cost index provided by an embodiment of the present invention;

7 is a schematic diagram of a membership function of a benefit index provided by an embodiment of the present invention;

8 is a schematic diagram of a comprehensive evaluation index system of a superconducting cable access system provided by an embodiment of the present invention;

9 is a flowchart of a comprehensive evaluation process of a superconducting cable access system provided by an embodiment of the present invention;

10 is a device diagram of an evaluation device for a high-temperature superconducting cable access system provided by an embodiment of the present invention;

11 is a device diagram of an evaluation device for a high-temperature superconducting cable access system provided by another embodiment of the present invention;

FIG. 12 is a structural diagram of an electronic device according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be understood that the step numbers used in the text are only for the convenience of description, and are not intended to limit the order in which the steps are performed.

It should be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly dictates otherwise.

The terms "comprising" and "comprising" indicate the presence of the described features, integers, steps, operations, elements and/or components, but do not exclude one or more other features, integers, steps, operations, elements, components and/or the existence or addition of its collection.

The term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items.

With the rapid growth of my country's economy, the increase in power consumption in large cities and the increase in power grid load density, the power grid transmission capacity is close to saturation and the problem of cable aging is serious. Therefore, it is necessary to adopt a higher transmission capacity transmission method to solve the problem of power transmission. Channel tension and other issues.

Since the discovery of superconducting ceramic oxides in 1986, the operating temperature of superconducting cables has been raised to the liquid nitrogen temperature region. The relatively cheap liquid nitrogen has greatly reduced the cooling and operating costs of superconducting power transmission systems. Over the past few decades, superconducting material technology has achieved rapid development, and the gradual maturity and commercialization of superconducting wires has laid the foundation for the research and development and application of superconducting power transmission technology. As various countries have successively built a number of demonstration projects for the application of superconducting cables, the research on the large-scale application of superconducting power transmission systems has also received more and more attention.

As one of the advanced power grid technologies, superconducting power transmission technology uses the high current-carrying density and unimpeded current-carrying capacity of superconducting materials in the superconducting state to replace conventional metal materials such as copper and aluminum as current-carrying conductors to achieve high-density power transmission. . Compared with conventional cable transmission technology, superconducting cable transmission technology has the characteristics of low loss, large capacity, corridor saving, environmental friendliness, and optimized power grid structure, and has great potential for development. Considering that the transmission capacity characteristics, short-circuit current characteristics and quench behavior of superconducting cables are quite different from those of conventional cables, it is necessary to conduct a comprehensive analysis of the comprehensive technical and economic characteristics of superconducting cables to obtain their applicable scenarios and more Promote the application and development of superconducting power technology.

The comprehensive evaluation method is to use a certain method according to the given conditions for the whole evaluation object, and assign an evaluation value to each evaluation object, and then select the best or rank according to this. In the field of power grid planning, the purpose of comprehensive evaluation is to quantify the power grid in terms of economy and safety, so that the power grid planning can meet the requirements of power development, so that the economical investment is in line with the benefits generated.

Therefore, based on the characteristics of high-temperature superconducting cables, this paper will extract the technical, economic and economic evaluation indicators of superconducting cable access systems, and refer to the classic evaluation methods to propose a comprehensive evaluation method suitable for high-temperature superconducting cable access systems.

first.

Referring to FIGS. 1-2, an embodiment of the present invention provides an evaluation method for a high-temperature superconducting cable access system, including:

S10. Obtain relevant parameters of the superconducting cable, and calculate technical and economic indicators according to the relevant parameters of the superconducting cable; wherein, the technical and economic indicators include: power supply reliability index, transferred power, short-circuit current, line loss rate and full life cycle cost.

In a specific embodiment, the calculation of technical and economic indicators according to the relevant parameters of the superconducting cable includes:

The power supply reliability index is calculated based on the relevant parameters of the failure rate of the superconducting cable; wherein, the power supply reliability index includes: the system average power failure frequency, the system average power failure duration and the system power supply reliability rate.

Specifically, the average power outage frequency of the system is calculated by the following formula:

为负荷节点g的用户数，λ_g为负荷节点g的年故障停运频率。Among them, I _SAIF is the average power failure frequency of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node g, and λ _g is the annual fault outage frequency of load node g.

The average power outage duration of the system is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _SAID is the average power outage duration of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

The system power supply reliability rate is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _ASA is the reliability rate of power supply of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

Calculate the transfer power of the superconducting cable access system based on the power flow results.

Based on the impedance value of the superconducting cable and the electrical simulation model, the short-circuit current after the superconducting cable is connected to the system is calculated.

Calculate the line loss rate of the superconducting cable added to the system based on the power supply and sales.

Based on the cost of the superconducting cable, the cost of the refrigerator, the electricity price, and the transmission capacity, the life cycle cost of the superconducting cable is calculated.

S20, classifying the technical and economic indicators by a rank sum ratio method to obtain an interval value of the index classification.

S30. Use the interval value of the index classification as a parameter of the membership function, and score the technical and economic index to obtain the score value of the technical and economic index.

In a specific implementation manner, the step S30 further includes:

S40. Select several feasible application scenarios based on the reliability boundary condition and the whole life cycle cost.

S50. Select an application scenario with higher feasibility from the several feasible application scenarios according to the score value of the technical and economic indicators; wherein, the higher the score value of the technical and economic indicators, the higher the feasibility of the application scenario.

The invention provides an evaluation method for a high-temperature superconducting cable access system, which combines the classical evaluation method of power grid planning and the characteristics of a superconducting power transmission system, and can rank the indicators regardless of the difference in the comparison indicators or when there are many options to choose from. It provides a comprehensive evaluation method for superconducting cables connected to the power grid system, provides a reference for superconducting cable application site selection and scheme comparison, and has a positive effect on promoting the practical application of superconducting cables .

In a specific embodiment, the present invention provides a method for evaluating a high-temperature superconducting cable access system, including:

(1) Calculate the technical evaluation index of superconducting cable access system

The advantages of high temperature superconducting cables, such as large capacity, small area, low loss, and environmental friendliness, are of great significance for solving high-density power transmission. The short-circuit current will also be different from that of ordinary cables, and the loss of superconducting cables is smaller than that of traditional cables. Based on this, four indicators of load balance, reliability, short-circuit current and line loss rate are proposed to evaluate the technology of superconducting cable access systems. characteristic.

(1) Reliability

Power supply reliability refers to the power supply point in the system containing superconducting cables to the users, including the substation, high and low voltage lines and household lines, and the entire power distribution system and equipment according to acceptable standards and its ability to meet the power demand of users . The power supply reliability index on the system side reflects the overall power supply reliability level of the system including superconducting cables, and the power supply reliability index on the user side reflects the ability of the distribution network to provide customized power services to users.

1) System Average Interruption Frequency (System Average Interruption Frequency) I _SAIF

Average number of continuous outages experienced by each user in a system containing superconducting cables within a specified time period:

为节点g的用户数；λ_g为负荷点g的年故障停运频率(次/年)。where g is the load node; Ω _F is the location set of all types of load nodes in the system;

is the number of users of node g; λ _g is the annual failure and outage frequency of load point g (times/year).

2) System Average Interruption Duration (System Average Interruption Duration) I _SAID

Average total outage time experienced by each user in a system containing superconducting cables within a specified time period:

In the formula: _ug is the average power outage duration (h/year) of the load point g.

3) System power supply reliability (Average Service Availability) I _ASA

The ratio of the total number of uninterrupted power hours experienced by the user to the total number of hours of power supply required by the user within the specified time:

(2) Transfer electricity:

After the superconducting cable is connected to the system, it is assumed that the maintenance state lasts for 48 hours and the load characteristics are not considered. The transmission power of the superconducting cable within 48 hours. The transferred power reflects the power transmission capacity of the superconducting cable access system, which needs to be calculated through the power flow.

(3) Short circuit current:

Short-circuit current calculation is one of the basic calculation methods of the power grid. Short-circuit current calculation is required in the selection of electrical equipment, performance verification or positive definiteness of protection devices. After the superconducting cable is connected to the system, the short-circuit current will change accordingly when the system fails.

The calculation methods of different short-circuit currents are as follows:

1) Three-phase short circuit

The three-phase short-circuit current calculation formula is as follows:

The named value is

是短路点的三相电流标幺值，

是短路点的三相短路电流有名值，

是归算后的总正序等值电抗。in,

is the per-unit value of the three-phase current at the short-circuit point,

is the named value of the three-phase short-circuit current at the short-circuit point,

is the reduced total positive sequence equivalent reactance.

2) Two-phase short circuit

The two-phase short-circuit current calculation formula is as follows:

是两相短路全电流，X_2∑是归算后的总负序等值电抗。in,

is the two-phase short-circuit full current, and X _2∑ is the total negative-sequence equivalent reactance after reduction.

Calculate the order components:

表示短路电流正序和负序分量，两相接地短路电流可表示为：

Represents the positive sequence and negative sequence components of the short-circuit current, and the two-phase-to-ground short-circuit current can be expressed as:

表示故障全电流，

表示正序故障电流分量。计算负序

和零序

分量公式如下：in,

represents the full fault current,

Indicates the positive sequence fault current component. Calculate Negative Order

and zero sequence

The formula for the components is as follows:

3) Calculation of single-phase short-circuit current

The formula for calculating the short-circuit current component at the single-phase ground fault point is:

Then the full current is:

(4) Line loss rate:

Electric energy is generated by the generator through primary energy conversion, and then passes through power transmission equipment, substation equipment, and power distribution equipment in turn, and finally is used by customers. The loss of energy, that is, the line loss.

The specific calculation formula of the line loss rate is as follows:

Line loss rate = (power supply - sales) ÷ power supply × 100%

As a comprehensive management indicator of power grid enterprises, line loss rate is related to marketing, production, power grid structure, operation mode, frequency regulation, measurement error, etc. The influencing factors can be roughly divided into power grid structure construction, power grid production technology, power grid operation and maintenance management aspects and external factors.

The theoretical line loss calculation of a system containing superconducting cables depends on the parameters of the distribution network, the collected electrical energy information, the operating data information, and the method used to calculate the line loss. Among them, the calculation method of the root mean square current method is as follows.

Assuming that the resistance is R and the current is i, then the active power loss of the corresponding electrical components will be:

Δp=3i ² R (12)

The power loss produced by this element in one day is:

Divide i according to the time series. When t is short enough, the power consumption corresponding to one day can be equivalent to:

or

In the formula, ΔA is the power consumption of the day, in kilowatt-hours; I _jf is the rms current of the day, in amperes; R is the resistance of the element, in ohms; t is the market in which the element operates, in hours.

(2) Calculate the economic evaluation index of superconducting cable access system

Economic evaluation of superconducting cables should take into account the cost of superconducting cables in the whole process from construction to use, that is, the full life cycle cost of superconducting cables. The whole life cycle cost is the sum of the costs incurred in the whole project cycle, which requires decision makers to consider the cost of the planning scheme from the perspective of macroscopic and long-term interests, so as to avoid the waste of resources in power grid planning.

Applying the concept of life cycle to power grid planning projects with superconducting cables is to maximize the overall benefits of the entire life cycle of enterprise assets with the goal of minimizing the total cost of the life cycle of the planning project under the premise of ensuring safe and undetermined power supply. change. The core content of the life cycle management of power grid construction projects is the analysis and calculation of the life cycle cost of the power grid planning scheme, and the quantitative value is used as the basis for decision-making. During the life cycle of power grid planning, construction and operation, the annual operation and maintenance cost often exceeds the initial investment cost of the power grid. The scheme with lower initial investment cost is not necessarily the optimal life cycle cost, and the scheme with higher initial investment cost The planning scheme may have lower operating costs in the later stage, so that the total cost of the planning scheme in the entire life cycle is lower; however, excessive construction costs may result in waste of resources and low asset utilization, which will eventually lead to the complete loss of the planning scheme. The increase in life cycle costs is not conducive to the development of enterprises.

(3) Comprehensive evaluation method of superconducting cable grid application feasibility

This chapter analyzes the common evaluation methods including the rank sum ratio method, the fuzzy comprehensive evaluation method and the TOPSIS method, and proposes a comprehensive evaluation combining the fuzzy membership function and the rank sum ratio method in combination with the characteristics of the feasibility evaluation problem of the superconducting cable power grid application. method.

(1) Rank sum ratio method

Rank-Sum Ratio (RSR) is a statistical analysis method proposed by Chinese scholar Tian Fengtiao in 1988, which combines the advantages of classical parameter estimation and modern nonparametric statistics. Among them, the rank sum ratio refers to the average of the row (or column) ranks in the table, which is a non-parametric measurement and has the characteristics of a continuous variable in the 0-1 interval. The basic idea is to obtain a dimensionless statistic RSR in a matrix of n rows (n evaluation objects) and m columns (m evaluation indicators) through rank transformation, and sort or classify the evaluation objects according to the RSR value. file sorting.

The rank sum ratio (RSR) is a carrier of composite information, and is essentially a general comprehensive index, that is, one index can be used to summarize the comprehensive level of multiple indicators, and it can reflect various aspects (different units of measurement, different categories and functions). ) combined effect.

The rank sum ratio method has the following advantages:

①The rank sum ratio is a new statistic, which is the carrier of composite information, with large capacity and strong plasticity;

②The rank sum ratio method is a new and extensive practical quantitative method, which integrates parametric statistics and non-parametric statistics, and can improve the level of statistical analysis and reanalysis;

③The rank sum ratio method has powerful statistical information function, strong pertinence, great flexibility, easy operation and high application value;

④By transplanting and grafting, using the obtained rank and ratio, it has a wide range of applications.

The basic process of applying the rank sum ratio method to divide the index interval is shown in Figure 3:

According to the mathematical expression of the rank sum ratio method, combined with the characteristics of the comprehensive evaluation of the active distribution network planning scheme, the RSR (rank sum ratio) calculation expression of the rank sum ratio method is:

In the formula, n is the number of objects to be evaluated, in this report the number of active distribution network planning schemes to be evaluated, m is the number of evaluation indicators, and R is the rank of each group of indicators obtained by sorting the evaluation objects.

The calculation expression of the RSR of the single-index rank sum ratio method for multiple evaluation objects is:

In the formula, n is the number of objects to be evaluated, and R is the rank of each group of indicators obtained by sorting the evaluation objects.

The number n of the objects to be evaluated is different, and the RSR value is also different. Generally, the larger the RSR value is, the better, that is, the RSR value is a benefit-type index. Therefore, the problem of ranking must be properly solved.

(2) Fuzzy comprehensive evaluation method

另类是U×V上的模糊关系，表现为m×n模糊矩阵R，这两类模糊集都是人们价值观念或偏好结构的反映。再对这两类集施加某种模糊运算，便得到V上的一个模糊子集

因此，模糊综合评价是指寻找模糊权重向量

以及一个从U到V的模糊变换

即对每一因素u_i单独做出一个判断

据此构造模糊矩阵R＝[r_ij]_m×n∈F(U×V)，其中r_ij表示因素u_i具有评语v_j的程度。进而求出模糊综合评价

其中b_j表示被评价对象具有评语v_j的程度，即v_j对模糊集

的隶属度。Fuzzy comprehensive evaluation is to use fuzzy mathematical tools to make a comprehensive evaluation of something under the influence of various factors. Let U = {u ₁ , u ₂ ,..., _um } be the m factors that characterize the object to be evaluated, and V = {v ₁ , v ₂ ,..., v _n } be the factor that characterizes the state of each factor n decisions. There are two types of fuzzy sets, taking subjective weighting as an example, one is the quantity that marks the importance of the elements in the factor set U in people's minds, which is expressed as the fuzzy weight vector on the factor set U

The other is the fuzzy relationship on U×V, which is represented by m×n fuzzy matrix R. These two types of fuzzy sets are the reflection of people’s values or preference structure. Then apply some kind of fuzzy operation to the two sets to get a fuzzy subset on V

Therefore, fuzzy comprehensive evaluation refers to finding the fuzzy weight vector

and a blur transform from U to V

That is to make a separate judgment for each factor u _i

Accordingly, a fuzzy matrix R=[r _ij ] _m×n ∈ F(U×V) is constructed, where r _ij represents the degree to which the factor _ui has the comment v _j . Then get the fuzzy comprehensive evaluation

where b _j represents the degree to which the object being evaluated has a comment v _j , that is, v _j is a pair of fuzzy sets

affiliation.

可诱导模糊关系R_f∈F(U×V)，其中

而由R_f可构成模糊矩阵：Depend on

Inducible fuzzy relation R _f ∈ F(U×V), where

And the fuzzy matrix can be formed by R _f :

通过

变换为决断集V上的模糊集

于是

构成一个综合评价模型，它像一个所示的转换器。若输入一个权重分配

则输出一个综合评价

如图5所示。For the weighted fuzzy vector on the factor set U

pass

Transform into a fuzzy set on the decision set V

then

Constitutes a comprehensive evaluation model that resembles a converter as shown. If you enter a weight assignment

Then output a comprehensive evaluation

As shown in Figure 5.

The basic steps of the fuzzy comprehensive evaluation method are as follows:

① Determine the evaluation object set, factor set and comment set;

Object set: O={o ₁ ,o ₂ ,...,o _l }, factor set: U={u ₁ ,u ₂ ,..., _um }, decision set: V={v ₁ ,v ₂ ,..., v _n }.

②Establish the weight distribution vector of m evaluation factors

Each factor in the evaluation factor set has a different status and role in the "evaluation target", that is, each evaluation factor occupies a different proportion, that is, the weight value.

③ Obtain fuzzy comprehensive evaluation matrix through fuzzy evaluation of each single factor;

其中R_i＝(r_i1,r_i2,…,r_in)为第i个因素u_i的单因素评价，所以r_ij表示第i(1≤i≤m)个因素u_i在第j(1≤j≤n)个评语v_j上的频率分布，一般将其归一化使之满足

Each evaluation object should establish a comprehensive evaluation matrix

where R _i =(r _i1 ,r _i2 ,...,r _in ) is the single-factor evaluation of the _i -th factor ui, so r _ij represents the i-th (1≤i≤m) factor u _i in the j(1 ≤j≤n) the frequency distribution on the comments v _j , which is generally normalized to satisfy

④Comprehensive evaluation results can be obtained by performing compound operations:

⑤ Calculate the comprehensive score of each evaluation object

转换为综合分值M，于是可依M值大小进行排序，从而可以挑选出最优者。The purpose of the comprehensive evaluation is to select the winning object from the object set, so it is also necessary to sort the comprehensive evaluation results of all objects, and combine the comprehensive evaluation results.

It is converted into a comprehensive score M, so it can be sorted according to the size of the M value, so that the best one can be selected.

The flowchart of fuzzy comprehensive evaluation processing is shown in Figure 5.

Fuzzy comprehensive evaluation method can transform incomplete information and uncertain information into fuzzy concepts, quantify qualitative problems, and improve the accuracy and credibility of evaluation. But it also has the following shortcomings:

①Only consider the role of the main factors, ignoring the secondary factors, so that the evaluation results are not comprehensive enough;

② When the number of indicators is large, the weight vector does not match the fuzzy matrix, which is easy to cause the evaluation to fail;

③The subjectivity of evaluation is obvious.

(3) TOPSIS method

The full name of TOPSIS is Technology for Order Preference by Similarity to Ideal Solution (Technique for Order Preference by Similarity to Ideal Solution). This evaluation method has no special requirements for data, is flexible and easy to use, and has a wide range of applications.

The "positive ideal solution" and "negative ideal solution" in the TOPSIS method are the two basic concepts of the TOPSIS method. The so-called positive ideal solution is an assumed optimal solution, and each of its attribute values reaches the best value among the alternatives; while the negative ideal solution is an assumed worst scheme, and its various attribute values reach the best value among the alternatives. The worst value among the alternatives. The rule for sorting the solutions is to compare the alternatives with the positive ideal solution and the negative ideal solution. If one of the alternatives is the closest to the ideal solution but far from the negative ideal solution, then the alternative is the best one. Program.

The basic idea of the TOPSIS method is: based on the normalized original data matrix, by calculating the weighted Euclidean distance between a certain scheme and the "positive ideal solution" and "negative ideal solution", the scheme and the positive ideal solution are obtained. The degree of closeness is used as the basis for evaluating the pros and cons of each scheme. The value of closeness is between 0 and 1. The closer the value is to 1, the closer the corresponding evaluation target is to the optimal level; otherwise, the closer the evaluation target is to the worst level.

Using TOPSIS for evaluation, the main steps are as follows:

① Form a decision matrix

Assume that the scheme set of the multi-index decision-making problem involved in the evaluation is M=(M ₁ , M ₂ ,...,M _m ), and the index set is D=(D ₁ , D ₂ ,..., D _n ), and the scheme Mi has an effect on the index Dj The value of is recorded as xij (i=1,2,...,m; j=1,2,...,n), then the decision matrix X formed is

②Dimensionless decision matrix

In order to eliminate the influence of different dimensions of each index on the decision-making of the scheme, it is necessary to perform dimensionless processing on the decision matrix, so as to construct a standardized matrix V=(v _ij ) _m×n .

③Construct a weighted decision matrix

Multiply each index weight W by the dimensionless matrix V. The weighted decision matrix R=(r _ij ) _{m×n is} obtained:

r _ij = w _j ·v _ij (i=1,2,...,m; j=1,2,...,n) (23)

In the formula, wj——the weight value of each indicator.

④ Calculate the positive ideal solution and the negative ideal solution

⑤ Calculate the distance between each scheme and the positive ideal solution and the negative ideal solution

When calculating, the Euclidean distance is used

The relative closeness η _i of each scheme to the positive ideal solution is expressed as:

The larger η _i is, the closer the decision scheme Mi is to a positive ideal solution, and the better the scheme is.

The TOPSIS method has no special requirements for sample data, and can sort the pros and cons of each evaluation object. And the method makes full use of the information of the original data, which is more in line with the actual situation. But there are also some shortcomings:

① When the index values of the two evaluation objects are symmetrical about the connection between the optimal solution and the worst solution, accurate results cannot be obtained;

② Only the pros and cons of each evaluation object can be sorted, and cannot be managed by grades, and the sensitivity is not high.

(4) Combination of fuzzy membership function and rank sum ratio method

In the evaluation of the distribution network planning scheme with superconducting cables, according to the calculated value of each index, the scheme ranking of the index can be known, that is, the corresponding rank of the index can be obtained, and the rank can be calculated by the calculated value of each index. The RSR of the sum-ratio method and the corresponding cumulative frequency f:

Among them, j represents the scheme to be evaluated whose rank is j, n is the total number of schemes, and the cumulative frequency of schemes with rank n is estimated. Convert the calculated cumulative frequency into a percentage value, and refer to the "Percentage and Probability Unit Comparison Table" in statistics to obtain the corresponding probability unit.

According to the rank sum ratio method, the quantitative indicators in the evaluation index system mentioned above are divided into bins. After obtaining the bin position, the interval value of the index bin is used as the parameter of the fuzzy membership function of the three types of indicators, and then each index is scored. To ensure a reasonable degree of discrimination of the evaluation results. Since there are only two types of evaluation indicators in this paper, the benefit type and the cost type, only the fuzzy membership function definitions of these two types of indicators are listed:

①Membership function of cost index

Where x is the index value, a and b are the undetermined parameters, and the function graph is shown in Figure 5:

②The membership function of the benefit index

Where x is the index value, c and d are the undetermined parameters, and the function graph is shown in Figure 7:

(4) Comprehensive evaluation of technology and economy of superconducting cable access system

(1) Comprehensive evaluation index system

Based on the above analysis, the technical indicators of the superconducting cable access system include load balance, reliability, short-circuit current and line loss rate; the economic indicator is the full life cycle cost, as shown in Figure 8.

(2) Comprehensive evaluation method

From the analysis in the previous chapter, it can be seen that both the fuzzy comprehensive evaluation method and the TOPSIS method have certain defects. Therefore, when there are few schemes, if the indicators of each scheme are not significantly different, the rank sum ratio method can be used for comprehensive evaluation; for the comparison schemes In many cases, the rank sum ratio method has the problem that it is difficult to classify the indexes when arranging ranks. Therefore, a fuzzy membership function is introduced, and the two are combined to quantify the evaluation indexes.

First, classify the evaluation indicators, determine the fuzzy membership function of the evaluation indicators, and then obtain the number of parameters. According to the calculated values of the evaluation indicators, use the rank sum ratio method to divide the grades. The number of grades depends on the number of parameters in the membership function. , the boundary value of different grades of the index can be obtained by the rank sum ratio method, which can be used as the parameter of the fuzzy membership function, and then the index evaluation result can be obtained.

(3) Comprehensive evaluation process

As shown in Figure 9, the comprehensive evaluation process is as follows:

1) Calculate technical and economic indicators

Calculate the transfer power of the superconducting cable access system based on the power flow results;

Based on the failure rate and average repair time of the superconducting cable, the reliability indicators such as the system average power outage frequency, the system average power outage duration and the system power supply reliability rate after the superconducting cable is connected to the system are calculated;

Calculate the short-circuit current after the superconducting cable is connected to the system based on the impedance value of the superconducting cable and the electrical simulation model;

Calculate the line loss rate of the superconducting cable added to the system based on the power supply and sales.

Based on the cost of superconducting cable, the cost of refrigerator, electricity price, transmission capacity and other parameters, the life cycle cost of superconducting cable is calculated.

2) Select feasible application scenarios based on reliability boundary conditions and full life cycle cost.

3) Use the rank sum ratio method to classify the technical and economic indicators of different schemes.

4) Take the interval value of the index bins as the parameter of the fuzzy membership function, and score each index.

Table 1 Attributes of various technical and economic indicators

5) Select the optimal plan or determine the feasibility of the plan according to the score. The higher the score, the better the plan.

For the case where there is only one solution to be evaluated, the score of the wiring solution is calculated according to the above process, and an appropriate threshold is given in combination with the actual situation, and the feasibility of the wiring solution is determined by judging whether the score of the solution reaches the threshold.

The present invention proposes four technical evaluation indexes, such as transfer power, reliability, short-circuit current and line loss rate, as well as economic evaluation indexes and whole life cycle cost; Based on the method, a comprehensive evaluation method combining fuzzy membership function and rank sum ratio method is proposed.

The comprehensive evaluation method of the high-temperature superconducting cable access system proposed by the present invention combines the classical evaluation method of power grid planning and the characteristics of the superconducting power transmission system. No matter when there is little difference in the comparison indicators or there are many options to be selected, the indicators can be graded Divide and evaluate the options to be selected quantitatively. The invention provides a comprehensive evaluation method for the superconducting cable connected to the power grid system, and provides a reference for the application site selection and scheme comparison of the superconducting cable. It has a positive effect on promoting the practical application of superconducting cables.

The second aspect.

10-11, an embodiment of the present invention provides an evaluation device for a high-temperature superconducting cable access system, including:

The technical and economic index calculation module 10 is used to obtain the relevant parameters of the superconducting cable, and calculate the technical and economic indicators according to the relevant parameters of the superconducting cable; wherein, the technical and economic indicators include: power supply reliability index, transfer power, short-circuit current , line loss rate and life cycle cost.

In a specific embodiment, the technical and economic index calculation module 10 is further used for:

The power supply reliability index is calculated based on the relevant parameters of the failure rate of the superconducting cable; wherein, the power supply reliability index includes: the system average power failure frequency, the system average power failure duration and the system power supply reliability rate.

Specifically, the average power outage frequency of the system is calculated by the following formula:

为负荷节点g的用户数，λ_g为负荷节点g的年故障停运频率。Among them, I _SAIF is the average power failure frequency of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node g, and λ _g is the annual fault outage frequency of load node g.

The average power outage duration of the system is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _SAID is the average power outage duration of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

The system power supply reliability rate is calculated by the following formula:

为负荷节点g的用户数，u_g为负荷节点g的平均停电持续时间。Among them, I _ASA is the reliability rate of power supply of the system, g is the load node, Ω _F is the location set of the load node,

is the number of users of load node _g , and ug is the average power outage duration of load node g.

Calculate the transfer power of the superconducting cable access system based on the power flow results.

Based on the impedance value of the superconducting cable and the electrical simulation model, the short-circuit current after the superconducting cable is connected to the system is calculated.

Calculate the line loss rate of the superconducting cable added to the system based on the power supply and sales.

Based on the cost of the superconducting cable, the cost of the refrigerator, the electricity price, and the transmission capacity, the life cycle cost of the superconducting cable is calculated.

The binning module 20 is used for binning the technical and economic indicators through the rank sum ratio method to obtain the interval value of the binning of the indicators.

The scoring module 30 is configured to use the interval value of the index classification as a parameter of the membership function, to score the technical and economic indicators, and obtain the score value of the technical and economic indicators.

In a specific embodiment, it also includes:

The application scenario selection module 40 is used to select several feasible application scenarios based on the reliability boundary conditions and the whole life cycle cost; according to the score value of the technical and economic indicators, select the feasible application scenarios from the several feasible application scenarios with higher feasibility The application scenario; wherein, the higher the score value of the technical and economic indicators, the higher the feasibility of the application scenario.

The invention combines the classical evaluation method of power grid planning and the characteristics of the superconducting power transmission system. No matter when the comparison index is not very different or there are many options to be selected, the index can be classified into grades, and the options to be selected can be quantitatively evaluated to connect the superconducting cables. The power grid system provides a comprehensive evaluation method, which provides a reference for the application site selection and scheme comparison of superconducting cables, and has a positive effect on promoting the practical application of superconducting cables.

The third aspect.

The present invention provides an electronic device comprising:

processors, memories and buses;

the bus for connecting the processor and the memory;

the memory for storing operation instructions;

The processor is used for invoking the operation instruction, and the executable instruction causes the processor to perform an operation corresponding to the evaluation method for a high-temperature superconducting cable access system as shown in the first aspect of the present application.

In an optional embodiment, an electronic device is provided. As shown in FIG. 12 , the electronic device 5000 shown in FIG. 12 includes: a processor 5001 and a memory 5003 . The processor 5001 is connected to the memory 5003, for example, through a bus 5002. Optionally, the electronic device 5000 may also include a transceiver 5004 . It should be noted that, in practical applications, the transceiver 5004 is not limited to one, and the structure of the electronic device 5000 does not constitute a limitation to the embodiments of the present application.

The processor 5001 may be a CPU, a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It may implement or execute the various exemplary logical blocks, modules and circuits described in connection with this disclosure. The processor 5001 may also be a combination that realizes computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and the like.

The bus 5002 may include a path to transfer information between the components described above. The bus 5002 may be a PCI bus, an EISA bus, or the like. The bus 5002 can be divided into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is shown in FIG. 12, but it does not mean that there is only one bus or one type of bus.

The memory 5003 can be ROM or other types of static storage devices that can store static information and instructions, RAM or other types of dynamic storage devices that can store information and instructions, or EEPROM, CD-ROM or other optical disk storage, optical disk storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or capable of carrying or storing desired program code in the form of instructions or data structures and capable of being executed by a computer Access any other medium without limitation.

The memory 5003 is used to store the application code for executing the solution of the present application, and the execution is controlled by the processor 5001 . The processor 5001 is configured to execute the application program code stored in the memory 5003, so as to implement the content shown in any of the foregoing method embodiments.

Among them, electronic devices include but are not limited to: mobile phones, notebook computers, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), in-vehicle terminals (such as in-vehicle navigation terminals), etc. Mobile terminals such as digital TVs, desktop computers, etc., as well as stationary terminals.

Fourth aspect.

The present invention provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, realizes the evaluation of the high-temperature superconducting cable access system shown in the first aspect of the present application method.

Yet another embodiment of the present application provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when it runs on a computer, the computer can execute the corresponding content in the foregoing method embodiments.

Claims (12)

1. An evaluation method of a high-temperature superconducting cable access system is characterized by comprising the following steps:

acquiring relevant parameters of the superconducting cable, and calculating technical and economic indexes according to the relevant parameters of the superconducting cable; wherein the technical and economic indicators include: power supply reliability index, transferred power quantity, short-circuit current, line loss rate and life cycle cost;

grading the technical and economic indexes through a rank and ratio method to obtain an index grading interval value;

and taking the interval value of the index grading as a parameter of the membership function, and grading the technical and economic index to obtain a grading value of the technical and economic index.

2. The method as claimed in claim 1, wherein after obtaining the value of the fraction of the technical-economic indicator, the method further comprises:

selecting a number of feasible application scenarios based on reliability boundary conditions and the full life cycle cost;

selecting an application scene with high feasibility from the feasible application scenes according to the score value of the technical and economic index; wherein, the higher the score value of the technical economic indicator, the higher the feasibility of the application scene.

3. The method for evaluating the hts cable access system according to claim 2, wherein the calculating the technical-economic indicator according to the relevant parameters of the superconducting cable comprises:

calculating a power supply reliability index based on the fault rate related parameters of the superconducting cable; wherein the power supply reliability index comprises: the average power failure frequency of the system, the average power failure duration time of the system and the power supply reliability of the system;

calculating the transfer electric quantity of the superconducting cable access system based on the load flow result;

calculating the short-circuit current of the superconducting cable after the superconducting cable is connected into the system based on the impedance value of the superconducting cable and the electrical simulation model;

calculating the line loss rate of the adding system of the superconducting cable based on the power supply quantity and the electricity selling quantity;

the total life cycle cost of the superconducting cable is calculated based on the manufacturing cost of the superconducting cable, the manufacturing cost of the refrigerating machine, the electricity price and the conveying capacity.

4. The method for evaluating a HTC access system as claimed in claim 3,

the average power failure frequency of the system is calculated by the following formula:

wherein, I_SAIFAveraging the frequency of power outages for the systemG is the load node, Ω_FIs a set of locations for the load node,

is the number of users, lambda, of the load node g_gThe annual outage frequency of the load node g.

5. The method for evaluating a HTC access system as claimed in claim 3,

the average power failure duration of the system is calculated by the following formula:

wherein, I_SAIDMean time duration of system outage, g load node, Ω_FIs a set of locations for the load node,

as a load node_gNumber of users u_gThe average outage duration of the load node g.

6. The method for evaluating a HTC access system as claimed in claim 3,

the system power supply reliability is calculated by the following formula:

wherein, I_ASAReliability of power supply for the system, g is load node, omega_FIs a set of locations for the load node,

is the number u of users of the load node g_gAverage power failure for load node gThe duration of time.

7. An evaluation device for a high-temperature superconducting cable connection system, comprising:

the technical and economic index calculation module is used for acquiring relevant parameters of the superconducting cable and calculating the technical and economic indexes according to the relevant parameters of the superconducting cable; wherein the technical and economic indicators include: power supply reliability index, transferred power quantity, short-circuit current, line loss rate and life cycle cost;

the grading module is used for grading the technical and economic indexes through a rank and ratio method to obtain an index grading interval value;

and the scoring module is used for scoring the technical and economic indexes by taking the interval values of the index grades as parameters of the membership function to obtain the score values of the technical and economic indexes.

8. The apparatus for evaluating a hts cable access system of claim 7, further comprising:

an application scenario selection module for selecting a plurality of feasible application scenarios based on reliability boundary conditions and the life cycle cost; selecting an application scene with high feasibility from the feasible application scenes according to the score value of the technical and economic index; wherein, the higher the score value of the technical economic indicator, the higher the feasibility of the application scene.

9. The apparatus for evaluating an hts cable access system of claim 8, wherein the technical-economic indicator calculating module is further configured to:

calculating a power supply reliability index based on the fault rate related parameters of the superconducting cable; wherein the power supply reliability index comprises: the average power failure frequency of the system, the average power failure duration time of the system and the power supply reliability of the system;

calculating the transfer electric quantity of the superconducting cable access system based on the load flow result;

calculating the short-circuit current of the superconducting cable after the superconducting cable is connected into the system based on the impedance value of the superconducting cable and the electrical simulation model:

calculating the line loss rate of the adding system of the superconducting cable based on the power supply quantity and the electricity selling quantity;

the total life cycle cost of the superconducting cable is calculated based on the manufacturing cost of the superconducting cable, the manufacturing cost of the refrigerating machine, the electricity price and the conveying capacity.

10. The apparatus for evaluating a hts cable access system of claim 9,

the average power failure frequency of the system is calculated by the following formula:

wherein, I_SAIFFor the average system outage frequency, g is the load node, Ω_FIs a set of locations for the load node,

is the number of users, lambda, of the load node g_gThe annual outage frequency of the load node g.

11. The apparatus for evaluating a hts cable access system of claim 9,

the average power failure duration of the system is calculated by the following formula:

wherein, I_SAIDMean time duration of system outage, g load node, Ω_FIs a set of locations for the load node,

is the number u of users of the load node g_gBeing a load node gAverage outage duration.

12. The apparatus for evaluating a hts cable access system of claim 9,

the system power supply reliability is calculated by the following formula:

wherein, I_ASAReliability of power supply for the system, g is load node, omega_FIs a set of locations for the load node,

is the number u of users of the load node g_gThe average outage duration of the load node g.

Images